explanation      blue bibcodes open ADS page with paths to full text
Author name code: fletcher
ADS astronomy entries on 2022-09-14
author:"Fletcher, Lyndsay" 

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Title: Flare Kernels May be Smaller than You Think: Modelling the
    Radiative Response of Chromospheric Plasma Adjacent to a Solar Flare
Authors: Osborne, Christopher M. J.; Fletcher, Lyndsay
2022arXiv220903238O    Altcode:
  Numerical models of solar flares typically focus on the behaviour
  of directly-heated flare models, adopting magnetic field- aligned,
  plane-parallel methodologies. With high spatial- and spectral-resolution
  ground-based optical observations of flares, it is essential also
  to understand the response of the plasma surrounding these strongly
  heated volumes. We investigate the effects of the extreme radiation
  field produced by a heated column of flare plasma on an adjacent slab
  of chromospheric plasma, using a two-dimensional radiative transfer
  model and considering the time-dependent solution to the atomic level
  populations and electron density throughout this model. The outgoing
  spectra of H$\alpha$ and Ca II 854.2 nm synthesised from our slab show
  significant spatial-, time-, and wavelength-dependent variations (both
  enhancements and reductions) in the line cores, extending on order 1 Mm
  into the non-flaring slab due to the incident transverse radiation field
  from the flaring boundary. This may lead to significant overestimates of
  the sizes of directly-heated flare kernels, if line-core observations
  are used. However, the radiation field alone is insufficient to drive
  any significant changes in continuum intensity, due to the typical
  photospheric depths at which they forms, so continuum sources will not
  have an apparent increase in size. We show that the line formation
  regions near the flaring boundary can be driven upwards in altitude
  by over 1 Mm despite the primary thermodynamic parameters (other than
  electron density) being held horizontally uniform. This work shows
  that in simple models these effects are significant and should be
  considered further in future flare modelling and interpretation.

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Title: Fast prograde coronal flows in solar active regions
Authors: Hudson, Hugh S.; Mulay, Sargam M.; Fletcher, Lyndsay;
   Docherty, Jennifer; Fitzpatrick, Jimmy; Pike, Eleanor; Strong, Morven;
   Chamberlin, Phillip C.; Woods, Thomas N.
2022MNRAS.515L..84H    Altcode: 2022MNRAS.tmpL..75H; 2022arXiv220713461H
  We report the discovery and characterization of high-speed (>100 km
  s<SUP>-1</SUP>) horizontal flows in solar active regions, making use
  of the Sun-as-a-star spectroscopy in the range 5-105 nm provided by
  the EVE (Extreme Ultraviolet Variability Experiment) spectrometers on
  the Solar Dynamics Observatory. These apparent flows are persistent on
  time-scales of days, and are well observed in lines of Mg X, Si XII,
  and Fe XVI for example. They are prograde, as evidenced directly
  by blueshifts/redshifts peaking at the east/west limb passages of
  isolated active regions. The high-speed flow behaviour does not depend
  upon active-region latitude or solar cycle, with similar behaviour in
  Cycles 24 and 25.

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Title: Development of Integral Field Spectrographs to Revolutionize
    Spectroscopic Observations of Solar Flares and other Energetic
    Solar Eruptions
Authors: Lin, Haosheng; Anan, Tetsu; Cauzzi, Gianna; Fletcher, Lyndsay;
   Huang, Pei; Kowalski, Adam; Kramar, Maxim; Qiu, Jiong; Samra, Jenna;
   Spittler, Constance; Sukegawa, Takashi; Wirth, Gregory
2022arXiv220900788L    Altcode:
  The Sun's proximity offers us a unique opportunity to study in detail
  the physical processes on a star's surface; however, the highly dynamic
  nature of the stellar surface -- in particular, energetic eruptions
  such as flares and coronal mass ejections -- presents tremendous
  observational challenges. Spectroscopy probes the physical state of
  the solar atmosphere, but conventional scanning spectrographs and
  spectrometers are unable to capture the full evolutionary history of
  these dynamic events with a sufficiently wide field of view and high
  spatial, spectral, and temporal resolution. Resolving the physics of the
  dynamic sun requires gathering simultaneous spectra across a contiguous
  area over the full duration of these events, a goal now tantalizingly
  close to achievable with continued investment in developing powerful
  new Integral Field Spectrographs to serve as the foundation of both
  future ground- and space-based missions. This technology promises to
  revolutionize our ability to study solar flares and CMEs, addressing
  NASA's strategic objective to "understand the Sun, solar system, and
  universe." Since such events generate electromagnetic radiation and
  high-energy particles that disrupt terrestrial electric infrastructure,
  this investment not only advances humanity's scientific endeavors
  but also enhances our space weather forecasting capability to protect
  against threats to our technology-reliant civilization.

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Title: Ice Giant Atmospheric Structures from Spitzer and How the
    James Webb Space Telescope will Advance Our Understanding
Authors: Rowe-Gurney, N.; Fletcher, L. N.; Orton, G. S.; Roman, M. T.;
   Sinclair, J. A.; Moses, J. I.; Irwin, P. G. J.; Milam, S. N.; Hammel,
   H. B.
2022LPICo2686.4045R    Altcode:
  NASA's IRS acquired mid-infrared disc-averaged spectra of Uranus &amp;
  Neptune 2004-2007. We analyze the differences in temperature &amp;
  composition between the separate hemispheres to shed light on the
  variability of stratospheres and upper tropospheres.

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Title: Hazy Blue Worlds: A Holistic Aerosol Model for Uranus and
    Neptune, Including Dark Spots
Authors: Irwin, P. G. J.; Teanby, N. A.; Fletcher, L. N.; Toledo,
   D.; Orton, G. S.; Wong, M. H.; Roman, M. T.; Pérez-Hoyos, S.; James,
   A.; Dobinson, J.
2022JGRE..12707189I    Altcode: 2022arXiv220104516I
  We present a reanalysis (using the Minnaert limb-darkening
  approximation) of visible/near-infrared (0.3-2.5 μm) observations of
  Uranus and Neptune made by several instruments. We find a common model
  of the vertical aerosol distribution i.e., consistent with the observed
  reflectivity spectra of both planets, consisting of: (a) a deep aerosol
  layer with a base pressure &gt;5-7 bar, assumed to be composed of a
  mixture of H<SUB>2</SUB>S ice and photochemical haze; (b) a layer of
  photochemical haze/ice, coincident with a layer of high static stability
  at the methane condensation level at 1-2 bar; and (c) an extended layer
  of photochemical haze, likely mostly of the same composition as the
  1-2-bar layer, extending from this level up through to the stratosphere,
  where the photochemical haze particles are thought to be produced. For
  Neptune, we find that we also need to add a thin layer of micron-sized
  methane ice particles at ∼0.2 bar to explain the enhanced reflection
  at longer methane-absorbing wavelengths. We suggest that methane
  condensing onto the haze particles at the base of the 1-2-bar aerosol
  layer forms ice/haze particles that grow very quickly to large size
  and immediately "snow out" (as predicted by Carlson et al. (1988), <A
  href="https://doi.org/10.1175/1520-0469(1988)045%3C2066:CMOTGP%3E2.0.CO2">https://doi.org/10.1175/1520-0469(1988)045&lt;2066:CMOTGP&gt;2.0.CO2</A>),
  re-evaporating at deeper levels to release their core haze particles
  to act as condensation nuclei for H<SUB>2</SUB>S ice formation. In
  addition, we find that the spectral characteristics of "dark spots",
  such as the Voyager-2/ISS Great Dark Spot and the HST/WFC3 NDS-2018,
  are well modelled by a darkening or possibly clearing of the deep
  aerosol layer only.

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Title: First high resolution interferometric observation of a solar
    prominence with ALMA
Authors: Labrosse, Nicolas; Rodger, Andrew S.; Radziszewski, Krzysztof;
   Rudawy, Paweł; Antolin, Patrick; Fletcher, Lyndsay; Levens, Peter J.;
   Peat, Aaron W.; Schmieder, Brigitte; Simões, Paulo J. A.
2022MNRAS.513L..30L    Altcode: 2022arXiv220212434L; 2022MNRAS.tmpL..22L
  We present the first observation of a solar prominence at 84 - 116 GHz
  using the high resolution interferometric imaging of ALMA. Simultaneous
  observations in Hα from Białkaw Observatory and with SDO/AIA reveal
  similar prominence morphology to the ALMA observation. The contribution
  functions of 3 mm and Hα emission are shown to have significant
  overlap across a range of gas pressures. We estimate the maximum
  millimetre-continuum optical thickness to be τ<SUB>3mm</SUB> ≍ 2,
  and the brightness temperature from the observed Hα intensity. The
  brightness temperature measured by ALMA is ~6000 - 7000 K in the
  prominence spine, which correlates well with the estimated brightness
  temperature for a kinetic temperature of 8000 K.

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Title: Compositional Mapping of Ganymede with VLT/SPHERE Using Markov
    Chain Monte Carlo Spectral Analysis
Authors: King, O. R. T.; Fletcher, L. N.
2022LPICo2678.1461K    Altcode:
  Infrared spectral observations of Ganymede from VLT/SPHERE have been
  analysed using a Monte Carlo model to calculate compositional abundances
  and uncertainties.

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Title: Probing the Physics of the Solar Atmosphere with the Multi-slit
    Solar Explorer (MUSE). II. Flares and Eruptions
Authors: Cheung, Mark C. M.; Martínez-Sykora, Juan; Testa, Paola;
   De Pontieu, Bart; Chintzoglou, Georgios; Rempel, Matthias; Polito,
   Vanessa; Kerr, Graham S.; Reeves, Katharine K.; Fletcher, Lyndsay; Jin,
   Meng; Nóbrega-Siverio, Daniel; Danilovic, Sanja; Antolin, Patrick;
   Allred, Joel; Hansteen, Viggo; Ugarte-Urra, Ignacio; DeLuca, Edward;
   Longcope, Dana; Takasao, Shinsuke; DeRosa, Marc L.; Boerner, Paul;
   Jaeggli, Sarah; Nitta, Nariaki V.; Daw, Adrian; Carlsson, Mats; Golub,
   Leon; The
2022ApJ...926...53C    Altcode: 2021arXiv210615591C
  Current state-of-the-art spectrographs cannot resolve the fundamental
  spatial (subarcseconds) and temporal (less than a few tens of
  seconds) scales of the coronal dynamics of solar flares and eruptive
  phenomena. The highest-resolution coronal data to date are based on
  imaging, which is blind to many of the processes that drive coronal
  energetics and dynamics. As shown by the Interface Region Imaging
  Spectrograph for the low solar atmosphere, we need high-resolution
  spectroscopic measurements with simultaneous imaging to understand the
  dominant processes. In this paper: (1) we introduce the Multi-slit Solar
  Explorer (MUSE), a spaceborne observatory to fill this observational
  gap by providing high-cadence (&lt;20 s), subarcsecond-resolution
  spectroscopic rasters over an active region size of the solar transition
  region and corona; (2) using advanced numerical models, we demonstrate
  the unique diagnostic capabilities of MUSE for exploring solar coronal
  dynamics and for constraining and discriminating models of solar flares
  and eruptions; (3) we discuss the key contributions MUSE would make
  in addressing the science objectives of the Next Generation Solar
  Physics Mission (NGSPM), and how MUSE, the high-throughput Extreme
  Ultraviolet Solar Telescope, and the Daniel K Inouye Solar Telescope
  (and other ground-based observatories) can operate as a distributed
  implementation of the NGSPM. This is a companion paper to De Pontieu
  et al., which focuses on investigating coronal heating with MUSE.

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Title: Probing the Physics of the Solar Atmosphere with the Multi-slit
Solar Explorer (MUSE): II. Flares and Eruptions
Authors: Cheung, Chun Ming Mark; Martinez-Sykora, Juan; Testa, Paola;
   De Pontieu, Bart; Chintzoglou, Georgios; Rempel, Matthias; Polito,
   Vanessa; Kerr, Graham; Reeves, Katharine; Fletcher, Lyndsay; Jin,
   Meng; Nobrega, Daniel; Danilovic, Sanja; Antolin, Patrick; Allred,
   Joel; Hansteen, Viggo; Ugarte-Urra, Ignacio; DeLuca, Edward; Longcope,
   Dana; Takasao, Shinsuke; DeRosa, Marc; Boerner, Paul; Jaeggli, Sarah;
   Nitta, Nariaki; Daw, Adrian; Carlsson, Mats; Golub, Leon
2021AGUFMSH51A..08C    Altcode:
  Current state-of-the-art spectrographs cannot resolve the fundamental
  spatial (sub-arcseconds) and temporal scales (less than a few tens
  of seconds) of the coronal dynamics of solar flares and eruptive
  phenomena. The highest resolution coronal data to date are based on
  imaging, which is blind to many of the processes that drive coronal
  energetics and dynamics. As shown by IRIS for the low solar atmosphere,
  we need high-resolution spectroscopic measurements with simultaneous
  imaging to understand the dominant processes. In this paper: (1)
  we introduce the Multi-slit Solar Explorer (MUSE), a spaceborne
  observatory to fill this observational gap by providing high-cadence
  (&lt;20 s), sub-arcsecond resolution spectroscopic rasters over an
  active region size of the solar transition region and corona; (2)
  using advanced numerical models, we demonstrate the unique diagnostic
  capabilities of MUSE for exploring solar coronal dynamics, and for
  constraining and discriminating models of solar flares and eruptions;
  (3) we discuss the key contributions MUSE would make in addressing the
  science objectives of the Next Generation Solar Physics Mission (NGSPM),
  and how MUSE, the high-throughput EUV Solar Telescope (EUVST) and the
  Daniel K Inouye Solar Telescope (and other ground-based observatories)
  can operate as a distributed implementation of the NGSPM. This is a
  companion paper to De Pontieu et al. (2021, also submitted to SH-17),
  which focuses on investigating coronal heating with MUSE.

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Title: Hot onsets of solar flares
Authors: Hudson, Hugh; Fletcher, Lyndsay; Hannah, Iain; Hayes, Laura;
   Simoes, Paulo
2021AGUFMSH22B..02H    Altcode:
  The GOES/XRS data show low-level soft X-ray emissions prior to
  a flare in a "hot onset" precursor of the main flare development
  (2021MNRAS.501.1273H). This phenomenon provides clear evidence for
  energy release not identifiable with the impulsive phase, and apparently
  not mediated by non-thermal particles. The hot onset phase may last for
  tens of seconds to minutes, characterized by gradual and roughly linear
  growth of emission measure at characteristic isothermal temperatures
  of 10-15 MK and no clear pattern of temperature increase in the sense
  of dT/dt &gt; 0. The figure shows an example of this behavior, from
  SOL2004-02-26 (X1.1). The newer GOES-R data also show this effect,
  providing higher time resolution (1 s) and better noise properties,
  although with higher background levels. Hot onsets occur in most if
  not all flares, but their properties do not appear to provide any
  guidance towards the magnitude of the flare that follows.

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Title: Microwave observations reveal the deep extent and structure
    of Jupiter’s atmospheric vortices
Authors: Bolton, S. J.; Levin, S. M.; Guillot, T.; Li, C.; Kaspi, Y.;
   Orton, G.; Wong, M. H.; Oyafuso, F.; Allison, M.; Arballo, J.; Atreya,
   S.; Becker, H. N.; Bloxham, J.; Brown, S. T.; Fletcher, L. N.; Galanti,
   E.; Gulkis, S.; Janssen, M.; Ingersoll, A.; Lunine, J. L.; Misra,
   S.; Steffes, P.; Stevenson, D.; Waite, J. H.; Yadav, R. K.; Zhang, Z.
2021Sci...374..968B    Altcode:
  Jupiter’s atmosphere has a system of zones and belts punctuated by
  small and large vortices, the largest being the Great Red Spot. How
  these features change with depth is unknown, with theories of their
  structure ranging from shallow meteorological features to surface
  expressions of deep-seated convection. We present observations
  of atmospheric vortices using the Juno spacecraft’s Microwave
  Radiometer. We found vortex roots that extend deeper than the altitude
  at which water is expected to condense, and we identified density
  inversion layers. Our results constrain the three-dimensional structure
  of Jupiter’s vortices and their extension below the clouds.

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Title: The high-energy Sun - probing the origins of particle
    acceleration on our nearest star
Authors: Matthews, S. A.; Reid, H. A. S.; Baker, D.; Bloomfield, D. S.;
   Browning, P. K.; Calcines, A.; Del Zanna, G.; Erdelyi, R.; Fletcher,
   L.; Hannah, I. G.; Jeffrey, N.; Klein, L.; Krucker, S.; Kontar, E.;
   Long, D. M.; MacKinnon, A.; Mann, G.; Mathioudakis, M.; Milligan,
   R.; Nakariakov, V. M.; Pesce-Rollins, M.; Shih, A. Y.; Smith, D.;
   Veronig, A.; Vilmer, N.
2021ExA...tmp..135M    Altcode:
  As a frequent and energetic particle accelerator, our Sun provides
  us with an excellent astrophysical laboratory for understanding
  the fundamental process of particle acceleration. The exploitation
  of radiative diagnostics from electrons has shown that acceleration
  operates on sub-second time scales in a complex magnetic environment,
  where direct electric fields, wave turbulence, and shock waves all
  must contribute, although precise details are severely lacking. Ions
  were assumed to be accelerated in a similar manner to electrons, but
  γ-ray imaging confirmed that emission sources are spatially separated
  from X-ray sources, suggesting distinctly different acceleration
  mechanisms. Current X-ray and γ-ray spectroscopy provides only a basic
  understanding of accelerated particle spectra and the total energy
  budgets are therefore poorly constrained. Additionally, the recent
  detection of relativistic ion signatures lasting many hours, without
  an electron counterpart, is an enigma. We propose a single platform
  to directly measure the physical conditions present in the energy
  release sites and the environment in which the particles propagate and
  deposit their energy. To address this fundamental issue, we set out
  a suite of dedicated instruments that will probe both electrons and
  ions simultaneously to observe; high (seconds) temporal resolution
  photon spectra (4 keV - 150 MeV) with simultaneous imaging (1 keV -
  30 MeV), polarization measurements (5-1000 keV) and high spatial and
  temporal resolution imaging spectroscopy in the UV/EUV/SXR (soft X-ray)
  regimes. These instruments will observe the broad range of radiative
  signatures produced in the solar atmosphere by accelerated particles.

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Title: On the importance of Ca II photoionization by the hydrogen
    lyman transitions in solar flare models
Authors: Osborne, C. M. J.; Heinzel, P.; Kašparová, J.; Fletcher, L.
2021MNRAS.507.1972O    Altcode: 2021MNRAS.tmp.1947O; 2021arXiv210711145O
  The forward fitting of solar flare observations with
  radiation-hydrodynamic simulations is a common technique for learning
  about energy deposition and atmospheric evolution during these explosive
  events. A frequent spectral line choice for this process is Ca II
  854.2 nm due to its formation in the chromosphere and substantial
  variability. It is important to ensure that this line is accurately
  modelled to obtain the correct interpretation of observations. Here,
  we investigate the importance of photoionization of Ca II to Ca III by
  the hydrogen Lyman transitions, whilst the Lyman continuum is typically
  considered in this context in simulations, the associated bound-bound
  transitions are not. This investigation uses two RADYN flare simulations
  and reprocesses the radiative transfer using the Lightweaver framework
  which accounts for the overlapping of all active transitions. The
  Ca II 854.2 nm line profiles are found to vary significantly due to
  photoionization by the Lyman lines, showing notably different shapes
  and even reversed asymmetries. Finally, we investigate to what extent
  these effects modify the energy balance of the simulation and the
  implications on future radiation-hydrodynamic simulations. There
  is found to be a 10-15 per cent change in detailed optically thick
  radiative losses from considering these photoionization effects on
  the calcium lines in the two simulations presented, demonstrating the
  importance of considering these effects in a self-consistent way.

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Title: Jupiter's Temperate Belt/Zone Contrasts Revealed at Depth by
    Juno Microwave Observations
Authors: Fletcher, L. N.; Oyafuso, F. A.; Allison, M.; Ingersoll, A.;
   Li, L.; Kaspi, Y.; Galanti, E.; Wong, M. H.; Orton, G. S.; Duer, K.;
   Zhang, Z.; Li, C.; Guillot, T.; Levin, S. M.; Bolton, S.
2021JGRE..12606858F    Altcode: 2021arXiv211014620F
  Juno microwave radiometer (MWR) observations of Jupiter's midlatitudes
  reveal a strong correlation between brightness temperature contrasts and
  zonal winds, confirming that the banded structure extends throughout the
  troposphere. However, the microwave brightness gradient is observed to
  change sign with depth: the belts are microwave-bright in the p&lt;5 bar
  range and microwave-dark in the p&gt;10 bar range. The transition level
  (which we call the "jovicline") is evident in the MWR 11.5 cm channel,
  which samples the 5-14 bar range when using the limb-darkening at
  all emission angles. The transition is located between 4 and 10 bars,
  and implies that belts change with depth from being NH3-depleted to
  NH3-enriched, or from physically warm to physically cool, or more
  likely a combination of both. The change in character occurs near
  the statically stable layer associated with water condensation. The
  implications of the transition are discussed in terms of ammonia
  redistribution via meridional circulation cells with opposing flows
  above and below the water condensation layer, and in terms of the
  "mushball" precipitation model, which predicts steeper vertical ammonia
  gradients in the belts versus the zones. We show via the moist thermal
  wind equation that both the temperature and ammonia interpretations can
  lead to vertical shear on the zonal winds, but the shear is ∼50×
  weaker if only NH3 gradients are considered. Conversely, if MWR
  observations are associated with kinetic temperature gradients then
  it would produce zonal winds that increase in strength down to the
  "jovicline", consistent with Galileo probe measurements; then decay
  slowly at higher pressures.

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Title: Demonstration of an x-ray Raman spectroscopy setup to study
    warm dense carbon at the high energy density instrument of European
    XFEL
Authors: Voigt, K.; Zhang, M.; Ramakrishna, K.; Amouretti, A.; Appel,
   K.; Brambrink, E.; Cerantola, V.; Chekrygina, D.; Döppner, T.;
   Falcone, R. W.; Falk, K.; Fletcher, L. B.; Gericke, D. O.; Göde,
   S.; Harmand, M.; Hartley, N. J.; Hau-Riege, S. P.; Huang, L. G.;
   Humphries, O. S.; Lokamani, M.; Makita, M.; Pelka, A.; Prescher, C.;
   Schuster, A. K.; Šmíd, M.; Toncian, T.; Vorberger, J.; Zastrau,
   U.; Preston, T. R.; Kraus, D.
2021PhPl...28h2701V    Altcode:
  We present a proof-of-principle study demonstrating x-ray Raman
  Spectroscopy (XRS) from carbon samples at ambient conditions in
  conjunction with other common diagnostics to study warm dense
  matter, performed at the high energy density scientific instrument
  of the European x-ray Free Electron Laser (European XFEL). We obtain
  sufficient spectral resolution to identify the local structure and
  chemical bonding of diamond and graphite samples, using highly annealed
  pyrolytic graphite spectrometers. Due to the high crystal reflectivity
  and XFEL brightness, we obtain signal strengths that will enable
  accurate XRS measurements in upcoming pump-probe experiments with a
  high repetition-rate, where the samples will be pumped with high-power
  lasers. Molecular dynamics simulations based on density functional
  theory together with XRS simulations demonstrate the potential of this
  technique and show predictions for high-energy-density conditions. Our
  setup allows simultaneous implementation of several different diagnostic
  methods to reduce ambiguities in the analysis of the experimental
  results, which, for warm dense matter, often relies on simplifying
  model assumptions. The promising capabilities demonstrated here provide
  unprecedented insights into chemical and structural dynamics in warm
  dense matter states of light elements, including conditions similar
  to the interiors of planets, low-mass stars, and other celestial bodies.

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Title: VizieR Online Data Catalog: TEXES spectra of Saturn from
    February 03 2013 (Blake+, 2021)
Authors: Blake, J. S. D.; Fletcher, L. N.; Greathouse, T. K.; Orton,
   G. S.; Melin, H.; Roman, M. T.; Antunano, A.; Donnelly, P. T.;
   Rowe-Gurney, N.; King, O.
2021yCat..36530066B    Altcode:
  We observed Saturn in the N-band 8.6 m region for one night in February
  2013, using the high spectral resolution of the TEXES instrument and
  the 3-meter diameter mirror of NASA's IRTF. <P />TEXES spectra of
  Saturn from February 03 2013. <P />(2 data files).

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Title: In Situ exploration of the giant planets
Authors: Mousis, O.; Atkinson, D. H.; Ambrosi, R.; Atreya, S.;
   Banfield, D.; Barabash, S.; Blanc, M.; Cavalié, T.; Coustenis,
   A.; Deleuil, M.; Durry, G.; Ferri, F.; Fletcher, L. N.; Fouchet, T.;
   Guillot, T.; Hartogh, P.; Hueso, R.; Hofstadter, M.; Lebreton, J. -P.;
   Mandt, K. E.; Rauer, H.; Rannou, P.; Renard, J. -B.; Sánchez-Lavega,
   A.; Sayanagi, K. M.; Simon, A. A.; Spilker, T.; Venkatapathy, E.;
   Waite, J. H.; Wurz, P.
2021ExA...tmp...96M    Altcode:
  Remote sensing observations suffer significant limitations when used
  to study the bulk atmospheric composition of the giant planets of our
  Solar System. This impacts our knowledge of the formation of these
  planets and the physics of their atmospheres. A remarkable example of
  the superiority of in situ probe measurements was illustrated by the
  exploration of Jupiter, where key measurements such as the determination
  of the noble gases' abundances and the precise measurement of the helium
  mixing ratio were only made available through in situ measurements
  by the Galileo probe. Here we describe the main scientific goals to
  be addressed by the future in situ exploration of Saturn, Uranus, and
  Neptune, placing the Galileo probe exploration of Jupiter in a broader
  context. An atmospheric entry probe targeting the 10-bar level would
  yield insight into two broad themes: i) the formation history of the
  giant planets and that of the Solar System, and ii) the processes at
  play in planetary atmospheres. The probe would descend under parachute
  to measure composition, structure, and dynamics, with data returned
  to Earth using a Carrier Relay Spacecraft as a relay station. An
  atmospheric probe could represent a significant ESA contribution to
  a future NASA New Frontiers or flagship mission to be launched toward
  Saturn, Uranus, and/or Neptune.

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Title: Characterizing a "Solar FRB"
Authors: Hudson, H.; Briggs, M.; Chitta, L.; Fletcher, L.; Gary, D.;
   Monstein, C.; Nimmo, K.; Saint-Hilaire, P.; White, S.
2021AAS...23812716H    Altcode:
  A remarkable solar microwave (1.4 GHz) burst,
  SOL2019-05-06T17:47:35.385, has been reported by the STARE2 fast cosmic
  transient survey (Bochenek et al., 2020). Its behavior resembles
  that of the Fast Radio Burst (FRB) extragalactic events in having a
  relatively broad spectral bandwidth and brief (19-msec) duration. It
  also had no measureable dispersion. The associated flare, GOES class
  C1, had a relatively hard X-ray spectrum as observed by Fermi/GBM,
  but no temporal association at the msec time scale suggested by the
  microwaves. Although msec variability in the microwave domain has
  been known to solar radio astronomy since the 1970s, the brightness
  and isolation of this event (both spatial and temporal) suggests
  novelty. Accordingly we survey the available correlative data from
  many sources and discuss possible interpretations in terms of type
  III-like behavior, electron cyclotron masering, and gyrosynchrotron
  emission. We note that the radio data (e-Callisto and EOVSA) revealed
  abundant type III activity in the vicinity, and the related flares
  as observed by GOES had exceptionally short time scales, suggesting
  burst origins in the lower solar atmosphere.

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Title: Evidence of chromospheric molecular hydrogen emission in a
    solar flare observed by the IRIS satellite
Authors: Mulay, Sargam M.; Fletcher, Lyndsay
2021MNRAS.504.2842M    Altcode: 2021arXiv210203329M; 2021MNRAS.tmp..434M
  We have carried out the first comprehensive investigation of enhanced
  line emission from molecular hydrogen, H<SUB>2</SUB> at 1333.79 Å,
  observed at flare ribbons in SOL2014-04-18T13:03. The cool H<SUB>2</SUB>
  emission is known to be fluorescently excited by Si IV 1402.77 Å
  UV radiation and provides a unique view of the temperature minimum
  region (TMR). Strong H<SUB>2</SUB> emission was observed when the Si
  IV 1402.77 Å emission was bright during the flare impulsive phase and
  gradual decay phase, but it dimmed during the GOES peak. H<SUB>2</SUB>
  line broadening showed non-thermal speeds in the range 7-18 $\rm
  {km\,s}^{-1}$, possibly corresponding to turbulent plasma flows. Small
  red (blue) shifts, up to 1.8 (4.9) $\rm {km\,s}^{-1}$ were measured. The
  intensity ratio of Si IV 1393.76 Å and Si IV 1402.77 Å confirmed that
  plasma was optically thin to Si IV (where the ratio = 2) during the
  impulsive phase of the flare in locations where strong H<SUB>2</SUB>
  emission was observed. In contrast, the ratio differs from optically
  thin value of 2 in parts of ribbons, indicating a role for opacity
  effects. A strong spatial and temporal correlation between H<SUB>2</SUB>
  and Si IV emission was evident supporting the notion that fluorescent
  excitation is responsible.

---------------------------------------------------------
Title: The science enabled by a dedicated solar system space telescope
Authors: Young, Cindy; Wong, M. H.; Sayanagi, K. M.; Curry, S.;
   Jessup, K. L.; Becker, T.; Hendrix, A.; Chanover, N.; Milam, S.;
   Holler, B. J.; Holsclaw, G.; Peralta, J.; Clarke, J.; Spencer, J.;
   Kelley, M. S. P.; Luhmann, J.; MacDonnell, D.; Vervack, R. J., Jr.;
   Rutherford, K.; Fletcher, L. N.; de Pater, I.; Vilas, F.; Feaga,
   L.; Siegmund, O.; Bell, J.; Delory, G.; Pitman, J.; Greathouse, T.;
   Wishnow, E.; Schneider, N.; Lillis, R.; Colwell, J.; Bowman, L.; Lopes,
   R. M. C.; McGrath, M.; Marchis, F.; Cartwright, R.; Poston, M. J.
2021BAAS...53d.232Y    Altcode: 2021psad.rept..232Y
  We advocate for a large/medium-class space telescope dedicated to
  planetary science to transform our understanding of time-dependent
  phenomena &amp; enable a comprehensive survey &amp; spectral
  characterization of minor bodies across the solar system. The key
  science questions &amp; themes presented here cannot fully be addressed
  using astrophysical assets.

---------------------------------------------------------
Title: On the clouds and ammonia in Jupiter's upper troposphere from
    Juno JIRAM reflectivity observations
Authors: Grassi, Davide; Mura, A.; Sindoni, G.; Adriani, A.; Atreya,
   S. K.; Filacchione, G.; Fletcher, L. N.; Lunine, J. I.; Moriconi,
   M. L.; Noschese, R.; Orton, G. S.; Plainaki, C.; Sordini, R.; Tosi, F.;
   Turrini, D.; Olivieri, A.; Eichstädt, G.; Hansen, C. J.; Melin, H.;
   Altieri, F.; Cicchetti, A.; Dinelli, B. M.; Migliorini, A.; Piccioni,
   G.; Stefani, S.; Bolton, S. J.
2021MNRAS.503.4892G    Altcode: 2021MNRAS.tmp..746G
  We analyse spectra measured by the Jovian Infrared Auroral Mapper
  (JIRAM, a payload element of the NASA Juno mission) in the 3150-4910
  cm<SUP>-1</SUP> (2.0-3.2 μm) range during the perijiove passage of 2016
  August. Despite modelling uncertainties, the quality and the relative
  uniformity of the data set allow us to determine several parameters
  characterizing the Jupiter's upper troposphere in the latitude range
  of 35°S-30°N. Ammonia relative humidity at 500 millibars varies
  between 5 per cent to supersaturation beyond 100 per cent for about
  3 per cent of the processed spectra. Ammonia appears depleted over
  belts and relatively enhanced over zones. Local variations of ammonia,
  arguably associated with local dynamics, are found to occur in several
  locations on the planet (Oval BA, South Equatorial Belt). Cloud
  altitude, defined as the level where aerosol opacity reaches unit
  value at 3650 cm<SUP>-1</SUP> (2.74 μm), is maximum over the Great
  Red Spot (&gt;20 km above the 1 bar level) and the zones (15 km),
  while it decreases over the belts and towards higher latitudes. The
  aerosol opacity scale height suggests more compact clouds over zones
  and more diffuse clouds over belts. The integrated opacity of clouds
  above the 1.3-bar pressure level is found to be minimum in regions
  where thermal emission of the deeper atmosphere is maximum. The
  opacity of tropospheric haze above the 200-mbar level also increases
  over zones. Our results are consistent with a Hadley-type circulation
  scheme previously proposed in literature for belts and zones, with
  clear hemisphere asymmetries in cloud and haze.

---------------------------------------------------------
Title: The effect of a solar flare on chromospheric oscillations
Authors: Millar, David C. L.; Fletcher, Lyndsay; Milligan, Ryan O.
2021MNRAS.503.2444M    Altcode: 2021MNRAS.tmp..652M; 2020arXiv200710301M
  Oscillations in the solar atmosphere have long been observed both in
  quiet conditions and during solar flares. The chromosphere is known
  for its 3-min signals, which are strong over sunspot umbrae, and have
  periods determined by the chromosphere's acoustic cut-off frequency. A
  small number of observations have shown the chromospheric signals to
  be affected by energetic events such as solar flares, however the link
  between flare activity and these oscillations remains unclear. In this
  work, we present evidence of changes to the oscillatory structure of
  the chromosphere over a sunspot which occurs during the impulsive
  phase of an M1 flare. Using imaging data from the CRISP instrument
  across the H α and Ca II 8542 Å spectral lines, we employed a method
  of fitting models to power spectra to produce maps of where there is
  evidence of oscillatory signals above a red-noise background. Comparing
  results taken before and after the impulsive phase of the flare, we
  found that the oscillatory signals taken after the start of the flare
  differ in two ways: the locations of oscillatory signals had changed
  and the typical periods of the oscillations had tended to increase
  (in some cases increasing from &lt;100 s to ∼200 s). Both of these
  results can be explained by a restructuring of the magnetic field in
  the chromosphere during the flare activity, which is backed up by images
  of coronal loops showing clear changes to magnetic connectivity. These
  results represent one of the many ways that active regions can be
  affected by solar flares.

---------------------------------------------------------
Title: Critical Science Plan for the Daniel K. Inouye Solar Telescope
    (DKIST)
Authors: Rast, Mark P.; Bello González, Nazaret; Bellot Rubio,
   Luis; Cao, Wenda; Cauzzi, Gianna; Deluca, Edward; de Pontieu, Bart;
   Fletcher, Lyndsay; Gibson, Sarah E.; Judge, Philip G.; Katsukawa,
   Yukio; Kazachenko, Maria D.; Khomenko, Elena; Landi, Enrico; Martínez
   Pillet, Valentín; Petrie, Gordon J. D.; Qiu, Jiong; Rachmeler,
   Laurel A.; Rempel, Matthias; Schmidt, Wolfgang; Scullion, Eamon; Sun,
   Xudong; Welsch, Brian T.; Andretta, Vincenzo; Antolin, Patrick; Ayres,
   Thomas R.; Balasubramaniam, K. S.; Ballai, Istvan; Berger, Thomas E.;
   Bradshaw, Stephen J.; Campbell, Ryan J.; Carlsson, Mats; Casini,
   Roberto; Centeno, Rebecca; Cranmer, Steven R.; Criscuoli, Serena;
   Deforest, Craig; Deng, Yuanyong; Erdélyi, Robertus; Fedun, Viktor;
   Fischer, Catherine E.; González Manrique, Sergio J.; Hahn, Michael;
   Harra, Louise; Henriques, Vasco M. J.; Hurlburt, Neal E.; Jaeggli,
   Sarah; Jafarzadeh, Shahin; Jain, Rekha; Jefferies, Stuart M.; Keys,
   Peter H.; Kowalski, Adam F.; Kuckein, Christoph; Kuhn, Jeffrey R.;
   Kuridze, David; Liu, Jiajia; Liu, Wei; Longcope, Dana; Mathioudakis,
   Mihalis; McAteer, R. T. James; McIntosh, Scott W.; McKenzie, David
   E.; Miralles, Mari Paz; Morton, Richard J.; Muglach, Karin; Nelson,
   Chris J.; Panesar, Navdeep K.; Parenti, Susanna; Parnell, Clare E.;
   Poduval, Bala; Reardon, Kevin P.; Reep, Jeffrey W.; Schad, Thomas A.;
   Schmit, Donald; Sharma, Rahul; Socas-Navarro, Hector; Srivastava,
   Abhishek K.; Sterling, Alphonse C.; Suematsu, Yoshinori; Tarr, Lucas
   A.; Tiwari, Sanjiv; Tritschler, Alexandra; Verth, Gary; Vourlidas,
   Angelos; Wang, Haimin; Wang, Yi-Ming; NSO and DKIST Project; DKIST
   Instrument Scientists; DKIST Science Working Group; DKIST Critical
   Science Plan Community
2021SoPh..296...70R    Altcode: 2020arXiv200808203R
  The National Science Foundation's Daniel K. Inouye Solar Telescope
  (DKIST) will revolutionize our ability to measure, understand,
  and model the basic physical processes that control the structure
  and dynamics of the Sun and its atmosphere. The first-light DKIST
  images, released publicly on 29 January 2020, only hint at the
  extraordinary capabilities that will accompany full commissioning of
  the five facility instruments. With this Critical Science Plan (CSP)
  we attempt to anticipate some of what those capabilities will enable,
  providing a snapshot of some of the scientific pursuits that the DKIST
  hopes to engage as start-of-operations nears. The work builds on the
  combined contributions of the DKIST Science Working Group (SWG) and
  CSP Community members, who generously shared their experiences, plans,
  knowledge, and dreams. Discussion is primarily focused on those issues
  to which DKIST will uniquely contribute.

---------------------------------------------------------
Title: Carrington's lost photograph
Authors: Cliver, E. W.; Fletcher, Lyndsay; Hudson, H. S.
2021A&G....62.2.40C    Altcode:
  Ed Cliver, Lyndsay Fletcher and Hugh Hudson are looking for a photograph
  of Richard Carrington. Can you help?

---------------------------------------------------------
Title: Compositional Mapping of Europa and Ganymede with VLT/SPHERE
    and Galileo/NIMS Using Markov Chain Monte Carlo Fitting
Authors: King, O. R. T.; Fletcher, L. N.
2021LPI....52.1060K    Altcode:
  Infrared spectral observations of Europa and Ganymede from VLT/SPHERE
  and Galileo/NIMS have been fit using a Monte Carlo model to calculate
  compositional abundances and uncertainties.

---------------------------------------------------------
Title: A machine-learning approach to correcting atmospheric seeing
    in solar flare observations
Authors: Armstrong, John A.; Fletcher, Lyndsay
2021MNRAS.501.2647A    Altcode: 2020arXiv201112814A; 2020MNRAS.tmp.3530A
  Current post-processing techniques for the correction of atmospheric
  seeing in solar observations - such as Speckle interferometry and
  Phase Diversity methods - have limitations when it comes to their
  reconstructive capabilities of solar flare observations. This,
  combined with the sporadic nature of flares meaning observers cannot
  wait until seeing conditions are optimal before taking measurements,
  means that many ground-based solar flare observations are marred with
  bad seeing. To combat this, we propose a method for dedicated flare
  seeing correction based on training a deep neural network to learn
  to correct artificial seeing from flare observations taken during
  good seeing conditions. This model uses transfer learning, a novel
  technique in solar physics, to help learn these corrections. Transfer
  learning is when another network already trained on similar data
  is used to influence the learning of the new network. Once trained,
  the model has been applied to two flare data sets: one from AR12157 on
  2014 September 6 and one from AR12673 on 2017 September 6. The results
  show good corrections to images with bad seeing with a relative error
  assigned to the estimate based on the performance of the model. Further
  discussion takes place of improvements to the robustness of the error
  on these estimates.

---------------------------------------------------------
Title: Hot X-ray onsets of solar flares
Authors: Hudson, Hugh S.; Simões, Paulo J. A.; Fletcher, Lyndsay;
   Hayes, Laura A.; Hannah, Iain G.
2021MNRAS.501.1273H    Altcode: 2020MNRAS.tmp.3462H; 2020arXiv200705310H
  The study of the localized plasma conditions before the impulsive phase
  of a solar flare can help us understand the physical processes that
  occur leading up to the main flare energy release. Here, we present
  evidence of a hot X-ray 'onset' interval of enhanced isothermal plasma
  temperatures in the range of 10-15 MK over a period of time prior to
  the flare's impulsive phase. This 'hot onset' interval occurs during
  the initial soft X-ray increase and definitely before any detectable
  hard X-ray emission. The isothermal temperatures, estimated by the
  Geostationary Operational Environmental Satellite X-ray sensor,
  and confirmed with data from the Reuven Ramaty High Energy Solar
  Spectroscopic Imager, show no signs of gradual increase, and the
  'hot onset' phenomenon occurs regardless of flare classification or
  configuration. In a small sample of four representative flare events, we
  tentatively identify this early hot onset soft X-ray emission to occur
  within footpoint and low-lying loop regions, rather than in coronal
  structures, based on images from the Atmospheric Imaging Assembly. We
  confirm this via limb occultation of a flaring region. These hot
  X-ray onsets appear before there is evidence of collisional heating
  by non-thermal electrons, and hence challenge the standard modelling
  techniques.

---------------------------------------------------------
Title: Measuring the structure and equation of state of polyethylene
    terephthalate at megabar pressures
Authors: Lütgert, J.; Vorberger, J.; Hartley, N. J.; Voigt, K.;
   Rödel, M.; Schuster, A. K.; Benuzzi-Mounaix, A.; Brown, S.; Cowan,
   T. E.; Cunningham, E.; Döppner, T.; Falcone, R. W.; Fletcher, L. B.;
   Galtier, E.; Glenzer, S. H.; Laso Garcia, A.; Gericke, D. O.; Heimann,
   P. A.; Lee, H. J.; McBride, E. E.; Pelka, A.; Prencipe, I.; Saunders,
   A. M.; Schölmerich, M.; Schörner, M.; Sun, P.; Vinci, T.; Ravasio,
   A.; Kraus, D.
2021NatSR..1112883L    Altcode:
  We present structure and equation of state (EOS) measurements
  of biaxially orientated polyethylene terephthalate (PET,
  (<SUB>C1<SUB>0</SUB>H<SUB>8</SUB>O<SUB>4</SUB>) n</SUB>?, also called
  mylar) shock-compressed to (155 ±20 ?) GPa and (6000 ±1000 ?) K
  using in situ X-ray diffraction, Doppler velocimetry, and optical
  pyrometry. Comparing to density functional theory molecular dynamics
  (DFT-MD) simulations, we find a highly correlated liquid at conditions
  differing from predictions by some equations of state tables,
  which underlines the influence of complex chemical interactions
  in this regime. EOS calculations from ab initio DFT-MD simulations
  and shock Hugoniot measurements of density, pressure and temperature
  confirm the discrepancy to these tables and present an experimentally
  benchmarked correction to the description of PET as an exemplary
  material to represent the mixture of light elements at planetary
  interior conditions.

---------------------------------------------------------
Title: Constraints on the height of the CH<SUB>4</SUB> homopause
    from an analysis of IRTF-TEXES spectra
Authors: Sinclair, J. A.; Greathouse, T. K.; Giles, R.; Antuñano,
   A.; Moses, J. I.; Fouchet, T.; Bezard, B.; Clark, G. B.; Tao, C.;
   Grodent, D. C.; Orton, G.; Hue, V.; Fletcher, L. N.; Irwin, P. G.
2020AGUFMA076...03S    Altcode:
  We present an analysis of high-resolution spectra of Jupiter's
  CH<SUB>3</SUB> (methyl radical) and CH<SUB>4</SUB> emission measured at
  mid-to-high latitudes with the goal of determining spatial and temporal
  variations in the altitude of the CH<SUB>4</SUB> homopause. IRTF-TEXES
  (Texas Echelon Cross Echelle Spectrograph, Lacy et al., 2002, PASP
  114, 153-168) spectra were measured on April 16<SUP>th</SUP> and
  August 20<SUP>th</SUP> 2019 and were inverted as follows. A family of
  photochemical models, based on Moses &amp; Poppe (2017, Icarus 297,
  33-58), was computed by varying the eddy diffusion coefficient in
  the upper stratosphere and thereby increasing the altitude of the
  CH<SUB>4</SUB> homopause. Adopting each photochemical model in turn,
  the emission features of CH<SUB>3</SUB> and CH<SUB>4</SUB> were modeled
  simultaneously by allowing the vertical temperature profile to vary,
  and the quality of fit to the observations was used to discriminate
  between models. In preliminary results of August 20<SUP>th</SUP>
  2019 spectra, we find that a CH<SUB>4</SUB> homopause altitude below
  ~350 km (with respect to 1 bar) is required to fit the observations
  equatorward of the main oval. At 68°N, 180°W (planetocentric, System
  III), the center of the northern auroral region, a homopause altitude
  of ~450 km optimized the fit to the spectra. At 68°N, but sampling
  longitudes outside the main oval, a homopause altitude between ~336
  km and ~400 km was required to fit the spectra. Our results confirm
  the hypothesis presented in previous work (e.g. Clark et al., 2018,
  JGR 123, 7554-7567) that the CH<SUB>4</SUB> homopause altitude is
  higher in Jupiter's auroral regions compared to elsewhere on the
  planet. This suggests deposition of energy from the magnetosphere
  drives turbulence and vertical winds, which advects CH<SUB>4</SUB>
  and its photochemical by-products to higher altitudes. We will repeat
  this analysis for IRTF/TEXES and SOFIA/EXES observations scheduled
  near-contemporaneously with Juno's 29<SUP>th</SUP> perijove (September
  16th 2020) and search for temporal variations between measurements.

---------------------------------------------------------
Title: Modelling Optically Thick Radiation from Solar Flares with
    the Lightweaver Framework
Authors: Osborne, C.; Fletcher, L.
2020AGUFMSH0500002O    Altcode:
  Most spectral lines formed in the chromosphere present complex profiles
  due to their formation in optically thick regions and this is further
  exacerbated by the rapid variations of this layer during a flare. Whilst
  these lines carry a wealth of information regarding their formation
  conditions, this information is difficult to extract. The Lightweaver
  framework is flexible new software package for synthesising radiation
  from both plane-parallel and multi-dimensional atmospheres where the
  atomic populations can be out of local thermodynamic equilibrium. In
  addition to the more commonly solved statistical equilibrium equations,
  Lightweaver also provides tools to facilitate solving the problem of
  time-dependent level populations. This framework is an open source
  project designed to be used through Python and easily reconfigured
  to solve new problems. We have applied tools built on Lightweaver to
  reprocess simulations produced by the RADYN code, allowing further
  investigation into the effects of partial frequency redistribution, and
  calculation of response functions in this time dependent context. We
  expect that these new methods should provide additional diagnostic
  potential coinciding with observations from next generation telescopes
  such as DKIST. Lightweaver is also being used to investigate the effect
  of the radiation emitted from compact flare kernels on surrounding
  plasma, by extending this reprocessing to multi-dimensional radiative
  transfer. We will present the Lightweaver framework and discuss how
  it can easily be adapted to investigate these different phenomena as
  well as the initial results from these investigations.

---------------------------------------------------------
Title: SOFIA FORCAST observations of Jupiter in the JWST-era
Authors: De Pater, I.; Reach, W. T.; Fletcher, L. N.; Goullaud, C.;
   Wong, M. H.
2020AGUFMP056.0005D    Altcode:
  Jupiter, the most accessible example for the study of atmospheric
  circulation on a giant planet, serves as a template for our
  understanding of the atmospheric dynamics and chemistry of the
  ever-growing number of extrasolar planets. The atmospheres of
  giant planets are extremely active, varying on timescales ranging
  from decades (seasonally evolving chemistry and clouds), to months
  (variability of storms and banded structures) and even minutes (e.g.,
  asteroidal/cometary impacts and localized storm systems). These
  evolving atmospheres serve as natural planetary-scale laboratories
  for studying the fundamental meteorology, chemistry and evolutionary
  mechanisms that shape the worlds around us. SOFIA's remote sensing
  in the far-IR penetrates thick upper-tropospheric hazes to explore
  the complex, turbulent dynamics of Jupiter's weather layer. <P />In
  2014 we observed Jupiter with FORCAST at 17-37 micron to constrain the
  shape of its continuum emission (Fletcher et al., 2017, Ic. 286, 223),
  which can only be achieved if obscuration by telluric water vapor is
  minimized, i.e., from SOFIA or from space. The SOFIA data confirmed
  the Voyager findings in detecting an equator to pole increase in the
  para-H<SUB>2</SUB> fraction (f<SUB>p</SUB>), with low f<SUB>p</SUB>
  and sub-equilibrium conditions at the equator and high f<SUB>p</SUB>
  and super-equilibrium conditions polewards of 60°latitude. The
  para-H<SUB>2</SUB> fraction traces mean vertical mixing on timescales of
  years to decades, depending on the poorly-known hydrogen equilibration
  time in Jupiter's atmosphere. Equilibrium f<SUB>p</SUB> thus implies
  weak vertical mixing, while sub- or super-equilibrium fractions
  correspond to mean upwelling or subsidence, respectively (in the
  upper troposphere where f<SUB>p</SUB> is measured). Interestingly,
  both Voyager and SOFIA measured higher f<SUB>p</SUB> values at high
  northern latitudes than at high southern latitudes, suggesting an
  asymmetry between the two hemispheres where none is expected on the
  basis of seasonal variability. We discuss the advantages of a similar
  experiment simultaneously with JWST/ERS observations planned to be
  carried out after launch.

---------------------------------------------------------
Title: Hot Onsets of Solar Flares
Authors: Hudson, H. S.; Simoes, P. J. D. A.; Fletcher, L.; Hayes,
   L.; Hannah, I. G.
2020AGUFMSH0500003H    Altcode:
  No abstract at ADS

---------------------------------------------------------
Title: Atmospheric chemistry on Uranus and Neptune
Authors: Moses, J. I.; Cavalié, T.; Fletcher, L. N.; Roman, M. T.
2020RSPTA.37890477M    Altcode: 2020arXiv200611367M; 2020RSPTA.37800477M
  Comparatively little is known about atmospheric chemistry on Uranus and
  Neptune, because remote spectral observations of these cold, distant
  `Ice Giants' are challenging, and each planet has only been visited by
  a single spacecraft during brief flybys in the 1980s. Thermochemical
  equilibrium is expected to control the composition in the deeper, hotter
  regions of the atmosphere on both planets, but disequilibrium chemical
  processes such as transport-induced quenching and photochemistry alter
  the composition in the upper atmospheric regions that can be probed
  remotely. Surprising disparities in the abundance of disequilibrium
  chemical products between the two planets point to significant
  differences in atmospheric transport. The atmospheric composition of
  Uranus and Neptune can provide critical clues for unravelling details
  of planet formation and evolution, but only if it is fully understood
  how and why atmospheric constituents vary in a three-dimensional sense
  and how material coming in from outside the planet affects observed
  abundances. Future mission planning should take into account the key
  outstanding questions that remain unanswered about atmospheric chemistry
  on Uranus and Neptune, particularly those questions that pertain to
  planet formation and evolution, and those that address the complex,
  coupled atmospheric processes that operate on Ice Giants within our
  solar system and beyond. <P />This article is part of a discussion
  meeting issue `Future exploration of ice giant systems'.

---------------------------------------------------------
Title: The internal structure of Jupiter's Great Red Spot
Authors: Li, C.; Fletcher, L. N.; Wong, M. H.; Allison, M. D.; Atreya,
   S. K.; Bjoraker, G. L.; Bolton, S. J.; Guillot, T.; Ingersoll, A. P.;
   Janssen, M. A.; Levin, S.; Li, L.; Orton, G.; Oyafuso, F. A.; Steffes,
   P. G.; Zhang, Z.
2020AGUFMA076...15L    Altcode:
  Contrasts in thermal emission within and surrounding Jupiter's
  Great Red Spot (GRS) were mapped at six frequencies by the Juno
  Microwave Radiometer (MWR) during its 7<SUP>th</SUP> flyby (PJ7)
  over Jupiter. Compared to the average thermal emission at the other
  longitudes, the GRS appears brighter by about 22 K in the 0.6-GHz
  (50-cm) channel, which senses thermal emission from hundreds of bars in
  pressure. The brightness-temperature anomaly decreases with increasing
  altitude and almost vanishes at the 2.6-GHz (11.5-cm) channel, probing
  approximately the 10-bar pressure level. At levels shallower than 10
  bars, the GRS exhibits a brightness-temperature asymmetry in latitude,
  with thermal emission from the northern part of the GRS being fainter
  and the southern part being brighter by up to 10 K compared to the
  average. A novel way of exploring the degenerate space of temperature
  and opacity is developed by progressively increasing the constraint
  on the temperature profile. The result suggests that the GRS has
  an extended upwelling branch in the north between 20<SUP>o</SUP>S ~
  16<SUP>o</SUP>S originating at depths &gt; 100 bars (230 km down from
  the 1-bar level) and a narrow subsiding branch in the south near
  23.5<SUP>o</SUP>S penetrating to about 30 bars. We did not see the
  bottom of the GRS in our longest wavelength channel, which means that
  the bottom of the GRS must be deeper than 100 bars.

---------------------------------------------------------
Title: Thermal Measurements of the Ring System of Uranus
Authors: Molter, E. M.; De Pater, I.; Roman, M. T.; Fletcher, L. N.
2020AGUFMP017...03M    Altcode:
  The narrow main rings of Uranus are composed of primarily centimeter-
  to meter-sized particles, with a very small or nonexistent dust
  component. This property presents a challenge to visible and
  near-infrared instruments observing the rings, which are largely
  unable to differentiate large particles from dust; thus, the thickness,
  mass, filling factor, and detailed particle size distribution of these
  rings remain poorly constrained. In this work we observed the thermal
  component of the Uranian ring system for the first time, making use of
  millimeter (1.3-3.1 mm) imaging from the Atacama Large (sub-)Millimeter
  Array and mid-infrared imaging from the Very Large Telescope VISIR
  instrument. The ε ring was readily seen by eye in the images; the
  other main ring groups were visible in a radial (azimuthally-averaged)
  profile at millimeter wavelengths. A simple thermal model similar to the
  Near-Earth Asteroid Thermal Model (NEATM) of near-Earth asteroids was
  leveraged to determine a ring particle temperature of 77.3 ± 1.8 K for
  the ε ring. This temperature is higher than expected for fast-rotating
  ring particles viewed at our observing geometry, meaning that the data
  favor a model in which the thermal inertia of the ring particles is
  low and/or their rotation rate is slow. The ε ring displayed a factor
  of 2-3 brightness difference between periapsis and apoapsis, and an
  average fractional visible area (the two-dimensional projection of the
  filling factor) of 49.1% ± 2.2%. These observations are consistent with
  optical and near-infrared reflected light observations, confirming the
  hypothesis that micron-sized dust is not present in Uranus's main rings.

---------------------------------------------------------
Title: Long-term Cycles of Variability of Jupiter's Atmosphere from
    Ground-based Infrared Observations
Authors: Antuñano, A.; Fletcher, L. N.; Orton, G.; Sinclair, J. A.;
   Kasaba, Y.
2020AGUFMA076...06A    Altcode:
  Jupiter's atmosphere displays some of the most dramatic weather of
  any planet in our Solar System, with cycles of activity changing the
  upper tropospheric and stratospheric temperatures, aerosols, and
  cloud structures through physical processes that are not yet well
  understood. Here we use almost 40 years (more than 3 jovian years)
  of ground-based infrared observations captured at NASA's Infrared
  Telescope Facility (IRTF), the Very Large Telescope (VLT) and Subaru
  between 1980 and 2019 in a number of filters spanning from 7.9 to
  24.5 µm (sampling upper tropospheric and stratospheric temperatures
  and aerosols via collision-induced hydrogen and helium absorption, and
  emission from stratospheric hydrocarbons), to (i) understand the impact
  of the tropospheric activity on the periodicity of the stratospheric
  temperature oscillations, (ii) characterize the long-term variability of
  Jupiter's atmosphere at different altitudes in the upper troposphere
  and stratosphere, and (iii) investigate the long-term thermal,
  chemical and aerosol changes in Jupiter's troposphere. In particular,
  we generate Lomb-Scargle periodograms and apply a Wavelet Transform
  analysis to our dataset to look for potential periodicities on the
  brightness temperature variability in different filters and compare
  them to previously reported cyclic activity at visible wavelengths
  (sensing the ammonia cloud top at ~500 mbar) and 5 µm (sensing the
  1-4 bar pressure level). Finally, a Principal Component Analyses
  (PCA) is also performed to analyse the correlation of the brightness
  temperature variations at different belts and zones.

---------------------------------------------------------
Title: Saturn's Seasonal Atmosphere at Northern Summer Solstice
Authors: Fletcher, L. N.; Sromovsky, L.; Hue, V.; Moses, J. I.;
   Guerlet, S.; West, R. A.; Koskinen, T.
2020arXiv201209288F    Altcode:
  The incredible longevity of Cassini's orbital mission at Saturn has
  provided the most comprehensive exploration of a seasonal giant planet
  to date. This review explores Saturn's changing global temperatures,
  composition, and aerosol properties between northern spring and
  summer solstice (2015-2017), extending our previous review of
  Cassini's remote sensing investigations (2004-14, Fletcher et al.,
  2018) to the grand finale. The result is an unprecedented record
  of Saturn's climate that spans almost half a Saturnian year, which
  can be used to test the seasonal predictions of radiative climate
  models, neutral and ion photochemistry models, and atmospheric
  circulation models. Hemispheric asymmetries in tropospheric and
  stratospheric temperatures were observed to reverse from northern
  winter to northern summer; spatial distributions of hydrocarbons
  and para-hydrogen shifted in response to atmospheric dynamics
  (e.g., seasonally-reversing Hadley cells, polar stratospheric vortex
  formation, equatorial stratospheric oscillations, and inter-hemispheric
  transport); and upper tropospheric and stratospheric aerosols exhibited
  changes in optical thickness that modulated Saturn's visible colours
  (from blue hues to a golden appearance in the north near solstice),
  reflectivity, and near-infrared emission. Numerical simulations of
  radiative balance and photochemistry do a good job in reproducing the
  observed seasonal change and phase lags, but discrepancies between
  models and observations still persist, indicating a crucial role for
  atmospheric dynamics and the need to couple chemical and radiative
  schemes to the next generation of circulation models. With Cassini's
  demise, an extended study of Saturn's seasons, from northern summer
  to autumn, will require the capabilities of ground- and space-based
  observatories, as we eagerly await the next orbital explorer at Saturn.

---------------------------------------------------------
Title: Determining the Global Water Abundance in Jupiter from Juno MWR
Authors: Zhang, Z.; Levin, S.; Adumitroaie, V.; Allison, M. D.;
   Arballo, J. K.; Atreya, S. K.; Becker, H. N.; Bjoraker, G. L.;
   Bolton, S. J.; Brown, S. T.; Fletcher, L. N.; Guillot, T.; Gulkis,
   S.; Hodges, A. L.; Ingersoll, A. P.; Janssen, M. A.; Li, C.; Li, L.;
   Lunine, J. I.; Misra, S.; Orton, G.; Oyafuso, F. A.; Santos-Costa,
   D.; Sarkissian, E.; Steffes, P. G.; Waite, H., Jr.; Wong, M. H.
2020AGUFMP005.0005Z    Altcode:
  The global water abundance in Jupiter is pivotal in understanding
  Giant-Planet formation and the delivery of volatiles throughout the
  solar system. The Microwave Radiometer (MWR) on board Juno provides
  the first measurements of Jupiter's deep atmosphere, down to ~250 bars
  in pressure. Li et al. (2020) reported the initial results from MWR
  on water abundance near Jupiter's equatorial region. The discovery by
  Juno that Jupiter's atmosphere is not well mixed at depth and displays
  significant variability with latitude suggests that water may vary
  with latitude even at depth. We present current plans and status for
  Juno's investigation of water beyond equatorial latitudes including
  observation plans for Juno's extended mission that will be able to
  observe Jupiter's north polar region at improved resolution.

---------------------------------------------------------
Title: Ice giant system exploration in the 2020s: an introduction
Authors: Fletcher, L. N.; Simon, A. A.; Hofstadter, M. D.; Arridge,
   C. S.; Cohen, Ian J.; Masters, A.; Mandt, K.; Coustenis, A.
2020RSPTA.37890473F    Altcode: 2020RSPTA.37800473F; 2020arXiv200812125F
  The international planetary science community met in London in
  January 2020, united in the goal of realizing the first dedicated
  robotic mission to the distant ice giants, Uranus and Neptune, as the
  only major class of solar system planet yet to be comprehensively
  explored. Ice-giant-sized worlds appear to be a common outcome of
  the planet formation process, and pose unique and extreme tests to
  our understanding of exotic water-rich planetary interiors, dynamic
  and frigid atmospheres, complex magnetospheric configurations,
  geologically-rich icy satellites (both natural and captured), and
  delicate planetary rings. This article introduces a special issue on
  ice giant system exploration at the start of the 2020s. We review
  the scientific potential and existing mission design concepts for
  an ambitious international partnership for exploring Uranus and/or
  Neptune in the coming decades. <P />This article is part of a discussion
  meeting issue `Future exploration of ice giant systems'.

---------------------------------------------------------
Title: Slowly Moving Thermal Waves in Saturn
Authors: Orton, G.; Sinclair, J.; Fletcher, L.; Read, P.; Flasar,
   F. M.; Achterberg, R.; Yanamandra-Fisher, P.; Fujiyoshi, T.; Fisher,
   B.; Irwin, P.
2020DPS....5220104O    Altcode:
  We surveyed the global temperature field of Saturn's atmosphere
  using the Cassini Composite Infrared Spectrometer (CIRS, 7-1000 µm),
  complemented by ground-based mid-infrared observations (7-25 µm),
  from 1995 to 2020. We detected and characterized properties of slowly
  moving zonal thermal waves and their variability during that period. The
  most inclusive CIRS surveys, FIRMAPs (15 cm<SUP>-1</SUP> spectral
  resolution), covered the planet from the equator to either north or
  south pole, sweeping through the latitude range while the planet rotated
  beneath over its ~10-hour rotation. Additional measurements were made by
  ground-based observations at the Infrared Telescope Facility using the
  MIRSI instrument, the Very Large Telescope using VISIR and the Subaru
  Telescope using COMICS. We sampled spectral ranges dominated both by
  upper-tropospheric emission (80-200 mbar) and by stratospheric emission
  (0.5-3 mbar). Several types of slowly moving zonal thermal waves were
  detected: (1) meridionally broad wavenumber-1 through -3 oscillations,
  (2) equatorial waves, some of which extend northward to mid-latitudes,
  (3) prominent wavenumber-12 oscillations in the southern hemisphere,
  which also have components of wavenumbers 1 through 3 and extend over
  15°-35°S latitude, (4) mid-latitude wavenumber &gt; 2 oscillations
  in both hemispheres with variable time dependence and morphology,
  and (5) discrete low-latitude tropospheric features. The prominent
  southern-hemisphere waves appear to have distinct periods of maximum
  intensity around 2003-2004 from ground-based observations and 2008-2009
  from CIRS FIRMAPs. These waves are easily detectable in both the
  stratosphere, where the other types of waves are prominent, but also
  in the troposphere with no detectable phase shift in longitude. These
  waves were also sufficiently coherent to track a mean phase speed,
  which is about 0.5° per day, retrograde. After 2009, wavenumber-1
  oscillations in the northern hemisphere are joined by higher-wavenumber
  oscillations. A local temperature maximum is seen around 2010-2011,
  then another in 2016-2017. Further ground-based observations are
  required to determine whether the amplitude of northern-hemisphere
  waves is influenced by seasonally dependent insolation.

---------------------------------------------------------
Title: The Solar Orbiter magnetometer
Authors: Horbury, T. S.; O'Brien, H.; Carrasco Blazquez, I.; Bendyk,
   M.; Brown, P.; Hudson, R.; Evans, V.; Oddy, T. M.; Carr, C. M.; Beek,
   T. J.; Cupido, E.; Bhattacharya, S.; Dominguez, J. -A.; Matthews, L.;
   Myklebust, V. R.; Whiteside, B.; Bale, S. D.; Baumjohann, W.; Burgess,
   D.; Carbone, V.; Cargill, P.; Eastwood, J.; Erdös, G.; Fletcher,
   L.; Forsyth, R.; Giacalone, J.; Glassmeier, K. -H.; Goldstein, M. L.;
   Hoeksema, T.; Lockwood, M.; Magnes, W.; Maksimovic, M.; Marsch, E.;
   Matthaeus, W. H.; Murphy, N.; Nakariakov, V. M.; Owen, C. J.; Owens,
   M.; Rodriguez-Pacheco, J.; Richter, I.; Riley, P.; Russell, C. T.;
   Schwartz, S.; Vainio, R.; Velli, M.; Vennerstrom, S.; Walsh, R.;
   Wimmer-Schweingruber, R. F.; Zank, G.; Müller, D.; Zouganelis, I.;
   Walsh, A. P.
2020A&A...642A...9H    Altcode:
  The magnetometer instrument on the Solar Orbiter mission is designed
  to measure the magnetic field local to the spacecraft continuously
  for the entire mission duration. The need to characterise not only
  the background magnetic field but also its variations on scales from
  far above to well below the proton gyroscale result in challenging
  requirements on stability, precision, and noise, as well as magnetic
  and operational limitations on both the spacecraft and other
  instruments. The challenging vibration and thermal environment has
  led to significant development of the mechanical sensor design. The
  overall instrument design, performance, data products, and operational
  strategy are described.

---------------------------------------------------------
Title: Reflection and Shadowing from Saturn's Rings: Influence on
    Photochemisty and Heating
Authors: Edgington, S. G.; Atreya, S.; West, R.; Baines, K.;
   Fletcher, L.
2020DPS....5220106E    Altcode:
  Cassini orbited Saturn for over thirteen years, nearly a half Saturn
  year. This corresponded to a seasonal configuration where the sub-solar
  point was at ~24°S at the time of Saturn Orbit Insertion (July 1, 2004)
  and ~27°N at the time of Cassini's Grand Finale. During this period,
  the ring shadow moved southward from covering a substantial area of
  the northern hemisphere to covering a large swath of territory south
  of the equator as solstice approached. At equinox, the rings project
  a small sliver of shadow at low latitudes. At its maximum extent, the
  ring shadow can reach as far as 48°N/S at the meridian (~58°N/S at the
  terminator). <P />Both ultraviolet and visible sunlight penetrating into
  any particular latitude will vary greatly depending on both Saturn's
  season, the optical thickness of each ring system and its reflective
  properties. In essence, the rings act like both semi-transparent
  Venetian blinds over the atmosphere of Saturn. At the same time, the
  illuminated side of the rings reflect ultraviolet and visible solar
  photons onto the fully illuminated hemisphere of the planet. This acts
  to enhance both photochemistry and heating and potentially enhancing
  seasonal effects. Lastly, the rings, having a temperature themselves,
  provides a source of thermal photons impinging onto the atmosphere and
  a possible source of heating. <P />The projection of the oscillating
  ring shadow onto the planet has been derived as a function of season. In
  addition, detailed calculations of geometric parameters important for
  light scattering from the rings onto an oblate planet have been worked
  for a fine grid of latitudes and longitudes. We will focus on how these
  geometric parameters can be used for both photochemical (UV) and thermal
  balance (visible and infrared) radiative transfer calculations as a
  function of season. <P />The impact of these augmentations on production
  and loss rates of hydrocarbons (e.g. acetylene, ethane, and propane),
  ammonia, phosphine, and hazes will be examined and attempt to explain
  several Saturn observations conducted by Cassini. Comparison with
  Jupiter, where seasonal effects are known to be insignificant, will
  be made. <P />Acknowledgements: The research described in this paper
  was carried out in part at the Jet Propulsion Laboratory, California
  Institute of Technology, under a contract with the National Aeronautics
  and Space Administration. Government sponsorship is acknowledged.

---------------------------------------------------------
Title: Solar Flare Energy Partitioning and Transport -- the Impulsive
    Phase (a Heliophysics 2050 White Paper)
Authors: Kerr, Graham S.; Alaoui, Meriem; Allred, Joel C.; Bian,
   Nicholas H.; Dennis, Brian R.; Emslie, A. Gordon; Fletcher, Lyndsay;
   Guidoni, Silvina; Hayes, Laura A.; Holman, Gordon D.; Hudson, Hugh
   S.; Karpen, Judith T.; Kowalski, Adam F.; Milligan, Ryan O.; Polito,
   Vanessa; Qiu, Jiong; Ryan, Daniel F.
2020arXiv200908400K    Altcode:
  Solar flares are a fundamental component of solar eruptive events (SEEs;
  along with solar energetic particles, SEPs, and coronal mass ejections,
  CMEs). Flares are the first component of the SEE to impact our
  atmosphere, which can set the stage for the arrival of the associated
  SEPs and CME. Magnetic reconnection drives SEEs by restructuring the
  solar coronal magnetic field, liberating a tremendous amount of energy
  which is partitioned into various physical manifestations: particle
  acceleration, mass and magnetic-field eruption, atmospheric heating,
  and the subsequent emission of radiation as solar flares. To explain
  and ultimately predict these geoeffective events, the heliophysics
  community requires a comprehensive understanding of the processes that
  transform and distribute stored magnetic energy into other forms,
  including the broadband radiative enhancement that characterises
  flares. This white paper, submitted to the Heliophysics 2050 Workshop,
  discusses the flare impulsive phase part of SEEs, setting out the
  questions that need addressing via a combination of theoretical,
  modelling, and observational research. In short, by 2050 we must
  determine the mechanisms of particle acceleration and propagation,
  and must push beyond the paradigm of energy transport via nonthermal
  electron beams, to also account for accelerated protons &amp; ions
  and downward directed Alfven waves.

---------------------------------------------------------
Title: Solar Flare Energy Partitioning and Transport -- the Gradual
    Phase (a Heliophysics 2050 White Paper)
Authors: Kerr, Graham S.; Alaoui, Meriem; Allred, Joel C.; Bian,
   Nicholas H.; Dennis, Brian R.; Emslie, A. Gordon; Fletcher, Lyndsay;
   Guidoni, Silvina; Hayes, Laura A.; Holman, Gordon D.; Hudson, Hugh
   S.; Karpen, Judith T.; Kowalski, Adam F.; Milligan, Ryan O.; Polito,
   Vanessa; Qiu, Jiong; Ryan, Daniel F.
2020arXiv200908407K    Altcode:
  Solar flares are a fundamental component of solar eruptive events
  (SEEs; along with solar energetic particles, SEPs, and coronal
  mass ejections, CMEs). Flares are the first component of the SEE
  to impact our atmosphere, which can set the stage for the arrival
  of the associated SEPs and CME. Magnetic reconnection drives SEEs
  by restructuring the solar coronal magnetic field, liberating a
  tremendous amount of energy which is partitioned into various physical
  manifestations: particle acceleration, mass and magnetic-field eruption,
  atmospheric heating, and the subsequent emission of radiation as solar
  flares. To explain and ultimately predict these geoeffective events,
  the heliophysics community requires a comprehensive understanding of
  the processes that transform and distribute stored magnetic energy
  into other forms, including the broadband radiative enhancement that
  characterises flares. This white paper, submitted to the Heliophysics
  2050 Workshop, discusses the flare gradual phase part of SEEs, setting
  out the questions that need addressing via a combination of theoretical,
  modelling, and observational research. In short, the flare gradual phase
  persists much longer than predicted so, by 2050, we must identify the
  characteristics of the significant energy deposition sustaining the
  gradual phase, and address the fundamental processes of turbulence
  and non-local heat flux.

---------------------------------------------------------
Title: Hot X-ray Onsets of Solar Flares
Authors: Hayes, L.; Hudson, H.; Simoes, P.; Fletcher, L.; Hannah, I.
2020SPD....5121113H    Altcode:
  The study of the localized plasma conditions before the impulsive phase
  of a solar flare can help us understand the physical processes that
  occur leading up to the main flare energy release. Here, we present
  evidence of a hot X-ray 'onset' interval of enhanced isothermal plasma
  temperatures in the range of 10-15 MK up to tens of seconds prior
  to the flare's impulsive phase. This 'hot onset' interval occurs
  during the pre-flare time during which elevated GOES soft X-ray
  flux is detected, but prior to detectable hard X-ray emission. The
  isothermal temperatures, estimated by the Geostationary Operational
  Environmental Satellite (GOES) X-ray sensor, and confirmed with data
  from RHESSI, show no signs of gradual increase, and occurs regardless
  of flare classification or configuration. In a small sample of four
  representative flare events we identify this early hot onset soft
  X-ray emission mainly within footpoint and low-lying loops, rather
  than with coronal structures, based on images from the Atmospheric
  Imaging Assembly (AIA) and the use of limb occultation. These hot
  X-ray onsets appear before there is evidence of collisional heating by
  non-thermal electrons, and hence challenges the standard flare heating
  modeling techniques.

---------------------------------------------------------
Title: Jupiter's Equatorial Plumes and Hot Spots: Spectral Mapping
    from Gemini/TEXES and Juno/MWR
Authors: Fletcher, L. N.; Orton, G. S.; Greathouse, T. K.; Rogers,
   J. H.; Zhang, Z.; Oyafuso, F. A.; Eichstädt, G.; Melin, H.; Li, C.;
   Levin, S. M.; Bolton, S.; Janssen, M.; Mettig, H. -J.; Grassi, D.;
   Mura, A.; Adriani, A.
2020JGRE..12506399F    Altcode: 2020arXiv200400072F
  We present multiwavelength measurements of the thermal, chemical,
  and cloud contrasts associated with the visibly dark formations
  (also known as 5-μm hot spots) and intervening bright plumes
  on the boundary between Jupiter's Equatorial Zone (EZ) and North
  Equatorial Belt (NEB). Observations made by the TEXES 5- to 20-μm
  spectrometer at the Gemini North Telescope in March 2017 reveal the
  upper-tropospheric properties of 12 hot spots, which are directly
  compared to measurements by Juno using the microwave radiometer (MWR),
  JIRAM at 5 μm, and JunoCam visible images. MWR and thermal-infrared
  spectroscopic results are consistent near 0.7 bar. Mid-infrared-derived
  aerosol opacity is consistent with that inferred from visible-albedo
  and 5-μm opacity maps. Aerosol contrasts, the defining characteristics
  of the cloudy plumes and aerosol-depleted hot spots, are not a good
  proxy for microwave brightness. The hot spots are neither uniformly
  warmer nor ammonia-depleted compared to their surroundings at p&lt;1
  bar. At 0.7 bar, the microwave brightness at the edges of hot spots
  is comparable to other features within the NEB. Conversely, hot
  spots are brighter at 1.5 bar, signifying either warm temperatures
  and/or depleted NH<SUB>3</SUB> at depth. Temperatures and ammonia are
  spatially variable within the hot spots, so the precise location of
  the observations matters to their interpretation. Reflective plumes
  sometimes have enhanced NH<SUB>3</SUB>, cold temperatures, and elevated
  aerosol opacity, but each plume appears different. Neither plumes nor
  hot spots had microwave signatures in channels sensing p&gt;10 bars,
  suggesting that the hot spot/plume wave is a relatively shallow feature.

---------------------------------------------------------
Title: Spatial structure in Neptune's 7.90- μm stratospheric
    CH<SUB>4</SUB> emission, as measured by VLT-VISIR
Authors: Sinclair, J. A.; Orton, G. S.; Fletcher, L. N.; Roman, M.;
   de Pater, I.; Encrenaz, T.; Hammel, H. B.; Giles, R. S.; Velusamy,
   T.; Moses, J. I.; Irwin, P. G. J.; Momary, T. W.; Rowe-Gurney, N.;
   Tabataba-Vakili, F.
2020Icar..34513748S    Altcode:
  We present a comparison of VLT-VISIR images and Keck-NIRC2 images
  of Neptune, which highlight the coupling between its troposphere
  and stratosphere. VLT-VISIR images were obtained on September 16th
  2008 (UT) at 7.90 μm and 12.27 μm, which are primarily sensitive
  to 1-mbar CH<SUB>4</SUB> and C<SUB>2</SUB>H<SUB>6</SUB> emission,
  respectively. NIRC2 images in the H band were obtained on October 5th,
  6th and 9th 2008 (UT) and sense clouds and haze in the upper troposphere
  and lower stratosphere (from approximately 600 to 20 mbar). At 7.90 μm,
  we observe enhancements of CH<SUB>4</SUB> emission in latitude bands
  centered at approximately 25∘S and 48∘S (planetocentric). Within
  these zonal bands, tentative detections (&lt; 2 σ) of discrete
  hotspots of CH<SUB>4</SUB> emission are also evident at 24∘S,
  181∘W and 42∘S, 170∘W. The longitudinal-mean enhancements
  in the CH<SUB>4</SUB> emission are also latitudinally-coincident
  with bands of bright (presumably CH<SUB>4</SUB> ice) clouds in the
  upper troposphere and lower stratosphere evidenced in the H-band
  images. This suggests the Neptunian troposphere and stratosphere are
  coupled in these specific regions. This could be in the form of (1)
  'overshoot' of strong, upwelling plumes and advection of CH<SUB>4</SUB>
  ice into the lower stratosphere, which subsequently sublimates into
  CH<SUB>4</SUB> gas and/or (2) generation of waves by plumes impinging
  from the tropopause below, which impart their energy and heat the lower
  stratosphere. We favor the former process since there is no evidence
  of similar smaller-scale morphology in the C<SUB>2</SUB>H<SUB>6</SUB>
  emission, which probes a similar atmospheric level. However, we
  cannot exclude temperature variations as the source of the morphology
  observed in CH<SUB>4</SUB> emission. Future, near-infrared imaging of
  Neptune performed near-simultaneously with future mid-infrared spectral
  observations of Neptune by the James Webb Space Telescope would allow
  the coupling of Neptune's troposphere and stratosphere to be confirmed
  and studied in greater detail.

---------------------------------------------------------
Title: Monitoring Neptune's atmosphere with a combination of small
and large telescopes: The role of Spanish Telescopes in a global
    international campaign
Authors: Hueso, R.; Sánchez-Lavega, A.; Roman, M.; Dhillon, V.; de
   Pater, I.; Fletcher, L.; Orton, G. S.; Simon, A.; Wong, M.; Chavez,
   E.; Sromovsky, L.; Fry, P.; Delcroix, M.; Hernández-Bernal, J.;
   Iñurrigarro, P.; Littlefair, S.; Marsh, T.; Ordonez-Etxeberria, I.;
   Pérez-Hoyos, S.; Redwing, E.; Rojas, J. F.; Tollefson, J.
2020sea..confE.102H    Altcode:
  Neptune's atmosphere is covered by tropospheric clouds and hazes that
  evolve in timescales of days, months and years. Given the small apparent
  size of Neptune's disk (2.4"), there are outstanding difficulties in
  obtaining sufficient high-resolution data to trace Neptune's atmospheric
  dynamics and study its variability. Here we present results of an
  international campaign to observe Neptune and we focus in the potential
  of Spanish Telescopes to advance in the knowledge of its atmosphere.

---------------------------------------------------------
Title: Jupiter in the Ultraviolet: Acetylene and Ethane Abundances
    in the Stratosphere of Jupiter from Cassini Observations between
    0.15 and 0.19 μm
Authors: Melin, Henrik; Fletcher, L. N.; Irwin, P. G. J.; Edgington,
   S. G.
2020AJ....159..291M    Altcode: 2020arXiv200509895M
  At wavelengths between 0.15 and 0.19 μm, the far-ultraviolet spectrum
  of Jupiter is dominated by the scattered solar spectrum, attenuated
  by molecular absorptions primarily by acetylene and ethane, and to a
  lesser extent ammonia and phosphine. We describe the development of
  our radiative transfer code that enables the retrieval of abundances
  of these molecular species from ultraviolet reflectance spectra. As a
  proof-of-concept we present an analysis of Cassini Ultraviolet Imaging
  Spectrograph (UVIS) observations of the disk of Jupiter during the
  2000/2001 flyby. The ultraviolet-retrieved acetylene abundances in
  the upper stratosphere are lower than those predicted by models based
  solely on infrared thermal emission from the mid-stratosphere observed
  by the Composite Infrared Spectrometer (CIRS), requiring an adjustment
  to the vertical profiles above 1 mbar. We produce a vertical acetylene
  abundance profile that is compatible with both CIRS and UVIS, with
  reduced abundances at pressures &lt;1 mbar: the 0.1 mbar abundances are
  1.21 ± 0.07 ppm for acetylene and 20.8 ± 5.1 ppm for ethane. Finally,
  we perform a sensitivity study for the JUICE ultraviolet spectrograph,
  which has extended wavelength coverage out to 0.21 μm, enabling the
  retrieval of ammonia and phosphine abundances, in addition to acetylene
  and ethane.

---------------------------------------------------------
Title: Deep learning for the Sun
Authors: Armstrong, John A.; Osborne, Christopher M. J.; Fletcher,
   Lyndsay
2020A&G....61c3.34A    Altcode:
  John A Armstrong, Christopher M J Osborne and Lyndsay Fletcher examine
  how neural networks can be used to explore the nature and location of
  solar activity.

---------------------------------------------------------
Title: Demonstration of X-ray Thomson scattering as diagnostics for
    miscibility in warm dense matter
Authors: Frydrych, S.; Vorberger, J.; Hartley, N. J.; Schuster,
   A. K.; Ramakrishna, K.; Saunders, A. M.; van Driel, T.; Falcone,
   R. W.; Fletcher, L. B.; Galtier, E.; Gamboa, E. J.; Glenzer, S. H.;
   Granados, E.; MacDonald, M. J.; MacKinnon, A. J.; McBride, E. E.;
   Nam, I.; Neumayer, P.; Pak, A.; Voigt, K.; Roth, M.; Sun, P.; Gericke,
   D. O.; Döppner, T.; Kraus, D.
2020NatCo..11.2620F    Altcode:
  The gas and ice giants in our solar system can be seen as a
  natural laboratory for the physics of highly compressed matter at
  temperatures up to thousands of kelvins. In turn, our understanding
  of their structure and evolution depends critically on our ability to
  model such matter. One key aspect is the miscibility of the elements
  in their interiors. Here, we demonstrate the feasibility of X-ray
  Thomson scattering to quantify the degree of species separation in a
  1:1 carbon-hydrogen mixture at a pressure of ~150 GPa and a temperature
  of ~5000 K. Our measurements provide absolute values of the structure
  factor that encodes the microscopic arrangement of the particles. From
  these data, we find a lower limit of 2 4<SUB>-7</SUB><SUP>+6</SUP>?% of
  the carbon atoms forming isolated carbon clusters. In principle, this
  procedure can be employed for investigating the miscibility behaviour
  of any binary mixture at the high-pressure environment of planetary
  interiors, in particular, for non-crystalline samples where it is
  difficult to obtain conclusive results from X-ray diffraction. Moreover,
  this method will enable unprecedented measurements of mixing/demixing
  kinetics in dense plasma environments, e.g., induced by chemistry or
  hydrodynamic instabilities.

---------------------------------------------------------
Title: John Campbell Brown OBE (1947-2019)
Authors: Fletcher, Lyndsay; Labrosse, Nicolas; Mackinnon, Alexander
2020A&G....61b2.14F    Altcode:
  Astronomer Royal for Scotland and inspirational solar physicist,
  by Lyndsay Fletcher, Nicolas Labrosse and Alec MacKinnon.

---------------------------------------------------------
Title: On the Spatial Distribution of Minor Species in Jupiter's
    Troposphere as Inferred From Juno JIRAM Data
Authors: Grassi, D.; Adriani, A.; Mura, A.; Atreya, S. K.; Fletcher,
   L. N.; Lunine, J. I.; Orton, G. S.; Bolton, S.; Plainaki, C.; Sindoni,
   G.; Altieri, F.; Cicchetti, A.; Dinelli, B. M.; Filacchione, G.;
   Migliorini, A.; Moriconi, M. L.; Noschese, R.; Olivieri, A.; Piccioni,
   G.; Sordini, R.; Stefani, S.; Tosi, F.; Turrini, D.
2020JGRE..12506206G    Altcode:
  The spatial distribution of water, ammonia, phosphine, germane, and
  arsine in the Jupiter's troposphere has been inferred from the Jovian
  Infrared Auroral Mapper (JIRAM) Juno data. Measurements allow us to
  retrieve the vertically averaged concentration of gases between ~3
  and 5 bars from infrared-bright spectra. Results were used to create
  latitudinal profiles. The water vapor relative humidity varies with
  latitude from &lt;1% to over 15%. At intermediate latitudes (30-70°)
  the water vapor maxima are associated with the location of cyclonic
  belts, as inferred from mean zonal wind profiles (Porco et al.,
  2003). The high-latitude regions (beyond 60°) are drier in the north
  (mean relative humidity around 2-3%) than the south, where humidity
  reaches 15% around the pole. The ammonia volume mixing ratio varies from
  1 × 10<SUP>-4</SUP> to 4 × 10<SUP>-4</SUP>. A marked minimum exists
  around 10°N, while data suggest an increase over the equator. The
  high-latitude regions are different in the two hemispheres, with a
  gradual increase in the south and more constant values with latitude
  in the north. The phosphine volume mixing ratio varies from 4 ×
  10<SUP>-7</SUP> to 10 × 10<SUP>-7</SUP>. A marked minimum exists in
  the North Equatorial Belt. For latitudes poleward 30°S and 30°N,
  the northern hemisphere appears richer in phosphine, with a decrease
  toward the pole, while the opposite is observed in the south. JIRAM
  data indicate an increase of germane volume mixing ratio from 2 ×
  10<SUP>-10</SUP> to 8 × 10<SUP>-10</SUP> from both poles to 15°S,
  with a depletion centered around the equator. Arsine presents the
  opposite trend, with maximum values of 6 × 10<SUP>-10</SUP> at the
  two poles and minima below 1 × 10<SUP>-10</SUP> around 20°S.

---------------------------------------------------------
Title: Compositional Mapping of Europa with VLT/SPHERE
Authors: King, O. R. T.; Fletcher, L. N.; Ligier, N.
2020LPI....51.2046K    Altcode:
  A high spatial resolution ground-based IR observation of Europa has
  been fit using a Monte Carlo model to calculate compositional abundances
  and uncertainties.

---------------------------------------------------------
Title: New Frontiers-Class Uranus Orbiter: A Case for Exploring the
    Feasibility of Achieving Multidisciplinary Science with a Mid-Scale
    Mission
Authors: Cohen, I. J.; Beddingfield, C. B.; Chancia, R. O.; DiBraccio,
   G. A.; Hedman, M. M.; MacKenzie, S. M.; Mauk, B. H.; Sayanagi,
   K. M.; Soderlund, K. M.; Turtle, E. P.; Adams, E. Y.; Ahrens, C. J.;
   Arridge, C. S.; Brooks, S. M.; Bunce, E. J.; Charnoz, S.; Clark,
   G. B.; Coustenis, A.; Dillman, R. A.; Dutta, S.; Fletcher, L. N.;
   Harbison, R. A.; Helled, R.; Holme, R.; Jozwiak, L. M.; Kasaba, Y.;
   Kollmann, P.; Luszcz-Cook, S.; Mousis, O.; Mura, A.; Murakami, G.;
   Parisi, M.; Rymer, A. M.; Stanley, S.; Stephan, K.; Vervack, R. J.;
   Wong, M. H.; Wurz, P.
2020LPI....51.1428C    Altcode:
  Icy Uranus / Can your system be explored / For New Frontiers cost?

---------------------------------------------------------
Title: Reappraisal and New Constraints on Europa's Surface Composition
    with the Near-Infrared Imaging Spectrometer SINFONI of the VLT
Authors: Ligier, N.; Carter, J.; Poulet, F.; Fletcher, L.; King, O.;
   Brunetto, R.; Massé, M.; Snodgrass, C.
2020LPI....51.1964L    Altcode:
  We present the physico-chemical properties of Europa's surface
  derived from two complementary datasets acquired with the ground-based
  instrument SINFONI (ESO/VLT).

---------------------------------------------------------
Title: CHARISMA: A Space Telescope for Planetary Science
Authors: Young, C. L.; Sayanagi, K. M.; Wong, M. H.; Curry, S.;
   Jessup, K. L.; Becker, T.; Hendrix, A.; Chanover, N.; Milam, S.;
   Holler, B.; Holsclaw, G.; Peralta, J.; Clarke, J.; Spencer, J.;
   Kelley, M.; Luhmann, J.; MacDonnell, D.; Vervack, R.; Rutherford, K.;
   Fletcher, L.; de Pater, I.; Vilas, F.; Simon, A.; Siegmund, O.; Bell,
   J.; Delory, G.; Pitman, J.; Greathouse, T.; Wishnow, E.; Schneider,
   N.; Lillis, R.; Colwell, J.; Bowman, L.; Feaga, L.
2020LPICo2194.6012Y    Altcode:
  No abstract at ADS

---------------------------------------------------------
Title: Measurement of diamond nucleation rates from hydrocarbons at
    conditions comparable to the interiors of icy giant planets
Authors: Schuster, A. K.; Hartley, N. J.; Vorberger, J.; Döppner,
   T.; van Driel, T.; Falcone, R. W.; Fletcher, L. B.; Frydrych, S.;
   Galtier, E.; Gamboa, E. J.; Gericke, D. O.; Glenzer, S. H.; Granados,
   E.; MacDonald, M. J.; MacKinnon, A. J.; McBride, E. E.; Nam, I.;
   Neumayer, P.; Pak, A.; Prencipe, I.; Voigt, K.; Saunders, A. M.; Sun,
   P.; Kraus, D.
2020PhRvB.101e4301S    Altcode:
  We present measurements of the nucleation rate into a diamond lattice
  in dynamically compressed polystyrene obtained in a pump-probe
  experiment using a high-energy laser system and in situ femtosecond
  x-ray diffraction. Different temperature-pressure conditions that
  occur in planetary interiors were probed. For a single shock reaching
  70 GPa and 3000 K no diamond formation was observed, while with a
  double shock driving polystyrene to pressures around 150 GPa and
  temperatures around 5000 K nucleation rates between 10<SUP>29</SUP>
  and 10<SUP>34</SUP>m<SUP>-3</SUP> s<SUP>-1</SUP> were recorded. These
  nucleation rates do not agree with predictions of the state-of-the-art
  theoretical models for carbon-hydrogen mixtures by many orders of
  magnitude. Our data suggest that there is significant diamond formation
  to be expected inside icy giant planets like Neptune and Uranus.

---------------------------------------------------------
Title: A Review of the in Situ Probe Designs from Recent Ice Giant
    Mission Concept Studies
Authors: Simon, A. A.; Fletcher, L. N.; Arridge, C.; Atkinson, D.;
   Coustenis, A.; Ferri, F.; Hofstadter, M.; Masters, A.; Mousis, O.;
   Reh, K.; Turrini, D.; Witasse, O.
2020SSRv..216...17S    Altcode:
  For the Ice Giants, atmospheric entry probes provide critical
  measurements not attainable via remote observations. Including the
  2013-2022 NASA Planetary Decadal Survey, there have been at least five
  comprehensive atmospheric probe engineering design studies performed in
  recent years by NASA and ESA. International science definition teams
  have assessed the science requirements, and each recommended similar
  measurements and payloads to meet science goals with current instrument
  technology. The probe system concept has matured and converged on
  general design parameters that indicate the probe would include a
  1-meter class aeroshell and have a mass around 350 to 400-kg. Probe
  battery sizes vary, depending on the duration of a post-release coast
  phase, and assumptions about heaters and instrument power needs. The
  various mission concepts demonstrate the need for advanced power and
  thermal protection system development. The many completed studies show
  an Ice Giant mission with an in situ probe is feasible and would be
  welcomed by the international science community.

---------------------------------------------------------
Title: Saturn atmospheric dynamics one year after Cassini: Long-lived
    features and time variations in the drift of the Hexagon
Authors: Hueso, R.; Sánchez-Lavega, A.; Rojas, J. F.; Simon, A. A.;
   Barry, T.; Río-Gaztelurrutia, T. del; Antuñano, A.; Sayanagi, K. M.;
   Delcroix, M.; Fletcher, L. N.; García-Melendo, E.; Pérez-Hoyos, S.;
   Blalock, J.; Colas, F.; Gómez-Forrellad, J. M.; Gunnarson, J. L.;
   Peach, D.; Wong, M. H.
2020Icar..33613429H    Altcode: 2019arXiv190913849H
  We examine Saturn's atmospheric dynamics with observations in the
  visible range from ground-based telescopes and Hubble Space Telescope
  (HST). We present a detailed analysis of observations acquired
  during 2018 obtaining drift rates of major meteorological systems
  from the equator to the north polar hexagon. A system of polar storms
  that appeared in the planet in March 2018 and remained active with a
  complex phenomenology at least until September is analyzed elsewhere
  (Sánchez-Lavega et al., 2019). Many of the regular cloud features
  visible in 2018 are long-lived and can be identified in Saturn
  images in 2017, and in some cases, for up to a decade using also
  Cassini ISS images. Without considering the polar storms, the most
  interesting long-lived cloud systems are: <P />i) A bright white spot
  in the Equatorial Zone that can be tracked continuously since 2014
  with minimal changes in its zonal velocity, which was 444.3 ± 3.1 m
  s<SUP>-1</SUP> in 2014 and 452.4 ± 1.7 m s<SUP>-1</SUP> in 2018. This
  velocity is remarkably different from the zonal winds at the cloud level
  at its latitude during the Cassini mission, and is closer to zonal
  winds obtained at the time of the Voyagers flybys and to zonal winds
  from Cassini VIMS infrared images of the lower atmosphere. <P />ii)
  A large long-lived Anticyclone Vortex, here AV, that formed after the
  Great White Spot of 2010-2011. This vortex has changed significantly in
  visual contrast, drift rate and latitude with minor changes in size over
  the last years. <P />iii) A system of subpolar vortices at latitudes
  60-65°N present at least since 2011. These vortices and additional
  atmospheric features here studied follow drift rates consistent with
  zonal winds obtained by Cassini. <P />We also present a study of the
  positions of the vertices of Saturn's north polar hexagon from 2015 to
  2018. These measurements are compared with previous analyses during
  the Cassini mission (2007-2014), observations with HST in the 90s,
  and data from the Voyagers in 1980-1981 to explore the long-term
  variability of the hexagon's drift rate. We find variations in the
  drift rate of the hexagon through these epochs that can not be fit
  by seasonal changes in the polar area. Instead, the different drift
  rates reinforce the role of the North Polar Spot that was present in
  the Voyager epoch and in the early 90s to cause a faster drift rate
  of the hexagon at that time compared with the current slower one.

---------------------------------------------------------
Title: Origins Space Telescope (Origins): Solar System Science
Authors: Ennico-Smith, K.; Milam, S.; Bauer, J.; Cordiner, M.; de
   Pater, I.; Fletcher, L.; Lis, D.; Lovell, A.; Moullet, A.; Orton,
   G.; Villanueva, G.; Origins Solar System Working Group
2020AAS...23517108E    Altcode:
  The Origins Space Telescope (Origins) is a 2020 Decadal mission
  concept that will trace our cosmic history, from the formation of the
  first galaxies and the rise of metals and dust to the development of
  habitable worlds and present-day life. With more than three orders of
  magnitude improvement in sensitivity over prior far-infrared missions
  and access to a spectral range spanning nearly eight octaves (2.8-588
  microns), Origins vastly expands the discovery space available to the
  community. Origins is also an agile observatory, capable of tracking
  moving objects &gt; 60 mas/s, and executing rapid survey science. This
  presentation describes a sampling of Solar System science cases to
  illustrate the capabilities of this breakthrough mission. For example,
  Origins can advance our knowledge of the thermal history and present-day
  climate and circulation patterns of the Giant Planets, providing a
  ground-truth catalog of giant planet variability as a resource to the
  exoplanet community. Origins can deliver a survey of the sizes and
  thermal properties of small bodies in the outer Solar System, allowing
  us to probe the history and evolution of our Solar System. No survey has
  been done on this scale before. Origins can trace the origin of water on
  Earth and in our Solar System by determining the D/H ratio in hundreds
  of comets, providing, for the first time, a statistically-significant
  sample of this critical fingerprint for the origin of water
  on Earth. We thank NASA HQ, GSFC, JPL, and NASA-Ames for their
  support of the study. To learn more about Origins see our websites (<A
  href="https://origins.ipac.caltech.edu">https://origins.ipac.caltech.edu</A>
  and <A
  href="https://asd.gsfc.nasa.gov/firs/">https://asd.gsfc.nasa.gov/firs/</A>)
  and report (<A
  href="https://asd.gsfc.nasa.gov/firs/docs/OriginsVolume1MissionConceptStudyReport.pdf">https://asd.gsfc.nasa.gov/firs/docs/OriginsVolume1MissionConceptStudyReport.pdf</A>).

---------------------------------------------------------
Title: A Multi-Spectral Analysis of Recent Perturbations to Jupiter's
    Great Red Spot in 2019
Authors: Orton, G. S.; Momary, T.; Sinclair, J. A.; Fujiyoshi, T.;
   Honda, M.; Rogers, J.; Foster, C.; Eichstädt, G.; Antuñano, A.;
   Fletcher, L. N.; Chowdhury, N.; Stallard, T.; Melin, H.
2019AGUFM.P21G3445O    Altcode:
  In the early months of 2019, various amateur planetary observers
  recorded interactions between the Great Red Spot (GRS) and a series of
  ring-like vortices that were transported toward its northeastern side
  along the southern boundary of the South Equatorial Belt. Ultimately
  these were drawn into the Great Red Spot Hollow, a bright region
  surrounding the uniquely red-colored GRS itself. This resulted in their
  deformation and dissolution, as well as the formation of red-colored
  regions that became known as "flakes" within the Hollow on the western
  side of the GRS that appear to be as bright in "methane-band" (~890-nm)
  images as the interior of the GRS itself. We will report on the results
  of strategic imaging results on May, 27-28, 2019, from 2.3 to 24.5 µ
  m from the Subaru Telescope and the Infrared Telescope Facility that
  show surprising perturbations to the atmosphere and their aftermath.

---------------------------------------------------------
Title: Saturn's Rings: Atmsopheric Effects of Ring Shadow, Ring Shine,
    and Thermal Emission
Authors: Edgington, S. G.; Atreya, S. K.; West, R. A.; Baines, K.;
   Fletcher, L. N.
2019AGUFM.P13B3511E    Altcode:
  Cassini explored for nearly a half Saturnian year. During this epoch,
  in addition to seasonal solar inclination changes, the ring shadow moved
  from the northern hemisphere to covering a large region of the southern
  hemisphere. The intensity of both ultraviolet and visible sunlight
  penetrating through the rings varied depending on Saturn's axial tilt
  relative to the Sun and the optical thickness of each ring system,
  i.e. the rings act like semi-transparent venetian blinds. This effect
  magnifies the seasonal effect of axial tilt alone acting to reduce or
  even turn off photochemistry and haze generation, an effect exhibited by
  the presence of a bluish northern atmosphere in 2004 and color change to
  blue in the southern hemisphere after equinox. We report on the impact
  of the oscillating ring shadow, seasonal axial tilt, and solar cycle,
  on photochemistry of hydrocarbons, ammonia, and phosphine in Saturn's
  stratosphere and upper troposphere. The impact on the abundance of
  long-lived photochemical products leading to haze formation and on
  disequilibrium species is explored. Data from Cassini's CIRS, UVIS,
  and VIMS datasets that provide constraints for hazes and molecular
  abundances. <P />In addition to visible light reflected from the
  rings, UV photons have also been shown to reflect from the rings. This
  acts to enhance photolysis on the sunlit hemisphere. We examine the
  impact of ultraviolet ring-shine on the photochemistry of the upper
  atmosphere. Lastly, we examine the impact of thermal ring photons on
  the heating of the hemisphere upon which they shine. <P />The research
  described in this paper was carried out in part at the Jet Propulsion
  Laboratory, California Institute of Technology, under a contract
  with the National Aeronautics and Space Administration. Copyright
  2019 California Institute of Technology. Government sponsorship is
  acknowledged.

---------------------------------------------------------
Title: Longitudinal Variations in the Stratosphere of Uranus from
    the Spitzer Infrared Spectrometer
Authors: Rowe-Gurney, N.; Fletcher, L. N.; Orton, G. S.; Roman, M. T.;
   Mainzer, A.; Moses, J. I.; De Pater, I.; Irwin, P. G.
2019AGUFM.P13B3504R    Altcode:
  NASA's Spitzer Infrared Spectrometer (IRS) acquired mid-infrared
  (5-37 μm) disc-averaged spectra of Uranus very near its equinox
  over 21.7 hours on 16<SUP>th</SUP> to 17<SUP>th</SUP> of December
  2007. A global-mean spectrum was constructed from observations
  of multiple longitudes, spaced equally around the planet, and have
  provided the opportunity for the most comprehensive globally-averaged
  characterisation of Uranus' temperature and composition ever obtained
  (Orton et al., 2014a,b). In this work, we analyse the disc-averaged
  spectra at four separate longitudes to shed light on the discovery
  of longitudinal variability occurring in Uranus' stratosphere
  during the 2007 equinox. We detect a variability of up to 15% at
  stratospheric altitudes sensitive to methane, ethane, and acetylene
  (∼ 0.1 mbar). The tropospheric hydrogen-helium continuum exhibits a
  negligible variation of less than 2%, constraining the phenomenon to
  the stratosphere. Observations from Keck II NIRCII in December 2007
  (Sromovsky et al., 2009; de Pater et al., 2011) and VLT/VISIR in 2009
  (Roman et al. in-prep) suggest possible links to these variations in
  the form of discrete meteorological features. It now seems clear that
  the variations are located in the bright polar cap of emission seen
  in the VLT observations. These variations were most obvious at the
  boundary between the equator and the polar cap (i.e., somewhere at mid
  latitudes). Building on the forward-modelling analysis of the global
  average study, we present full optimal estimation inversions (using the
  NEMESIS retrieval algorithm, Irwin et al., 2008) of the spectra at each
  longitude to distinguish between thermal and compositional variability.

---------------------------------------------------------
Title: IRTF-TEXES observations of stratospheric CH<SUB>3</SUB>
    and CH<SUB>4</SUB> emission at Jupiter's high latitudes
Authors: Sinclair, J. A.; Greathouse, T. K.; Giles, R.; Antuñano,
   A.; Fouchet, T.; Bezard, B.; Clark, G. B.; Moses, J. I.; Hue, V.;
   Orton, G. S.; Fletcher, L. N.; Irwin, P. G.
2019AGUFM.P21G3444S    Altcode:
  The neutral atmosphere, external magnetosphere and solar-wind
  environment of Jupiter are coupled within Jupiter's auroral
  regions. Energetic particles deposit their energy as deep as the
  1-mbar level (or ~150 km above the 1-bar level) and modify the
  thermal structure and chemistry of the atmosphere (Sinclair et
  al., 2017, Icarus 292, 182-207, Sinclair et al., 2018, Icarus 300,
  305-326). Clark et al., 2018 (JGR Space Physics 123, 7554-7567)
  recently performed a comparative analysis of Juno-JEDI (Jovian Electron
  Distribution Experiment, Mauk et al., 2017, SSR 213(1-4), 289-346)
  and HISAKI-EXCEED (Extreme Ultraviolet Spectroscope for Exospheric
  Dynamics, Yoshioka et al., 2013, P&amp;SS 85, 250-260) ultraviolet
  observations of Jupiter's aurora. They found that the agreement
  between both datasets was optimized when CH<SUB>4</SUB> and other
  hydrocarbons were allowed to be transported to higher altitudes in their
  atmospheric model. This suggests that a phenomenon within Jupiter's
  auroral regions is acting to increase the eddy diffusion coefficient
  and the height of the hydrocarbon homopause. In order to test this
  hypothesis, we present a retrieval analysis of IRTF-TEXES spectra of
  CH<SUB>3</SUB> (methyl radical) and CH<SUB>4</SUB> emission of Jupiter's
  high latitudes. Spectra were measured on February 12<SUP>th</SUP>
  (coincident with Juno's 18<SUP>th</SUP> perijove), April 16<SUP>th</SUP>
  and 21<SUP>st</SUP> 2019 (10 and 15 days after Juno's 19<SUP>th</SUP>
  perijove, respectively). A retrieval analysis was performed to derive
  the vertical profiles of temperature and CH<SUB>3</SUB> abundance
  (from 20 mbar to 1 µbar) and their horizontal variation poleward of
  ±45º in latitude. Preliminary retrievals of spectra measured on April
  16<SUP>th</SUP> 2019 demonstrate that the abundance of CH<SUB>3</SUB>
  is enhanced over Jupiter's northern auroral region (60°N - pole,
  150-220°W) compared to non-auroral longitudes in the same latitude
  band. This is suggestive that the production rate of CH<SUB>3</SUB>
  is higher and/or the hydrocarbon homopause altitude is indeed higher
  in Jupiter's auroral regions.

---------------------------------------------------------
Title: Science Requirement Document (SRD) for the European Solar
    Telescope (EST) (2nd edition, December 2019)
Authors: Schlichenmaier, R.; Bellot Rubio, L. R.; Collados, M.;
   Erdelyi, R.; Feller, A.; Fletcher, L.; Jurcak, J.; Khomenko, E.;
   Leenaarts, J.; Matthews, S.; Belluzzi, L.; Carlsson, M.; Dalmasse,
   K.; Danilovic, S.; Gömöry, P.; Kuckein, C.; Manso Sainz, R.;
   Martinez Gonzalez, M.; Mathioudakis, M.; Ortiz, A.; Riethmüller,
   T. L.; Rouppe van der Voort, L.; Simoes, P. J. A.; Trujillo Bueno,
   J.; Utz, D.; Zuccarello, F.
2019arXiv191208650S    Altcode:
  The European Solar Telescope (EST) is a research infrastructure
  for solar physics. It is planned to be an on-axis solar telescope
  with an aperture of 4 m and equipped with an innovative suite of
  spectro-polarimetric and imaging post-focus instrumentation. The EST
  project was initiated and is driven by EAST, the European Association
  for Solar Telescopes. EAST was founded in 2006 as an association
  of 14 European countries. Today, as of December 2019, EAST consists
  of 26 European research institutes from 18 European countries. The
  Preliminary Design Phase of EST was accomplished between 2008 and
  2011. During this phase, in 2010, the first version of the EST Science
  Requirement Document (SRD) was published. After EST became a project
  on the ESFRI roadmap 2016, the preparatory phase started. The goal
  of the preparatory phase is to accomplish a final design for the
  telescope and the legal governance structure of EST. A major milestone
  on this path is to revisit and update the Science Requirement Document
  (SRD). The EST Science Advisory Group (SAG) has been constituted by
  EAST and the Board of the PRE-EST EU project in November 2017 and has
  been charged with the task of providing with a final statement on the
  science requirements for EST. Based on the conceptual design, the SRD
  update takes into account recent technical and scientific developments,
  to ensure that EST provides significant advancement beyond the current
  state-of-the-art. The present update of the EST SRD has been developed
  and discussed during a series of EST SAG meetings. The SRD develops
  the top-level science objectives of EST into individual science
  cases. Identifying critical science requirements is one of its main
  goals. Those requirements will define the capabilities of EST and the
  post-focus instrument suite. The technical requirements for the final
  design of EST will be derived from the SRD.

---------------------------------------------------------
Title: Jupiter's Stratosphere in the Ultraviolet: inter-annual
    variability of acetylene and ethane
Authors: Melin, H.; Fletcher, L. N.
2019AGUFM.P13B3503M    Altcode:
  The ultraviolet spectrum of Jupiter between 150 and 200 nm is
  dominated by Rayleigh scattered sunlight, augmented by absorption
  from stratospheric acetylene and ethane, and tropospheric ammonia
  and phosphine. Acetylene and ethane are both photochemical products of
  methane, and their meridional distribution traces the global circulation
  in the stratosphere. However, they are observed to have very different
  distributions on the planet, attributable to their very different
  chemical lifetimes - ethane can persist for several Jupiter years,
  tracing the stratospheric circulation. Ammonia and phosphine are both
  tracers of vertical motions in the atmosphere, lifting these species up
  into the upper troposphere where they can be observed. Jupiter's Quasi
  Quadrennial Oscillation (QQO) is a four-year semi-regular temperature
  variation in the equatorial stratosphere of Jupiter, likely driven by
  gravity waves generated by the turbulent troposphere. Here, we analyse
  observations from the International Ultraviolet Explorer (IUE) space
  telescope and the Astro-1 &amp; 2 Space Shuttle missions that carried
  the Hopkins Ultraviolet Telescope (HUT), obtained between 1978 and
  1996, at a greater than yearly cadence, covering 1.5 jovian years. We
  examine how sensitive these observations are to the abundance of ethane,
  acetylene, ammonia and phosphine. Using the NEMESIS radiative transfer
  and retrieval code, we examine how the vertical profiles of acetylene
  and ethane evolve on jovian inter-annual, annual, seasonal, and QQO
  time-scales. We also explore retrievability of ammonia and phosphine
  abundance to examine how the vertical mixing changes over this period.

---------------------------------------------------------
Title: Rapid time variability of the UV spectral line profiles in
    a small flare - evidence of chromospheric turbulence and heating
Authors: Fletcher, L.; Jeffrey, N. L. S.; Labrosse, N.; Simoes,
   P. J. D. A.
2019AGUFMSH13D3424F    Altcode:
  We present observations of rapid variations in the spectral line
  profiles in the B-class flare SOL2016-12-06T10:36:58 detected by the
  Interface Region Imaging Spectograph (IRIS). The flare was observed at a
  cadence of 1.7s, a time resolution that allows us to detect variations
  during the flare rise and its rapid subsequent evolution, as follows:
  (i) For Si IV 1402.77Å, the line broadens significantly above its
  expected thermal width around 10 seconds prior to the flare's strong
  radiative signatures. Modelling shows that in this event the Si IV
  line is optically thin, so the evolving line broadening suggests
  the development of transition region turbulence, leading to flare
  heating; (ii) In the optically thick Mg II k line, formed deeper in
  the chromosphere, marked differences appear in the time profiles of
  the core and wing intensities, and there are also rapidly varying line
  asymmetries and a filling in of the pre-flare central reversal of this
  line. An increase in the line core width is also seen. We will discuss
  possible interpretations of the evolution these two lines in the context
  of evolving turbulence and chromospheric pressure, and opacity effects.

---------------------------------------------------------
Title: Herschel map of Saturn's stratospheric water, delivered by
    the plumes of Enceladus
Authors: Cavalié, T.; Hue, V.; Hartogh, P.; Moreno, R.; Lellouch,
   E.; Feuchtgruber, H.; Jarchow, C.; Cassidy, T.; Fletcher, L. N.;
   Billebaud, F.; Dobrijevic, M.; Rezac, L.; Orton, G. S.; Rengel, M.;
   Fouchet, T.; Guerlet, S.
2019A&A...630A..87C    Altcode: 2019arXiv190807399C
  Context. The origin of water in the stratospheres of giant planets
  has been an outstanding question ever since its first detection by
  the Infrared Space Observatory some 20 years ago. Water can originate
  from interplanetary dust particles, icy rings and satellites, and large
  comet impacts. Analyses of Herschel Space Observatory observations have
  proven that the bulk of Jupiter's stratospheric water was delivered
  by the Shoemaker-Levy 9 impacts in 1994. In 2006, the Cassini mission
  detected water plumes at the South Pole of Enceladus, which made the
  moon a serious candidate for Saturn's stratospheric water. Further
  evidence was found in 2011 when Herschel demonstrated the presence
  of a water torus at the orbital distance of Enceladus that was fed by
  the moon's plumes. Finally, water falling from the rings onto Saturn's
  uppermost atmospheric layers at low latitudes was detected during the
  final orbits of Cassini's end-of-mission plunge into the atmosphere. <BR
  /> Aims: In this paper, we use Herschel mapping observations of water
  in Saturn's stratosphere to identify its source. <BR /> Methods: We
  tested several empirical models against the Herschel-HIFI and -PACS
  observations, which were collected on December 30, 2010, and January
  2, 2011, respectively. <BR /> Results: We demonstrate that Saturn's
  stratospheric water is not uniformly mixed as a function of latitude,
  but peaks at the equator and decreases poleward with a Gaussian
  distribution. We obtain our best fit with an equatorial mole fraction
  1.1 ppb and a half width at half maximum of 25°, when accounting
  for a temperature increase in the two warm stratospheric vortices
  produced by Saturn's Great Storm of 2010-2011. <BR /> Conclusions:
  This work demonstrates that Enceladus is the main source of Saturn's
  stratospheric water. <P />Herschel is an ESA space observatory with
  science instruments provided by European-led Principal Investigator
  consortia and with important participation from NASA.

---------------------------------------------------------
Title: Achievements of Hinode in the first eleven years
Authors: Hinode Review Team; Al-Janabi, Khalid; Antolin, Patrick;
   Baker, Deborah; Bellot Rubio, Luis R.; Bradley, Louisa; Brooks,
   David H.; Centeno, Rebecca; Culhane, J. Leonard; Del Zanna, Giulio;
   Doschek, George A.; Fletcher, Lyndsay; Hara, Hirohisa; Harra,
   Louise K.; Hillier, Andrew S.; Imada, Shinsuke; Klimchuk, James A.;
   Mariska, John T.; Pereira, Tiago M. D.; Reeves, Katharine K.; Sakao,
   Taro; Sakurai, Takashi; Shimizu, Toshifumi; Shimojo, Masumi; Shiota,
   Daikou; Solanki, Sami K.; Sterling, Alphonse C.; Su, Yingna; Suematsu,
   Yoshinori; Tarbell, Theodore D.; Tiwari, Sanjiv K.; Toriumi, Shin;
   Ugarte-Urra, Ignacio; Warren, Harry P.; Watanabe, Tetsuya; Young,
   Peter R.
2019PASJ...71R...1H    Altcode:
  Hinode is Japan's third solar mission following Hinotori (1981-1982)
  and Yohkoh (1991-2001): it was launched on 2006 September 22 and is in
  operation currently. Hinode carries three instruments: the Solar Optical
  Telescope, the X-Ray Telescope, and the EUV Imaging Spectrometer. These
  instruments were built under international collaboration with the
  National Aeronautics and Space Administration and the UK Science and
  Technology Facilities Council, and its operation has been contributed
  to by the European Space Agency and the Norwegian Space Center. After
  describing the satellite operations and giving a performance evaluation
  of the three instruments, reviews are presented on major scientific
  discoveries by Hinode in the first eleven years (one solar cycle long)
  of its operation. This review article concludes with future prospects
  for solar physics research based on the achievements of Hinode.

---------------------------------------------------------
Title: Jupiter's auroral-related stratospheric heating and
chemistry III: Abundances of C<SUB>2</SUB>H<SUB>4</SUB>,
    CH<SUB>3</SUB>C<SUB>2</SUB>H, C<SUB>4</SUB>H<SUB>2</SUB> and
    C<SUB>6</SUB>H<SUB>6</SUB> from Voyager-IRIS and Cassini-CIRS
Authors: Sinclair, J. A.; Moses, J. I.; Hue, V.; Greathouse, T. K.;
   Orton, G. S.; Fletcher, L. N.; Irwin, P. G. J.
2019Icar..328..176S    Altcode:
  We present an analysis of Voyager-1-IRIS and Cassini-CIRS
  spectra of Jupiter's high latitudes acquired during the
  spacecrafts' respective flybys in November 1979 and January
  2001. We performed a forward-model analysis in order to derive the
  abundances of ethylene (C<SUB>2</SUB>H<SUB>4</SUB>), methylacetylene
  (CH<SUB>3</SUB>C<SUB>2</SUB>H), diacetylene (C<SUB>4</SUB>H<SUB>2</SUB>)
  and benzene (C<SUB>6</SUB>H<SUB>6</SUB>) in Jupiter's northern and
  southern auroral regions. We also compared these abundances to:
  1) lower-latitude abundances predicted by the Moses et al. (2005)
  'Model A' photochemical model, henceforth 'Moses 2005A', and
  2) abundances derived at non-auroral longitudes in the same
  latitude band. This paper serves as an extension of Sinclair et
  al. (2017b), where we retrieved the vertical profiles of temperature,
  C<SUB>2</SUB>H<SUB>2</SUB> and C<SUB>2</SUB>H<SUB>6</SUB> from similar
  datasets. We find that an enrichment of C<SUB>2</SUB>H<SUB>4</SUB>,
  CH<SUB>3</SUB>C<SUB>2</SUB>H and C<SUB>6</SUB>H<SUB>6</SUB> with
  respect to lower-latitude abundances is required to fit the spectra
  of Jupiter's northern and southern auroral regions. For example, for
  CIRS 0.5 cm<SUP>-1</SUP> spectra of Jupiter's southern auroral region,
  scale factor enrichments of 6.40<SUB>-1.15</SUB><SUP>+1.30</SUP>
  and 9.60<SUB>-3.67</SUB><SUP>+3.98</SUP> are required with respect
  to the Moses 2005A vertical profiles of C<SUB>2</SUB>H<SUB>4</SUB>
  and C<SUB>6</SUB>H<SUB>6</SUB>, respectively, in order to fit
  the spectral emission features of these species at ∼950 and
  ∼674 cm<SUP>-1</SUP>. Similarly, in order to fit the CIRS 2.5
  cm<SUP>-1</SUP> spectra of Jupiter's northern auroral region, scale
  factor enrichments of 1.60<SUB>-0.21</SUB><SUP>+0.37</SUP>,
  3.40<SUB>-1.69</SUB><SUP>+1.89</SUP> and
  15.00<SUB>-4.02</SUB><SUP>+4.01</SUP> with respect to the
  Moses 2005A vertical profiles of C<SUB>2</SUB>H<SUB>4</SUB>,
  CH<SUB>3</SUB>C<SUB>2</SUB>H and C<SUB>6</SUB>H<SUB>6</SUB>
  were required, respectively. Outside of Jupiter's auroral
  region in the same latitude bands, only upper-limit abundances
  of C<SUB>2</SUB>H<SUB>4</SUB>, CH<SUB>3</SUB>C<SUB>2</SUB>H and
  C<SUB>6</SUB>H<SUB>6</SUB> could be determined due to the limited
  sensitivity of the measurements, the weaker emission features combined
  with cooler stratospheric temperatures (and therefore decreased
  thermal emission) of these regions. Nevertheless, for a subset of the
  observations, derived abundances of C<SUB>2</SUB>H<SUB>4</SUB> and
  C<SUB>6</SUB>H<SUB>6</SUB> in Jupiter's auroral regions were higher
  (by 1 σ) with respect to upper-limit abundances derived outside
  the auroral region in the same latitude band. This is suggestive
  that the influx of energetic ions and electrons from the Jovian
  magnetosphere and external solar-wind environment into the neutral
  atmosphere in Jupiter's auroral regions drives enhanced ion-related
  chemistry, as has also been inferred from Cassini observations of
  Saturn's high latitudes (Fletcher et al., 2018; Guerlet et al., 2015;
  Koskinen et al., 2016). We were not able to constrain the abundance
  of C<SUB>4</SUB>H<SUB>2</SUB> in either Jupiter's auroral regions or
  non-auroral regions due to its lower (predicted) abundance and weaker
  emission feature. Thus, only upper-limit abundances were derived in
  both locations. From CIRS 2.5 cm<SUP>-1</SUP> spectra, the upper limit
  abundance of C<SUB>4</SUB>H<SUB>2</SUB> corresponds to a scale factor
  enhancement of 45.6 and 23.8 with respect to the Moses 2005A vertical
  profile in Jupiter's non-auroral and auroral regions.

---------------------------------------------------------
Title: The Role of Energy Diffusion in the Deposition of Energetic
    Electron Energy in Solar and Stellar Flares
Authors: Jeffrey, Natasha L. S.; Kontar, Eduard P.; Fletcher, Lyndsay
2019ApJ...880..136J    Altcode: 2019arXiv190601887J
  During solar flares, a large fraction of the released magnetic energy
  is carried by energetic electrons that transfer and deposit energy
  in the Sun’s atmosphere. Electron transport is often approximated
  by a cold thick-target model, assuming that electron energy is much
  larger than the temperature of the ambient plasma, and electron energy
  evolution is modeled as a systematic loss. Using kinetic modeling
  of electrons, we reevaluate the transport and deposition of flare
  energy. Using a full collisional warm-target model (WTM), we account
  for electron thermalization and for the properties of the ambient
  coronal plasma such as its number density, temperature and spatial
  extent. We show that the deposition of nonthermal electron energy in the
  lower atmosphere is highly dependent on the properties of the flaring
  coronal plasma. In general, thermalization and a reduced WTM energy
  loss rate leads to an increase of nonthermal energy transferred to
  the chromosphere, and the deposition of nonthermal energy at greater
  depths. The simulations show that energy is deposited in the lower
  atmosphere initially by high-energy nonthermal electrons, and later by
  lower energy nonthermal electrons that partially or fully thermalize
  in the corona, over timescales of seconds, unaccounted for in previous
  studies. This delayed heating may act as a diagnostic of both the
  injected nonthermal electron distribution and the coronal plasma,
  vital for constraining flare energetics.

---------------------------------------------------------
Title: The plasmoid instability in a confined solar flare
Authors: MacTaggart, David; Fletcher, Lyndsay
2019MNRAS.486L..96M    Altcode: 2019MNRAS.tmpL..70M; 2019arXiv190501201M
  Eruptive flares (EFs) are associated with erupting filaments and, in
  some models, filament eruption drives flare reconnection. Recently,
  however, observations of a confined flare (CF) have revealed all the
  hallmarks of an EF (impulsive phase, flare ribbons, etc.) without the
  filament eruption itself. Therefore, if the filament is not primarily
  responsible for impulsive flare reconnection, what is? In this Letter,
  we argue, based on mimimal requirements, that the plasmoid instability
  is a strong candidate for explaining the impulsive phase in the observed
  CF. We present magnetohydrodynamic simulation results of the non-linear
  development of the plasmoid instability, in a model active region
  magnetic field geometry, to strengthen our claim. We also discuss
  how the ideas described in this Letter can be generalized to other
  situations, including EFs.

---------------------------------------------------------
Title: Fast Solar Image Classification Using Deep Learning and Its
    Importance for Automation in Solar Physics
Authors: Armstrong, John A.; Fletcher, Lyndsay
2019SoPh..294...80A    Altcode: 2019arXiv190513575A
  The volume of data being collected in solar physics has exponentially
  increased over the past decade and with the introduction of the
  Daniel K. Inouye Solar Telescope (DKIST) we will be entering the
  age of petabyte solar data. Automated feature detection will be
  an invaluable tool for post-processing of solar images to create
  catalogues of data ready for researchers to use. We propose a deep
  learning model to accomplish this; a deep convolutional neural network
  is adept at feature extraction and processing images quickly. We train
  our network using data from Hinode/Solar Optical Telescope (SOT) Hα
  images of a small subset of solar features with different geometries:
  filaments, prominences, flare ribbons, sunspots and the quiet Sun
  (i.e. the absence of any of the other four features). We achieve near
  perfect performance on classifying unseen images from SOT (≈ 99.9%)
  in 4.66 seconds. We also for the first time explore transfer learning
  in a solar context. Transfer learning uses pre-trained deep neural
  networks to help train new deep learning models i.e. it teaches a new
  model. We show that our network is robust to changes in resolution
  by degrading images from SOT resolution (≈0.33<SUP>″</SUP> at λ
  =6563 Å) to Solar Dynamics Observatory/Atmospheric Imaging Assembly
  (SDO/AIA) resolution (≈1.2<SUP>″</SUP>) without a change in
  performance of our network. However, we also observe where the network
  fails to generalise to sunspots from SDO/AIA bands 1600/1700 Å due
  to small-scale brightenings around the sunspots and prominences in
  SDO/AIA 304 Å due to coronal emission.

---------------------------------------------------------
Title: Spectral Evidence for Heating at Large Column Mass in Umbral
    Solar Flare Kernels. I. IRIS Near-UV Spectra of the X1 Solar Flare
    of 2014 October 25
Authors: Kowalski, Adam F.; Butler, Elizabeth; Daw, Adrian N.;
   Fletcher, Lyndsay; Allred, Joel C.; De Pontieu, Bart; Kerr, Graham S.;
   Cauzzi, Gianna
2019ApJ...878..135K    Altcode: 2019arXiv190502111K
  The GOES X1 flare SOL2014-10-25T17:08:00 was a three-ribbon solar
  flare observed with the Interface Region Imaging Spectrograph (IRIS)
  in the near-UV (NUV) and far-UV. One of the flare ribbons crossed
  a sunspot umbra, producing a dramatic, ∼1000% increase in the NUV
  continuum radiation. We comprehensively analyze the UV spectral data
  of the umbral flare brightenings, which provide new challenges for
  radiative-hydrodynamic modeling of the chromospheric velocity field and
  the white-light continuum radiation. The emission line profiles in the
  umbral flare brightenings exhibit redshifts and profile asymmetries,
  but these are significantly smaller than in another, well-studied
  X-class solar flare. We present a ratio of the NUV continuum intensity
  to the Fe II λ2814.45 intensity. This continuum-to-line ratio is a
  new spectral diagnostic of significant heating at high column mass
  (log m/[g cm<SUP>-2</SUP>] &gt; -2) during solar flares because the
  continuum and emission line radiation originate from relatively similar
  temperatures but moderately different optical depths. The full spectral
  readout of these IRIS data also allow for a comprehensive survey of the
  flaring NUV landscape: in addition to many lines of Fe II and Cr II, we
  identify a new solar flare emission line, He I λ2829.91 (as previously
  identified in laboratory and early-type stellar spectra). The Fermi/GBM
  hard X-ray data provide inputs to radiative-hydrodynamic models (which
  will be presented in Paper II) in order to better understand the large
  continuum-to-line ratios, the origin of the white-light continuum
  radiation, and the role of electron beam heating in the low atmosphere.

---------------------------------------------------------
Title: A brightening of Jupiter's auroral 7.8-μm CH<SUB>4</SUB>
    emission during a solar-wind compression
Authors: Sinclair, J. A.; Orton, G. S.; Fernandes, J.; Kasaba,
   Y.; Sato, T. M.; Fujiyoshi, T.; Tao, C.; Vogt, M. F.; Grodent, D.;
   Bonfond, B.; Moses, J. I.; Greathouse, T. K.; Dunn, W.; Giles, R. S.;
   Tabataba-Vakili, F.; Fletcher, L. N.; Irwin, P. G. J.
2019NatAs...3..607S    Altcode: 2019NatAs.tmp..243S
  Enhanced mid-infrared emission from CH<SUB>4</SUB> and other
  stratospheric hydrocarbons has been observed coincident with Jupiter's
  ultraviolet auroral emission<SUP>1-3</SUP>. This suggests that auroral
  processes and the neutral stratosphere of Jupiter are coupled; however,
  the exact nature of this coupling is unknown. Here we present a time
  series of Subaru-COMICS images of Jupiter measured at a wavelength
  of 7.80 μm on 11-14 January, 4-5 February and 17-20 May 2017. These
  data show that both the morphology and magnitude of the auroral
  CH<SUB>4</SUB> emission vary on daily timescales in relation to external
  solar-wind conditions. The southern auroral CH<SUB>4</SUB> emission
  increased in brightness temperature by about 3.8 K between 15:50 ut,
  11 January and 12:57 ut, 12 January, during a predicted solar-wind
  compression. During the same compression, the northern auroral
  emission exhibited a duskside brightening, which mimics the morphology
  observed in the ultraviolet auroral emission during periods of enhanced
  solar-wind pressure<SUP>4,5</SUP>. These results suggest that changes
  in external solar-wind conditions perturb the Jovian magnetosphere in
  such a way that energetic particles are accelerated into the planet's
  atmosphere, deposit their energy as deep as the neutral stratosphere,
  and modify the thermal structure, the abundance of CH<SUB>4</SUB> or
  the population of energy states of CH<SUB>4</SUB>. We also find that
  the northern and southern auroral CH<SUB>4</SUB> emission evolved
  independently between the January, February and May images, as has
  been observed at X-ray wavelengths over shorter timescales<SUP>6</SUP>
  and at mid-infrared wavelengths over longer timescales<SUP>7</SUP>.

---------------------------------------------------------
Title: First Spectral Analysis of a Solar Plasma Eruption Using ALMA
Authors: Rodger, Andrew S.; Labrosse, Nicolas; Wedemeyer, Sven;
   Szydlarski, Mikolaj; Simões, Paulo J. A.; Fletcher, Lyndsay
2019ApJ...875..163R    Altcode: 2019arXiv190201319R
  The aim of this study is to demonstrate how the logarithmic
  millimeter continuum gradient observed using the Atacama Large
  Millimeter/submillimeter Array (ALMA) may be used to estimate optical
  thickness in the solar atmosphere. We discuss how using multiwavelength
  millimeter measurements can refine plasma analysis through knowledge
  of the absorption mechanisms. Here we use subband observations from
  the publicly available science verification (SV) data, while our
  methodology will also be applicable to regular ALMA data. The spectral
  resolving capacity of ALMA SV data is tested using the enhancement
  coincident with an X-ray bright point and from a plasmoid ejection
  event near active region NOAA12470 observed in Band 3 (84-116 GHz) on
  2015 December 17. We compute the interferometric brightness temperature
  light curve for both features at each of the four constituent subbands
  to find the logarithmic millimeter spectrum. We compared the observed
  logarithmic spectral gradient with the derived relationship with optical
  thickness for an isothermal plasma to estimate the structures’
  optical thicknesses. We conclude, within 90% confidence, that the
  stationary enhancement has an optical thickness between 0.02 ≤ τ
  ≤ 2.78, and that the moving enhancement has 0.11 ≤ τ ≤ 2.78,
  thus both lie near to the transition between optically thin and thick
  plasma at 100 GHz. From these estimates, isothermal plasmas with
  typical Band 3 background brightness temperatures would be expected
  to have electron temperatures of ∼7370-15300 K for the stationary
  enhancement and between ∼7440 and 9560 K for the moving enhancement,
  thus demonstrating the benefit of subband ALMA spectral analysis.

---------------------------------------------------------
Title: RADYNVERSION: Learning to Invert a Solar Flare Atmosphere
    with Invertible Neural Networks
Authors: Osborne, Christopher M. J.; Armstrong, John A.; Fletcher,
   Lyndsay
2019ApJ...873..128O    Altcode: 2019arXiv190108626O
  During a solar flare, it is believed that reconnection takes place in
  the corona followed by fast energy transport to the chromosphere. The
  resulting intense heating strongly disturbs the chromospheric structure
  and induces complex radiation hydrodynamic effects. Interpreting the
  physics of the flaring solar atmosphere is one of the most challenging
  tasks in solar physics. Here we present a novel deep-learning approach,
  an invertible neural network, to understanding the chromospheric
  physics of a flaring solar atmosphere via the inversion of observed
  solar line profiles in Hα and Ca II λ8542. Our network is trained
  using flare simulations from the 1D radiation hydrodynamic code RADYN as
  the expected atmosphere and line profile. This model is then applied
  to single pixels from an observation of an M1.1 solar flare taken
  with the Swedish 1 m Solar Telescope/CRisp Imaging SpectroPolarimeter
  instrument just after the flare onset. The inverted atmospheres obtained
  from observations provide physical information on the electron number
  density, temperature, and bulk velocity flow of the plasma throughout
  the solar atmosphere ranging from 0 to 10 Mm in height. The density and
  temperature profiles appear consistent with the expected atmospheric
  response, and the bulk plasma velocity provides the gradients needed
  to produce the broad spectral lines while also predicting the expected
  chromospheric evaporation from flare heating. We conclude that we have
  taught our novel algorithm the physics of a solar flare according
  to RADYN and that this can be confidently used for the analysis of
  flare data taken in these two wavelengths. This algorithm can also be
  adapted for a menagerie of inverse problems providing extremely fast
  (∼10 μs) inversion samples.

---------------------------------------------------------
Title: Photochemistry in Saturn's Atmosphere: Ring Shadow and Ring
    Reflection
Authors: Edgington, S. G.; Atreya, S. K.; Wilson, E. H.; Baines,
   K. H.; West, R. A.; Bjoraker, G. L.; Fletcher, L. N.; Momary, T. W.
2019LPI....50.3053E    Altcode:
  This work studies the generation and variation of haze in Saturn's
  atmosphere and the chemistry and solar-seasonal insolation that
  modulates it.

---------------------------------------------------------
Title: The Europa Imaging System (EIS): High-Resolution, 3-D Insight
    into Europa's Geology, Ice Shell, and Potential for Current Activity
Authors: Turtle, E. P.; McEwen, A. S.; Collins, G. C.; Daubar,
   I. J.; Ernst, C. M.; Fletcher, L.; Hansen, C. J.; Hawkins, S. E.;
   Hayes, A. G.; Humm, D.; Hurford, T. A.; Kirk, R. L.; Kutsop, N.;
   Barr Mlinar, A. C.; Nimmo, F.; Patterson, G. W.; Phillips, C. B.;
   Pommerol, A.; Prockter, L.; Quick, L. C.; Reynolds, E. L.; Slack,
   K. A.; Soderblom, J. M.; Sutton, S.; Thomas, N.; Bland, M.
2019LPI....50.3065T    Altcode:
  Cameras to observe / Europa's fractured landscapes / Ice shell
  mysteries.

---------------------------------------------------------
Title: Radynversion: Solar atmospheric properties during a solar flare
Authors: Osborne, Christopher M. J.; Armstrong, John A.; Fletcher,
   Lyndsay
2019ascl.soft02008O    Altcode:
  Radynversion infers solar atmospheric properties during a solar
  flare. The code is based on an Invertible Neural Network (INN) that
  is trained to learn an approximate bijective mapping between the
  atmospheric properties of electron density, temperature, and bulk
  velocity (all as a function of altitude), and the observed Hα and Ca
  II λ8542 line profiles. As information is lost in the forward process
  of radiation transfer, this information is injected back into the model
  during the inverse process by means of a latent space; the training
  allows this latent space to be filled using an n-dimensional unit
  Gaussian distribution, where n is the dimensionality of the latent
  space. The code is based on a model trained by simulations made by
  RADYN, a 1D non-equilibrium radiation hydrodynamic model with good
  optically thick radiation treatment that does not consider magnetic
  effects.

---------------------------------------------------------
Title: The Spectral Content of SDO/AIA 1600 and 1700 Å Filters from
    Flare and Plage Observations
Authors: Simões, Paulo J. A.; Reid, Hamish A. S.; Milligan, Ryan O.;
   Fletcher, Lyndsay
2019ApJ...870..114S    Altcode: 2018arXiv180801488S
  The strong enhancement of the ultraviolet emission during solar flares
  is usually taken as an indication of plasma heating in the lower solar
  atmosphere caused by the deposition of the energy released during
  these events. Images taken with broadband ultraviolet filters by the
  Transition Region and Coronal Explorer and Atmospheric Imaging Assembly
  (AIA; 1600 and 1700 Å) have revealed the morphology and evolution of
  flare ribbons in great detail. However, the spectral content of these
  images is still largely unknown. Without knowledge of the spectral
  contribution to these UV filters, the use of these rich imaging data
  sets is severely limited. Aiming to solve this issue, we estimate
  the spectral contributions of the AIA UV flare and plage images using
  high-resolution spectra in the range 1300-1900 Å from the Skylab NRL
  SO82B spectrograph. We find that the flare excess emission in AIA 1600
  Å is dominated by the C IV 1550 Å doublet (26%), Si I continua (20%),
  with smaller contributions from many other chromospheric lines such
  as C I 1561 and 1656 Å multiplets, He II 1640 Å, and Si II 1526 and
  1533 Å. For the AIA 1700 Å band, the C I 1656 Å multiplet is the
  main contributor (38%), followed by He II 1640 (17%), and accompanied
  by a multitude of other, weaker chromospheric lines, with minimal
  contribution from the continuum. Our results can be generalized to
  state that the AIA UV flare excess emission is of chromospheric origin,
  while plage emission is dominated by photospheric continuum emission
  in both channels.

---------------------------------------------------------
Title: Water and Volatiles in the Outer Solar System
Authors: Grasset, O.; Castillo-Rogez, J.; Guillot, T.; Fletcher,
   L. N.; Tosi, F.
2019dwpp.book..191G    Altcode:
  No abstract at ADS

---------------------------------------------------------
Title: Continuum emission enhancements and penumbral changes observed
    during flares by IRIS, ROSA, and Hinode
Authors: Zuccarello, F.; Guglielmino, S. L.; Capparelli, V.;
   Mathioudakis, M.; Keys, P.; Fletcher, L.; Criscuoli, S.; Falco, M.;
   Murabito, M.
2019NCimC..42...13Z    Altcode: 2019arXiv190101732Z
  In this paper we describe observations acquired by satellite instruments
  ( Hinode/SOT and IRIS) and ground-based telescopes (ROSA@DST) during
  two consecutive C7.0 and X1.6 flares occurred in active region NOAA
  12205 on 2014 November 7. The analysis of these data show the presence
  of continuum enhancements during the evolution of the events, observed
  both in ROSA images and in IRIS spectra. Moreover, we analyze the role
  played by the evolution of the δ sunspots of the active region in the
  flare triggering, indicating the disappearance of a large portion of
  penumbra around these sunspots.

---------------------------------------------------------
Title: Contemporaneous VLA and ALMA observations of Jupiter during
    the Juno mission
Authors: De Pater, I.; Sault, R. J.; Mockel, C.; Moullet, A.; Butler,
   B. J.; Fletcher, L. N.; deBoer, D.; Wong, M. H.; Orton, G.; Janssen,
   M. A.; Cosentino, R.; Villard, E.; Bjoraker, G. L.
2018AGUFM.P33F3897D    Altcode:
  In early January 2017, between Juno's perijoves PJ3 and PJ4 (near
  its originally planned PJ8) we imaged Jupiter with the Very Large
  Array (VLA) at 8-12 GHz and with ALMA at 100 and 230 GHz. We will
  inter-compare these datasets, and compare them with VLA data obtained
  in 2014, and the Juno Microwave Radiometer (MWR) data obtained during
  PJ1. We will further compare these data with contemporaneous HST,
  Gemini 5-micron, near-IR IRTF, and mid-IR VLT and Subaru data. The
  prior VLA maps of Jupiter, obtained in 2014 at frequencies between 3
  and 37 GHz, were analyzed in detail to derive the ammonia abundance as
  a function of depth and latitude for our longitude-smeared maps. With
  these ammonia profiles, we can match the nadir brightness temperatures
  as measured by Juno/MWR during PJ1 very well. Although our VLA ammonia
  profiles match the NH3 profiles derived from the Juno data by the Juno
  team reasonably well in the Equatorial Zone and North Equatorial Belt,
  there are noticeable differences at other latitudes. <P />References:
  <P />de Pater et al., 2016. Science, 352, 1198-1201. <P />de
  Pater et al., 2018. Icarus, submitted. <P />Li et al., 2017. GRL,
  10.1002/2017GL073159.

---------------------------------------------------------
Title: Meeting contribution: Exploring the weather of the giant
    planets via professional-amateur collaboration
Authors: Fletcher, L.
2018JBAA..128..374F    Altcode:
  No abstract at ADS

---------------------------------------------------------
Title: Mid-infrared spectra and images of Jupiter's auroral regions
    during perijoves 11 - 15
Authors: Sinclair, J. A.; Orton, G.; Greathouse, T. K.; Giles, R.;
   Kasaba, Y.; Sato, T. M.; Watanabe, H.; Tao, C.; Gladstone, R.; Clark,
   G. B.; Fletcher, L. N.; Moses, J. I.; Irwin, P. G.; Tabataba-Vakili, F.
2018AGUFM.P33F3892S    Altcode:
  Energetic charged particles from the Jovianmagnetosphere penetrate
  the atmosphere in the polar regions and deposit their energy into
  the neutral atmosphere to pressures as deep as the 1-mbar level
  (or approximately 150 km above the 1 bar level). The resulting
  precipitation, ion drag and joule heating warms the neutral stratosphere
  and modifies the hydrocarbon chemistry (e.g. Sinclair et al., 2017a,
  Icarus 292, 182-207, Sinclair et al., 2018, Icarus 300, 305-326). This
  coupling of the neutral stratosphere and the magnetosphere can be
  sensed by the mid-infrared emission of stratospheric CH<SUB>4</SUB>,
  C<SUB>2</SUB>H<SUB>2</SUB>, C<SUB>2</SUB>H<SUB>4</SUB>and further
  hydrocarbon species. Mid-infrared measurements of Jupiter's auroral
  regions were performed near-contemporaneously with perijoves (PJ)
  11-15 in order to sense the atmosphere-magnetosphere coupling
  at stratospheric altitudes, a region poorly sampled by Juno's
  instrumentation. High-spatial resolution 7.8-μm images of Jupiter's
  stratospheric CH<SUB>4</SUB>emission were measured by Subaru-COMICS
  (Kataza et al., 2000, Optical and IR Telescope Instrumentation and
  Detectors, 4008 1144-1152) on March 31-April 1<SUP>st</SUP>(PJ12),
  May 24-25<SUP>th</SUP>(PJ13). The morphology of CH<SUB>4</SUB>auroral
  emission will be compared with Juno and HST measurements of the
  ultraviolet auroral emission to explore the correlation of high UV
  color ratios, inferred to be driven by lateral Pedersen currents,
  with heating of the neutrals. High-spectral resolution IRTF-TEXES
  (Lacy et al., 2002, PASP 114, 153-168) measurements of CH<SUB>4</SUB>,
  C<SUB>2</SUB>H<SUB>2</SUB>, C<SUB>2</SUB>H<SUB>4</SUB>emission were
  acquired on February 9-12 (PJ11) and July 11-16 (PJ14). A retrieval
  analysis will be conducted to derive three-dimensional maps (altitude,
  latitude, longitude) of temperature and hydrocarbon abundances at
  Jupiter's high latitudes. New constraints on the vertical profile of
  CH<SUB>4</SUB>in Jupiter's auroral region (Clark et al., 2018, under
  review) will be adopted in this analysis to explore the effects on
  retrieved parameters. Both datasets will be compared with measurements
  supporting previous perijoves and the approach phase of Juno to Jupiter
  to explore the longer-term variability of the auroral stratosphere.

---------------------------------------------------------
Title: Notes and News: 'New Views of Jupiter': Pro-Am collaborations
    during and beyond the NASA Juno mission
Authors: Rogers, J. H.; Fletcher, L.
2018JBAA..128..321R    Altcode:
  An illustrated report of a pro-am workshop hosted by the Royal
  Astronomical Society in Burlington House, London, on 2018 May 10-11
  and on the second day in the equally handsome and historic rooms of
  the Linnean Society next door. It was organised by Dr John Rogers
  (BAA) and Dr Leigh Fletcher (University of Leicester), as a follow-up
  to the workshop in Nice two years earlier [BAA Journal vol.126 p.199,
  2016]. The workshop was principally funded by EuroPlanet with funding
  from the European Union, with a contribution from the European Research
  Council, and the RAS provided the venue and staff free of charge.

---------------------------------------------------------
Title: Photochemistry in Saturn's Atmosphere: Ring Shadow and Ring
    Reflection
Authors: Edgington, S. G.; Atreya, S. K.; Wilson, E. H.; Baines,
   K. H.; West, R. A.; Bjoraker, G. L.; Fletcher, L. N.; Momary, T.
2018AGUFM.P43E3814E    Altcode:
  After over thirteen years in Saturn orbit, Cassini observed for half
  a Saturnian year. During this epoch, the ring shadow moved from its
  northernmost extent to its southernmost. Acting like Venetian blinds,
  the rings would modulate both ultraviolet and visible sunlight
  penetrating through the rings. At the same time, both visible and
  ultraviolet light would be reflected from the sunlit side of the rings
  on the already sunlit hemisphere. Total insolation at any particular
  latitude would vary depending on Saturn's axis relative to the Sun,
  the optical thickness of each ring system, and ring reflectivity. These
  factors effectively magnify seasonal effects due to axial tilt alone,
  further influencing photochemical cycles and haze generation. This
  effect was observed with the transformation of the northern hemisphere
  from a relatively clear, blue Rayleigh-scattering atmosphere in 2004
  to a smoggy, salmon color over the mission. We report on insolation
  over Saturn's disk accounting for axis tilt, ring transmission and
  reflectance, and solar cycle over Voyager and Cassini epochs. Impact on
  photolysis of key hydrocarbons in Saturn's thermosphere, stratosphere,
  and troposphere are explored and limits on production-loss rates
  and abundance of long-lived photochemical products leading to
  haze formation are placed. We assess the impact of insolation on a
  disequilibrium species (e.g. phosphine) whose presence in the upper
  troposphere can be used as a tracer of convective processes in the
  deeper atmosphere. Analysis of Cassini's CIRS, UVIS, and VIMS datasets
  are used to provide constrains on evolving haze content. Comparison
  of hazes at mid-latitudes will be contrasted to those within Saturn's
  hexagonal jet stream to understand evolution from a hazeless atmosphere
  to a hazy one. We explore how this jet stream acts like a barrier to
  transport, isolating the north polar region from photochemical hazes
  generate outside of it. <P />The research described in this paper
  was carried out in part at the Jet Propulsion Laboratory, California
  Institute of Technology, under a contract with the National Aeronautics
  and Space Administration. Copyright 2018 California Institute of
  Technology. Government sponsorship is acknowledged.

---------------------------------------------------------
Title: The development of lower-atmosphere turbulence early in a
    solar flare
Authors: Jeffrey, N. L. S.; Fletcher, L.; Labrosse, N.; Simões,
   P. J. A.
2018SciA....4.2794J    Altcode: 2018arXiv181209906J
  We present the first observational study of the onset and evolution of
  solar flare turbulence in the lower solar atmosphere on an unprecedented
  time scale of 1.7 s using the Interface Region Imaging Spectrograph
  observing plasma at a temperature of 80,000 K. At this time resolution,
  nonthermal spectral line broadening, indicating turbulent velocity
  fluctuations, precedes the flare onset at this temperature and is
  coincident with net blue-shifts. The broadening decreases as the flare
  brightens and then oscillates with a period of 10 s. These observations
  are consistent with turbulence in the lower solar atmosphere at the
  flare onset, heating that region as it dissipates. This challenges the
  current view of energy release and transport in the standard solar flare
  model, suggesting that turbulence partly heats the lower atmosphere.

---------------------------------------------------------
Title: Spatially-Resolved Spectroscopy of the Ice Giants Atmospheres:
    Clouds, Seasonal Changes, and the Future in IR with JWST MIRI
Authors: Roman, M. T.; Fletcher, L. N.; Banfield, D. J.; Gierasch,
   P. J.
2018AGUFM.P31B..05R    Altcode:
  We present results from an analysis of spatially-resolved near-IR
  spectra of Uranus and Neptune and compare aerosol distributions and
  observed changes over a period of six years. Data were acquired
  from 2001 to 2007 using the 200-inch ( 5.1m) Hale Telescope and
  the Palomar High Angular Resolution Observer (PHARO) near-infrared
  adaptive optics (AO) camera system. Latitudinal variations in
  aerosols are interpreted in context of notional circulation models,
  while temporal changes suggest potential seasonal effects. We infer
  significant reduction in aerosol scattering optical thickness in
  southern latitudes between 2001 and 2007 on Uranus, in agreement with
  trends reported in studies covering part of the same period using
  different data and retrieval algorithms. For Neptune, latitudinal
  variations in the higher aerosols are consistent with upwelling at
  mid-latitudes, consistent with circulation inferred from IR spectra,
  with the greatest aerosol abundances in peaking in 2002 before reaching
  a minimum in 2006/2007. Best fits to both planets are consistent with
  polar depletion of methane in the tropopause (&gt;2 bar). Stratospheric
  methane abundances are poorly constrained in the near IR, but generally
  consistent with lower values on Uranus and values near saturation
  Neptune. <P />A far greater understanding of the cloud level and
  stratosphere will come with observations from the James Webb Space
  Telescope (JWST). We look ahead to how the JWST MIRI instrument will
  provide global, spatially resolved 5-30 μm spectroscopy of Uranus
  and Neptune, thus providing an unprecedented picture of atmospheric
  temperatures, winds, and composition from the troposphere to the
  stratosphere. MIRI spectra will offer unique constraints for radiative,
  dynamical, and chemical models of the ice giant atmospheres and lead
  the way for future spacecraft missions.

---------------------------------------------------------
Title: Cyclone-related lightning near Juno's 6th orbit
Authors: Wong, M. H.; Brown, S. T.; Fletcher, L. N.; Bjoraker, G. L.;
   De Pater, I.; Simon, A. A.
2018AGUFM.P33F3891W    Altcode:
  The densest cluster of Juno MWR lightning strikes on perijove
  6 (PJ6) occurred near 49 N planetographic latitude (Brown et
  al. 2018; DOI:10.1038/s41586-018-0156-5). Hubble imaging reveals
  a cyclonic vortex at this location. <P />Assuming the results
  of Romps et al. (2014; DOI:10.1126/science.1259100) apply to
  Jupiter as well as the Earth, Jupiter's cyclones are likely to be
  heavily-precipitating systems, explaining observations of depleted
  volatiles in microwave spectral imaging data (de Pater et al. 2016;
  DOI:10.1126/science.aaf2210). Ground-based thermal infrared imaging
  and spectra show that anomalies in temperature, composition, and
  cloud structure are common in low-latitude cyclonic vortices of
  different types. These infrared data were acquired in early 2017
  using VLT/VISIR, Gemini NIRI, Keck NIRSPEC, and IRTF iSHELL. Hubble
  imaging data constrain some clouds to be deeper than 4 bar (presumably
  water clouds), particularly in the PJ6 cyclone with strong lightning
  activity. Large cyclones feature differences in high-altitude particle
  properties relative to their surroundings, consistent with downwelling
  and sublimation of haze particles in the upper troposphere. Warm, dry,
  and less-hazy conditions in the upper part of cyclones are consistent
  with downwelling aloft, while deep water clouds and lightning are
  consistent with upwelling at depth, precisely the inverse of the
  circulation within anticyclonic vortices according to Marcus et
  al. (2013; DOI:10.1115/1.4007666). This vortex structure suggests that
  midplanes of cyclones with lightning activity lie between the upper
  troposphere and the water cloud layer. Cyclones without water clouds
  and lightning may exist if their midplanes lie deeper than the water
  cloud layer.

---------------------------------------------------------
Title: Detection of Three-minute Oscillations in Full-disk Lyman-alpha
    Emission during a Solar Flare
Authors: Milligan, Ryan O.; Fleck, Bernhard; Ireland, Jack; Fletcher,
   Lyndsay; Dennis, Brian R.
2018csc..confE..36M    Altcode:
  In a recent study of spatially-integrated Lyman-alpha line emission
  (Lya, 1216A) from GOES/EUVS, we detected the presence of acoustic
  3-minute oscillations during an X-class solar flare. Similar
  periodicities were also found - in phase - in Lyman continuum data from
  SDO/EVE, and the 1600A and 1700A channels on SDO/AIA. The implication
  is that the chromosphere responds dynamically at its acoustic cutoff
  frequency to an impulsive injection of energy. Since the 3-minute
  period was not detected at hard X-ray energies in RHESSI data we can
  state that this 3-minute oscillation does not depend on the rate of
  energisation of non-thermal electrons. This finding suggests that
  chromospheric mechanical energy should be included in the flare
  energy budget, and that fluctuations in Lya emission may influence
  the composition and dynamics of planetary atmospheres during periods
  of high activity. Knowledge of the behaviour of this emission during
  flares could be important when interpreting future science results
  from the EUI instrument on Solar Orbiter which will obtain high cadence
  images in Lya.

---------------------------------------------------------
Title: The spectral content of SDO/AIA 1600 and 1700 A filters from
    flare and plage observations
Authors: Simoes, Paulo; Reid, Hamish; Milligan, Ryan; Fletcher, Lyndsay
2018csc..confE.125S    Altcode:
  The strong enhancement of the ultraviolet emission during solar
  flares is usually taken as an indication of plasma heating in the
  low solar atmosphere caused by the deposition of the energy released
  during these events. Images taken with broadband ultraviolet filters
  by the Transition Region and Coronal Explorer (TRACE) and Atmospheric
  Imaging Assembly (AIA 1600 and 1700 Å) have revealed the morphology
  and evolution of flare ribbons in great detail. However, the spectral
  content of these images is still largely unknown. Without the knowledge
  of the spectral contribution to these UV filters, the use of these rich
  imaging datasets is severely limited. Aiming to solve this issue, we
  estimate the spectral contributions of the AIA UV flare and plage images
  using high-resolution spectra in the range 1300 to 1900 Å from the
  Skylab NRL SO82B spectrograph. We find that the flare excess emission in
  AIA 1600 Å is composed of the C IV 1550 Å doublet (26%), Si I continua
  (20%), with smaller contributions from many other chromospheric lines
  such as C I 1561 and 1656 Å multiplets, He II 1640 Å, Si II 1526 and
  1533 Å. For the AIA 1700 Å band, C I 1656 Å multiplet is the main
  contributor (38%), followed by He II 1640 (17%), and accompanied by a
  multitude of other chromospheric lines, with minimal contribution from
  the continuum. Our results can be generalized to state that the AIA UV
  flare excess emission is of chromospheric origin, while plage emission
  is dominated by photospheric continuum emission in both channels.

---------------------------------------------------------
Title: Characterization of Mesoscale Waves in the Jupiter NEB by
    Jupiter InfraRed Auroral Mapper on board Juno
Authors: Adriani, A.; Moriconi, M. L.; Altieri, F.; Sindoni, G.;
   Ingersoll, A. P.; Grassi, D.; Mura, A.; Atreya, S. K.; Orton, G.;
   Lunine, J. I.; Fletcher, L. N.; Simon, A. A.; Melin, H.; Tosi, F.;
   Cicchetti, A.; Noschese, R.; Sordini, R.; Levin, S.; Bolton, J.;
   Plainaki, C.; Olivieri, A.
2018AJ....156..246A    Altcode:
  In 2017, the Jupiter InfraRed Auroral Mapper (JIRAM), on board the
  NASA-ASI Juno mission, observed a wide longitude region (50° W-80° E
  in System III) that was perturbed by a wave pattern centered at 15° N
  in the Jupiter’s North Equatorial Belt (NEB). We analyzed JIRAM data
  acquired on 2017 July 10 using the M-channel and on 2017 February 2 with
  the spectrometer. The two observations occurred at different times and
  at slightly different latitudes. The waves appear as clouds blocking
  the deeper thermal emission. The wave crests are oriented north-south,
  and the typical wave packet contains 10 crests and 10 troughs. We used
  Fourier analysis to rigorously determine the wavenumbers associated
  with the observed patterns at a confidence level of 90%. Wavelet
  analysis was also used to constrain the spatial localization of the
  largest energies involved in the process and determine the wavelengths
  carrying the major contribution. We found wavelengths ranging from 1400
  to 1900 km, and generally decreasing toward the west. Where possible,
  we also computed a vertical location of the cloud pressure levels
  from the inversion of the spectral radiances measured by the JIRAM
  spectrometer. The waves were detected at pressure levels consistent with
  the NH<SUB>3</SUB> as well as NH<SUB>4</SUB>SH clouds. Phase velocities
  could not be determined with sufficient confidence to discriminate
  whether the alternating crests and troughs are a propagating wave or
  a manifestation of a fluid dynamical instability.

---------------------------------------------------------
Title: A hexagon in Saturn's northern stratosphere surrounding the
    emerging summertime polar vortex
Authors: Fletcher, L. N.; Orton, G. S.; Sinclair, J. A.; Guerlet,
   S.; Read, P. L.; Antuñano, A.; Achterberg, R. K.; Flasar, F. M.;
   Irwin, P. G. J.; Bjoraker, G. L.; Hurley, J.; Hesman, B. E.; Segura,
   M.; Gorius, N.; Mamoutkine, A.; Calcutt, S. B.
2018NatCo...9.3564F    Altcode: 2018arXiv180900572F
  Saturn's polar stratosphere exhibits the seasonal growth and dissipation
  of broad, warm vortices poleward of 75° latitude, which are strongest
  in the summer and absent in winter. The longevity of the exploration
  of the Saturn system by Cassini allows the use of infrared spectroscopy
  to trace the formation of the North Polar Stratospheric Vortex (NPSV),
  a region of enhanced temperatures and elevated hydrocarbon abundances at
  millibar pressures. We constrain the timescales of stratospheric vortex
  formation and dissipation in both hemispheres. Although the NPSV formed
  during late northern spring, by the end of Cassini's reconnaissance
  (shortly after northern summer solstice), it still did not display the
  contrasts in temperature and composition that were evident at the south
  pole during southern summer. The newly formed NPSV was bounded by a
  strengthening stratospheric thermal gradient near 78°N. The emergent
  boundary was hexagonal, suggesting that the Rossby wave responsible
  for Saturn's long-lived polar hexagon—which was previously expected
  to be trapped in the troposphere—can influence the stratospheric
  temperatures some 300 km above Saturn's clouds.

---------------------------------------------------------
Title: Modeling of the Hydrogen Lyman Lines in Solar Flares
Authors: Brown, Stephen A.; Fletcher, Lyndsay; Kerr, Graham S.;
   Labrosse, Nicolas; Kowalski, Adam F.; De La Cruz Rodríguez, Jaime
2018ApJ...862...59B    Altcode: 2018arXiv180703373B
  The hydrogen Lyman lines (91.2 nm &lt; λ &lt; 121.6 nm) are significant
  contributors to the radiative losses of the solar chromosphere, and
  they are enhanced during flares. We have shown previously that the Lyman
  lines observed by the Extreme Ultraviolet Variability instrument onboard
  the Solar Dynamics Observatory exhibit Doppler motions equivalent
  to speeds on the order of 30 km s<SUP>-1</SUP>. However, contrary to
  expectations, both redshifts and blueshifts were present and no dominant
  flow direction was observed. To understand the formation of the Lyman
  lines, particularly their Doppler motions, we have used the radiative
  hydrodynamic code, RADYN, along with the radiative transfer code, RH,
  to simulate the evolution of the flaring chromosphere and the response
  of the Lyman lines during solar flares. We find that upflows in the
  simulated atmospheres lead to blueshifts in the line cores, which
  exhibit central reversals. We then model the effects of the instrument
  on the profiles, using the Extreme Ultraviolet Variability Experiment
  (EVE) instrument's properties. What may be interpreted as downflows
  (redshifted emission) in the lines, after they have been convolved
  with the instrumental line profile, may not necessarily correspond to
  actual downflows. Dynamic features in the atmosphere can introduce
  complex features in the line profiles that will not be detected by
  instruments with the spectral resolution of EVE, but which leave more
  of a signature at the resolution of the Spectral Investigation of the
  Coronal Environment instrument onboard the Solar Orbiter.

---------------------------------------------------------
Title: Observing turbulence early in a solar flare with the high
    time resolution of IRIS
Authors: Jeffrey, Natasha; Simões, Paulo; Fletcher, Lyndsay;
   Labrosse, Nicolas
2018cosp...42E1609J    Altcode:
  Wave and turbulent dissipation play a key role in the transfer of energy
  in magnetized plasmas. Here we report the first high time-resolution,
  &lt;2 s, spectroscopic study of flare turbulence in the lower solar
  atmosphere, using the Interface Region Imaging Spectrograph (IRIS). We
  observe the line Si IV 1402.77 Å, formed at a transition region
  temperature of 80000 K, at the eastern flare footpoint, over a region
  of &lt;0.3” during the flare duration. The non-thermal broadening
  indicates turbulent motions with velocities of 60-70 km/s. The line
  broadening rises sharply, and precedes the flare onset as indicated
  by its impulsive radiation signatures in Si IV intensity, extreme
  ultraviolet (EUV) and X-rays. The &lt;2 s cadence shows that the
  line broadening oscillates with a period of ∼10 s before its decay,
  coinciding with motions in the Si IV line centroid position. The results
  are consistent with the dissipation of turbulent energy in the lower
  atmosphere, early in the solar flare, and before the flare brightening.

---------------------------------------------------------
Title: Spectroscopic measurements of the ion velocity distribution
    at the base of the fast solar wind
Authors: Jeffrey, Natasha; Savin, Daniel W.; Hahn, Michael; Fletcher,
   Lyndsay
2018cosp...42E1608J    Altcode:
  In situ measurements of the fast solar wind reveal non-thermal
  distributions of electrons, protons and, minor ions extending from
  0.3 AU to the heliopause. The physical mechanisms responsible for
  these non-thermal properties and the location where these properties
  originate remain open questions. Here we present spectroscopic evidence,
  from extreme ultraviolet spectroscopy, that the velocity distribution
  functions (VDFs) of minor ions are already non-Gaussian at the base
  of the fast solar wind in a coronal hole, at altitudes of &lt; 1.1
  R_{⊙}. Analysis of Fe, Si, and Mg spectral lines reveal a peaked
  line-shape core and broad wings that can be characteristed by a kappa
  VDF. A kappa distribution fit gives very small kappa indices off-limb
  of κ≈ 1.9-2.5, indicating either (a) ion populations far from
  thermal equilibrium, (b) fluid motions such as non-Gaussian turbulent
  fluctuations or non-uniform wave motions, or (c) some combination
  of both. These observations provide important empirical constraints
  for the source region of the fast solar wind and for the theoretical
  models of the different acceleration, heating, and energy deposition
  processes therein. To the best of our knowledge, this is the first
  time that the ion VDF in the fast solar wind has been probed so close
  to its source region. The findings are also a timely precursor to the
  upcoming 2018 launch of the Parker Solar Probe, which will provide the
  closest in situ measurements of the solar wind at approximately 0.04 AU
  (8.5 solar radii).

---------------------------------------------------------
Title: Thermal Emission From Saturn's Polar Cyclones
Authors: Achterberg, R. K.; Flasar, F. M.; Bjoraker, G. L.; Hesman,
   B. E.; Gorius, N. J. P.; Mamoutkine, A. A.; Fletcher, L. N.; Segura,
   M. E.; Edgington, S. G.; Brooks, S. M.
2018GeoRL..45.5312A    Altcode:
  We have used data from the Cassini Composite Infrared Spectrometer to
  map the temperatures in Saturn's polar cyclones at the highest spatial
  resolution obtained during the Cassini mission. We find temperature
  contrasts of 7 K in the upper troposphere within 1.4° of both poles,
  roughly 50 percent larger than earlier measurements at lower spatial
  resolution. The polar hot spots weaken with depth, disappearing near
  500 mbar. In the stratosphere, the polar hot spot becomes broader,
  extending 4° from the poles, and weakens with altitude disappearing
  near 1 mbar. A thermal relaxation model shows that the tropospheric
  hot spot is consistent with adiabatic heating from subsidence with
  a vertical velocity of about -0.05 mm/s above 500 mbar. The observed
  temperature gradients imply that the winds in the polar cyclone decay
  with increasing altitude over roughly three pressure scale heights
  above the 200-mbar level.

---------------------------------------------------------
Title: Scientific rationale for Uranus and Neptune in situ
    explorations
Authors: Mousis, O.; Atkinson, D. H.; Cavalié, T.; Fletcher, L. N.;
   Amato, M. J.; Aslam, S.; Ferri, F.; Renard, J. -B.; Spilker, T.;
   Venkatapathy, E.; Wurz, P.; Aplin, K.; Coustenis, A.; Deleuil, M.;
   Dobrijevic, M.; Fouchet, T.; Guillot, T.; Hartogh, P.; Hewagama, T.;
   Hofstadter, M. D.; Hue, V.; Hueso, R.; Lebreton, J. -P.; Lellouch,
   E.; Moses, J.; Orton, G. S.; Pearl, J. C.; Sánchez-Lavega, A.;
   Simon, A.; Venot, O.; Waite, J. H.; Achterberg, R. K.; Atreya, S.;
   Billebaud, F.; Blanc, M.; Borget, F.; Brugger, B.; Charnoz, S.;
   Chiavassa, T.; Cottini, V.; d'Hendecourt, L.; Danger, G.; Encrenaz,
   T.; Gorius, N. J. P.; Jorda, L.; Marty, B.; Moreno, R.; Morse, A.;
   Nixon, C.; Reh, K.; Ronnet, T.; Schmider, F. -X.; Sheridan, S.; Sotin,
   C.; Vernazza, P.; Villanueva, G. L.
2018P&SS..155...12M    Altcode: 2017arXiv170800235M
  The ice giants Uranus and Neptune are the least understood class
  of planets in our solar system but the most frequently observed
  type of exoplanets. Presumed to have a small rocky core, a deep
  interior comprising ∼70% heavy elements surrounded by a more
  dilute outer envelope of H<SUB>2</SUB> and He, Uranus and Neptune
  are fundamentally different from the better-explored gas giants
  Jupiter and Saturn. Because of the lack of dedicated exploration
  missions, our knowledge of the composition and atmospheric processes
  of these distant worlds is primarily derived from remote sensing
  from Earth-based observatories and space telescopes. As a result,
  Uranus's and Neptune's physical and atmospheric properties remain
  poorly constrained and their roles in the evolution of the Solar System
  not well understood. Exploration of an ice giant system is therefore
  a high-priority science objective as these systems (including the
  magnetosphere, satellites, rings, atmosphere, and interior) challenge
  our understanding of planetary formation and evolution. Here we
  describe the main scientific goals to be addressed by a future in
  situ exploration of an ice giant. An atmospheric entry probe targeting
  the 10-bar level, about 5 scale heights beneath the tropopause, would
  yield insight into two broad themes: i) the formation history of the
  ice giants and, in a broader extent, that of the Solar System, and ii)
  the processes at play in planetary atmospheres. The probe would descend
  under parachute to measure composition, structure, and dynamics, with
  data returned to Earth using a Carrier Relay Spacecraft as a relay
  station. In addition, possible mission concepts and partnerships are
  presented, and a strawman ice-giant probe payload is described. An
  ice-giant atmospheric probe could represent a significant ESA
  contribution to a future NASA ice-giant flagship mission.

---------------------------------------------------------
Title: The Origin of White Light Flares: A parameter study of standard
    model solar flare RHD Simulations
Authors: Kerr, Graham Stewart; de Aguiar Simoes, Paulo Jose; Fletcher,
   Lyndsay; Allred, Joel C.; Kowalski, Adam F.
2018tess.conf30490K    Altcode:
  The bulk of the enhanced radiation emitted during solar flares
  originates from the lower atmosphere, making it a crucial region for
  understanding energy and radiation transport during flares. Of the
  radiation emitted from the lower atmosphere a significant contribution
  is from enhancements to the optical continuum (white light flares;
  WLFs). There is still no consensus regarding the emission mechanism
  responsible for WLFs, in part due to the paucity of broadband WLF
  spectra, leading to ambiguity. Two commonly proposed mechanisms are
  optically thin recombination radiation in the chromosphere resulting
  from overionisation during the flare or optically thick radiation from
  the photosphere/upper photosphere resulting from enhanced H- opacity
  (an enhanced blackbody spectrum). Each mechanism can impose strong
  constraints on models of energy transport. Of course a combination of
  mechanisms is also possible. In the standard flare model, energy is
  transported to the chromosphere via a beam of non-thermal electrons. To
  address how WLFs would be produced in this standard model we performed
  a parameter study, simulating 43 flares using RADYN, a radiation
  hydrodynamics flare code. This study covered a range of typical
  non-thermal electron beam distributions and energy fluxes. It was
  found that in all cases the peak flare contribution to WLFs originated
  in the upper chromosphere as a result of recombinations. For harder
  non-thermal electron distributions there was also a non-negligible
  contribution of H- emission from the lower chromosphere and upper
  photosphere owing to an extended region of increased electron density
  (itself resulting from stronger, more deeply penetrating, non-thermal
  collisional ionisation rates). From this we predict that flares with a
  harder non-thermal electron distribution may exhibit a larger vertical
  extent when viewed on the limb. We were unable to simulate solely
  optically thick sources of WLFs. Our simulated WLF spectra are in
  good agreement with recent observations. Not all of our simulations
  resulted in an observable WLF. In lower energy simulations, flare
  energy input resulted in an enhanced opacity in the upper atmosphere
  but without sufficient ionization/recombination to produce a strong
  enough emissivity to counter the opacity. Thus we find that not all
  flares are white light flares.

---------------------------------------------------------
Title: Unambiguous Evidence of Coronal Implosions during Solar
    Eruptions and Flares
Authors: Wang, Juntao; Simões, P. J. A.; Fletcher, L.
2018ApJ...859...25W    Altcode: 2018arXiv180402354W
  In the implosion conjecture, coronal loops contract as the result
  of magnetic energy release in solar eruptions and flares. However,
  after almost two decades, observations of this phenomenon are still
  rare and most previous reports are plagued by projection effects so
  that loop contraction could be either true implosion or just a change
  in loop inclination. In this paper, to demonstrate the reality of loop
  contractions in the global coronal dynamics, we present four events
  with the continuously contracting loops in an almost edge-on geometry
  from the perspective of SDO/AIA, which are free from the ambiguity
  caused by the projection effects, also supplemented by contemporary
  observations from STEREO for examination. In the wider context of
  observations, simulations and theories, we argue that the implosion
  conjecture is valid in interpreting these events. Furthermore, distinct
  properties of the events allow us to identify two physical categories of
  implosion. One type demonstrates a rapid contraction at the beginning of
  the flare impulsive phase, as magnetic free energy is removed rapidly
  by a filament eruption. The other type, which has no visible eruption,
  shows a continuous loop shrinkage during the entire flare impulsive
  phase, which we suggest shows the ongoing conversion of magnetic free
  energy in a coronal volume. Corresponding scenarios are described that
  can provide reasonable explanations for the observations. We also
  point out that implosions may be suppressed in cases when a heavily
  mass-loaded filament is involved, possibly serving as an alternative
  account for their observational rarity.

---------------------------------------------------------
Title: Assessing the long-term variability of acetylene and ethane
    in the stratosphere of Jupiter
Authors: Melin, Henrik; Fletcher, L. N.; Donnelly, P. T.; Greathouse,
   T. K.; Lacy, J. H.; Orton, G. S.; Giles, R. S.; Sinclair, J. A.;
   Irwin, P. G. J.
2018Icar..305..301M    Altcode: 2018arXiv180100652M
  Acetylene (C<SUB>2</SUB>H<SUB>2</SUB>) and ethane
  (C<SUB>2</SUB>H<SUB>6</SUB>) are both produced in the stratosphere
  of Jupiter via photolysis of methane (CH<SUB>4</SUB>). Despite this
  common source, the latitudinal distribution of the two species is
  radically different, with acetylene decreasing in abundance towards
  the pole, and ethane increasing towards the pole. We present six years
  of NASA IRTF TEXES mid-infrared observations of the zonally-averaged
  emission of methane, acetylene and ethane. We confirm that the
  latitudinal distributions of ethane and acetylene are decoupled, and
  that this is a persistent feature over multiple years. The acetylene
  distribution falls off towards the pole, peaking at ∼ 30°N with
  a volume mixing ratio (VMR) of ∼ 0.8 parts per million (ppm) at 1
  mbar and still falling off at ± 70° with a VMR of ∼ 0.3 ppm. The
  acetylene distributions are asymmetric on average, but as we move from
  2013 to 2017, the zonally-averaged abundance becomes more symmetric
  about the equator. We suggest that both the short term changes in
  acetylene and its latitudinal asymmetry is driven by changes to the
  vertical stratospheric mixing, potentially related to propagating
  wave phenomena. Unlike acetylene, ethane has a symmetric distribution
  about the equator that increases toward the pole, with a peak mole
  fraction of ∼ 18 ppm at about ± 50° latitude, with a minimum at
  the equator of ∼ 10 ppm at 1 mbar. The ethane distribution does not
  appear to respond to mid-latitude stratospheric mixing in the same
  way as acetylene, potentially as a result of the vertical gradient of
  ethane being much shallower than that of acetylene. The equator-to-pole
  distributions of acetylene and ethane are consistent with acetylene
  having a shorter lifetime than ethane that is not sensitive to longer
  advective timescales, but is augmented by short-term dynamics, such
  as vertical mixing. Conversely, the long lifetime of ethane allows it
  to be transported to higher latitudes faster than it can be chemically
  depleted.

---------------------------------------------------------
Title: Spectroscopic Measurements of the Ion Velocity Distribution
    at the Base of the Fast Solar Wind
Authors: Jeffrey, Natasha L. S.; Hahn, Michael; Savin, Daniel W.;
   Fletcher, Lyndsay
2018EGUGA..20.1620J    Altcode:
  In situ measurements of the fast solar wind reveal non-thermal
  distributions of electrons, protons and, minor ions extending from
  0.3 AU to the heliopause. The physical mechanisms responsible for
  these non-thermal properties and the location where these properties
  originate remain open questions. Here we present spectroscopic
  evidence, from extreme ultraviolet spectroscopy, that the velocity
  distribution functions (VDFs) of minor ions are already non-Gaussian
  at the base of the fast solar wind in a coronal hole, at altitudes of
  &lt; 1.1R⊙. Analysis of Fe, Si, and Mg spectral lines reveal a peaked
  line-shape core and broad wings that can be characteristed by a kappa
  VDF. A kappa distribution fit gives very small kappa indices off-limb
  of κ ≈ 1.9 - 2.5, indicating either (a) ion populations far from
  thermal equilibrium, (b) fluid motions such as non-Gaussian turbulent
  fluctuations or non-uniform wave motions, or (c) some combination
  of both. These observations provide important empirical constraints
  for the source region of the fast solar wind and for the theoretical
  models of the different acceleration, heating, and energy deposition
  processes therein. To the best of our knowledge, this is the first
  time that the ion VDF in the fast solar wind has been probed so close
  to its source region. The findings are also a timely precursor to the
  upcoming 2018 launch of the Parker Solar Probe, which will provide the
  closest in situ measurements of the solar wind at approximately 0.04 AU
  (8.5 solar radii).

---------------------------------------------------------
Title: The quest for H_3^+ at Neptune: deep burn observations with
    NASA IRTF iSHELL
Authors: Melin, H.; Fletcher, L. N.; Stallard, T. S.; Johnson, R. E.;
   O'Donoghue, J.; Moore, L.; Donnelly, P. T.
2018MNRAS.474.3714M    Altcode: 2017arXiv171108978M
  Emission from the molecular ion H_3^+ is a powerful diagnostic
  of the upper atmosphere of Jupiter, Saturn, and Uranus, but it
  remains undetected at Neptune. In search of this emission, we present
  near-infrared spectral observations of Neptune between 3.93 and 4.00 μm
  taken with the newly commissioned iSHELL instrument on the NASA Infrared
  Telescope Facility in Hawaii, obtained 2017 August 17-20. We spent
  15.4 h integrating across the disc of the planet, yet were unable to
  unambiguously identify any H_3^+ line emissions. Assuming a temperature
  of 550 K, we derive an upper limit on the column integrated density of
  1.0^{+1.2}_{-0.8}× 10^{13} m<SUP>-2</SUP>, which is an improvement of
  30 per cent on the best previous observational constraint. This result
  means that models are overestimating the density by at least a factor
  of 5, highlighting the need for renewed modelling efforts. A potential
  solution is strong vertical mixing of polyatomic neutral species from
  Neptune's upper stratosphere to the thermosphere, reacting with H_3^+,
  thus greatly reducing the column integrated H_3^+ densities. This upper
  limit also provide constraints on future attempts at detecting H_3^+
  using the James Webb Space Telescope.

---------------------------------------------------------
Title: Spectroscopic Measurements of the Ion Velocity Distribution
    at the Base of the Fast Solar Wind
Authors: Jeffrey, Natasha L. S.; Hahn, Michael; Savin, Daniel W.;
   Fletcher, Lyndsay
2018ApJ...855L..13J    Altcode: 2018arXiv180207104J
  In situ measurements of the fast solar wind reveal non-thermal
  distributions of electrons, protons, and minor ions extending from
  0.3 au to the heliopause. The physical mechanisms responsible for
  these non-thermal properties and the location where these properties
  originate remain open questions. Here, we present spectroscopic
  evidence, from extreme ultraviolet spectroscopy, that the velocity
  distribution functions (VDFs) of minor ions are already non-Gaussian
  at the base of the fast solar wind in a coronal hole, at altitudes
  of &lt;1.1 R <SUB>⊙</SUB>. Analysis of Fe, Si, and Mg spectral
  lines reveals a peaked line-shape core and broad wings that can be
  characterized by a kappa VDF. A kappa distribution fit gives very
  small kappa indices off-limb of κ ≈ 1.9-2.5, indicating either (a)
  ion populations far from thermal equilibrium, (b) fluid motions such
  as non-Gaussian turbulent fluctuations or non-uniform wave motions,
  or (c) some combination of both. These observations provide important
  empirical constraints for the source region of the fast solar wind
  and for the theoretical models of the different acceleration, heating,
  and energy deposition processes therein. To the best of our knowledge,
  this is the first time that the ion VDF in the fast solar wind has
  been probed so close to its source region. The findings are also a
  timely precursor to the upcoming 2018 launch of the Parker Solar Probe,
  which will provide the closest in situ measurements of the solar wind
  at approximately 0.04 au (8.5 solar radii).

---------------------------------------------------------
Title: Equatorial Oscillation and Planetary Wave Activity in Saturn's
    Stratosphere Through the Cassini Epoch
Authors: Guerlet, S.; Fouchet, T.; Spiga, A.; Flasar, F. M.; Fletcher,
   L. N.; Hesman, B. E.; Gorius, N.
2018JGRE..123..246G    Altcode:
  Thermal infrared spectra acquired by Cassini/Composite InfraRed
  Spectrometer (CIRS) in limb-viewing geometry in 2015 are used to derive
  2-D latitude-pressure temperature and thermal wind maps. These maps
  are used to study the vertical structure and evolution of Saturn's
  equatorial oscillation (SEO), a dynamical phenomenon presenting
  similarities with the Earth's quasi-biennal oscillation (QBO) and
  semi-annual oscillation (SAO). We report that a new local wind maximum
  has appeared in 2015 in the upper stratosphere and derive the descent
  rates of other wind extrema through time. The phase of the oscillation
  observed in 2015, as compared to 2005 and 2010, remains consistent with
  a ∼15 year period. The SEO does not propagate downward at a regular
  rate but exhibits faster descent rate in the upper stratosphere,
  combined with a greater vertical wind shear, compared to the lower
  stratosphere. Within the framework of a QBO-type oscillation, we
  estimate the absorbed wave momentum flux in the stratosphere to be
  on the order of ∼7 × 10<SUP>-6</SUP> N m<SUP>-2</SUP>. On Earth,
  interactions between vertically propagating waves (both planetary
  and mesoscale) and the mean zonal flow drive the QBO and SAO. To
  broaden our knowledge on waves potentially driving Saturn's equatorial
  oscillation, we searched for thermal signatures of planetary waves
  in the tropical stratosphere using CIRS nadir spectra. Temperature
  anomalies of amplitude 1-4 K and zonal wave numbers 1 to 9 are
  frequently observed, and an equatorial Rossby (n = 1) wave of zonal
  wave number 3 is tentatively identified in November 2009.

---------------------------------------------------------
Title: Jupiter's auroral-related stratospheric heating and chemistry
II: Analysis of IRTF-TEXES spectra measured in December 2014
Authors: Sinclair, J. A.; Orton, G. S.; Greathouse, T. K.; Fletcher,
   L. N.; Moses, J. I.; Hue, V.; Irwin, P. G. J.
2018Icar..300..305S    Altcode:
  We present a retrieval analysis of TEXES (Texas Echelon Cross
  Echelle Spectrograph (Lacy et al., 2002)) spectra of Jupiter's high
  latitudes obtained on NASA's Infrared Telescope Facility on December
  10 and 11th 2014. The vertical temperature profile and vertical
  profiles of C<SUB>2</SUB>H<SUB>2</SUB>, C<SUB>2</SUB>H<SUB>4</SUB>
  and C<SUB>2</SUB>H<SUB>6</SUB> were retrieved at both high-northern
  and high-southern latitudes and results were compared in 'quiescent'
  regions and regions known to be affected by Jupiter's aurora in order
  to highlight how auroral processes modify the thermal structure
  and hydrocarbon chemistry of the stratosphere. In qualitative
  agreement with Sinclair et al. (2017a), we find temperatures in
  auroral regions to be elevated with respect to quiescent regions
  at two discrete pressures levels at approximately 1 mbar and 0.01
  mbar. For example, in comparing retrieved temperatures at 70°N,
  60°W (a representative quiescent region) and 70°N, 180°W (centred
  on the northern auroral oval), temperatures increase by 19.0 ± 4.2
  K at 0.98 mbar, 20.8 ± 3.9 K at 0.01 mbar but only by 8.3 ± 4.9
  K at the intermediate level of 0.1 mbar. We conclude that elevated
  temperatures at 0.01 mbar result from heating by joule resistance
  of the atmosphere and the energy imparted by electron and ion
  precipitation. However, temperatures at 1 mbar are considered to result
  either from heating by shortwave radiation of aurorally-produced haze
  particulates or precipitation of higher energy population of charged
  particles. Our former conclusion would be consistent with results of
  auroral-chemistry models, that predict the highest number densities of
  aurorally-produced haze particles at this pressure level (Wong et al.,
  2000, 2003). C<SUB>2</SUB>H<SUB>2</SUB> and C<SUB>2</SUB>H<SUB>4</SUB>
  exhibit enrichments but C<SUB>2</SUB>H<SUB>6</SUB> remains constant
  within uncertainty when comparing retrieved concentrations in the
  northern auroral region with quiescent longitudes in the same latitude
  band. At 1 mbar, C<SUB>2</SUB>H<SUB>2</SUB> increases from 278.4 ± 40.3
  ppbv at 70°N, 60°W to 564.4 ± 72.0 ppbv at 70°N, 180°W and at 0.01
  mbar, over the same longitude range at 70°N, C<SUB>2</SUB>H<SUB>4</SUB>
  increases from 0.669 ± 0.129 ppmv to 6.509 ± 0.811 ppmv. However,
  we note that non-LTE (local thermodynamic equilibrium) emission
  may affect the cores of the strongest C<SUB>2</SUB>H<SUB>2</SUB> and
  C<SUB>2</SUB>H<SUB>4</SUB> lines on the northern auroral region, which
  may be a possible source of error in our derived concentrations. We
  retrieved concentrations of C<SUB>2</SUB>H<SUB>6</SUB> at 1 mbar of
  9.03 ± 0.98 ppmv at 70°N, 60°W and 7.66 ± 0.70 ppmv at 70°N,
  180°W. Thus, C<SUB>2</SUB>H<SUB>6</SUB>'s concentration appears
  constant (within uncertainty) as a function of longitude at 70°N.

---------------------------------------------------------
Title: Detection of 3-Minute Oscillations in Full-Disk Lyman-alpha
    Emission During A Solar Flare
Authors: Milligan, R. O.; Ireland, J.; Fleck, B.; Hudson, H. S.;
   Fletcher, L.; Dennis, B. R.
2017AGUFMSH41A2739M    Altcode:
  We report the detection of chromospheric 3-minute oscillations in
  disk-integrated EUV irradiance observations during a solar flare. A
  wavelet analysis of detrended Lyman-alpha (from GOES/EUVS) and
  Lyman continuum (from SDO/EVE) emission from the 2011 February 15
  X-class flare revealed a 3-minute period present during the flare's
  main phase. The formation temperature of this emission locates this
  radiation to the flare's chromospheric footpoints, and similar behaviour
  is found in the SDO/AIA 1600A and 1700A channels, which are dominated
  by chromospheric continuum. The implication is that the chromosphere
  responds dynamically at its acoustic cutoff frequency to an impulsive
  injection of energy. Since the 3-minute period was not found at hard
  X-ray energies (50-100 keV) in RHESSI data we can state that this
  3-minute oscillation does not depend on the rate of energization of, or
  energy deposition by, non-thermal electrons. However, a second period of
  120 s found in both hard X-ray and chromospheric emission is consistent
  with episodic electron energization on 2-minute timescales. Our
  finding on the 3-minute oscillation suggests that chromospheric
  mechanical energy should be included in the flare energy budget, and
  the fluctuations in the Lyman-alpha line may influence the composition
  and dynamics of planetary atmospheres during periods of high activity.

---------------------------------------------------------
Title: Hα and Hβ emission in a C3.3 solar flare: comparison between
    observations and simulations
Authors: Zuccarello, F.; Simoes, P. J. D. A.; Capparelli, V.; Fletcher,
   L.; Romano, P.; Mathioudakis, M.; Cauzzi, G.; Carlsson, M.; Kuridze,
   D.; Keys, P.
2017AGUFMSH41A2742Z    Altcode:
  This work is based on the analysis of an extremely rare set of
  simultaneous observations of a C3.3 solar flare in the Hα and Hβ lines
  at high spatial and temporal resolution, which were acquired at the
  Dunn Solar Telescope. Images of the C3.3 flare (SOL2014-04-22T15:22)
  made at various wavelengths along the Hα line profile by the
  Interferometric Bidimensional Spectrometer (IBIS) and in the Hβ
  with the Rapid Oscillations in the Solar Atmosphere (ROSA) broadband
  imager are analyzed to obtain the intensity evolution. The analysis
  shows that Hα and Hβ intensity excesses in three identified flare
  footpoints are well correlated in time. In the stronger footpoints,
  the typical value of the the Hα/Hβ intensity ratio observed is ∼
  0.4 - 0.5, in broad agreement with values obtained from a RADYN non-LTE
  simulation driven by an electron beam with parameters constrained by
  observations. The weaker footpoint has a larger Hα/Hβ ratio, again
  consistent with a RADYN simulation but with a smaller energy flux.

---------------------------------------------------------
Title: Dynamical and Chemical Tracers in Jupiter's Troposphere and
    Stratosphere from the Earth-Based Infrared Juno Support Campaign
Authors: Melin, H.; Fletcher, L. N.; Donnelly, P. T.; Greathouse,
   T.; Lacy, J.; Orton, G.; Giles, R.; Sinclair, J. A.; Irwin, P. G.
2017AGUFM.P31C2841M    Altcode:
  The three-dimensional distribution of temperatures, chemical tracers
  and aerosol opacity in Jupiter's troposphere and stratosphere
  can be characterised by inverting spectra and images taken the
  mid-infrared. We present NASA IRTF TEXES, Gemini TEXES and VLT VISIR
  5-25 µm spectral maps of Jupiter obtained in the run-up, and during
  the Juno mission at Jupiter, providing crucial observations in the
  mid-infrared, a wavelength region not covered by Juno's suite of
  instruments. The NASA IRTF TEXES observations form a long baseline of
  spectroscopic maps between 2012 and 2017, providing temporal context
  for Juno's observations. Using this dataset we investigate the zonal
  abundance distribution of acetylene and ethane, and how these change
  over time. Using the methane channel, we can retrieve the vertical
  temperature profile between 1 and 10 mbar and track a full cycle of
  Jupiter's equatorial stratospheric oscillation. We confirm that the
  acetylene abundance decreases towards the pole, whilst ethane increases
  towards the pole. We find that the data supports the hypothesis
  that acetylene is asymmetric about the equator, and varies with time
  in response to short-lived dynamical changes. We suggest that this
  asymmetry, which changes over time, is driven by stratospheric wave
  activity. Conversely, ethane appears to be symmetric about the equator,
  and does not vary with time. The stark difference between acetylene
  and ethane is likely linked to the two species having very different
  chemical life-times and vertical abundance gradients. Gemini TEXES
  spectral mapping in March 2017 reveals - in addition to temperatures -
  the spatial distribution of ammonia, phosphine and upper tropospheric
  aerosols at high spatial resolution. We confirm the equatorial NH3
  enhancement observed by Juno, and investigate the distribution of
  these dynamical tracers in the vicinity of NEB hotspots, an SEB plume
  outbreak, and the Great Red Spot.

---------------------------------------------------------
Title: Ammonia in Jupiter's troposphere: a comparison of ground-based
    5-μm high-resolution spectroscopy and Juno MWR observations
Authors: Giles, R.; Orton, G.; Fletcher, L. N.; Irwin, P. G.; Sinclair,
   J. A.
2017AGUFM.P31C2812G    Altcode:
  Latitudinally-resolved 5-micron observations of Jupiter from the
  CRIRES instrument at the Very Large Telescope are used to measure
  the spatial variability in Jupiter's tropospheric ammonia (NH3)
  abundance and these results are compared to the results from Juno's
  Microwave Radiometer (MWR). The 5-micron spectral region is an
  atmospheric window, allowing us to probe down to Jupiter's middle
  troposphere. The high-resolution 2012 CRIRES observations include
  several spectrally-resolved NH3 absorption features; these features
  probe slightly different pressure levels, allowing the NH3 vertical
  profile at 1-4 bar to be constrained. We find that in regions of low
  cloud opacity, the NH3 abundance must decrease with altitude within
  this pressure range. The CRIRES observations do not provide evidence for
  any significant belt-zone variability in NH3, as any difference in the
  spectral shape can be accounted for by the large differences in cloud
  opacity between the cloudy zones and the cloud-free belts. However,
  we do find evidence for a strong localised enhancement in NH3 on the
  southern edge of the North Equatorial Belt (4-6°N). These results
  can be directly compared with observations from the Juno mission's MWR
  experiment. Li et al. (2017, doi 10.1002/2017GL073159) have used MWR
  data to retrieve NH3 abundances at pressure levels of 1-100 bar. In
  bright, cloud-free regions of the planet, the two datasets are broadly
  consistent, including the asymmetrical enhancement on the southern
  edge of the NEB. However, in the cool, cloudy Equatorial Zone, the MWR
  retrieved abundances are significantly higher than those from CRIRES and
  forward modeling shows that the MWR vertical distributions are unable
  to fit the CRIRES data. We will investigate possible explanations
  for this discrepancy, including the role of tropospheric clouds and
  temperature variations.

---------------------------------------------------------
Title: Non-thermal Power-Law Distributions in Solar and Space Plasmas
Authors: Oka, M.; Battaglia, M.; Birn, J.; Chaston, C. C.; Effenberger,
   F.; Eriksson, E.; Fletcher, L.; Hatch, S.; Imada, S.; Khotyaintsev,
   Y. V.; Kuhar, M.; Livadiotis, G.; Miyoshi, Y.; Retino, A.
2017AGUFMSH51C2518O    Altcode:
  Particles are accelerated to very high, non-thermal energies in solar
  and space plasma environments. While energy spectra of accelerated
  particles often exhibit a power-law and are characterized by the
  power-law index δ, it remains unclear how particles are accelerated
  to high energies and how δ is determined. Here, we review previous
  observations of the power-law index δ in a variety of different plasma
  environments with a particular focus on sub-relativistic electrons. It
  appears that in regions more closely related to magnetic reconnection
  (such as the "above-the-looptop" solar hard X-ray source and the plasma
  sheet in Earth's magnetotail), the spectra are typically soft (δ&gt;
  4). This is in contrast to the typically hard spectra (δ&lt; 4)
  that are observed in coincidence with shocks. The difference implies
  that shocks are more efficient in producing a larger fraction of
  non-thermal electron energies than magnetic reconnection. A caveat
  is that during active times in Earth's magnetotail, δ values seem
  spatially uniform in the plasma sheet, while power-law distributions
  still exist even in quiet times. The role of magnetotail reconnection
  in the electron power-law formation could therefore be confounded
  with these background conditions. Because different regions have been
  studied with different instrumentations and methodologies, we point
  out a need for more systematic and coordinated studies of power-law
  distributions for a better understanding of possible scaling laws in
  particle acceleration as well as their universality.

---------------------------------------------------------
Title: High spatial and spectral resolution measurements of Jupiter's
    auroral regions using Gemini-North-TEXES
Authors: Sinclair, J. A.; Orton, G. S.; Greathouse, T. K.; Lacy, J.;
   Giles, R.; Fletcher, L. N.; Vogt, M.; Irwin, P. G.
2017AGUFM.P24A..08S    Altcode:
  Jupiter exhibits auroral emission at a multitude of wavelengths. Auroral
  emission at X-ray, ultraviolet and near-infrared wavelengths demonstrate
  the precipitation of ion and electrons in Jupiter's upper atmosphere, at
  altitudes exceeding 250 km above the 1-bar level. Enhanced mid-infrared
  emission of CH4, C2H2, C2H4 and further hydrocarbons is also observed
  coincident with Jupiter's auroral regions. Retrieval analyses
  of infrared spectra from IRTF-TEXES (Texas Echelon Cross Echelle
  Spectrograph on NASA's Infrared Telescope Facility) indicate strong
  heating at the 1-mbar level and evidence of ion-neutral chemistry,
  which enriches the abundances of unsaturated hydrocarbons (Sinclair
  et al., 2017b, doi:10.1002/2017GL073529, Sinclair et al., 2017c (under
  review)). The extent to which these phenomena in the stratosphere are
  correlated and coupled physically with the shorter-wavelength auroral
  emission originating from higher altitudes has been a challenge due
  to the limited spatial resolution available on the IRTF. Smaller-scale
  features observed in the near-infrared and ultraviolet emission, such as
  the main `oval', transient `swirls' and dusk-active regions within the
  main oval (e.g. Stallard et al., 2014, doi:10.1016/j/Icarus.2015.12.044,
  Nichols et al., 2017, doi: 10.1002/2017GL073029) are potentially being
  blurred in the mid-infrared by the diffraction-limited resolution
  (0.7") of IRTF's 3-metre primary aperture. However, on March 17-19th
  2017, we obtained spectral measurements of H2 S(1), CH4, C2H2, C2H4 and
  C2H6 emission of Jupiter's high latitudes using TEXES on Gemini-North,
  which has a 8-metre primary aperture. This rare opportunity combines
  the superior spectral resolving power of TEXES and the high spatial
  resolution provided by Gemini-North's 8-metre aperture. We will
  perform a retrieval analyses to determine the 3D distributions of
  temperature, C2H2, C2H4 and C2H6. The morphology will be compared
  with near-contemporaneous measurements of H3+ emission from IRTF-SpeX
  and Juno-JIRAM/UVS to assess the extent of coupling between the
  stratosphere and ionosphere. In addition, a magnetospheric mapping tool
  (Vogt et al. 2011, doi:10.1029/2010JA016148) will be used to determine
  whether small-scale features are likely linked to the solar wind or
  the magnetosphere.

---------------------------------------------------------
Title: Characterization of Jupiter's Atmosphere from Observation of
    Thermal Emission by Juno and Ground-Based Supporting Observations
Authors: Orton, G. S.; Momary, T.; Tabataba-Vakili, F.; Janssen, M. A.;
   Hansen, C. J.; Bolton, S. J.; Li, C.; Adriani, A.; Mura, A.; Grassi,
   D.; Fletcher, L. N.; Brown, S. T.; Fujiyoshi, T.; Greathouse, T. K.;
   Kasaba, Y.; Sato, T. M.; Stephens, A.; Donnelly, P.; Eichstädt, G.;
   Rogers, J.
2017AGUFM.P23E..02O    Altcode:
  Ground-breaking measurements of thermal emission at very long
  wavelengths have been made by the Juno mission's Microwave Radiometer
  (MWR). We examine the relationship between these and other thermal
  emission measurements by the Jupiter Infrared Auroral Mapper (JIRAM)
  at 5 µm and ground-based supporting observations in the thermal
  infrared that cover the 5-25 µm range. The relevant ground-based
  observations of thermal emission are constituted from imaging and
  scanning spectroscopy obtained at the NASA Infrared Telescope Facility
  (IRTF), the Gemini North Telescope, the Subaru Telescope and the Very
  Large Telescope. A comparison of these results clarifies the physical
  properties responsible for the observed emissions, i.e. variability of
  the temperature field, the cloud field or the distribution of gaseous
  ammonia. Cross-references to the visible cloud field from Juno's
  JunoCam experiment and Earth-based images are also useful. This work
  continues an initial comparison by Orton et al. (2017, GRL 44, doi:
  10.1002/2017GL073019) between MWR and JIRAM results, together with
  ancillary 5-µm IRTF imaging and with JunoCam and ground-based visible
  imaging. These showed a general agreement between MWR and JIRAM results
  for the 5-bar NH3 abundance in specific regions of low cloud opacity
  but only a partial correlation between MWR and 5-µm radiances emerging
  from the 0.5-5 bar levels of the atmosphere in general. Similar to the
  latter, there appears to be an inconsistent correlation between MWR
  channels sensitive to 0.5-10 bars and shorter-wavelength radiances
  in the "tails" of 5-µm hot spots , which may be the result of the
  greater sensitivity of the latter to particulate opacity that could
  depend on the evolution history of the particular features sampled. Of
  great importance is the interpretation of MWR radiances in terms
  of the variability of temperature vs. NH3 abundances in the 0.5-5
  bar pressure range. This is particularly important to understand
  MWR results in Jupiter's Great Red Spot. It may also be important
  to understand apparent differences between MWR and high-resolution
  spectroscopic observations around Jupiter's equator.

---------------------------------------------------------
Title: D/H Ratios on Saturn and Jupiter from Cassini CIRS
Authors: Pierel, J. D. R.; Nixon, C. A.; Lellouch, E.; Fletcher, L. N.;
   Bjoraker, G. L.; Achterberg, R. K.; Bézard, B.; Hesman, B. E.; Irwin,
   P. G. J.; Flasar, F. M.
2017AJ....154..178P    Altcode:
  We present new measurements of the deuterium abundance on Jupiter
  and Saturn, showing evidence that Saturn's atmosphere contains less
  deuterium than Jupiter's. We analyzed far-infrared spectra from the
  Cassini Composite Infrared Spectrometer to measure the abundance of
  HD on both giant planets. Our estimate of the Jovian D/H = (2.95 ±
  0.55) × 10<SUP>-5</SUP> is in agreement with previous measurements
  by ISO/SWS: (2.25 ± 0.35) × 10<SUP>-5</SUP>, and the Galileo probe:
  (2.6 ± 0.7) × 10<SUP>-5</SUP>. In contrast, our estimate of the
  Saturn value of (2.10 ± 0.13) × 10<SUP>-5</SUP> is somewhat lower
  than on Jupiter (by a factor of 0.71<SUB>-0.15</SUB><SUP>+0.22</SUP>),
  contrary to model predictions of a higher ratio: Saturn/Jupiter =
  1.05-1.20. The Saturn D/H value is consistent with estimates for
  hydrogen in the protosolar nebula (2.1 ± 0.5) × 10<SUP>-5</SUP>,
  but its apparent divergence from the Jovian value suggests that our
  understanding of planetary formation and evolution is incomplete,
  which is in agreement with previous work.

---------------------------------------------------------
Title: Hα and Hβ Emission in a C3.3 Solar Flare: Comparison between
    Observations and Simulations
Authors: Capparelli, Vincenzo; Zuccarello, Francesca; Romano, Paolo;
   Simões, Paulo J. A.; Fletcher, Lyndsay; Kuridze, David; Mathioudakis,
   Mihalis; Keys, Peter H.; Cauzzi, Gianna; Carlsson, Mats
2017ApJ...850...36C    Altcode: 2017arXiv171004067C
  The hydrogen Balmer series is a basic radiative loss channel from
  the flaring solar chromosphere. We report here on the analysis of an
  extremely rare set of simultaneous observations of a solar flare in the
  {{H}}α and {{H}}β lines, at high spatial and temporal resolutions,
  that were acquired at the Dunn Solar Telescope. Images of the C3.3 flare
  (SOL2014-04-22T15:22) made at various wavelengths along the {{H}}α line
  profile by the Interferometric Bidimensional Spectrometer (IBIS) and in
  the {{H}}β with the Rapid Oscillations in the Solar Atmosphere (ROSA)
  broadband imager are analyzed to obtain the intensity evolution. The
  {{H}}α and {{H}}β intensity excesses in three identified flare
  footpoints are well-correlated in time. We examine the ratio of {{H}}α
  to {{H}}β flare excess, which was proposed by previous authors as
  a possible diagnostic of the level of electron-beam energy input. In
  the stronger footpoints, the typical value of the the {{H}}α /H β
  intensity ratio observed is ∼0.4-0.5, in broad agreement with values
  obtained from a RADYN non-LTE simulation driven by an electron beam
  with parameters constrained (as far as possible) by observation. The
  weaker footpoint has a larger {{H}}α /H β ratio, again consistent
  with a RADYN simulation, but with a smaller energy flux. The {{H}}α
  line profiles observed have a less prominent central reversal than is
  predicted by the RADYN results, but can be brought into agreement if
  the {{H}}α -emitting material has a filling factor of around 0.2-0.3.

---------------------------------------------------------
Title: Can Substorm Particle Acceleration Be Applied to Solar Flares?
Authors: Birn, J.; Battaglia, M.; Fletcher, L.; Hesse, M.; Neukirch, T.
2017ApJ...848..116B    Altcode:
  Using test particle studies in the electromagnetic fields of
  three-dimensional magnetohydrodynamic (MHD) simulations of magnetic
  reconnection, we study the energization of charged particles in the
  context of the standard two-ribbon flare picture in analogy to the
  standard magnetospheric substorm paradigm. In particular, we investigate
  the effects of the collapsing field (“collapsing magnetic trap”)
  below a reconnection site, which has been demonstrated to be the major
  acceleration mechanism that causes energetic particle acceleration and
  injections observed in Earth’s magnetotail associated with substorms
  and other impulsive events. We contrast an initially force-free,
  high-shear field (low beta) with low and moderate shear, finite-pressure
  (high-beta) arcade structures, where beta represents the ratio between
  gas (plasma) and magnetic pressure. We demonstrate that the energization
  affects large numbers of particles, but the acceleration is modest in
  the presence of a significant shear field. Without incorporating loss
  mechanisms, the effect on particles at different energies is similar,
  akin to adiabatic heating, and thus is not a likely mechanism to
  generate a power-law tail onto a (heated or not heated) Maxwellian
  velocity distribution.

---------------------------------------------------------
Title: Comparing UV/EUV line parameters and magnetic field in a
    quiescent prominence with tornadoes
Authors: Levens, P. J.; Labrosse, N.; Schmieder, B.; López Ariste,
   A.; Fletcher, L.
2017A&A...607A..16L    Altcode: 2017arXiv170804606L
  Context. Understanding the relationship between plasma and the
  magnetic field is important for describing and explaining the
  observed dynamics of solar prominences. <BR /> Aims: We determine
  if a close relationship can be found between plasma and magnetic
  field parameters, measured at high resolution in a well-observed
  prominence. <BR /> Methods: A prominence observed on 15 July 2014 by
  the Interface Region Imaging Spectrograph (IRIS), Hinode, the Solar
  Dynamics Observatory (SDO), and the Télescope Héliographique pour
  l'Étude du Magnétisme et des Instabilités Solaires (THEMIS) is
  selected. We perform a robust co-alignment of data sets using a 2D
  cross-correlation technique. Magnetic field parameters are derived
  from spectropolarimetric measurements of the He I D<SUB>3</SUB> line
  from THEMIS. Line ratios and line-of-sight velocities from the Mg II h
  and k lines observed by IRIS are compared with magnetic field strength,
  inclination, and azimuth. Electron densities are calculated using Fe xii
  line ratios from the Hinode Extreme-ultraviolet Imaging Spectrometer,
  which are compared to THEMIS and IRIS data. <BR /> Results: We find
  Mg II k/h ratios of around 1.4 everywhere, similar to values found
  previously in prominences. Also, the magnetic field is strongest (
  30 G) and predominantly horizontal in the tornado-like legs of the
  prominence. The k<SUB>3</SUB> Doppler shift is found to be between
  ±10 km s<SUP>-1</SUP> everywhere. Electron densities at a temperature
  of 1.5 × 10<SUP>6</SUP> K are found to be around 10<SUP>9</SUP>
  cm<SUP>-3</SUP>. No significant correlations are found between the
  magnetic field parameters and any of the other plasma parameters
  inferred from spectroscopy, which may be explained by the large
  differences in the temperatures of the lines used in this study. <BR />
  Conclusions: This is the first time that a detailed statistical study of
  plasma and magnetic field parameters has been performed at high spatial
  resolution in a prominence. Our results provide important constraints
  on future models of the plasma and magnetic field in these structures.

---------------------------------------------------------
Title: Detection of Three-minute Oscillations in Full-disk Lyα
    Emission during a Solar Flare
Authors: Milligan, Ryan O.; Fleck, Bernhard; Ireland, Jack; Fletcher,
   Lyndsay; Dennis, Brian R.
2017ApJ...848L...8M    Altcode: 2017arXiv170909037M
  In this Letter we report the detection of chromospheric 3-minute
  oscillations in disk-integrated EUV irradiance observations during a
  solar flare. A wavelet analysis of detrended Lyα (from GOES/EUVS) and
  Lyman continuum (from Solar Dynamics Observatory (SDO)/EVE) emission
  from the 2011 February 15 X-class flare (SOL2011-02-15T01:56) revealed
  a ∼3 minute period present during the flare’s main phase. The
  formation temperature of this emission locates this radiation at the
  flare’s chromospheric footpoints, and similar behavior is found
  in the SDO/Atmospheric Imaging Assembly 1600 and 1700 Å channels,
  which are dominated by chromospheric continuum. The implication is
  that the chromosphere responds dynamically at its acoustic cutoff
  frequency to an impulsive injection of energy. Since the 3-minute
  period was not found at hard X-ray (HXR) energies (50-100 keV) in
  Reuven Ramaty High Energy Solar Spectroscopic Imager data we can
  state that this 3-minute oscillation does not depend on the rate of
  energization of non-thermal electrons. However, a second period of 120
  s found in both HXR and chromospheric lightcurves is consistent with
  episodic electron energization on 2-minute timescales. Our finding on
  the 3-minute oscillation suggests that chromospheric mechanical energy
  should be included in the flare energy budget, and the fluctuations in
  the Lyα line may influence the composition and dynamics of planetary
  atmospheres during periods of high activity.

---------------------------------------------------------
Title: Water and Volatiles in the Outer Solar System
Authors: Grasset, O.; Castillo-Rogez, J.; Guillot, T.; Fletcher,
   L. N.; Tosi, F.
2017SSRv..212..835G    Altcode: 2017SSRv..tmp..135G
  Space exploration and ground-based observations have provided
  outstanding evidence of the diversity and the complexity of the outer
  solar system. This work presents our current understanding of the
  nature and distribution of water and water-rich materials from the
  water snow line to the Kuiper Belt. This synthesis is timely, since
  a thorough exploration of at least one object in each region of the
  outer solar system has now been achieved. Next steps, starting with
  the Juno mission now in orbit around Jupiter, will be more focused on
  understanding the processes at work than on describing the general
  characteristics of each giant planet systems. <P />This review is
  organized in three parts. First, the nature and the distribution of
  water and volatiles in giant and intermediary planets are described
  from their inner core to their outer envelopes. A special focus is
  given to Jupiter and Saturn, which are much better understood than the
  two ice giants (Uranus and Neptune) thanks to the Galileo and Cassini
  missions. Second, the icy moons will be discussed. Space missions and
  ground-based observations have revealed the variety of icy surfaces
  in the outer system. While Europa, Enceladus, and maybe Titan present
  past or even active tectonic and volcanic activities, many other moons
  have been dead worlds for more than 3 billion years. Ice compositions
  found at these bodies are also complex and it is now commonly admitted
  that icy surfaces are never composed of pure ices. A detailed review
  of the distribution of non-ice materials on the surfaces and in the
  tenuous atmospheres of the moons is proposed, followed by a more focused
  discussion on the nature and the characteristics of the liquid layers
  trapped below the cold icy crusts that have been suggested in the icy
  Galilean moons, and in Enceladus, Dione, and Titan at Saturn. Finally,
  the recent observations collected by Dawn at Ceres and New Horizons
  at Pluto, as well as the state of knowledge of other transneptunian
  objects, are summarized, and complete this overview of the nature and
  distribution of ice-rich material in the outer solar system.

---------------------------------------------------------
Title: Seismology of contracting and expanding coronal loops using
    damping of kink oscillations by mode coupling
Authors: Pascoe, D. J.; Russell, A. J. B.; Anfinogentov, S. A.;
   Simões, P. J. A.; Goddard, C. R.; Nakariakov, V. M.; Fletcher, L.
2017A&A...607A...8P    Altcode:
  <BR /> Aims: We extend recently developed seismological methods to
  analyse oscillating loops which feature a large initial shift in the
  equilibrium position and investigate additional observational signatures
  related to the loop environment and oscillation driver. <BR /> Methods:
  We model the motion of coronal loops as a kink oscillation damped by
  mode coupling, accounting for any change in loop length and the possible
  presence of parallel harmonics in addition to the fundamental mode. We
  apply our model to a loop which rapidly contracts due to a post-flare
  implosion (SOL2012-03-09) and a loop with a large lateral displacement
  (SOL2012-10-20). <BR /> Results: The seismological method is used to
  calculate plasma parameters of the oscillating loops including the
  transverse density profile, magnetic field strength, and phase mixing
  timescale. For SOL2012-03-09 the period of oscillation has a linear
  correlation with the contracting motion and suggests the kink speed
  remains constant during the oscillation. The implosion excitation
  mechanism is found to be associated with an absence of additional
  parallel harmonics. <BR /> Conclusions: The improved Bayesian
  analysis of the coronal loop motion allows for accurate seismology
  of plasma parameters, and the evolution of the period of oscillation
  compared with the background trend can be used to distinguish between
  loop motions in the plane of the loop and those perpendicular to
  it. The seismologically inferred kink speed and density contrast
  imply sub-Alfvénic (M<SUB>A</SUB> = 0.16 ± 0.03) propagation of the
  magnetic reconfiguration associated with the implosion, as opposed to
  triggering by a wave propagating at the Alfvén speed.

---------------------------------------------------------
Title: Observations of Reconnection Flows in a Flare on the Solar Disk
Authors: Wang, Juntao; Simões, P. J. A.; Jeffrey, N. L. S.; Fletcher,
   L.; Wright, P. J.; Hannah, I. G.
2017ApJ...847L...1W    Altcode: 2017arXiv170808706W
  Magnetic reconnection is a well-accepted part of the theory of solar
  eruptive events, though the evidence is still circumstantial. Intrinsic
  to the reconnection picture of a solar eruptive event, particularly
  in the standard model for two-ribbon flares (CSHKP model), are an
  advective flow of magnetized plasma into the reconnection region,
  expansion of field above the reconnection region as a flux rope
  erupts, retraction of heated post-reconnection loops, and downflows
  of cooling plasma along those loops. We report on a unique set of
  Solar Dynamics Observatory/Atmospheric Imaging Assembly imaging and
  Hinode/EUV Imaging Spectrometer spectroscopic observations of the
  disk flare SOL2016-03-23T03:54 in which all four flows are present
  simultaneously. This includes spectroscopic evidence for a plasma
  upflow in association with large-scale expanding closed inflow
  field. The reconnection inflows are symmetric, and consistent with
  fast reconnection, and the post-reconnection loops show a clear cooling
  and deceleration as they retract. Observations of coronal reconnection
  flows are still rare, and most events are observed at the solar limb,
  obscured by complex foregrounds, making their relationship to the
  flare ribbons, cusp field, and arcades formed in the lower atmosphere
  difficult to interpret. The disk location and favorable perspective
  of this event have removed these ambiguities giving a clear picture
  of the reconnection dynamics.

---------------------------------------------------------
Title: Identifying the source of colour and featural changes in
    Jupiter's atmosphere from MUSE/VLT
Authors: Braude, A. S.; Irwin, P. G. J.; Orton, G. S.; Fletcher, L. N.
2017EPSC...11..806B    Altcode:
  We use ground-based observations from the MUSE/VLT instrument to
  characterise changes in cloud structure and colour in Jupiter's
  atmosphere between 2014-2017, and providing global context
  to observations of Jupiter from the Juno spacecraft. We witness
  significant changes in Jupiter's banded structure in the northern
  hemisphere in 2017, and we also confirm that the colour in Jupiter's
  red regions can be well-modelled using a red substance produced through
  the photochemical reaction of ammonia with acetylene. This implies a
  high-altitude source of colour in Jupiter's atmosphere.

---------------------------------------------------------
Title: Exploration of Jupiter's atmosphere and magnetosphere with
    the European Jupiter Icy Moons Explorer (JUICE)
Authors: Cavalié, T.; Fletcher, L.; Krupp, N.; Masters, A.;
   Witasse, O.
2017EPSC...11..420C    Altcode:
  JUICE - JUpiter ICy moons Explorer - is the first large mission in ESA's
  Cosmic Vision 2015-2025 programme. The mission was selected in May 2012
  and adopted in November 2014. The implementation phase started in July
  2015. Planned for launch in June 2022 and arrival at Jupiter in October
  2029, it will spend at least three years making detailed observations
  of Jupiter and three of its largest moons, Ganymede, Callisto and
  Europa. JUICE will then orbit Ganymede for almost a year. JUICE
  will perform a varied and extensive orbital tour with access to high
  latitudes to provide a comprehensive study of the unique environmental
  conditions at Jupiter's poles. The overarching theme for JUICE is:
  The emergence of habitable worlds around gas giants. JUICE will also
  perform a multidisciplinary investigation of the Jupiter as an archetype
  for gas giants. In this paper, we will present the science objectives
  and key measurements performed by the instrument suite, relevant to
  the study of the atmosphere and magnetosphere of Jupiter. We will also
  present the first steps of the science implementation, as performed
  by the ESA Working Groups and Science Working Team.

---------------------------------------------------------
Title: Detection of Compact Baroclinic Waves in Jupiter's Deep Clouds
    at 5-microns from the VLT
Authors: Fletcher, L. N.; Donnelly, P.; Melin, H.; Orton, G. S.;
   Greathouse, T. K.; Sinclair, J. A.; Giles, R. S.; Simon, A. A.;
   de Pater, I.; Wong, M.
2017EPSC...11..454F    Altcode:
  A campaign of Earth-based supporting observations is providing spatial,
  temporal and spectral context to the close-in orbital exploration of
  Jupiter by the Juno mission. This campaign, utilising 8-m observatories
  on Earth, is providing some of the highest resolution mid-infrared
  observations of Jupiter ever obtained, allowing us to probe the scale
  of compact wave patterns for the first time. We report the detection
  of a compact (1-degree longitude) wave in the deep clouds of the North
  Equatorial Belt at 5-microns, coincident with a structure observed by
  Hubble in reflected sunlight at higher altitudes.

---------------------------------------------------------
Title: The Hera Saturn Entry Probe Mission: a Proposal in Response
    to the ESA M5 Call
Authors: Mousis, O.; Atkinson, D.; Amato, M.; Aslam, S.; Atreya,
   S.; Blanc, M.; Bolton, S.; Brugger, B.; Calcutt, S.; Cavalié, T.;
   Charnoz, S.; Coustenis, A.; Deleuil, M.; Dobrijevic, M.; Ferri, F.;
   Fletcher, L.; Gautier, D.; Guillot, T.; Hartogh, P.; Holland, A.
2017EPSC...11..305M    Altcode:
  The Hera Saturn entry probe mission is proposed as an ESA M-class
  mission to be piggybacked on a NASA spacecraft sent to or past the
  Saturn system. Hera consists of an atmospheric probe built by ESA and
  released into the atmosphere of Saturn by its NASA companion Saturn
  Carrier-Relay spacecraft. Hera will perform in situ measurements of the
  chemical and isotopic composition as well as the structure and dynamics
  of Saturn's atmosphere using a single probe, with the goal of improving
  our understanding of the origin, formation, and evolution of Saturn,
  the giant planets and their satellite systems, with extrapolation to
  extrasolar planets. Hera will probe well into and possibly beneath the
  cloud-forming region of the troposphere, below the region accessible
  to remote sensing, to locations where certain cosmogenically abundant
  species are expected to be well mixed.

---------------------------------------------------------
Title: Formation of the thermal infrared continuum in solar flares
Authors: Simões, Paulo J. A.; Kerr, Graham S.; Fletcher, Lyndsay;
   Hudson, Hugh S.; Giménez de Castro, C. Guillermo; Penn, Matt
2017A&A...605A.125S    Altcode: 2017arXiv170609867S
  <BR /> Aims: Observations of the Sun with the Atacama Large Millimeter
  Array have now started, and the thermal infrared will regularly be
  accessible from the NSF's Daniel K. Inouye Solar Telescope. Motivated by
  the prospect of these new data, and by recent flare observations in the
  mid infrared, we set out here to model and understand the source of the
  infrared continuum in flares, and to explore its diagnostic capability
  for the physical conditions in the flare atmosphere. <BR /> Methods:
  We use the one-dimensional (1D) radiation hydrodynamics code RADYN
  to calculate mid-infrared continuum emission from model atmospheres
  undergoing sudden deposition of energy by non-thermal electrons. <BR
  /> Results: We identify and characterise the main continuum thermal
  emission processes relevant to flare intensity enhancement in the
  mid- to far-infrared (2-200 μm) spectral range as free-free emission
  on neutrals and ions. We find that the infrared intensity evolution
  tracks the energy input to within a second, albeit with a lingering
  intensity enhancement, and provides a very direct indication of the
  evolution of the atmospheric ionisation. The prediction of highly
  impulsive emission means that, on these timescales, the atmospheric
  hydrodynamics need not be considered in analysing the mid-IR signatures.

---------------------------------------------------------
Title: Characterising Jupiter's Temperatures, Aerosols and Ammonia
    via VLT/VISIR Spatial Mapping 2016-17
Authors: Donnelly, P. T.; Fletcher, L. N.; Orton, G. S.; Melin, H.
2017EPSC...11..581D    Altcode:
  The VISIR mid-IR imager (5-25 µm) on the Very Large Telescope (VLT)
  has been providing infrared spatial and temporal support for NASA's
  Juno spacecraft, constraining atmospheric thermal conditions in the
  upper troposphere (100-700 mbar) and stratosphere (1-10 mbar). Our
  pre-Juno-arrival dataset (January-August 2016) demonstrated that
  Jupiter's North Equatorial Belt (NEB) began a northward expansion in
  late 2015, consistent with the 3-5 year cycle of NEB activity. VISIR
  detected two new thermal waves during this period; an upper tropospheric
  wave in the mid-NEB and a stratospheric wave centred on the eastward
  jet at 23.9°N. The latter was quasi-stationary and both waves are
  morphologically similar to those observed during the 2000 expansion
  event by Cassini. We now extend this analysis to coincide with Juno's
  perijove encounters, once every 53.5 days. We report (i) the continued
  existence of the mid-NEB wave; (ii) evolution of Jupiter's North
  Temperate Belt (NTB) following the October 2016 outbreak; and (iii)
  complex thermal variability associated with a mid-SEB outbreak during
  2017. We discuss zonally-averaged temperatures, aerosols and ammonia
  distributions derived from VLT data (taking centre-to-limb variations
  into account), comparing the upper-tropospheric aerosols and ammonia
  to the findings of Juno's near-infrared and microwave observations.

---------------------------------------------------------
Title: The New Frontiers Saturn PRobe Interior and aTmosphere Explorer
    (SPRITE) Mission Proposal
Authors: Atkinson, D. H.; Simon, A. A.; Banfield, D.; Atreya, S.;
   Blacksberg, J.; Brinckerhoff, W.; Colaprete, A.; Coustenis, A.;
   Fletcher, L.; Guillot, T.; Hofstadter, M.; Lunine, J.; Mahaffy, P.;
   Marley, M.; Mousis, O.; Spilker, T.; Trainer, M.; Webster, C.
2017EPSC...11..356A    Altcode:
  SPRITE is a Saturn Probe mission proposal submitted to NASA under the
  New Frontiers 4 program.

---------------------------------------------------------
Title: Scientific rationale and concepts for in situ probe exploration
    of Uranus and Neptune
Authors: Mousis, O.; Atkinson, D.; Amato, M.; Aslam, S.; Atreya,
   S.; Blanc, M.; Brugger, B.; Calcutt, S.; Cavalié, T.; Charnoz, S.;
   Coustenis, A.; Deleuil, M.; Dobrijevic, M.; Encrenaz, T.; Ferri, F.;
   Fletcher, L.; Guillot, T.; Hartogh, P.; Hofstadter, M.; Hueso, R.
2017EPSC...11..299M    Altcode:
  Uranus and Neptune, referred to as ice giants, are fundamentally
  different from the better-known gas giants (Jupiter and
  Saturn). Exploration of an ice giant system is a high-priority science
  objective, as these systems (including the magnetosphere, satellites,
  rings, atmosphere, and interior) challenge our understanding of
  planetary formation and evolution. The importance of the ice giants is
  reflected in NASA's 2011 Decadal Survey, comments from ESA's SSC in
  response to L2/L3 mission proposals and results of the 2017 NASA/ESA
  Ice Giants study. A crucial part of exploration of the ice giants is
  in situ sampling of the atmosphere via an atmospheric probe. A probe
  would bring insights in two broad themes: the formation history of our
  Solar System and the processes at play in planetary atmospheres. Here
  we summarize the science driver for in situ measurements at these two
  planets and discuss possible mission concepts that would be consistent
  with the constraints of ESA M-class missions.

---------------------------------------------------------
Title: Saturn at Northern Summer Solstice: Thermal Structure during
    the Finale of the Cassini Mission
Authors: Fletcher, L. N.; Guelet, S.; Orton, G. S.; Sinclair, J. A.;
   Fouchet, T.; Irwin, P.; Li, L.; Flasar, F. M.
2017EPSC...11..450F    Altcode:
  With the culmination of 13 years of orbital exploration of Saturn by the
  Cassini spacecraft, we now have the most comprehensive characterisation
  of a seasonal giant planet ever obtained. The longevity of Cassini
  has meant that we can explore atmospheric processes from solstice
  to solstice using infrared remote sensing, including: the formation
  and dissipation of stratospheric polar vortices; the evolution of
  Saturn's equatorial oscillation; and the aftermath of the 2010-11
  springtime storm.

---------------------------------------------------------
Title: Saturn's stratospheric equatorial oscillation and wave activity
    through the Cassini epoch
Authors: Guerlet, S.; Fouchet, T.; Spiga, A.; Hesman, B.; Gorius,
   N.; Fletcher, L.; Flasar, F. M.
2017EPSC...11..172G    Altcode:
  We study the evolution of Saturn's Quasi-Periodic Oscillation,
  a dynamical phenomenon observed in Saturn's stratosphere that has
  counterparts in Jupiter and the Earth stratospheres as well. Thermal
  infrared spectra acquired by Cassini/CIRS in limb viewing geometry
  in 2015 are used to derive 2-D latitude-pressure temperature and
  thermal wind maps in Saturn's stratosphere. These maps are compared
  to previous observations from 2005 and 2010 to characterize and
  study the evolution of the vertical structure of Saturn's equatorial
  oscillation. This phenomenon is thought to result from the interaction
  between upward-propagating waves and the mean zonal flow, but little
  is known on Saturn's stratospheric wave activity. CIRS nadir spectra
  are then used to map stratospheric temperatures with longitude and
  characterize planetary waves in the tropical region (20N-20S).

---------------------------------------------------------
Title: Saturn's Atmospheric Photochemistry: Haze Production in
    Ring-Shadowed Atmosphere and within the Hexagon
Authors: Edgington, S. G.; Atreya, S. K.; Wilson, E. H.; Baines,
   K. H.; West, R. A.; Bjoraker, G. L.; Fletcher, L. N.; Momary, T.
2017EPSC...11..386E    Altcode:
  This research explores the impact of seasonal changes within Saturn's
  atmosphere and the evolution of hazes within it.

---------------------------------------------------------
Title: The thermal infrared continuum in solar flares
Authors: Fletcher, Lyndsay; Simoes, Paulo; Kerr, Graham Stewart;
   Hudson, Hugh S.; Gimenez de Castro, C. Guillermo; Penn, Matthew J.
2017SPD....4810821F    Altcode:
  Observations of the Sun with the Atacama Large Millimeter Array have
  now started, and the thermal infrared will regularly be accessible
  from the NSF’s Daniel K. Inouye Solar Telescope. Motivated by the
  prospect of these new observations, and by recent flare detections in
  the mid infrared, we set out here to model and understand the source
  of the infrared continuum in flares, and to explore its diagnostic
  capability for the physical conditions in the flare atmosphere. We use
  the 1D radiation hydrodynamics code RADYN to calculate mid-infrared
  continuum emission from model atmospheres undergoing sudden deposition
  of energy by non-thermal electrons. We identify and characterise the
  main continuum thermal emission processes relevant to flare intensity
  enhancement in the mid- to far-infrared (2-200 micron) spectral range
  as free-free emission on neutrals and ions. We find that the infrared
  intensity evolution tracks the energy input to within a second,
  albeit with a lingering intensity enhancement, and provides a very
  direct indication of the evolution of the atmospheric ionization. The
  prediction of highly impulsive emission means that, on these timescales,
  the atmospheric hydrodynamics need not be considered in analysing the
  mid-IR signatures.

---------------------------------------------------------
Title: Jupiter's auroral-related stratospheric heating and chemistry
I: Analysis of Voyager-IRIS and Cassini-CIRS spectra
Authors: Sinclair, J. A.; Orton, G. S.; Greathouse, T. K.; Fletcher,
   L. N.; Moses, J. I.; Hue, V.; Irwin, P. G. J.
2017Icar..292..182S    Altcode:
  Auroral processes are evident in Jupiter's polar atmosphere over
  a large range in wavelength (X-ray to radio). In particular,
  previous observations in the mid-infrared (5-15 μm) have shown
  enhanced emission from CH<SUB>4</SUB>, C<SUB>2</SUB>H<SUB>2</SUB>
  and C<SUB>2</SUB>H<SUB>4</SUB> and further stratospheric hydrocarbon
  species in spatial regions coincident with auroral processes observed at
  other wavelengths. These regions, described as auroral-related hotspots,
  observed at approximately 160°W to 200°W (System III) at high-northern
  latitudes and 330°W to 80°W at high-southern latitudes, indicate
  that auroral processes modify the thermal structure and composition
  of the neutral atmosphere. However, previous studies have struggled to
  differentiate whether the aforementioned enhanced emission is a result
  of either temperature changes and/or changes in the concentration of
  the emitting species. We attempt to address this degeneracy in this
  work by performing a retrieval analysis of Voyager 1-IRIS spectra
  (acquired in 1979) and Cassini-CIRS spectra (acquired in 2000/2001) of
  Jupiter. Retrievals of the vertical temperature profile in Cassini-CIRS
  spectra covering the auroral-related hotspots indicate the presence
  of two discrete vertical regions of heating at the 1-mbar level and
  at pressures of 10-μbar and lower. For example, in Cassini-CIRS
  2.5 cm-<SUP>1</SUP> 'MIRMAP' spectra at 70°N (planetographic)
  180°W (centred on the auroral oval), we find temperatures at the
  1-mbar level and 10-μbar levels are enhanced by 15.3 ± 5.2 K and
  29.6 ± 15.0 K respectively, in comparison to results at 70°N,
  60°W in the same dataset. High temperatures at 10 μbar and lower
  pressures were considered indicative of joule heating, ion and/or
  electron precipitation, ion-drag and energy released form exothermic
  ion-chemistry. However, we conclude that the heating at the 1-mbar
  level is the result of either a layer of aurorally-produced haze
  particles, which are heated by incident sunlight and/or adiabatic
  heating by downwelling within the auroral hot-spot region. The
  former mechanism would be consistent with the vertical profiles of
  polycyclic aromatic hydrocarbons (PAHs) and haze particles predicted
  in auroral-chemistry models (Wong et al., 2000; 2003). Retrievals of
  C<SUB>2</SUB>H<SUB>2</SUB> and C<SUB>2</SUB>H<SUB>6</SUB> were also
  performed and indicate C<SUB>2</SUB>H<SUB>2</SUB> is enriched but
  C<SUB>2</SUB>H<SUB>6</SUB> is depleted in auroral regions relative to
  quiescent regions. For example, using CIRS Δν∼ = 2.5 cm-<SUP>1</SUP>
  spectra, we determined that C<SUB>2</SUB>H<SUB>2</SUB> at 0.98 mbar
  increases by 175.3 ± 89.3 ppbv while C<SUB>2</SUB>H<SUB>6</SUB> at
  4.7 mbar decreases by 0.86 ± 0.59 ppmv in comparing results at 70°N,
  180°W and 70°N, 60°W. These results represent a mean of values
  retrieved from different initial assumptions and thus we believe they
  are robust. We believe these contrasts in C<SUB>2</SUB>H<SUB>2</SUB> and
  C<SUB>2</SUB>H<SUB>6</SUB> between auroral and quiescent regions can
  be explained by a coupling of auroral-driven chemistry and horizontal
  advection. Ion-neutral and electron recombination chemistry in
  the auroral region enriches all C<SUB>2</SUB> hydrocarbons but
  in particular, the unsaturated C<SUB>2</SUB>H<SUB>2</SUB> and
  C<SUB>2</SUB>H<SUB>4</SUB> hydrocarbons. Once advected outside of
  the auroral region, the unsaturated C<SUB>2</SUB> hydrocarbons are
  converted into C<SUB>2</SUB>H<SUB>6</SUB> by neutral photochemistry
  thereby enriching C<SUB>2</SUB>H<SUB>6</SUB> in quiescent regions,
  which gives the impression it is depleted inside the auroral region.

---------------------------------------------------------
Title: Modelling of the hydrogen Lyman lines during solar flares
Authors: Brown, Stephen Alistair; Fletcher, Lyndsay; Labrosse, Nicolas
2017SPD....4810303B    Altcode:
  The hydrogen Lyman series and continuum are both observed with high
  cadence and spectral resolution by the EVE instrument on NASA’s
  solar dynamics observatory. The Lyman lines, some of which will also be
  observed by the SPICE spectrometer on Solar Orbiter, can provide useful
  information about the dynamics of the solar chromosphere during a flare,
  where most of the event’s energy is deposited. In Brown et al (2016),
  we measured line shifts in the Lyman lines using the EVE instrument and
  calculated corresponding plasma flow speeds of around 30 kilometres
  per second. However, the observed signs of these shifts varied. We
  have also modelled Lyman line profiles output from the radiative
  hydrodynamic code RADYN (Carlsson &amp; Stein 1997, Allred et al 2015)
  and the radiative transfer code RH (Uitenbroek 2001) and present our
  initial findings. We show that the dynamics of the plasma are reflected
  in complex features in the true line profile, but that the detection of
  a line shift in a particular direction from EVE observations may not
  be indicative of the true plasma flow, particularly when these model
  profiles are passed through the EVE instrumental response. We present
  several cases of atmospheric responses for differing amounts of energy
  input, and outline interesting features in the Lyman line profiles which
  are thought to be linked to the response of the dynamic atmosphere.

---------------------------------------------------------
Title: Formation of diamonds in laser-compressed hydrocarbons at
    planetary interior conditions
Authors: Kraus, D.; Vorberger, J.; Pak, A.; Hartley, N. J.; Fletcher,
   L. B.; Frydrych, S.; Galtier, E.; Gamboa, E. J.; Gericke, D. O.;
   Glenzer, S. H.; Granados, E.; MacDonald, M. J.; MacKinnon, A. J.;
   McBride, E. E.; Nam, I.; Neumayer, P.; Roth, M.; Saunders, A. M.;
   Schuster, A. K.; Sun, P.; van Driel, T.; Döppner, T.; Falcone, R. W.
2017NatAs...1..606K    Altcode:
  The effects of hydrocarbon reactions and diamond precipitation on
  the internal structure and evolution of icy giant planets such
  as Neptune and Uranus have been discussed for more than three
  decades<SUP>1</SUP>. Inside these celestial bodies, simple
  hydrocarbons such as methane, which are highly abundant in
  the atmospheres<SUP>2</SUP>, are believed to undergo structural
  transitions<SUP>3,4</SUP> that release hydrogen from deeper layers
  and may lead to compact stratified cores<SUP>5-7</SUP>. Indeed,
  from the surface towards the core, the isentropes of Uranus and
  Neptune intersect a temperature-pressure regime in which methane
  first transforms into a mixture of hydrocarbon polymers<SUP>8</SUP>,
  whereas, in deeper layers, a phase separation into diamond and
  hydrogen may be possible. Here we show experimental evidence for
  this phase separation process obtained by in situ X-ray diffraction
  from polystyrene (C<SUB>8</SUB>H<SUB>8</SUB>)<SUB>n</SUB> samples
  dynamically compressed to conditions around 150 GPa and 5,000 K;
  these conditions resemble the environment around 10,000 km below the
  surfaces of Neptune and Uranus<SUP>9</SUP>. Our findings demonstrate
  the necessity of high pressures for initiating carbon-hydrogen
  separation<SUP>3</SUP> and imply that diamond precipitation may require
  pressures about ten times as high as previously indicated by static
  compression experiments<SUP>4,8,10</SUP>. Our results will inform
  mass-radius relationships of carbon-bearing exoplanets<SUP>11</SUP>,
  provide constraints for their internal layer structure and improve
  evolutionary models of Uranus and Neptune, in which carbon-hydrogen
  separation could influence the convective heat transport<SUP>7</SUP>.

---------------------------------------------------------
Title: Jupiter's North Equatorial Belt expansion and thermal wave
    activity ahead of Juno's arrival
Authors: Fletcher, L. N.; Orton, G. S.; Sinclair, J. A.; Donnelly, P.;
   Melin, H.; Rogers, J. H.; Greathouse, T. K.; Kasaba, Y.; Fujiyoshi,
   T.; Sato, T. M.; Fernandes, J.; Irwin, P. G. J.; Giles, R. S.; Simon,
   A. A.; Wong, M. H.; Vedovato, M.
2017GeoRL..44.7140F    Altcode: 2017arXiv170805179F
  The dark colors of Jupiter's North Equatorial Belt (NEB, 7-17°N)
  appeared to expand northward into the neighboring zone in 2015,
  consistent with a 3-5 year cycle. Inversions of thermal-IR imaging from
  the Very Large Telescope revealed a moderate warming and reduction of
  aerosol opacity at the cloud tops at 17-20°N, suggesting subsidence and
  drying in the expanded sector. Two new thermal waves were identified
  during this period: (i) an upper tropospheric thermal wave (wave
  number 16-17, amplitude 2.5 K at 170 mbar) in the mid-NEB that was
  anticorrelated with haze reflectivity; and (ii) a stratospheric wave
  (wave number 13-14, amplitude 7.3 K at 5 mbar) at 20-30°N. Both
  were quasi-stationary, confined to regions of eastward zonal flow,
  and are morphologically similar to waves observed during previous
  expansion events.

---------------------------------------------------------
Title: Independent evolution of stratospheric temperatures in
    Jupiter's northern and southern auroral regions from 2014 to 2016
Authors: Sinclair, J. A.; Orton, G. S.; Greathouse, T. K.; Fletcher,
   L. N.; Tao, C.; Gladstone, G. R.; Adriani, A.; Dunn, W.; Moses, J. I.;
   Hue, V.; Irwin, P. G. J.; Melin, H.; Giles, R. S.
2017GeoRL..44.5345S    Altcode:
  We present retrievals of the vertical temperature profile of Jupiter's
  high latitudes from Infrared Telescope Facility-Texas Echelon Cross
  Echelle Spectrograph measurements acquired on 10-11 December 2014 and
  30 April to 1 May 2016. Over this time range, 1 mbar temperature in
  Jupiter's northern and southern auroral regions exhibited independent
  evolution. The northern auroral hot spot exhibited negligible net
  change in temperature at 1 mbar and its longitudinal position remained
  fixed at 180°W (System III), whereas the southern auroral hot spot
  exhibited a net increase in temperature of 11.1 ± 5.2 K at 0.98
  mbar and its longitudinal orientation moved west by approximately
  30°. This southern auroral stratospheric temperature increase might
  be related to (1) near-contemporaneous brightening of the southern
  auroral ultraviolet/near-infrared H3+ emission measured by the Juno
  spacecraft and (2) an increase in the solar dynamical pressure in the
  preceding 3 days. We therefore suggest that 1 mbar temperature in the
  southern auroral region might be modified by higher-energy charged
  particle precipitation.

---------------------------------------------------------
Title: Latitudinal variability in Jupiter's tropospheric
disequilibrium species: GeH<SUB>4</SUB>, AsH<SUB>3</SUB> and
    PH<SUB>3</SUB>
Authors: Giles, R. S.; Fletcher, L. N.; Irwin, P. G. J.
2017Icar..289..254G    Altcode: 2016arXiv161009073G
  Jupiter's tropospheric composition is studied using high-resolution,
  spatially-resolved 5-μm observations from the CRIRES instrument
  at the Very Large Telescope. The high resolving power (R = 96,000)
  allows us to spectrally resolve the line shapes of individual
  molecular species in Jupiter's troposphere and, by aligning the slit
  north-south along Jupiter's central meridian, we are able to search
  for any latitudinal variability. Despite the high spectral resolution,
  we find that there are significant degeneracies between the cloud
  structure and aerosol scattering properties that complicate the
  retrievals of tropospheric gaseous abundances and limit conclusions
  on any belt-zone variability. However, we do find evidence for
  variability between the equatorial regions of the planet and the polar
  regions. Arsine (AsH<SUB>3</SUB>) and phosphine (PH<SUB>3</SUB>) both
  show an enhancement at high latitudes, while the abundance of germane
  (GeH<SUB>4</SUB>) remains approximately constant. These observations
  contrast with the theoretical predictions from Wang et al. (2016)
  and we discuss the possible explanations for this difference.

---------------------------------------------------------
Title: Cycles of activity in the Jovian atmosphere
Authors: Fletcher, L. N.
2017GeoRL..44.4725F    Altcode: 2017arXiv170805180F
  Jupiter's banded appearance may appear unchanging to the casual
  observer, but closer inspection reveals a dynamic, ever-changing system
  of belts and zones with distinct cycles of activity. Identification
  of these long-term cycles requires access to data sets spanning
  multiple Jovian years, but explaining them requires multispectral
  characterization of the thermal, chemical, and aerosol changes
  associated with visible color variations. The Earth-based support
  campaign for Juno's exploration of Jupiter has already characterized
  two upheaval events in the equatorial and temperate belts that are
  part of long-term Jovian cycles, whose underlying sources could be
  revealed by Juno's exploration of Jupiter's deep atmosphere.

---------------------------------------------------------
Title: Non-Gaussian Velocity Distributions in Solar Flares from
Extreme Ultraviolet Lines: A Possible Diagnostic of Ion Acceleration
Authors: Jeffrey, Natasha L. S.; Fletcher, Lyndsay; Labrosse, Nicolas
2017ApJ...836...35J    Altcode: 2017arXiv170102196J
  In a solar flare, a large fraction of the magnetic energy released
  is converted rapidly to the kinetic energy of non-thermal particles
  and bulk plasma motion. This will likely result in non-equilibrium
  particle distributions and turbulent plasma conditions. We investigate
  this by analyzing the profiles of high temperature extreme ultraviolet
  emission lines from a major flare (SOL2014-03-29T17:44) observed by
  the EUV Imaging Spectrometer (EIS) on Hinode. We find that in many
  locations the line profiles are non-Gaussian, consistent with a kappa
  distribution of emitting ions with properties that vary in space and
  time. At the flare footpoints, close to sites of hard X-ray emission
  from non-thermal electrons, the κ index for the Fe xvi 262.976 Å
  line at 3 MK takes values of 3-5. In the corona, close to a low-energy
  HXR source, the Fe xxiii 263.760 Å line at 15 MK shows κ values of
  typically 4-7. The observed trends in the κ parameter show that we are
  most likely detecting the properties of the ion population rather than
  any instrumental effects. We calculate that a non-thermal ion population
  could exist if locally accelerated on timescales ≤0.1 s. However,
  observations of net redshifts in the lines also imply the presence of
  plasma downflows, which could lead to bulk turbulence, with increased
  non-Gaussianity in cooler regions. Both interpretations have important
  implications for theories of solar flare particle acceleration.

---------------------------------------------------------
Title: Summer at Saturn's North Pole: Seasonal Changes Seen by ISS
    &amp; CIRS on Cassini, and VLT on the Ground
Authors: Sayanagi, K. M.; Blalock, J.; Fletcher, L. N.; Ingersoll,
   A. P.; Dyudina, U.; Ewald, S. P.
2016AGUFM.P33B2137S    Altcode:
  We report seasonal changes in Saturn's north polar vortex seen by
  Cassini ISS, Cassini CIRS, and ground-based VLT VISIR thermal infrared
  observations. ISS observation of Saturn's northern high latitudes show
  that a reflective, bright polar spot has formed over the north pole,
  seen first in images captured in 2016. This coincides with the warm
  cyclonic north polar vortex that has been steadily warming since it
  was first discovered in 2007 by Cassini CIRS. The reflective spot was
  not present when the north pole was observed during the previous period
  of Cassini spacecraft's high-inclination orbits in 2012. In 2012, the
  concentration of light-scattering aerosols within 2-degree latitude of
  the north pole appeared to be less than that of the surrounding region,
  and appeared dark in all ISS filters. The new bright spot over the north
  pole is similar to that over the south pole seen in 2007. In 2007,
  Saturn was approaching the equinox of 2009 and south pole had been
  continuously illuminated since the previous equinox in 1995. The bright
  spot over the summer south pole in 2007 was hypothesized to consist
  of aerosols produced by ultraviolet photodissociation of hydrocarbon
  molecules; we follow this hypothesis to propose that the new bright spot
  over the north pole is also produced by the same mechanism. We argue
  that, in 2012 (3 years after equinox), the north polar bright spot
  hadn't formed because the ultraviolet insolation was not sufficient
  to produce enough photochemical aerosols. The new polar bright cloud
  formation is consistent with the rising abundances of stratospheric
  hydrocarbons (potential precursors to aerosol formation) over the north
  polar region as tracked by CIRS (Fletcher et al., 2015). In addition
  to ISS images, we also present CIRS and VLT-VISIR thermal maps of the
  northern high latitudes as the new north polar bright spot is expected
  to have implications on radiative energy balance. Our research has
  been supported by the Cassini Project, NASA grants OPR NNX11AM45G,
  CDAPS NNX15AD33G, PATM NNX14AK07G, and NSF grant AAG 1212216.

---------------------------------------------------------
Title: The strength and evolution of stratospheric-auroral processes
    on Jupiter, as observed by IRTF-TEXES
Authors: Sinclair, J. A.; Orton, G. S.; Greathouse, T. K.; Fletcher,
   L. N.; Moses, J. I.; Hue, V.; Irwin, P. G.; Melin, H.; Giles, R.
2016AGUFM.P33C2149S    Altcode:
  Auroral processes on Jupiter are evident over a large range of
  wavelengths. Juno's JIRAM (Jovian Infrared Auroral Mapper) and UVS
  (Ultraviolet Spectrometer) instruments will observe Jupiter's auroral
  emission at near-infrared and ultraviolet wavelengths, highlighting the
  precipitation of charged particles in Jupiter's thermosphere. These
  observations can then be related to measurements by Juno's MAG
  (magnetometer), JADE (Jovian Auroral Distributions Experiment) and
  JEDI instruments (Jovian Energetic Particle Detector Instrument),
  which will prove a powerful tool in studying the interaction of
  Jupiter's atmosphere with the external magnetosphere. However, Juno's
  scientific payload does not include a mid-infrared instrument (5 -
  15 microns) capable of sounding Jupiter's stratosphere in which a
  significant amount of energy associated with auroral processes is
  deposited. As demonstrated by Sinclair et al., 2016a (under review)
  from a retrieval analysis of Voyager-IRIS (Infrared Interferometer
  Spectrometer) observations in 1979, Cassini-CIRS (Composite Infrared
  Spectrometer) observations in 2001 and IRTF-TEXES (Texas Echelon Cross
  Echelle Spectrograph) observations in 2014, temperatures in the northern
  auroral region at 70°N, 180°W are elevated by up to approximately 20
  K and 35 K at the 1-mbar and 10-ubar levels respectively, in comparison
  to quiescent longitudes (see attached Figure). However, the physical
  mechanisms responsible for modifications of the thermal structure
  and composition of the stratosphere in auroral regions are still not
  well understood. We hope to better understand the processes driving
  the auroral-stratosphere interaction on Jupiter by characterizing
  whether and by what magnitude the thermal structure and composition
  of the stratosphere evolve at Jupiter's high latitudes. In April 2016,
  we obtained IRTF-TEXES measurements of Jupiter's high-latitudes under
  similar conditions to those obtained in December 2014. We will perform
  a retrieval analysis to determine the vertical profiles of temperature,
  C2H2, C2H4 and C2H6. Results will be compared with those in December
  2014 to determine the 3D evolution of the thermal structure and
  composition in proximity to the auroral regions: the attached Figure
  shows preliminary temperature results.

---------------------------------------------------------
Title: Arcade Implosion Caused by a Filament Eruption in a Flare
Authors: Wang, Juntao; Simões, P. J. A.; Fletcher, L.; Thalmann,
   J. K.; Hudson, H. S.; Hannah, I. G.
2016ApJ...833..221W    Altcode: 2016arXiv161005931W
  Coronal implosions—the convergence motion of plasmas and entrained
  magnetic field in the corona due to a reduction in magnetic
  pressure—can help to locate and track sites of magnetic energy
  release or redistribution during solar flares and eruptions. We report
  here on the analysis of a well-observed implosion in the form of an
  arcade contraction associated with a filament eruption, during the
  C3.5 flare SOL2013-06-19T07:29. A sequence of events including the
  magnetic flux-rope instability and distortion, followed by a filament
  eruption and arcade implosion, lead us to conclude that the implosion
  arises from the transfer of magnetic energy from beneath the arcade
  as part of the global magnetic instability, rather than due to local
  magnetic energy dissipation in the flare. The observed net contraction
  of the imploding loops, which is found also in nonlinear force-free
  field extrapolations, reflects a permanent reduction of magnetic
  energy underneath the arcade. This event shows that, in addition to
  resulting in the expansion or eruption of an overlying field, flux-rope
  instability can also simultaneously implode an unopened field due to
  magnetic energy transfer. It demonstrates the “partial opening of
  the field” scenario, which is one of the ways in 3D to produce a
  magnetic eruption without violating the Aly-Sturrock hypothesis. In
  the framework of this observation, we also propose a unification of
  three main concepts for active region magnetic evolution, namely the
  metastable eruption model, the implosion conjecture, and the standard
  “CSHKP” flare model.

---------------------------------------------------------
Title: SPRITE - The Saturn PRobe Interior and aTmosphere Explorer
    Mission.
Authors: Atkinson, D. H.; Simon, A. A.; Banfield, D. J.; Atreya,
   S. K.; Blacksberg, J.; Brinckerhoff, W. B.; Colaprete, A.; Coustenis,
   A.; Danner, R. M.; Fletcher, L. N.; Guillot, T.; Hofstadter, M. D.;
   Keithly, D.; Lobbia, M. A.; Lunine, J. I.; Mahaffy, P. R.; Marley,
   M. S.; Mousis, O.; Spilker, T. R.; Trainer, M. G.; Webster, C. R.;
   Youmans, T. A.
2016AGUFM.P33B2132A    Altcode:
  The 2013-2022 Planetary Science Decadal Survey (PSDS) Vision and Voyages
  Planetary identified a Saturn Probe mission as a high priority mission
  target for the NASA New Frontiers program. Fundamental measurements of
  noble gas abundances and isotope ratios of hydrogen, carbon, oxygen,
  and nitrogen, as well as the interior structure of Saturn are needed to
  help constrain Solar System formation models and to provide an improved
  context for understanding exoplanet systems. The SPRITE mission would
  fulfill the PSDS scientific goals for in situ exploration of Saturn, and
  would additionally provide ground truth for remote sensing that would
  improve the understanding of the composition and interior structure of
  Saturn and, by proxy, extrasolar giant planets. In Situ measurements are
  the only means to address many key questions regarding the structure
  and composition of Saturn's atmosphere including the abundance of
  noble gases and key isotopes, the abundance of helium needed to
  understand the formation history and thermal evolution of Saturn,
  and the abundance of water in the deep atmosphere, a key diagnostic
  of Saturn's formation since it is thought that the heavy elements were
  delivered by water-bearing planetesimals. The SPRITE atmospheric entry
  probe mission including remote sensing from a carrier-relay spacecraft
  would measure many of these key atmospheric constituents as well as
  the atmospheric structure of Saturn including temperature, pressure
  and wind speeds along the probe descent path thereby providing interior
  science not accessible to remote sensing measurements. Additionally, the
  SPRITE carrier-relay spacecraft would make remote sensing measurements
  to support probe measurements in the upper troposphere of Saturn.

---------------------------------------------------------
Title: Analysis of Saturn's Hexagon between 2012 and 2016: Dynamical
    and Morphological Changes
Authors: Blalock, J.; Sayanagi, K. M.; Fletcher, L. N.; Ingersoll,
   A. P.; Dyudina, U.; Ewald, S. P.
2016AGUFM.P31D..06B    Altcode:
  We present analyses of Saturn's wind fields and cloud morphology in
  the northern Hexagon region, combining visible-light imaging from the
  Cassini ISS instrument with measurements of Saturn's thermal structure
  and zonal wind shear from the Cassini CIRS instrument and ground-based
  VLT/VISIR imaging. Our study focuses on temporal changes occurring
  in the region around 77 degree N planetocentric latitude, which has
  been illuminated by sunlight since 2008, and captured by ISS with good
  observation geometries in 2012-2013 and 2016. The goal of our analysis
  is to detect any change in the cloud morphology, atmospheric dynamics
  and thermal structure. To measure the wind field in the Hexagon region,
  we utilize the two-dimensional correlation imaging velocimetry (CIV)
  technique. We also calculate the relative vorticity and divergence from
  the wind field. To detect changes in the dynamics of the Hexagon, we
  compare measurements of the wind, relative vorticity, and divergence
  in 2012 with those from 2016, as well as evaluating changes in the
  zonal mean temperature gradient across the Hexagon boundaries. We
  compare cloud reflectivity between 2012 and 2016 in images that
  show the Hexagon under similar illumination conditions, calculating
  the zonal mean reflectivity as a function of latitude. Furthermore,
  we assess the winds and cloud reflectivity at several wavelengths in
  order to look for changes occurring at different altitudes, and relate
  this to temperature variations in the 100-700 mbar region assessed from
  Cassini and ground-based VLT imaging. Specifically, we focus on the CB2
  continuum filter which senses thick tropospheric clouds and the MT2 and
  MT3 methane filters which sense the upper tropospheric and stratospheric
  haze layers. Our work has been supported by NASA PATM NNX14AK07G,
  CDAPS NNX15AD33G, NSF AAG 1212216, and NASA NESSF NNX15AQ70H.

---------------------------------------------------------
Title: Photochemistry in Saturn's Ring-Shadowed Atmosphere: Modulation
    of Hydrocarbons and Observations of Dust Content
Authors: Edgington, S. G.; Atreya, S. K.; Wilson, E. H.; Baines,
   K. H.; West, R. A.; Bjoraker, G. L.; Fletcher, L. N.; Momary, T.
2016AGUFM.P33B2133E    Altcode:
  Cassini has been orbiting Saturn for over twelve years now. During this
  epoch, the ring shadow has moved from covering much of the northern
  hemisphere with solar inclination of 24 degrees to covering a large
  swath south of the equator and it continues to move southward. At
  Saturn Orbit Insertion in 2004, the projection of the A-ring onto
  Saturn reached as far as 40N along the central meridian (52N at
  the terminator). At its maximum extent, the ring shadow can reach
  as far as 48N/S (58N/S at the terminator). The net effect is that
  the intensity of both ultraviolet and visible sunlight penetrating
  through the rings to any particular latitude will vary depending on
  both Saturn's axis relative to the Sun and the optical thickness of
  each ring system. In essence, the rings act like semi-transparent
  venetian blinds.Previous work examined the variation of the solar
  flux as a function of solar inclination, i.e. for each 7.25-year
  season at Saturn. Here, we report on the impact of the oscillating
  ring shadow on the photolysis and production rates of hydrocarbons
  (acetylene, ethane, propane, and benzene) and phosphine in Saturn's
  stratosphere and upper troposphere. The impact of these production
  and loss rates on the abundance of long-lived photochemical products
  leading to haze formation are explored. We assess their impact on
  phosphine abundance, a disequilibrium species whose presence in the
  upper troposphere can be used as a tracer of convective processes in
  the deeper atmosphere.We will also present our ongoing analysis of
  Cassini's CIRS, UVIS, and VIMS datasets that provide an estimate of the
  evolving haze content of the northern hemisphere and we will begin to
  assess the implications for dynamical mixing. In particular, we will
  examine how the now famous hexagonal jet stream acts like a barrier to
  transport, isolating Saturn's north polar region from outside transport
  of photochemically-generated molecules and haze.The research described
  in this paper was carried out in part at the Jet Propulsion Laboratory,
  California Institute of Technology, under a contract with the National
  Aeronautics and Space Administration. Copyright 2016 California
  Institute of Technology. Government sponsorship is acknowledged.

---------------------------------------------------------
Title: Evidence for kappa distributions of ions in the flaring solar
    atmosphere from extreme ultraviolet spectroscopy
Authors: Fletcher, L.; Jeffrey, N. L. S.; Labrosse, N.
2016AGUFMSH13D..02F    Altcode:
  We present new evidence for ion kappa distributions in the lower
  solar atmosphere, and in the solar corona, during the impulsive
  energy release phase of solar flares. The existence of non-Maxwellian
  electron distributions during flares is well established from X-ray
  spectroscopy, but ion populations are harder to diagnose. By careful
  fitting of the spectral line profiles from highly ionised states
  of iron observed during flares by the Extreme Ultraviolet Imaging
  Spectrometer (EIS) on the Hinode spacecraft, and taking into account
  the spectrometer's known instrumental characteristics, we establish
  that the physical line profile is consistent with that emitted by a
  kappa distribution of ions. Kappa distributions provide a far better
  fit than Maxwellian distributions in many cases, and are detected both
  at the chromospheric footpoints and in the corona during flares, but
  with different parameters. We discuss the possible origins of these ion
  distributions, and their implications for solar flare ion acceleration.

---------------------------------------------------------
Title: Tapping the Core - a study of Alfvénic energy flow in an
    erupting flux-rope configuration
Authors: Fletcher, L.; Dalmasse, K.; Gibson, S. E.; Fan, Y.
2016AGUFMSH31B2564F    Altcode:
  We analyze the evolution of reconnecting magnetic field in a 3-D
  numerical simulation of a partially-ejected solar flux rope, with a
  focus on understanding how the flux rope dynamics is linked to the
  flow of energy through the field and the solar atmosphere as Alfvénic
  Poynting flux. The magnetic flux rope splits in two during its eruption,
  with reconnection taking place between the erupting rope and surrounding
  fields, and internally in the strong field of the rope. We track the
  Poynting flux entering and leaving the simulation current sheets,
  and by mapping this down to the solar surface we identify locations of
  weak and strong energy deposition in the lower atmosphere. Our tracking
  method enables us to link the lower atmosphere signatures to different
  stages of the coronal reconnection. We find a predominantly two-ribbon
  morphology in the locations of Poynting flux deposition in the lower
  atmosphere, in which the transition from reconnection involving weaker
  field external to the flux rope, to reconnection involving the flux rope
  core field, is accompanied by rapid ribbon spreading. In the core-field
  reconnection phase, ribbons move into strong field regions on the
  solar surface, and locations of highly concentrated downward-directed
  Poynting flux are found, which may be linked to the most energetic flare
  `footpoints' seen in optical and hard X-ray emission.

---------------------------------------------------------
Title: Recruiting flare hunters for citizen science
Authors: Fletcher, Lyndsay; Berlicki, Arkadiusz; Awasthi, Arun Kumar;
   Gronkiewicz, Dominik
2016A&G....57f6.21F    Altcode:
  Lyndsay Fletcher, Arkadiusz Berlicki, Arun Kumar Awasthi and Dominik
  Gronkiewicz describe how they established F-HUNTERS, a pro-am solar
  flare observing campaign.

---------------------------------------------------------
Title: Doppler speeds of the hydrogen Lyman lines in solar flares
    from EVE
Authors: Brown, Stephen A.; Fletcher, Lyndsay; Labrosse, Nicolas
2016A&A...596A..51B    Altcode: 2016arXiv161004007B
  <BR /> Aims: The hydrogen Lyman lines provide important diagnostic
  information about the dynamics of the chromosphere, but there have
  been few systematic studies of their variability during flares. We
  investigate Doppler shifts in these lines in several flares, and use
  these to calculate plasma speeds. <BR /> Methods: We use spectral data
  from the Multiple EUV Grating Spectrograph B (MEGS-B) detector of the
  Extreme-Ultraviolet Variability Experiment (EVE) instrument on the Solar
  Dynamics Observatory. MEGS-B obtains full-disk spectra of the Sun at
  a resolution of 0.1 nm in the range 37-105 nm, which we analyse using
  three independent methods. The first method performs Gaussian fits to
  the lines, and compares the quiet-Sun centroids with the flaring ones
  to obtain the Doppler shifts. The second method uses cross-correlation
  to detect wavelength shifts between the quiet-Sun and flaring line
  profiles. The final method calculates the "center-of-mass" of the line
  profile, and compares the quiet-Sun and flaring centroids to obtain the
  shift. <BR /> Results: In a study of 6 flares we find strong signatures
  of both upflow and downflow in the Lyman lines, with speeds measured
  in Sun-as-a-Star data of around 10 km s<SUP>-1</SUP>, and speeds in the
  flare excess signal of around 30 km s<SUP>-1</SUP>. <BR /> Conclusions:
  All events showing upflows in Lyman lines are associated with some kind
  of eruption or coronal flow in imaging data, which may be responsible
  for the net blueshifts. Events showing downflows in the Lyman lines
  may be associated with loop contraction or faint downflows, but it is
  likely that chromospheric condensation flows are also contributing.

---------------------------------------------------------
Title: Doppler speeds of the hydrogen Lyman lines in solar flares
    from EVE
Authors: Brown, Stephen; Fletcher, Lyndsay; Labrosse, Nicolas
2016usc..confE...7B    Altcode:
  The hydrogen Lyman lines provide important diagnostic information
  about the dynamics of the chromosphere, but until recently there have
  been few systematic studies of their variability during flares. We
  investigate Doppler shifts in these lines in several flares, and
  use these to calculate plasma speeds. We use spectral data from the
  Multiple EUV Grating Spectrograph B (MEGS-B) detector on board the
  Extreme-Ultraviolet Variability Experiment (EVE) instrument on the Solar
  Dynamics Observatory. MEGS-B obtains full-disk spectra of the Sun at
  a resolution of 0.1nm in the range 37-105nm, which we analyse using
  three independent methods. The first method performs Gaussian fits to
  the lines, and compares the quiet-Sun centroids with the flaring ones
  to obtain the Doppler shifts. The second method uses cross-correlation
  to detect wavelength shifts between the quiet-Sun and flaring line
  profiles. The final method calculates the "center-of-mass" of the line
  profile, and compares the quiet-Sun and flaring centroids to obtain
  the shift. In a study of 6 flares we find signatures of both upflow
  and downflow in the Lyman lines, with speeds of around 10 km s^-1 in
  the line profiles that have not undergone pre-flare subtraction, and
  speeds in the flare-excess profiles of around 30 km s^-1 . We include
  analysis of AIA images of these events in order to understand potential
  contributions from material ejections, and find that not all upflows
  can be explained by ejecta. We discuss current and future attempts at
  modelling these line profiles.

---------------------------------------------------------
Title: The Hera Saturn entry probe mission
Authors: Mousis, O.; Atkinson, D. H.; Spilker, T.; Venkatapathy, E.;
   Poncy, J.; Frampton, R.; Coustenis, A.; Reh, K.; Lebreton, J. -P.;
   Fletcher, L. N.; Hueso, R.; Amato, M. J.; Colaprete, A.; Ferri, F.;
   Stam, D.; Wurz, P.; Atreya, S.; Aslam, S.; Banfield, D. J.; Calcutt,
   S.; Fischer, G.; Holland, A.; Keller, C.; Kessler, E.; Leese, M.;
   Levacher, P.; Morse, A.; Muñoz, O.; Renard, J. -B.; Sheridan, S.;
   Schmider, F. -X.; Snik, F.; Waite, J. H.; Bird, M.; Cavalié, T.;
   Deleuil, M.; Fortney, J.; Gautier, D.; Guillot, T.; Lunine, J. I.;
   Marty, B.; Nixon, C.; Orton, G. S.; Sánchez-Lavega, A.
2016P&SS..130...80M    Altcode: 2015arXiv151007685M
  The Hera Saturn entry probe mission is proposed as an M-class mission
  led by ESA with a contribution from NASA. It consists of one atmospheric
  probe to be sent into the atmosphere of Saturn, and a Carrier-Relay
  spacecraft. In this concept, the Hera probe is composed of ESA
  and NASA elements, and the Carrier-Relay Spacecraft is delivered
  by ESA. The probe is powered by batteries, and the Carrier-Relay
  Spacecraft is powered by solar panels and batteries. We anticipate
  two major subsystems to be supplied by the United States, either by
  direct procurement by ESA or by contribution from NASA: the solar
  electric power system (including solar arrays and the power management
  and distribution system), and the probe entry system (including the
  thermal protection shield and aeroshell). Hera is designed to perform
  in situ measurements of the chemical and isotopic compositions as
  well as the dynamics of Saturn's atmosphere using a single probe, with
  the goal of improving our understanding of the origin, formation, and
  evolution of Saturn, the giant planets and their satellite systems,
  with extrapolation to extrasolar planets. Hera's aim is to probe
  well into the cloud-forming region of the troposphere, below the
  region accessible to remote sensing, to the locations where certain
  cosmogenically abundant species are expected to be well mixed. By
  leading to an improved understanding of the processes by which giant
  planets formed, including the composition and properties of the local
  solar nebula at the time and location of giant planet formation,
  Hera will extend the legacy of the Galileo and Cassini missions by
  further addressing the creation, formation, and chemical, dynamical,
  and thermal evolution of the giant planets, the entire solar system
  including Earth and the other terrestrial planets, and formation of
  other planetary systems.

---------------------------------------------------------
Title: A dispersive wave pattern on Jupiter's fastest retrograde
    jet at 20°S
Authors: Rogers, J. H.; Fletcher, L. N.; Adamoli, G.; Jacquesson,
   M.; Vedovato, M.; Orton, G. S.
2016Icar..277..354R    Altcode: 2016arXiv160507883R
  A compact wave pattern has been identified on Jupiter's fastest
  retrograding jet at 20°S (the SEBs) on the southern edge of the
  South Equatorial Belt. The wave has been identified in both reflected
  sunlight from amateur observations between 2010 and 2015, thermal
  infrared imaging from the Very Large Telescope and near infrared
  imaging from the Infrared Telescope Facility. The wave pattern is
  present when the SEB is relatively quiescent and lacking large-scale
  disturbances, and is particularly notable when the belt has undergone a
  fade (whitening). It is generally not present when the SEB exhibits its
  usual large-scale convective activity ('rifts'). Tracking of the wave
  pattern and associated white ovals on its southern edge over several
  epochs have permitted a measure of the dispersion relationship, showing
  a strong correlation between the phase speed (-43.2 to -21.2 m/s) and
  the longitudinal wavelength, which varied from 4.4 to 10.0° longitude
  over the course of the observations. Infrared imaging sensing low
  pressures in the upper troposphere suggest that the wave is confined
  to near the cloud tops. The wave is moving westward at a phase speed
  slower (i.e., less negative) than the peak retrograde wind speed
  (-62 m/s), and is therefore moving east with respect to the SEBs jet
  peak. Unlike the retrograde NEBn jet near °N, which is a location of
  strong vertical wind shear that sometimes hosts Rossby wave activity,
  the SEBs jet remains retrograde throughout the upper troposphere,
  suggesting the SEBs pattern cannot be interpreted as a classical Rossby
  wave. 2D windspeeds and thermal gradients measured by Cassini in 2000
  are used to estimate the quasi-geostrophic potential vorticity gradient
  as a means of understanding the origin of the a wave. We find that
  the vorticity gradient is dominated by the baroclinic term and becomes
  negative (changes sign) in a region near the cloud-top level (400-700
  mbar) associated with the SEBs. Such a sign reversal is a necessary (but
  not sufficient) condition for the growth of baroclinic instabilities,
  which is a potential source of the meandering wave pattern.

---------------------------------------------------------
Title: A pioneer of solar astronomy
Authors: Dalla, Silvia; Fletcher, Lyndsay
2016A&G....57e5.21D    Altcode:
  Silvia Dalla and Lyndsay Fletcher assess the work of Annie Maunder,
  an outstanding observer and interpreter of observations, who argued
  for her innovative ideas with power and eloquence.

---------------------------------------------------------
Title: Simulations of the Mg II k and Ca II 8542 lines from an
    AlfvÉn Wave-heated Flare Chromosphere
Authors: Kerr, Graham S.; Fletcher, Lyndsay.; Russell, Alexander J. B.;
   Allred, Joel C.
2016ApJ...827..101K    Altcode: 2016arXiv160505888K
  We use radiation hydrodynamic simulations to examine two models of solar
  flare chromospheric heating: Alfvén wave dissipation and electron beam
  collisional losses. Both mechanisms are capable of strong chromospheric
  heating, and we show that the distinctive atmospheric evolution in
  the mid-to-upper chromosphere results in Mg II k-line emission that
  should be observably different between wave-heated and beam-heated
  simulations. We also present Ca II 8542 Å profiles that are formed
  slightly deeper in the chromosphere. The Mg II k-line profiles from our
  wave-heated simulation are quite different from those from a beam-heated
  model and are more consistent with Interface Region Imaging Spectrograph
  observations. The predicted differences between the Ca II 8542 Å in
  the two models are small. We conclude that careful observational and
  theoretical study of lines formed in the mid-to-upper chromosphere
  holds genuine promise for distinguishing between competing models for
  chromospheric heating in flares.

---------------------------------------------------------
Title: Flares In Time-Domain Surveys
Authors: Kowalski, Adam; Hawley, Suzanne; Davenport, James; Berlicki,
   Arkadiusz; Cauzzi, Gianna; Fletcher, Lyndsay; Heinzel, Petr; Notsu,
   Yuta; Loyd, Parke; Martinez Oliveros, Juan Carlos; Pugh, Chloe;
   Schmidt, Sarah Jane; Karmakar, Subhajeet; Pye, John; Flaccomio, Ettore
2016csss.confE.126K    Altcode:
  Proceedings for the splinter session "Flares in Time-Domain Surveys"
  convened at Cool Stars 19 on June 07, 2016 in Uppsala, Sweden. Contains
  a two page summary of the splinter session, links to YouTube talks,
  and a PDF copy of the slides from the presenters.

---------------------------------------------------------
Title: Probing Saturn's tropospheric cloud with Cassini/VIMS
Authors: Barstow, J. K.; Irwin, P. G. J.; Fletcher, L. N.; Giles,
   R. S.; Merlet, C.
2016Icar..271..400B    Altcode: 2016arXiv160102978B
  In its decade of operation the Cassini mission has allowed us to look
  deep into Saturn's atmosphere and investigate the processes occurring
  below its enshrouding haze. We use Visual and Infrared Mapping
  Spectrometer (VIMS) 4.6-5.2 μm data from early in the mission to
  investigate the location and properties of Saturn's cloud structure
  between 0.6 and 5 bar. We average nightside spectra from 2006 over
  latitude circles and model the spectral limb darkening using the NEMESIS
  radiative transfer and retrieval tool. We present our best-fit deep
  cloud model for latitudes -40<SUP>∘</SUP> &lt; λ &lt;50<SUP>∘</SUP>
  , along with retrieved abundances for NH<SUB>3</SUB>, PH<SUB>3</SUB> and
  AsH<SUB>3</SUB>. We find an increase in NH<SUB>3</SUB> abundance at the
  equator, a cloud base at ∼2.3 bar and no evidence for cloud particles
  with strong absorption features in the 4.6-5.2 μm wavelength range, all
  of which are consistent with previous work. Non-scattering cloud models
  assuming a composition of either NH<SUB>3</SUB> or NH<SUB>4</SUB>SH,
  with a scattering haze overlying, fit limb darkening curves and
  spectra at all latitudes well; the retrieved optical depth for the
  tropospheric haze is decreased in the northern (winter) hemisphere,
  implying that the haze has a photochemical origin. Our ability to test
  this hypothesis by examining spectra at different seasons is restricted
  by the varying geometry of VIMS observations over the life of the
  mission, and the appearance of the Saturn storm towards the end of 2010.

---------------------------------------------------------
Title: Time variability of Neptune's horizontal and vertical cloud
    structure revealed by VLT/SINFONI and Gemini/NIFS from 2009 to 2013
Authors: Irwin, P. G. J.; Fletcher, L. N.; Tice, D.; Owen, S. J.;
   Orton, G. S.; Teanby, N. A.; Davis, G. R.
2016Icar..271..418I    Altcode:
  New observations of Neptune's clouds in the near infrared were acquired
  in October 2013 with SINFONI on ESO's Very Large Telescope (VLT) in
  Chile. SINFONI is an Integral Field Unit spectrometer returning a 64
  × 64 pixel image with 2048 wavelengths. Image cubes in the J-band
  (1.09-1.41 μm) and H-band (1.43-1.87 μm) were obtained at spatial
  resolutions of 0.1″and 0.025″per pixel, while SINFONI's adaptive
  optics provided an effective resolution of approximately 0.1″. Image
  cubes were obtained at the start and end of three successive nights
  to monitor the temporal development of discrete clouds both at short
  timescales (i.e. during a single night) as well as over the longer
  period of the three-day observing run. These observations were compared
  with similar H-band observations obtained in September 2009 with the
  NIFS Integral Field Unit spectrometer on the Gemini-North telescope
  in Hawaii, previously reported by Irwin et al. (2011) [Icarus, 216,
  141-158], and previously unreported Gemini/NIFS observations at lower
  spatial resolution made in 2011. <P />We find both similarities and
  differences between these observations, spaced over four years. The
  same overall cloud structure is seen with high, bright clouds visible
  at mid-latitudes (30-40°N,S), with slightly lower clouds observed
  at lower latitudes, together with small discrete clouds seen circling
  the pole at a latitude of approximately 60°S. However, while discrete
  clouds were visible at this latitude at both the main cloud deck level
  (at 2-3 bar) and in the upper troposphere (100-500 mb) in 2009, no
  distinct deep (2-3 bar), discrete circumpolar clouds were visible
  in 2013, although some deep clouds were seen at the southern edge
  of the main cloud belt at 30-40°S, which have not been observed
  before. The nature of the deep sub-polar discrete clouds observed in
  2009 is intriguing. While it is possible that in 2013 these deeper
  clouds were masked by faster moving, overlying features, we consider
  that it is unlikely that this should have happened in 2013, but not in
  2009 when the upper-cloud activity was generally similar. Meanwhile,
  the deep clouds seen at the southern edge of the main cloud belt at
  30-40°S in 2013, should also have been detectable in 2009, but were
  not seen. Hence, these observations may have detected a real temporal
  variation in the occurrence of Neptune's deep clouds, pointing to
  underlying variability in the convective activity at the pressure of
  the main cloud deck at 2-3 bar near Neptune's south pole and also in
  the main observable cloud belt at 30-40°S.

---------------------------------------------------------
Title: First evidence of non-Gaussian solar flare EUV spectral line
    profiles and accelerated non-thermal ion motion
Authors: Jeffrey, Natasha L. S.; Fletcher, Lyndsay; Labrosse, Nicolas
2016A&A...590A..99J    Altcode: 2016arXiv160107308J
  Context. The properties of solar flare plasma can be determined from
  the observation of optically thin lines. The emitting ion distribution
  determines the shape of the spectral line profile, with an isothermal
  Maxwellian ion distribution producing a Gaussian profile. Non-Gaussian
  line profiles may indicate more complex ion distributions. <BR />
  Aims: We investigate the possibility of determining flare-accelerated
  non-thermal ion and/or plasma velocity distributions. <BR /> Methods:
  We study EUV spectral lines produced during a flare SOL2013-05-15T01:45
  using the Hinode EUV Imaging Spectrometer (EIS). The flare is located
  close to the eastern solar limb with an extended loop structure,
  allowing the different flare features: ribbons, hard X-ray (HXR)
  footpoints and the loop-top source to be clearly observed in UV, EUV and
  X-rays. EUV line spectroscopy is performed in seven different regions
  covering the flare. We study the line profiles of the isolated and
  unblended Fe XVI lines (λ262.9760 Å ) mainly formed at temperatures
  of ~2 to 4 MK. Suitable Fe XVI line profiles at one time close to
  the peak soft X-ray emission and free of directed mass motions are
  examined using: 1. a higher moments analysis, 2. Gaussian fitting,
  and 3. by fitting a kappa distribution line profile convolved with a
  Gaussian to account for the EIS instrumental profile. <BR /> Results:
  Fe XVI line profiles in the flaring loop-top, HXR footpoint and ribbon
  regions can be confidently fitted with a kappa line profile with an
  extra variable κ, giving low, non-thermal κ values between 2 and
  3.3. An independent higher moments analysis also finds that many of the
  spectral line kurtosis values are higher than the Gaussian value of 3,
  even with the presence of a broad Gaussian instrumental profile. <BR
  /> Conclusions: A flare-accelerated non-thermal ion population could
  account for both the observed non-Gaussian line profiles, and for the
  Fe XVI "excess" broadening found from Gaussian fitting, if the emitting
  ions are interacting with a thermalised ~4 MK electron population,
  and the instrumental profile is well-approximated by a Gaussian profile.

---------------------------------------------------------
Title: Detection of H<SUB>3</SUB><SUP>+</SUP> auroral emission in
    Jupiter's 5-micron window
Authors: Giles, R. S.; Fletcher, L. N.; Irwin, P. G. J.; Melin, H.;
   Stallard, T. S.
2016A&A...589A..67G    Altcode: 2016arXiv160303646G
  We use high-resolution ground-based observations from the VLT
  CRIRES instrument in November 2012 to identify sixteen previously
  undetected H<SUB>3</SUB><SUP>+</SUP> emission lines from Jupiter's
  ionosphere. These emission lines are located in Jupiter's 5-micron
  window (4.5-5.2 μm), an optically-thin region of the planet's spectrum
  where the radiation mostly originates from the deep troposphere. The
  H<SUB>3</SUB><SUP>+</SUP> emission lines are so strong that they are
  visible even against this bright background. We measure the Doppler
  broadening of the H<SUB>3</SUB><SUP>+</SUP> emission lines in order to
  evaluate the kinetic temperature of the molecules, and we obtain a value
  of 1390 ± 160 K. We also measure the relative intensities of lines in
  the ν<SUB>2</SUB> fundamental in order to calculate the rotational
  temperature, obtaining a value of 960 ± 40 K. Finally, we use the
  detection of an emission line from the 2ν<SUB>2</SUB>(2)-ν<SUB>2</SUB>
  overtone to measure a vibrational temperature of 925 ± 25 K. We
  use these three independent temperature estimates to discuss the
  thermodynamic equilibrium of Jupiter's ionosphere.

---------------------------------------------------------
Title: Telling twins apart: exo-Earths and Venuses with transit
    spectroscopy
Authors: Barstow, J. K.; Aigrain, S.; Irwin, P. G. J.; Kendrew, S.;
   Fletcher, L. N.
2016MNRAS.458.2657B    Altcode: 2016arXiv160208277B; 2016MNRAS.tmp..271B
  The planned launch of the James Webb Space Telescope (JWST) in
  2018 will herald a new era of exoplanet spectroscopy. JWST will be
  the first telescope sensitive enough to potentially characterize
  terrestrial planets from their transmission spectra. In this work,
  we explore the possibility that terrestrial planets with Venus-type
  and Earth-type atmospheres could be distinguished from each other
  using spectra obtained by JWST. If we find a terrestrial planet close
  to the liquid water habitable zone of an M5 star within a distance
  of 10 parsec, it would be possible to detect atmospheric ozone if
  present in large enough quantities, which would enable an oxygen-rich
  atmosphere to be identified. However, the cloudiness of a Venus-type
  atmosphere would inhibit our ability to draw firm conclusions about
  the atmospheric composition, making any result ambiguous. Observing
  small, temperate planets with JWST requires significant investment of
  resources, with single targets requiring of the order of 100 transits
  to achieve sufficient signal to noise. The possibility of detecting a
  crucial feature such as the ozone signature would need to be carefully
  weighed against the likelihood of clouds obscuring gas absorption in
  the spectrum.

---------------------------------------------------------
Title: Observations and Modelling of Helium Lines in Solar Flares
Authors: Simões, P. J. A.; Fletcher, L.; Labrosse, N.; Kerr, G. S.
2016ASPC..504..197S    Altcode: 2015arXiv151203477S
  We explore the response of the He &lt;small&gt;II&lt;/small&gt; 304
  Å and He &lt;small&gt;I&lt;/small&gt; 584 Å line intensities to
  electron beam heating in solar flares using radiative hydrodynamic
  simulations. Comparing different electron beams parameters, we found
  that the intensities of both He lines are very sensitive to the energy
  flux deposited in the chromosphere, or more specifically to the heating
  rate, with He &lt;font size=2&gt;II 304 Å being more sensitive to the
  heating than He &lt;small&gt;I&lt;/small&gt; 584 Å. Therefore, the He
  line ratio increases for larger heating rates in the chromosphere. A
  similar trend is found in observations, using SDO/EVE He irradiance
  ratios and estimates of the electron beam energy rate obtained from
  hard X-ray data. From the simulations, we also found that spectral
  index of the electrons can affect the He ratio but a similar effect
  was not found in the observations.

---------------------------------------------------------
Title: Division E Commission 10: Solar Activity
Authors: Schrijver, Carolus J.; Fletcher, Lyndsay; van Driel-Gesztelyi,
   Lidia; Asai, Ayumi; Cally, Paul S.; Charbonneau, Paul; Gibson, Sarah
   E.; Gomez, Daniel; Hasan, Siraj S.; Veronig, Astrid M.; Yan, Yihua
2016IAUTA..29..245S    Altcode: 2015arXiv151003348S
  After more than half a century of community support related to the
  science of “solar activity”, IAU's Commission 10 was formally
  discontinued in 2015, to be succeeded by C.E2 with the same area
  of responsibility. On this occasion, we look back at the growth of
  the scientific disciplines involved around the world over almost a
  full century. Solar activity and fields of research looking into the
  related physics of the heliosphere continue to be vibrant and growing,
  with currently over 2,000 refereed publications appearing per year from
  over 4,000 unique authors, publishing in dozens of distinct journals
  and meeting in dozens of workshops and conferences each year. The
  size of the rapidly growing community and of the observational and
  computational data volumes, along with the multitude of connections
  into other branches of astrophysics, pose significant challenges;
  aspects of these challenges are beginning to be addressed through,
  among others, the development of new systems of literature reviews,
  machine-searchable archives for data and publications, and virtual
  observatories. As customary in these reports, we highlight some
  of the research topics that have seen particular interest over the
  most recent triennium, specifically active-region magnetic fields,
  coronal thermal structure, coronal seismology, flares and eruptions,
  and the variability of solar activity on long time scales. We close
  with a collection of developments, discoveries, and surprises that
  illustrate the range and dynamics of the discipline.

---------------------------------------------------------
Title: The Europa Imaging System (EIS): High-Resolution Imaging and
    Topography to Investigate Europa's Geology, Ice Shell, and Potential
    for Current Activity
Authors: Turtle, E. P.; McEwen, A. S.; Collins, G. C.; Fletcher, L.;
   Hansen, C. J.; Hayes, A. G.; Hurford, T. A.; Kirk, R. L.; Barr Mlinar,
   A. C.; Nimmo, F.; Patterson, G. W.; Quick, L. C.; Soderblom, J. M.;
   Thomas, N.; Ernst, C. M.
2016LPI....47.1626T    Altcode:
  Cameras to reveal / Europa's fractured landscapes / Ice shell mysteries.

---------------------------------------------------------
Title: Structures in the Outer Solar Atmosphere
Authors: Fletcher, L.; Cargill, P. J.; Antiochos, S. K.; Gudiksen,
   B. V.
2016mssf.book..231F    Altcode:
  No abstract at ADS

---------------------------------------------------------
Title: Spectral analysis of Uranus' 2014 bright storm with VLT/SINFONI
Authors: Irwin, P. G. J.; Fletcher, L. N.; Read, P. L.; Tice, D.;
   de Pater, I.; Orton, G. S.; Teanby, N. A.; Davis, G. R.
2016Icar..264...72I    Altcode: 2015arXiv151002274I
  An extremely bright storm system observed in Uranus' atmosphere
  by amateur observers in September 2014 triggered an international
  campaign to observe this feature with many telescopes across the
  world. Observations of the storm system in the near infrared were
  acquired in October and November 2014 with SINFONI on ESO's Very
  Large Telescope (VLT) in Chile. SINFONI is an Integral Field Unit
  spectrometer returning 64 × 64 pixel images with 2048 wavelengths
  and uses adaptive optics. Image cubes in the H-band (1.43-1.87 μm)
  were obtained at spatial resolutions of ∼ 0.1″ per pixel. <P
  />The observations show that the centre of the storm feature shifts
  markedly with increasing altitude, moving in the retrograde direction
  and slightly poleward with increasing altitude. We also see a faint
  'tail' of more reflective material to the immediate south of the
  storm, which again trails in the retrograde direction. The observed
  spectra were analysed with the radiative transfer and retrieval code,
  NEMESIS (Irwin et al. [2008]. J. Quant. Spec. Radiat. Transfer, 109,
  1136-1150). We find that the storm is well-modelled using either two
  main cloud layers of a 5-layer aerosol model based on Sromovsky et
  al. (Sromovsky et al. [2011]. Icarus, 215, 292-312) or by the simpler
  two-cloud-layer model of Tice et al. (Tice et al. [2013]. Icarus,
  223, 684-698). The deep component appears to be due to a brightening
  (i.e. an increase in reflectivity) and increase in altitude of the
  main tropospheric cloud deck at 2-3 bars for both models, while the
  upper component of the feature was modelled as being due to either a
  thickening of the tropospheric haze of the 2-layer model or a vertical
  extension of the upper tropospheric cloud of the 5-layer model, assumed
  to be composed of methane ice and based at the methane condensation
  level of our assumed vertical temperature and abundance profile at
  1.23 bar. We also found this methane ice cloud to be responsible for
  the faint 'tail' seen to the feature's south and the brighter polar
  'hood' seen in all observations polewards of ∼45°N for the 5-layer
  model. <P />During the twelve days between our sets of observations
  the higher-altitude component of the feature was observed to have
  brightened significantly and extended to even higher altitudes, while
  the deeper component faded.

---------------------------------------------------------
Title: Electric Current Circuits in Astrophysics
Authors: Kuijpers, Jan; Frey, Harald U.; Fletcher, Lyndsay
2016mssf.book....3K    Altcode:
  No abstract at ADS

---------------------------------------------------------
Title: Properties of Discrete and Axisymmetric Features in Jupiter's
Atmosphere from Observations of Thermal Emission: Recent Updates on
    the Eve of the Juno Mission Arrival at Jupiter
Authors: Orton, G. S.; Fletcher, L. N.; Giles, R.; Sinclair, J.;
   Greathouse, T. K.; Momary, T.; Yanamandra-Fisher, P. A.; Fujiyoshi,
   T.; Fisher, B.; Payne, A.; Seede, R.; Simon, J.; Lai, M.; Nguyen,
   M.; Fernandez, J.; Baines, K. H.
2015AGUFM.P41B2067O    Altcode:
  We have derived the spatial distribution and evolution of key properties
  of Jupiter's atmosphere through the analysis of imaging and spatially
  resolved spectroscopy of its thermal emission. These observations
  and their analysis represent a source of data we plan to acquire
  as a key component of support for the Juno mission's atmospheric
  investigation. From thermal imaging and spectroscopy in the 7-25 µm
  region, we can derive temperatures between 10 and 500 mbar atmospheric
  pressure, cloud opacities between 500 mbar and 5 bars, the para-H2
  fraction near 300 mbar, the 100-400 mbar distributions of ammonia and
  phosphine, and the distribution of hydrocarbons in the stratosphere
  (~1 µbar - 10 mbar). Earlier work determined atmospheric properties
  of Jupiter's Great Red Spot (Fletcher et al. 2010, Icarus 208, 306)
  and the evolution of the South Equatorial Belt (SEB) fade (whitening)
  in 2009-2010 (Fletcher et al. 2011 Icarus, 213, 564). We will illustrate
  recent results from an examination of (1) the revival (re-darkening)
  of the SEB in 2010-2011, (2) discovery of uniquely dry regions of the
  atmosphere that are identified with visible "brown barges" typically
  located at the northern edge of Jupiter's North Equatorial Belt
  (NEB), (3) vertical structure of stratospheric waves constituting
  Jupiter's Quadrennial Oscillation (QQO) (Leovy et al. 1991, Nature
  354, 380), and (4) previously unsuspected long-term tropospheric
  thermal waves uncovered in our multi-year program covering well over
  a Jovian year. Efforts are underway to provide mission-supporting
  observations using mid-infrared facility and guest instruments at
  several observatories during the 14-day orbits of the Juno mission,
  particularly - but not exclusively - the early orbits dedicated to
  remote sensing observations.

---------------------------------------------------------
Title: The Europa Imaging System (EIS): High-Resolution, 3-D Insight
    into Europa's Geology, Ice Shell, and Potential for Current Activity
Authors: Turtle, E. P.; McEwen, A. S.; Collins, G. C.; Fletcher, L. N.;
   Hansen, C. J.; Hayes, A.; Hurford, T., Jr.; Kirk, R. L.; Barr, A.;
   Nimmo, F.; Patterson, G.; Quick, L. C.; Soderblom, J. M.; Thomas, N.
2015AGUFM.P13E..03T    Altcode:
  The Europa Imaging System will transform our understanding of Europa
  through global decameter-scale coverage, three-dimensional maps,
  and unprecedented meter-scale imaging. EIS combines narrow-angle and
  wide-angle cameras (NAC and WAC) designed to address high-priority
  Europa science and reconnaissance goals. It will: (A) Characterize
  the ice shell by constraining its thickness and correlating surface
  features with subsurface structures detected by ice penetrating
  radar; (B) Constrain formation processes of surface features and
  the potential for current activity by characterizing endogenic
  structures, surface units, global cross-cutting relationships, and
  relationships to Europa's subsurface structure, and by searching
  for evidence of recent activity, including potential plumes; and (C)
  Characterize scientifically compelling landing sites and hazards by
  determining the nature of the surface at scales relevant to a potential
  lander. The NAC provides very high-resolution, stereo reconnaissance,
  generating 2-km-wide swaths at 0.5-m pixel scale from 50-km altitude,
  and uses a gimbal to enable independent targeting. NAC observations
  also include: near-global (&gt;95%) mapping of Europa at ≤50-m
  pixel scale (to date, only ~14% of Europa has been imaged at ≤500
  m/pixel, with best pixel scale 6 m); regional and high-resolution
  stereo imaging at &lt;1-m/pixel; and high-phase-angle observations
  for plume searches. The WAC is designed to acquire pushbroom stereo
  swaths along flyby ground-tracks, generating digital topographic
  models with 32-m spatial scale and 4-m vertical precision from 50-km
  altitude. These data support characterization of cross-track clutter
  for radar sounding. The WAC also performs pushbroom color imaging
  with 6 broadband filters (350-1050 nm) to map surface units and
  correlations with geologic features and topography. EIS will provide
  comprehensive data sets essential to fulfilling the goal of exploring
  Europa to investigate its habitability and perform collaborative science
  with other investigations, including cartographic and geologic maps,
  regional and high-resolution digital topography, GIS products, color
  and photometric data products, a geodetic control network tied to
  radar altimetry, and a database of plume-search observations.

---------------------------------------------------------
Title: Preface
Authors: Fletcher, L.; Heinzel, P.; van Driel-Gesztelyi, L.; Mandrini,
   C. H.; Fárník, F.
2015SoPh..290.3379F    Altcode: 2015SoPh..tmp..168F
  No abstract at ADS

---------------------------------------------------------
Title: Impulsive Heating of Solar Flare Ribbons Above 10 MK
Authors: Simões, P. J. A.; Graham, D. R.; Fletcher, L.
2015SoPh..290.3573S    Altcode: 2015arXiv150503384S; 2015SoPh..tmp...62S
  The chromospheric response to the input of flare energy is marked
  by extended extreme ultraviolet (EUV) ribbons and hard X-ray (HXR)
  footpoints. These are usually explained as the result of heating and
  bremsstrahlung emission from accelerated electrons colliding in the
  dense chromospheric plasma. We present evidence of impulsive heating
  of flare ribbons above 10 MK in a two-ribbon flare. We analyse the
  impulsive phase of SOL2013-11-09T06:38, a C2.6 class event using
  data from Atmospheric Imaging Assembly (AIA) on board of the Solar
  Dynamics Observatory (SDO) and the Reuven Ramaty High Energy Solar
  Spectroscopic Imager (RHESSI) to derive the temperature, emission
  measure and differential emission measure of the flaring regions and
  investigate the evolution of the plasma in the flaring ribbons. The
  ribbons were visible at all SDO/AIA EUV/UV wavelengths, in particular,
  at 94 and 131 Å filters, sensitive to temperatures of 8 MK and 12
  MK. The time evolution of the emission measure of the plasma above 10
  MK at the ribbons has a peak near the HXR peak time. The presence of
  hot plasma in the lower atmosphere is further confirmed by a RHESSI
  imaging spectroscopy analysis, which shows resolved sources at 11 -
  13 MK that are associated with at least one ribbon. We found that
  collisional beam-heating can only marginally explain the power necessary
  to heat the 10 MK plasma at the ribbons.

---------------------------------------------------------
Title: The EChO science case
Authors: Tinetti, Giovanna; Drossart, Pierre; Eccleston, Paul; Hartogh,
   Paul; Isaak, Kate; Linder, Martin; Lovis, Christophe; Micela, Giusi;
   Ollivier, Marc; Puig, Ludovic; Ribas, Ignasi; Snellen, Ignas; Swinyard,
   Bruce; Allard, France; Barstow, Joanna; Cho, James; Coustenis, Athena;
   Cockell, Charles; Correia, Alexandre; Decin, Leen; de Kok, Remco;
   Deroo, Pieter; Encrenaz, Therese; Forget, Francois; Glasse, Alistair;
   Griffith, Caitlin; Guillot, Tristan; Koskinen, Tommi; Lammer, Helmut;
   Leconte, Jeremy; Maxted, Pierre; Mueller-Wodarg, Ingo; Nelson, Richard;
   North, Chris; Pallé, Enric; Pagano, Isabella; Piccioni, Guseppe;
   Pinfield, David; Selsis, Franck; Sozzetti, Alessandro; Stixrude,
   Lars; Tennyson, Jonathan; Turrini, Diego; Zapatero-Osorio, Mariarosa;
   Beaulieu, Jean-Philippe; Grodent, Denis; Guedel, Manuel; Luz, David;
   Nørgaard-Nielsen, Hans Ulrik; Ray, Tom; Rickman, Hans; Selig,
   Avri; Swain, Mark; Banaszkiewicz, Marek; Barlow, Mike; Bowles, Neil;
   Branduardi-Raymont, Graziella; du Foresto, Vincent Coudé; Gerard,
   Jean-Claude; Gizon, Laurent; Hornstrup, Allan; Jarchow, Christopher;
   Kerschbaum, Franz; Kovacs, Géza; Lagage, Pierre-Olivier; Lim, Tanya;
   Lopez-Morales, Mercedes; Malaguti, Giuseppe; Pace, Emanuele; Pascale,
   Enzo; Vandenbussche, Bart; Wright, Gillian; Ramos Zapata, Gonzalo;
   Adriani, Alberto; Azzollini, Ruymán; Balado, Ana; Bryson, Ian;
   Burston, Raymond; Colomé, Josep; Crook, Martin; Di Giorgio, Anna;
   Griffin, Matt; Hoogeveen, Ruud; Ottensamer, Roland; Irshad, Ranah;
   Middleton, Kevin; Morgante, Gianluca; Pinsard, Frederic; Rataj, Mirek;
   Reess, Jean-Michel; Savini, Giorgio; Schrader, Jan-Rutger; Stamper,
   Richard; Winter, Berend; Abe, L.; Abreu, M.; Achilleos, N.; Ade, P.;
   Adybekian, V.; Affer, L.; Agnor, C.; Agundez, M.; Alard, C.; Alcala,
   J.; Allende Prieto, C.; Alonso Floriano, F. J.; Altieri, F.; Alvarez
   Iglesias, C. A.; Amado, P.; Andersen, A.; Aylward, A.; Baffa, C.;
   Bakos, G.; Ballerini, P.; Banaszkiewicz, M.; Barber, R. J.; Barrado,
   D.; Barton, E. J.; Batista, V.; Bellucci, G.; Belmonte Avilés,
   J. A.; Berry, D.; Bézard, B.; Biondi, D.; Błęcka, M.; Boisse, I.;
   Bonfond, B.; Bordé, P.; Börner, P.; Bouy, H.; Brown, L.; Buchhave,
   L.; Budaj, J.; Bulgarelli, A.; Burleigh, M.; Cabral, A.; Capria,
   M. T.; Cassan, A.; Cavarroc, C.; Cecchi-Pestellini, C.; Cerulli,
   R.; Chadney, J.; Chamberlain, S.; Charnoz, S.; Christian Jessen,
   N.; Ciaravella, A.; Claret, A.; Claudi, R.; Coates, A.; Cole, R.;
   Collura, A.; Cordier, D.; Covino, E.; Danielski, C.; Damasso, M.;
   Deeg, H. J.; Delgado-Mena, E.; Del Vecchio, C.; Demangeon, O.; De Sio,
   A.; De Wit, J.; Dobrijévic, M.; Doel, P.; Dominic, C.; Dorfi, E.;
   Eales, S.; Eiroa, C.; Espinoza Contreras, M.; Esposito, M.; Eymet,
   V.; Fabrizio, N.; Fernández, M.; Femenía Castella, B.; Figueira,
   P.; Filacchione, G.; Fletcher, L.; Focardi, M.; Fossey, S.; Fouqué,
   P.; Frith, J.; Galand, M.; Gambicorti, L.; Gaulme, P.; García López,
   R. J.; Garcia-Piquer, A.; Gear, W.; Gerard, J. -C.; Gesa, L.; Giani,
   E.; Gianotti, F.; Gillon, M.; Giro, E.; Giuranna, M.; Gomez, H.;
   Gomez-Leal, I.; Gonzalez Hernandez, J.; González Merino, B.; Graczyk,
   R.; Grassi, D.; Guardia, J.; Guio, P.; Gustin, J.; Hargrave, P.; Haigh,
   J.; Hébrard, E.; Heiter, U.; Heredero, R. L.; Herrero, E.; Hersant,
   F.; Heyrovsky, D.; Hollis, M.; Hubert, B.; Hueso, R.; Israelian, G.;
   Iro, N.; Irwin, P.; Jacquemoud, S.; Jones, G.; Jones, H.; Justtanont,
   K.; Kehoe, T.; Kerschbaum, F.; Kerins, E.; Kervella, P.; Kipping, D.;
   Koskinen, T.; Krupp, N.; Lahav, O.; Laken, B.; Lanza, N.; Lellouch,
   E.; Leto, G.; Licandro Goldaracena, J.; Lithgow-Bertelloni, C.; Liu,
   S. J.; Lo Cicero, U.; Lodieu, N.; Lognonné, P.; Lopez-Puertas,
   M.; Lopez-Valverde, M. A.; Lundgaard Rasmussen, I.; Luntzer, A.;
   Machado, P.; MacTavish, C.; Maggio, A.; Maillard, J. -P.; Magnes, W.;
   Maldonado, J.; Mall, U.; Marquette, J. -B.; Mauskopf, P.; Massi, F.;
   Maurin, A. -S.; Medvedev, A.; Michaut, C.; Miles-Paez, P.; Montalto,
   M.; Montañés Rodríguez, P.; Monteiro, M.; Montes, D.; Morais, H.;
   Morales, J. C.; Morales-Calderón, M.; Morello, G.; Moro Martín,
   A.; Moses, J.; Moya Bedon, A.; Murgas Alcaino, F.; Oliva, E.; Orton,
   G.; Palla, F.; Pancrazzi, M.; Pantin, E.; Parmentier, V.; Parviainen,
   H.; Peña Ramírez, K. Y.; Peralta, J.; Perez-Hoyos, S.; Petrov, R.;
   Pezzuto, S.; Pietrzak, R.; Pilat-Lohinger, E.; Piskunov, N.; Prinja,
   R.; Prisinzano, L.; Polichtchouk, I.; Poretti, E.; Radioti, A.; Ramos,
   A. A.; Rank-Lüftinger, T.; Read, P.; Readorn, K.; Rebolo López,
   R.; Rebordão, J.; Rengel, M.; Rezac, L.; Rocchetto, M.; Rodler, F.;
   Sánchez Béjar, V. J.; Sanchez Lavega, A.; Sanromá, E.; Santos,
   N.; Sanz Forcada, J.; Scandariato, G.; Schmider, F. -X.; Scholz,
   A.; Scuderi, S.; Sethenadh, J.; Shore, S.; Showman, A.; Sicardy, B.;
   Sitek, P.; Smith, A.; Soret, L.; Sousa, S.; Stiepen, A.; Stolarski,
   M.; Strazzulla, G.; Tabernero, H. M.; Tanga, P.; Tecsa, M.; Temple,
   J.; Terenzi, L.; Tessenyi, M.; Testi, L.; Thompson, S.; Thrastarson,
   H.; Tingley, B. W.; Trifoglio, M.; Martín Torres, J.; Tozzi, A.;
   Turrini, D.; Varley, R.; Vakili, F.; de Val-Borro, M.; Valdivieso,
   M. L.; Venot, O.; Villaver, E.; Vinatier, S.; Viti, S.; Waldmann,
   I.; Waltham, D.; Ward-Thompson, D.; Waters, R.; Watkins, C.; Watson,
   D.; Wawer, P.; Wawrzaszk, A.; White, G.; Widemann, T.; Winek, W.;
   Wiśniowski, T.; Yelle, R.; Yung, Y.; Yurchenko, S. N.
2015ExA....40..329T    Altcode: 2015ExA...tmp...67T; 2015arXiv150205747T
  The discovery of almost two thousand exoplanets has revealed an
  unexpectedly diverse planet population. We see gas giants in few-day
  orbits, whole multi-planet systems within the orbit of Mercury,
  and new populations of planets with masses between that of the Earth
  and Neptune—all unknown in the Solar System. Observations to date
  have shown that our Solar System is certainly not representative of
  the general population of planets in our Milky Way. The key science
  questions that urgently need addressing are therefore: What are
  exoplanets made of? Why are planets as they are? How do planetary
  systems work and what causes the exceptional diversity observed as
  compared to the Solar System? The EChO (Exoplanet Characterisation
  Observatory) space mission was conceived to take up the challenge to
  explain this diversity in terms of formation, evolution, internal
  structure and planet and atmospheric composition. This requires
  in-depth spectroscopic knowledge of the atmospheres of a large and
  well-defined planet sample for which precise physical, chemical and
  dynamical information can be obtained. In order to fulfil this ambitious
  scientific program, EChO was designed as a dedicated survey mission
  for transit and eclipse spectroscopy capable of observing a large,
  diverse and well-defined planet sample within its 4-year mission
  lifetime. The transit and eclipse spectroscopy method, whereby the
  signal from the star and planet are differentiated using knowledge of
  the planetary ephemerides, allows us to measure atmospheric signals
  from the planet at levels of at least 10<SUP>-4</SUP> relative to
  the star. This can only be achieved in conjunction with a carefully
  designed stable payload and satellite platform. It is also necessary
  to provide broad instantaneous wavelength coverage to detect as many
  molecular species as possible, to probe the thermal structure of the
  planetary atmospheres and to correct for the contaminating effects of
  the stellar photosphere. This requires wavelength coverage of at least
  0.55 to 11 μm with a goal of covering from 0.4 to 16 μm. Only modest
  spectral resolving power is needed, with R ~ 300 for wavelengths less
  than 5 μm and R ~ 30 for wavelengths greater than this. The transit
  spectroscopy technique means that no spatial resolution is required. A
  telescope collecting area of about 1 m<SUP>2</SUP> is sufficiently
  large to achieve the necessary spectro-photometric precision: for the
  Phase A study a 1.13 m<SUP>2</SUP> telescope, diffraction limited at 3
  μm has been adopted. Placing the satellite at L2 provides a cold and
  stable thermal environment as well as a large field of regard to allow
  efficient time-critical observation of targets randomly distributed over
  the sky. EChO has been conceived to achieve a single goal: exoplanet
  spectroscopy. The spectral coverage and signal-to-noise to be achieved
  by EChO, thanks to its high stability and dedicated design, would be
  a game changer by allowing atmospheric composition to be measured
  with unparalleled exactness: at least a factor 10 more precise and
  a factor 10 to 1000 more accurate than current observations. This
  would enable the detection of molecular abundances three orders of
  magnitude lower than currently possible and a fourfold increase from
  the handful of molecules detected to date. Combining these data with
  estimates of planetary bulk compositions from accurate measurements
  of their radii and masses would allow degeneracies associated with
  planetary interior modelling to be broken, giving unique insight
  into the interior structure and elemental abundances of these alien
  worlds. EChO would allow scientists to study exoplanets both as a
  population and as individuals. The mission can target super-Earths,
  Neptune-like, and Jupiter-like planets, in the very hot to temperate
  zones (planet temperatures of 300-3000 K) of F to M-type host stars. The
  EChO core science would be delivered by a three-tier survey. The EChO
  Chemical Census: This is a broad survey of a few-hundred exoplanets,
  which allows us to explore the spectroscopic and chemical diversity of
  the exoplanet population as a whole. The EChO Origin: This is a deep
  survey of a subsample of tens of exoplanets for which significantly
  higher signal to noise and spectral resolution spectra can be obtained
  to explain the origin of the exoplanet diversity (such as formation
  mechanisms, chemical processes, atmospheric escape). The EChO Rosetta
  Stones: This is an ultra-high accuracy survey targeting a subsample
  of select exoplanets. These will be the bright "benchmark" cases
  for which a large number of measurements would be taken to explore
  temporal variations, and to obtain two and three dimensional spatial
  information on the atmospheric conditions through eclipse-mapping
  techniques. If EChO were launched today, the exoplanets currently
  observed are sufficient to provide a large and diverse sample. The
  Chemical Census survey would consist of &gt; 160 exoplanets with a range
  of planetary sizes, temperatures, orbital parameters and stellar host
  properties. Additionally, over the next 10 years, several new ground-
  and space-based transit photometric surveys and missions will come
  on-line (e.g. NGTS, CHEOPS, TESS, PLATO), which will specifically focus
  on finding bright, nearby systems. The current rapid rate of discovery
  would allow the target list to be further optimised in the years prior
  to EChO's launch and enable the atmospheric characterisation of hundreds
  of planets.

---------------------------------------------------------
Title: Determining energy balance in the flaring chromosphere from
    oxygen V line ratios
Authors: Graham, D. R.; Fletcher, L.; Labrosse, N.
2015A&A...584A...6G    Altcode: 2014arXiv1411.4603G
  Context. The impulsive phase of solar flares is a time of rapid
  energy deposition and heating in the lower solar atmosphere,
  leading to changes in the temperature and density structure of the
  region. <BR /> Aims: We use an O v density diagnostic formed from
  the λ192 /λ248 line ratio, provided by the Hinode/EIS instrument,
  to determine the density of flare footpoint plasma at O v formation
  temperatures of ~2.5 × 10<SUP>5</SUP> K, giving a constraint on the
  properties of the heated transition region. <BR /> Methods: Hinode/EIS
  rasters from 2 small flare events in December 2007 were used. Raster
  images were co-aligned to identify and establish the footpoint pixels,
  multiple-component Gaussian line fitting of the spectra was carried out
  to isolate the density diagnostic pair, and the density was calculated
  for several footpoint areas. The assumptions of equilibrium ionisation
  and optically-thin radiation for the O v lines used were assessed
  and found to be acceptable. For one of the events, properties of the
  electron distribution were deduced from earlier RHESSI hard X-ray
  observations. These were used to calculate the plasma heating rate
  delivered by an electron beam for 2 semi-empirical atmospheres under
  collisional thick-target assumptions. The radiative loss rate for
  this plasma was also calculated for comparison with possible energy
  input mechanisms. <BR /> Results: Electron number densities of up
  to 10<SUP>11.9</SUP> cm<SUP>-3</SUP> were measured during the flare
  impulsive phase using the O v λ192 /λ248 diagnostic ratio. The heating
  rate delivered by an electron beam was found to exceed the radiative
  losses at this density, corresponding to a height of 450 km, and when
  assuming a completely ionised target atmosphere far exceed the losses
  but at a height of 1450-1600 km. A chromospheric thickness of 70-700
  km was found to be required to balance a conductive input to the O
  v-emitting region with radiative losses. <BR /> Conclusions: Electron
  densities have been observed in footpoint sources at transition region
  temperatures, comparable to previous results but with improved spatial
  information. The observed densities can be explained by heating of
  the chromosphere by collisional electrons, with O v formed at heights
  of 450-1600 km above the photosphere, depending on the atmospheric
  ionisation fraction.

---------------------------------------------------------
Title: Photochemistry in Saturn's Ring-Shadowed Atmosphere: Modulation
    of Hydrocarbons and Observations of Dust Content
Authors: Edgington, S. G.; Atreya, S. K.; Wilson, E. H.; Baines,
   K. H.; West, R. A.; Bjoraker, G. L.; Fletcher, L. N.; Momary, T.
2015AGUFM.P41B2056E    Altcode:
  Cassini has been orbiting Saturn for over eleven years now. During this
  epoch, the ring shadow has moved from covering much of the northern
  hemisphere (the solar inclination was 24 degrees) to covering a large
  swath south of the equator and it continues to move southward. At
  Saturn Orbit Insertion in 2004, the projection of the A-ring onto
  Saturn reached as far as 40N along the central meridian (52N at the
  terminator). At its maximum extent, the ring shadow can reach as
  far as 48N/S (58N/S at the terminator). The net effect is that the
  intensity of both ultraviolet and visible sunlight penetrating through
  the rings to any particular latitude will vary depending on both
  Saturn's axis relative to the Sun and the optical thickness of each
  ring system. In essence, the rings act like semi-transparent venetian
  blinds. Our previous work examined the variation of the solar flux
  as a function of solar inclination, i.e. for each 7.25-year season at
  Saturn. Here, we report on the impact of the oscillating ring shadow
  on the photolysis and production rates of hydrocarbons (acetylene,
  ethane, propane, and benzene) and phosphine in Saturn's stratosphere
  and upper troposphere. The impact of these production and loss rates
  on the abundance of long-lived photochemical products leading to
  haze formation are explored. Similarly, we assess their impact on
  phosphine abundance, a disequilibrium species whose presence in the
  upper troposphere can be used as a tracer of convective processes in
  the deeper atmosphere. We will also present our ongoing analysis of
  Cassini's CIRS, UVIS, and VIMS datasets that provide an estimate of the
  evolving haze content of the northern hemisphere and we will begin to
  assess the implications for dynamical mixing. In particular, we will
  examine how the now famous hexagonal jet stream acts like a barrier to
  transport, isolating Saturn's north polar region from outside transport
  of photochemically-generated molecules and haze. The research described
  in this paper was carried out in part at the Jet Propulsion Laboratory,
  California Institute of Technology, under a contract with the National
  Aeronautics and Space Administration. Copyright 2015 California
  Institute of Technology. Government sponsorship is acknowledged.

---------------------------------------------------------
Title: The Long wave (11-16 μm) spectrograph for the EChO M3 Mission
    Candidate study
Authors: Bowles, N. E.; Tecza, M.; Barstow, J. K.; Temple, J. M.;
   Irwin, P. G. J.; Fletcher, L. N.; Calcutt, S.; Hurley, J.; Ferlet,
   M.; Freeman, D.
2015ExA....40..801B    Altcode: 2015ExA...tmp...58B
  The results for the design study of the Long Wave Infrared Module
  (LWIR), a goal spectroscopic channel for the EChO ESA medium class
  candidate mission, are presented. The requirements for the LWIR
  module were to provide coverage of the 11-16 μm spectral range at a
  moderate resolving power of at least R = 30, whilst minimising noise
  contributions above photon due to the thermal background of the EChO
  instrument and telescope, and astrophysical sources such as the zodiacal
  light. The study output module design is a KRS-6 prism spectrograph
  with aluminium mirror beam expander and coated germanium lenses
  for the final focusing elements. Thermal background considerations
  led to enclosing the beam in a baffle cooled to approximately 25-29
  K. To minimise diffuse astrophysical background contributions due to
  the zodiacal light, anamorphic designs were considered in addition
  to the elliptical input beam provided by the EChO telescope. Given
  the requirement that measurements in this waveband place on the
  performance of the infrared detector array, an additional study on
  the likely scientific return with lower resolving power ( R &lt; 30)
  is included. If specific high priority molecules on moderately warm
  giant planets (e.g. CO<SUB>2</SUB>, H<SUB>2</SUB>O) are targeted,
  the LWIR channel can still provide improvements in determining the
  atmospheric temperature structure and molecular abundances. Thus,
  the inclusion of even a coarse-resolution (R≈10) LWIR module would
  still make an important contribution to measurements of exoplanet
  atmospheres made by EChO.

---------------------------------------------------------
Title: Soft X-Ray Pulsations in Solar Flares
Authors: Simões, P. J. A.; Hudson, H. S.; Fletcher, L.
2015SoPh..290.3625S    Altcode: 2014arXiv1412.3045S; 2015SoPh..tmp...50S
  The soft X-ray emissions (hν&gt;1.5 keV) of solar flares mainly come
  from the bright coronal loops at the highest temperatures normally
  achieved in the flare process. Their ubiquity has led to their use
  as a standard measure of flare occurrence and energy, although the
  overwhelming bulk of the total flare energy goes elsewhere. Recently
  Dolla et al. (Astrophys. J. Lett.749, L16, 2012) noted quasi-periodic
  pulsations (QPP) in the soft X-ray signature of the X-class flare
  SOL2011-02-15, as observed by the standard photometric data from the
  GOES (Geostationary Operational Environmental Satellite) spacecraft. In
  this article we analyse the suitability of the GOES data for this type
  of analysis and find them to be generally valuable after September,
  2010 (GOES-15). We then extend the result of Dolla et al. to a complete
  list of X-class flares from Cycle 24 and show that most of them (80 %)
  display QPPs in the impulsive phase. The pulsations show up cleanly in
  both channels of the GOES data, making use of time-series of irradiance
  differences (the digital time derivative on the 2-s sampling). We deploy
  different techniques to characterise the periodicity of GOES pulsations,
  considering the red-noise properties of the flare signals, finding
  a range of characteristic time scales of the QPPs for each event,
  but usually with no strong signature of a single period dominating
  in the power spectrum. The QPP may also appear on somewhat longer
  time scales during the later gradual phase, possibly with a greater
  tendency towards coherence, but the sampling noise in GOES difference
  data for high irradiance values (X-class flares) makes these more
  uncertain. We show that there is minimal phase difference between
  the differenced GOES energy channels, or between them and the hard
  X-ray variations on short time scales. During the impulsive phase,
  the footpoints of the newly forming flare loops may also contribute
  to the observed soft X-ray variations.

---------------------------------------------------------
Title: Hα Line Profile Asymmetries and the Chromospheric Flare
    Velocity Field
Authors: Kuridze, D.; Mathioudakis, M.; Simões, P. J. A.; Rouppe van
   der Voort, L.; Carlsson, M.; Jafarzadeh, S.; Allred, J. C.; Kowalski,
   A. F.; Kennedy, M.; Fletcher, L.; Graham, D.; Keenan, F. P.
2015ApJ...813..125K    Altcode: 2015arXiv151001877K
  The asymmetries observed in the line profiles of solar flares can
  provide important diagnostics of the properties and dynamics of the
  flaring atmosphere. In this paper the evolution of the Hα and Ca ii
  λ8542 lines are studied using high spatial, temporal, and spectral
  resolution ground-based observations of an M1.1 flare obtained with
  the Swedish 1 m Solar Telescope. The temporal evolution of the Hα
  line profiles from the flare kernel shows excess emission in the red
  wing (red asymmetry) before flare maximum and excess in the blue wing
  (blue asymmetry) after maximum. However, the Ca ii λ8542 line does
  not follow the same pattern, showing only a weak red asymmetry during
  the flare. RADYN simulations are used to synthesize spectral line
  profiles for the flaring atmosphere, and good agreement is found
  with the observations. We show that the red asymmetry observed in
  Hα is not necessarily associated with plasma downflows, and the blue
  asymmetry may not be related to plasma upflows. Indeed, we conclude
  that the steep velocity gradients in the flaring chromosphere modify
  the wavelength of the central reversal in the Hα line profile. The
  shift in the wavelength of maximum opacity to shorter and longer
  wavelengths generates the red and blue asymmetries, respectively.

---------------------------------------------------------
Title: Photochemistry in Saturn's Ring-Shadowed Atmosphere:
    Hydrocarbon Modulation &amp; Observations of Dust Content
Authors: Edgington, S. G.; Atreya, S. K.; Wilson, E. H.; West, R. A.;
   Bjoraker, G. L.; Fletcher, L. N.; Baines, K. H.; Momary, T.
2015EPSC...10..399E    Altcode:
  Cassini has been orbiting Saturn for eleven years. During this epoch,
  the ring shadow has moved from covering a relatively large portion of
  the northern hemisphere (Figure 1) to covering a large swath south of
  the equator and continues to move southward. At Saturn Orbit Insertion
  on July 1, 2004, the ring plane was inclined by ~24 degrees relative
  to the Sun -Saturn vector. At this time, the projection of the B-ring
  onto Saturn reached as far as 40ºN along the central meridian (~52ºN
  at the terminator). At its maximum extent, the ring shadow can reach
  as far as 48ºN (~58ºN at the terminator). The net effect is that the
  intensity of both ultraviolet and visible sunlight penetrating into any
  particular latitude will vary depending on both Saturn's axis relative
  to the Sun and the optical thickness of each ring system. In essence,
  the rings act like venetian blinds.

---------------------------------------------------------
Title: A solar tornado observed by EIS. Plasma diagnostics
Authors: Levens, P. J.; Labrosse, N.; Fletcher, L.; Schmieder, B.
2015A&A...582A..27L    Altcode: 2015arXiv150801377L
  Context. The term "solar tornadoes" has been used to describe apparently
  rotating magnetic structures above the solar limb, as seen in high
  resolution images and movies from the Atmospheric Imaging Assembly
  (AIA) aboard the Solar Dynamics Observatory (SDO). These often form
  part of the larger magnetic structure of a prominence, however the
  links between them remain unclear. Here we present plasma diagnostics
  on a tornado-like structure and its surroundings, seen above the
  limb by the Extreme-ultraviolet Imaging Spectrometer (EIS) aboard
  the Hinode satellite. <BR /> Aims: We aim to extend our view of the
  velocity patterns seen in tornado-like structures with EIS to a wider
  range of temperatures and to use density diagnostics, non-thermal
  line widths, and differential emission measures to provide insight
  into the physical characteristics of the plasma. <BR /> Methods:
  Using Gaussian fitting to fit and de-blend the spectral lines seen
  by EIS, we calculated line-of-sight velocities and non-thermal line
  widths. Along with information from the CHIANTI database, we used line
  intensity ratios to calculate electron densities at each pixel. Using
  a regularised inversion code we also calculated the differential
  emission measure (DEM) at different locations in the prominence. <BR
  /> Results: The split Doppler-shift pattern is found to be visible
  down to a temperature of around log T = 6.0. At temperatures lower
  than this, the pattern is unclear in this data set. We obtain an
  electron density of log n<SUB>e</SUB> = 8.5 when looking towards the
  centre of the tornado structure at a plasma temperature of log T =
  6.2, as compared to the surroundings of the tornado structure where
  we find log n<SUB>e</SUB> to be nearer 9. Non-thermal line widths
  show broader profiles at the tornado location when compared to the
  surrounding corona. We discuss the differential emission measure in
  both the tornado and the prominence body, which suggests that there is
  more contribution in the tornado at temperatures below log T = 6.0 than
  in the prominence. <P />A movie is available in electronic form at <A
  href="http://www.aanda.org/10.1051/0004-6361/201425586/olm">http://www.aanda.org</A>

---------------------------------------------------------
Title: IRIS observations of the Mg ii h and k lines during a solar
    flare
Authors: Kerr, G. S.; Simões, P. J. A.; Qiu, J.; Fletcher, L.
2015A&A...582A..50K    Altcode: 2015arXiv150803813K
  The bulk of the radiative output of a solar flare is emitted from
  the chromosphere, which produces enhancements in the optical and UV
  continuum, and in many lines, both optically thick and thin. We have,
  until very recently, lacked observations of two of the strongest of
  these lines: the Mg ii h and k resonance lines. We present a detailed
  study of the response of these lines to a solar flare. The spatial and
  temporal behaviour of the integrated intensities, k/h line ratios,
  line of sight velocities, line widths and line asymmetries were
  investigated during an M class flare (SOL2014-02-13T01:40). Very
  intense, spatially localised energy input at the outer edge of the
  ribbon is observed, resulting in redshifts equivalent to velocities of
  ~15-26 km s<SUP>-1</SUP>, line broadenings, and a blue asymmetry in the
  most intense sources. The characteristic central reversal feature that
  is ubiquitous in quiet Sun observations is absent in flaring profiles,
  indicating that the source function increases with height during the
  flare. Despite the absence of the central reversal feature, the k/h
  line ratio indicates that the lines remain optically thick during
  the flare. Subordinate lines in the Mg ii passband are observed to be
  in emission in flaring sources, brightening and cooling with similar
  timescales to the resonance lines. This work represents a first analysis
  of potential diagnostic information of the flaring atmosphere using
  these lines, and provides observations to which synthetic spectra from
  advanced radiative transfer codes can be compared.

---------------------------------------------------------
Title: Observations of Jupiter at 5 micron from IRTF/TEXES :
    latitudinal variability of disequilibrium species
Authors: Drossart, P.; Encrenaz, T.; Greathouse, T. K.; DeWitt, C.;
   Fouchet, T.; Janssen, M.; Gulkis, S.; Orton, G. S.; Fletcher, L.;
   Giles, R.; Atreya, S. K.; Boudon, V.
2015EPSC...10..194D    Altcode:
  Observations of Jupiter in the 5 μm spectral window,obtained in
  March/April 2015 at IRTF are presented, in preparation of the arrival of
  the NASA/JUNO mission in 2016. Sounding of the troposphere of Jupiter
  below 2 bars is obtained from the observations, to search for the
  variability of disequilibrium species, related to deep atmospheric
  circulation.

---------------------------------------------------------
Title: Stratospheric temperature and composition of Jupiter's polar
    aurora from IRTF-TEXES
Authors: Sinclair, J.; Orton, G. S.; Greathouse, T. K.; Fletcher,
   L. N.; Irwin, P. G. J.
2015EPSC...10..374S    Altcode:
  We perform an analysis of TEXES (Texas Echelon Cross Echelle
  Spectrograph, 5- to 25- μm,[1]) spectra of Jupiter's high latitudes
  observed in December 2014 in order to study the jovian polar
  aurora. The high resolving power (R∼85000) of TEXES allows a large
  altitude range (10 mbar to 0.01 mbar) in Jupiter's stratosphere to
  be sounded. Retrievals of temperature and stratospheric composition
  of these measurements therefore: 1) allow the vertical deposition
  of auroral energy to be determined and 2) quantify how the auro-ral
  processes modify the thermal structure and composition of the jovian
  stratosphere.

---------------------------------------------------------
Title: JUICE: A European Mission to Jupiter and its Icy Moons
Authors: Witasse, O.; Altobelli, N.; Barabash, S.; Bruzzone, L.;
   Dougherty, M.; Erd, C.; Fletcher, L.; Gladstone, R.; Grasset, O.;
   Gurvits, L.; Hartogh, P.; Hussmann, H.; Iess, I.; Langevin, Y.;
   Palumbo, P.; Piccioni, G.; Sarri, G.; Titov, D.; Wahlund, J. -E.
2015EPSC...10..564W    Altcode:
  JUICE -JUpiter ICy moons Explorer -is the first large mission in the
  ESA Cosmic Vision 2015-2025 programme[1]. The mission was selected
  in May 2012 and adopted in November 2014. The implementation phase
  starts in July 2015, following the selection of the prime industrial
  contractor. Planned for launch in June 2022 and arrival at Jupiter
  in October 2029, it will spend at least three years making detailed
  observations of Jupiter and three of its largest moons, Ganymede,
  Callisto and Europa.

---------------------------------------------------------
Title: A unified view of coronal loop contraction and oscillation
    in flares
Authors: Russell, A. J. B.; Simões, P. J. A.; Fletcher, L.
2015A&A...581A...8R    Altcode: 2015arXiv150607716R
  Context. Transverse loop oscillations and loop contractions are
  commonly associated with solar flares, but the two types of motion
  have traditionally been regarded as separate phenomena. <BR /> Aims:
  We present an observation of coronal loops that contract and oscillate
  following the onset of a flare. We aim to explain why both behaviours
  are seen together and why only some of the loops oscillate. <BR />
  Methods: A time sequence of SDO/AIA 171 Å images is analysed to
  identify the positions of coronal loops following the onset of the
  M6.4 flare SOL2012-03-09T03:53. We focus on five loops in particular,
  all of which contract during the flare, with three of them oscillating
  as well. A simple model is then developed for the contraction and
  oscillation of a coronal loop. <BR /> Results: We propose that coronal
  loop contractions and oscillations can occur in a single response to
  removal of magnetic energy from the corona. Our model reproduces the
  various types of loop motion observed and explains why the highest loops
  oscillate during their contraction, while no oscillation is detected for
  the shortest contracting loops. The proposed framework suggests that
  loop motions can be used as a diagnostic for the removal of coronal
  magnetic energy by flares, while rapid decrease in coronal magnetic
  energy is a newly identified excitation mechanism for transverse loop
  oscillations. <P />Appendices are available in electronic form at <A
  href="http://www.aanda.org/10.1051/0004-6361/201525746/olm">http://www.aanda.org</A>

---------------------------------------------------------
Title: Cloud structure and composition of Jupiter's troposphere from
    5- μ m Cassini VIMS spectroscopy
Authors: Giles, R. S.; Fletcher, L. N.; Irwin, P. G. J.
2015Icar..257..457G    Altcode: 2015arXiv150601608G
  Jupiter's tropospheric composition and cloud structure are studied
  using Cassini VIMS 4.5-5.1 μ m thermal emission spectra from
  the 2000-2001 flyby. We make use of both nadir and limb darkening
  observations on the planet's nightside, and compare these with dayside
  observations. Although there is significant spatial variability
  in the 5- μ m brightness temperatures, the shape of the spectra
  remain very similar across the planet, suggesting the presence of a
  spectrally-flat, spatially inhomogeneous cloud deck. We find that a
  simple cloud model consisting of a single, compact cloud is able to
  reproduce both nightside and dayside spectra, subject to the following
  constraints: (i) the cloud base is located at pressures of 1.2 bar
  or lower; (ii) the cloud particles are highly scattering; and (iii)
  the cloud is sufficiently spectrally flat. Using this cloud model, we
  search for global variability in the cloud opacity and the phosphine
  deep volume mixing ratio. We find that the vast majority of the 5- μ
  m inhomogeneity can be accounted for by variations in the thickness
  of the cloud decks, with huge differences between the cloudy zones
  and the relatively cloud-free belts. The relatively low spectral
  resolution of VIMS limits reliable retrievals of gaseous species,
  but some evidence is found for an enhancement in the abundance of
  phosphine at high latitudes.

---------------------------------------------------------
Title: Photochemical response to the variation of temperature in
    the 2011-2012 stratospheric vortex of Saturn
Authors: Cavalié, T.; Dobrijevic, M.; Fletcher, L. N.; Loison,
   J. -C.; Hickson, K. M.; Hue, V.; Hartogh, P.
2015A&A...580A..55C    Altcode:
  Context. A hot vortex formed in the stratosphere of Saturn following
  the 2010-2011 Northern Storm. Huge temperature increases have been
  measured in the vortex around the millibar level. Enhancements in
  hydrocarbon abundances have been observed at the millibar level in
  2011-2012 inside this vortex. <BR /> Aims: We model the time-dependent
  photochemistry inside the vortex by accounting for the temperature
  variability over the period from January 2011 to March 2012 to assess
  whether photochemistry alone can explain the enhancements seen in the
  hydrocarbon abundances. <BR /> Methods: We used a 1D time-dependent
  photochemical model of Saturn and adapted it to the perturbed conditions
  of the vortex after validating it in quiescent conditions. <BR
  /> Results: Our model predicts non-variability for ethane
  (C<SUB>2</SUB>H<SUB>6</SUB>) and acetylene (C<SUB>2</SUB>H<SUB>2</SUB>)
  and an increase in ethylene (C<SUB>2</SUB>H<SUB>4</SUB>) by a factor of
  3 in the mbar region. Heavier hydrocarbons show a stronger variability
  than the lighter ones. We are unable to reproduce the increase seen
  in C<SUB>2</SUB>H<SUB>2</SUB> , and we significantly underestimate the
  increase seen in C<SUB>2</SUB>H<SUB>4</SUB>. <BR /> Conclusions: Pure
  photochemistry does not explain the variability seen in the abundance
  of most hydrocarbons. This means that dynamics (eddy diffusion and/or
  advection) must have played a significant role in shaping the vertical
  profiles of the main hydrocarbons.

---------------------------------------------------------
Title: Erratum: Transit spectroscopy with JWST: systematics,
    star-spots and stitching
Authors: Barstow, J. K.; Aigrain, S.; Irwin, P. G. J.; Kendrew, S.;
   Fletcher, L. N.
2015MNRAS.451.1306B    Altcode:
  No abstract at ADS

---------------------------------------------------------
Title: Division II: Commission 10: Solar Activity
Authors: van Driel-Gesztelyi, Lidia; Scrijver, Karel J.; Klimchuk,
   James A.; Charbonneau, Paul; Fletcher, Lyndsay; Hasan, S. Sirajul;
   Hudson, Hugh S.; Kusano, Kanya; Mandrini, Cristina H.; Peter, Hardi;
   Vršnak, Bojan; Yan, Yihua
2015IAUTB..28..106V    Altcode:
  The Business Meeting of Commission 10 was held as part of the Business
  Meeting of Division II (Sun and Heliosphere), chaired by Valentin
  Martínez-Pillet, the President of the Division. The President of
  Commission 10 (C10; Solar activity), Lidia van Driel-Gesztelyi, took
  the chair for the business meeting of C10. She summarised the activities
  of C10 over the triennium and the election of the incoming OC.

---------------------------------------------------------
Title: Solar Flares and the Chromosphere
Authors: Fletcher, Lyndsay
2015IAUGA..2286134F    Altcode:
  During a solar flare, the chromosphere emits across a large fraction
  of the electromagnetic spectrum, providing diagnostic information
  on heating, dynamics and flare energy transport by both thermal and
  non-thermal means. The evolution of chromospheric ribbons and footpoints
  also traces the progress of coronal reconnection, and links radiation
  output with magnetic evolution. Since the chromosphere emits the
  majority of a flare's radiation, the current emphasis on chromospheric
  observations by missions such as IRIS, and future large facilities
  such as the DKIST, is very beneficial to flare research. In this
  talk I will overview recent developments in observations and theory
  of flaring chromospheres and make some suggestions about profitable
  future avenues for research.

---------------------------------------------------------
Title: Meandering Shallow Atmospheric Jet as a Model of Saturn's
    North-polar Hexagon
Authors: Morales-Juberías, R.; Sayanagi, K. M.; Simon, A. A.;
   Fletcher, L. N.; Cosentino, R. G.
2015ApJ...806L..18M    Altcode:
  The Voyager flybys of Saturn in 1980-1981 revealed a circumpolar
  Hexagon at ∼78° north planetographic latitude that has persisted
  for over 30 Earth years, more than one Saturn year, and has been
  observed by ground-based telescopes, Hubble Space Telescope and
  multiple instruments on board the Cassini orbiter. Its average phase
  speed is very slow with respect to the System III rotation rate,
  defined by the primary periodicity in the Saturn Kilometric Radiation
  during the Voyager era. Cloud tracking wind measurements reveal the
  presence of a prograde jet-stream whose path traces the Hexagon’s
  shape. Previous numerical models have produced large-amplitude, n = 6,
  wavy structures with westward intrinsic phase propagation (relative to
  the jet). However, the observed net phase speed has proven to be more
  difficult to achieve. Here we present numerical simulations showing
  that instabilities in shallow jets can equilibrate as meanders closely
  resembling the observed morphology and phase speed of Saturn’s
  northern Hexagon. We also find that the winds at the bottom of the
  model are as important as the winds at the cloud level in matching
  the observed Hexagon’s characteristics.

---------------------------------------------------------
Title: Structures in the Outer Solar Atmosphere
Authors: Fletcher, L.; Cargill, P. J.; Antiochos, S. K.; Gudiksen,
   B. V.
2015SSRv..188..211F    Altcode: 2014SSRv..tmp...52F; 2014arXiv1412.7378F
  The structure and dynamics of the outer solar atmosphere are reviewed
  with emphasis on the role played by the magnetic field. Contemporary
  observations that focus on high resolution imaging over a range
  of temperatures, as well as UV, EUV and hard X-ray spectroscopy,
  demonstrate the presence of a vast range of temporal and spatial scales,
  mass motions, and particle energies present. By focusing on recent
  developments in the chromosphere, corona and solar wind, it is shown
  that small scale processes, in particular magnetic reconnection, play
  a central role in determining the large-scale structure and properties
  of all regions. This coupling of scales is central to understanding
  the atmosphere, yet poses formidable challenges for theoretical models.

---------------------------------------------------------
Title: VizieR Online Data Catalog: Bayesian method for detecting
    stellar flares (Pitkin+, 2014)
Authors: Pitkin, M.; Williams, D.; Fletcher, L.; Grant, S. D. T.
2015yCat..74452268P    Altcode:
  We present a Bayesian-odds-ratio-based algorithm for detecting stellar
  flares in light-curve data. We assume flares are described by a
  model in which there is a rapid rise with a half-Gaussian profile,
  followed by an exponential decay. Our signal model also contains a
  polynomial background model required to fit underlying light-curve
  variations in the data, which could otherwise partially mimic a
  flare. We characterize the false alarm probability and efficiency of
  this method under the assumption that any unmodelled noise in the data
  is Gaussian, and compare it with a simpler thresholding method based
  on that used in Walkowicz et al. We find our method has a significant
  increase in detection efficiency for low signal-to-noise ratio (S/N)
  flares. For a conservative false alarm probability our method can
  detect 95 per cent of flares with S/N less than 20, as compared to S/N
  of 25 for the simpler method. We also test how well the assumption of
  Gaussian noise holds by applying the method to a selection of 'quiet'
  Kepler stars. As an example we have applied our method to a selection
  of stars in Kepler Quarter 1 data. The method finds 687 flaring stars
  with a total of 1873 flares after vetos have been applied. For these
  flares we have made preliminary characterizations of their durations
  and and S/N. <P />(1 data file).

---------------------------------------------------------
Title: Direct observation of the energy release site in a solar
    flare by SDO/AIA, Hinode/EIS, and RHESSI
Authors: Simões, P. J. A.; Graham, D. R.; Fletcher, L.
2015A&A...577A..68S    Altcode: 2015arXiv150301491S
  <BR /> Aims: We present direct evidence of the detection of the main
  energy release site in a non-eruptive solar flare, SOL2013-11-09T06:38
  UT. This GOES class C2.6 event was characterised by two flaring ribbons
  and a compact, bright coronal source located between them, which is
  the focus of our study. <BR /> Methods: We use imaging from SDO/AIA,
  and imaging spectroscopy from RHESSI to characterise the thermal and
  non-thermal emission from the coronal source, and EUV spectroscopy
  from the Hinode/Extreme ultraviolet Imaging Spectrometer, which
  scanned the coronal source during the impulsive peak, to analyse
  Doppler shifts in Fe xii (log T = 6.2) and Fe xxiv (log T = 7.2)
  emission lines, and determine the source density. <BR /> Results:
  The coronal source exhibited an impulsive emission lightcurve in all
  SDO/AIA filters during the impulsive phase. RHESSI hard X-ray images
  indicate both thermal and non-thermal emission at the coronal source,
  and its plasma temperature derived from RHESSI imaging spectroscopy
  shows an impulsive rise, reaching a maximum at 12-13 MK about 10 s
  prior to the hard X-ray peak. High red-shifts associated with this
  bright source indicate downflows of 40-250 km s<SUP>-1</SUP> at a broad
  range of temperatures, interpreted as loop shrinkage and/or outflows
  along the magnetic field. Outflows from the coronal source towards
  each ribbon are also observed by SDO/AIA images at 171, 193, 211, 304,
  and 1600 Å. The electron density of the source obtained from a Fe xiv
  line pair is 10<SUP>11.50</SUP> cm<SUP>-3</SUP> which is collisionally
  thick to electrons with energy up to 45-65 keV, responsible for the
  source's non-thermal X-ray emission. <BR /> Conclusions: Given the
  rich observational evidence, we conclude that the bright coronal source
  is the location of the main release of magnetic energy in this flare,
  with a geometry consistent with component reconnection between crossing,
  current-carrying loops. We argue that the energy that can be released
  via reconnection, based on observational estimates, can plausibly
  account for the non-thermal energetics of the flare.

---------------------------------------------------------
Title: Electric Current Circuits in Astrophysics
Authors: Kuijpers, Jan; Frey, Harald U.; Fletcher, Lyndsay
2015SSRv..188....3K    Altcode: 2014arXiv1403.0795K; 2014SSRv..tmp...19K
  Cosmic magnetic structures have in common that they are anchored in a
  dynamo, that an external driver converts kinetic energy into internal
  magnetic energy, that this magnetic energy is transported as Poynting
  flux across the magnetically dominated structure, and that the magnetic
  energy is released in the form of particle acceleration, heating, bulk
  motion, MHD waves, and radiation. The investigation of the electric
  current system is particularly illuminating as to the course of events
  and the physics involved. We demonstrate this for the radio pulsar wind,
  the solar flare, and terrestrial magnetic storms.

---------------------------------------------------------
Title: Reanalysis of Uranus' cloud scattering properties from
    IRTF/SpeX observations using a self-consistent scattering cloud
    retrieval scheme
Authors: Irwin, P. G. J.; Tice, D. S.; Fletcher, L. N.; Barstow,
   J. K.; Teanby, N. A.; Orton, G. S.; Davis, G. R.
2015Icar..250..462I    Altcode: 2016arXiv160102814I
  We have developed a new retrieval approach to modelling near-infrared
  spectra of Uranus that represents a significant improvement over
  previous modelling methods. We reanalysed IRTF/SpeX observations of
  Uranus observed in 2009 covering the wavelength range 0.8-1.8 μm and
  reported by Tice et al. (Tice, D.S., Irwin, P.G.J., Fletcher, L.N.,
  Teanby, N.A., Hurley, J., Orton, G.S., Davis, G.R. [2013]. Icarus
  223, 684-698). By retrieving the imaginary refractive index spectra
  of cloud particles we are able to consistently define the real part
  of the refractive index spectra, through a Kramers-Kronig analysis,
  and thus determine self-consistent extinction cross-section,
  single-scattering and phase-function spectra for the clouds and
  hazes in Uranus' atmosphere. We tested two different cloud-modelling
  schemes used in conjunction with the temperature/methane profile of
  Baines et al. (Baines, K.H., Mickelson, M.E., Larson, L.E., Ferguson,
  D.W. [1995]. Icarus 114, 328-340), a reanalysis of the Voyager-2
  radio-occultation observations performed by Sromovsky, Fry and Kim
  (Sromovsky, L.A., Fry, P.M., Kim, J.H. [2011]. Icarus 215, 292-312),
  and a recent determination from Spitzer (Orton, G.S., Fletcher, L.N.,
  Moses, J.I., Mainzer, A.K., Hines, D., Hammel, H.B., Martin-Torres,
  F.J., Burgdorf, M., Merlet, C., Line, M.R. [2014]. Icarus 243,
  494-513). We find that both cloud-modelling schemes represent the
  observed centre-of-disc spectrum of Uranus well, and both require
  similar cloud scattering properties of the main cloud residing at ∼2
  bars. However, a modified version of the Sromovsky, Fry and Kim (2011)
  model, with revised spectral properties of the lowest cloud layer,
  fits slightly better at shorter wavelengths and is more consistent
  with the expected vertical position of Uranus' methane cloud. <P />We
  find that the bulk of the reflected radiance from Uranus arises from
  a thick cloud at approximately the 2 bar level, composed of particles
  that are significantly more absorbing at wavelengths λ &gt; 1.0 μm
  than they are at shorter wavelengths λ &lt; 1.0 μm. This spectral
  information provides a possible constraint on the identity of the
  main particle type, although we find that the scattering properties
  required are not consistent with any of the available laboratory data
  for pure NH<SUB>3</SUB>, NH<SUB>4</SUB>SH, or CH<SUB>4</SUB> ice (all
  suspected of condensing in the upper troposphere). It is possible that
  the observed clouds are mixtures of tropospheric condensate mixed with
  photochemical products diffusing down from above, which masks their
  pure scattering features. Because there is no available laboratory
  data for pure H<SUB>2</SUB>S or PH<SUB>3</SUB> ice (both of which
  might be present as well), they cannot be excluded as the cloud-forming
  species. We note, however, that their absorptive properties would have
  to be two orders of magnitude greater than the other measured ices at
  wavelengths greater than 1 μm to be consistent with our retrieval,
  which suggests that mixing with photochemical products may still
  be important.

---------------------------------------------------------
Title: IRIS Observations of the Mg II h &amp; k Lines During a
    Solar Flare
Authors: Kerr, Graham Stewart; Simões, Paulo J. A.; Qiu, Jiong;
   Fletcher, Lyndsay
2015TESS....130702K    Altcode:
  The bulk of the radiative output of a solar flare is radiated from the
  chromosphere. We have, until very recently, lacked routine observations
  of one of the strongest chromospheric lines: the MgII h&amp;k resonance
  lines. These optically thick lines sample the atmosphere from the
  upper photosphere to the upper chromosphere and have been shown to be
  important diagnostics of the atmosphere in the non flaring features
  (quiet Sun, plage, network, sunspots, and prominences). However,
  only one flare observation of these lines has been reported (Lemaire
  et al 1984). With the launch of the IRIS solar telescope we are in a
  position to routinely observe the MgII h&amp;k lines during flares,
  and we present a detailed study of the response of these lines to
  a solar flare. The spatial and temporal behaviour of the integrated
  intensities, k/h line ratios, line of sight velocities, line widths
  and line asymmetries were investigated during an M class flare, using
  a nonparametric quartiles approach. Redshifts of ~20km/s and line
  broadenings are observed at times of significant intensity enhancements,
  at the outer edge of the flare ribbons. The lines show blue asymmetry
  in only the most intense sources. Interestingly the characteristic
  central reversal feature that is ubiquitous in quiet Sun observations
  is absent in flaring profiles. Subordinate lines in the MgII passband
  are observed to be in emission within flaring sources, brightening and
  cooling in sync with the resonance lines. Additionally, we present the
  results of initial experiments with advanced numerical models to aid
  in the physical interpretation of these observed properties. This was
  achieved using the radiation hydrodynamic code RADYN that simulates
  the response of the solar atmosphere to flare energy input (we used
  a range of beam parameters to investigate energy injection to the
  atmosphere). RADYN provides both the hydrodynamic response of the
  atmosphere and the radiative response in energetically important lines
  and continua. The hydrodynamic output from RADYN was used as input to
  the radiative transfer code RH that solves the MgII resonance lines
  using partial redistributon.

---------------------------------------------------------
Title: The Radiated Energy Budget Of Chromospheric Plasma In A Major
    Solar Flare Deduced From Multi-Wavelength Observations
Authors: Milligan, Ryan; Kerr, Graham Stewart; Dennis, Brian; Hudson,
   Hugh; Fletcher, Lyndsay; Allred, Joel; Chamberlin, Phillip; Ireland,
   Jack; Mathioudakis, Mihalis; Keenan, Francis
2015TESS....130209M    Altcode:
  The response of the lower solar atmosphere is an important diagnostic
  tool for understanding energy transport during solar flares. The 15
  February 2011 X-class flare was fortuitously observed by a host of
  space-based instruments that sampled the chromospheric response over
  a range of lines and continua at &lt;20s cadence. These include the
  free-bound EUV continua of H I (Lyman), He I, and He II, plus the
  emission lines of He II at 304Å and H I (Lyα) at 1216Å by SDO/EVE,
  the UV continua at 1600Å and 1700Å by SDO/AIA, and the white light
  continuum at 4504Å, 5550Å, and 6684Å, along with the Ca II H line
  at 3968Å using Hinode/SOT. RHESSI also observed the entire event at
  energies up to ~100keV, making it possible to determine the properties
  of the nonthermal electrons deemed to be responsible for driving the
  enhanced chromospheric emission under the assumption of thick-target
  collisions. Integrating over the duration of the impulsive phase,
  the total energy contained in the nonthermal electrons was found to be
  &gt;2×10<SUP>31</SUP> erg. By comparison, the summed energy detected by
  instruments onboard SDO and Hinode amounted to ~3×10<SUP>30</SUP> erg;
  about 15% of the total nonthermal energy. The Lyα line was found to
  dominate the measured radiative losses in contrast to the predictions
  of numerical simulations. Parameters of both the driving electron
  distribution and the resulting chromospheric response are presented
  in detail to encourage the numerical modeling of flare heating for
  this event to determine the depth of the solar atmosphere at which
  these line and continuum processes originate, and the mechanism(s)
  responsible for their generation.

---------------------------------------------------------
Title: Transit spectroscopy with James Webb Space Telescope:
    systematics, starspots and stitching
Authors: Barstow, J. K.; Aigrain, S.; Irwin, P. G. J.; Kendrew, S.;
   Fletcher, L. N.
2015MNRAS.448.2546B    Altcode: 2015arXiv150106349B
  The James Webb Space Telescope (JWST) is predicted to make great
  advances in the field of exoplanet atmospheres. Its 25 m<SUP>2</SUP>
  mirror means that it can reach unprecedented levels of precision
  in observations of transit spectra, and can thus characterize the
  atmospheres of planets orbiting stars several hundred pc away. Its
  coverage of the infrared spectral region between 0.6 and 28 μm allows
  the abundances of key molecules to be probed during the transit of a
  planet in front of the host star, and when the same planet is eclipsed
  constraints can be placed on its temperature structure. In this work,
  we explore the possibility of using low-spectral-resolution observations
  by JWST/Near-Infrared Spectrograph and JWST/Mid-Infrared Instrumen-Low
  Resolution Spectrometer together to optimize wavelength coverage
  and break degeneracies in the atmospheric retrieval problem for a
  range of exoplanets from hot Jupiters to super-Earths. This approach
  involves stitching together non-simultaneous observations in different
  wavelength regions, rendering it necessary to consider the effect of
  time-varying instrumental and astrophysical systematics. We present
  the results of a series of retrieval feasibility tests examining the
  effects of instrument systematics and starspots on the recoverability
  of the true atmospheric state, and demonstrate that correcting for
  these systematics is key for successful exoplanet science with JWST.

---------------------------------------------------------
Title: Microflares to megaflares: Solar observations and modeling
Authors: Fletcher, Lyndsay
2015HiA....16...97F    Altcode:
  The observationally determined properties of solar flares such as
  overall energy budget and distribution in space, time and energy of
  flare radiation, have improved enormously over the last cycle. This
  has enabled precision diagnostics of flare plasmas and nonthermal
  particles in large and small events, informing and driving new
  theoretical models. The theoretical challenges in understanding flare
  are considerable, involving MHD and kinetic processes operating in an
  environment far from equilibrium. New observations have also provided
  some challenges to long-standing models of flare energy release and
  transport. This talk overviewed recent observational and theoretical
  developments, and highlighted some important questions for the future

---------------------------------------------------------
Title: Stratospheric Chemistry in Saturn's Atmosphere During the
    Beacon Storm
Authors: Armstrong, E. S.; Moses, J. L.; Fletcher, L. N.; Irwin,
   P. G. J.; Hesman, B. E.; Romani, P. N.
2015LPI....46.1188A    Altcode: 2015LPICo1832.1188A
  Stratospheric chemistry is investigated to try to reconcile
  photochemical model outputs with Cassini/CIRS observations during the
  Beacon Storm (2010-12).

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Title: Optical Spectral Observations of a Flickering White-light
    Kernel in a C1 Solar Flare
Authors: Kowalski, Adam F.; Cauzzi, Gianna; Fletcher, Lyndsay
2015ApJ...798..107K    Altcode: 2014arXiv1411.0770K
  We analyze optical spectra of a two-ribbon, long-duration
  C1.1 flare that occurred on 2011 August 18 within AR 11271
  (SOL2011-08-18T15:15). The impulsive phase of the flare was observed
  with a comprehensive set of space-borne and ground-based instruments,
  which provide a range of unique diagnostics of the lower flaring
  atmosphere. Here we report the detection of enhanced continuum emission,
  observed in low-resolution spectra from 3600 Å to 4550 Å acquired
  with the Horizontal Spectrograph at the Dunn Solar Telescope. A small,
  &lt;=0.”5 (10<SUP>15</SUP> cm<SUP>2</SUP>) penumbral/umbral kernel
  brightens repeatedly in the optical continuum and chromospheric
  emission lines, similar to the temporal characteristics of the hard
  X-ray variation as detected by the Gamma-ray Burst Monitor on the Fermi
  spacecraft. Radiative-hydrodynamic flare models that employ a nonthermal
  electron beam energy flux high enough to produce the optical contrast
  in our flare spectra would predict a large Balmer jump in emission,
  indicative of hydrogen recombination radiation from the upper flare
  chromosphere. However, we find no evidence of such a Balmer jump in
  the bluemost spectral region of the continuum excess. Just redward of
  the expected Balmer jump, we find evidence of a "blue continuum bump"
  in the excess emission which may be indicative of the merging of the
  higher order Balmer lines. The large number of observational constraints
  provides a springboard for modeling the blue/optical emission for this
  particular flare with radiative-hydrodynamic codes, which are necessary
  to understand the opacity effects for the continuum and emission line
  radiation at these wavelengths.

---------------------------------------------------------
Title: A Bayesian method for detecting stellar flares
Authors: Pitkin, M.; Williams, D.; Fletcher, L.; Grant, S. D. T.
2014MNRAS.445.2268P    Altcode: 2014arXiv1406.1712P
  We present a Bayesian-odds-ratio-based algorithm for detecting stellar
  flares in light-curve data. We assume flares are described by a
  model in which there is a rapid rise with a half-Gaussian profile,
  followed by an exponential decay. Our signal model also contains a
  polynomial background model required to fit underlying light-curve
  variations in the data, which could otherwise partially mimic a
  flare. We characterize the false alarm probability and efficiency of
  this method under the assumption that any unmodelled noise in the data
  is Gaussian, and compare it with a simpler thresholding method based
  on that used in Walkowicz et al. We find our method has a significant
  increase in detection efficiency for low signal-to-noise ratio (S/N)
  flares. For a conservative false alarm probability our method can
  detect 95 per cent of flares with S/N less than 20, as compared to S/N
  of 25 for the simpler method. We also test how well the assumption of
  Gaussian noise holds by applying the method to a selection of `quiet'
  Kepler stars. As an example we have applied our method to a selection
  of stars in Kepler Quarter 1 data. The method finds 687 flaring stars
  with a total of 1873 flares after vetos have been applied. For these
  flares we have made preliminary characterizations of their durations
  and and S/N.

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Title: Neptune and Triton: Essential pieces of the Solar System puzzle
Authors: Masters, A.; Achilleos, N.; Agnor, C. B.; Campagnola, S.;
   Charnoz, S.; Christophe, B.; Coates, A. J.; Fletcher, L. N.; Jones,
   G. H.; Lamy, L.; Marzari, F.; Nettelmann, N.; Ruiz, J.; Ambrosi, R.;
   Andre, N.; Bhardwaj, A.; Fortney, J. J.; Hansen, C. J.; Helled, R.;
   Moragas-Klostermeyer, G.; Orton, G.; Ray, L.; Reynaud, S.; Sergis,
   N.; Srama, R.; Volwerk, M.
2014P&SS..104..108M    Altcode:
  The planet Neptune and its largest moon Triton hold the keys to major
  advances across multiple fields of Solar System science. The ice giant
  Neptune played a unique and important role in the process of Solar
  System formation, has the most meteorologically active atmosphere in the
  Solar System (despite its great distance from the Sun), and may be the
  best Solar System analogue of the dominant class of exoplanets detected
  to date. Neptune's moon Triton is very likely a captured Kuiper Belt
  object, holding the answers to questions about the icy dwarf planets
  that formed in the outer Solar System. Triton is geologically active,
  has a tenuous nitrogen atmosphere, and is predicted to have a subsurface
  ocean. However, our exploration of the Neptune system remains limited to
  a single spacecraft flyby, made by Voyager 2 in 1989. Here, we present
  the high-level science case for further exploration of this outermost
  planetary system, based on a white paper submitted to the European Space
  Agency (ESA) for the definition of the second and third large missions
  in the ESA Cosmic Vision Programme 2015-2025. We discuss all the major
  science themes that are relevant for further spacecraft exploration
  of the Neptune system, and identify key scientific questions in each
  area. We present an overview of the results of a European-led Neptune
  orbiter mission analysis. Such a mission has significant scope for
  international collaboration, and is essential to achieve our aim of
  understanding how the Solar System formed, and how it works today.

---------------------------------------------------------
Title: The science case for an orbital mission to Uranus: Exploring
    the origins and evolution of ice giant planets
Authors: Arridge, C. S.; Achilleos, N.; Agarwal, J.; Agnor, C. B.;
   Ambrosi, R.; André, N.; Badman, S. V.; Baines, K.; Banfield, D.;
   Barthélémy, M.; Bisi, M. M.; Blum, J.; Bocanegra-Bahamon, T.;
   Bonfond, B.; Bracken, C.; Brandt, P.; Briand, C.; Briois, C.; Brooks,
   S.; Castillo-Rogez, J.; Cavalié, T.; Christophe, B.; Coates, A. J.;
   Collinson, G.; Cooper, J. F.; Costa-Sitja, M.; Courtin, R.; Daglis,
   I. A.; de Pater, I.; Desai, M.; Dirkx, D.; Dougherty, M. K.; Ebert,
   R. W.; Filacchione, G.; Fletcher, L. N.; Fortney, J.; Gerth, I.;
   Grassi, D.; Grodent, D.; Grün, E.; Gustin, J.; Hedman, M.; Helled,
   R.; Henri, P.; Hess, S.; Hillier, J. K.; Hofstadter, M. H.; Holme,
   R.; Horanyi, M.; Hospodarsky, G.; Hsu, S.; Irwin, P.; Jackman, C. M.;
   Karatekin, O.; Kempf, S.; Khalisi, E.; Konstantinidis, K.; Krüger,
   H.; Kurth, W. S.; Labrianidis, C.; Lainey, V.; Lamy, L. L.; Laneuville,
   M.; Lucchesi, D.; Luntzer, A.; MacArthur, J.; Maier, A.; Masters, A.;
   McKenna-Lawlor, S.; Melin, H.; Milillo, A.; Moragas-Klostermeyer,
   G.; Morschhauser, A.; Moses, J. I.; Mousis, O.; Nettelmann, N.;
   Neubauer, F. M.; Nordheim, T.; Noyelles, B.; Orton, G. S.; Owens, M.;
   Peron, R.; Plainaki, C.; Postberg, F.; Rambaux, N.; Retherford, K.;
   Reynaud, S.; Roussos, E.; Russell, C. T.; Rymer, A. M.; Sallantin, R.;
   Sánchez-Lavega, A.; Santolik, O.; Saur, J.; Sayanagi, K. M.; Schenk,
   P.; Schubert, J.; Sergis, N.; Sittler, E. C.; Smith, A.; Spahn, F.;
   Srama, R.; Stallard, T.; Sterken, V.; Sternovsky, Z.; Tiscareno,
   M.; Tobie, G.; Tosi, F.; Trieloff, M.; Turrini, D.; Turtle, E. P.;
   Vinatier, S.; Wilson, R.; Zarka, P.
2014P&SS..104..122A    Altcode:
  Giant planets helped to shape the conditions we see in the Solar System
  today and they account for more than 99% of the mass of the Sun's
  planetary system. They can be subdivided into the Ice Giants (Uranus
  and Neptune) and the Gas Giants (Jupiter and Saturn), which differ
  from each other in a number of fundamental ways. Uranus, in particular
  is the most challenging to our understanding of planetary formation
  and evolution, with its large obliquity, low self-luminosity, highly
  asymmetrical internal field, and puzzling internal structure. Uranus
  also has a rich planetary system consisting of a system of inner natural
  satellites and complex ring system, five major natural icy satellites,
  a system of irregular moons with varied dynamical histories, and a
  highly asymmetrical magnetosphere. Voyager 2 is the only spacecraft to
  have explored Uranus, with a flyby in 1986, and no mission is currently
  planned to this enigmatic system. However, a mission to the uranian
  system would open a new window on the origin and evolution of the
  Solar System and would provide crucial information on a wide variety
  of physicochemical processes in our Solar System. These have clear
  implications for understanding exoplanetary systems. In this paper
  we describe the science case for an orbital mission to Uranus with
  an atmospheric entry probe to sample the composition and atmospheric
  physics in Uranus' atmosphere. The characteristics of such an orbiter
  and a strawman scientific payload are described and we discuss the
  technical challenges for such a mission. This paper is based on a white
  paper submitted to the European Space Agency's call for science themes
  for its large-class mission programme in 2013.

---------------------------------------------------------
Title: Scientific rationale for Saturn's in situ exploration
Authors: Mousis, O.; Fletcher, L. N.; Lebreton, J. -P.; Wurz, P.;
   Cavalié, T.; Coustenis, A.; Courtin, R.; Gautier, D.; Helled, R.;
   Irwin, P. G. J.; Morse, A. D.; Nettelmann, N.; Marty, B.; Rousselot,
   P.; Venot, O.; Atkinson, D. H.; Waite, J. H.; Reh, K. R.; Simon, A. A.;
   Atreya, S.; André, N.; Blanc, M.; Daglis, I. A.; Fischer, G.; Geppert,
   W. D.; Guillot, T.; Hedman, M. M.; Hueso, R.; Lellouch, E.; Lunine,
   J. I.; Murray, C. D.; O`Donoghue, J.; Rengel, M.; Sánchez-Lavega, A.;
   Schmider, F. -X.; Spiga, A.; Spilker, T.; Petit, J. -M.; Tiscareno,
   M. S.; Ali-Dib, M.; Altwegg, K.; Bolton, S. J.; Bouquet, A.; Briois,
   C.; Fouchet, T.; Guerlet, S.; Kostiuk, T.; Lebleu, D.; Moreno, R.;
   Orton, G. S.; Poncy, J.
2014P&SS..104...29M    Altcode: 2014arXiv1404.4811M
  Remote sensing observations meet some limitations when used to study
  the bulk atmospheric composition of the giant planets of our solar
  system. A remarkable example of the superiority of in situ probe
  measurements is illustrated by the exploration of Jupiter, where key
  measurements such as the determination of the noble gases' abundances
  and the precise measurement of the helium mixing ratio have only been
  made available through in situ measurements by the Galileo probe. This
  paper describes the main scientific goals to be addressed by the future
  in situ exploration of Saturn placing the Galileo probe exploration of
  Jupiter in a broader context and before the future probe exploration of
  the more remote ice giants. In situ exploration of Saturn's atmosphere
  addresses two broad themes that are discussed throughout this paper:
  first, the formation history of our solar system and second, the
  processes at play in planetary atmospheres. In this context, we detail
  the reasons why measurements of Saturn's bulk elemental and isotopic
  composition would place important constraints on the volatile reservoirs
  in the protosolar nebula. We also show that the in situ measurement of
  CO (or any other disequilibrium species that is depleted by reaction
  with water) in Saturn's upper troposphere may help constraining its
  bulk O/H ratio. We compare predictions of Jupiter and Saturn's bulk
  compositions from different formation scenarios, and highlight the key
  measurements required to distinguish competing theories to shed light
  on giant planet formation as a common process in planetary systems with
  potential applications to most extrasolar systems. In situ measurements
  of Saturn's stratospheric and tropospheric dynamics, chemistry and
  cloud-forming processes will provide access to phenomena unreachable to
  remote sensing studies. Different mission architectures are envisaged,
  which would benefit from strong international collaborations, all based
  on an entry probe that would descend through Saturn's stratosphere and
  troposphere under parachute down to a minimum of 10 bar of atmospheric
  pressure. We finally discuss the science payload required on a Saturn
  probe to match the measurement requirements.

---------------------------------------------------------
Title: Long-Term Time Variability of Temperature, Gas Abundance and
    Cloud Fields in Jupiter from Thermal Emission Observations
Authors: Orton, G. S.; Fletcher, L. N.; Yanamandra-Fisher, P. A.;
   Fisher, B.; Greathouse, T. K.; Liu, J.; Schneider, T.; Kim, S.
2014AGUFM.P23A3973O    Altcode:
  Mid-infrared raster-scans and 2D images of Jupiter's thermal emission in
  discrete filters between 4.8 and 24.5 μm have been have covered nearly
  2 Jovian years, enabling time-domain studies of its temperature field,
  minor-constituent distribution and cloud properties. The behavior of
  stratospheric (~10-mbar) and tropospheric (~100-400 mbar) temperatures
  is generally consistent with predictions of seasonal variability. These
  also appear to be long-term periodicities of tropospheric temperatures,
  with meridionally dependent amplitudes, phases and periods. Temperatures
  near and south of the equator vary least. There were no variations of
  zonal mean temperatures associated with any of the "global upheaval"
  or the corresponding "revival" events that have produced dramatic
  changes of Jupiter's visible appearance and cloud cover, although
  there are colder discrete regions associated with the updraft events
  that marked the early stages of revivals. Changes visible albedo
  are accompanied by increases in cloudiness at 700 mbar and higher
  pressures, together with the mixing ratio of NH3 gas. In contrast to
  all these changes, the meridional distribution of the 240-mbar para-H2
  fraction appears to be time-invariant. Jupiter also exhibits prominent
  temperature waves in both the upper troposphere and stratosphere that
  move slowly retrograde in System III. Unlike Saturn's slowly moving
  waves, these waves are ubiquitous at certain latitudes and at all
  longitudes therein. The time scale for coherence of these waves is
  somewhere between a few days and 4 weeks. These waves are consistent
  with convectively generated Rossby waves.

---------------------------------------------------------
Title: The Europa Imaging System (EIS): High-Resolution, 3-D Insight
    into Europa's Geology, Ice Shell, and Potential for Current Activity
Authors: Turtle, E. P.; McEwen, A. S.; Collins, G. C.; Fletcher, L. N.;
   Hansen, C. J.; Hayes, A.; Hurford, T., Jr.; Kirk, R. L.; Barr, A.;
   Nimmo, F.; Patterson, G.; Quick, L. C.; Soderblom, J. M.; Thomas, N.
2014AGUFM.P13E..03T    Altcode:
  The Europa Imaging System will transform our understanding of Europa
  through global decameter-scale coverage, three-dimensional maps,
  and unprecedented meter-scale imaging. EIS combines narrow-angle and
  wide-angle cameras (NAC and WAC) designed to address high-priority
  Europa science and reconnaissance goals. It will: (A) Characterize
  the ice shell by constraining its thickness and correlating surface
  features with subsurface structures detected by ice penetrating
  radar; (B) Constrain formation processes of surface features and
  the potential for current activity by characterizing endogenic
  structures, surface units, global cross-cutting relationships, and
  relationships to Europa's subsurface structure, and by searching
  for evidence of recent activity, including potential plumes; and (C)
  Characterize scientifically compelling landing sites and hazards by
  determining the nature of the surface at scales relevant to a potential
  lander. The NAC provides very high-resolution, stereo reconnaissance,
  generating 2-km-wide swaths at 0.5-m pixel scale from 50-km altitude,
  and uses a gimbal to enable independent targeting. NAC observations
  also include: near-global (&gt;95%) mapping of Europa at ≤50-m
  pixel scale (to date, only ~14% of Europa has been imaged at ≤500
  m/pixel, with best pixel scale 6 m); regional and high-resolution
  stereo imaging at &lt;1-m/pixel; and high-phase-angle observations
  for plume searches. The WAC is designed to acquire pushbroom stereo
  swaths along flyby ground-tracks, generating digital topographic
  models with 32-m spatial scale and 4-m vertical precision from 50-km
  altitude. These data support characterization of cross-track clutter
  for radar sounding. The WAC also performs pushbroom color imaging
  with 6 broadband filters (350-1050 nm) to map surface units and
  correlations with geologic features and topography. EIS will provide
  comprehensive data sets essential to fulfilling the goal of exploring
  Europa to investigate its habitability and perform collaborative science
  with other investigations, including cartographic and geologic maps,
  regional and high-resolution digital topography, GIS products, color
  and photometric data products, a geodetic control network tied to
  radar altimetry, and a database of plume-search observations.

---------------------------------------------------------
Title: Photochemistry in Saturn's Ring-Shadowed Atmosphere: Modeling
    of Key Molecules and Observations of Dust Content
Authors: Edgington, S. G.; Atreya, S. K.; Wilson, E. H.; West, R. A.;
   Fletcher, L. N.; Baines, K. H.; Bjoraker, G. L.; Momary, T.
2014AGUFM.P23A3975E    Altcode:
  Cassini has been orbiting Saturn for over ten years now. During this
  epoch, the ring shadow has moved from covering a large portion of the
  northern hemisphere to covering a large swath south of the equator
  and continues to move southward. At Saturn Orbit Insertion in 2004,
  the ring plane was inclined by ~24 degrees relative to the Sun-Saturn
  vector. The projection of the B-ring onto Saturn reached as far as 40N
  along the central meridian (~52N at the terminator). At its maximum
  extent, the ring shadow can reach as far as 48N/S (~58N/S at the
  terminator). The net effect is that the intensity of both ultraviolet
  and visible sunlight penetrating into any particular latitude will vary
  depending on both Saturn's axis relative to the Sun and the optical
  thickness of each ring system. In essence, the rings act like venetian
  blinds. Our previous work [1] examined the variation of the solar
  flux as a function of solar inclination, i.e. ~7.25 year season at
  Saturn. Here, we report on the impact of the oscillating ring shadow
  on the photolysis and production rates of hydrocarbons in Saturn's
  stratosphere and upper troposphere, including acetylene, ethane,
  propane, and benzene. Beginning with methane, we investigate the impact
  on production and loss rates of the long-lived photochemical products
  leading to haze formation are examined at several latitudes over a
  Saturn year. Similarly, we assess its impact on phosphine abundance,
  a disequilibrium species whose presence in the upper troposphere is
  a tracer of convective processes in the deep atmosphere. We will also
  present our ongoing analysis of Cassini's CIRS, UVIS, and VIMS datasets
  that provide an estimate of the evolving haze content of the northern
  hemisphere and we will begin to assess the implications for dynamical
  mixing. In particular, we will examine how the now famous hexagonal
  jet stream acts like a barrier to transport, isolating Saturn's north
  polar region from outside transport of photochemically-generated
  molecules and haze. [1] Edgington, S.G., et al., 2012. Photochemistry
  in Saturn's Ring Shadowed Atmosphere: Modeling, Observations, and
  Preliminary Analysis. Bull. American. Astron. Soc., 38, 499 (#11.23).

---------------------------------------------------------
Title: On the Origin of a Sunquake during the 2014 March 29 X1 Flare
Authors: Judge, Philip G.; Kleint, Lucia; Donea, Alina; Sainz Dalda,
   Alberto; Fletcher, Lyndsay
2014ApJ...796...85J    Altcode: 2014arXiv1409.6268J
  Helioseismic data from the Helioseismic Magnetic Imager instrument have
  revealed a sunquake associated with the X1 flare SOL2014-03-29T17:48
  in active region NOAA 12017. We try to discover if acoustic-like
  impulses or actions of the Lorentz force caused the sunquake. We
  analyze spectropolarimetric data obtained with the Facility Infrared
  Spectrometer (FIRS) at the Dunn Solar Telescope (DST). Fortunately,
  the FIRS slit crossed the flare kernel close to the acoustic source
  during the impulsive phase. The infrared FIRS data remain unsaturated
  throughout the flare. Stokes profiles of lines of Si I 1082.7 nm and He
  I 1083.0 nm are analyzed. At the flare footpoint, the Si I 1082.7 nm
  core intensity increases by a factor of several, and the IR continuum
  increases by 4% ± 1%. Remarkably, the Si I core resembles the classical
  Ca II K line's self-reversed profile. With nLTE radiative models of
  H, C, Si, and Fe, these properties set the penetration depth of flare
  heating to 100 ± 100 km (i.e., photospheric layers). Estimates of the
  non-magnetic energy flux are at least a factor of two less than the
  sunquake energy flux. Milne-Eddington inversions of the Si I line show
  that the local magnetic energy changes are also too small to drive the
  acoustic pulse. Our work raises several questions. Have we missed the
  signature of downward energy propagation? Is it intermittent in time
  and/or non-local? Does the 1-2 s photospheric radiative damping time
  discount compressive modes? <P />The National Center for Atmospheric
  Research is sponsored by the National Science Foundation.

---------------------------------------------------------
Title: Constraints on Jupiter's stratospheric HCl abundance and
    chlorine cycle from Herschel/HIFI
Authors: Teanby, N. A.; Showman, A. P.; Fletcher, L. N.; Irwin,
   P. G. J.
2014P&SS..103..250T    Altcode:
  Detection of HCl on Jupiter would provide insight into the chlorine
  cycle and external elemental fluxes on giant planets, yet so far
  has not been possible. Here we present the most sensitive search for
  Jupiter's stratospheric HCl to date using observations of the 625.907
  and 1876.221 GHz spectral lines with Herschel's HIFI instrument. HCl
  was not detected, but we determined the most stringent upper limits so
  far, improving on previous studies by two orders of magnitude. If HCl is
  assumed to be uniformly mixed, with a constant volume mixing ratio above
  the 1 mbar pressure level and has zero abundance below, we obtain a
  3-σ upper limit of 0.061 ppb; in contrast, if we assume uniform mixing
  above the 1 mbar level and allow a non-zero but downward-decreasing
  abundance from 1 mbar to the troposphere based on eddy diffusion, we
  obtain a 3-σ upper limit of 0.027 ppb. This is below the abundance
  expected for a solar composition cometary source and implies that
  upper stratospheric HCl loss processes are required for consistency
  with observations of the external oxygen flux. We investigated loss
  via aerosol scavenging using a simple diffusion model and conclude
  that it could be a very effective mechanism for HCl removal. Transient
  scavenging by stratospheric NH<SUB>3</SUB> from impacts is another
  potentially important loss mechanism. This suggests that it is
  extremely unlikely that HCl is present in sufficient quantities to
  be detectable in the near future. An alternative explanation for our
  very low upper limits could be that HCl is sub-solar in comets or that
  cometary chlorine exists in inactive reservoirs that are not readily
  converted to HCl during the impact process.

---------------------------------------------------------
Title: The transit spectra of Earth and Jupiter
Authors: Irwin, P. G. J.; Barstow, J. K.; Bowles, N. E.; Fletcher,
   L. N.; Aigrain, S.; Lee, J. -M.
2014Icar..242..172I    Altcode: 2014arXiv1408.3914I
  In recent years, an increasing number of observations have been made
  of the transits of 'Hot Jupiters', such as HD 189733b, about their
  parent stars from the visible through to mid-infrared wavelengths,
  which have been modelled to derive the likely atmospheric structure
  and composition of these planets. As measurement techniques improve,
  the measured transit spectra of 'Super-Earths' such as GJ 1214b are
  becoming better constrained, allowing model atmospheric states to be
  fitted for this class of planet also. While it is not yet possible to
  constrain the atmospheric states of small planets such as the Earth or
  cold planets like Jupiter, it is hoped that this might become practical
  in the coming decades and if so, it is of interest to determine what we
  might infer from such measurements. In this work we have constructed
  atmospheric models of the Solar System planets from 0.4 to 15.5 μm
  that are consistent with ground-based and satellite observations and
  from these calculate the primary transit and secondary eclipse spectra
  (with respect to the Sun and typical M-dwarfs) that would be observed
  by a 'remote observer', many light years away. From these spectra we
  test what current retrieval models might infer about their atmospheric
  states and compare these with the 'ground truths' in order to assess:
  (a) the inherent uncertainties in transit spectra observations; (b)
  the relative merits of primary transit and secondary eclipse spectra;
  and (c) the advantages of acquiring directly imaged spectra of these
  planets. We find that observing secondary eclipses of the Solar System
  would not give sufficient information for determining atmospheric
  properties with 10 m-diameter telescopes from a distance of 10 light
  years, but that primary transits give much better information. We find
  that a single transit of Jupiter in front of the Sun could potentially
  be used to determine temperature and stratospheric composition, but
  for the Earth the mean atmospheric composition could only be determined
  if it were orbiting a much smaller M-dwarf. For both Jupiter and Earth
  we note that direct imaging with sufficient nulling of the light from
  the parent star theoretically provides the best method of determining
  the atmospheric properties of such planets.

---------------------------------------------------------
Title: Instrumental methods for professional and amateur
    collaborations in planetary astronomy
Authors: Mousis, O.; Hueso, R.; Beaulieu, J. -P.; Bouley, S.; Carry,
   B.; Colas, F.; Klotz, A.; Pellier, C.; Petit, J. -M.; Rousselot,
   P.; Ali-Dib, M.; Beisker, W.; Birlan, M.; Buil, C.; Delsanti, A.;
   Frappa, E.; Hammel, H. B.; Levasseur-Regourd, A. C.; Orton, G. S.;
   Sánchez-Lavega, A.; Santerne, A.; Tanga, P.; Vaubaillon, J.; Zanda,
   B.; Baratoux, D.; Böhm, T.; Boudon, V.; Bouquet, A.; Buzzi, L.;
   Dauvergne, J. -L.; Decock, A.; Delcroix, M.; Drossart, P.; Esseiva,
   N.; Fischer, G.; Fletcher, L. N.; Foglia, S.; Gómez-Forrellad, J. M.;
   Guarro-Fló, J.; Herald, D.; Jehin, E.; Kugel, F.; Lebreton, J. -P.;
   Lecacheux, J.; Leroy, A.; Maquet, L.; Masi, G.; Maury, A.; Meyer,
   F.; Pérez-Hoyos, S.; Rajpurohit, A. S.; Rinner, C.; Rogers, J. H.;
   Roques, F.; Schmude, R. W.; Sicardy, B.; Tregon, B.; Vanhuysse, M.;
   Wesley, A.; Widemann, T.
2014ExA....38...91M    Altcode: 2013arXiv1305.3647M; 2014ExA...tmp...35M
  Amateur contributions to professional publications have increased
  exponentially over the last decades in the field of planetary
  astronomy. Here we review the different domains of the field in
  which collaborations between professional and amateur astronomers are
  effective and regularly lead to scientific publications.We discuss
  the instruments, detectors, software and methodologies typically used
  by amateur astronomers to collect the scientific data in the different
  domains of interest. Amateur contributions to the monitoring of planets
  and interplanetary matter, characterization of asteroids and comets,
  as well as the determination of the physical properties of Kuiper Belt
  Objects and exoplanets are discussed.

---------------------------------------------------------
Title: The Radiated Energy Budget of Chromospheric Plasma in a Major
    Solar Flare Deduced from Multi-wavelength Observations
Authors: Milligan, Ryan O.; Kerr, Graham S.; Dennis, Brian R.; Hudson,
   Hugh S.; Fletcher, Lyndsay; Allred, Joel C.; Chamberlin, Phillip C.;
   Ireland, Jack; Mathioudakis, Mihalis; Keenan, Francis P.
2014ApJ...793...70M    Altcode: 2014arXiv1406.7657M
  This paper presents measurements of the energy radiated by the lower
  solar atmosphere, at optical, UV, and EUV wavelengths, during an
  X-class solar flare (SOL2011-02-15T01:56) in response to an injection
  of energy assumed to be in the form of nonthermal electrons. Hard
  X-ray observations from RHESSI were used to track the evolution of
  the parameters of the nonthermal electron distribution to reveal the
  total power contained in flare accelerated electrons. By integrating
  over the duration of the impulsive phase, the total energy contained
  in the nonthermal electrons was found to be &gt;2 × 10<SUP>31</SUP>
  erg. The response of the lower solar atmosphere was measured in
  the free-bound EUV continua of H I (Lyman), He I, and He II, plus
  the emission lines of He II at 304 Å and H I (Lyα) at 1216 Å by
  SDO/EVE, the UV continua at 1600 Å and 1700 Å by SDO/AIA, and the
  white light continuum at 4504 Å, 5550 Å, and 6684 Å, along with the
  Ca II H line at 3968 Å using Hinode/SOT. The summed energy detected
  by these instruments amounted to ~3 × 10<SUP>30</SUP> erg about 15%
  of the total nonthermal energy. The Lyα line was found to dominate
  the measured radiative losses. Parameters of both the driving electron
  distribution and the resulting chromospheric response are presented
  in detail to encourage the numerical modeling of flare heating for
  this event, to determine the depth of the solar atmosphere at which
  these line and continuum processes originate, and the mechanism(s)
  responsible for their generation.

---------------------------------------------------------
Title: Onset of Electron Acceleration in a Flare Loop
Authors: Sharykin, Ivan; Liu, Siming; Fletcher, Lyndsay
2014ApJ...793...25S    Altcode: 2014arXiv1408.1413S
  We carried out a detailed analysis of X-ray and radio observations of a
  simple flare loop that occurred on 2002 August 12, with the impulsive
  hard X-ray (HXR) light curves dominated by a single pulse. The
  emission spectra of the early impulsive phase are consistent with
  an isothermal model in the coronal loop with a temperature reaching
  several keV. A power-law high-energy spectral tail is evident near the
  HXR peak time, in accordance with the appearance of footpoints at high
  energies, and is well correlated with the radio emission. The energy
  content of the thermal component keeps increasing gradually after
  the disappearance of this nonthermal component. These results suggest
  that electron acceleration only covers the central period of a longer
  and more gradual energy dissipation process and that the electron
  transport within the loop plays a crucial role in the formation of
  the inferred power-law electron distribution. The spectral index of
  power-law photons shows a very gradual evolution, indicating that the
  electron accelerator is in a quasi-steady state, which is confirmed by
  radio observations. These results are consistent with the theory of
  stochastic electron acceleration from a thermal background. Advanced
  modeling with coupled electron acceleration and spatial transport
  processes is needed to explain these observations more quantitatively,
  which may reveal the dependence of the electron acceleration on the
  spatial structure of the acceleration region.

---------------------------------------------------------
Title: BayesFlare: Bayesian method for detecting stellar flares
Authors: Pitkin, M.; Williams, D.; Fletcher, L.; Grant, S. D. T.
2014ascl.soft07015P    Altcode:
  BayesFlare identifies flaring events in light curves released by
  the Kepler mission; it identifies even weak events by making use of
  the flare signal shape. The package contains functions to perform
  Bayesian hypothesis testing comparing the probability of light curves
  containing flares to that of them containing noise (or non-flare-like)
  artifacts. BayesFlare includes functions in its amplitude-marginalizer
  suite to account for underlying sinusoidal variations in light curve
  data; it includes such variations in the signal model, and then
  analytically marginalizes over them.

---------------------------------------------------------
Title: Thermal Emission Constraints on the Atmospheres of Uranus
    and Neptune
Authors: Orton, G. S.; Fletcher, L. N.; Moses, J. I.; Lellouch, E.;
   Moreno, R.; Swinyard, B. M.; Hofstadter, M. D.; Greathouse, T. K.
2014LPICo1798.2002O    Altcode:
  Photometric and spectroscopic observations of Uranus and Neptune have
  been analyzed from both spacecraft and Earth-based platforms, in order
  to create self-consistent models of their temperature fields and the
  distribution of trace gases.

---------------------------------------------------------
Title: Where is the Chromospheric Response to Conductive Energy
    Input from a Hot Pre-flare Coronal Loop?
Authors: Battaglia, Marina; Fletcher, Lyndsay; Simões, Paulo J. A.
2014ApJ...789...47B    Altcode: 2014arXiv1405.4621B
  Before the onset of a flare is observed in hard X-rays, there is often
  a prolonged pre-flare or pre-heating phase with no detectable hard X-ray
  emission but pronounced soft X-ray emission, which suggests that energy
  is already being released and deposited into the corona and chromosphere
  at this stage. This work analyzes the temporal evolution of coronal
  source heating and the chromospheric response during this pre-heating
  phase to investigate the origin and nature of early energy release and
  transport during a solar flare. Simultaneous X-ray, EUV, and microwave
  observations of a well-observed flare with a prolonged pre-heating phase
  are analyzed to study the time evolution of the thermal emission and
  to determine the onset of particle acceleration. During the 20 minute
  duration of the pre-heating phase we find no hint of accelerated
  electrons in either hard X-rays or microwave emission. However,
  the total energy budget during the pre-heating phase suggests that
  energy must be supplied to the flaring loop to sustain the observed
  temperature and emission measure. Under the assumption of this energy
  being transported toward the chromosphere via thermal conduction,
  significant energy deposition at the chromosphere is expected. However,
  no detectable increase of the emission in the AIA wavelength channels
  sensitive to chromospheric temperatures is observed. The observations
  suggest energy release and deposition in the flaring loop before the
  onset of particle acceleration, yet a model in which energy is conducted
  to the chromosphere and subsequent heating of the chromosphere is not
  supported by the observations.

---------------------------------------------------------
Title: Scientific Rationale and Concepts for an In Situ Saturn Probe
Authors: Mousis, O.; Coustenis, A.; Lebreton, J. -P.; Atkinson,
   D. H.; Lunine, J. I.; Rey, K.; Fletcher, L. N.; Simon-Miller, A.;
   Atreya, S.; Brinckerhoff, W.; Cavalié, T.; Colaprete, A.; Gautier,
   D.; Guillot, T.; Hueso, R.; Mahaffy, P.; Marty, B.; Morse, A. D.;
   Sims, J.; Spilker, T.; Spilker, L.; Webster, C.; Waite, J. H.; Wurz, P.
2014LPICo1795.8094M    Altcode:
  We summarize the science case for in situ measurements at Saturn and
  discuss the possible mission concepts that would be consistent with
  the constraints of ESA M-class missions.

---------------------------------------------------------
Title: F-CHROMA.Flare Chromospheres: Observations, Models and Archives
Authors: Cauzzi, Gianna; Fletcher, Lyndsay; Mathioudakis, Mihalis;
   Carlsson, Mats; Heinzel, Petr; Berlicki, Arek; Zuccarello, Francesca
2014AAS...22412339C    Altcode:
  F-CHROMA is a collaborative project newly funded under the EU-Framework
  Programme 7 "FP7-SPACE-2013-1", involving seven different European
  research Institutes and Universities. The goal of F-CHROMA is to
  substantially advance our understanding of the physics of energy
  dissipation and radiation in the flaring solar atmosphere, with a
  particular focus on the flares' chromosphere. A major outcome of the
  F-CHROMA project will be the creation of an archive of chromospheric
  flare observations and models to be made available to the community
  for further research.In this poster we describe the structure and
  milestones of the project, the different activities planned, as well
  as early results. Emphasis will be given to the dissemination efforts
  of the project to make results of these activities available to and
  usable by the community.

---------------------------------------------------------
Title: In Situ Probe Science at Saturn
Authors: Atkinson, D. H.; Lunine, J. I.; Simon-Miller, A. A.; Atreya,
   S. K.; Brinckerhoff, W.; Colaprete, A.; Coustenis, A.; Fletcher, L. N.;
   Guillot, T.; Lebreton, J. -P.; Mahaffy, P.; Mousis, O.; Orton, G. S.;
   Reh, K.; Spilker, L. J.; Spilker, T. R.; Webster, C.
2014LPICo1795.8005A    Altcode:
  Key to understanding solar system formation and evolution is the origin
  and evolution of the giant planets. A small shallow Saturn probe can
  serve to test competing theories of solar system and giant planet
  origin, chemical, and dynamical evolution.

---------------------------------------------------------
Title: From Voyager-IRIS to Cassini-CIRS: Interannual variability
    in Saturn’s stratosphere?
Authors: Sinclair, J. A.; Irwin, P. G. J.; Fletcher, L. N.; Greathouse,
   T.; Guerlet, S.; Hurley, J.; Merlet, C.
2014Icar..233..281S    Altcode:
  We present an intercomparison of Saturn’s stratosphere between
  Voyager 1-IRIS observations in 1980 and Cassini-CIRS observations in
  2009 and 2010. Over a saturnian year (∼29.5 years) has now passed
  since the Voyager flybys of Saturn in 1980/1981. Cassini observations
  in 2009/2010 capture Saturn in the same season as Voyager observations
  (just after the vernal equinox) but one year later. Any differences
  in Saturn’s atmospheric properties implied by a comparison of
  these two datasets could therefore reveal the extent of interannual
  variability. We retrieve temperature and stratospheric acetylene and
  ethane concentrations from Voyager 1-IRIS (Δν∼=4.3 cm<SUP>-1</SUP>)
  observations in 1980 and Cassini-CIRS (Δν∼=15.5 cm<SUP>-1</SUP>)
  ‘FIRMAP’ observations in 2009 and 2010. We observe a difference
  in temperature at the equator of 7.1 ± 1.2 K at the 2.1-mbar level
  that implies that the two datasets have captured Saturn’s semiannual
  oscillation (SSAO) in a slightly different phase suggesting that its
  period is more quasi-semiannual. Elevated concentrations of acetylene
  at 25°S in 1980 with respect to 2010 imply stronger downwelling
  at the former date which may also be explained by a difference in
  the phase of the SSAO and its dynamical forcing at low latitudes. At
  high-southern and high-northern latitudes, stratospheric temperatures
  and hydrocarbon concentrations appear elevated in 1980 with respect
  to 2009/2010. This could be an artefact of the low signal-to-noise
  ratio of the corresponding observations but might also be explained
  by increased auroral activity during solar maximum in 1980.

---------------------------------------------------------
Title: Changes to Saturn's Zonal-mean Tropospheric Thermal Structure
    after the 2010-2011 Northern Hemisphere Storm
Authors: Achterberg, R. K.; Gierasch, P. J.; Conrath, B. J.; Fletcher,
   L. N.; Hesman, B. E.; Bjoraker, G. L.; Flasar, F. M.
2014ApJ...786...92A    Altcode:
  We use far-infrared (20-200 μm) data from the Composite Infrared
  Spectrometer on the Cassini spacecraft to determine the zonal-mean
  temperature and hydrogen para-fraction in Saturn's upper troposphere
  from observations taken before and after the large northern hemisphere
  storm in 2010-2011. During the storm, zonal mean temperatures in the
  latitude band between approximately 25°N and 45°N (planetographic
  latitude) increased by about 3 K, while the zonal mean hydrogen
  para-fraction decreased by about 0.04 over the same latitudes, at
  pressures greater than about 300 mbar. These changes occurred over
  the same latitude range as the disturbed cloud band seen in visible
  images. The observations are consistent with low para-fraction gas being
  brought up from the level of the water cloud by the strong convective
  plume associated with the storm, while being heated by condensation
  of water vapor, and then advected zonally by the winds near the plume
  tops in the upper troposphere.

---------------------------------------------------------
Title: Clouds on the Hot Jupiter HD189733b: Constraints from the
    Reflection Spectrum
Authors: Barstow, J. K.; Aigrain, S.; Irwin, P. G. J.; Hackler, T.;
   Fletcher, L. N.; Lee, J. M.; Gibson, N. P.
2014ApJ...786..154B    Altcode: 2014arXiv1403.6664B
  The hot Jupiter HD 189733b is probably the best studied of the known
  extrasolar planets, with published transit and eclipse spectra covering
  the near UV to mid-IR range. Recent work on the transmission spectrum
  has shown clear evidence for the presence of clouds in its atmosphere,
  which significantly increases the model atmosphere parameter space
  that must be explored in order to fully characterize this planet. In
  this work, we apply the NEMESIS atmospheric retrieval code to the
  recently published HST/STIS reflection spectrum, and also to the dayside
  thermal emission spectrum in light of new Spitzer/IRAC measurements,
  as well as our own re-analysis of the HST/NICMOS data. We first use
  the STIS data to place some constraints on the nature of clouds on
  HD 189733b and explore solution degeneracy between different cloud
  properties and the abundance of Na in the atmosphere; as already
  noted in previous work, absorption due to Na plays a significant
  role in determining the shape of the reflection spectrum. We then
  perform a new retrieval of the temperature profile and abundances
  of H<SUB>2</SUB>O, CO<SUB>2</SUB>, CO, and CH<SUB>4</SUB> from the
  dayside thermal emission spectrum. Finally, we investigate the effect
  of including cloud in the model on this retrieval process. We find
  that the current quality of data does not warrant the extra complexity
  introduced by including cloud in the model; however, future data are
  likely to be of sufficient resolution and signal-to-noise that a more
  complete model, including scattering particles, will be required.

---------------------------------------------------------
Title: In situ Probe Science at Saturn
Authors: Atkinson, D. H.; Mousis, O.; Lunine, J. I.; Simon-Miller,
   A. A.; Atreya, S. K.; Brinckerhoff, W.; Colaprete, A.; Coustenis, A.;
   Fletcher, L. N.; Guillot, T.; Lebreton, J. -P.; Mahaffy, P.; Orton,
   G. S.; Reh, K.; Spilker, L. J.; Spilker, T. R.; Webster, C.
2014EPSC....9...12A    Altcode:
  A fundamental goal of solar system exploration is to understand
  the origin of the solar system, the initial stages, conditions, and
  processes by which the solar system formed, how the formation process
  was initiated, and the nature of the interstellar seed material from
  which the solar system was born. Key to understanding solar system
  formation and subsequent dynamical and chemical evolution is the origin
  and evolution of the giant planets and their atmospheres. Several
  theories have been put forward to explain the process of solar system
  formation, and the origin and evolution of the giant planets and
  their atmospheres. Each theory offers quantifiable predictions of the
  abundances of noble gases He, Ne, Ar, Kr, and Xe, and abundances of key
  isotopic ratios 4He/3He, D/H, 15N/14N, 18O/16O, and 13C/12C. Detection
  of certain disequilibrium species, diagnostic of deeper internal
  processes and dynamics of the atmosphere, would also help discriminate
  between competing theories. Measurements of the critical abundance
  profiles of these key constituents into the deeper well-mixed atmosphere
  must be complemented by measurements of the profiles of atmospheric
  structure and dynamics at high vertical resolution and also require in
  situ exploration. The atmospheres of the giant planets can also serve
  as laboratories to better understand the atmospheric chemistries,
  dynamics, processes, and climates on all planets including Earth,
  and offer a context and provide a ground truth for exoplanets and
  exoplanetary systems. Additionally, Giant planets have long been
  thought to play a critical role in the development of potentially
  habitable planetary systems. In the context of giant planet science
  provided by the Galileo, Juno, and Cassini missions to Jupiter and
  Saturn, a small, relatively shallow Saturn probe capable of measuring
  abundances and isotopic ratios of key atmospheric constituents, and
  atmospheric structure including pressures, temperatures, dynamics,
  and cloud locations and properties not accessible by remote sensing
  can serve to test competing theories of solar system and giant planet
  origin, chemical, and dynamical evolution.

---------------------------------------------------------
Title: Cycle 23 Variation in Solar Flare Productivity
Authors: Hudson, Hugh; Fletcher, Lyndsay; McTiernan, Jim
2014SoPh..289.1341H    Altcode: 2014arXiv1401.6474H
  The NOAA listings of solar flares in cycles 21 - 24, including the GOES
  soft X-ray magnitudes, enable a simple determination of the number of
  flares each flaring active region produces over its lifetime. We have
  studied this measure of flare productivity over the interval 1975 -
  2012. The annual averages of flare productivity remained approximately
  constant during cycles 21 and 22, at about two reported M- or X-flares
  per region, but then increased significantly in the declining phase
  of cycle 23 (the years 2004 - 2005). We have confirmed this by using
  the independent RHESSI flare catalog to check the NOAA events listings
  where possible. We note that this measure of solar activity does not
  correlate with the solar cycle. The anomalous peak in flare productivity
  immediately preceded the long solar minimum between cycles 23 and 24.

---------------------------------------------------------
Title: Monitoring Jovian Dynamics Using Maps of NH3 and PH3
Authors: Encrenaz, T.; Greathouse, T.; Drossart, P.; Fouchet, T.;
   Janssen, M.; Gulkis, S.; Orton, G.; Fletcher, L.; Giles, R.
2014EPSC....9..240E    Altcode:
  Phosphine and ammonia are important tracers of Jovian tropospheric
  dynamics, but their vertical distributions are still poorly known. This
  information will be needed for the analysis of the radio and infrared
  data of the JUNO mission in 2016. We have started an observing campaign
  to obtain 3D maps of NH3 and PH3 in the 0.1-5 bar pressure range,
  by using TEXES/IRTF and selecting 3 spectral ranges (at 4.65, 8.9 and
  10.5 microns) that probe 3 different pressure levels. The first data
  (Feb. 2014) allow us to map NH3 and PH3 at low latitudes. We plan to
  continue this campaign to obtain a full latitude and longitude coverage
  and to improve the sensitivity.

---------------------------------------------------------
Title: Seasonal Evolution of Saturn's Polar Atmosphere from a Decade
    of Cassini/CIRS Observations
Authors: Fletcher, L. N.; Sinclair, J. A.; Irwin, P. G. J.; Giles,
   R. S.; Orton, G. S.; Hesman, B. E.; Hurley, J.; Bjoraker, G. L.;
   Simon, A. A.
2014EPSC....9...62F    Altcode:
  Saturn's polar regions are subjected to extreme insolation variations
  over its 29.5 year orbit due to the gas giant's 26-degree axial
  tilt, causing seasonal changes to the thermal structure, chemistry,
  dynamics and cloud properties of the polar environments. Cassini's
  high inclination orbits permit detailed scrutiny of Saturn's high
  latitudes in a dataset that now spans a decade (a third of a Saturn
  year, 2004-2014), five years either side of the northern spring
  equinox in 2009. Thermal infrared Cassini/CIRS spectra (7-16 μm)
  from all mission phases are inverted to determine the rate of change
  of polar temperatures, wind shears, tropospheric phosphine (as a
  tracer of vertical mixing) and stratospheric hydrocarbons (tracers of
  middle atmospheric circulation and chemistry). Cassini's unique vantage
  point allows us to track these parameters as the summer southern pole
  receded into autumn and the winter northern pole emerged into spring
  sunlight. Results show the most rapid changes to temperature and
  composition occurring poleward of 70o in each hemisphere, in excess
  of expectations from simple radiative climate models. Small cyclonic
  vortices persist at both poles throughout theCassini mission, while the
  broad stratospheric vortices are seasonally variable. The signature
  of the northern hexagon is still present in the tropospheric thermal
  structure. At the time of writing, an infraredbright polar vortex is
  beginning to emerge at the northern spring pole, consistent with the
  historical record of Saturn observations from the 1980s (previous
  northern spring, [4]).

---------------------------------------------------------
Title: Long-term variability of temperatures and clouds in Saturn
    from ground-based observations of thermal emission
Authors: Orton, G.; Fletcher, L.; Sinclair, J.; Yanamandra-Fisher,
   P.; Greathouse, T.; Momary, T.; Fujiyoshi, T.; Aguilar, I.
2014EPSC....9..681O    Altcode:
  We report the results of long-term studies of thermal emission from
  the atmosphere of Saturn using ground-based imaging covering 1990 to
  the present. Both seasonal and non-seasonal effects have been detected
  in its atmosphere. Seasonal effects are most pronounced and indicate
  a variance from radiative climate model results that is consistent
  with an additional source of stratospheric heating other than gaseous
  absorption of sunlight. Associated with the seasonal variations is
  the establishment of warm polar vortices in the stratosphere toward
  late spring and early summer, with the anticipation of such a vortex
  appearing imminently in Saturn's north polar region. Non-seasonal
  effects include a variation of low-latitude thermal waves, initially
  identified as consistent with a semi-annual oscillation, although
  recent observations indicate a variation from that behavior. Slowly
  moving zonal thermal waves have been detected irregularly; they have
  been most prominent in Saturn's southern mid-latitudes. Deep atmospheric
  cloud structure has shown consistent zonal-mean structure from 1995 to
  the present; however it has been marked by substantial discrete opaque
  ("cold") features. The great springtime storm of 2010-2011 produced
  substantial perturbations of both atmospheric temperatures and deep
  cloud structure.

---------------------------------------------------------
Title: Interpretation of the 14N/15N ratio measured in Saturn's
    ammonia
Authors: Mousis, O.; Lunine, J. I.; Fletcher, L. N.; Mandt, K. E.;
   Gautier, D.; Atreya, S.
2014EPSC....9..425M    Altcode:
  The recent derivation of a 1-sigma lower limit for the 14N/15N ratio in
  Saturn's ammonia, which is found to be ~500 [1], prompts us to revise
  models of Saturn's formation using as constraints the abundances of
  heavy elements inferred in its atmosphere. This lower limit is found
  consistent with the 14N/15N ratio (~435) measured by the Galileo probe
  at Jupiter and implies that the two giant planets were essentially
  formed from the same nitrogen reservoir in the nebula, which is N2
  [1]. However, in contrast with Jupiter whose C and N enrichments are
  uniform, carbon is more than twice enriched in Saturn's atmosphere
  compared to nitrogen. This non-uniform enrichment at Saturn, considered
  with the recent derivation of a lower limit for the 14N/15N ratio,
  challenges the formation models elaborated so far. Here we propose an
  alternative formation scenario that may explain all these properties
  together

---------------------------------------------------------
Title: Scientific Rationale and Concepts for an In Situ Saturn Probe
Authors: Mousis, O.; Atkinson, D.; Atreya, S.; Coustenis, A.; Fletcher,
   L. N.; Gautier, D.; Guillot, T.; Hueso, R.; Lebreton, J. -P.; Lunine,
   J. I.; Marty, B.; Reh, K.; Venkatapathy, E.; Waite, J. H.; Wurz, P.
2014EPSC....9..437M    Altcode:
  We summarize the science case for in situ measurements at Saturn and
  discuss the possible mission concepts that would be consistent with
  the constraints of ESA M-class missions.

---------------------------------------------------------
Title: Possible Concepts for an In Situ Saturn Probe Mission
Authors: Coustenis, A.; Lebreton, J. -P.; Mousis, O.; Atkinson, D. H.;
   Lunine, J. I.; Reh, K.; Fletcher, L.; Simon-Miller, A.; Atreya, S. K.;
   Brinckerhoff, W.; Cavalié, T.; Colaprete, A.; Gautier, D.; Guillot,
   T.; Mahaffy, P.; Marty, B.; Morse, A. D.; Sims, J.; Spilker, T.;
   Spilker, L.; Webster, C.; Waite, J. H.; Wurz, P.
2014LPI....45.1244C    Altcode:
  We present Saturn entry probe concepts for in situ exploration
  informing us on the formation history of our solar system and the
  planet's atmosphere processes.

---------------------------------------------------------
Title: Europa's Water Vapor Plumes: Discovery with HST and Plans
    for JUICE-UVS Observations
Authors: Retherford, K. D.; Roth, L.; Saur, J.; Gladstone, G. R.;
   Nimmo, F.; McGrath, M. A.; Feldman, P. D.; Strobel, D. F.; Greathouse,
   T. K.; Davis, M. W.; Steffl, A. J.; Spencer, J. R.; Bagenal, F.;
   Fletcher, L.; Juice-UVS Team
2014LPI....45.1639R    Altcode:
  Discovery of water vapor plumes on Europa obtained with HST, and
  updated plans for JUICE Ultraviolet Spectrograph (UVS) observations.

---------------------------------------------------------
Title: Physical Properties of White-light Sources in the 2011 February
    15 Solar Flare
Authors: Kerr, G. S.; Fletcher, L.
2014ApJ...783...98K    Altcode: 2014arXiv1401.4877K
  White-light flares (WLFs) are observational rarities, making them
  understudied events. However, optical emission is a significant
  contribution to flare energy budgets and the emission mechanisms
  responsible could have important implications for flare models. Using
  Hinode SOT optical continuum data taken in broadband red, green,
  and blue filters, we investigate WL emission from the X2.2 flare
  SOL2011-02-15T01:56:00. We develop a technique to robustly identify
  enhanced flare pixels and, using a knowledge of the RGB filter
  transmissions, determined the source color temperature and effective
  temperature. We investigated two idealized models of WL emission—an
  optically thick photospheric source, and an optically thin chromospheric
  slab. Under the optically thick assumption, the color temperature and
  effective temperature of flare sources in sunspot umbra and penumbra
  were determined as a function of time and position. Values in the range
  of 5000-6000 K were found, corresponding to a blackbody temperature
  increase of a few hundred kelvin. The power emitted in the optical
  was estimated at ~10<SUP>26</SUP> erg s<SUP>-1</SUP>. In some of the
  WL sources the color and blackbody temperatures are the same within
  uncertainties, consistent with a blackbody emitter. In other regions
  this is not the case, suggesting that some other continuum emission
  process is contributing. An optically thin slab model producing hydrogen
  recombination radiation is also discussed as a potential source of
  WL emission; it requires temperatures in the range 5500-25,000 K,
  and total energies of ~10<SUP>27</SUP> erg s<SUP>-1</SUP>.

---------------------------------------------------------
Title: Exploring the diversity of Jupiter-class planets
Authors: Fletcher, L. N.; Irwin, P. G. J.; Barstow, J. K.; de Kok,
   R. J.; Lee, J. -M.; Aigrain, S.
2014RSPTA.37230064F    Altcode:
  No abstract at ADS

---------------------------------------------------------
Title: Scientific Rationale of a Saturn Probe Mission
Authors: Mousis, O.; Fletcher, L. N.; Lebreton, J. -P.; Wurz, P.;
   Cavalié, T.; Coustenis, A.; Atkinson, D. H.; Atreya, S.; Gautier,
   D.; Guillot, T.; Lunine, J. I.; Marty, B.; Morse, A. D.; Rey, K. R.;
   Simon-Miller, A.; Spilker, T.; Waite, J. H.
2014LPI....45.1261M    Altcode:
  We describe the main scientific goals to be addressed by future in
  situ exploration of Saturn.

---------------------------------------------------------
Title: Jupiter Icy Moons Explorer (JUICE): Science Objectives,
    Mission and Instruments
Authors: Plaut, J. J.; Barabash, S.; Bruzzone, L.; Dougherty, M.; Erd,
   C.; Fletcher, L.; Gladstone, R.; Grasset, O.; Gurvits, L.; Hartogh,
   P.; Hussmann, H.; Iess, L.; Jaumann, R.; Langevin, Y.; Palumbo, P.;
   Piccioni, G.; Titov, D.; Wahlund, J. -E.
2014LPI....45.2717P    Altcode:
  The JUpiter ICy Moons Explorer (JUICE) is an ESA mission that will
  fly by and observe the icy moons Europa, Ganymede, and Callisto,
  and finally orbit Ganymede.

---------------------------------------------------------
Title: In Situ Probe Science at Saturn
Authors: Atkinson, D. H.; Lunine, J. I.; Simon-Miller, A. A.; Atreya,
   S. K.; Brinckerhoff, W.; Colaprete, A.; Coustenis, A.; Fletcher, L. N.;
   Guillot, T.; Lebreton, J. -P.; Mahaffy, P.; Mousis, O.; Orton, G. S.;
   Reh, K.; Spilker, L. J.; Spilker, T. R.; Webster, C.
2014LPI....45.1377A    Altcode:
  A shallow Saturn probe measuring key atmospheric abundances and isotope
  ratios can test competing theories of solar system and giant planet
  formation.

---------------------------------------------------------
Title: Europa's Water Vapor Plumes: The Potential for Discovery with
    JUICE-UVS Observations
Authors: Retherford, K. D.; Roth, L.; Saur, J.; Gladstone, G. R.;
   Nimmo, F.; McGrath, M. A.; Feldman, P. D.; Strobel, D. F.; Steffl,
   A. J.; Greathouse, T. K.; Spencer, J. R.; Bagenal, F.; Fletcher, L. N.
2014LPICo1774.4033R    Altcode:
  Far-UV auroral imaging and stellar occultation techniques are able
  to identify whether water vapor plumes exist on Europa. Detailed
  observation plans for the JUICE Ultraviolet Spectrograph (UVS) are
  reported along with recent HST auroral imaging.

---------------------------------------------------------
Title: The first submillimeter observation of CO in the stratosphere
    of Uranus
Authors: Cavalié, T.; Moreno, R.; Lellouch, E.; Hartogh, P.; Venot,
   O.; Orton, G. S.; Jarchow, C.; Encrenaz, T.; Selsis, F.; Hersant,
   F.; Fletcher, L. N.
2014A&A...562A..33C    Altcode: 2013arXiv1311.2458C
  Context. Carbon monoxide (CO) has been detected in all giant planets and
  its origin is both internal and external in Jupiter and Neptune. Despite
  its first detection in Uranus a decade ago, the magnitude of its
  internal and external sources remains unconstrained. <BR /> Aims: We
  targeted CO lines in Uranus in the submillimeter range to constrain its
  origin. <BR /> Methods: We recorded the disk-averaged spectrum of Uranus
  with very high spectral resolution at the frequencies of CO rotational
  lines in the submillimeter range in 2011-2012. We used empirical and
  diffusion models of the atmosphere of Uranus to constrain the origin of
  CO. We also used a thermochemical model of its troposphere to derive an
  upper limit on the oxygen-to-hydrogen (O/H) ratio in the deep atmosphere
  of Uranus. <BR /> Results: We have detected the CO(8-7) rotational line
  for the first time with Herschel-HIFI. Both empirical and diffusion
  models results show that CO has an external origin. An empirical profile
  in which CO is constant above the 100 mbar level with a mole fraction
  of 7.1-9.0 × 10<SUP>-9</SUP>, depending on the adopted stratospheric
  thermal structure, reproduces the data. Sporadic and steady source
  models cannot be differentiated with our data. Taking the internal
  source model upper limit of a mole fraction of 2.1 × 10<SUP>-9</SUP>
  we find, based on our thermochemical computations, that the deep O/H
  ratio of Uranus is less than 500 times solar. <BR /> Conclusions:
  Our work shows that the average mole fraction of CO decreases from
  the stratosphere to the troposphere and thus strongly advocates for
  an external source of CO in Uranus. Photochemical modeling of oxygen
  species in the atmosphere of Uranus and more sensitive observations
  are needed to reveal the nature of the external source. <P />Herschel
  is an ESA space observatory with science instruments provided by
  European-led Principal Investigator consortia and with important
  participation from NASA.

---------------------------------------------------------
Title: JUICE: The ESA Mission to Study Habitability of the Jovian
    Icy Moons
Authors: Titov, D.; Barabash, S.; Bruzzone, L.; Dougherty, M.; Duvet,
   L.; Erd, C.; Fletcher, L.; Gladstone, R.; Grasset, O.; Gurvits,
   L.; Hartogh, P.; Hussmann, H.; Iess, L.; Jaumann, R.; Langevin, Y.;
   Palumbo, P.; Piccioni, G.; Wahlund, J. -E.
2014LPICo1774.4035T    Altcode:
  The presentation will give an overview of the ESA's JUICE (JUpiter ICy
  moons Explorer) mission to the Jovian system, its science scenario,
  observation strategy, and the newly selected payload.

---------------------------------------------------------
Title: Line-by-line analysis of Neptune's near-IR spectrum observed
    with Gemini/NIFS and VLT/CRIRES
Authors: Irwin, P. G. J.; Lellouch, E.; de Bergh, C.; Courtin, R.;
   Bézard, B.; Fletcher, L. N.; Orton, G. S.; Teanby, N. A.; Calcutt,
   S. B.; Tice, D.; Hurley, J.; Davis, G. R.
2014Icar..227...37I    Altcode:
  New line data describing the absorption of CH<SUB>4</SUB> and
  CH<SUB>3</SUB>D from 1.26 to 1.71 μm (WKMC-80K, Campargue, A.,
  Wang, L., Mondelain, D., Kassi, S., Bézard, B., Lellouch, E.,
  Coustenis, A., de Bergh, C., Hirtzig, M., Drossart, P. [2012]. Icarus
  219, 110-128) have been applied to the analysis of Gemini-N/NIFS
  observations of Neptune made in 2009 and VLT/CRIRES observations
  made in 2010. The new line data are found to greatly improve the
  fit to the observed spectra and present a considerable advance over
  previous methane datasets. The improved fits lead to an empirically
  derived wavelength-dependent correction to the scattering properties
  of the main observable cloud deck at 2-3 bars that is very similar
  to the correction determined for Uranus' lower cloud using the same
  line dataset by Irwin et al. (Irwin, P.G.J., de Bergh, C., Courtin,
  R., Bézard, B., Teanby, N.A., Davis, G.R., Fletcher, L.N., Orton,
  G.S., Calcutt, S.B., Tice, D., Hurley, J. [2012]. Icarus 220,
  369-382). By varying the abundance of CH<SUB>3</SUB>D in our
  simulations, analysis of the Gemini/NIFS observations leads to
  a new determination of the CH<SUB>3</SUB>D/CH<SUB>4</SUB> ratio
  for Neptune of 3.0-0.9+1.0×10<SUP>-4</SUP>, which is smaller than
  previous determinations, but is identical (to within error) with the
  CH<SUB>3</SUB>D/CH<SUB>4</SUB> ratio of 2.9-0.5+0.9×10<SUP>-4</SUP>
  derived by a similar analysis of Gemini/NIFS observations of Uranus
  made in the same year. Thus it appears that the atmospheres of Uranus
  and Neptune have an almost identical D/H ratio, which suggests that
  the icy planetisimals forming these planets came from the same source
  reservoir, or a reservoir that was well-mixed at the locations of ice
  giant formation, assuming complete mixing between the atmosphere and
  interior of both these planets. VLT/CRIRES observations of Neptune
  have also been analysed with the WKMC-80K methane line database,
  yielding very good fits, with little evidence for missing absorption
  features. The CRIRES spectra indicate that the mole fraction of CO
  at the 2-3 bar level must be substantially less than its estimated
  stratospheric value of 1 × 10<SUP>-6</SUP>, which suggests that the
  predominant source of CO in Neptune's atmosphere is external, through
  the influx of micrometeorites and comets, although these data cannot
  rule out an additional internal source.

---------------------------------------------------------
Title: Colors of Jupiter's large anticyclones and the interaction
    of a Tropical Red Oval with the Great Red Spot in 2008
Authors: Sánchez-Lavega, A.; Legarreta, J.; García-Melendo, E.;
   Hueso, R.; Pérez-Hoyos, S.; Gómez-Forrellad, J. M.; Fletcher, L. N.;
   Orton, G. S.; Simon-Miller, A.; Chanover, N.; Irwin, P.; Tanga, P.;
   Cecconi, M.
2013JGRE..118.2537S    Altcode:
  nature and mechanisms producing the chromophore agents that provide
  color to the upper clouds and hazes of the atmospheres of the giant
  planets are largely unknown. In recent times, the changes in red
  coloration that have occurred in large- and medium-scale Jovian
  anticyclones have been particularly interesting. In late June and
  early July 2008, a particularly color intense tropical red oval
  interacted with the Great Red Spot (GRS) leading to the destruction
  of the tropical red oval and cloud dispersion. We present a detailed
  study of the tropical vortices, usually white but sometimes red, and a
  characterization of their color spectral signatures and dynamics. From
  the spectral reflectivity in methane bands we study their vertical
  cloud structure compared to that of the GRS and BA. Using two spectral
  indices we found a near correlation between anticyclones cloud top
  altitudes and red color. We present detailed observations of the
  interaction of the red oval with the GRS and model simulations of the
  phenomena that allow us to constrain the relative vertical extent of
  the vortices. We conclude that the vertical cloud structure, vertical
  extent, and dynamics of Jovian anticyclones are not the causes of
  their coloration. We propose that the red chromophore forms when
  background material (a compound or particles) is entrained by the
  vortex, transforming into red once inside the vortex due to internal
  conditions, exposure to ultraviolet radiation, or to the mixing of
  two chemical compounds that react inside the vortex, confined by a
  potential vorticity ring barrier.

---------------------------------------------------------
Title: Variation of solar oscillation frequencies in solar cycle 23
    and their relation to sunspot area and number (Corrigendum)
Authors: Jain, R.; Tripathy, S. C.; Watson, F. T.; Fletcher, L.;
   Jain, K.; Hill, F.
2013A&A...560C...1J    Altcode:
  No abstract at ADS

---------------------------------------------------------
Title: Constraining the Depth of Saturn's Zonal Winds by Measuring
    Thermal and Gravitational Signals
Authors: Liu, J.; Schneider, T.; Fletcher, L. N.
2013AGUFM.P21C1748L    Altcode:
  In 2016, NASA's Cassini spacecraft will orbit Saturn in highly
  elliptical orbits and will measure Saturn's gravitational and thermal
  signals at the end of its mission. This provides an opportunity to
  constrain the structure of the zonal winds on the planet. Here we make
  predictions of what Cassini will measure based on dynamical arguments
  that constrain the flow and on already available observations. There
  are strong dynamical constraints on the zonal winds and the associated
  entropy and density distributions on Saturn. Due to Saturn's strong
  internal heat flux, rapid rotation and negligible atmospheric viscosity,
  convective motions are constrained to be primarily along surfaces of
  constant angular momentum; they approximately homogenize entropy along
  the spin axis. Using the assumption that in the interior, entropy is
  homogenized in the direction of the spin axis, but not perpendicular
  to it, we determine the zonal winds and the associated thermal
  and gravitational signals by combing the equation of state of the
  atmosphere, the observed zonal winds at the cloud level, and plausible
  assumptions about the strength of the magnetohydrodynamic (MHD) drag
  that zonal winds experience in the deep interior. A difficulty arises
  because Saturn's observed zonal winds are not well defined because
  the planetary rotation rate is uncertain. Using a range of plausible
  estimates of the rotation rate, we find the observed zonal winds on
  Saturn likely extend deeply into Saturn (to a depth between about
  0.65 RS and 0.85 RS, with Saturn's radius RS, corresponding to 1 Mbar
  and 0.2 Mbar). Material properties of Saturn (the equation of state)
  constrain zonal winds with strengths similar to the cloud levels
  winds to be confined only within the outer few percent of Saturn's
  radius, irrespective of Saturn's rotation rate and the depth of MHD
  drag. The theoretically derived meridional equator-to-pole temperature
  contrasts in thermal wind balance with the zonal winds increase with
  depth and reach 1~2 K at 1 bar and 2~4 K at 5 bar. They would be much
  larger if the zonal winds were shallow, but already available thermal
  observations by Cassini CIRS rule out very shallow flows: zonal winds
  relative to System III rotation rate have to extend deeper than 5000 bar
  (0.97 RS). Otherwise the associated equator-to-pole contrast (O(10K)
  at 1 bar) would exceed the observed values. The gravitational signal
  corresponding to deeply penetrating zonal winds are much larger than
  those that would be associated with shallow zonal winds. Combining the
  thermal signals with the gravitational signals of the zonal winds, the
  penetration depths of the zonal winds relative to different rotation
  rates can be determined by Cassini at the end of its mission.

---------------------------------------------------------
Title: Impact flux on Jupiter: From superbolides to large-scale
    collisions
Authors: Hueso, R.; Pérez-Hoyos, S.; Sánchez-Lavega, A.; Wesley,
   A.; Hall, G.; Go, C.; Tachikawa, M.; Aoki, K.; Ichimaru, M.; Pond,
   J. W. T.; Korycansky, D. G.; Palotai, C.; Chappell, G.; Rebeli, N.;
   Harrington, J.; Delcroix, M.; Wong, M.; de Pater, I.; Fletcher, L. N.;
   Hammel, H.; Orton, G. S.; Tabe, I.; Watanabe, J.; Moreno, J. C.
2013A&A...560A..55H    Altcode:
  Context. Regular observations of Jupiter by a large number of amateur
  astronomers have resulted in the serendipitous discovery of short
  bright flashes in its atmosphere, which have been proposed as being
  caused by impacts of small objects. Three flashes were detected:
  one on June 3, 2010, one on August 20, 2010, and one on September 10,
  2012. <BR /> Aims: We show that the flashes are caused by impacting
  objects that we characterize in terms of their size, and we study the
  flux of small impacts on Jupiter. <BR /> Methods: We measured the light
  curves of these atmospheric airbursts to extract their luminous energy
  and computed the masses and sizes of the objects. We ran simulations
  of impacts and compared them with the light curves. We analyzed the
  statistical significance of these events in the large pool of Jupiter
  observations. <BR /> Results: All three objects are in the 5-20 m size
  category depending on their density, and they released energy comparable
  to the recent Chelyabinsk airburst. Model simulations approximately
  agree with the interpretation of the limited observations. Biases in
  observations of Jupiter suggest a rate of 12-60 similar impacts per
  year and we provide software tools for amateurs to examine the faint
  signature of impacts in their data to increase the number of detected
  collisions. <BR /> Conclusions: The impact rate agrees with dynamical
  models of comets. More massive objects (a few 100 m) should impact
  with Jupiter every few years leaving atmospheric dark debris features
  that could be detectable about once per decade.

---------------------------------------------------------
Title: Models for Temperature and Composition in Uranus from Spitzer,
    Herschel and Ground-Based Infrared through Millimeter Observations
Authors: Orton, G. S.; Fletcher, L. N.; Feuchtgruber, H.; Lellouch,
   E.; Moreno, R.; Encrenaz, T.; Hartogh, P.; Jarchow, C.; Swinyard, B.;
   Moses, J. I.; Burgdorf, M. J.; Hammel, H. B.; Line, M. R.; Sandell,
   G.; Dowell, C. D.
2013AGUFM.P21B1729O    Altcode:
  Photometric and spectroscopic observations of Uranus were combined to
  create self-consistent models of its global-mean temperature profile,
  bulk composition, and vertical distribution of gases. These were
  derived from a suite of spacecraft and ground-based observations
  that includes the Spitzer IRS, and the Herschel HIFI, PACS and SPIRE
  instruments, together with ground-based observations from UKIRT and
  CSO. Observations of the collision-induced absorption of H2 have
  constrained the temperature structure in the troposphere; this was
  possible up to atmospheric pressures of ~2 bars. Temperatures in
  the stratosphere were constrained by H2 quadrupole line emission. We
  coupled the vertical distribution of CH4 in the stratosphere of Uranus
  with models for the vertical mixing in a way that is consistent with
  the mixing ratios of hydrocarbons whose abundances are influenced
  primarily by mixing rather than chemistry. Spitzer and Herschel data
  constrain the abundances of CH3, CH4, C2H2, C2H6, C3H4, C4H2, H2O and
  CO2. At millimeter wavelengths, there is evidence that an additional
  opacity source is required besides the H2 collision-induced absorption
  and the NH3 absorption needed to match the microwave spectrum; this
  can reasonably (but not uniquely) be attributed to H2S. These models
  will be made more mature by consideration of spatial variability from
  Voyager IRIS and more recent spatially resolved imaging and mapping
  from ground-based observatories. The model is of ';programmatic'
  interest because it serves as a calibration source for Herschel
  instruments, and it provides a starting point for planning future
  spacecraft investigations of the atmosphere of Uranus.

---------------------------------------------------------
Title: The Evolution of Hydrocarbon Compounds in Saturn's Stratosphere
    During the 2010 Northern Storm
Authors: Hesman, B. E.; Bjoraker, G. L.; Achterberg, R. K.; Sada,
   P. V.; Jennings, D. E.; Lunsford, A. W.; Sinclair, J.; Romani, P. N.;
   Boyle, R.; Fletcher, L. N.; Irwin, P.
2013AGUFMSM21C2205H    Altcode:
  The massive eruption at 40N (planetographic latitude) in December
  2010 has produced significant and long-lived changes in temperature
  and species abundances in Saturn's northern hemisphere (Hesman et
  al. 2012a, Fletcher et al. 2012). The northern storm region has been
  observed on many occasions between January 2011 and June of 2012 by
  Cassini's Composite Infrared Spectrometer (CIRS). In this time period,
  temperatures in regions referred to as 'beacons' (warm regions in
  the stratosphere at certain longitudes in the storm latitude) became
  significantly warmer than pre-storm values of 140K. In this period
  hydrocarbon emission greatly increased; however, this increased
  emission could not be attributed due to the temperature changes
  alone for many of these species (Hesman et al. 2012b, Bjoraker
  et al 2012). The unique nature of the stratospheric beacons also
  resulted in the detection of ethylene (C<SUB>2</SUB>H<SUB>4</SUB>)
  using CIRS. These beacon regions have also led to the identification
  of rare hydrocarbon species such as C<SUB>4</SUB>H<SUB>2</SUB>
  and C<SUB>3</SUB>H<SUB>4</SUB> in the stratosphere. These species
  are all expected from photochemical processes in the stratosphere,
  however high temperatures, unusual chemistry, or dynamics are
  enhancing these species. The exact cause of these enhancements is
  still under investigation. Ground-based observations were performed
  using the high-resolution spectrometer Celeste in May 2011 to
  confirm the CIRS detection of C<SUB>2</SUB>H<SUB>4</SUB> and to
  study its spectral signatures at higher spectral resolution. In
  order to follow the evolution of its emission further observations
  were performed in July 2011 and March 2012. These observations are
  being used in conjunction with the CIRS observations to investigate
  the source of the approximately 100-fold increase of ethylene in the
  stratospheric beacon. The time evolution of hydrocarbon emission
  from C<SUB>2</SUB>H<SUB>2</SUB>, C<SUB>2</SUB>H<SUB>4</SUB>,
  C<SUB>2</SUB>H<SUB>6</SUB>, C<SUB>3</SUB>H<SUB>4</SUB>, and
  C<SUB>4</SUB>H<SUB>2</SUB> in Saturn's Northern Storm beacon
  regions will be discussed. References: Bjoraker, G., B.E. Hesman,
  R.K. Achterberg, P.N. Romani. 2012, 'The Evolution of Hydrocarbons
  in Saturn's Northern Storm Region,' AAS DPS Conference, Vol. 44,
  #403.05. Fletcher, L.N. et al. 2012, 'The Origin and Evolution of
  Saturn's 2011-2012 Stratospheric Vortex,' Icarus, 221, 560-586. Hesman,
  B.E. et al. 2012a, 'Elusive Ethylene Detected in Saturn's Northern
  Storm Region,' The Astrophysical Journal, 760, 24-30. Hesman, B.E. et
  al. 2012b, 'Ethylene Emission in the Aftermath of Saturn's 2010 Northern
  Storm,' AAS DPS Conference, Vol. 44, #403.06.

---------------------------------------------------------
Title: The optical transmission spectrum of the hot Jupiter HAT-P-32b:
    clouds explain the absence of broad spectral features?
Authors: Gibson, N. P.; Aigrain, S.; Barstow, J. K.; Evans, T. M.;
   Fletcher, L. N.; Irwin, P. G. J.
2013MNRAS.436.2974G    Altcode: 2013MNRAS.tmp.2486G; 2013arXiv1309.6998G
  We report Gemini-North Gemini Multi-Object Spectrograph observations
  of the inflated hot Jupiter HAT-P-32b during two primary transits. We
  simultaneously observed two comparison stars and used differential
  spectrophotometry to produce multiwavelength light curves. `White'
  light curves and 29 `spectral' light curves were extracted for each
  transit and analysed to refine the system parameters and produce
  transmission spectra from 520 to 930 nm in ≈14 nm bins. The light
  curves contain time-varying white noise as well as time-correlated
  noise, and we used a Gaussian process model to fit this complex noise
  model. Common mode corrections derived from the white light-curve fits
  were applied to the spectral light curves which significantly improved
  our precision, reaching typical uncertainties in the transit depth of
  ∼2 × 10<SUP>-4</SUP>, corresponding to about half a pressure scale
  height. The low-resolution transmission spectra are consistent with a
  featureless model, and we can confidently rule out broad features larger
  than about one scale height. The absence of Na/K wings or prominent
  TiO/VO features is most easily explained by grey absorption from clouds
  in the upper atmosphere, masking the spectral features. However, we
  cannot confidently rule out clear atmosphere models with low abundances
  (∼10<SUP>-3</SUP> solar) of TiO, VO or even metal hydrides masking
  the Na and K wings. A smaller scale height or ionization could also
  contribute to muted spectral features, but alone are unable to account
  for the absence of features reported here.

---------------------------------------------------------
Title: Europa's Atmosphere and Aurora: Recent Advances from HST-STIS
    and Plans for Plume Searches with JUICE-UVS
Authors: Retherford, K. D.; Gladstone, R.; Roth, L.; McGrath, M. A.;
   Saur, J.; Feldman, P. D.; Steffl, A. J.; Strobel, D. F.; Greathouse,
   T. K.; Spencer, J. R.; Bagenal, F.; Fletcher, L. N.; Eterno, J. S.
2013AGUFM.P53A1838R    Altcode:
  Space Telescope Imaging System (STIS) images of Europa's neutral oxygen
  130.4 nm and 135.6 nm emissions contain a wealth of information about
  the molecular oxygen atmosphere, discovered using previous Hubble far-UV
  observations. Europa's magnetospheric plasma interaction generates
  auroral emissions, which exhibit a morphology that has been difficult
  to interpret. Recent observations in Nov. &amp; Dec. 2012 allow a new
  understanding of how Jupiter's magnetic field orientation and relation
  to the plasma sheet control the emission variability, yet explanations
  for this general behavior, including the likely role of ocean-induced
  magnetic fields and possible local atmospheric density enhancements,
  remain incomplete (cf. Roth et al. this meeting). NASA's Ultraviolet
  Spectrograph (UVS) instrument contribution to the ESA-led Jupiter
  Icy Moons Explorer (JUICE) mission will obtain excellent imaging of
  these atmospheric and auroral emissions from Europa during two flybys
  currently planned, with the objective of investigating these and other
  unanswered questions. UVS's stellar occultation technique will be used
  to characterize Europa's atmosphere structure and composition and to
  also search for local enhancements created by plumes. This stellar
  occultation technique, demonstrated by Cassini-UVIS at Enceladus, has
  the benefit of being useful at relatively large distances (several 10's
  of Jupiter radii) as well as during the Europa flyby sequences (several
  10's of Europa radii). A robust search for plumes is planned in JUICE's
  first year at Jupiter to provide a roughly 30-degree grid of global
  coverage, followed by focused targeting of likely plumes/active-regions
  during early and late stages of the flyby sequences. High spatial
  resolution limb imaging is also planned near closest approaches, which
  could directly image plume gases in a manner analogous with plume
  aurora imaging of Io. A UV spectrograph on the planned Europa Clipper
  mission could perform an even more robust search for such currently
  active geological sites with connectivity to subsurface liquid water.

---------------------------------------------------------
Title: Photochemistry in Saturn's Ring-Shadowed Atmosphere: Of
    Venetian Blinds, Atmospheric Molecules and Observations
Authors: Edgington, S. G.; Atreya, S. K.; Wilson, E. H.; Baines,
   K. H.; West, R. A.; Bjoraker, G. L.; Fletcher, L. N.; Momary, T.
2013AGUFMSM21C2204E    Altcode:
  Cassini has been orbiting Saturn for over nine years. During this epoch,
  the ring shadow has moved from covering a relatively large portion of
  the northern hemisphere to covering a large swath south of the equator
  and continues to move southward. At Saturn Orbit Insertion in 2004,
  the ring plane was inclined by ~24 degrees relative to the Sun-Saturn
  vector. The projection of the B-ring onto Saturn reached as far as 40N
  along the central meridian (~52N at the terminator). At its maximum
  extent, the ring shadow can reach as far as 48N/S (~58N/S at the
  terminator). The net effect is that the intensity of both ultraviolet
  and visible sunlight penetrating into any particular latitude will
  vary depending on both Saturn's axis relative to the Sun and the
  optical thickness of each ring system. In essence, the rings act like
  venetian blinds. Our previous work [1] examined the variation of the
  solar flux as a function of solar inclination, i.e. ~8 year season at
  Saturn. Here, we report on the impact of the oscillating ring shadow
  on the photolysis and production rates of hydrocarbons in Saturn's
  stratosphere and upper troposphere, including acetylene, ethane,
  propane, and benzene. Beginning with methane, we investigate the impact
  on production and loss rates of the long-lived photochemical products
  leading to haze formation are examined at several latitudes over a
  Saturn year. Similarly, we assess its impact on phosphine abundance,
  a disequilibrium species whose presence in the upper troposphere is a
  tracer of convection processes in the deep atmosphere. Comparison to
  the corresponding rates for the clear atmosphere and for the case of
  Jupiter, where the variation of solar insolation due to tilt is known
  to be insignificant (~3 degree inclination), will be presented. We
  will present our ongoing analysis of Cassini's CIRS, UVIS, and VIMS
  datasets that provide an estimate of the evolving haze content of the
  northern hemisphere and we will begin to assess the implications for
  dynamical mixing. [1] Edgington, S.G., et al., 2012. Photochemistry
  in Saturn's Ring Shadowed Atmosphere: Modeling, Observations, and
  Preliminary Analysis. Bull. American. Astron. Soc., 38, 499 (#11.23).

---------------------------------------------------------
Title: Changes in Saturn's Zonal-Mean Tropospheric Structure After
    the 2010-2011 Northern Storm
Authors: Achterberg, R. K.; Gierasch, P. J.; Conrath, B. J.; Fletcher,
   L. N.; Hesman, B. E.; Bjoraker, G. L.; Flasar, F.
2013AGUFMSM21C2203A    Altcode:
  In early December 2010, a large convective storm erupted at
  approximately 40°N planetographic latitude on Saturn, lasting
  until early July 2011 (Sánchez-Lavega et al. 2012, Icarus,
  220, 561-576). We use far-infrared (20μm - 200μm) data from the
  Composite Infrared Spectrometer (CIRS) on the Cassini spacecraft to
  determine the zonal-mean temperature and hydrogen para-fraction in
  Saturn's upper troposphere between approximately 200 and 800 mbar from
  observations taken before and after the large northern hemisphere storm
  in 2010-2011. During the storm, the latitude band between approximately
  25°N and 45°N (planetographic latitude) warmed by about 3 K, while the
  hydrogen para-fraction decreased by about 0.04 over the same latitudes,
  at pressures greater than about 300 mbar. These changes occurred over
  the same latitude range as the disturbed cloud band seen in visible
  images. The decrease in hydrogen para-fraction is consistent with a
  strong convective plume advecting low para-fraction hydrogen upward
  from the several bar level, where the equilibrium para-fraction is
  0.25, and the subsequent mixing of the low para-fraction hydrogen with
  the ambient atmosphere. Heat released from water condensation in the
  plume, or the conversion of ortho-hydrogen to para-hydrogen may then
  explain the observed temperature increase. The changes observed in
  the zonal-mean temperatures are roughly consistent with the changes
  in zonal winds seen by Sayanagi et al. (2013, Icarus, 223, 460-478)
  assuming geostrophic balance.

---------------------------------------------------------
Title: Oxygen Compounds in Saturn's Stratosphere During the 2010
    Northern Storm
Authors: Bjoraker, G. L.; Hesman, B. E.; Achterberg, R. K.; Jennings,
   D. E.; Romani, P. N.; Fletcher, L. N.; Irwin, P.
2013AGUFMSM21C2206B    Altcode:
  The massive storm at 40N on Saturn that began in December 2010 has
  produced significant and long-lived changes in temperature and species
  abundances in the stratosphere throughout the northern hemisphere
  (Hesman et al. 2012a, Fletcher et al. 2012). The northern storm
  region has been observed on many occasions between January 2011 and
  January 2013 by Cassini's Composite Infrared Spectrometer (CIRS). In
  this time period, temperatures in regions referred to as 'beacons'
  (warm regions in the stratosphere at certain longitudes in the storm
  latitude) became significantly warmer than pre-storm values of 140K,
  peaking at 220K in May 2011 followed by gradual cooling. Hydrocarbon
  emission greatly increased over pre-storm values and then slowly decayed
  as the beacon cooled. Radiative transfer modeling has revealed that
  this increased emission is due to enhanced gas abundances for many
  of these species, rather than simply due to the temperature changes
  alone (Hesman et al. 2012b, Bjoraker et al 2012). In order to build a
  comprehensive picture of the changes to the stratosphere due to the
  2010 northern storm we are now investigating the oxygen compounds
  in Saturn's stratosphere to determine if similar changes in these
  species were measured. The time evolution of stratospheric CO2 and
  H2O abundances in the beacon regions throughout 2011 and 2012 will be
  presented and compared with pre-storm measurements made in 2010.

---------------------------------------------------------
Title: Ground-Based Observations of the Aftermath of the 2010-2011
    Great Northern Springtime Storm in Saturn (Invited)
Authors: Orton, G. S.; Fletcher, L. N.; Fouchet, T.; Fujiyoshi, T.;
   Greathouse, T. K.; Momary, T.; Yanamandra-Fisher, P. A.
2013AGUFMSM14A..06O    Altcode:
  For the first time, a suite of ground-based and spacecraft instruments
  were available to detect and characterize one of the rare giant
  convective storms erupting in Saturn's atmosphere. The storm that
  erupted on 2010 December 5 created an immense thermal and chemical
  perturbation of the atmosphere. Most of the perturbation of the visible
  cloud system had abated within a year of the initial eruption, but
  changes to the atmosphere were evident at thermal infrared wavelengths,
  and they continue to the present. Here we review the observations from
  ground-based stations that include NASA's Infrared Telescope Facility
  (IRTF) and the Subaru Telescope, both at the summit of Mauna Kea, as
  well as observations from ESO's Very Large Telescope. Evident in the
  5-μm spectral window was the clearing of nearly all clouds around and
  above the 3-bar level of the atmosphere at the latitude of the primary
  storm. In the intervening two years, imaging in the same window by
  the IRTF NSFCam2 instrument shows that the cleared region remains
  prominent and is filling in with a pre-storm cloud cover only very
  slowly. Most unexpected was the generation of a stratospheric vortex
  of high temperatures, 'the beacon' (Fletcher et al. 2011 Science 332,
  1413). This phenomenon also continues more than two years later and has
  been tracked using several mid-infrared imaging instruments: VISIR at
  the VLT, COMICS at Subaru, and MIRSI at the IRTF using moderate-band
  filters. More precise determination of its vertical distribution was
  made using the University of Texas Echelon Cross Echelle Spectrograph
  (TEXES) at the IRTF, targeting specific lines of CH4 and the H2
  quadrupole. All of these measurements, taken in concert, show that
  the heated region of the stratosphere is diminishing in amplitude,
  expanding in longitude and slowly sinking in altitude.

---------------------------------------------------------
Title: The Impulsive Phase in Solar Flares: Recent Multi-wavelength
    Results and their Implications for Microwave Modeling and Observations
Authors: Fletcher, Lyndsay; Simoes, Paulo J. A.
2013arXiv1311.7175F    Altcode:
  This short paper reviews several recent key observations of the
  processes occurring in the lower atmosphere (chromosphere and
  photosphere) during flares. These are: evidence for compact and
  fragmentary structure in the flare chromosphere, the conditions in
  optical flare footpoints, step-like variations in the magnetic field
  during the flare impulsive phase, and hot, dense 'chromospheric'
  footpoints. The implications of these observations for microwaves are
  also discussed.

---------------------------------------------------------
Title: Implosion of Coronal Loops during the Impulsive Phase of a
    Solar Flare
Authors: Simões, P. J. A.; Fletcher, L.; Hudson, H. S.; Russell,
   A. J. B.
2013ApJ...777..152S    Altcode: 2013arXiv1309.7090S
  We study the relationship between implosive motions in a solar
  flare, and the energy redistribution in the form of oscillatory
  structures and particle acceleration. The flare SOL2012-03-09T03:53
  (M6.4) shows clear evidence for an irreversible (stepwise) coronal
  implosion. Extreme-ultraviolet (EUV) images show at least four
  groups of coronal loops at different heights overlying the flaring
  core undergoing fast contraction during the impulsive phase of the
  flare. These contractions start around a minute after the flare onset,
  and the rate of contraction is closely associated with the intensity
  of the hard X-ray and microwave emissions. They also seem to have
  a close relationship with the dimming associated with the formation
  of the coronal mass ejection and a global EUV wave. Several studies
  now have detected contracting motions in the corona during solar
  flares that can be interpreted as the implosion necessary to release
  energy. Our results confirm this, and tighten the association with
  the flare impulsive phase. We add to the phenomenology by noting
  the presence of oscillatory variations revealed by Geostationary
  Operational Environmental Satellite soft X-rays (SXR) and spatially
  integrated EUV emission at 94 and 335 Å. We identify pulsations
  of ≈60 s in SXR and EUV data, which we interpret as persistent,
  semi-regular compressions of the flaring core region which modulate
  the plasma temperature and emission measure. The loop oscillations,
  observed over a large region, also allow us to provide rough estimates
  of the energy temporarily stored in the eigenmodes of the active-region
  structure as it approaches its new equilibrium.

---------------------------------------------------------
Title: Science goals and concepts of a Saturn probe for the future
    L2/L3 ESA call
Authors: Schmider, F. -X.; Mousis, O.; Fletcher, L. N.; Altwegg, K.;
   André, N.; Blanc, M.; Coustenis, A.; Gautier, D.; Geppert, W. D.;
   Guillot, T.; Irwin, P.; Lebreton, J. -P.; Marty, B.; Sánchez-Lavega,
   A.; Waite, J. H.; Wurz, P.
2013sf2a.conf...65S    Altcode:
  Comparative studies of the elemental enrichments and isotopic abundances
  measured on Saturn can provide unique insights into the processes
  at work within our planetary system and are related to the time and
  location of giant planet formation. In situ measurements via entry
  probes remain the only reliable, unambiguous method for determining
  the atmospheric composition from the thermosphere to the deep
  cloud-forming regions of their complex weather layers. Furthermore,
  in situ experiments can reveal the meteorological properties of
  planetary atmospheres to provide “ground truth” for orbital remote
  sensing. Following the orbital reconnaissance of the Galileo and Cassini
  spacecraft, and the single-point in situ measurement of the Galileo
  probe to Jupiter, we believe that an in situ measurement of Saturn's
  atmospheric composition should be an essential element of ESA's future
  cornerstone missions, providing the much-needed comparative planetology
  to reveal the origins of our outer planets. This quest for understanding
  the origins of our solar system and the nature of planetary atmospheres
  is in the heart of ESA's Cosmic Vision, and has vast implications for
  the origins of planetary systems around other stars.

---------------------------------------------------------
Title: The Ultraviolet Spectrograph (UVS) on ESA’s JUICE Mission
Authors: Gladstone, Randy; Retherford, K.; Steffl, A.; Eterno, J.;
   Davis, M.; Versteeg, M.; Greathouse, T.; Araujo, M.; Walther, B.;
   Persson, K.; Persyn, S.; Dirks, G.; McGrath, M.; Feldman, P.; Bagenal,
   F.; Spencer, J.; Schindhelm, R.; Fletcher, L.
2013DPS....4521104G    Altcode:
  The Jupiter Icy Moons Explorer (JUICE) was selected in May 2012 as
  the first L-class mission of ESA’s Cosmic Vision Program. JUICE will
  launch in 2022 on a 7.6-year journey to the Jovian system, including
  a Venus and multiple Earth gravity assists, before entering Jupiter
  orbit in January 2030. JUICE will study the entire Jovian system for
  3.5 years, concentrating on Europa, Ganymede, and Callisto, with the
  last 10 months spent in Ganymede orbit. The Ultraviolet Spectrograph
  (UVS) on JUICE was jointly selected by NASA and ESA as part of its
  ~130 kg payload of 11 scientific instruments. UVS is the fifth in a
  series of successful ultraviolet imaging spectrographs (Rosetta-Alice,
  New Horizons Pluto-Alice, LRO-LAMP) and is largely based on the
  most recent of these, Juno-UVS. It observes photons in the 55-210
  nm wavelength range, at moderate spectral and spatial resolution
  along a 7.5-degree slit. A main entrance “airglow port” (AP) is
  used for most observations (e.g., airglow, aurora, surface mapping,
  and stellar occultations), while a separate “solar port” (SP)
  allows for solar occultations. Another aperture door, with a small
  hole through the centre, is used as a “high-spatial-resolution
  port” (HP) for detailed observations of bright targets. Time-tagging
  (pixel list mode) and programmable spectral imaging (histogram mode)
  allow for observational flexibility and optimal data management. As on
  Juno-UVS, the effects of penetrating electron radiation on electronic
  parts and data quality are substantially mitigated through contiguous
  shielding, filtering of pulse height amplitudes, management of high
  voltage settings, and careful use of radiation-hard, flight-tested
  parts. The science goals of UVS are to: 1) explore the atmospheres,
  plasma interactions, and surfaces of the Galilean satellites; 2)
  determine the dynamics, chemistry, and vertical structure of Jupiter’s
  upper atmosphere from equator to pole; and 3) investigate the Jupiter-Io
  connection by quantifying energy and mass flow in the Io atmosphere,
  neutral clouds, and torus. Here we present the salient features of
  the UVS instrument and describe the science we plan to address.

---------------------------------------------------------
Title: Properties of Slowly Moving Thermal Waves in Saturn from
    Cassini CIRS and Ground-Based Thermal Observations from 2003 to 2009
Authors: Orton, Glenn S.; Fletcher, L. N.; Flasar, F.; Achterberg,
   R. K.; Yanamandra-Fisher, P. A.; Lewis, M.; Fujiyoshi, T.; Bell, J.;
   Christian, J.; Brown, S. K.
2013DPS....4531207O    Altcode:
  Hemispherical maps of Saturn’s atmosphere made both by Cassini’s
  Composite Infrared Spectrometer (CIRS, 7-1000 µm) and ground-based
  mid-infrared observations (7-25 µm) were surveyed for the presence and
  properties of zonal thermal waves and their variability in time. The
  most inclusive CIRS surveys, FIRMAPs (15 cm-1 spectral resolution),
  covered the planet from the equator to either north or south pole,
  sweeping through the latitude range while the planet rotated beneath
  over its ~10-hour rotation. Ground-based observations were made at
  the Infrared Telescope Facility using the MIRSI instrument, the Very
  Large Telescope using VISIR and the Subaru Telescope using COMICS. We
  sampled spectral ranges dominated both by upper-tropospheric emission
  (80-200 mbar) and by stratospheric emission (0.5-3 mbar). We examined
  data that were taken between 2003 and Saturn’s spring equinox
  in 2009. During this time, the strongest waves were found between
  planetographic latitudes of 30° - 45°S and 0° - 30°N. Some
  low-wavelength components cover all 360° in longitude, similar to
  the slowly moving thermal waves in Jupiter’s atmosphere, but the
  strongest waves were found in “trains” that covered less than
  180°. In 2005, tropospheric waves had a mean peak-to-peak variance
  that was the equivalent of temperature variability of about 1 K. Between
  2005 and 2007, they had subsided to about 0.5 K. During and after 2008,
  they soared to over 3 K. During this entire period, similar waves in the
  northern hemisphere were never larger than 0.8 K. In the stratosphere,
  waves followed a similar time sequence, with southern hemisphere
  waves in 2005 reaching amplitudes as high as 3.5 K in brightness
  temperature, subsequently decreasing, then growing in 2008-2009 to
  over 5 K. Stratospheric waves in the northern hemisphere were nearly
  constant ~2 K, but with an instance of 6 K at one epoch in 2008. We
  were able to track the phase of some of the waves in the southern
  hemisphere, which moved about 0.5° of longitude per day retrograde
  with respect to System III. The phase of tropospheric and stratospheric
  waves appeared to be highly correlated with one another with little
  offset in longitudes but not with positions of atmospheric storms.

---------------------------------------------------------
Title: IRTF/TEXES observations of Saturn’s stratospheric beacon
Authors: Fouchet, Thierry; Greathouse, T. K.; Richter, M. J.; Lacy,
   J.; Fletcher, L.; Spiga, A.
2013DPS....4550907F    Altcode:
  On December 5th, 2010, a giant convective storm erupted in Saturn’s
  Northern Hemisphere as each Saturnian year at least since 1876. For
  the first time, a huge thermal and chemical stratospheric disturbance
  associated with this large convective event was detected from
  ground-based and Cassini observations (Fletcher et al. 2011). This
  stratospheric disturbance is named the beacon. Here, we present
  high spectral resolution observations of the beacon obtained by the
  Texas Echelon Cross Echelle Spectrograph (TEXES) mounted on the
  IRTF during 6 nights from July 15th, 2011 to July 20th, 2011. We
  targeted several different CH4 lines between 1230 and 1280 cm-1,
  probing the stratospheric temperature between 5 hPa and 0.05 hPa,
  and the H2 S(1) quadrupolar and collision-induced lines at 587 cm-1,
  probing the stratospheric temperature between 150 hPa and 5 hPa. The
  stratospheric temperatures are retrieved from the dataset using a
  forward radiative model coupled with a constrained linear inverse
  method. Within the core of the beacon the maximum temperature inferred
  from the data is 178K at 40°N, hence about 50K warmer than the mean
  temperature measured before the occurrence of the storm. However,
  the TEXES data unambiguously demonstrate that this warming is not
  vertically homogeneous but rather confined in a specific pressure
  range between 1-5 hPa, overhung by a cold layer between 0.1 and 1
  hPa. This vertical behavior is evident from the CH4 line spectral
  profiles with the core of the lines in absorption and the wings in
  emission. Moreover, our data demonstrate that the altitude of the
  local temperature maximum increases northwards. We will present how
  this thermal structure can help deciphering the stratospheric heating
  sources. On the western side of the beacon, the stratospheric heating
  is concentrated at lower pressures, hence higher altitudes, than within
  the beacon, between 0.1 and 0.01 hPa. We interpret this structure as
  being caused by convective motions within the beacon, and westward
  advection associated with a vertical shear of stratospheric zonal winds.

---------------------------------------------------------
Title: Multi-wavelength Observations of Neptune’s Atmosphere
Authors: de Pater, Imke; Fletcher, L.; Luszcz-Cook, S.; deBoer, D.;
   Butler, B.; Orton, G.; Sitko, M.; Hammel, H.
2013DPS....4531220D    Altcode:
  We conducted a multi-wavelength observing campaign on Neptune between
  June and October, 2003. We used the 10-m Keck telescope at near- and
  mid-infrared wavelengths and the VLA at radio wavelengths. Near infrared
  images were taken in October 2003 in broad- and narrow-band filters
  between 1 and 2.5 micron, using the infrared camera NIRC2 coupled to
  the Keck Adaptive Optics system. At these wavelengths we detect sunlight
  reflected off clouds in the upper troposphere and lower stratosphere. As
  shown by various authors before, bright bands of discrete cloud
  features are visible between 20°S and 50°S and near 30°N, as well
  as several distinct bright cloud features near 70°S, and the south
  polar “dot”. Mid-infrared images were taken on September 5 and 6
  (2003) using the Keck LWS system in atmospheric windows at 8, 8.9, 10.7,
  11.7, 12.5, 17.65, 18.75 and 22 micron. At these wavelengths we detect
  thermal emission from Neptune’s stratosphere due to the presence of
  hydrocarbons, and from near the tropopause due to collision induced
  opacity by hydrogen. At all wavelengths the South polar region stands
  out as a bright spot. At 17 - 22 micron also the equatorial region is
  slightly enhanced in intensity. These characteristics are consistent
  with later imaging at similar wavelengths (Hammel et al. 2007; Orton et
  al. 2007). Microwave images were constructed from NRAO VLA data between
  0.7 and 6.0 cm. At these wavelengths depths of several up to &gt;50
  bar are probed. An increase in brightness indicates decreased opacity
  of absorbers (e.g., NH3, H2S), since under such circumstances deep,
  and hence warm levels (adiabatic temperature-pressure profile), will
  be probed. The multi-wavelength observing campaign in 2003 was focused
  on obtaining images that probe different altitudes in Neptune’s
  atmosphere. Indeed, this set of data probes altitudes from about 0.1
  mbar down to ~50 bar, and hence can be used to constrain the global
  atmospheric circulation in Neptune’s atmosphere. At the meeting we
  will show our results and interpretation of the findings.

---------------------------------------------------------
Title: Hydrocarbon and oxygen photochemistry on Uranus as revealed
    from Spitzer/IRS observations
Authors: Moses, Julianne I.; Orton, G. S.; Fletcher, L. N.; Mainzer,
   A. K.; Hines, D. C.; Hammel, H. B.; Martin-Torres, J.; Burgdorf, M.;
   Merlet, C.; Line, M. R.; Poppe, A.
2013DPS....4531213M    Altcode:
  Due to the very low atmospheric temperatures and hydrocarbon column
  abundances on Uranus, the planet appears very faint at mid-infrared
  wavelengths, making determinations of atmospheric composition
  difficult. The Spitzer Space Telescope Infrared Spectrometer (IRS)
  is two orders of magnitude more sensitive than previous space-based
  instruments, favoring the detection of faint molecular emission
  features from Uranus’ atmosphere (e.g., Burgdorf et al. 2006,
  Icarus 184, 634). Global-average Spitzer/IRS spectra acquired just
  days after the planet’s 2007 northern vernal equinox (Orton et
  al. 2013, manuscript submitted to Icarus) exhibit molecular emission
  features from CH4, C2H2, C2H6, C3H4, C4H2, and CO2 in Uranus’
  stratosphere. We use these Spitzer/IRS observations to constrain new
  1-D photochemical models for Uranus. Although the upper-stratospheric
  methane abundance is well determined from the observations, there is a
  range of model parameter space in terms of eddy diffusion coefficients
  Kzz and tropopause methane relative humidities that can reproduce
  the observed methane emission. However, all such models possess Kzz
  values that are considerably smaller than those on the other giant
  planets; the observations show no convincing evidence for significant
  changes in low-latitude Kzz values with time since the Voyager era. We
  highlight the differences in atmospheric chemistry and mixing between
  Uranus and the other giant planets (including the reasons behind the
  lower C2H6/C2H2 ratio on Uranus), discuss the implications of the
  observed C4H2 emission with respect to the vapor pressure of C4H2 over
  diacetylene ice at low temperatures, and summarize the implications
  with respect to the influx of external oxygen compounds and their
  corresponding upper-atmospheric haze components. This research was
  supported by the NASA Planetary Atmospheres program.

---------------------------------------------------------
Title: The origin of CO in the stratosphere of Uranus
Authors: Cavalié, Thibault; Moreno, R.; Lellouch, E.; Hartogh,
   P.; Venot, O.; Orton, G. S.; Jarchow, C.; Encrenaz, T.; Selsis, F.;
   Hersant, F.; Fletcher, L. N.
2013DPS....4531214C    Altcode:
  Oxygen-rich deep interiors of the Giant Planets cannot explain the
  discovery of H2O and CO2 in the stratospheres of the Giant Planets
  by Feuchtgruber et al. (1997) because these species are trapped by
  condensation around their tropopause levels (except CO2 in Jupiter and
  Saturn). Therefore, several sources in the direct or far environment
  of the Giant Planets have been proposed: icy rings and/or satellites,
  interplanetary dust particles and large comet impacts. CO does not
  condense at the tropopauses of Giant Planets, so that oxygen-rich
  interiors are a valid source. An internal component has indeed been
  observed in the vertical profile of CO in Jupiter (Bézard et al., 2002)
  and in Neptune (Lellouch et al., 2005), while an upper limit has been
  set on its magnitude by for Saturn (Cavalié et al., 2009). In addition
  to interiors, large comets seem to be the dominant external source, as
  shown by various studies: Bézard et al. (2002) for Jupiter, Cavalié et
  al. (2010) for Saturn and Lellouch et al. (2005) for Neptune. The first
  detection of CO in Uranus was obtained by Encrenaz et al. (2004) from
  fluorescent emission at 4.7 microns. Assuming a uniform distribution,
  a mixing ratio of 2x10-8 was derived. Despite this first detection
  almost a decade ago, the situation has remained unclear ever since. In
  this paper, we will present the first submillimeter detection of
  CO in Uranus, carried out with Herschel in 2011-2012. Using a simple
  diffusion model, we review the various possible sources of CO (internal
  and external). We show that CO is mostly external. We also derive
  an upper limit for the internal source. And with the thermochemical
  model of Venot et al. (2012), adapted to the interior of Uranus, we
  derive an upper limit on its deep O/H ratio from it. Acknowledgments
  T. Cavalié acknowledges support from CNES and the European Research
  Council (Starting Grant 209622: E3ARTHs). References Bézard et
  al., 2002. Icarus, 159, 95-111. Cavalié et al., 2009. Icarus, 203,
  531-540. Cavalié et al., 2010. A&amp;A, 510, A88. Encrenaz et al.,
  2004. A&amp;A, 413, L5-L9. Feuchtgruber et al., 1997. Nature, 389,
  159-162. Lellouch et al., 2005. A&amp;A, 430, L37-L40. Venot et al.,
  2012. A&amp;A, 546, A43.

---------------------------------------------------------
Title: Oxygen Compounds in Saturn’s Stratosphere During the 2010
    Northern Storm
Authors: Hesman, Brigette E.; Bjoraker, G. L.; Achterberg, R. K.;
   Jennings, D. E.; Romani, P. N.; Fletcher, L. N.; Irwin, P. G.
2013DPS....4531212H    Altcode:
  The massive eruption at 40N (planetographic latitude) in December
  2010 has produced significant and long-lived changes in temperature
  and species abundances in Saturn’s northern hemisphere (Hesman et
  al. 2012a, Fletcher et al. 2012). The northern storm region has been
  observed on many occasions between January 2011 and June of 2012 by
  Cassini’s Composite Infrared Spectrometer (CIRS). In this time period,
  temperatures in regions referred to as “beacons” (warm regions in
  the stratosphere at certain longitudes in the storm latitude) became
  significantly warmer than pre-storm values of 140K. In this period
  hydrocarbon emission greatly increased however this increased emission
  could not be attributed due to the temperature changes alone for many
  of these species (Hesman et al. 2012b, Bjoraker et al 2012). In order
  to build a comprehensive picture of the changes to the stratosphere
  due to the 2010 northern storm we are now investigating the oxygen
  compounds in Saturn’s stratosphere to determine if similar changes
  in these species were measured. The time evolution of stratospheric
  CO2 and H2O abundances in the beacon regions throughout 2011 and
  2012 will be presented. References: Bjoraker, G., B.E. Hesman,
  R.K. Achterberg, P.N. Romani. 2012, “The Evolution of Hydrocarbons
  in Saturn’s Northern Storm Region,” AAS DPS Conference, Vol. 44,
  #403.05. Fletcher, L.N. et al. 2012, “The Origin and Evolution
  of Saturn’s 2011-2012 Stratospheric Vortex,” Icarus, 221,
  560-586. Hesman, B.E. et al. 2012a, “Elusive Ethylene Detected
  in Saturn’s Northern Storm Region,” The Astrophysical Journal,
  760, 24-30. Hesman, B.E. et al. 2012b, “Ethylene Emission in the
  Aftermath of Saturn’s 2010 Northern Storm,” AAS DPS Conference,
  Vol. 44, #403.06.

---------------------------------------------------------
Title: Photochemistry in Saturn’s Ring-Shadowed Atmosphere:
    Venetian Blinds, Atmospheric Molecules and Observations
Authors: Edgington, Scott G.; Atreya, S. K.; Wilson, E. H.; Baines,
   K. H.; West, R. A.; Bjoraker, G. L.; Fletcher, L. N.; Momary, T.
2013DPS....4531215E    Altcode:
  Cassini has been orbiting Saturn for over nine years. During this
  epoch, the ring shadow has moved from covering a relatively large
  portion of the northern hemisphere to covering a large swath south of
  the equator and continues to move southward. At Saturn Orbit Insertion
  in 2004, the ring plane was inclined by ~24 degrees relative to the
  Sun-Saturn vector. The projection of the B-ring onto Saturn reached as
  far as 40N along the central meridian 52N at the terminator). At its
  maximum extent, the ring shadow can reach as far as 48N/S 58N/S at the
  terminator). The net effect is that the intensity of both ultraviolet
  and visible sunlight penetrating into any particular latitude will
  vary depending on both Saturn’s axis relative to the Sun and the
  optical thickness of each ring system. In essence, the rings act like
  venetian blinds. Our previous work [1] examined the variation of the
  solar flux as a function of solar inclination, i.e. ~8 year season at
  Saturn. Here, we report on the impact of the oscillating ring shadow
  on the photolysis and production rates of hydrocarbons in Saturn’s
  stratosphere and upper troposphere, including acetylene, ethane,
  propane, and benzene. Beginning with methane, we investigate the impact
  on production and loss rates of the long-lived photochemical products
  leading to haze formation are examined at several latitudes over a
  Saturn year. Similarly, we assess its impact on phosphine abundance,
  a disequilibrium species whose presence in the upper troposphere is
  a tracer of convection processes in the deep atmosphere. Comparison
  to the corresponding rates for the clear atmosphere and for the case
  of Jupiter, where the variation of solar insolation due to tilt is
  known to be insignificant 3 degree inclination), will be presented. We
  will present our ongoing analysis of Cassini’s CIRS, UVIS, and VIMS
  datasets that provide an estimate of the evolving haze content of the
  northern hemisphere and we will begin to assess the implications for
  dynamical mixing. [1] Edgington, S.G., et al., 2012. Photochemistry
  in Saturn’s Ring Shadowed Atmosphere: Modeling, Observations, and
  Preliminary Analysis. Bull. American. Astron. Soc., 38, 499 (#11.23).

---------------------------------------------------------
Title: Neptune Clouds and Methane, from Ground-Based Visible and
    Near-Infrared Spectroscopy with Adaptive Optics
Authors: Tice, D. S.; Irwin, P. G. J.; Houghton, R. W. C.; Fletcher,
   L. N.; Clarke, F.; Hurley, J.; Thatte, N.; Tecza, M.
2013EPSC....8..549T    Altcode:
  Observations of Neptune were made in June/July 2012 with the SWIFT
  integral field spectrometer at the Palomar Observatory's 200-inch
  Hale Telescope. Spectral resolutions for observations between 0.65
  μm and 1.0 μm were R ≥ 3250. Palomar's PALM-3000 adaptive optics
  system enabled images of the full Neptunian disc to be recorded at a
  spatial scale of 0.08"·pixel^-1 with a seeing of approximately 0.30"
  - 0.40". Retrievals of cloud properties and methane abundance in
  the highly dynamic atmosphere were obtained with the general-purpose
  retrieval tool, NEMESIS. The short wavelengths of the observations
  allowed for good characterisation of the scattering particles' optical
  properties in the many cloud and haze layers of the upper Neptunian
  atmosphere. A region of relatively low methane absorption and high
  collision-induced hydrogen quadrupole absorption at 825 nm further
  constrains spectral properties of clouds as distinguished from those
  of methane absorption.

---------------------------------------------------------
Title: The thermal structure of the 2011 Saturn's stratospheric
    beacon mapped with TEXES/IRTF
Authors: Fouchet, T.; Greathouse, T.; Richter, M.; Lacy, J.; Fletcher,
   L.; Guerlet, S.; Spiga, A.
2013EPSC....8..381F    Altcode:
  We present spectral observations of Saturn's stratosphere obtained
  in 2011 by the TEXES imaging spectrometer mounted on the IRTF. These
  observations allowed us to determine the thermal structure of the
  stratospheric disturbance induced by the 2010 Great White Storm.

---------------------------------------------------------
Title: Saturn northern hemisphere's atmosphere and polar hexagon
    in 2013
Authors: Delcroix, M.; Yanamandra-Fisher, P.; Fischer, G.; Fletcher,
   L. N.; Sayanagi, K. M.; Barry, T.
2013EPSC....8.1067D    Altcode:
  In 2013, two years after the dramatic events of the Great White Spot
  (GWS), amateur astronomers continued to follow the evolution of the
  "GWS zone" centered around 41° planetographic on Saturn. They could
  also detect the hexagonal wave surrounding Saturn's north pole with
  a spot at its edge.

---------------------------------------------------------
Title: TEXES Spectral Mapping of Jupiter and Saturn and the Origins
    of Giant Planet Nitrogen
Authors: Fletcher, L. N.; Greathouse, T. K.; Orton, G. S.; Irwin,
   P. G. J.; Sinclair, J. A.
2013EPSC....8...28F    Altcode:
  We report spectral mapping of the atmospheres of Jupiter and Saturn
  in February 2013 using the Texas Echelon cross Echelle Spectrograph
  (TEXES, [1]) mounted on NASA's Infrared Telescope Facility (IRTF). The
  purpose of these observations was (i) to study jovian meteorology
  via measurements of temperature, wind shear, humidity (i.e., ammonia
  content) and cloud coverage; (ii) to assess the aftermath of Saturn's
  northern 2010-2011 storm, including the continued existence of the
  stratospheric anticyclonic vortex [2]; and (iii) to determine precise
  estimates of the 15N/14N ratio on both planets to constrain the
  origins of nitrogen to the gas giants. Mid-infrared observations of
  this nature complement spacecraft observations from Cassini, Juno and,
  ultimately, JUICE.

---------------------------------------------------------
Title: Cassini Returns to Saturn's Poles: Seasonal Change in the
    Polar Vortices
Authors: Fletcher, L. N.; Orton, G. S.; Irwin, P. G. J.; Sinclair,
   J. A.; Hesman, B. E.; Hurley, J.; Bjoraker, G. L.; Simon-Miller, A. A.
2013EPSC....8...29F    Altcode:
  High inclination orbits during Cassini's solstice mission (2012-2013)
  are providing us with our first observations of Saturn's high
  latitudes since the previous high inclination phase in 2007 (during
  the prime mission). Since that time, the northern spring pole has
  emerged into sunlight and the southern autumn pole has disappeared
  into winter darkness, allowing us to study the seasonal changes
  occurring within the polar vortices in response to these dramatic
  insolation changes. Observations from the Cassini Composite Infrared
  Spectrometer [1] have revealed (i) the continued presence of small,
  cyclonic polar hotspots at both spring and autumn poles [2]; and (ii)
  the emergence of an infrared-bright polar vortex at the north pole,
  consistent with the historical record of Saturn observations from the
  1980s (previous northern spring, [3]).

---------------------------------------------------------
Title: First submillimeter observation of CO in the stratosphere of
    Uranus with Herschel-HIFI
Authors: Cavalié, T.; Moreno, R.; Lellouch, E.; Hartogh, P.; Jarchow,
   C.; Venot, O.; Hersant, F.; Selsis, F.; Orton, G.; Encrenaz, T.;
   Fletcher, L.
2013EPSC....8...72C    Altcode:
  Oxygen-rich deep interiors of the Giant Planets [1] cannot explain
  the discovery of water vapor and carbon dioxide in the stratospheres
  of the Giant Planets by [2] because these species are trapped by
  condensation around their tropopause levels (except CO2 in Jupiter and
  Saturn). Therefore, several sources in the direct or far environment of
  the Giant Planets have been proposed: icy rings and/or satellites [3],
  interplanetary dust particles [4] and large comet impacts [5]. Infrared
  Space Observatory (ISO), Cassini, Odin and Herschel observations
  have proven that the Jovian stratospheric water and carbon dioxide
  originate from the Shoemaker-Levy 9 comet impacts in July 1994 [6, 7],
  while Herschel has recently shown the external flux of water at Saturn
  and Titan is most likely due to the Enceladus geysers and the water
  torus they feed [8, 9]. <P />As for carbon monoxide (CO), the emerging
  picture seems to show more uniformity for its sources. Because CO does
  not condense at the tropopauses of Giant Planets, oxygen-rich interiors
  are a valid source. An internal component has indeed been observed
  in the vertical profile of CO in Jupiter by [10] and in Neptune by
  [11], while an upper limit has been set on its magnitude by [12] for
  Saturn. In addition to interiors, large comets seem to be the dominant
  external source of CO in the Giant Planets, as shown by various studies:
  [10] and [13] for Jupiter, [14] for Saturn and [15] for Neptune. <P
  />Despite its first detection almost a decade ago by [16], the situation
  has remained unclear for Uranus ever since. The (sub)millimeter domain
  with the use of heterodyne spectroscopy has long been considered as
  promising to determine the vertical profile of CO, and thus its origin,
  in Uranus (e.g., [17]). However, attempts made to detect the molecule
  have failed so far in this spectral range, leading only to upper limits
  [18]. In this paper, we present the first submillimeter detection of CO
  in Uranus carried out with the HIFI instrument [19] onboard the Herschel
  Space Observatory [20] in 2011-2012. Using a simple transport model,
  we review the various possible sources of CO (internal and external)
  and constrain their magnitude. For instance, we derive an upper limit
  for the internal source of CO. And with the thermochemical model of
  [21], adapted to the interior of Uranus, we derive an upper limit on
  its deep O/H ratio from it.

---------------------------------------------------------
Title: Constraining the atmosphere of GJ 1214b using an optimal
    estimation technique
Authors: Barstow, J. K.; Aigrain, S.; Irwin, P. G. J.; Fletcher,
   L. N.; Lee, J. -M.
2013MNRAS.434.2616B    Altcode: 2013MNRAS.tmp.1887B; 2013arXiv1306.6567B
  We explore cloudy, extended H<SUB>2</SUB>-He atmosphere scenarios for
  the warm super-Earth GJ 1214b using an optimal estimation retrieval
  technique. This planet, orbiting an M4.5 star only 13 pc from the Earth,
  is of particular interest because it lies between the Earth and Neptune
  in size and may be a member of a new class of planet that is neither
  terrestrial nor gas giant. Its relatively flat transmission spectrum
  has so far made atmospheric characterization difficult. The Non-linear
  optimal Estimator for MultivariateE spectral analySIS (NEMESIS)
  algorithm is used to explore the degenerate model parameter space for
  a cloudy, H<SUB>2</SUB>-He-dominated atmosphere scenario. Optimal
  estimation is a data-led approach that allows solutions beyond the
  range permitted by ab initio equilibrium model atmosphere calculations,
  and as such prevents restriction from prior expectations. We show that
  optimal estimation retrieval is a powerful tool for this kind of study,
  and present an exploration of the degenerate atmospheric scenarios for
  GJ 1214b. Whilst we find a family of solutions that provide a very good
  fit to the data, the quality and coverage of these data are insufficient
  for us to more precisely determine the abundances of cloud and trace
  gases given an H<SUB>2</SUB>-He atmosphere, and we also cannot rule out
  the possibility of a high molecular weight atmosphere. Future ground-
  and space-based observations will provide the opportunity to confirm
  or rule out an extended H<SUB>2</SUB>-He atmosphere, but more precise
  constraints will be limited by intrinsic degeneracies in the retrieval
  problem, such as variations in cloud top pressure and temperature.

---------------------------------------------------------
Title: The 2010-2011 revival of Jupiter's South Equatorial Belt
Authors: Giles, R. S.; Fletcher, L. N.; Irwin, P. G. J.; Orton, G. S.;
   Rogers, J. H.
2013EPSC....8...33G    Altcode:
  In 2009-2010, Jupiter's South Equatorial Belt (SEB) faded to a very pale
  colour before the 2010-2011 revival restored the belt to its ordinary
  dark appearance. Mid-infrared images of the revival were taken using
  VISIR (VLT) across a range of wavelengths from 7 to 25 μm. These were
  used to retrieve changes in temperature and aerosol optical depth as
  the revival proceeded between November 2010 and September 2011.

---------------------------------------------------------
Title: Science goals and concepts of a Saturn probe for the future
    L2/L3 ESA call
Authors: Mousis, O.; Fletcher, L. N.; André, N.; Blanc, M.;
   Coustenis, A.; Gautier, D.; Geppert, W. D.; Guillot, T.; Irwin, P.;
   Lebreton, J. -P.; Marty, B.; Morse, A.; Murray, C.; Petit, J. -M.;
   Sanchez-Lavega, A.; Schmider, F. -X.; Waite, J. H.; Wurz, P.
2013EPSC....8..232M    Altcode:
  A Saturn probe is the next natural step beyond Galileo's in
  situ exploration of Jupiter, and the Cassini spacecraft's orbital
  reconnaissance of Saturn in order to understand the origin of giant
  planets. Here we describe the science goals and concepts of a Saturn
  probe that could be submitted to the future L2/L3 ESA call.

---------------------------------------------------------
Title: From Voyager-IRIS to Cassini-CIRS: Interannual Variability
    in Saturn's Stratosphere
Authors: Sinclair, J. A.; Irwin, P. G. J.; Fletcher, L. N.; Hurley,
   J.; Merlet, C.
2013EPSC....8...35S    Altcode:
  We present an intercomparison of Saturn's atmosphere from Voyager-IRIS
  observations in 1980 with Cassini-CIRS observations in 2009/2010. Over
  a Saturn year (∼29.5 years) has now passed since the Voyager flyby of
  Saturn in 1980/1981. Cassini observations in 2009/2010 and those from
  Voyager therefore capture Saturn in the same season (at approximately
  the vernal equinox, solar longitude, Ls~∼0°). Any differences in
  Saturn's stratospheric properties implied by a comparison of these two
  datasets will therefore highlight interannual variability. We retrieve
  temperature and stratospheric acetylene and ethane concentrations from
  Voyager 1-IRIS (FWHM = 4.3 cm-1) in 1980 and Cassini-CIRS 'FIRMAP'
  (FWHM = 15.5 cm-1) observations in 2009/2010. Preliminary results show
  the equator to be warmer by 7.3 ± 1.6 K at ∼2.1 mbar in 2009 than
  in 1980 implying a differing phase of the SSAO (Saturn's semi-annual
  oscillation). Ethane's meridional distribution at 2.1 mbar appears
  consistent between 1980 and 2009/2010. However, the concentrations
  of acetylene at the same altitude appear enhanced at ∼25°S and
  ∼25°N in 1980 when compared to 2009/2010. A global-circulation
  model shows cells of downwelling at these latitudes [3]: the richer
  concentrations of acetylene at these latitudes in 1980 suggests that
  there was stronger downwelling at this time than in 2009.

---------------------------------------------------------
Title: The flux of impacts in Jupiter: From superbolides to
    large-scale collisions
Authors: Hueso, R.; Pérez-Hoyos, S.; Sánchez-Lavega, A.; . Wesley,
   A.; Hall, G.; Go, C.; Tachikawa, M.; Aoki, K.; Ichimaru, M.; Delcroix,
   M.; Wong, M.; Pond, J. W. T.; Korycansky, D. G.; Palotai, C.; Rebeli,
   N.; Harrington, J.; de Pater, I.; Fletcher, L. N.; Hammel, H.; Orton,
   G. S.; Tabe, I.; Watanabe, J.; Moreno, J. C.
2013EPSC....8..228H    Altcode:
  Observations of Jupiter by a large number of amateurs have resulted
  in the discovery of three fireballs in its atmosphere produced by
  the impacts of small objects. The fireballs were detected on June 3,
  2010, August 20, 2010 and September 10, 2012. The light-curves of these
  atmospheric airbursts provide a measure of the masses and sizes of the
  impacting objects and the statistical significance of the three events
  can be examined from knowledge of the large pool of Jupiter observations
  by the global community of amateur astronomers. These objects are in
  the category of 5-20 m sizes depending on their density and release
  energies comparable to the recent Chelyabinsk airburst. Current biases
  in observations of Jupiter suggest a rate of similar impacts of 18-160
  per year.

---------------------------------------------------------
Title: Clouds on hot Jupiters: implications for transit spectroscopy
Authors: Barstow, J. K.; Aigrain, S.; Irwin, P. G. J.; Fletcher,
   L. N.; Lee, J. -M.
2013EPSC....8..255B    Altcode:
  Since the first detection of a planet orbiting another main sequence
  star, hundreds of extrasolar planets have been confirmed and more than
  2000 candidates have been identified. To date, the best-characterised
  class of planets using this method are the 'hot Jupiters', and evidence
  is now emerging that these hot planets have cloudy atmospheres. Clouds
  and aerosols have a large impact on the spectroscopic signatures
  and radiation balance of the planets in our own solar system; this
  is also true for brown dwarfs, which exist at similar temperatures
  to the hottest of the giant exoplanets. We investigate the effect of
  different types of cloud on the transmission and eclipse spectra of
  hot Jupiters, and will thereby explore ways of breaking degeneracies
  between different model atmosphere scenarios.

---------------------------------------------------------
Title: The Ultraviolet Spectrograph on the JUICE Mission (JUICE-UVS)
Authors: Gladstone, R.; Retherford, K.; Eterno, J.; Persyn, S.; Davis,
   M.; Versteeg, M.; Greathouse, T.; Persson, K.; Dirks, G.; Walther,
   B.; Araujo, M.; Steffl, A.; Schindhelm, R.; Spencer, J.; McGrath,
   M.; Bagenal, F.; Feldman, P.; Fletcher, L.
2013EPSC....8..394G    Altcode:
  The ultraviolet spectrograph instrument for the JUICE mission
  (JUICE-UVS) has been selected to provide a variety of ultraviolet
  science observations during the mission's survey of the Jovian
  system. The goals of our investigation are to explore the atmospheres,
  plasma interactions, and surfaces of the Galilean satellites; to
  determine the dynamics, chemistry, and vertical structure of Jupiter's
  upper atmosphere, from equator to pole, as a template for giant planets
  everywhere; and to investigate the Jupiter-Io connection by quantifying
  energy and mass flow in the Io atmosphere, neutral clouds, and torus. In
  this talk we describe the science objectives for JUICE-UVS, along with
  an overview of its design and expected performance.

---------------------------------------------------------
Title: The transit spectra of the Solar System planets
Authors: Irwin, P. G. J.; Fletcher, L. N.; Barstow, J.; Aigrain, S.;
   Lee, J. -M.
2013EPSC....8...92I    Altcode:
  In recent years, an increasing number of observations have been made
  of the transits of 'Hot Jupiters', such as HD 189733b, from the visible
  through to midinfrared wavelengths, which have been modelled to derive
  the likely atmospheric structure and composition of these planets. As
  measurement techniques improve, the measured transit spectra of
  'Super-Earths' such as GJ 1214b are becoming better constrained,
  allowing model atmospheric states to be fitted for this class of
  planet also. While it is not yet possible to constrain the atmospheric
  states of small planets like the Earth or cold planets like Jupiter,
  it is hoped that this might become practical in the coming decades and
  if so, it is of interest to determine what we might infer from such
  measurements. In this work we have constructed atmospheric models of
  the Solar System planets from 0.2 - 15 μm that are consistent with
  groundbased and satellite observations and from these calculate the
  primary and secondary transit spectra (with respect to the Sun) that
  would be observed by a 'remote observer', many light years away. From
  these spectra we test what current retrieval models might infer about
  their atmospheric states and compare these with the 'ground truths'
  in order to assess: a) the inherent uncertainties in transit spectra
  observations; b) the relative merits of primary versus secondary
  transit spectra; and c) assess the optimal wavelength coverage and
  sensitivities required to retrieve atmospheric states that reasonably
  match the Solar System planet atmospheres.

---------------------------------------------------------
Title: Hot ribbon plasma during the rise phase of a flare
Authors: Fletcher, Lyndsay; Hannah, I.
2013SPD....44...66F    Altcode:
  Strong heating of the chromosphere and transition region during
  flares results in ribbons containing plasma at temperatures ranging
  from a few thousand K to 10 million K. We have used SDO to construct
  emission measure maps in the extended rise phase of the M1.0 event
  SOL2010-08-07T17:55 using the method of Hannah &amp; Kontar (2012),
  allowing a pixel-by-pixel examination of the development of thermal
  plasma in the ribbons, and detailed comparison with the ribbons'
  magnetic environment. Using RHESSI hard X-ray observations we set
  limits on the non-thermal emission from the ribbons, and examine the
  contribution of energy loss by non-thermal electrons to the ribbon
  heating in this phase.

---------------------------------------------------------
Title: Seasonal variations of temperature, acetylene and ethane in
    Saturn's atmosphere from 2005 to 2010, as observed by Cassini-CIRS
Authors: Sinclair, J. A.; Irwin, P. G. J.; Fletcher, L. N.; Moses,
   J. I.; Greathouse, T. K.; Friedson, A. J.; Hesman, B.; Hurley, J.;
   Merlet, C.
2013Icar..225..257S    Altcode:
  Acetylene (C<SUB>2</SUB>H<SUB>2</SUB>) and ethane
  (C<SUB>2</SUB>H<SUB>6</SUB>) are by-products of complex photochemistry
  in the stratosphere of Saturn. Both hydrocarbons are important to
  the thermal balance of Saturn's stratosphere and serve as tracers
  of vertical motion in the lower stratosphere. Earlier studies of
  Saturn's hydrocarbons using Cassini-CIRS observations have provided
  only a snapshot of their behaviour. Following the vernal equinox in
  August 2009, Saturn's northern and southern hemispheres have entered
  spring and autumn, respectively, however the response of Saturn's
  hydrocarbons to this seasonal shift remains to be determined. In this
  paper, we investigate how the thermal structure and concentrations of
  acetylene and ethane have evolved with the changing season on Saturn. We
  retrieve the vertical temperature profiles and acetylene and ethane
  volume mixing ratios from Δν∼=15.5cm<SUP>-1</SUP> Cassini-CIRS
  observations. In comparing 2005 (solar longitude, L<SUB>s</SUB>
  ∼ 308°), 2009 (L<SUB>s</SUB> ∼ 3°) and 2010 (L<SUB>s</SUB>
  ∼ 15°) results, we observe the disappearance of Saturn's warm
  southern polar hood with cooling of up to 17.1 K ± 0.8 K at 1.1 mbar
  at high-southern latitudes. Comparison of the derived temperature
  trend in this region with a radiative climate model (Section 4 of
  Fletcher et al., 2010 and Greathouse et al. (2013, in preparation))
  indicates that this cooling is radiative although dynamical changes
  in this region cannot be ruled out. We observe a 21 ± 12% enrichment
  of acetylene and a 29 ± 11% enrichment of ethane at 25°N from 2005
  to 2009, suggesting downwelling at this latitude. At 15°S, both
  acetylene and ethane exhibit a decrease in concentration of 6 ± 11%
  and 17 ± 9% from 2005 to 2010, respectively, which suggests upwelling
  at this latitude (though a statistically significant change is only
  exhibited by ethane). These implied vertical motions at 15°S and
  25°N are consistent with a recently-developed global circulation
  model of Saturn's tropopause and stratosphere(Friedson and Moses,
  2012), which predicts this pattern of upwelling and downwelling as a
  result of a seasonally-reversing Hadley circulation. Ethane exhibits
  a general enrichment at mid-northern latitudes from 2005 to 2009. As
  the northern hemisphere approaches summer solstice in 2017, this
  feature might indicate an onset of a meridional enrichment of ethane,
  as has been observed in the southern hemisphere during/after southern
  summer solstice.

---------------------------------------------------------
Title: Flare Science with the ATST
Authors: Fletcher, Lyndsay
2013SPD....4440102F    Altcode:
  A flare's radiation appears mostly in the near-UV, optical and
  near infrared, emitted by the dense chromosphere where most of the
  flare energy is ultimately dissipated. Catching flares with a small
  field-of-view imager or a slit-rastering spectrometer is challenging,
  but observations with the ATST will lead to tremendous advances in
  our knowledge of a flare's magnetic environment and its variations,
  the structure and evolution of the flare chromosphere, and the temporal
  and spatial scales of energy transport and dissipation. This talk will
  review in brief our understanding of flares in the ATST's wavelength
  range, and describe some observational goals for flare science with
  the ATST first light instruments.

---------------------------------------------------------
Title: Flare Ribbon Energetics in the Early Phase of an SDO Flare
Authors: Fletcher, L.; Hannah, I. G.; Hudson, H. S.; Innes, D. E.
2013ApJ...771..104F    Altcode: 2014arXiv1401.6538F
  The sites of chromospheric excitation during solar flares are
  marked by extended extreme ultraviolet ribbons and hard X-ray
  (HXR) footpoints. The standard interpretation is that these are
  the result of heating and bremsstrahlung emission from non-thermal
  electrons precipitating from the corona. We examine this picture using
  multi-wavelength observations of the early phase of an M-class flare
  SOL2010-08-07T18:24. We aim to determine the properties of the heated
  plasma in the flare ribbons, and to understand the partition of the
  power input into radiative and conductive losses. Using GOES, SDO/EVE,
  SDO/AIA, and RHESSI, we measure the temperature, emission measure (EM),
  and differential emission measure of the flare ribbons, and deduce
  approximate density values. The non-thermal EM, and the collisional
  thick target energy input to the ribbons are obtained from RHESSI using
  standard methods. We deduce the existence of a substantial amount
  of plasma at 10 MK in the flare ribbons, during the pre-impulsive
  and early-impulsive phase of the flare. The average column EM of
  this hot component is a few times 10<SUP>28</SUP> cm<SUP>-5</SUP>,
  and we can calculate that its predicted conductive losses dominate
  its measured radiative losses. If the power input to the hot ribbon
  plasma is due to collisional energy deposition by an electron beam
  from the corona then a low-energy cutoff of ~5 keV is necessary to
  balance the conductive losses, implying a very large electron energy
  content. Independent of the standard collisional thick-target electron
  beam interpretation, the observed non-thermal X-rays can be provided
  if one electron in 10<SUP>3</SUP>-10<SUP>4</SUP> in the 10 MK (1 keV)
  ribbon plasma has an energy above 10 keV. We speculate that this could
  arise if a non-thermal tail is generated in the ribbon plasma which
  is being heated by other means, for example, by waves or turbulence.

---------------------------------------------------------
Title: Stochastic Simulations of the Pitch-angle Scattering of High
    Energy Electrons
Authors: Dickson, Ewan C.; Kontar, E.; Fletcher, L.
2013SPD....44...56D    Altcode:
  The angular variation of high energy electrons during a solar flare is
  key to understanding the acceleration mechanism. Regularised inversion
  of RHESSI X-ray spectra, using the effect of photospheric albedo, allows
  us to estimate the angular distributions of the emitting electrons. The
  results for all flares studied are consistent with an isotropic
  pitch-angle distribution, and inconsistent with a ratio of downward to
  upward going electron flux greater than 3:1. To attempt to understand
  these results, I have performed stochastic simulations of electron
  pitch-angle scattering by Coulomb collisions, including the effects
  of collisional energy loss, and of magnetic field convergence. This
  allows us to estimate what constraints these observations put on the
  parameters of the electron beam, such as initial directionality, and of
  the characteristics of the loop itself. These simulations suggest that
  Coulomb collisions cannot sufficiently isotropise the distribution to
  be consistent with the observations, even for an initially isotropic
  injected distribution.

---------------------------------------------------------
Title: The properties of flare kernels observed by the Dunn Solar
    Telescope
Authors: Fletcher, Lyndsay; Kowalski, A.; Cauzzi, G.; Hawley, S. L.;
   Hudson, H. S.
2013SPD....44...67F    Altcode:
  We report on a campaign at the Dunn Solar Telescope which resulted in
  successful imaging and spectroscopic observations of a C1.1 solar flare
  on 18th August 2011. This flare exhibited ribbons with complicated
  fine structure at the resolution of the DST/IBIS instrument, and a
  number of bright kernels with sizes comparable to the smallest scales
  sampled by IBIS, around 2-4 pixels (0."3-0."6) FWHM. We focus on these
  bright kernels, describing their spatial characteristics in the core
  and wing of H alpha and Ca II 8542, and in the UV and EUV with SDO. We
  also show preliminary broad-band spectroscopy of the kernels which may
  demonstrate the presence of an optical continuum in this small flare.

---------------------------------------------------------
Title: A new approach to model particle acceleration and energy
    transfer in solar flares
Authors: Rubio Da Costa, Fatima; Zuccarello, F.; Fletcher, L.;
   Labrosse, N.; Kasparova, J.; Prosecký, T.; Carlsson, M.; Petrosian,
   V.; Liu, W.
2013SPD....4440401R    Altcode:
  Motivated by available observations of two different flares in Lyα and
  Hα, we model the conditions of the solar atmosphere using a radiation
  hydrodynamics code (RADYN, Carlsson &amp; Stein, 1992) and analyze the
  energy transport carried by a beam of non-thermal electrons injected
  at the top of a 1D coronal loop. The numerical Lyα and Hα intensities
  match with the observations. The electron energy distribution is assumed
  to follow a power law of the form (E/E<SUP>c</SUP> )<SUB>-δ</SUB> for
  energies greater than a cutoff value of E<SUP>c</SUP>. Abbett &amp;
  Hawley (1999) and Allred et al. (2005) assumed that the non-thermal
  electrons flux injected at the top of a flaring loop, the cut-off energy
  and the power law index are constant over time. An improvement was
  achieved by Allred &amp; Hawley (2006), who modified the RADYN code
  in such a way that the input parameters were time dependent. Their
  inputs were based on observations of a flare obtained with RHESSI. By
  combining RADYN with the “flare” code from Stanford University
  which models the acceleration and transport of particles and radiation
  of solar flares in non-LTE regime, we can calculate the non-thermal
  electrons flux, the cut-off energy and the power law index at every
  simulated time step. The atmospheric parameters calculated by RADYN
  could in turn be used as updated inputs for "flare", providing several
  advantages over the results from Liu et al. (2009), who combined the
  particle acceleration code with a 1-D hydrodynamic code, improving
  the atmospheric conditions.

---------------------------------------------------------
Title: Impulsive Thermal X-Ray Emission from a Low-lying Coronal Loop
Authors: Liu, Siming; Li, Youping; Fletcher, Lyndsay
2013ApJ...769..135L    Altcode: 2013arXiv1304.5584L
  Understanding the relationship among different emission components plays
  an essential role in the study of particle acceleration and energy
  conversion in solar flares. In flares where gradual and impulsive
  emission components can be readily identified, the impulsive emission
  has been attributed to non-thermal particles. We carry out detailed
  analysis of Hα and X-ray observations of a GOES class B microflare
  loop on the solar disk. The impulsive hard X-ray emission, however,
  is found to be consistent with a hot, quasi-thermal origin, and
  there is little evidence of emission from chromospheric footpoints,
  which challenges conventional models of flares and reveals a class of
  microflares associated with dense loops. Hα observations indicate that
  the loop lies very low in the solar corona or even in the chromosphere
  and both emission and absorption materials evolve during the flare. The
  enhanced Hα emission may very well originate from the photosphere
  when the low-lying flare loop heats up the underlying chromosphere
  and reduces the corresponding Hα opacity. These observations may be
  compared with detailed modeling of flare loops with the internal kink
  instability, where the mode remains confined in space without apparent
  change in the global field shape, to uncover the underlying physical
  processes and to probe the structure of solar atmosphere.

---------------------------------------------------------
Title: JUpiter ICy moons Explorer (JUICE): An ESA mission to orbit
    Ganymede and to characterise the Jupiter system
Authors: Grasset, O.; Dougherty, M. K.; Coustenis, A.; Bunce, E. J.;
   Erd, C.; Titov, D.; Blanc, M.; Coates, A.; Drossart, P.; Fletcher,
   L. N.; Hussmann, H.; Jaumann, R.; Krupp, N.; Lebreton, J. -P.;
   Prieto-Ballesteros, O.; Tortora, P.; Tosi, F.; Van Hoolst, T.
2013P&SS...78....1G    Altcode:
  Past exploration of Jupiter's diverse satellite system has forever
  changed our understanding of the unique environments to be found
  around gas giants, both in our solar system and beyond. The detailed
  investigation of three of Jupiter's Galilean satellites (Ganymede,
  Europa, and Callisto), which are believed to harbour subsurface water
  oceans, is central to elucidating the conditions for habitability of
  icy worlds in planetary systems in general. The study of the Jupiter
  system and the possible existence of habitable environments offer
  the best opportunity for understanding the origins and formation of
  the gas giants and their satellite systems. The JUpiter ICy moons
  Explorer (JUICE) mission, selected by ESA in May 2012 to be the
  first large mission within the Cosmic Vision Program 2015-2025, will
  perform detailed investigations of Jupiter and its system in all their
  inter-relations and complexity with particular emphasis on Ganymede
  as a planetary body and potential habitat. The investigations of the
  neighbouring moons, Europa and Callisto, will complete a comparative
  picture of the Galilean moons and their potential habitability. Here we
  describe the scientific motivation for this exciting new European-led
  exploration of the Jupiter system in the context of our current
  knowledge and future aspirations for exploration, and the paradigm it
  will bring in the study of giant (exo) planets in general.

---------------------------------------------------------
Title: On the potential of the EChO mission to characterize gas
    giant atmospheres
Authors: Barstow, J. K.; Aigrain, S.; Irwin, P. G. J.; Bowles, N.;
   Fletcher, L. N.; Lee, J. -M.
2013MNRAS.430.1188B    Altcode: 2013MNRAS.tmp..637B; 2013MNRAS.tmp..679B
  Space telescopes such as Exoplanet Characterisation Observatory (EChO)
  and James Webb Space Telescope (JWST) will be important for the future
  study of extrasolar planet atmospheres. Both of these missions are
  capable of performing high sensitivity spectroscopic measurements
  at moderate resolutions in the visible and infrared, which will
  allow the characterization of atmospheric properties using primary
  and secondary transit spectroscopy. We use the Non-linear optimal
  Estimator for MultivariateE spectral analysis (NEMESIS) radiative
  transfer and retrieval tool, as developed by Irwin et al. and Lee
  et al., to explore the potential of the proposed EChO mission to
  solve the retrieval problem for a range of H<SUB>2</SUB>-He planets
  orbiting different stars. We find that EChO should be capable of
  retrieving temperature structure to ∼200 K precision and detecting
  H<SUB>2</SUB>O, CO<SUB>2</SUB> and CH<SUB>4</SUB> from a single
  eclipse measurement for a hot Jupiter orbiting a Sun-like star and a
  hot Neptune orbiting an M star, also providing upper limits on CO and
  NH<SUB>3</SUB>. We provide a table of retrieval precisions for these
  quantities in each test case. We expect around 30 Jupiter-sized planets
  to be observable by EChO; hot Neptunes orbiting M dwarfs are rarer,
  but we anticipate observations of at least one similar planet.

---------------------------------------------------------
Title: The Emission Measure Distribution of Impulsive Phase Flare
    Footpoints
Authors: Graham, D. R.; Hannah, I. G.; Fletcher, L.; Milligan, R. O.
2013ApJ...767...83G    Altcode: 2013arXiv1302.2514G
  The temperature distribution of the emitting plasma is a crucial
  constraint when studying the heating of solar flare footpoints. However,
  determining this for impulsive phase footpoints has been difficult
  in the past due to insufficient spatial resolution to resolve the
  footpoints from the loop structures, and a lack of spectral and temporal
  coverage. We use the capabilities of Hinode/Extreme Ultraviolet Imaging
  Spectrometer to obtain the first emission measure distributions (EMDs)
  from impulsive phase footpoints in six flares. Observations with good
  spectral coverage were analyzed using a regularized inversion method to
  recover the EMDs. We find that the EMDs all share a peak temperature of
  around 8 MK, with lines formed around this temperature having emission
  measures (EMs) peaking between 10<SUP>28</SUP> and 10<SUP>29</SUP>
  cm<SUP>-5</SUP>, indicating a substantial presence of plasma at very
  high temperatures within the footpoints. An EMD gradient of EM(T) ~
  T is found in all events. Previous theoretical work on EM gradients
  shows this to be consistent with a scenario in which the deposited flare
  energy directly heats only the top layer of the flare chromosphere,
  while deeper layers are heated by conduction.

---------------------------------------------------------
Title: Propagation of Alfvénic Waves from Corona to Chromosphere
    and Consequences for Solar Flares
Authors: Russell, A. J. B.; Fletcher, L.
2013ApJ...765...81R    Altcode: 2013arXiv1302.2458R
  How do magnetohydrodynamic waves travel from the fully ionized corona,
  into and through the underlying partially ionized chromosphere, and
  what are the consequences for solar flares? To address these questions,
  we have developed a two-fluid model (of plasma and neutrals) and used
  it to perform one-dimensional simulations of Alfvén waves in a solar
  atmosphere with realistic density and temperature structure. Studies of
  a range of solar features (faculae, plage, penumbra, and umbra) show
  that energy transmission from corona to chromosphere can exceed 20%
  of incident energy for wave periods of 1 s or less. Damping of waves
  in the chromosphere depends strongly on wave frequency: waves with
  periods 10 s or longer pass through the chromosphere with relatively
  little damping, however, for periods of 1 s or less, a substantial
  fraction (37%-100%) of wave energy entering the chromosphere is
  damped by ion-neutral friction in the mid- and upper chromosphere,
  with electron resistivity playing some role in the lower chromosphere
  and in umbras. We therefore conclude that Alfvénic waves with periods
  of a few seconds or less are capable of heating the chromosphere during
  solar flares, and speculate that they could also contribute to electron
  acceleration or exciting sunquakes.

---------------------------------------------------------
Title: A Gemini ground-based transmission spectrum of WASP-29b:
    a featureless spectrum from 515 to 720 nm
Authors: Gibson, N. P.; Aigrain, S.; Barstow, J. K.; Evans, T. M.;
   Fletcher, L. N.; Irwin, P. G. J.
2013MNRAS.428.3680G    Altcode: 2012arXiv1210.7798G
  We report Gemini-South Gemini Multi-Object Spectrograph observations of
  the exoplanet system WASP-29 during primary transit as a test case for
  differential spectrophotometry. We use the multi-object spectrograph
  to observe the target star and a comparison star simultaneously to
  produce multiple light curves at varying wavelengths. The `white'
  light curve and 15 `spectral' light curves are analysed to refine the
  system parameters and produce a transmission spectrum from ∼515 to
  720 nm. All light curves exhibit time-correlated noise, which we model
  using a variety of techniques. These include a simple noise rescaling,
  a Gaussian process model and a wavelet-based method. These methods all
  produce consistent results, although with different uncertainties. The
  precision of the transmission spectrum is improved by subtracting a
  common signal from all the spectral light curves, reaching a typical
  precision of ∼1 × 10<SUP>-4</SUP> in transit depth. The transmission
  spectrum is free of spectral features, and given the non-detection
  of a pressure broadened Na feature, we can rule out the presence
  of a Na-rich atmosphere free of clouds or hazes, although we cannot
  rule out a narrow Na core. This indicates that Na is not present in
  the atmosphere, and/or that clouds/hazes play a significant role in
  the atmosphere and mask the broad wings of the Na feature, although
  the former is a more likely explanation given WASP-29b's equilibrium
  temperature of ∼970 K, at which Na can form various compounds. We
  also briefly discuss the use of Gaussian process and wavelet methods
  to account for time-correlated noise in transit light curves.

---------------------------------------------------------
Title: Particle acceleration and dynamical heating in Cycle 24 flares
Authors: Hannah, I. G.; Fletcher, L.; Kontar, E. P.
2012AGUFMSH51C..07H    Altcode:
  The current wealth of solar observations presents a unique opportunity
  to study energy release in solar flares, particularly particle
  acceleration and plasma heating. The spatial and temporal resolution
  of SDO/AIA EUV data give an unprecedented view of dynamical heating
  in solar flares yet to fully exploit this resource the underlying
  thermal properties of the emitting plasma needs to be recovered. This
  is difficult as it is an ill-posed inverse problem and there is
  copious data. Our recently implemented regularized inversion method
  (Hannah &amp; Kontar A&amp;A 2012a,b) can quickly and robustly find the
  Differential Emission Measure (DEM) solution (and its uncertainties),
  with the resulting EM maps allowing the temperature and density
  evolution to be studied both spatially and temporally. Combing this with
  the hard X-ray imaging and spectroscopy of RHESSI, we present a study of
  the non-thermal energy input and thermal response in some flares of the
  rising phase of cycle 24. We also look at the relationship between the
  energetics of flares and the underlying magnetic field configurations.

---------------------------------------------------------
Title: Latitudinal variation of upper tropospheric NH<SUB>3</SUB>
    on Saturn derived from Cassini/CIRS far-infrared measurements
Authors: Hurley, J.; Fletcher, L. N.; Irwin, P. G. J.; Calcutt, S. B.;
   Sinclair, J. A.; Merlet, C.
2012P&SS...73..347H    Altcode:
  Ammonia (NH<SUB>3</SUB>) has been detected both on Saturn and Jupiter,
  and although its concentration and distribution has been well-studied
  on Jupiter, it has proven more difficult to do so on Saturn due
  to higher sensitivity requirements resulting from Saturn's lower
  atmospheric temperatures and the dominance of Saturn's phosphine
  which masks the ammonia signal. Using far-infrared measurements of
  Saturn taken by Cassini/CIRS between February 2005 and December 2010,
  the latitudinal variations of upper tropospheric ammonia on Saturn
  are studied. Sensitivity to NH<SUB>3</SUB> in the far-infrared is
  explored to provide estimates of temperature, para-H<SUB>2</SUB>
  and PH<SUB>3</SUB>, from 2.5 cm<SUP>-1</SUP> spectral resolution
  measurements alone, 0.5 cm<SUP>-1</SUP> spectral-resolution
  measurements alone, and 0.5 cm<SUP>-1</SUP> measurements degraded
  to 2.5 cm<SUP>-1</SUP> spectral resolution. The estimates of
  NH<SUB>3</SUB> from these three different datasets largely agree,
  although there are notable differences using the high emission angle
  0.5 cm<SUP>-1</SUP> data, which are asserted to result from a reduction
  in sensitivity at higher emission angles. For low emission angles,
  the 0.5 cm<SUP>-1</SUP>-retrieved values of NH<SUB>3</SUB> can be used
  to reproduce the 2.5 cm<SUP>-1</SUP> spectra with similar efficacy as
  those derived directly from the 2.5 cm<SUP>-1</SUP> resolution data
  itself, and vice versa. Using low emission angle data, NH<SUB>3</SUB>
  is observed to have broad peak abundances at ±25° latitude, attributed
  to result from condensation and/or photolytic processes. Lack of data
  coverage at equatorial latitudes precludes analysis of NH<SUB>3</SUB>
  abundance at less than about 10° latitude. Noise levels are not
  sufficient to distinguish fine zonal features, although it seems that
  NH<SUB>3</SUB> cannot trace the zonal belt/zone structure in the upper
  troposphere of Saturn.

---------------------------------------------------------
Title: Photochemistry in Saturn's Ring Shadowed Atmosphere: Production
    Rates of Key Atmospheric Molecules and Preliminary Analysis of
    Observations
Authors: Edgington, S. G.; Atreya, S. K.; Wilson, E. H.; West, R. A.;
   Baines, K. H.; Bjoraker, G. L.; Fletcher, L. N.; Momary, T.
2012AGUFM.P13B1946E    Altcode:
  Cassini has been orbiting Saturn for over eight years. During this
  epoch, the ring shadow has moved from shading a large portion of
  the northern hemisphere (the ring plane was inclined by ~24 degrees
  relative to the Sun-Saturn vector) to shading mid-latitudes south
  of the equator and continues southward. At its maximum extent,
  the projection of the ring plane shadow onto Saturn can reach as
  far as 48N (~58N at the terminator). The net result, is that the
  intensity of both ultraviolet and visible sunlight penetrating onto
  any particular northern/southern latitude will vary depending on
  Saturn's tilt relative to the Sun and the optical thickness of each
  ring system. Our previous work has examined the variation of the solar
  flux as a function of solar inclination, i.e. season on Saturn. Here we
  report on the impact of the oscillating ring shadow on the photolysis
  and production rates of key hydrocarbons in Saturn's stratosphere and
  upper troposphere, including ethane, acetylene, propane, benzene. We
  investigate the impact on production and loss rates of the long-lived,
  photochemical hydrocarbons leading to haze formation at several
  latitudes over one Saturn year. Similarly, we assess the impact on
  the abundance of phosphine, a disequilibrium species whose presence
  in the upper troposphere is a tracer of convection processes in the
  deep atmosphere. Along with the above, we present preliminary analysis
  of Cassini's UVIS and VIMS datasets that provide an estimate of the
  evolving haze content of the northern hemisphere. We will also compare
  our model results to abundances determined from previously released
  CIRS observations. The research described in this paper was carried out
  at the Jet Propulsion Laboratory, California Institute of Technology,
  under a contract with the National Aeronautics and Space Administration.

---------------------------------------------------------
Title: Properties of Slowly Moving Thermal Waves in Saturn from
    Cassini CIRS Observations from 2004 to 2009
Authors: Orton, G. S.; Fletcher, L. N.; Flasar, F. M.; Achterberg,
   R. K.; Brown, S. K.
2012AGUFM.P13B1928O    Altcode:
  Hemispherical maps of Saturn's atmosphere made by the Cassini
  Composite Infrared Spectrometer (CIRS) were surveyed for the presence
  and properties of zonal thermal waves and their variability in
  time. The most inclusive surveys in latitude, FIRMAPs (15 cm-1 spectral
  resolution), covered the planet from the equator to either the north or
  south pole, sweeping through the latitude range while the planet rotated
  beneath over its ~10-hour rotation. Four spectral ranges were sampled:
  two in a region dominated by upper-tropospheric emission (80-200 mbar)
  from collision-induced H2 opacity and two in regions dominated by
  stratospheric emission (0.5-3 mbar) from ethane (12.3 μm) and methane
  (7.7 μm), respectively. We examined maps that were taken between 2004
  and Saturn's spring equinox in 2009. During this time, the strongest
  waves were found between planetographic latitudes of 30° and 45° S;
  in the northern hemisphere, they were found between the equator and
  30°N. Some low-wavenumber components cover all 360° in longitude,
  similar to the slowly moving thermal waves in Jupiter's atmosphere,
  but the strongest waves were found in "trains" that covered only one
  hemisphere or less. In 2005, tropospheric waves had a mean peak-to-peak
  variance that was the equivalent of temperature variability of about 1
  K. Between 2005 and 2007, they had subsided to about 0.5 K. During and
  after 2008 they soared to over 3 K. During this entire period, similar
  waves in the northern hemisphere were never larger than 0.8 K. In the
  stratosphere, waves followed a similar time sequence, with southern
  hemisphere waves in 2005 reaching as much as 3.5 K in brightness
  temperature, subsequently decreasing, then growing in 2008-2009 to
  over 5 K. Stratospheric waves in the northern hemisphere were nearly
  constant around 2 K, but with an instance of 6 K at one epoch in
  2008. The phase of the waves moved about 0.5° of longitude per day
  retrograde with respect to System III. The phase of tropospheric and
  stratospheric waves appeared to be highly correlated with one another,
  with little offset in longitude.

---------------------------------------------------------
Title: Elusive Ethylene Detected in Saturn's Northern Storm Region
Authors: Hesman, B. E.; Bjoraker, G. L.; Sada, P. V.; Achterberg,
   R. K.; Jennings, D. E.; Romani, P. N.; Lunsford, A. W.; Fletcher,
   L. N.; Boyle, R. J.; Simon-Miller, A. A.; Nixon, C. A.; Irwin, P. G. J.
2012ApJ...760...24H    Altcode:
  The massive eruption at 40°N (planetographic latitude) on Saturn
  in 2010 December has produced significant and lasting effects in
  the northern hemisphere on temperature and species abundances. The
  northern storm region was observed on many occasions in 2011 by
  Cassini's Composite Infrared Spectrometer (CIRS). In 2011 May,
  temperatures in the stratosphere greater than 200 K were derived from
  CIRS spectra in the regions referred to as "beacons" (warm regions in
  the stratosphere). Ethylene has been detected in the beacon region in
  Saturn's northern storm region using CIRS. Ground-based observations
  using the high-resolution spectrometer Celeste on the McMath-Pierce
  Telescope on 2011 May 15 were used to confirm the detection and improve
  the altitude resolution in the retrieved profile. The derived ethylene
  profile from the CIRS data gives a C<SUB>2</SUB>H<SUB>4</SUB> mole
  fraction of 5.9 ± 4.5 × 10<SUP>-7</SUP> at 0.5 mbar, and from Celeste
  data it gives 2.7 ± 0.45 × 10<SUP>-6</SUP> at 0.1 mbar. This is two
  orders of magnitude higher than the amount measured in the ultraviolet
  at other latitudes prior to the storm. It is also much higher than
  predicted by photochemical models, indicating that perhaps another
  production mechanism is required or a loss mechanism is being inhibited.

---------------------------------------------------------
Title: Unusual Stokes V profiles during flaring activity of a
    delta sunspot
Authors: Fischer, C. E.; Keller, C. U.; Snik, F.; Fletcher, L.;
   Socas-Navarro, H.
2012A&A...547A..34F    Altcode: 2012arXiv1209.0983F
  <BR /> Aims: We analyze a set of full Stokes profile observations of
  the flaring active region NOAA 10808. The region was recorded with
  the Vector-Spectromagnetograph of the Synoptic Optical Long-term
  Investigations of the Sun facility. The active region produced
  several successive X-class flares between 19:00 UT and 24:00 UT on
  September 13, 2005 and we aim to quantify transient and permanent
  changes in the magnetic field and velocity field during one of the
  flares, which has been fully captured. <BR /> Methods: The Stokes
  profiles were inverted using the height-dependent inversion code
  LILIA to analyze magnetic field vector changes at the flaring site. We
  report multilobed asymmetric Stokes V profiles found in the δ-sunspot
  umbra. We fit the asymmetric Stokes V profiles assuming an atmosphere
  consisting of two components (SIR inversions) to interpret the profile
  shape. The results are put in context with Michelson Doppler Imager
  (MDI) magnetograms and reconstructed X-ray images from the Reuven
  Ramaty High Energy Solar Spectroscopic Imager. <BR /> Results: We
  obtain the magnetic field vector and find signs of restructuring
  of the photospheric magnetic field during the flare close to the
  polarity inversion line at the flaring site. At two locations in the
  umbra we encounter strong fields (~3 kG), as inferred from the Stokes
  I profiles, which, however, exhibit a low polarization signal. During
  the flare we observe in addition asymmetric Stokes V profiles at one
  of these sites. The asymmetric Stokes V profiles appear co-spatial
  and co-temporal with a strong apparent polarity reversal observed
  in MDI-magnetograms and a chromospheric hard X-ray source. The
  two-component atmosphere fits of the asymmetric Stokes profiles
  result in line-of-sight velocity differences in the range of ~12 km
  s<SUP>-1</SUP> to 14 km s<SUP>-1</SUP> between the two components in
  the photosphere. Another possibility is that local atmospheric heating
  is causing the observed asymmetric Stokes V profile shape. In either
  case our analysis shows that a very localized patch of ~5″ in the
  photospheric umbra, co-spatial with a flare footpoint, exhibits a
  subresolution fine structure.

---------------------------------------------------------
Title: Ethylene Emission in the Aftermath of Saturn’s 2010
    Northern Storm
Authors: Hesman, Brigette E.; Bjoraker, G. L.; Sada, P. V.; Achterberg,
   R. K.; Jennings, D. E.; Lunsford, A. W.; Romani, P. N.; Fletcher,
   L. N.; Boyle, R. J.; Kerr, T.; Sinclair, J. A.; Nixon, C. A.; Davis,
   G. R.; Irwin, P. G. J.
2012DPS....4440306H    Altcode:
  The massive eruption at 40N (planetographic latitude) in December
  2010 has produced significant and long-lived changes in temperature
  and species abundances in Saturn’s northern hemisphere (Fletcher
  et al. 2011). The northern storm region has been observed on many
  occasions between January 2011 and June of 2012 by Cassini’s Composite
  Infrared Spectrometer (CIRS). In this time period, temperatures in
  regions referred to as “beacons” (warm regions in the stratosphere
  at certain longitudes in the storm latitude) became significantly
  warmer than pre-storm values of 140K. A significant finding in the
  beacon region has been ethylene emission; a molecule that has been
  challenging to detect on Saturn but is an important species in
  Saturn’s photochemistry. The derived ethylene profile from the
  CIRS data gives a C<SUB>2</SUB>H<SUB>4</SUB> mole fraction of 5.9
  ± 4.5x10<SUP>-7</SUP> at 0.5 mbar. Ground-based observations were
  performed using the high-resolution spectrometer Celeste to study
  ethylene’s spectral signatures at higher spectral resolution than
  available with CIRS. Analysis of the May 2011 Celeste data finds a
  C<SUB>2</SUB>H<SUB>4</SUB> mole fraction of 2.7 ± 0.45x10<SUP>-6</SUP>
  at 0.1 mbar. The ethylene abundances derived from CIRS and Celeste
  observations are two orders of magnitude higher than predicted by
  photochemical models, indicating that perhaps another production
  mechanism is required or a loss mechanism is being inhibited. To
  investigate the source of ethylene in the beacon region the temporal
  evolution of this molecule will be presented based on data collected by
  CIRS, between January 2011 and June 2012, together with ground-based
  Celeste observations from the McMath-Pierce Telescope (May 2011), the
  United Kingdom Infrared Telescope (July 2011), and the NASA Infrared
  Telescope Facility (April 2012). References: Fletcher, L. N. et al.,
  2011. Thermal Structure and Dynamics of Saturn’s Northern Springtime
  Disturbance. Science 332, 1413-1417.

---------------------------------------------------------
Title: OSS (Outer Solar System): a fundamental and planetary physics
    mission to Neptune, Triton and the Kuiper Belt
Authors: Christophe, B.; Spilker, L. J.; Anderson, J. D.; André,
   N.; Asmar, S. W.; Aurnou, J.; Banfield, D.; Barucci, A.; Bertolami,
   O.; Bingham, R.; Brown, P.; Cecconi, B.; Courty, J. -M.; Dittus, H.;
   Fletcher, L. N.; Foulon, B.; Francisco, F.; Gil, P. J. S.; Glassmeier,
   K. H.; Grundy, W.; Hansen, C.; Helbert, J.; Helled, R.; Hussmann, H.;
   Lamine, B.; Lämmerzahl, C.; Lamy, L.; Lehoucq, R.; Lenoir, B.; Levy,
   A.; Orton, G.; Páramos, J.; Poncy, J.; Postberg, F.; Progrebenko,
   S. V.; Reh, K. R.; Reynaud, S.; Robert, C.; Samain, E.; Saur, J.;
   Sayanagi, K. M.; Schmitz, N.; Selig, H.; Sohl, F.; Spilker, T. R.;
   Srama, R.; Stephan, K.; Touboul, P.; Wolf, P.
2012ExA....34..203C    Altcode: 2011arXiv1106.0132C; 2012ExA...tmp...32C
  The present OSS (Outer Solar System) mission continues a long and
  bright tradition by associating the communities of fundamental physics
  and planetary sciences in a single mission with ambitious goals in both
  domains. OSS is an M-class mission to explore the Neptune system almost
  half a century after the flyby of the Voyager 2 spacecraft. Several
  discoveries were made by Voyager 2, including the Great Dark Spot
  (which has now disappeared) and Triton's geysers. Voyager 2 revealed
  the dynamics of Neptune's atmosphere and found four rings and evidence
  of ring arcs above Neptune. Benefiting from a greatly improved
  instrumentation, a mission as OSS would result in a striking advance
  in the study of the farthest planet of the solar system. Furthermore,
  OSS would provide a unique opportunity to visit a selected Kuiper Belt
  object subsequent to the passage of the Neptunian system. OSS would
  help consolidate the hypothesis of the origin of Triton as a Kuiper
  Belt object captured by Neptune, and to improve our knowledge on the
  formation of the solar system. The OSS probe would carry instruments
  allowing precise tracking of the spacecraft during the cruise. It
  would facilitate the best possible tests of the laws of gravity in
  deep space. These objectives are important for fundamental physics,
  as they test General Relativity, our current theoretical description
  of gravitation, but also for cosmology, astrophysics and planetary
  science, as General Relativity is used as a tool in all these
  domains. In particular, the models of solar system formation uses
  General Relativity to describe the crucial role of gravity. OSS is
  proposed as an international cooperation between ESA and NASA, giving
  the capability for ESA to launch an M-class mission towards the farthest
  planet of the solar system, and to a Kuiper Belt object. The proposed
  mission profile would allow to deliver a 500 kg class spacecraft. The
  design of the probe is mainly constrained by the deep space gravity test
  in order to minimize the perturbation of the accelerometer measurement.

---------------------------------------------------------
Title: EChO. Exoplanet characterisation observatory
Authors: Tinetti, G.; Beaulieu, J. P.; Henning, T.; Meyer, M.;
   Micela, G.; Ribas, I.; Stam, D.; Swain, M.; Krause, O.; Ollivier,
   M.; Pace, E.; Swinyard, B.; Aylward, A.; van Boekel, R.; Coradini,
   A.; Encrenaz, T.; Snellen, I.; Zapatero-Osorio, M. R.; Bouwman, J.;
   Cho, J. Y. -K.; Coudé de Foresto, V.; Guillot, T.; Lopez-Morales, M.;
   Mueller-Wodarg, I.; Palle, E.; Selsis, F.; Sozzetti, A.; Ade, P. A. R.;
   Achilleos, N.; Adriani, A.; Agnor, C. B.; Afonso, C.; Allende Prieto,
   C.; Bakos, G.; Barber, R. J.; Barlow, M.; Batista, V.; Bernath, P.;
   Bézard, B.; Bordé, P.; Brown, L. R.; Cassan, A.; Cavarroc, C.;
   Ciaravella, A.; Cockell, C.; Coustenis, A.; Danielski, C.; Decin,
   L.; De Kok, R.; Demangeon, O.; Deroo, P.; Doel, P.; Drossart, P.;
   Fletcher, L. N.; Focardi, M.; Forget, F.; Fossey, S.; Fouqué, P.;
   Frith, J.; Galand, M.; Gaulme, P.; González Hernández, J. I.;
   Grasset, O.; Grassi, D.; Grenfell, J. L.; Griffin, M. J.; Griffith,
   C. A.; Grözinger, U.; Guedel, M.; Guio, P.; Hainaut, O.; Hargreaves,
   R.; Hauschildt, P. H.; Heng, K.; Heyrovsky, D.; Hueso, R.; Irwin, P.;
   Kaltenegger, L.; Kervella, P.; Kipping, D.; Koskinen, T. T.; Kovács,
   G.; La Barbera, A.; Lammer, H.; Lellouch, E.; Leto, G.; Lopez Morales,
   M.; Lopez Valverde, M. A.; Lopez-Puertas, M.; Lovis, C.; Maggio, A.;
   Maillard, J. P.; Maldonado Prado, J.; Marquette, J. B.; Martin-Torres,
   F. J.; Maxted, P.; Miller, S.; Molinari, S.; Montes, D.; Moro-Martin,
   A.; Moses, J. I.; Mousis, O.; Nguyen Tuong, N.; Nelson, R.; Orton,
   G. S.; Pantin, E.; Pascale, E.; Pezzuto, S.; Pinfield, D.; Poretti,
   E.; Prinja, R.; Prisinzano, L.; Rees, J. M.; Reiners, A.; Samuel,
   B.; Sánchez-Lavega, A.; Forcada, J. Sanz; Sasselov, D.; Savini, G.;
   Sicardy, B.; Smith, A.; Stixrude, L.; Strazzulla, G.; Tennyson, J.;
   Tessenyi, M.; Vasisht, G.; Vinatier, S.; Viti, S.; Waldmann, I.;
   White, G. J.; Widemann, T.; Wordsworth, R.; Yelle, R.; Yung, Y.;
   Yurchenko, S. N.
2012ExA....34..311T    Altcode: 2012ExA...tmp...35T; 2011arXiv1112.2728T
  A dedicated mission to investigate exoplanetary atmospheres represents
  a major milestone in our quest to understand our place in the
  universe by placing our Solar System in context and by addressing the
  suitability of planets for the presence of life. EChO—the Exoplanet
  Characterisation Observatory—is a mission concept specifically geared
  for this purpose. EChO will provide simultaneous, multi-wavelength
  spectroscopic observations on a stable platform that will allow very
  long exposures. The use of passive cooling, few moving parts and well
  established technology gives a low-risk and potentially long-lived
  mission. EChO will build on observations by Hubble, Spitzer and
  ground-based telescopes, which discovered the first molecules and
  atoms in exoplanetary atmospheres. However, EChO's configuration
  and specifications are designed to study a number of systems in a
  consistent manner that will eliminate the ambiguities affecting prior
  observations. EChO will simultaneously observe a broad enough spectral
  region—from the visible to the mid-infrared—to constrain from
  one single spectrum the temperature structure of the atmosphere, the
  abundances of the major carbon and oxygen bearing species, the expected
  photochemically-produced species and magnetospheric signatures. The
  spectral range and resolution are tailored to separate bands belonging
  to up to 30 molecules and retrieve the composition and temperature
  structure of planetary atmospheres. The target list for EChO includes
  planets ranging from Jupiter-sized with equilibrium temperatures T
  <SUB>eq</SUB> up to 2,000 K, to those of a few Earth masses, with
  T <SUB>eq</SUB> u223c 300 K. The list will include planets with no
  Solar System analog, such as the recently discovered planets GJ1214b,
  whose density lies between that of terrestrial and gaseous planets,
  or the rocky-iron planet 55 Cnc e, with day-side temperature close to
  3,000 K. As the number of detected exoplanets is growing rapidly each
  year, and the mass and radius of those detected steadily decreases, the
  target list will be constantly adjusted to include the most interesting
  systems. We have baselined a dispersive spectrograph design covering
  continuously the 0.4-16 μm spectral range in 6 channels (1 in the
  visible, 5 in the InfraRed), which allows the spectral resolution to
  be adapted from several tens to several hundreds, depending on the
  target brightness. The instrument will be mounted behind a 1.5 m class
  telescope, passively cooled to 50 K, with the instrument structure and
  optics passively cooled to u223c45 K. EChO will be placed in a grand
  halo orbit around L2. This orbit, in combination with an optimised
  thermal shield design, provides a highly stable thermal environment and
  a high degree of visibility of the sky to observe repeatedly several
  tens of targets over the year. Both the baseline and alternative
  designs have been evaluated and no critical items with Technology
  Readiness Level (TRL) less than 4-5 have been identified. We have also
  undertaken a first-order cost and development plan analysis and find
  that EChO is easily compatible with the ESA M-class mission framework.

---------------------------------------------------------
Title: JUpiter ICy Moons Explorer (JUICE): The ESA L1 Mission to
    the Jupiter System
Authors: Dougherty, M. K.; Grasset, O.; Erd, C.; Titov, D.; Bunce,
   E.; Coustenis, A.; Blanc, M.; Coates, A.; Drossart, P.; Fletcher,
   L.; Hussmann, H.; Jaumann, R.; Krupp, N.; Prieto-Ballesteros, O.;
   Tortora, P.; Tosi, F.; Van Hoolst, T.
2012LPICo1683.1039D    Altcode:
  The Jupiter Icy Moons Explorer (JUICE) mission has recently been
  selected by ESA as the first large mission within the Cosmic Visions
  2015-2025 plan. We will introduce the mission that is being developed
  to thoroughly explore the Jupiter system with focus on the largest
  satellite, Ganymede.

---------------------------------------------------------
Title: Clouds and Hazes in Saturn's Troposphere and Stratosphere
Authors: Merlet, Cecile; Irwin, P.; Fletcher, L.
2012DPS....4441215M    Altcode:
  We present new results from the analysis of Saturn's near-infrared
  spectra measured with the Visual and Infrared Mapping Spectrometer
  (VIMS) instrument on the Cassini orbiter. VIMS near-infrared data
  are particularly relevant for the study of clouds and hazes in the
  troposphere and stratosphere of Saturn. Thermal emission in the 4.5-5.1
  wavelength range is absorbed and scattered mainly by tropospheric clouds
  and radiatively active gases. The vertical structure as well as the
  optical and physical properties of tropospheric aerosols are obtained
  from Saturn's thermal emission spectra by using the retrieval algorithm
  Nemesis. The distribution of tropospheric phosphine and ammonia in gas
  phase will also be presented here. We managed to break the degeneracies
  inherent to the retrieval problem by analysing Saturn's thermal emission
  simultaneously at various viewing geometries. By using this method,
  we found that VIMS spectra at 4.5-5.1 microns are also sensitive to
  the hazes formed above the cloud layers. Saturn's reflected sunlight
  spectra at 0.8-3.5 microns measured with VIMS were also analysed in
  order to constrain the haze properties in the upper troposphere and
  lower stratosphere of the planet. Results from both the 0.8-3.5 and
  4.5-5.1 wavelength ranges were combined to determine the cloud and
  haze model most consistent with VIMS spectroscopy over a wide range of
  viewing geometries and lighting conditions. An increase of temperature
  below the tropopause, often referred to as the temperature knee,
  was retrieved from Cassini/CIRS spectra. Seasonal variations of the
  knee and haze structure are compared, and as a result the assumption
  of local heating by the hazes to explain this feature will be discussed.

---------------------------------------------------------
Title: Analysis Of Irtf Spex Near-infrared Observations Of Uranus:
    Aerosol Optical Properties And Latitudinally Variable Methane
Authors: Tice, Dane; Irwin, P. G. J.; Fletcher, L. N.; Teanby, N. A.;
   Hurley, J.; Orton, G. S.; Davis, G. R.
2012DPS....4441219T    Altcode:
  We present results from the analysis of near-infrared spectra of
  Uranus observed in August 2009 with the SpeX spectrograph at the NASA
  Infrared Telescope Facility (IRTF). Spectra range from 0.8 to 1.8
  μm at a spatial resolution of 0.5” and a spectral resolution of
  R = 1,200. This data is particularly well-suited to characterize the
  optical properties of aerosols in the Uranian stratosphere and upper
  troposphere. This is in part due to its coverage shortward of 1.0 μm
  where methane absorption, which dominates the features in the Uranian
  near-infrared spectrum, weakens slightly. Another particularly useful
  aspect of the data is it’s specific, highly spectrally resolved
  (R &gt; 4,000) coverage of the collision-induced hydrogen quadrupole
  absorption band at 825 nm, enabling us to differentiate between methane
  abundance and cloud opacity. An optimal-estimation retrieval code,
  NEMESIS, is used to analyze the spectra, and atmospheric models are
  developed that represent good agreement with data in the full spectral
  range analyzed. Aerosol single-scattering albedos that reveal a strong
  wavelength dependence will be discussed. Additionally, an analysis of
  latitudinal methane variability is undertaken, utilizing two methods
  of analysis. First, a reflectance study from locations along the
  central meridian is undertaken. The spectra from these locations
  are centered around 825 nm, where the collision-induced absorption
  feature of hydrogen is utilized to distinguish between latitudinal
  changes in the spectrum due to aerosol opacity and those due to
  methane variability. Secondly, high resolution retrievals from 0.8 -
  0.9 μm portion of the spectrum and spectral resolutions between R =
  4,000 and 4,500 are used to make the same distinction. Both methods
  will be compared and discussed, as will their indications supporting
  a methane enrichment in the equatorial region of the planet.

---------------------------------------------------------
Title: Seasonal Variations of Temperature, Acetylene and Ethane in
    Saturn's Stratosphere from 2005 to 2010
Authors: Sinclair, James; Irwin, P. G. J.; Fletcher, L. N.; Moses,
   J. I.; Greathouse, T. K.; Friedson, A. J.; Hesman, B.; Hurley, J.;
   Merlet, C.
2012DPS....4450003S    Altcode:
  Acetylene (C<SUB>2</SUB>H<SUB>2</SUB>) and ethane
  (C<SUB>2</SUB>H<SUB>6</SUB>) exemplify by-products of complex
  photochemistry in Saturn’s stratosphere. Their relative stability
  together with their strong vertical gradients in concentration allow
  for their use as tracers of vertical motion in Saturn’s lower
  stratosphere. Earlier studies of Saturn's hydrocarbons have provided
  only a snapshot of their behaviour with temporal variations remaining to
  be determined. In this study, we investigate how the thermal structure
  and concentrations of acetylene and ethane have evolved on Saturn
  with the changing season. We use FIRMAP (15.5 cm<SUP>-1</SUP> spectral
  resolution) Cassini-CIRS observations, initially retrieve temperature
  and subsequently retrieve the abundances of acetylene and ethane. In
  comparing 2005, 2009 and 2010 results, we observe the disappearance of
  Saturn's southern warm polar hood with cooling of up to 18.6 K ± 0.9 K
  at 1.1 mbar south of 75°S (planetographic). This suggests dissipation
  of Saturn's south polar vortex in addition to an autumnal cooling. We
  observe a 20% ± 9% enrichment of acetylene and a 30% ± 10% enrichment
  of ethane at 2.1 mbar at 25°N, together with a 14% ± 9% depletion of
  acetylene and an 18% ± 7% depletion of ethane at the same altitude at
  15°S. This suggests the presence of localised downwelling and upwelling
  at these latitudes, respectively. These vertical motions are consistent
  with a recently-developed GCM (global circulation model) of Saturn's
  tropopause and stratosphere, which predicts this pattern of upwelling
  and downwelling as a result of seasonally-reversing Hadley circulation.

---------------------------------------------------------
Title: Saturn’s Equatorial Plumes At Depth Observed By Cassini/VIMS
and Radar: Some Ammonia-wet, Some Dry
Authors: Baines, Kevin H.; Momary, T. W.; Janssen, M. A.; Ingersoll,
   A. P.; Fletcher, L. N.; Brown, R. H.; Buratti, B. J.; Clark, R. N.;
   Nicholson, P. D.; Sotin, C.
2012DPS....4450004B    Altcode:
  Large (&gt; 3000 km), discrete clouds and ammonia vapor features
  buried under Saturn’s ubiquotous equatorial haze have been
  mapped contemporaneously in Cassini/VIMS 5-micron spectra and 2-cm
  raster-scan imagery by the Cassini/RADAR used in passive mode. Since
  2008 these features have been clearly observed on four occasions -
  October 14-15, 2009, December 8-10, 2009, July 24-25, 2010, and
  March 19-21, 2011 - from a vantage point close to the knife-edge of
  the rings, which reduced the ring obscuration to just ± 3 degrees of
  latitude about the equator. Spectral modeling indicates that the cloud
  features are primarily located in the 2-3 bar region, and thus are
  likely to be comprised of ammonia hydrosulfide (NH4SH) with perhaps
  an admixture of water, but not of pure ammonia condensate. RADAR
  imagery reveals variations of the local ammonia humidity in the same
  2-3 bar region, assuming constant temperatures at depth to within
  a few degrees. Observations acquired March 19-21, 2011 clearly show
  correlations of ammonia-humid air with NH4SH cloud features, consistent
  with the idea that NH4SH clouds form from updrafts of ammonia-humid air,
  akin to the formation of convective water clouds on Earth in regions of
  high humidity. However, observations acquired December 8-10, 2009 show
  the opposite behavior, with localized cloud features largely coinciding
  with regions of low ammonia humidity. One possible explanation is
  that in the case of weaker updrafts, the rising NH3 is significantly
  depleted as it creates the NH4SH clouds, leaving ammonia-depleted holes
  in the background ammonia vapor. Alternatively, the supply of H2S in
  updrafts may vary relative to NH3, thus regulating the formation of
  both NH4SH aerosols and the left-over NH3 vapor. Finally, clouds in
  ammonia-dry regions may just indicate mature clouds no longer undergoing
  formation, as observed in the downwind “comet tail” clouds of the
  major northern storm of 2010-2011.

---------------------------------------------------------
Title: Line Positions, Intensities And Line Shape Parameters Of
    PH<SUB>3</SUB> Near 4.4 µm
Authors: Venkataraman, Malathy; Benner, D. C.; Kleiner, I.; Brown,
   L. R.; Sams, R. L.; Fletcher, L. N.
2012DPS....4441227V    Altcode:
  Accurate knowledge of spectral line parameters in the 2000 to
  2400 cm<SUP>-1</SUP> region of PH<SUB>3</SUB> is important for the
  CASSINI/VIMS exploration of dynamics and chemistry of Saturn and for the
  correct interpretation of future Jovian observations by JUNO and ESA’s
  newly-selected mission JUICE. Since the available intensity information
  for phosphine is inconsistent, we measured line positions and
  intensities for over 4000 individual transitions in the 2ν<SUB>2</SUB>,
  ν<SUB>2</SUB>+ν<SUB>4</SUB>, 2ν<SUB>4</SUB>, ν<SUB>1</SUB> and the
  ν<SUB>3</SUB> bands from analyzing high-resolution, high S/N spectra
  recorded at room temperature using two Fourier transform spectrometers
  (FTS); the Bruker IFS 125 HR FTS at PNNL and the Kitt Peak FTS at the
  National Solar Observatory in Arizona. In addition to line positions and
  intensities, self-broadened half width and self-induced pressure-shift
  coefficients were also measured for about 800 transitions for the
  various bands. The strong Coriolis and other types of interactions
  occurring among the various vibrational levels result in a large number
  of forbidden transitions as well as cause A+A- splittings in transitions
  with K″ that are multiples of 3. Line mixing was detected between
  several A+A- pairs of transitions; and self- line mixing coefficients
  were measured for several such pairs of transitions by applying the
  off-diagonal relaxation matrix formalism of Levy et al.<SUP>1</SUP> A
  multispectrum nonlinear least squares technique<SUP>2</SUP> employing a
  non-Voigt line shape including line mixing and speed dependence was used
  in fitting all the spectra simultaneously. Present results are compared
  with other reported values. This research is supported by NASA’s
  Outer Planets Research Program. References [1] A. Lévy et al., In
  “Spectroscopy of the Earth’s Atmosphere and Interstellar Medium”,
  Ed. K, Narahari Rao and A. Weber, Boston, Academic Press; p, 261-337
  (1992). [2] D. C. Benner et al., J Quant. Spectrosc. Radiat. Transfer
  53, 705, 1995.

---------------------------------------------------------
Title: Latitudinal Variation Of Upper Tropospheric NH3 On Saturn
    Derived From Cassini/cirs Far-infrared Measurements
Authors: Hurley, Jane; Fletcher, L. N.; Irwin, P. G. J.; Calcutt,
   S. B.; Sinclair, J. A.; Merlet, C.
2012DPS....4441212H    Altcode:
  Ammonia (NH3) has been detected both on Saturn and Jupiter, and although
  its concentration and distribution has been well-studied on Jupiter, it
  has proven more difficult to do so on Saturn due to higher sensitivity
  requirements resulting from Saturn’s lower atmospheric temperatures
  and the dominance of Saturn’s phosphine (PH3) which masks the NH3
  signal. Using far-infrared measurements of Saturn taken by Cassini/CIRS
  between February 2005 and December 2010, the latitudinal variations
  of upper tropospheric NH3 on Saturn are studied. Sensitivity to NH3
  in the far-infrared is explored to provide estimates of temperature,
  para-H2 and PH3, from 2.5 cm-1 spectral resolution measurements
  alone, 0.5 cm-1 spectral-resolution measurements alone, and 0.5 cm-1
  measurements degraded to 2.5 cm-1 spectral resolution. The estimates of
  NH3 from these three different datasets largely agree, although there
  are notable differences using the high emission angle 0.5 cm-1 data,
  which are asserted to result from a reduction in sensitivity at higher
  emission angles. For low emission angles, the 0.5 cm-1-retrieved values
  of NH3 can be used to reproduce the 2.5 cm-1 spectra with similar
  efficacy as those derived directly from the 2.5 cm-1 resolution data
  itself, and vice versa. Using low emission angle data, NH3 is observed
  to have broad peak abundances at ±25° latitude, attributed to result
  from condensation and/or photolytic processes. Lack of data coverage at
  equatorial latitudes precludes analysis of NH3 abundance at less than
  about 10° latitude. Noise levels are not sufficient to distinguish
  fine zonal features, although it seems that NH3 cannot trace the zonal
  belt/zone structure in the upper troposphere of Saturn.

---------------------------------------------------------
Title: Photochemistry in Saturn’s Ring Shadowed Atmosphere:
    Production Rates of Key Atmospheric Molecules and Haze Observations
Authors: Edgington, Scott G.; Atreya, S. K.; Wilson, E. H.; West,
   R. A.; Baines, K. H.; Bjoracker, G. L.; Fletcher, L. N.; Momary, T. W.
2012DPS....4441214E    Altcode:
  Cassini has been orbiting Saturn for over eight years. During this
  epoch, the ring shadow has moved from shading a large portion of
  the northern hemisphere (the ring plane was inclined by 24 degrees
  relative to the Sun-Saturn vector) to shading mid-latitudes south
  of the equator and continues southward. At its maximum extent,
  the projection of the ring plane shadow onto Saturn can reach as
  far as 48N ( 58N at the terminator). The net result, is that the
  intensity of both ultraviolet and visible sunlight penetrating onto
  any particular northern/southern latitude will vary depending on
  Saturn’s tilt relative to the Sun and the optical thickness of
  each ring system. Our previous work has examined the variation of
  the solar flux as a function of solar inclination, i.e. season on
  Saturn. Here we report on the impact of the oscillating ring shadow on
  the photolysis and production rates of key hydrocarbons in Saturn’s
  stratosphere and upper troposphere, including ethane, acetylene,
  propane, benzene. We investigate the impact on production and loss
  rates of the long-lived, photochemical hydrocarbons leading to haze
  formation at several latitudes over one Saturn year. Similarly, we
  assess the impact on the abundance of phosphine, a disequilibrium
  species whose presence in the upper troposphere is a tracer of
  convection processes in the deep atmosphere. Along with the above,
  we present preliminary analysis of Cassini’s UVIS and VIMS datasets
  that provide an estimate of the evolving haze content of the northern
  hemisphere. The research described in this paper was carried out at
  the Jet Propulsion Laboratory, California Institute of Technology,
  under a contract with the National Aeronautics and Space Administration.

---------------------------------------------------------
Title: Seasonal And Non-seasonal Variations Of Jupiter’s Atmosphere
    From Observations Of Thermal Emission, 1994-2011
Authors: Orton, Glenn S.; Fletcher, L.; Yanamandra-Fisher, P.;
   Greathouse, T.; Fisher, B.; Greco, J.; Wakefield, L.; Snead, E.;
   Boydstun, K.; Arzumanyan, G.; Christian, J.
2012DPS....4450001O    Altcode:
  We analyzed mid-infrared images of Jupiter’s thermal emission,
  covering 1.5 Jovian years, acquired in discrete filters between 7.8 and
  24.5 μm. The behavior of stratospheric ( 10-mbar) and tropospheric (
  100-400 mbar) temperatures is generally consistent with predictions of
  seasonal variability, with differences between 100-mbar temperatures
  ±50-60° from the equator on the order of ±2 K. Removing this effect,
  there appear to be long-term periodicities of tropospheric temperatures,
  with amplitude, phase and period dependent on latitude. Temperatures
  near and south of the equator vary least (&lt; ±1 K). At some
  higher latitudes, the amplitudes vary by as much as ±2.5 K with peak
  periodicities still showing a 12-year signature with other periods
  ranging from 3 to 8 years. The 4-year variation of stratospheric
  temperatures known as the quasi-quadrennial oscillation or “QQO”
  (Leovy et al. 1991, Nature 354, 380) continued during this period. There
  were no variations of zonal mean temperatures associated with any of
  the “global upheaval” events that have produced dramatic changes
  of Jupiter’s visible appearance and cloud cover, although there
  are colder discrete regions associated with updrafts, e.g. the early
  stages of the re-darkening (“revival”) of the South Equatorial Belt
  (SEB) in late 2010. On the other hand increases in the visible albedos
  (“fades”) of belts are accompanied by increases in cloudiness at 700
  mbar (most likely an NH3 ice cloud layer) and higher pressures, together
  with the mixing ratio of NH<SUB>3</SUB> gas near 400 mbar (above its
  condensation level). These quantities decrease during re-darkening
  (“revival”) episodes, during which we note exceptions to the
  general correlation between dark albedos and minimal cloudiness. In
  contrast to all these changes, the meridional distribution of the
  240-mbar para-H<SUB>2</SUB> fraction appears to be time-invariant.

---------------------------------------------------------
Title: Variation of solar oscillation frequencies in solar cycle 23
    and their relation to sunspot area and number
Authors: Jain, R.; Tripathy, S. C.; Watson, F. T.; Fletcher, L.;
   Jain, K.; Hill, F.
2012A&A...545A..73J    Altcode:
  <BR /> Aims: Studying the long term evolution of the solar acoustic
  oscillations is necessary for understanding how the large-scale solar
  dynamo operates. In particular, an understanding of the solar cycle
  variation in the frequencies of solar oscillations can provide a
  powerful diagnostic tool for constraining various dynamo models. In
  this work, we report the temporal evolution of solar oscillations
  for the solar cycle 23, and correlate with solar magnetic activity
  indices. <BR /> Methods: We use solar oscillation frequencies obtained
  from the Michelson Doppler Imager on board the Solar and Heliospheric
  Observatory, correlate them with the sunspot number provided by the
  international sunspot number, R<SUB>I</SUB>, and compare them with the
  sunspot number calculated with the Sunspot Tracking And Recognition
  Algorithm (STARA). <BR /> Results: We find that the mean frequency
  shifts correlate very well with the sunspot numbers obtained from
  two different datasets. We also find a hysteresis-type behaviour
  for the STARA sunspot area and mean magnetic field strength for the
  different phases of the solar cycle. The increase in solar oscillation
  frequencies precedes slightly the increase in total sunspot area and
  the mean magnetic field strength for the solar cycle 23. We briefly
  discuss the cyclic behaviour in the context of p-mode frequencies.

---------------------------------------------------------
Title: Habitability of the giant icy moons: current knowledge and
    future insights from the JUICE mission
Authors: Grasset, O.; Prieto-Ballesteros, O.; Titov, D.; Erd, C.;
   Bunce, E.; Coustenis, A.; Blanc, M.; Coates, A.; Fletcher, L.; van
   Hoolst, T.; Hussmann, H.; Jaumann, R.; Krupp, N.; Tortora, P.; Tosi,
   F.; Wielders, A.
2012epsc.conf..925G    Altcode: 2012espc.conf..925G
  Large satellites of gas giants, at orbits beyond the snow-line, such
  as Jupiter or Saturn, can contain a large amount of water (almost 45%
  in mass). Hydrospheres are extremely thick, ~600 km for Ganymede and
  Callisto, and may possess liquid layers below the icy crust. Thus,
  the Galilean satellites provide a conceptual basis within which new
  theories for understanding habitability can be constructed. Measurements
  from the Voyager and Galileo spacecraft revealed the potential of these
  satellites in this context. The JUpiter Icy moons Explorer (JUICE) will
  greatly enhance our understanding of their potential habitability. It
  is known, even at Earth where life mostly depends on solar energy,
  that habitats exist deep in the oceans in eternal darkness feeding on
  chemical energy. Aqueous layers are suspected below the icy crusts
  of the moons, which possess similar physical characteristics than
  Earth's deep oceans. Since they are certainly very stable through time,
  and because complex chemistry and energy sources may be available,
  life may have originated within such subsurface habitats despite the
  hostile surface conditions. Liquid water reservoirs have been proposed
  on Ganymede, Europa and Callisto from geophysical models, based on
  Galileo observations. These oceans that are covered by ice shells
  exist independently of the input of stellar energy, and are located
  well outside the conventional habitable zone of the Sun. Considering
  the pressure range encountered within the icy moons, four different
  scenarios can be defined. These result from varying thicknesses of the
  water ice layers and the liquid ocean with respect to the silicate floor
  (Figure 1). Case 2 in Figure 1 is highly probable for the largest moons
  (Ganymede and Callisto), while case 3 is more probable for Europa
  and smaller icy moons if they host liquid reservoirs such as has been
  discovered at Enceladus. Europa's ocean is unique because it may be in
  contact with the rock layer. This substrate may be geologically active
  and affected by hydrothermal processes, similar to the terrestrial
  sea floor. This may enhance habitability conditions since the rock
  layer could release chemical elements and energy to the surrounding
  water ocean. Differentiation of the rock could be responsible for
  the presence of salts and other essential elements in the ocean, and
  produce the low albedo terrains seen on the surface. An estimation of
  the minimal thickness of the icy crust over the most active regions of
  Europa is among the measurement goals of JUICE and this will provide
  important constraints on the subsurface structure of the moon. On the
  larger icy moons, Ganymede and Callisto, where internal pressures are
  sufficient to allow for the formation of high pressure ice phases,
  the existence of an ocean suggests that it should be enclosed between
  thick ice layers. Chemical and energy exchanges between the rocky
  layer and the ocean, which are so important for habitability, cannot
  be ruled out but would imply efficient transport processes through the
  thick high pressure icy layer. Such processes are indeed possible but
  not as clearcut as the exchanges that can be envisaged for Europa. Icy
  and liquid layers are probably not solely constituted of pure H2O. Many
  other compounds such as salts, or CO2 have been observed on the surfaces
  and may emerge from the deep interiors of the moons. Volatiles, organics
  and minerals solidified from the aqueous cryo-magmas, could be detected
  remotely from an orbiting spacecraft. Analysis of these materials
  will give great insight to the physico-chemistry and composition
  of the deep environments. But such organic matter and other surface
  compounds will experience a different radiation environment at Europa
  than at Ganymede (due to the difference in radial distance from Jupiter)
  and thus may suffer different alteration processes, influencing their
  detection on the surface. Measurements from terrains on both Europa
  and Ganymede will allow a comparison of different radiation doses and
  terrain ages from similar materials. JUICE will address key areas that
  emerge in the study of habitable worlds around gas giants including
  constraints on the volume of liquid water in the Jovian system. The
  mission will also establish the inventory of biologically essential
  elements on the surfaces of the icy moons, and determine the magnitude
  of their transport among the moons which exchange material as a result
  of volcanism, sputtering, and impacts. The mission may also allow us
  to infer environmental properties such as the pH, salinity, and water
  activity of the oceans and will investigate the effects of radiation
  on the detectability of surface organics.

---------------------------------------------------------
Title: Temperature Structure and Composition of Uranus Derived from
    Observations by ISO, Spitzer, Herschel, and Ground-Based Telescopes
    Coupled with Photochemical Models
Authors: Orton, G.; Fletcher, L.; Feuchtgruber, H.; Lellouch, E.;
   Moreno, R.; Encrenaz, T.; Hartogh, P.; Jarchow, C.; Moses, J.;
   Burgdorg, M.; Hammel, H.; Line, M.; Mainzer, A.; Hofstadter, M.;
   Sandell, G.; Dowell, D.
2012epsc.conf..289O    Altcode: 2012espc.conf..289O
  The combined power of absolutely calibrated photometry and spectroscopy
  of Uranus has been combined to create self-consistent models of
  its global-mean temperature profile, bulk composition, and vertical
  distribution of gases.

---------------------------------------------------------
Title: The Evolution of Saturn's Stratospheric Beacon 2011-2012
Authors: Fletcher, L. N.; Hesman, B. E.; Achterberg, R. K.; Bjoraker,
   G.; Gorius, N.; Irwin, P. G. J.; Hurley, J.; Sinclair, J.; Orton,
   G. S.; Read, P. L.; Flasar, F. M.; Legarreta, J.; Garcia-Melendo,
   E.; Sanchez-Lavega, A.
2012epsc.conf..313F    Altcode: 2012espc.conf..313F
  The slow warming of Saturn's springtime stratosphere was spectacularly
  disrupted in 2010 by the eruption of a planetary-scale tropospheric
  storm system [1-3]. The roiling, convective motions of the tropospheric
  cloud decks had a dramatic influence on the atmospheric temperatures
  and composition many hundreds of kilometers higher up, in Saturn's
  stably stratified middle atmosphere. Energy transported from the
  tropospheric storm was deposited in two warm stratospheric airmasses,
  known as beacons B1 and B2 because of their brightness in thermal
  infrared imaging. These features were observed throughout 2011 and
  2012 using a combination of 7- 1000 μm spectroscopic mapping from
  the Cassini Composite Infrared Spectrometer (CIRS, [1]) and filtered
  7-25 μm imaging from the VLT/VISIR and IRTF/MIRSI thermal-infrared
  instruments. These infrared observations are used to discuss the
  motions, temperatures, composition, winds and stability of these newly
  discovered phenomena in Saturn's stratosphere.

---------------------------------------------------------
Title: Examining Rotational Variability in the Upper Tropospheres
    and Lower Stratospheres of Uranus and Neptune from Herschel PACS
    OT1 Observations
Authors: Orton, G.; Feuchtgruber, H.; Fletcher, L.; Lellouch, E.;
   Moreno, R.; Encrenaz, T.; Billebaud, F.; Cavalie, T.; Dobreijevcic,
   M.; Decin, L.; Hartogh, P.; Jarchow, C.; Lara, L. M.; Liu, J.
2012epsc.conf..867O    Altcode: 2012espc.conf..867O
  The power of high-resolution submillimeter spectroscopy of Uranus
  and Neptune was put to use to survey the rotational variability of
  stratospheric and tropospheric constituents of their atmospheres.

---------------------------------------------------------
Title: Exploring the Atmospheres of the Ice Giants
Authors: Fletcher, L. N.; Orton, G. S.; Hofstadter, M.; Irwin,
   P. G. J.; de Pater, I.
2012epsc.conf..862F    Altcode: 2012espc.conf..862F
  Of all the planets in our solar system, the two ice giants Uranus
  and Neptune remain the least explored and poorly understood because
  of their great distance from Earth. And yet they occupy a unique
  position in the hierarchy of planetary types, being intermediate
  between gas giants with their enormous hydrogen-helium envelopes, and
  terrestrial-sized worlds and Super Earths. These ice giants, so-called
  because their bulk compositions are dominated by heavier elements,
  are a true frontier of our exploration of planetary atmospheres,
  having been visited only once by Voyager 2 in 1986 and 1989, and may
  be representative of a whole class of planetary objects throughout our
  galaxy. Even though Earth-based observations (ISO, Spitzer, Herschel,
  ground-based) have improved dramatically in the decades since Voyager 2,
  many questions about this unexplored region of our Solar System remain
  unanswered. Voyager revealed unexpected differences in the appearance,
  composition, dynamics and chemistry between these two worlds, which
  could ultimately help us to understand how planetary atmospheres form
  and evolve as a function of distance from their host stars. This talk
  will review our present understanding of ice giant atmospheres, and
  assess the key questions to be answered by future exploration.

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Title: The application of new methane line absorption data to
    Gemini-N/NIFS and KPNO/FTS observations of Uranus' near-infrared
    spectrum
Authors: Irwin, P. G. J.; de Bergh, C.; Courtin, R.; Bézard, B.;
   Teanby, N. A.; Davis, G. R.; Fletcher, L. N.; Orton, G. S.; Calcutt,
   S. B.; Tice, D.; Hurley, J.
2012Icar..220..369I    Altcode:
  New line data describing the absorption of CH<SUB>4</SUB> and
  CH<SUB>3</SUB>D from 1.26 to 1.71 μm (Campargue, A., Wang, L.,
  Mondelain, D., Kassi, S., Bézard, B., Lellouch, E., Coustenis,
  A., de Bergh, C., Hirtzig, M., Drossart, P. [2012]. Icarus
  219, 110-128), building upon previous papers by Campargue
  et al. (Campargue, A., Wang, L., Kassi, S., Masat, M.,
  Votava, O. [2010]. J. Quant. Spectrosc. Radiat. Transfer
  111, 1141-1151; Wang, L., Kassi, S., Campargue,
  A. [2010]. J. Quant. Spectrosc. Radiat. Transfer 111,
  1130-1140; Wang, L., Kassi, S., Liu, A.W., Hu, S.M., Campargue,
  A. [2011]. J. Quant. Spectrosc. Radiat. Transfer 112, 937-951)) have
  been applied to the analysis of Gemini-N/NIFS observations of Uranus
  made in 2010 and compared with earlier disc-averaged observations
  made by KPNO/FTS in 1982. The new line data are found to improve
  greatly the fit to the observed spectra and present a huge advance
  over previous methane absorption tables by allowing us to determine
  the CH<SUB>3</SUB>D/CH<SUB>4</SUB> ratio and also start to break the
  degeneracy between methane abundance and cloud top height. The best
  fits are obtained if the cloud particles in the main cloud deck at
  the 2-3 bar level become less scattering with wavelength across the
  1.4-1.6 μm region and we have modelled this variation here by varying
  the extinction cross-section and single-scattering albedo of the
  particles. Applying the new line data to the NIFS spectra of Uranus,
  we determine a new estimate of the CH<SUB>3</SUB>D/CH<SUB>4</SUB>
  ratio of 2.9-0.5+0.9×10<SUP>-4</SUP>, which is consistent with
  the estimate of de Bergh et al. (de Bergh, C., Lutz, B.L., Owen,
  T., Brault, J., Chauville, J. [1986]. Astrophys. J. 311, 501-510)
  of 3.6-2.8+3.6×10<SUP>-4</SUP>, made by fitting a disc-averaged
  KPNO/FTS spectrum measured in 1982, but much better constrained. The
  NIFS observations made in 2010 have been disc-averaged and compared with
  the 1982 KPNO/FTS spectrum and found to be in excellent agreement. Using
  k-tables fitted to the new line data, the central meridian observations
  of Uranus' H-band spectrum (1.49-1.64 μm) made by Gemini-N/NIFS in 2010
  have been reanalyzed. The use of the new methane absorption coefficients
  and the modified scattering properties of the cloud particles in the
  main cloud deck appears to break the degeneracy between cloud height and
  methane abundance immediately above it in this spectral region and we
  find that both vary with latitude across Uranus' disc. Overall, we find
  that the main cloud deck becomes higher, but thinner from equator to
  poles, with a local maximum in cloud top height in the circumpolar zones
  at 45°N and 45°S. At the same time, using the 'D' temperature pressure
  profile of Lindal et al. (Lindal, G.F., Lyons, J.R., Sweetnam, D.N.,
  Eshleman, V.R., Hinson, D.P. [1987]. J. Geophys. Res. 92, 14987-15001)
  and a deep methane abundance of 1.6% (Baines, K.H., Mickelson, M.E.,
  Larson, L.E., Ferguson, D.W. [1995]. Icarus 144, 328-340) we find that
  the relative humidity of methane is high near the equator (∼60%) and
  decreases sharply towards the poles, except near the circumpolar zone
  at 45°N, which has brightened steadily since 2007, and where there is
  a local maximum in methane relative humidity. In tests conducted with
  the warmer 'F1' profile of Sromovsky et al. (2011) we find a similar
  variation of methane abundance above the main cloud, although for this
  warmer temperature profile this abundance is dependent mostly on the
  fitted deep methane mole fraction.

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Title: Charge-exchange Limits on Low-energy α-particle Fluxes in
    Solar Flares
Authors: Hudson, H. S.; Fletcher, L.; MacKinnon, A. L.; Woods, T. N.
2012ApJ...752...84H    Altcode: 2014arXiv1401.6477H
  This paper reports on a search for flare emission via charge-exchange
  radiation in the wings of the Lyα line of He II at 304 Å, as
  originally suggested for hydrogen by Orrall &amp; Zirker. Via this
  mechanism a primary α particle that penetrates into the neutral
  chromosphere can pick up an atomic electron and emit in the He
  II bound-bound spectrum before it stops. The Extreme-ultraviolet
  Variability Experiment on board the Solar Dynamics Observatory gives
  us our first chance to search for this effect systematically. The
  Orrall-Zirker mechanism has great importance for flare physics because
  of the essential roles that particle acceleration plays; this mechanism
  is one of the few proposed that would allow remote sensing of primary
  accelerated particles below a few MeV nucleon<SUP>-1</SUP>. We study
  10 events in total, including the γ-ray events SOL2010-06-12 (M2.0)
  and SOL2011-02-24 (M3.5) (the latter a limb flare), seven X-class
  flares, and one prominent M-class event that produced solar energetic
  particles. The absence of charge-exchange line wings may point to a
  need for more complete theoretical work. Some of the events do have
  broadband signatures, which could correspond to continua from other
  origins, but these do not have the spectral signatures expected from
  the Orrall-Zirker mechanism.

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Title: Line Parameters of the PH_3 Pentad in the 4-5 μm Region
Authors: Devi, V. Malathy; Benner, D. Chris; Kleiner, I.; Sams, R. L.;
   Blake, T. A.; Brown, Linda R.; Fletcher, L. N.
2012mss..confEFA08D    Altcode:
  Line positions, intensities and line shape parameters are reported
  for four bands of phosphine between 2150 and 2400 cm<SUP>-1</SUP>
  in order to improve the spectroscopic database for remote sensing
  of the giant planets. Knowledge of PH_3 in this spectral region is
  important for Cassini/VIMS exploration of dynamics and chemistry on
  Saturn, as well as for interpreting the near-IR data from Juno and
  ESA's proposed Jupiter mission. For this study, five high-resolution
  (0.0023 cm<SUP>-1</SUP>), high signal-to-noise (&gt;2000) spectra of
  pure PH_3 were recorded at room temperature (298.2 K) with the Bruker
  IFS 125HR Fourier transform spectrometer at Pacific Northwest National
  Laboratory. Individual line parameters were retrieved by multispectrum
  fitting of all five spectra simultaneously. Positions and intensities
  were measured for over 3100 transitions. The rotational quantum numbers
  of measured lines go as high as J”=16 and K”=15 in the ν_3 and
  ν_1 bands; some lines of the weaker bands 2ν_4 and ν_2+ν_4 are
  also reported. The measured positions and intensities are compared
  to new theoretical calculations of the pentad. Lorentz self-broadened
  width and pressure-induced shift coefficients of many transitions were
  also obtained, along with speed dependence parameters. Line mixing
  coefficients were determined for several A<SUP>+</SUP>A<SUP>-</SUP>
  pairs of transitions for K”=3, 6, and 9. <P />Research described in
  this paper was performed at the College of William and Mary and the
  Jet Propulsion Laboratory, California Institute of Technology, under
  contracts and cooperative agreements with the National Aeronautics and
  Space Administration. L. Fletcher acknowledges support from a Glasstone
  Science Fellowship. <P />D. C. Benner, C. P. Rinsland, V. Malathy Devi,
  M. A. H. Smith and D. A. Atkins, JQSRT 53 (1995) 705-721.

---------------------------------------------------------
Title: Numerical Simulations of Chromospheric Hard X-Ray Source
    Sizes in Solar Flares
Authors: Battaglia, M.; Kontar, E. P.; Fletcher, L.; MacKinnon, A. L.
2012ApJ...752....4B    Altcode: 2012arXiv1204.1151B
  X-ray observations are a powerful diagnostic tool for transport,
  acceleration, and heating of electrons in solar flares. Height and
  size measurements of X-ray footpoint sources can be used to determine
  the chromospheric density and constrain the parameters of magnetic
  field convergence and electron pitch-angle evolution. We investigate
  the influence of the chromospheric density, magnetic mirroring, and
  collisional pitch-angle scattering on the size of X-ray sources. The
  time-independent Fokker-Planck equation for electron transport is
  solved numerically and analytically to find the electron distribution
  as a function of height above the photosphere. From this distribution,
  the expected X-ray flux as a function of height, its peak height, and
  full width at half-maximum are calculated and compared with RHESSI
  observations. A purely instrumental explanation for the observed
  source size was ruled out by using simulated RHESSI images. We find
  that magnetic mirroring and collisional pitch-angle scattering tend
  to change the electron flux such that electrons are stopped higher in
  the atmosphere compared with the simple case with collisional energy
  loss only. However, the resulting X-ray flux is dominated by the
  density structure in the chromosphere and only marginal increases in
  source width are found. Very high loop densities (&gt;10<SUP>11</SUP>
  cm<SUP>-3</SUP>) could explain the observed sizes at higher energies,
  but are unrealistic and would result in no footpoint emission below
  about 40 keV, contrary to observations. We conclude that within
  a monolithic density model the vertical sizes are given mostly by
  the density scale height and are predicted smaller than the RHESSI
  results show.

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Title: Flare Ribbons In The Early Phase Of An SDO Flare: Emission
    Measure And Energetics
Authors: Fletcher, Lyndsay; Hannah, I. G.; Hudson, H. S.; Innes, D. E.
2012AAS...22050902F    Altcode:
  We report on the M1.0 flare of 7th August 2010, which displayed
  extended early phase chromospheric ribbons, well observed by SDO/AIA
  and RHESSI. Most large flares saturate rapidly in the high-temperature
  AIA channels, however this event could be followed in unsaturated AIA
  images for ten minutes in the build-up to and first few minutes of the
  impulsive phase. Analysis of GOES, RHESSI and SDO/AIA demonstrates
  the presence of high temperature ( 10MK), compact plasma volumes in
  the chromospheric flare ribbons, with a column emission measure of
  on average 3-7 x 10<SUP>28</SUP> cm<SUP>-5</SUP>. We construct a
  time-resolved energy budget for the ribbon plasma, including also
  SDO/EVE data, and discuss the implications of the observed ribbon
  properties for flare energisation. <P />This work was supported by
  the UK’s Science and Technology Facilities Council (ST/1001801),
  and by the European Commission through the FP7 HESPE project
  (FP7-2010-SPACE-263086).

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Title: Solar Flare Observations of the EUV Continua
Authors: Milligan, Ryan O.; Chamberlin, P.; Hudson, H.; Woods, T.;
   Mathioudakis, M.; Fletcher, L.; Kowalski, A.; Keenan, F.
2012AAS...22052105M    Altcode:
  Recent solar flare simulations suggest that the energy deposited in the
  chromosphere by nonthermal electrons during a flare's impulsive phase
  is re-emitted in the form of recombination (free-bound) continua, in
  particular, the Lyman, Balmer, and Paschen continua of hydrogen, and
  the He I and He II continua (Allred et al. 2005). However, definitive
  observations of free-bound emission during solar flares have been scarce
  in recent years as many modern, space-based instruments do not have
  the required sensitivity, wavelength coverage, or duty cycle. With
  the launch of SDO, these observations are now routinely available
  thanks to the EUV Variability Experiment (EVE) instrument. Here we
  present unambiguous, spectrally and temporally resolved detections of
  enhanced free-free and free-bound continua during the first X-class
  solar flare of Solar Cycle 24. While we find that the flare energy
  in the EVE spectral range amounts to at most a few percent of the
  total flare energy, these findings highlight the capability of EVE
  in giving us the first comprehensive look at these diagnostically
  important continuum components.

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Title: Solar Chromospheric Flares: Energy Release, Transport and
    Radiation
Authors: Fletcher, L.
2012ASPC..456..183F    Altcode: 2012arXiv1207.0384F
  This paper presents an overview of some recent observational and
  theoretical results on solar flares, with an emphasis on flare
  impulsive-phase chromospheric properties, including: electron
  diagnostics, optical and UV emission, and discoveries made by the
  Hinode mission, especially in the EUV. A brief perspective on future
  observations and theoretical requirements is also given.

---------------------------------------------------------
Title: Dynamical Heating In Flares Observed With SDO/AIA &amp; RHESSI
Authors: Hannah, Iain; Fletcher, L.; Kontar, E. P.
2012AAS...22032202H    Altcode:
  The spatial and temporal resolution of SDO/AIA data presents an
  unprecedented view of the dynamics of heating during solar flares. This
  combined with the non-thermal energetics from RHESSI hard X-ray imaging
  and spectroscopy provides constraints on the flaring energy release. The
  recently implemented regularized inversion method (Hannah &amp; Kontar
  A&amp;A 2012) robustly recovers the underlying thermal distribution (the
  Differential Emission Measure, DEM) of the coronal plasma from SDO/AIA
  images. Crucially it is not limited to the isothermal or Gaussian-model
  approximation that some other approaches depend upon. Our method
  provides the uncertainties in the DEM and is computationally quick,
  producing DEMs per pixel for a series of SDO/AIA images allowing
  temperature maps and movies to be created. We use the regularized
  inversion method to study the temporal and spatial evolution of the
  plasma heating in flares and show how the non-thermal energy relates
  to this. We also investigate how the calibration errors/uncertainties
  affect the inferred DEMs and errors.

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Title: Observations of upper tropospheric acetylene on Saturn:
    No apparent correlation with 2000 km-sized thunderstorms
Authors: Hurley, J.; Irwin, P. G. J.; Fletcher, L. N.; Moses, J. I.;
   Hesman, B.; Sinclair, J.; Merlet, C.
2012P&SS...65...21H    Altcode:
  Thunderstorm activity has been observed on Saturn via radio
  emissions from lightning discharges and optical detections of the
  lightning flashes on the planet's nightside. Thunderstorms provide
  extreme environments in which specific atmospheric chemistry can be
  induced-namely through energy release via lightning discharges, and
  fast vertical transport resulting in rapid advection of tropospheric
  species. It is thus theorised that certain atmospheric trace species -
  such as C<SUB>2</SUB>H<SUB>2</SUB>, HCN, and CO - can be generated in
  the troposphere by large bursts of energy in the form of lightning,
  and transported upward towards the upper troposphere by the extreme
  dynamics of thunderstorms, where they should be observable by satellite
  instruments. In this work, high-spectral-resolution Cassini/CIRS
  observations from October 2005 through April 2009 are used to
  study whether there is an observable increase in upper tropospheric
  acetylene in regions of known normal thunderstorm activity. Using both
  individual measurements in which there is known thunderstorm activity,
  as well as large coadditions of data to study latitudinal-dependencies
  over the full disc, no systematic enhancement in upper tropospheric
  (100 mbar) C<SUB>2</SUB>H<SUB>2</SUB> was detected around regions
  in which there are known occurrences of normally sized (2000 km)
  thunderstorms, or in normally sized thunderstorm-prone regions such as
  40°S. It is likely that the magnitude of the enhancement theorised
  is too generous or that enhancements are not advected into the upper
  troposphere as vertical mixing rates in models would suggest, since
  Cassini/CIRS can only detect C<SUB>2</SUB>H<SUB>2</SUB> above the
  200 mbar level-although the massive northern hemisphere thunderstorm
  of 2010/2011 seems able to decrease stratospheric concentrations
  of C<SUB>2</SUB>H<SUB>2</SUB>. From this, it can be asserted that
  lightning from normal thunderstorm activity cannot be the key
  source for upper tropospheric C<SUB>2</SUB>H<SUB>2</SUB> on Saturn,
  since the upper-tropospheric concentrations retrieved agree with the
  concentrations stemming from the photolysis of CH<SUB>4</SUB> (2-3 ppbv)
  from solar radiation penetrating through the Saturnian atmosphere,
  with an upper limit for lightning-induced C<SUB>2</SUB>H<SUB>2</SUB>
  volume mixing ratio of 10<SUP>-9</SUP>.

---------------------------------------------------------
Title: Investigating the Structure of Impulsive Phase Footpoints
Authors: Graham, David; Hannah, I.; Fletcher, L.; Milligan, R.
2012AAS...22050903G    Altcode:
  The location of flare heating in the solar atmosphere is imperative
  to understanding the heating mechanism. The differential emission
  measure is an important tool in understanding the properties of flaring
  plasma. However, determining the DEM of impulsive phase footpoints
  has been difficult in the past without sufficient spatial resolution
  to resolve footpoints from loop structures, and a lack of spectral
  and temporal coverage. We use the capabilities of Hinode/EIS to
  present the first DEMs from the impulsive phase of a number of flare
  footpoints. Observations were chosen from a period when EIS telemetry
  was at its best and analysed using a new regularised inversion method
  (Hannah &amp; Kontar 2012). We find a peak temperature in the DEM
  of around 7 MK with emission measures peaking between 10^28 and
  10^29 cm-5, indicating a substantial presence of plasma at 'coronal'
  temperatures within the footpoint. In addition to the DEM, we perform
  a wide range of density diagnostics from transition region to coronal
  temperatures, allowing us estimate where in the atmosphere the EUV
  emission originates.

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Title: Break up of returning plasma after the 7 June 2011 filament
    eruption by Rayleigh-Taylor instabilities
Authors: Innes, D. E.; Cameron, R. H.; Fletcher, L.; Inhester, B.;
   Solanki, S. K.
2012A&A...540L..10I    Altcode: 2012arXiv1202.4981I
  Context. A prominence eruption on 7 June 2011 produced spectacular
  curtains of plasma falling through the lower corona. At the solar
  surface they created an incredible display of extreme ultraviolet
  brightenings. <BR /> Aims: To identify and analyze some of the local
  instabilities which produce structure in the falling plasma. <BR />
  Methods: The structures were investigated using SDO/AIA 171 Å and
  193 Å images in which the falling plasma appeared dark against
  the bright coronal emission. <BR /> Results: Several instances of
  the Rayleigh-Taylor instability were investigated. In two cases the
  Alfvén velocity associated with the dense plasma could be estimated
  from the separation of the Rayleigh-Taylor fingers. A second type of
  feature, which has the appearance of self-similar branching horns was
  discussed. <P />Appendix A and two movies are available in electronic
  form at <A href="http://www.aanda.org">http://www.aanda.org</A>

---------------------------------------------------------
Title: Commission 10: Solar Activity
Authors: van Driel-Gesztelyi, Lidia; Schrijver, Carolus J.; Klimchuk,
   James A.; Charbonneau, Paul; Fletcher, Lyndsay; Hasan, S. Sirajul;
   Hudson, Hugh S.; Kusano, Kanya; Mandrini, Cristina H.; Peter, Hardi;
   Vršnak, Bojan; Yan, Yihua
2012IAUTA..28...69V    Altcode:
  Commission 10 of the International Astronomical Union has more than
  650 members who study a wide range of activity phenomena produced by
  our nearest star, the Sun. Solar activity is intrinsically related
  to solar magnetic fields and encompasses events from the smallest
  energy releases (nano- or even picoflares) to the largest eruptions
  in the Solar System, coronal mass ejections (CMEs), which propagate
  into the Heliosphere reaching the Earth and beyond. Solar activity is
  manifested in the appearance of sunspot groups or active regions, which
  are the principal sources of activity phenomena from the emergence of
  their magnetic flux through their dispersion and decay. The period
  2008-2009 saw an unanticipated extended solar cycle minimum and
  unprecedentedly weak polar-cap and heliospheric field. Associated with
  that was the 2009 historical maximum in galactic cosmic rays flux since
  measurements begun in the middle of the 20th Century. Since then Cycle
  24 has re-started solar activity producing some spectacular eruptions
  observed with a fleet of spacecraft and ground-based facilities. In
  the last triennium major advances in our knowledge and understanding
  of solar activity were due to continuing success of space missions as
  SOHO, Hinode, RHESSI and the twin STEREO spacecraft, further enriched
  by the breathtaking images of the solar atmosphere produced by the
  Solar Dynamic Observatory (SDO) launched on 11 February 2010 in the
  framework of NASA's Living with a Star program. In August 2012, at the
  time of the IAU General Assembly in Beijing when the mandate of this
  Commission ends, we will be in the unique position to have for the
  first time a full 3-D view of the Sun and solar activity phenomena
  provided by the twin STEREO missions about 120 degrees behind and
  ahead of Earth and other spacecraft around the Earth and ground-based
  observatories. These new observational insights are continuously
  posing new questions, inspiring and advancing theoretical analysis
  and modelling, improving our understanding of the physics underlying
  magnetic activity phenomena. Commission 10 reports on a vigorously
  evolving field of research produced by a large community. The number
  of refereed publications containing `Sun', `heliosphere', or a synonym
  in their abstracts continued the steady growth seen over the preceding
  decades, reaching about 2000 in the years 2008-2010, with a total of
  close to 4000 unique authors. This report, however, has its limitations
  and it is inherently incomplete, as it was prepared jointly by the
  members of the Organising Committee of Commission 10 (see the names
  of the primary contributors to the sections indicated in parentheses)
  reflecting their fields of expertise and interest. Nevertheless, we
  believe that it is a representative sample of significant new results
  obtained during the last triennium in the field of solar activity.

---------------------------------------------------------
Title: Solar Particle Acceleration Radiation and Kinetics (SPARK). A
    mission to understand the nature of particle acceleration
Authors: Matthews, Sarah A.; Williams, David R.; Klein, Karl-Ludwig;
   Kontar, Eduard P.; Smith, David M.; Lagg, Andreas; Krucker, Sam;
   Hurford, Gordon J.; Vilmer, Nicole; MacKinnon, Alexander L.; Zharkova,
   Valentina V.; Fletcher, Lyndsay; Hannah, Iain G.; Browning, Philippa
   K.; Innes, Davina E.; Trottet, Gerard; Foullon, Clare; Nakariakov,
   Valery M.; Green, Lucie M.; Lamoureux, Herve; Forsyth, Colin; Walton,
   David M.; Mathioudakis, Mihalis; Gandorfer, Achim; Martinez-Pillet,
   Valentin; Limousin, Olivier; Verwichte, Erwin; Dalla, Silvia; Mann,
   Gottfried; Aurass, Henri; Neukirch, Thomas
2012ExA....33..237M    Altcode: 2011ExA...tmp..124M
  Energetic particles are critical components of plasma populations
  found throughout the universe. In many cases particles are accelerated
  to relativistic energies and represent a substantial fraction of
  the total energy of the system, thus requiring extremely efficient
  acceleration processes. The production of accelerated particles
  also appears coupled to magnetic field evolution in astrophysical
  plasmas through the turbulent magnetic fields produced by diffusive
  shock acceleration. Particle acceleration is thus a key component
  in helping to understand the origin and evolution of magnetic
  structures in, e.g. galaxies. The proximity of the Sun and the range
  of high-resolution diagnostics available within the solar atmosphere
  offers unique opportunities to study the processes involved in particle
  acceleration through the use of a combination of remote sensing
  observations of the radiative signatures of accelerated particles, and
  of their plasma and magnetic environment. The SPARK concept targets the
  broad range of energy, spatial and temporal scales over which particle
  acceleration occurs in the solar atmosphere, in order to determine how
  and where energetic particles are accelerated. SPARK combines highly
  complementary imaging and spectroscopic observations of radiation from
  energetic electrons, protons and ions set in their plasma and magnetic
  context. The payload comprises focusing-optics X-ray imaging covering
  the range from 1 to 60 keV; indirect HXR imaging and spectroscopy
  from 5 to 200 keV, γ-ray spectroscopic imaging with high-resolution
  LaBr<SUB>3</SUB> scintillators, and photometry and source localisation
  at far-infrared wavelengths. The plasma environment of the regions
  of acceleration and interaction will be probed using soft X-ray
  imaging of the corona and vector magnetography of the photosphere
  and chromosphere. SPARK is designed for solar research. However,
  in addition it will be able to provide exciting new insights into the
  origin of particle acceleration in other regimes, including terrestrial
  gamma-ray flashes (TGF), the origin of γ-ray bursts, and the possible
  existence of axions.

---------------------------------------------------------
Title: Examining Rotational Variability in the Upper Tropospheres
    and Lower Stratospheres of Uranus and Neptune from Herschel PACS
OT1 Observations: Implications for the Stability of Temperature and
    Compositional Structure
Authors: Orton, G.; Feuchtgruber, H.; Fletcher, L.; Lellouch, E.;
   Moreno, R.; Billebaud, F.; Cavalie, T.; Decin, L.; Dobreijecvic, M.;
   Encrenaz, T.; Hartogh, P.; Jarchow, C.; Lara, L. M.; Liu, J.
2012EGUGA..14.3434O    Altcode:
  The power of high-resolution submillimeter spectroscopy of Uranus
  and Neptune was put to use to survey the rotational variability of
  stratospheric and tropospheric constituents of their atmospheres. These
  observations were motivated by the surprising discovery of as much as
  12% rotational variability of emission from stratospheric constituents
  in the atmosphere of Uranus by the Spitzer Infrared Spectrometer
  and the detection of spatial variability in thermal images of
  Neptune's stratospheric emission (Orton et al. 2007, Astron. &amp;
  Astrophys 473, L3). Our observing program consisted of three separate
  sequences of observations to look at the strongest lines of H2O in the
  high-resolution PACS spectra of both planets, whose upwelling radiance
  emerges from the same vertical region as the Spitzer IRS observations
  of Uranus and ground-based images of Neptune, and the strongest line
  of CH4 in the PACS spectrum of Neptune. We omitted measurements of
  CH4 lines in Uranus, which are almost non-detectable. We added the
  strongest HD line in Uranus to measure variability of tropospheric
  temperatures that could modulate stratospheric CH4 abundances through
  local cold-trapping and the strongest two HD lines in Neptune (Lellouch
  et al. 2010, Astron. &amp; Astrophys. 518, L152) that determine both
  the tropopause temperature to limit local cold-trapping efficacy and
  the lower stratospheric temperature, to help differentiate between
  longitudinal variability of stratospheric H2O and CH4 abundances
  vs. temperatures. These were repeated over the 17-hour interval that
  is common to the equatorial rotation periods of both Uranus and
  Neptune. Although these lines had already been observed in Uranus
  and Neptune by PACS, no repeat measurements had ever been made to
  determine longitudinal variability. The observations were consistent
  with previous measurements, but no significant rotational variability
  was detected. It is possible that the absence of rotational variability
  in the HD and CH4 lines is because variability is confined to very
  low pressures, e.g. much lower than a microbar. However, the absence
  of variable emission from high-altitude exogenic H2O vapor is harder
  to explain, unless the variability seen in Uranus by Spitzer and in
  Neptune from the VLT, is not the result of variations in temperature
  by in the hydrocarbon abundances. Alternatively, the stratospheres
  of both planets are variable in time. The cause of such variability
  is unknown, but spatially confined outbursts have been detected in
  the visible and near infrared, and they may have as much influence on
  the stratosphere of Uranus as the great springtime storm in Saturn's
  northern hemisphere, creating a strong, localized "beacon" of thermal
  radiation (cf. Fletcher et al. 2011, Science, 332,1413) that could
  dominate the emission observed over the hemisphere.

---------------------------------------------------------
Title: Observations of Enhanced Extreme Ultraviolet Continua during
    an X-Class Solar Flare Using SDO/EVE
Authors: Milligan, Ryan O.; Chamberlin, Phillip C.; Hudson, Hugh S.;
   Woods, Thomas N.; Mathioudakis, Mihalis; Fletcher, Lyndsay; Kowalski,
   Adam F.; Keenan, Francis P.
2012ApJ...748L..14M    Altcode: 2012arXiv1202.1731M
  Observations of extreme ultraviolet (EUV) emission from an X-class solar
  flare that occurred on 2011 February 15 at 01:44 UT are presented,
  obtained using the EUV Variability Experiment (EVE) on board the
  Solar Dynamics Observatory. The complete EVE spectral range covers
  the free-bound continua of H I (Lyman continuum), He I, and He II,
  with recombination edges at 91.2, 50.4, and 22.8 nm, respectively. By
  fitting the wavelength ranges blueward of each recombination edge
  with an exponential function, light curves of each of the integrated
  continua were generated over the course of the flare, as was emission
  from the free-free continuum (6.5-37 nm). The He II 30.4 nm and Lyα
  121.6 nm lines, and soft X-ray (SXR; 0.1-0.8 nm) emission from GOES are
  also included for comparison. Each free-bound continuum was found to
  have a rapid rise phase at the flare onset similar to that seen in the
  25-50 keV light curves from RHESSI, suggesting that they were formed
  by recombination with free electrons in the chromosphere. However,
  the free-free emission exhibited a slower rise phase seen also in the
  SXR emission from GOES, implying a predominantly coronal origin. By
  integrating over the entire flare the total energy emitted via
  each process was determined. We find that the flare energy in the
  EVE spectral range amounts to at most a few percent of the total
  flare energy, but EVE gives us a first comprehensive look at these
  diagnostically important continuum components.

---------------------------------------------------------
Title: Momentum Distribution in Solar Flare Processes
Authors: Hudson, H. S.; Fletcher, L.; Fisher, G. H.; Abbett, W. P.;
   Russell, A.
2012SoPh..277...77H    Altcode:
  We discuss the consequences of momentum conservation in processes
  related to solar flares and coronal mass ejections (CMEs), in particular
  describing the relative importance of vertical impulses that could
  contribute to the excitation of seismic waves ("sunquakes"). The
  initial impulse associated with the primary flare energy transport
  in the impulsive phase contains sufficient momentum, as do the
  impulses associated with the acceleration of the evaporation flow (the
  chromospheric shock) or the CME itself. We note that the deceleration
  of the evaporative flow, as coronal closed fields arrest it, will tend
  to produce an opposite impulse, reducing the energy coupling into
  the interior. The actual mechanism of the coupling remains unclear
  at present.

---------------------------------------------------------
Title: The role of filament activation in a solar eruption
Authors: Rubio da Costa, F.; Zuccarello, F.; Fletcher, L.; Romano,
   P.; Labrosse, N.
2012A&A...539A..27R    Altcode: 2014arXiv1412.1858R
  Context. Observations show that the mutual relationship between
  filament eruptions and solar flares cannot be described in terms of an
  unique scenario. In some cases, the eruption of a filament appears to
  trigger a flare, while in others the observations are more consistent
  with magnetic reconnection that produces both the flare observational
  signatures (e.g., ribbons, plasma jets, post-flare loops, etc.) and
  later the destabilization and eruption of a filament. <BR /> Aims:
  Contributing to a better comprehension of the role played by filament
  eruptions in solar flares, we study an event which occurred in NOAA
  8471, where a flare and the activation of (at least) two filaments
  were observed on 28 February 1999. <BR /> Methods: By using imaging
  data acquired in the 1216, 1600, 171 and 195 Å TRACE channels and by
  BBSO in the continnum and in the Hα line, a morphological study of
  the event is carried out. Moreover, using TRACE 1216 and 1600 Å data,
  an estimate of the "pure" Lyα power is obtained. The extrapolation of
  the magnetic field lines is done using the SOHO/MDI magnetograms and
  assuming a potential field. <BR /> Results: Initially an area hosting a
  filament located over a δ spot becomes brighter than the surroundings,
  both in the chromosphere and in the corona. This area increases in
  brightness and extension, eventually assuming a two-ribbon morphology,
  until it reaches the eastern part of the active region. Here a second
  filament becomes activated and the brightening propagates to the south,
  passing over a large supergranular cell. The potential magnetic field
  extrapolation indicates that the field line connectivity changes
  after the flare. <BR /> Conclusions: The event is triggered by the
  destabilization of a filament located between the two polarities
  of a δ spot. This destabilization involves the magnetic arcades
  of the active region and causes the eruption of a second filament,
  that gives rise to a CME and to plasma motions over a supergranular
  cell. We conclude that in this event the two filaments play an active
  and decisive role, albeit in different stages of the phenomenon,
  in fact the destabilization of one filament causes brightenings,
  reconnection and ribbons, while the second one, whose eruption is caused
  by the field reconfiguration resulting from the previous reconnection,
  undergoes the greatest changes and causes the CME.

---------------------------------------------------------
Title: JUpiter ICy moons Explorer (JUICE): An ESA L-Class Mission
    Candidate to the Jupiter System
Authors: Dougherty, M.; Grasset, O.; Erd, C.; Titov, D.; Bunce,
   E.; Coustenis, A.; Blanc, M.; Coates, A.; Drossart, P.; Fletcher,
   L.; Hussmann, H.; Jaumann, R.; Krupp, N.; Prieto-Ballesteros, O.;
   Tortora, P.; Tosi, F.; van Hoolst, T.
2012LPI....43.1806D    Altcode:
  JUICE is the next step for an in-depth exploration of the geophysical
  and environmental characteristics of Ganymede and exploration of
  Callisto and Europa, and will provide an in-depth understanding of
  Jupiter’s atmosphere and magnetosphere.

---------------------------------------------------------
Title: Further seasonal changes in Uranus’ cloud structure observed
    by Gemini-North and UKIRT
Authors: Irwin, P. G. J.; Teanby, N. A.; Davis, G. R.; Fletcher,
   L. N.; Orton, G. S.; Calcutt, S. B.; Tice, D. S.; Hurley, J.
2012Icar..218...47I    Altcode:
  Near-infrared observations of Uranus were made in October/November 2010
  with the Gemini-North telescope in Hawaii, using NIFS, an integral field
  spectrograph, and the NIRI instrument in imaging mode. Observations
  were acquired using adaptive optics and have a spatial resolution of
  approximately 0.1-0.2″. <P />The observed spectra along Uranus’
  central meridian were analysed using a multiple-scattering retrieval
  algorithm to infer the vertical/latitudinal variation in cloud
  optical depth, which we compare with previous observations made by
  Gemini-North/NIFS in 2009 and UKIRT/UIST observations made between 2006
  and 2008. Assuming a continuous distribution of small particles (r ∼
  1 μm, and refractive index of 1.4 + 0i) with the single scattering
  albedo set to 0.75 and using a Henyey-Greenstein phase function with
  asymmetry parameter set to 0.7 at all wavelengths and latitudes, the
  retrieved cloud density profiles show that the north polar zone at
  45°N has continued to steadily brighten while the south polar zone at
  45°S has continued to fade. As with our previous analyses we find that,
  assuming that the methane vertical profile is the same at all latitudes,
  the clouds forming these polar zones at 45°N and 45°S lie at slightly
  lower pressures than the clouds at more equatorial latitudes. However,
  we also find that the Gemini data can be reproduced by assuming that
  the main cloud remains fixed at ∼2 bar at all latitudes and adjusting
  the relative humidity of methane instead. In this case we find that
  the deep cloud is still more opaque at the equator and at the zones at
  45°N and 45°S and shows the same seasonal trends as when the methane
  humidity remain fixed. However, with this approach the relative humidity
  of methane is seen to rise sharply from approximately 20% at polar
  latitudes to values closer to 80% for latitudes equatorward of 45°S
  and 45°N, consistent with the analysis of 2002 HST observations by
  Karkoschka and Tomasko (Karkoschka, E., Tomasko, M. [2009]. Icarus 202,
  287-302), with a possible indication of seasonal variability. Overall,
  Uranus appeared to be less convectively active in 2010 than in the
  previous 4 years, supporting the conclusion that now the northern
  spring equinox (which occurred in 2007) has passed, the atmosphere is
  settling back into the more quiescent state seen by Voyager 2 in 1986.

---------------------------------------------------------
Title: Sub-millimetre spectroscopy of Saturn's trace gases from
    Herschel/SPIRE
Authors: Fletcher, L. N.; Swinyard, B.; Salji, C.; Polehampton, E.;
   Fulton, T.; Sidher, S.; Lellouch, E.; Moreno, R.; Orton, G.; Cavalié,
   T.; Courtin, R.; Rengel, M.; Sagawa, H.; Davis, G. R.; Hartogh, P.;
   Naylor, D.; Walker, H.; Lim, T.
2012A&A...539A..44F    Altcode:
  <BR /> Aims: We provide an extensive new sub-millimetre survey of
  the trace gas composition of Saturn's atmosphere using the broad
  spectral range (15-51 cm<SUP>-1</SUP>) and high spectral resolution
  (0.048 cm<SUP>-1</SUP>) offered by Fourier transform spectroscopy
  by the Herschel/SPIRE instrument (Spectral and Photometric Imaging
  REceiver). Observations were acquired in June 2010, shortly after
  equinox, with negligible contribution from Saturn's ring emission. <BR
  /> Methods: Tropospheric temperatures and the vertical distributions
  of phosphine and ammonia are derived using an optimal estimation
  retrieval algorithm to reproduce the sub-millimetre data. The abundance
  of methane, water and upper limits on a range of different species are
  estimated using a line-by-line forward model. <BR /> Results: Saturn's
  disc-averaged temperature profile is found to be quasi-isothermal
  between 60 and 300 mbar, with uncertainties of 7 K due to the absolute
  calibration of SPIRE. Modelling of PH<SUB>3</SUB> rotational lines
  confirms the vertical profile derived in previous studies and shows
  that negligible PH<SUB>3</SUB> is present above the 10- to 20-mbar
  level. The upper tropospheric abundance of NH<SUB>3</SUB> appears
  to follow a vapour pressure distribution throughout the region of
  sensitivity in the SPIRE data, but the degree of saturation is highly
  uncertain. The tropospheric CH<SUB>4</SUB> abundance and Saturn's bulk
  C/H ratio are consistent with Cassini studies. We improve the upper
  limits on several species (H<SUB>2</SUB>S, HCN, HCP and HI); provide
  the first observational constraints on others (SO<SUB>2</SUB>, CS,
  methanol, formaldehyde, CH<SUB>3</SUB>Cl); and confirm previous upper
  limits on HF, HCl and HBr. Stratospheric emission from H<SUB>2</SUB>O
  is suggested at 36.6 and 38.8 cm<SUP>-1</SUP> with a 1σ significance
  level, and these lines are used to derive mole fractions and column
  abundances consistent with ISO and SWAS estimations a decade earlier.

---------------------------------------------------------
Title: Optimal estimation retrievals of the atmospheric structure
    and composition of HD 189733b from secondary eclipse spectroscopy
Authors: Lee, J. -M.; Fletcher, L. N.; Irwin, P. G. J.
2012MNRAS.420..170L    Altcode: 2011arXiv1110.2934L; 2011MNRAS.tmp.1983L
  Recent spectroscopic observations of transiting hot Jupiters have
  permitted the derivation of the thermal structure and molecular
  abundances of H<SUB>2</SUB>O, CO<SUB>2</SUB>, CO and CH<SUB>4</SUB>
  in these extreme atmospheres. Here, for the first time, we apply the
  technique of optimal estimation to determine the thermal structure
  and composition of an exoplanet by solving the inverse problem. The
  development of a suite of radiative transfer and retrieval tools
  for exoplanet atmospheres is described, building upon a retrieval
  algorithm which is extensively used in the study of our own Solar
  system. First, we discuss the plausibility of detection of different
  molecules in the dayside atmosphere of HD 189733b and the best-fitting
  spectrum retrieved from all publicly available sets of secondary
  eclipse observations between 1.45 and 24 μm. Additionally, we use
  contribution functions to assess the vertical sensitivity of the
  emission spectrum to temperatures and molecular composition. Over
  the altitudes probed by the contribution functions, the retrieved
  thermal structure shows an isothermal upper atmosphere overlying a
  deeper adiabatic layer (temperature decreasing with altitude), which
  is consistent with previously reported dynamical and observational
  results. The formal uncertainties on retrieved parameters are estimated
  conservatively using an analysis of the cross-correlation functions and
  the degeneracy between different atmospheric properties. The formal
  solution of the inverse problem suggests that the uncertainties on
  retrieved parameters are larger than suggested in previous studies,
  and that the presence of CO and CH<SUB>4</SUB> is only marginally
  supported by the available data. Nevertheless, by including as broad
  a wavelength range as possible in the retrieval, we demonstrate that
  available spectra of HD 189733b can constrain a family of potential
  solutions for the atmospheric structure.

---------------------------------------------------------
Title: Retrieval of Atmosphere Structure and Composition of Exoplanets
    from Transit Spectroscopy
Authors: Lee, Jae-Min; Fletcher, L. N.; Irwin, P. G. J.
2012AAS...21940502L    Altcode:
  Recent spectroscopic observations of transiting exoplanets of HD
  189733b, HD 209458b, GJ 436b and GJ 1214b provide the best chance
  of characterizing the thermal structure and composition of their
  atmospheres. Here we have applied an optimal estimation retrieval
  architecture to fit exoplanet spectra to determine the thermal
  structure and composition by solving the inverse problem. The
  development of a suite of radiative transfer and retrieval tools for
  exoplanet atmospheres is explained, building upon a rapid correlated-k
  approximation and a retrieval algorithm extensively used in our own
  solar system. With these tools we discuss the best-fitting spectrum to
  the measurements with the best-estimated solution (i.e. the maximum
  a posteriori solution) for the vertical temperature structure and
  molecular abundances. Additionally, the contribution functions and
  the vertical sensitivity to the molecules are fully utilized to
  interpret transmission and emission spectra, probing the structure
  and composition of the atmosphere. Furthermore, the analysis of the
  cross-correlation functions permits us to quantify the uncertainties
  in the degeneracy between the retrieved atmospheric properties based
  on the current quality of the data. This sheds light on the range
  of diverse interpretations offered by other studies so far. It also
  allows us to scrutinize further atmospheric features by maximizing
  the capability of the current retrieval algorithm and to demonstrate
  the benefit of using as broad a spectral range as possible, with clear
  implications for the next generation of exoplanetary missions.

---------------------------------------------------------
Title: Relationship between an M6.6 solar flare and subsequent
    filament activations.
Authors: Rubio da Costa, F.; Zuccarello, F.; Romano, P.; Fletcher,
   L.; Labrosse, N.
2012MSAIS..19..113R    Altcode:
  We study an event which occurred in NOAA 8471, where an M6.6 flare
  and the activation of two filaments were observed on 28 February
  1999. A multi-wavelength study allows us to investigate the behavior
  of the several features observed at different atmospheric levels, that
  might be used to answer to the question whether and in what conditions
  the eruption of filaments can play an active or a passive role in the
  flare occurrence. Imaging data were acquired by BBSO in the Halpha line
  and by TRACE in the 1216, 1600, 171 and 195 Å channels, allowing us
  to deduce the morphology and temporal evolution of the event and to
  estimate the Ly-alpha power. Moreover, in order to study the magnetic
  topology, the extrapolation of the photospheric magnetic field lines
  was done assuming potential field and using SOHO/MDI magnetograms.

---------------------------------------------------------
Title: Solar flares in Halpha  and Ly-alpha : observations vs
    simulations.
Authors: Rubio da Costa, F.; Zuccarello, F.; Fletcher, L.; Labrosse,
   N.; Prosecký, T.; Kašparová, J.
2012MSAIS..19..117R    Altcode:
  In order to study the properties of faint, moderate and bright flares,
  we simulate the conditions of the solar atmosphere using a radiative
  hydrodynamic model \citep{2005ApJ...630..573A}. A constant beam of
  non-thermal electrons is injected at the apex of a 1D coronal loop
  and heating from thermal soft X-ray and UV emission is included. We
  study the contribution of different processes to the total intensity of
  different lines at different atmospheric layers. We obtain the total
  integrated intensity of different lines and we compare those of the
  Ly-alpha and Halpha lines with the observational values for Ly-alpha
  (using TRACE 1216 and 1600 Å data and estimating the “pure” Ly-alpha
  emission) and Halpha (using data from the Ondřejov Observatory). We
  inferred from the analysis of the values obtained by simulation that
  the X-ray energy of the different kind of flares does not strongly
  affect the Ly-alpha results; the Halpha results are comparable to the
  observed ones, concluding that the simulated solar atmosphere fits
  better at lower layers of the chromosphere than at upper layers.

---------------------------------------------------------
Title: Saturn's Great White Storm (2010): Correlations between Clouds
    and Thermal Fields?
Authors: Momary, T.; Yanamandra-Fisher, P. A.; Orton, G. S.; Baines,
   K. H.; Fletcher, L.; Trinh, S.; Delcroix, M.
2011AGUFM.P13C1683M    Altcode:
  It is well known that convective storms occur regularly in Saturn's
  atmosphere, but giant storm outbreaks, known as Great White Spot
  (GWS) outbreaks, occur approximately every 29 years or once per
  Saturnian year, just past northern solstice. Including the recent
  GWS outbreak of December 2010, a total of six have occurred, and are
  considered to be related to the changing seasonal insolation, though
  their triggers are not yet known or what occurs below the clouds on
  smaller temporal and spatial timelines. Although not predictable, as
  evidenced by the current Northern Storm and observed by Cassini, the
  great storms start out with a violent outbreak, dredging up material
  from the deep atmosphere, which then is dispersed by the prevailing
  winds. The recent 2010 December GWS outbreak is an outlier, occurring
  at northern latitudes of approximately 35°N (the northern "Tornado
  Alley"), just past vernal equinox, almost a season early. It has rapidly
  encircled the planet in two months and is now in its mature phase, with
  discrete structure obvious at all longitudes at both mid-infrared and
  deep atmosphere (or 5-microns). Recent amateur observations indicate a
  link between lightning strikes, convective storm activity, GWS and spoke
  activity in the morning ansa (Delacroix et al., 2011). We shall explore
  correlations between the many visible/CCD observations from the amateur
  community, the albedo and thermal maps produced with data acquired from
  NASA/InfraRed Telescope Facility (IRTF)/NSFCAM2, a 1 - 5-micron imager,
  during the various phases of the 2010 - 2011 GWS. We will characterize
  changes in the local environs of the outbreak site at various epochs and
  compare with other locations on the planet. Delacroix, M., E. Kraaikamp
  and P. Yanamandra-Fisher,2011. First Ground Observations of Saturn's
  Spokes Around 2009 Equinox. EPSC/DPS, Nantes, France.

---------------------------------------------------------
Title: A Sensitive Search for Traces of Stratospheric NH3, PH3,
    C2H5D, and CH2C2H2 within Saturn's Beacon
Authors: Greathouse, T. K.; Irons, W.; Fouchet, T.; Fletcher, L.;
   Orton, G. S.; Bézard, B.; Tokunaga, A. T.; Lacy, J. H.
2011AGUFM.P13C1682G    Altcode:
  The development of a hot region in Saturn's stratosphere, the
  Beacon, coincided with observations of a massive storm outbreak in
  Saturn's deeper atmosphere. It is thought that these disturbances
  in the troposphere and stratosphere are related. The severity
  and size of the deep convective storm along with the increased
  stratospheric temperatures of the Beacon suggested the possibility
  that the tropospheric convection was strong enough to inject chemical
  constituents from the troposphere into the stratosphere by convective
  overshoot. Using the high spectral resolution capabilities of TEXES,
  the Texas Echelon cross Echelle Spectrograph, mounted on the NASA
  Infrared Telescope Facility, IRTF, we performed a sensitive search for
  NH3 and PH3 emission lines that would indicate the presence of NH3 and
  PH3 in the stratospheric region of the Beacon. We will present upper
  limits to the NH3 and PH3 abundances as initial reductions of the data
  retrieved between July 14th and 19th, 2011 showed no obvious emission
  features from either gas. The high temperatures within the Beacon
  also allowed for a detailed search for molecules as yet undetected in
  the stratospheres of the Outer Planets, but predicted to exist at low
  abundance levels. Observations centered at 800 cm-1 and 845 cm-1 were
  retrieved to search for C2H5D and CH2C2H2 emission, respectively. Like
  the search for NH3 and PH3, initial reductions show no trace of these
  molecules. We will present a more thorough analysis with an upper
  limit to the CH2C2H2 abundance within the Beacon. Only a model to data
  comparison will be made for the C2H5D spectral setting, since a full
  set of line parameters for this molecule have yet to be recorded.

---------------------------------------------------------
Title: High Energy Solar Physics Data in Europe (HESPE): a European
    project for the exploitation of hard X-ray data in solar flare physics
Authors: Piana, M.; Csillaghy, A.; Kontar, E. P.; Fletcher, L.;
   Veronig, A. M.; Vilmer, N.; Hurford, G. J.; Dennis, B. R.; Schwartz,
   R. A.; Massone, A.; Krucker, S.; Benvenuto, F.; Etesi, L. I.; Guo,
   J.; Hochmuth, N.; Reid, H.
2011AGUFMSH33B2068P    Altcode:
  It has been recognized since the early days of the space program that
  high-energy observations play a crucial role in understanding the basic
  mechanisms of solar eruptions. Unfortunately, the peculiar nature of
  this radiation makes it so difficult to extract useful information
  from it that non-conventional observational techniques together with
  complex data analysis procedures must be adopted. HESPE is a European
  project funded within the seventh Framework Program, with the aim of
  realizing computational methods for solar high-energy data analysis and
  technological tools for the intelligent exploitation of science-ready
  products. Such products and methods are put at disposal of the solar,
  heliospheric and space weather communities, who will exploit them in
  order to build flare prediction models and to integrate the information
  extracted from hard X-rays and gamma rays data, with the one extracted
  from other wavelengths data.

---------------------------------------------------------
Title: Non-Observation of the He II 304 A Charge-Exchange Continuum
    in Major Solar Flares
Authors: Hudson, H. S.; Fletcher, L.; MacKinnon, A.; Woods, T. N.
2011AGUFMSH41A1909H    Altcode:
  We report on a search for flare emission via charge-exchange continuum
  radiation in the wings of the Lyman-alpha line of He ii at 304 A, as
  originally suggested for hydrogen by Orrall and Zirker (1976). Via this
  mechanism a primary alpha particle that penetrates into the neutral
  chromosphere can pick up an atomic electron and radiate recombination
  continuum before it stops. The Extreme-ultraviolet Variability
  Experiment (EVE) on board the Solar Dynamics Observatory (SDO) gives
  us our first chance to search for this effect systematically. The
  Orrall-Zirker charge-exchange mechanism has great importance for flare
  physics because of the essential roles that particle acceleration plays;
  this mechanism is one of the few proposed that would allow remote
  sensing of primary accelerated particles below a few MeV/nucleon. We
  study four EVE events: the gamma-ray events SOL2010-06-12 (M2.0) and
  SOL20 11-02-24 (M3.5), the latter a limb flare, and the X-class flares
  SOL2010-02-15 (X2.2) and SOL2011-03-09 (X1.2). No clear signature of
  the charge-exchange continuum appears, but SOL2010-02-15 (X2.2) does
  reveal a gradual broad-band signature that we tentatively interpret
  as due to unresolved emission lines or instrumental scattering.

---------------------------------------------------------
Title: Splinter Session "Solar and Stellar Flares"
Authors: Fletcher, L.; Hudson, H.; Cauzzi, G.; Getman, K. V.; Giampapa,
   M.; Hawley, S. L.; Heinzel, P.; Johnstone, C.; Kowalski, A. F.; Osten,
   R. A.; Pye, J.
2011ASPC..448..441F    Altcode: 2011csss...16..441F; 2012arXiv1206.3997F
  This summary reports on papers presented at the Cool Stars-16 meeting in
  the splinter session "Solar and Stellar flares." Although many topics
  were discussed, the main themes were the commonality of interests,
  and of physics, between the solar and stellar flare communities,
  and the opportunities for important new observations in the near future.

---------------------------------------------------------
Title: Investigation of the Photochemistry in Saturn's Ring Shadowed
Atmosphere: Production Rates of Key Atmospheric Molecules
Authors: Edgington, S. G.; Atreya, S. K.; Wilson, E. H.; Baines,
   K. H.; West, R. A.; Bjoraker, G. L.; Fletcher, L.
2011AGUFM.P13C1685E    Altcode:
  Cassini has been orbiting Saturn for well over seven years. During
  this epoch, the ring shadow has changed from shading a large portion
  of the northern hemisphere to shading a small region just south of the
  equator and is continuing southward. At Saturn Orbit Insertion (July
  1, 2004), the ring plane was inclined by ~24 degrees relative to the
  Sun-Saturn vector. The projection of the B-ring onto Saturn reached as
  far as 40N along the central meridian (~52N at the terminator). At its
  maximum extent, the ring shadow can reach as far as 48N (~58N at the
  terminator). The net result, is that the intensity of both ultraviolet
  and visible sunlight penetrating into any particular northern/southern
  latitude will vary depending on Saturn's tilt relative to the Sun
  and the optical thickness of each ring system. Previous work [1]
  looked at the variation of the solar flux as a function of solar
  inclination, i.e. season (see Figure 1). The current work looks at
  the impact of the oscillating ring shadow on the photodissociation
  and production rates of key molecules in Saturn's stratosphere and
  upper troposphere over time. Beginning with methane, the impact on
  production and loss rates of the long-lived photochemical hydrocarbons
  leading to haze formation are examined at several latitudes over a
  Saturn year. We also look at the impacts on phosphine abundance, a
  disequilibrium species whose presence in the upper troposphere is a
  tracer of convection processes in the deep atmosphere. Comparison to
  the corresponding photodissociation rates for a clear atmosphere and
  the effect of dynamical mixing will be presented. [1] Edgington,S.G.,
  et al., 2006. Adaptation of a 2-D Photochemical Model to Improve Our
  Understanding of Saturn's Atmosphere. B.A.A.S., 38, 499 (#11.23). The
  research described in this paper was carried out at the Jet Propulsion
  Laboratory, California Institute of Technology, under a contract with
  the National Aeronautics and Space Administration.

---------------------------------------------------------
Title: The Evolution of Trace Species and Temperature in Saturn's
    Northern Storm Region
Authors: Hesman, B. E.; Fletcher, L.; Bjoraker, G. L.; Sada, P. V.;
   Achterberg, R. K.; Jennings, D. E.; Lunsford, A. W.; Boyle, R. J.;
   Kerr, T.; Romani, P. N.; Simon-Miller, A. A.; Nixon, C. A.; Davis,
   G. R.; Irwin, P. G.
2011AGUFM.P11H..04H    Altcode:
  The massive eruption at 40°N (planetographic latitude) in December
  2010 has produced significant and long-lived changes in temperature and
  species abundances in Saturn's northern hemisphere (Fletcher et al.,
  2011). The northern storm region has been observed on many occasions
  in between January and August of 2011 by Cassini's Composite Infrared
  Spectrometer (CIRS). In this time period, temperatures in regions
  referred to as "beacons" (warm regions in the stratosphere at certain
  longitudes in the storm latitude) became significantly warmer than
  pre-storm values of 140K. These temperatures reached a peak of 220K near
  the 2-mbar region in May 2011 following the merger of two beacons. These
  are the highest temperatures ever observed at this altitude on
  Saturn. The temperatures in the storm region vary longitudinally
  by ~70K which is the largest variation in temperature ever seen on
  Saturn. These warm temperatures resulted in the detection of ethylene
  (C<SUB>2</SUB>H<SUB>4</SUB>) using CIRS. Early analysis of the May
  data indicates ethylene volume mixing ratios of 3x10<SUP>-8</SUP>
  at 2 mbar. These beacon regions have also led to the identification
  of rare species such as diacetylene (C<SUB>4</SUB>H<SUB>2</SUB>),
  methylacetylene (CH<SUB>3</SUB>C<SUB>2</SUB>H), and carbon dioxide
  (CO<SUB>2</SUB>) in the stratosphere. These species were previously
  measured by the Infrared Space Observatory (de Graauw et al.,
  1997) and CIRS (Guerlet et al., 2010). However, mapping these
  species in longitude and latitude over the storm region using CIRS
  provides insight into the changes in the photochemistry induced
  by the storm. Ground-based observations were performed using the
  high-resolution spectrometer Celeste in May and July to confirm the
  CIRS detection of ethylene and to study its spectral signatures at
  higher spectral resolution than available with CIRS, and investigate
  the evolution of its abundance profile as the storm progresses. The
  time evolution of ethylene abundance in Saturn's northern storm region
  using CIRS and ground-based data from the McMath-Pierce Telescope
  (May 2011) and the United Kingdom Infrared Telescope (July 2011)
  will be presented. In addition, the abundance profiles, as measured
  by CIRS, of C<SUB>4</SUB>H<SUB>2</SUB>, CH<SUB>3</SUB>C<SUB>2</SUB>H,
  and CO<SUB>2</SUB> will also be discussed including how their abundance
  profiles have changed throughout the storm period.

---------------------------------------------------------
Title: TEXES observations of Saturn's stratospheric thermal structure
    after the 2010 convective event
Authors: Fouchet, T.; Greathouse, T. K.; Fletcher, L. N.; Richter,
   M. J.; Lacy, J. H.; Irons, W.; Guerlet, S.; Bézard, B.; Lellouch,
   E.; Hesman, B. E.; Achterberg, R. K.; Tokunaga, A. T.
2011AGUFM.P13C1681F    Altcode:
  In December 2010, a huge convective event distorted the cloud layer
  at 40 N in Saturn's springtime hemisphere. These large convective
  events are observed regularly in Saturn's atmosphere, about one event
  per saturnian year, and may play a central role in the transport of
  the internal heat flux to the radiative layer. However, this event
  occured at a season (Ls=16) different from that of the previous
  events (Ls= 110-170). Another unexpected aspect of the 2010 event
  was its stratospheric signature. As shown by Fletcher et al. (2011)
  from Cassini/CIRS and VLT/VISIR, in the 40N latitude band, the 1-mbar
  pressure level warmed by several tens of K at some longitudes and
  cooled by several K at other longitudes. In order to assess the vertical
  thermal structure in the disturbed latitudinal band, we performed five
  half-nights of observations with TEXES mounted on the NASA Infrared
  Telescope Facility (IRTF) from July 14th, 2011 to July 19th, 2011. The
  high spectral resolution (R=100,000) provided by TEXES allowed us to
  resolve several lines of methane in the range 1245-1250 cm-1, and the
  H<SUB>2</SUB> S(1) quadrupole line and collision-induced continuum to
  measure the temperature structure between 100~mbar and 0.01~mbar. We
  will present the results of the observations in terms of stratospheric
  temperature structure.

---------------------------------------------------------
Title: Cassini/CIRS Observations of Temperatures in Saturn's Northern
    Storm Region
Authors: Achterberg, R. K.; Hesman, B. E.; Bjoraker, G. L.; Fletcher,
   L.; Conrath, B. J.; Gierasch, P. J.; Flasar, F. M.
2011AGUFM.P13C1680A    Altcode:
  In early December 2010, a large convective storm appeared in Saturn's
  northern hemisphere, centered near 40°N planetographic at the center of
  a westward jet (Sanchez-Lavega et al., 2011; Fisher et al. 2011). Storms
  of the observed magnitude, referred to as Great White Spots (GWS),
  are rare on Saturn, historically occurring once per Saturn year (30
  Earth years), at equatorial or mid-northern latitudes during northern
  summer; the current storm is unusual in occurring during northern
  spring, roughly one season earlier than previous GWS outbursts. Thermal
  infrared observations, both groundbased and from the Cassini Composite
  Infrared Spectrometer (CIRS) orbiting Saturn, taken six weeks after the
  appearance of the storm, revealed significant changes to the thermal
  structure of Saturn's northern hemisphere (Fletcher et al., 2011). Cold
  temperatures were measured at the location of the disturbance in both
  the upper troposphere and stratosphere, and, surprisingly, hot spots
  to the east and west of the disturbance longitude with temperature
  contrasts of 16K, much larger than usual zonal temperature contrasts
  on Saturn. CIRS has continued to observe the latitude of the storm
  at one to two month intervals. These observations typically cover an
  approximately 10° wide latitude strip over one or two rotations of
  Saturn at a spatial resolution of 2° of arc in the CIRS mid-IR focal
  planes (600-1400 cm<SUP>-1</SUP>, 7-16μm). From these observations,
  we can retrieve temperatures in the upper troposphere between 50
  and 200 mbar, and in the middle stratosphere between ~0.2 and 10
  mbar. These observations show that temperatures in the stratospheric
  hot spots continued to increase through May 2011, when temperatures
  reached a peak of over 220 K, following the merger of two hot spots
  into one, with zonal temperature contrasts of 70 K. By mid-July,
  the maximum temperature in the hot spot had decreased to just under
  200K. Furthermore, in May and July, the peak temperatures were at a
  pressure roughly two scale heights larger (lower in altitude) than
  in earlier observations - 2 mbar compared to 0.4 mbar. In the upper
  troposphere, temperature perturbations associated with the storm are
  around 5 to 10 K, larger than seen on Saturn prior to the storm, but
  much smaller than the temperature variations seen in the stratosphere.

---------------------------------------------------------
Title: Thermal Evolution of Saturn's 2010-2011 Disturbance
Authors: Orton, G. S.; Fletcher, L.; Yanamandra-Fisher, P.; Mason,
   C.; Greco, J.; Valkov, S.; Baines, K. H.; Nanu, R.; Villar, G.; Trinh,
   S.; Pacheco, J.; Sola, M.; Momary, T.; Greathouse, T. K.; Fouchet, T.
2011AGUFM.P13C1679O    Altcode:
  The remarkable disturbance that began in Saturn's northern hemisphere
  late in 2010 was initiated by a single discrete outburst of bright
  white cloud material, which spread with the prevailing zonal winds
  to completely encircle the planet within a matter of weeks. We report
  here the results of studies of the influence of the storm on thermal
  emission. These were obtained from thermal imaging observations
  between 5 and 25 μm, combining high-resolution imaging from ESO's
  Very Large Telescope (VLT) using the VISIR instrument and more
  frequent imaging from NASA's Infrared Telescope Facility (IRTF) using
  the MIRSI and NSFCam2 instruments. These observations were used to
  document the evolution of the spatial distributions of temperatures,
  gas composition and cloud opacity to trace the atmospheric circulation
  associated with the storm, which is consistent with a single convective
  plume in the deep clouds, sheared by the zonal winds and triggering
  widespread planetary wave activity. The disturbance generated the
  largest stratospheric thermal anomalies ever detected on Saturn
  (infrared 'beacons' that dominate the planetary emission), revealing
  dynamical coupling over hundreds of kilometers from the troposphere
  to the stratosphere. Observations made between January and March of
  2011 revealed the presence of two stratospheric 'beacons' and only
  tropospheric cooling associated with the upwelling regions of the
  disturbance. Observations in April and thereafter showed that these
  'beacons' had merged into a single feature, and that temperatures
  in the upper troposphere were increasing with time around the
  disturbance. Coincident with the disturbance, there appeared a major
  increase in the amplitude of zonal thermal waves in the northern
  hemisphere at longitudes distant from the disturbance. We note that
  the amplitude of zonal thermal waves in the southern hemisphere also
  increased. We will continue to track the evolution of this phenomenon,
  providing support for ground-based and Cassini spectroscopic
  observations.

---------------------------------------------------------
Title: The Evolution of Saturn's Northern Storm of 2010-2011 and
    Environs as Viewed by Cassini/VIMS
Authors: Baines, K. H.; Momary, T.; Fletcher, L.; Showman, A. P.;
   Delitsky, M.; Brown, R. H.; Buratti, B. J.; Clark, R. N.; Nicholson,
   P. D.; Sotin, C.
2011AGUFM.P11H..06B    Altcode:
  Images and spectra acquired by the Visual Infrared Mapping Spectrometer
  on board the Cassini Orbiter reveal that the current northern storm
  on Saturn is remarkable for (1) its location - the first significant
  storm seen in northern mid-latitudes since 1906, (2) its duration -
  presently approaching 8 months, and (3) its power, as indicated by
  the relatively massive ammonia-laden clouds it produces that reveal
  significant, persistent transport of materials over at least one
  bar of depth (&gt; 30 km of altitude). Situated near 35 degrees
  north latitude (planetocentric) near the maximum of a westward jet,
  the storm head moves westward at ~ 2.7 degrees per day, or ~ 27
  m/s. Multi-spectral images of the feature and its environs in 352 colors
  spanning nearly all longitudes were acquired by VIMS on February 24,
  May 11 and July 12, 2011. In all imagery, the head of the storm appears
  atypically dark in ammonia-ice sensitive wavelengths 2.73-3.1 micron,
  indicating significant amounts of ammonia ice. Simultaneously, the
  feature appears bright at pseudo-continuum near-infrared wavelengths,
  particularly at 4.08 micron, indicating an atypically massive cloud of
  large particles. Some 3-5 degree of latitude to the north and south of
  the cloudhead, streamers of such large-particle ammonia clouds extend
  more than 150 degrees of longitude to the east. While these streamers
  appear nearly equivalent in brightness in diagnostic wavelengths in
  the February 24, 2011 observations, the northern streamer clearly
  dominates in the May 11, 2011 map. As well, a new dark spot, the first
  observed associated with this storm, appears more than 250 degrees
  of longitude downstream of the cloudhead in the May 11, 2011 images
  and persists through the July 12, 2011 observations. Its appearance
  may be associated with the dissipation of overlying cloud features as
  the dark spot wandered eastward, Similar in size (&gt; 3000 km) and
  spectral appearance to the dark spots associated with the 2008 southern
  storm (Baines et al, Planetary and Space Sci., 57, 1650-1658,2009),
  this feature suggests upwelling of materials from the ~10-bar level,
  as previously proposed for the southern storm. New imagery expected in
  August 2011 as well as additional analysis of the July, 2011 images will
  be discussed and dynamical implications presented, including possible
  relationships of the northern storm with the String of Pearls feature
  observed for 5 years in the same latitude and longitude range but which
  has not been observed since the advent of the storm in December 2010.

---------------------------------------------------------
Title: Multispectral imaging observations of Neptune's cloud structure
    with Gemini-North
Authors: Irwin, P. G. J.; Teanby, N. A.; Davis, G. R.; Fletcher,
   L. N.; Orton, G. S.; Tice, D.; Hurley, J.; Calcutt, S. B.
2011Icar..216..141I    Altcode:
  Observations of Neptune were made in September 2009 with the
  Gemini-North Telescope in Hawaii, using the NIFS instrument in the
  H-band covering the wavelength range 1.477-1.803 μm. Observations
  were acquired in adaptive optics mode and have a spatial resolution
  of approximately 0.15-0.25″. The observations were analysed with a
  multiple-scattering retrieval algorithm to determine the opacity of
  clouds at different levels in Neptune's atmosphere. We find that the
  observed spectra at all locations are very well fit with a model that
  has two thin cloud layers, one at a pressure level of ∼2 bar all over
  the planet and an upper cloud whose pressure level varies from 0.02 to
  0.08 bar in the bright mid-latitude region at 20-40°S to as deep as 0.2
  bar near the equator. The opacity of the upper cloud is found to vary
  greatly with position, but the opacity of the lower cloud deck appears
  remarkably uniform, except for localised bright spots near 60°S and a
  possible slight clearing near the equator. A limb-darkening analysis of
  the observations suggests that the single-scattering albedo of the upper
  cloud particles varies from ∼0.4 in regions of low overall albedo
  to close to 1.0 in bright regions, while the lower cloud is consistent
  with particles that have a single-scattering albedo of ∼0.75 at this
  wavelength, similar to the value determined for the main cloud deck in
  Uranus' atmosphere. The Henyey-Greenstein scattering particle asymmetry
  of particles in the upper cloud deck are found to be in the range g
  ∼ 0.6-0.7 (i.e. reasonably strongly forward scattering). Numerous
  bright clouds are seen near Neptune's south pole at a range of pressure
  levels and at latitudes between 60 and 70°S. Discrete clouds were seen
  at the pressure level of the main cloud deck (∼2 bar) at 60°S on
  three of the six nights observed. Assuming they are the same feature
  we estimate the rotation rate at this latitude and pressure to be 13.2
  ± 0.1 h. However, the observations are not entirely consistent with
  a single non-evolving cloud feature, which suggests that the cloud
  opacity or albedo may vary very rapidly at this level at a rate not
  seen in any other giant-planet atmosphere.

---------------------------------------------------------
Title: Thermal Evolution of Saturn's Springtime Disturbance
Authors: Fletcher, L. N.; Orton, G. S.; Irwin, P. G. J.;
   Sanchez-Lavega, A.; Baines, K. H.; Hesman, B. E.; Read, P. L.; Flasar,
   F. M.; Momary, T. W.; Simon-Miller, A. A.; Hueso, R.; Bjoraker, G. L.;
   Yanamandra-Fisher, P.
2011epsc.conf..713F    Altcode: 2011DPS....43..713F
  Saturn's slow seasonal warming was spectacularly disrupted in
  December 2010 by the eruption of an enormous storm system in its
  springtime hemisphere. This storm, which is still evolving at the
  time of writing, is only the sixth known example of a planetwide
  storm system on Saturn, and the first to occur at this latitude
  (near 40oN) in over a century [1,2]. A combined analysis of thermal
  infrared imaging from ESO's Very Large Telescope VISIR instrument and
  5-200 μm spectroscopy from instruments onboard Cassini revealed the
  substantial atmospheric perturbations related to the storm complex over
  a wide range of altitudes [1]. Since that time the storm complex has
  continued to evolve through the mature phase. In particular Saturn's
  newly-identified stratospheric beacons (a high-altitude response to
  mechanical forcing from the troposphere) have been observed to move in
  the stratospheric wind field, merge and strengthen to generate thermal
  differences considerably larger than those reported in our initial study
  (Fig. 1, from IRTF/MIRSI, May 22 2011).

---------------------------------------------------------
Title: The December 2010 outbreak of a major storm in Saturn's
atmosphere: Observations and models
Authors: Sanchez-Lavega, A.; Del Río-Gaztelurrutia, T.; Hueso,
   R.; Gómez-Forrellad, J. M.; Sanz-Requena, J. F.; Legarreta, J.;
   García-Melendo, E.; Colas, F.; Lecacheux, J.; Fletcher, L. N.;
   Barrado-Navascués, D.; Parker, D.
2011epsc.conf..400S    Altcode: 2011DPS....43..400S
  On December 5, 2010, a major storm erupted in Saturn's northern
  hemisphere at a planetographic latitude of 37.7 deg [1]. These phenomena
  are known as "Great White Spots" (GWS) and they have been observed
  once per Saturn year since the first case confidently reported in
  1876. The last event occurred at Saturn's Equator in 1990 [2]. A
  GWS differs from similar smaller-scale storms in that it generates a
  planetary-scale disturbance that spreads zonally spanning the whole
  latitude band. Studies of the 1990 case indicated that the storm
  produced a long-term substantial change in the cloud and haze structure
  around the tropopause level, and in the equatorial winds. We report on
  the evolution and motions of the new GWS and its associated disturbance
  during the months following the outbreak, based mainly on high quality
  images obtained in the visual range submitted to the International Outer
  Planet Watch PVOL database [3], with the 1m telescope at Pic-du-Midi
  Observatory and 2.2 m telescope at Calar Alto Observatory. The high
  temporal sampling and coverage allowed us to study the dynamics of the
  GWS in detail and the multi-wavelength observations provide information
  on its cloud top structure. We present non-linear simulations using the
  EPIC code of the evolution of the potential vorticity generated by an
  impulsive and localized Gaussian heat pulse that compare extraordinary
  well to the observed cloud field evolution.

---------------------------------------------------------
Title: Uranus' cloud structure and scattering particle properties
    from IRTF SpeX observations
Authors: Tice, D. S.; Irwin, P. G. J.; Fletcher, L. N.; Teanby, N. A.;
   Orton, G. S.; Davis, G. R.
2011epsc.conf..143T    Altcode: 2011DPS....43..143T
  Observations of Uranus were made in August 2009 with the SpeX
  spectrograph at the NASA Infrared Telescope Facility (IRTF). Analysed
  spectra range from 0.8 to 1.8 μm at a spatial resolution of 0.5" and
  a spectral resolution of R = 1,200. Spectra from 0.818 to 0.834 μm,
  a region characterised by both strong hydrogen quadrupole and methane
  absorptions are considered to determine methane content. Evidence
  indicates that methane abundance varies with latitude. NEMESIS, an
  optimal estimation retrieval code with full-scattering capability, is
  employed to analyse the full range of data. Cloud and haze properties
  in the upper troposphere and stratosphere are characterised, and are
  consistent with other current literature. New information on single
  scattering albedos and particle size distributions are inferred.

---------------------------------------------------------
Title: The EVE Doppler Sensitivity and Flare Observations
Authors: Hudson, H. S.; Woods, T. N.; Chamberlin, P. C.; Fletcher,
   L.; Del Zanna, G.; Didkovsky, L.; Labrosse, N.; Graham, D.
2011SoPh..273...69H    Altcode: 2011SoPh..tmp..362H
  The Extreme-ultraviolet Variability Experiment (EVE; see Woods et al.,
  2009) obtains continuous EUV spectra of the Sun viewed as a star. Its
  primary objective is the characterization of solar spectral irradiance,
  but its sensitivity and stability make it extremely interesting for
  observations of variability on time scales down to the limit imposed
  by its basic 10 s sample interval. In this paper we characterize the
  Doppler sensitivity of the EVE data. We find that the 30.4 nm line of
  He II has a random Doppler error below 0.001 nm (1 pm, better than 10
  km s<SUP>−1</SUP> as a redshift), with ample stability to detect
  the orbital motion of its satellite, the Solar Dynamics Observatory
  (SDO). Solar flares also displace the spectrum, both because of Doppler
  shifts and because of EVE's optical layout, which (as with a slitless
  spectrograph) confuses position and wavelength. As a flare develops,
  the centroid of the line displays variations that reflect Doppler shifts
  and therefore flare dynamics. For the impulsive phase of the flare
  SOL2010-06-12, we find the line centroid to have a redshift of 16.8 ±
  5.9 km s<SUP>−1</SUP> relative to that of the flare gradual phase
  (statistical errors only). We find also that high-temperature lines,
  such as Fe XXIV 19.2 nm, have well-determined Doppler components for
  major flares, with decreasing apparent blueshifts as expected from
  chromospheric evaporation flows.

---------------------------------------------------------
Title: Elusive Ethylene Detected in Saturn's Northern Storm Region
Authors: Hesman, B. E.; Bjoraker, G. L.; Sada, P. V.; Achterberg,
   R. K.; Jennings, D. E.; Lunsford, A. W.; Boyle, R. J.; Romani, P. N.;
   Simon-Miller, A. A.; Nixon, C. A.; Fletcher, L. N.; Irwin, P. G. J.
2011epsc.conf.1222H    Altcode: 2011DPS....43.1222H
  The massive eruption at 40°N (planetographic latitude) in December 2010
  has produced significant and lasting effects in the northern hemisphere
  on temperature and species abundances [1]. The northern storm region
  has been observed on many occasions in between January and May of
  2011 by Cassini's Composite Infrared Spectrometer (CIRS). In May 2011
  temperatures in the stratosphere greater than 220K were derived from
  CIRS spectra in the regions referred to as "beacons" (warm regions in
  the stratosphere). Ethylene (C2H4) has been detected in a beacon in
  Saturn's northern storm region using CIRS. Ground-based observations
  using the high-resolution spectrometer Celeste on the McMath-Pierce
  Telescope on May 15, 2011 were used to confirm the detection. Early
  analysis indicate ethylene volume mixing ratios of 3x10-8 at 2 mbar.

---------------------------------------------------------
Title: JUICE (JUpiter ICy moon Explorer): a European-led mission to
    the Jupiter system
Authors: Dougherty, M. K.; Grasset, O.; Bunce, E.; Coustenis,
   A.; Titov, D. V.; Erd, C.; Blanc, M.; Coates, A. J.; Coradini,
   A.; Drossart, P.; Fletcher, L.; Hussmann, H.; Jaumann, R.; Krupp,
   N.; Prieto-Ballesteros, O.; Tortora, P.; Tosi, F.; van Hoolst, T.;
   Lebreton, J. -P.
2011epsc.conf.1343D    Altcode: 2011DPS....43.1343D
  The former ESA-NASA EJSM-Laplace mission is being reformulated by ESA
  as a European-led single spacecraft mission to the Jovian system. The
  concept has been recently renamed JUICE (JUpiter ICy moon Explorer). The
  new mission is based on the design of the Jupiter Ganymede Orbiter
  (JGO) - the ESA flight element of EJSM-Laplace.

---------------------------------------------------------
Title: Seasonal Variations of Hydrocarbons in Saturn's Stratosphere
Authors: Sinclair, J. A.; Irwin, P. G. J.; Fletcher, L. N.; Hurley,
   J.; Merlet, C.
2011epsc.conf..511S    Altcode: 2011DPS....43..511S
  We present a study of the seasonal variations of hydrocarbons in
  the stratosphere of Saturn. Meridional variations of the abundances
  of hydrocarbons such as acetylene (C2H2) and ethane (C2H6) have
  previously been determined, in particular using observations from
  the Cassini/CIRS (Composite Infrared Spectrometer) instrument. Such
  studies have used Cassini data obtained during the prime mission (2004 -
  2008) therefore studying Saturn from shortly after summer solstice to
  'autumn' in the Southern Hemisphere. With the occurence of the vernal
  equinox in August 2009, Saturn's northern hemisphere is now approaching
  summer solstice. We aim to determine the response of the hydrocarbon
  photochemistry as a result of seasonal changes.

---------------------------------------------------------
Title: Saturn's Enigmatic "String of Pearls" and Northern Storm of
2010-2011: Manifestations of a Common Dynamical Mechanism?
Authors: Baines, K.; Momary, T.; Fletcher, L.; Showman, A.; Brown,
   R.; Buratti, B.; Clark, R.; Nicholson, P.; Go, C.; Wesley, A.
2011epsc.conf.1658B    Altcode: 2011DPS....43.1658B
  The "String of Pearls" (SoP) and the Northern Storm on Saturn near 34o
  north latitude may both be manifestations of convective processes at
  depth. As one possibility, the SoP may be a set of von Kármán vortex
  street features with convectively-driven updrafts as the driving
  obstacles. VIMS observations show marked increases in the size and
  latitudinal separation of the pearls (vortices) during the year prior
  to storm eruption, indicative of a growing convective system that
  may have subsequently erupted as a major thunderstorm. Other common
  convective mechanisms (uplift-driven Rossby waves, vortex-shedding
  from rising updrafts) may be possible. New VIMS images and spectra of
  the thunderstorm and SoP are presented.

---------------------------------------------------------
Title: The 2010-2011 Revival of Jupiter's South Equatorial Belt:
    Perturbations of Temperatures, Clouds and Composition from Infrared
    Observations
Authors: Orton, G.; Fletcher, L.; Yanamandra-Fisher, P.;
   Sanchez-Lavega, A.; Perez-Hoyos, S.; de Pater, I.; Wong, M.; Goetz,
   R.; Valkov, S.; Greco, J.; Edwards, M.; Rogers, J.; Baines, K.
2011epsc.conf..673O    Altcode: 2011DPS....43..673O
  On 2010 November 9, a perturbation appeared in Jupiter's South
  Equatorial Belt (SEB), which began a classical "revival" of the
  SEB, returning the entire axisymmetric region to its normal dark
  color from its anomalous, light, "faded" state. The early revival is
  marked by strong upwelling gas at the outbreak location, to the west
  of which appear alternating clear and cloudy regions. Clear regions
  are correlated with dark clouds near the outbreak and in a southern
  retrograding branch but less so in a northern prograding branch. A
  5-μm image from 2010 March 1 shows much of the SEB closer to a
  pre-faded state.

---------------------------------------------------------
Title: Investigation of the Photochemistry in Saturn's Ring Shadowed
Atmosphere: Production Rates of Key Atmospheric Molecules
Authors: Edgington, S. G.; Atreya, S. K.; Wilson, E. H.; Baines,
   K. H.; West, R. A.; Bjoraker, G. L.; Fletcher, L. N.
2011epsc.conf.1710E    Altcode: 2011DPS....43.1710E
  Cassini has been orbiting Saturn for well over six years. During
  this epoch, the ring shadow has moved from covering a relatively large
  portion of the northern hemisphere to covering a small region just south
  of the equator (see Figure 1). For example, at Saturn Orbit Insertion
  (SOI; July 1, 2004), the ring plane was inclined by ~24 degrees relative
  to the Sun-Saturn vector. At this time, the projection of the B-ring
  onto Saturn reached as far as 40ºN along the central meridian (~52ºN
  at the terminator). At its maximum extent, the ring shadow can reach
  as far as 48ºN (~58ºN at the terminator). The net result, is that the
  intensity of both ultraviolet and visible sunlight penetrating into any
  particular northern/southern latitude will vary depending on Saturn's
  tilt relative to the Sun and the optical thickness of each ring system
  (see Figure 2). Previous work [1] looked at the variation of the solar
  flux as a function of solar inclination, i.e. season (see Figure 3). The
  current work looks at the impact of the oscillating ring shadow on the
  photodissociation and production rates of key molecules in Saturn's
  stratosphere and upper troposphere over time. Beginning with methane,
  the impact on production and loss rates of the long-lived photochemical
  products leading to haze formation are examined at several latitudes
  over a Saturn year. We also look at the impacts on phosphine abundance,
  a disequilibrium species whose presence in the upper troposphere is
  a tracer of convection processes in the deep atmosphere. Comparison
  to the corresponding rates for the clear atmosphere and the effect of
  dynamical mixing will be presented.

---------------------------------------------------------
Title: An Observational Overview of Solar Flares
Authors: Fletcher, L.; Dennis, B. R.; Hudson, H. S.; Krucker, S.;
   Phillips, K.; Veronig, A.; Battaglia, M.; Bone, L.; Caspi, A.; Chen,
   Q.; Gallagher, P.; Grigis, P. T.; Ji, H.; Liu, W.; Milligan, R. O.;
   Temmer, M.
2011SSRv..159...19F    Altcode: 2011SSRv..tmp..261F; 2011arXiv1109.5932F
  We present an overview of solar flares and associated phenomena,
  drawing upon a wide range of observational data primarily from the
  RHESSI era. Following an introductory discussion and overview of
  the status of observational capabilities, the article is split into
  topical sections which deal with different areas of flare phenomena
  (footpoints and ribbons, coronal sources, relationship to coronal mass
  ejections) and their interconnections. We also discuss flare soft X-ray
  spectroscopy and the energetics of the process. The emphasis is to
  describe the observations from multiple points of view, while bearing
  in mind the models that link them to each other and to theory. The
  present theoretical and observational understanding of solar flares is
  far from complete, so we conclude with a brief discussion of models,
  and a list of missing but important observations.

---------------------------------------------------------
Title: Evolution of sunspot properties during solar cycle 23
Authors: Watson, F. T.; Fletcher, L.; Marshall, S.
2011A&A...533A..14W    Altcode: 2011arXiv1108.4285W
  Context. The long term study of the Sun is necessary if we are to
  determine the evolution of sunspot properties and thereby inform
  modeling of the solar dynamo, particularly on scales of a solar
  cycle. <BR /> Aims: We aim to determine a number of sunspot properties
  over cycle 23 using the uniform database provided by the SOHO Michelson
  Doppler Imager data. We focus in particular on their distribution on
  the solar disk, maximum magnetic field and umbral/penumbral areas. We
  investigate whether the secular decrease in sunspot maximum magnetic
  field reported in Kitt Peak data is present also in MDI data. <BR />
  Methods: We have used the Sunspot Tracking And Recognition Algorithm
  (STARA) to detect all sunspots present in the SOHO Michelson Doppler
  Imager continuum data giving us 30 084 separate detections. We record
  information on the sunspot locations, area and magnetic field properties
  as well as corresponding information for the umbral areas detected
  within the sunspots, and track them through their evolution. <BR />
  Results: We find that the total visible umbral area is 20-40% of
  the total visible sunspot area regardless of the stage of the solar
  cycle. We also find that the number of sunspots observed follows
  the Solar Influences Data Centre international sunspot number with
  some interesting deviations. Finally, we use the magnetic information
  in our catalogue to study the long term variation of magnetic field
  strength within sunspot umbrae and find that it increases and decreases
  along with the sunspot number. However, if we were to assume a secular
  decrease as was reported in the Kitt Peak data and take into account
  sunspots throughout the whole solar cycle we would find the maximum
  umbral magnetic fields to be decreasing by 23.6 ± 3.9 Gauss per year,
  which is far less than has previously been observed by other studies
  (although measurements are only available for solar cycle 23). If we
  only look at the declining phase of cycle 23 we find the decrease in
  sunspot magnetic fields to be 70 Gauss per year.

---------------------------------------------------------
Title: Recent Advances in Understanding Particle Acceleration
    Processes in Solar Flares
Authors: Zharkova, V. V.; Arzner, K.; Benz, A. O.; Browning, P.;
   Dauphin, C.; Emslie, A. G.; Fletcher, L.; Kontar, E. P.; Mann, G.;
   Onofri, M.; Petrosian, V.; Turkmani, R.; Vilmer, N.; Vlahos, L.
2011SSRv..159..357Z    Altcode: 2011SSRv..tmp..156Z; 2011SSRv..tmp..249Z; 2011SSRv..tmp..232Z;
   2011arXiv1110.2359Z; 2011SSRv..tmp..278Z
  We review basic theoretical concepts in particle acceleration,
  with particular emphasis on processes likely to occur in regions of
  magnetic reconnection. Several new developments are discussed, including
  detailed studies of reconnection in three-dimensional magnetic field
  configurations (e.g., current sheets, collapsing traps, separatrix
  regions) and stochastic acceleration in a turbulent environment. Fluid,
  test-particle, and particle-in-cell approaches are used and results
  compared. While these studies show considerable promise in accounting
  for the various observational manifestations of solar flares, they
  are limited by a number of factors, mostly relating to available
  computational power. Not the least of these issues is the need to
  explicitly incorporate the electrodynamic feedback of the accelerated
  particles themselves on the environment in which they are accelerated. A
  brief prognosis for future advancement is offered.

---------------------------------------------------------
Title: Long-term evolution of the aerosol debris cloud produced by
    the 2009 impact on Jupiter
Authors: Sánchez-Lavega, A.; Orton, G. S.; Hueso, R.; Pérez-Hoyos,
   S.; Fletcher, L. N.; García-Melendo, E.; Gomez-Forrellad, J. M.;
   de Pater, I.; Wong, M.; Hammel, H. B.; Yanamandra-Fisher, P.;
   Simon-Miller, A.; Barrado-Izagirre, N.; Marchis, F.; Mousis, O.;
   Ortiz, J. L.; García-Rojas, J.; Cecconi, M.; Clarke, J. T.; Noll,
   K.; Pedraz, S.; Wesley, A.; Kalas, P.; McConnell, N.; Golisch, W.;
   Griep, D.; Sears, P.; Volquardsen, E.; Reddy, V.; Shara, M.; Binzel,
   R.; Grundy, W.; Emery, J.; Rivkin, A.; Thomas, C.; Trilling, D.;
   Bjorkman, K.; Burgasser, A. J.; Campins, H.; Sato, T. M.; Kasaba,
   Y.; Ziffer, J.; Mirzoyan, R.; Fitzgerald, M.; Bouy, H.; International
   Outer Planet Watch Team (IOPW-PVOL)
2011Icar..214..462S    Altcode: 2011Icar..214..462I
  We present a study of the long-term evolution of the cloud of aerosols
  produced in the atmosphere of Jupiter by the impact of an object on
  19 July 2009 (Sánchez-Lavega, A. et al. [2010]. Astrophys. J. 715,
  L155-L159). The work is based on images obtained during 5 months from
  the impact to 31 December 2009 taken in visible continuum wavelengths
  and from 20 July 2009 to 28 May 2010 taken in near-infrared deep
  hydrogen-methane absorption bands at 2.1-2.3 μm. The impact cloud
  expanded zonally from ∼5000 km (July 19) to 225,000 km (29 October,
  about 180° in longitude), remaining meridionally localized within a
  latitude band from 53.5°S to 61.5°S planetographic latitude. During
  the first two months after its formation the site showed heterogeneous
  structure with 500-1000 km sized embedded spots. Later the reflectivity
  of the debris field became more homogeneous due to clump mergers. The
  cloud was mainly dispersed in longitude by the dominant zonal winds and
  their meridional shear, during the initial stages, localized motions
  may have been induced by thermal perturbation caused by the impact's
  energy deposition. The tracking of individual spots within the impact
  cloud shows that the westward jet at 56.5°S latitude increases its
  eastward velocity with altitude above the tropopause by 5-10 m s
  <SUP>-1</SUP>. The corresponding vertical wind shear is low, about 1
  m s <SUP>-1</SUP> per scale height in agreement with previous thermal
  wind estimations. We found evidence for discrete localized meridional
  motions with speeds of 1-2 m s <SUP>-1</SUP>. Two numerical models
  are used to simulate the observed cloud dispersion. One is a pure
  advection of the aerosols by the winds and their shears. The other
  uses the EPIC code, a nonlinear calculation of the evolution of the
  potential vorticity field generated by a heat pulse that simulates
  the impact. Both models reproduce the observed global structure of the
  cloud and the dominant zonal dispersion of the aerosols, but not the
  details of the cloud morphology. The reflectivity of the impact cloud
  decreased exponentially with a characteristic timescale of 15 days; we
  can explain this behavior with a radiative transfer model of the cloud
  optical depth coupled to an advection model of the cloud dispersion by
  the wind shears. The expected sedimentation time in the stratosphere
  (altitude levels 5-100 mbar) for the small aerosol particles forming
  the cloud is 45-200 days, thus aerosols were removed vertically over
  the long term following their zonal dispersion. No evidence of the
  cloud was detected 10 months after the impact.

---------------------------------------------------------
Title: Hinode/EIS plasma diagnostics in the flaring solar chromosphere
Authors: Graham, D. R.; Fletcher, L.; Hannah, I. G.
2011A&A...532A..27G    Altcode:
  Context. The impulsive phase of solar flares is a time of rapid energy
  deposition and heating in the lower solar atmosphere, leading to changes
  in the temperature, density, ionisation and velocity structure of
  this region. <BR /> Aims: We aim to study the lower atmosphere during
  the impulsive phase of a flare using imaging and spectroscopic data
  from Hinode/EIS, RHESSI and TRACE. We place these observations in
  context by using a wide range of temperature observations from each
  instrument. <BR /> Methods: We analyse sparse raster data from the
  Hinode/EIS spectrometer to derive the density and line-of-sight velocity
  in flare footpoints, in a GOES C6.6 flare observed on 05-June-2007. The
  raster duration was 150s across the centre of a small active region,
  allowing multiple exposures of the flare ribbons and footpoints. Using
  RHESSI and Hinode/XRT we test both non-thermal and thermal models for
  the HXR emission. <BR /> Results: During the flare impulsive phase, we
  find evidence from XRT for flare footpoints at temperatures exceeding
  7 MK. We measure the electron number density increasing up to a few
  ×10<SUP>10</SUP> cm<SUP>-3</SUP> in the footpoints, at temperatures
  of ~1.5-2 MK, accompanied by small downflows at temperatures below
  Fe XIII and upflows of up to ~140 km s<SUP>-1</SUP> at temperatures
  above. This is reasonable in the context of HXR diagnostics of the
  flare electron beam. The electrons inferred have sufficient energy to
  affect the chromospheric ionisation structure. <BR /> Conclusions: EIS
  sparse raster data coupled with RHESSI imaging and spectroscopy prove
  useful here in studying the lower atmosphere of solar flares, and in
  this event suggest heat deposition relatively high in the chromosphere
  drives chromospheric evaporation while increasing the observed electron
  densities at footpoints. However, from RHESSI spectral fitting it is
  not possible to say whether the data are more consistent with a model
  including a non-thermal beam, or purely thermal model.

---------------------------------------------------------
Title: Automated sunspot detection and the evolution of sunspot
    magnetic fields during solar cycle 23
Authors: Watson, Fraser; Fletcher, Lyndsay
2011IAUS..273...51W    Altcode: 2010arXiv1009.5884W
  The automated detection of solar features is a technique which
  is relatively underused but if we are to keep up with the flow of
  data from spacecraft such as the recently launched Solar Dynamics
  Observatory, then such techniques will be very valuable to the solar
  community. Automated detection techniques allow us to examine a large
  set of data in a consistent way and in relatively short periods of
  time allowing for improved statistics to be carried out on any results
  obtained. This is particularly useful in the field of sunspot study
  as catalogues can be built with sunspots detected and tracked without
  any human intervention and this provides us with a detailed account of
  how various sunspot properties evolve over time. This article details
  the use of the Sunspot Tracking And Recognition Algorithm (STARA)
  to create a sunspot catalogue. This catalogue is then used to analyse
  the magnetic fields in sunspot umbrae from 1996-2010, taking in the
  whole of solar cycle 23.

---------------------------------------------------------
Title: Deep winds beneath Saturn's upper clouds from a seasonal
    long-lived planetary-scale storm
Authors: Sánchez-Lavega, A.; del Río-Gaztelurrutia, T.; Hueso,
   R.; Gómez-Forrellad, J. M.; Sanz-Requena, J. F.; Legarreta, J.;
   García-Melendo, E.; Colas, F.; Lecacheux, J.; Fletcher, L. N.;
   Barrado y Navascués, D.; Parker, D.; International Outer Planet
   Watch Team; Akutsu, T.; Barry, T.; Beltran, J.; Buda, S.; Combs, B.;
   Carvalho, F.; Casquinha, P.; Delcroix, M.; Ghomizadeh, S.; Go, C.;
   Hotershall, J.; Ikemura, T.; Jolly, G.; Kazemoto, A.; Kumamori, T.;
   Lecompte, M.; Maxson, P.; Melillo, F. J.; Milika, D. P.; Morales, E.;
   Peach, D.; Phillips, J.; Poupeau, J. J.; Sussenbach, J.; Walker, G.;
   Walker, S.; Tranter, T.; Wesley, A.; Wilson, T.; Yunoki, K.
2011Natur.475...71S    Altcode:
  Convective storms occur regularly in Saturn's atmosphere. Huge storms
  known as Great White Spots, which are ten times larger than the regular
  storms, are rarer and occur about once per Saturnian year (29.5 Earth
  years). Current models propose that the outbreak of a Great White Spot
  is due to moist convection induced by water. However, the generation of
  the global disturbance and its effect on Saturn's permanent winds have
  hitherto been unconstrained by data, because there was insufficient
  spatial resolution and temporal sampling to infer the dynamics of
  Saturn's weather layer (the layer in the troposphere where the cloud
  forms). Theoretically, it has been suggested that this phenomenon
  is seasonally controlled. Here we report observations of a storm
  at northern latitudes in the peak of a weak westward jet during the
  beginning of northern springtime, in accord with the seasonal cycle
  but earlier than expected. The storm head moved faster than the jet,
  was active during the two-month observation period, and triggered
  a planetary-scale disturbance that circled Saturn but did not
  significantly alter the ambient zonal winds. Numerical simulations
  of the phenomenon show that, as on Jupiter, Saturn's winds extend
  without decay deep down into the weather layer, at least to the
  water-cloud base at pressures of 10-12bar, which is much deeper than
  solar radiation penetrates.

---------------------------------------------------------
Title: Solar flares: observations vs simulations
Authors: Rubio da Costa, Fatima; Zuccarello, Francesca; Labrosse,
   Nicolas; Fletcher, Lyndsay; Prosecký, Tomáš; Kašparová, Jana
2011IAUS..274..182R    Altcode:
  In order to study the properties of faint, moderate and bright flares,
  we simulate the conditions of the solar atmosphere using a radiative
  hydrodynamic model (Abbett &amp; Hawley, 1999). A constant beam of
  non-thermal electrons is injected at the apex of a 1D coronal loop and
  heating from thermal soft X-ray emission is included. We compare the
  results with some observational data in Ly-α (using TRACE 1216 and
  1600 Å data and estimating the “pure” Ly-α emission) and in Hα
  (data taken with a Multichannel Flare Spectrograph, at the Ondrejov
  Observatory).

---------------------------------------------------------
Title: The Magnetic and Dynamic Properties of Flaring Active Regions
Authors: Watson, Fraser; Fletcher, L.
2011SPD....42.1201W    Altcode: 2011BAAS..43S.1201W
  As solar cycle 24 begins, the return of active regions and solar flares
  provides new opportunities for the study of the sun, particularly with
  the recently launched Solar Dynamics Orbiter. This allows these regions
  to be studied in more detail than has previously been possible. We have
  developed a magnetic segmentation algorithm that allows us to examine
  magnetic structures within active region magnetograms and track their
  evolution in space and time. With this, we can build up a picture of
  the photospheric properties of the active region before and after
  solar flares. We can then examine the structures for changes that
  occur around the time of flaring and compare these with changes seen
  in other active regions at times of emergence, flaring and decay. We
  present the findings of a study of flaring active regions, most of
  which come from SOHO/MDI data and two use data from SDO/HMI. These
  two regions observed by HMI include two of the strongest flares seen
  during the beginning of solar cycle 24 whilst the MDI regions are
  very active regions from the peak of solar cycle 23. In this way we
  can also compare any changes observed between the two cycles.

---------------------------------------------------------
Title: Doppler Signatures In EVE Spectra
Authors: Hudson, Hugh S.; Chamberlin, P.; Woods, T.; Fletcher, L.;
   Graham, D.
2011SPD....42.2124H    Altcode: 2011BAAS..43S.2124H
  The Extreme-ultraviolet Variability Experiment (EVE) on SDO is providing
  a comprehensive set of EUV spectra of the Sun as a star. The routine
  sampling is with 10 s integrations at a resolution of 0.1 nm. Although
  this resolution corresponds to only some 1000 km/s in velocity space,
  we demonstrate that the instrument is stable enough to detect the SDO
  orbital motion of a few km/s readily in the bright He II line at 30.4
  nm. We find the random error in the centroid location of this line to be
  less than one pm (less than 1 km/s) per 10 s integration. We also note
  systematic effects from a variety of causes. For flare observations,
  the line centroid position depends on the flare position. We discuss the
  calibration of this effect and show that EVE can nonetheless provide
  clear Doppler signatures that may be interpreted in terms of flare
  dynamics. This information has some value in and of itself, because of
  EVE's sensitivity, but we feel that it will be of greatest importance
  when combined with imagery (e.g., via AIA) a modeling. We discuss flare
  signatures in several events, e.g. the gamma-ray flare SOL2010-06-12
  and SOL2011-02-16T:07:44, taking advantage of AIA image comparisons.

---------------------------------------------------------
Title: Uranus’ cloud structure and seasonal variability from
    Gemini-North and UKIRT observations
Authors: Irwin, P. G. J.; Teanby, N. A.; Davis, G. R.; Fletcher,
   L. N.; Orton, G. S.; Tice, D.; Kyffin, A.
2011Icar..212..339I    Altcode:
  Observations of Uranus were made in September 2009 with the
  Gemini-North telescope in Hawaii, using both the NIFS and NIRI
  instruments. Observations were acquired in Adaptive Optics mode and
  have a spatial resolution of approximately 0.1″. <P />NIRI images
  were recorded with three spectral filters to constrain the overall
  appearance of the planet: J, H-continuum and CH<SUB>4</SUB>(long),
  and long slit spectroscopy measurements were also made (1.49-1.79 μm)
  with the entrance slit aligned on Uranus’ central meridian. To acquire
  spectra from other points on the planet, the NIFS instrument was used
  and its 3″ × 3″ field of view stepped across Uranus’ disc. These
  observations were combined to yield complete images of Uranus at
  2040 wavelengths between 1.476 and 1.803 μm. <P />The observed
  spectra along Uranus central meridian were analysed with the NEMESIS
  retrieval tool and used to infer the vertical/latitudinal variation
  in cloud optical depth. We find that the 2009 Gemini data perfectly
  complement our observations/conclusions from UKIRT/UIST observations
  made in 2006-2008 and show that the north polar zone at 45°N has
  continued to steadily brighten while that at 45°S has continued
  to fade. The improved spatial resolution of the Gemini observations
  compared with the non-AO UKIRT/UIST data removes some of the earlier
  ambiguities with our previous analyses and shows that the opacity of
  clouds deeper than the 2-bar level does indeed diminish towards the
  poles and also reveals a darkening of the deeper cloud deck near the
  equator, perhaps coinciding with a region of subduction. We find that
  the clouds at 45°N,S lie at slightly lower pressures than the clouds
  at more equatorial latitudes, which suggests that they might possibly
  be composed of a different condensate, presumably CH<SUB>4</SUB> ice,
  rather than H<SUB>2</SUB>S or NH<SUB>3</SUB> ice, which is assumed for
  the deeper cloud. In addition, analysis of the centre-to-limb curves
  of both the Gemini/NIFS and earlier UKIRT/UIST IFU observations shows
  that the main cloud deck has a well-defined top, and also allows us
  to better constrain the particle scattering properties. <P />Overall,
  Uranus appeared to be less convectively active in 2009 than in the
  previous 3 years, which suggests that now the northern spring equinox
  (which occurred in 2007) is passed the atmosphere is settling back into
  the quiescent state seen by Voyager 2 in 1986. However, a number of
  discrete clouds were still observed, with one at 15°N found to lie
  near the 500 mb level, while another at 30°N, was seen to be much
  higher at near the 200 mb level. Such high clouds are assumed to be
  composed of CH<SUB>4</SUB> ice.

---------------------------------------------------------
Title: Relationship Between Hard and Soft X-ray Emission Components
    of a Solar Flare
Authors: Guo, Jingnan; Liu, Siming; Fletcher, Lyndsay; Kontar,
   Eduard P.
2011ApJ...728....4G    Altcode: 2010arXiv1012.4346G
  X-ray observations of solar flares routinely reveal an impulsive
  high-energy and a gradual low-energy emission component, whose
  relationship is one of the key issues of solar flare study. The gradual
  and impulsive emission components are believed to be associated with,
  respectively, the thermal and nonthermal components identified in
  spectral fitting. In this paper, a prominent ~50 s hard X-ray (HXR)
  pulse of a simple GOES class C7.5 flare on 2002 February 20 is used to
  study the association between high-energy, non-thermal, and impulsive
  evolution, and low-energy, thermal, and gradual evolution. We use
  regularized methods to obtain time derivatives of photon fluxes to
  quantify the time evolution as a function of photon energy, obtaining
  a break energy between impulsive and gradual behavior. These break
  energies are consistent with a constant value of ~11 keV in agreement
  with those found spectroscopically between thermal and non-thermal
  components, but the relative errors of the former are greater than
  15% and much greater than the few percent errors found from the
  spectral fitting. These errors only weakly depend on assuming an
  underlying spectral model for the photons, pointing to the current
  data being inadequate to reduce the uncertainties rather than there
  being a problem associated with an assumed model. The time derivative
  method is used to test for the presence of a "pivot energy" in this
  flare. Although these pivot energies are marginally consistent with
  a constant value of ~9 keV, its values in the HXR rise phase appear
  to be lower than those in the decay phase. Assuming that electrons
  producing the high-energy component have a power-law distribution and
  are accelerated from relatively hot regions of a background plasma
  responsible for the observed thermal component, a low limit is obtained
  for the low-energy cutoff. This limit is always lower than the break and
  pivot energies and is located in the tail of the Maxwellian distribution
  of the thermal component.

---------------------------------------------------------
Title: Jupiter In The Crosshairs: Recent Impacts And Their
    Implications
Authors: Hammel, Heidi B.; de Pater, I.; Simon-Miller, A. A.; Fletcher,
   L.; Boslough, M. B.; Orton, G. S.; Djorgovski, G.; Yanamandra-Fisher,
   P.; Wong, M. H.; Hueso, R.; Sánchez-Lavega, A.; Go, C.; Wesley, A.;
   Pérez-Hoyos, S.; Edwards, M.; Clarke, J. T.; Noll, K. S.
2011AAS...21715608H    Altcode: 2011BAAS...4315608H
  No abstract at ADS

---------------------------------------------------------
Title: The atmospheric influence, size and possible asteroidal nature
    of the July 2009 Jupiter impactor
Authors: Orton, G. S.; Fletcher, L. N.; Lisse, C. M.; Chodas, P. W.;
   Cheng, A.; Yanamandra-Fisher, P. A.; Baines, K. H.; Fisher, B. M.;
   Wesley, A.; Perez-Hoyos, S.; de Pater, I.; Hammel, H. B.; Edwards,
   M. L.; Ingersoll, A. P.; Mousis, O.; Marchis, F.; Golisch, W.;
   Sanchez-Lavega, A.; Simon-Miller, A. A.; Hueso, R.; Momary, T. W.;
   Greene, Z.; Reshetnikov, N.; Otto, E.; Villar, G.; Lai, S.; Wong, M. H.
2011Icar..211..587O    Altcode:
  Near-infrared and mid-infrared observations of the site of the 2009
  July 19 impact of an unknown object with Jupiter were obtained within
  days of the event. The observations were used to assess the properties
  of a particulate debris field, elevated temperatures, and the extent
  of ammonia gas redistributed from the troposphere into Jupiter's
  stratosphere. The impact strongly influenced the atmosphere in a
  central region, as well as having weaker effects in a separate field
  to its west, similar to the Comet Shoemaker-Levy 9 (SL9) impact sites
  in 1994. Temperatures were elevated by as much as 6 K at pressures
  of about 50-70 mbar in Jupiter's lower stratosphere near the center
  of the impact site, but no changes above the noise level (1 K) were
  observed in the upper stratosphere at atmospheric pressures less than
  ∼1 mbar. The impact transported at least ∼2 × 10 <SUP>15</SUP>
  g of gas from the troposphere to the stratosphere, an amount less
  than derived for the SL9 C fragment impact. From thermal heating
  and mass-transport considerations, the diameter of the impactor was
  roughly in the range of 200-500 m, assuming a mean density of 2.5
  g/cm <SUP>3</SUP>. Models with temperature perturbations and ammonia
  redistribution alone are unable to fit the observed thermal emission;
  non-gray emission from particulate emission is needed. Mid-infrared
  spectroscopy of material delivered by the impacting body implies that,
  in addition to a silicate component, it contains a strong signature
  that is consistent with silica, distinguishing it from SL9, which
  contained no evidence for silica. Because no comet has a significant
  abundance of silica, this result is more consistent with a "rocky"
  or "asteroidal" origin for the impactor than an "icy" or "cometary"
  one. This is surprising because the only objects generally considered
  likely to collide with Jupiter and its satellites are Jupiter-Family
  Comets, whose populations appear to be orders of magnitude larger
  than the Jupiter-encountering asteroids. Nonetheless, our conclusion
  that there is good evidence for at least a major asteroidal component
  of the impactor composition is also consistent both with constraints
  on the geometry of the impactor and with results of contemporaneous
  Hubble Space Telescope observations. If the impact was not simply a
  statistical fluke, then our conclusion that the impactor contained
  more rocky material than was the case for the desiccated Comet SL9
  implies a larger population of Jupiter-crossing asteroidal bodies than
  previously estimated, an asteroidal component within the Jupiter-Family
  Comet population, or compositional differentiation within these bodies.

---------------------------------------------------------
Title: Jupiter's stratospheric hydrocarbons and temperatures after
    the July 2009 impact from VLT infrared spectroscopy
Authors: Fletcher, L. N.; Orton, G. S.; de Pater, I.; Mousis, O.
2010A&A...524A..46F    Altcode:
  <BR /> Aims: Thermal infrared imaging and spectroscopy of the July 19,
  2009 Jupiter impact site has been used to identify unique features
  of the physical and chemical atmospheric response to this unexpected
  collision. <BR /> Methods: Images and high-resolution spectra of
  methane, ethane and acetylene emission (7-13 μm) from the 2009 impact
  site were obtained by the Very Large Telescope (VLT) mid-infrared
  camera/spectrometer instrument, VISIR. An optimal estimation retrieval
  algorithm was used to determine the atmospheric temperatures and
  hydrocarbon distribution in the month following the impact. <BR />
  Results: Ethane spectra at 12.25 μm could not be explained by a
  rise in temperature alone. Ethane was enhanced by 1.7-3.2 times the
  background abundance on July 26, implying production as the result of
  shock chemistry in a high C/O ratio environment, favouring an asteroidal
  origin for the 2009 impactor. Small enhancements in acetylene emission
  were also observed over the impact site. However, no excess methane
  emission was found over the impact longitude, either with broadband
  7.9-μm imaging 21 h after the impact, or with center-to-limb scans of
  strong and weak methane lines between 7.9 and 8.1 μm in the ensuing
  days, indicating either extremely rapid cooling in the initial stages,
  or an absence of heating in the upper stratosphere (p &lt; 10 mbar)
  due to the near-horizontal orientation of the impact. Models of 12.3-μm
  spectra are consistent with a ≈ 3 K rise in the lower stratosphere (p
  &gt; 10 mbar), though this solution is highly dependent on the spectral
  properties of stratospheric debris. The enhanced ethane emission was
  localised over the impact streak, and was diluted in the ensuing weeks
  by redistribution of heated gases by zonal flow and mixing with the
  unperturbed jovian air. <BR /> Conclusions: The different thermal
  energy deposition profiles, in addition to the highly reducing (C/O
  &gt; 1) environment and shallow impactor angle, suggest that (a) the
  2009 plume and shock-fronts did not reach the sub-microbar altitudes
  of the Shoemaker-Levy 9 plumes; and (b) models of a cometary impact are
  not directly applicable to the unique impact circumstances of July 2009.

---------------------------------------------------------
Title: Compositional Constraints on the Atmospheres of Uranus and
    Neptune from Herschel and Spitzer Spectroscopic Observations
Authors: Orton, G. S.; Moreno, R.; Lellouch, E.; Fletcher, L. N.;
   Hartogh, P.; Jarchow, C.; Feuchtgruber, H.; Line, M. R.; Herschel
   Key Project On Water; Related Chemistry in Solar System Team
2010AGUFM.P14A..07O    Altcode:
  Key elements of planetary compositions provide one of the most
  fundamental constraints on the origins and evolution of major
  bodies in the solar system. For the icy giants, Uranus and Neptune,
  acquiring compositional information has been a challenge because
  of their faintness. Great strides have been made with the advent of
  cryogenically cooled space-borne telescopes, however, and we report here
  the most recent of these results from Spitzer and Herschel telescopes,
  the latter including data taken within the framework of the Key Project
  "Water and Related Chemistry in the Solar system". Our interpretation
  of these results is set in the context of earlier results obtained by
  the ISO LWS and SWS spectrometers, together with relevant Earth-based
  observations. We will specifically discuss the chemical inventory and
  abundances stratospheric hydrocarbons, the implications of thermal
  structure for deep atmospheric composition, and improved constraints
  on the D/H ratio in Neptune.

---------------------------------------------------------
Title: Solar Flares and the Chromosphere
Authors: Fletcher, L.; Turkmani, R.; Hudson, H. S.; Hawley, S. L.;
   Kowalski, A.; Berlicki, A.; Heinzel, P.
2010arXiv1011.4650F    Altcode:
  A white paper prepared for the Space Studies Board, National Academy
  of Sciences (USA), for its Decadal Survey of Solar and Space Physics
  (Heliophysics), reviewing and encouraging studies of flare physics in
  the chromosphere.

---------------------------------------------------------
Title: Unveiling Uranus' Clouds: New Observations From Gemini-North
    NIFS And NIRI
Authors: Irwin, Patrick G. J.; Teanby, N. A.; Davis, G. R.; Fletcher,
   L. N.; Orton, G.; Tice, D.
2010DPS....42.4404I    Altcode: 2010BAAS...42.1045I
  Observations of Uranus were made in September 2009 with the Gemini-North
  telescope in Hawaii, using both the NIFS and NIRI instruments. Adaptive
  optics were used to achieve a spatial resolution of approximately 0.1
  arcsec. <P />NIRI images were recorded with three spectral filters
  to constrain the overall appearance of the planet: J, H-continuum and
  CH4(long), and long slit spectra (1.49 to 1.79 microns) were obtained
  with the slit aligned on Uranus’ central meridian. In addition,
  the NIFS instrument was used to acquire spectra from other points
  on the planet, stepping the NIFS 3 x 3 arcsec field of view across
  Uranus’ disc. These observations were combined to yield complete
  images of Uranus at 2040 wavelengths between 1.476 and 1.803 microns
  with a spectral resolution of 5000. <P />The observed spectra along
  Uranus central meridian were analyzed with the NEMESIS retrieval
  tool and used to infer the vertical/latitudinal variation in cloud
  optical depth. We find that the 2009 Gemini data perfectly complement
  our observations/conclusions from UKIRT/UIST observations made in
  2006-2008 and show that the north polar zone at 45N has continued to
  steadily brighten while that at 45S has continued to fade. The improved
  spatial resolution of the Gemini observations compared with the non-AO
  UKIRT/UIST data remove many of the earlier ambiguities inherent in the
  previous analysis. <P />Overall, Uranus appeared to be less convectively
  active in 2009 than in the previous 3 years, which suggests that now
  the equinox (which occurred in 2007) is over the atmosphere is settling
  back into the quiescent state seen by Voyager 2 in 1986. However, one
  discrete cloud was captured in the NIFS observations and was estimated
  to lie at a pressure level of 300-400 mbar.

---------------------------------------------------------
Title: The Optical Depth of White-light Flare Continuum
Authors: Potts, Hugh; Hudson, Hugh; Fletcher, Lyndsay; Diver, Declan
2010ApJ...722.1514P    Altcode: 2010arXiv1004.1039P
  The white-light continuum emission of a solar flare remains a puzzle as
  regards its height of formation and its emission mechanism(s). This
  continuum and its extension into the near-UV contain the bulk of
  the energy radiated by a flare, and so its explanation is a high
  priority. We describe a method to determine the optical depth of the
  emitting layer and apply it to the well-studied flare of 2002 July
  15, making use of MDI pseudo-continuum intensity images. We find the
  optical depth of the visible continuum in all flare images, including
  an impulsive ribbon to be small, consistent with the observation of
  Balmer and Paschen edges in other events.

---------------------------------------------------------
Title: First Earth-based Detection of a Superbolide on Jupiter
Authors: Hueso, R.; Wesley, A.; Go, C.; Pérez-Hoyos, S.; Wong, M. H.;
   Fletcher, L. N.; Sánchez-Lavega, A.; Boslough, M. B. E.; de Pater, I.;
   Orton, G. S.; Simon-Miller, A. A.; Djorgovski, S. G.; Edwards, M. L.;
   Hammel, H. B.; Clarke, J. T.; Noll, K. S.; Yanamandra-Fisher, P. A.
2010ApJ...721L.129H    Altcode: 2010arXiv1009.1824H
  Cosmic collisions on planets cause detectable optical flashes that
  range from terrestrial shooting stars to bright fireballs. On 2010
  June 3 a bolide in Jupiter's atmosphere was simultaneously observed
  from the Earth by two amateur astronomers observing Jupiter in red and
  blue wavelengths. The bolide appeared as a flash of 2 s duration in
  video recording data of the planet. The analysis of the light curve
  of the observations results in an estimated energy of the impact of
  (0.9-4.0) × 10<SUP>15</SUP> J which corresponds to a colliding body of
  8-13 m diameter assuming a mean density of 2 g cm<SUP>-3</SUP>. Images
  acquired a few days later by the Hubble Space Telescope and other large
  ground-based facilities did not show any signature of aerosol debris,
  temperature, or chemical composition anomaly, confirming that the
  body was small and destroyed in Jupiter's upper atmosphere. Several
  collisions of this size may happen on Jupiter on a yearly basis. A
  systematic study of the impact rate and size of these bolides can enable
  an empirical determination of the flux of meteoroids in Jupiter with
  implications for the populations of small bodies in the outer solar
  system and may allow a better quantification of the threat of impacting
  bodies to Earth. The serendipitous recording of this optical flash
  opens a new window in the observation of Jupiter with small telescopes.

---------------------------------------------------------
Title: Vertical Cloud Structure Of The 2009 Jupiter Impact Based On
    HST/WFC3 Observations
Authors: Perez-Hoyos, Santiago; Sanz-Requena, J. F.; Sanchez-Lavega,
   A.; Wong, M.; Hueso, R.; Hammel, H. B.; Orton, G. S.; Fletcher,
   L. N.; de Pater, I.; Simon-Miller, A. A.; Clarke, J. T.; Noll, K.;
   Yanamandra-Fisher, P. A.
2010DPS....42.1107P    Altcode: 2010BAAS...42R1018P
  The impact of a body of unknown origin with Jupiter in July 2009
  (Sánchez-Lavega et al., Astrophys. J. Lett, Vol. 715, L155. 2010)
  produced an intense perturbation of the planet's atmosphere at the
  visible levels. The perturbation was caused by dense aerosol material;
  this strongly absorbing material expanded steadily as it was advected by
  the local winds. This phenomenon was observed at high spatial resolution
  by the Hubble Space Telescope in July, August, September and November
  2009 with recently installed Wide Field Camera 3. In this work, we
  present radiative transfer modeling of the observed reflectivity in the
  near UV (200nm) to near IR (950nm) range. The geometrical and spectral
  variations of reflectivity elucidate the main particle properties
  (optical thickness, size, imaginary refractive index) and their temporal
  evolution. The aerosol particles that formed during the impact have a
  mean radius of about 1 micron and are located high in the atmosphere
  (above 10 mbar), in good agreement ith ground-based observations in
  deep methane absorption bands in the near infrared. The density of
  this particle layer decreases with time until it approaches that of
  the pre-impact atmosphere. These results are also discussed in terms of
  what we know from other impacts in Jupiter (1994's SL9 event and 2010's
  bolide). Acknowledgements: SPH, ASL and RH are supported by the Spanish
  MICIIN AYA2009-10701 with FEDER and Grupos Gobierno Vasco IT-464-07.

---------------------------------------------------------
Title: Long-term Evolution of the Aerosol Debris Cloud Produced by
    the 2009 Impact of an Object with Jupiter
Authors: Sanchez-Lavega, Agustin; Orton, G. S.; Hueso, R.;
   Pérez-Hoyos, S.; Fletcher, L. N.; Garcia-Melendo, E.; Gomez,
   J. M.; de Pater, I.; Wong, M.; Hammel, H. B.; Yanamandra-Fisher, P.;
   Simon-Miller, M.; Barrado-Izagirre, N.; Marchis, F.; Mousis, O.; Ortiz,
   J. L.; Garcia, J.; Cecconi, M.; Clarke, J. T.; Noll, K.; Pedraz, S.;
   Wesley, A.; McConnel, N.; Kalas, P.; Graham, J.; McKenzie, L.; Reddy,
   V.; Golisch, W.; Griep, D.; Sears, P.; International Outer PLanet Watch
   (IOPW)
2010DPS....42.3101S    Altcode: 2010BAAS...42Q1009S
  We report the evolution of the cloud of aerosols produced in the
  atmosphere of Jupiter by the impact of an object in 19 July 2009
  (Sánchez-Lavega et al., Astrophys. J. Lett, Vol. 715, L155. 2010). This
  study is based on images obtained with a battery of ground-based
  telescopes and the Hubble Space Telescope in the visible and in
  the deep near infrared absorption bands at 2.1-2.3 microns from the
  impact date to 31 December 2009. The impact cloud expanded zonally
  from 5000 km (July 19) to 225,000 km (about 180 deg in longitude by
  29 October) and it was meridionally localized within a latitude band
  from -53.5 deg to -61.5 deg. During the first two months it showed a
  heterogeneous structure with embedded spots of a size of 500 - 1000
  km. The cloud was mainly dispersed in longitude by the dominant zonal
  winds and their meridional shear and, during the initial stages,
  by the action of local motions perhaps originated by the thermal
  perturbation produced at the impact site. The tracking of individual
  spots within the impact cloud showed that the winds increase their
  eastward velocity with altitude above the tropopause by 5-10 m/s. We
  found evidence of discrete localized meridional motions in the
  equatorward direction with speeds of 1 - 2 m/s. Measurements of the
  cloud reflectivity evolution during the whole period showed that it
  followed an exponential decrease with a characteristic time of 15 days,
  shorter than the 45 - 200 days sedimentation time for the small aerosol
  particles in the stratosphere. A radiative transfer model of the cloud
  optical depth coupled to an advection model of the cloud dispersion
  by the wind shears, reproduces this behavior. Acknowledgements: ASL,
  RH, SPH, NBI are supported by the Spanish MICIIN AYA2009-10701 with
  FEDER and Grupos Gobierno Vasco IT-464-07.

---------------------------------------------------------
Title: Seasonal and Temporal Changes on Jupiter and Saturn: A Review
    of Ground-based Observations
Authors: Yanamandra-Fisher, Padma A.; Orton, G. S.; Fisher, B. M.;
   Fletcher, L. N.; Miller, A. S.
2010DPS....42.1102Y    Altcode: 2010BAAS...42.1017Y
  We report on the seasonal and temporal changes observed on Jupiter and
  Saturn, based on near- and mid-infrared data acquired from several
  observatories (NASA/InfraRed Telescope Facility, NAOJ/Subaru,
  ESO/Very Large Telescope) and provide compelling rationale for a
  coordinated network of large telescopes for continued ground-based
  observations. Jupiter has been experiencing an era of atmospheric
  global upheaval since 2005, the observed atmospheric changes being
  manifestations of changes in local meteorology and latent physical
  parameters of the system, and occur on various timescales and
  latitudes. The discrete storms in Jupiter's atmosphere have undergone
  significant changes over the past decade. The merger of the three
  white ovals into Oval BA and its subsequent color change in 2006
  appear to be correlated to periodic interactions with the Great Red
  Spot (GRS). Subsequent episodes of GRS-Oval BA interactions in 2006
  and 2008 and the upcoming interaction in 2010 provide snapshots of
  changes in the local meteorology. We identify relationships between
  latent physical variables of the spatially and temporally changing
  systems in terms of cloud opacities, aerosol distribution and thermal
  fields. Ground-based near- and mid-infrared observations of Saturn from
  1995 - 2009, covering half a Saturnian year, provide a rich data set
  to model seasonal changes in Saturn's atmosphere from autumnal equinox
  (1995) to vernal equinox (2009). Since 1995, as Saturn's south pole
  received increasing solar insolation, its albedo exhibits an increase
  in reflectivity at mid-latitudes in the southern hemisphere, decreasing
  towards the equator, anti-correlated with the thermal field. Similar
  to equatorial oscillations of temperatures on Earth and Jupiter, Saturn
  displays stratospheric temperature oscillations, with a period of half
  a Saturnian year, suggesting the influence of seasonal forcing. We
  anticipate development of similar phenomena in the next few years,
  as Saturn approaches northern solstice.

---------------------------------------------------------
Title: Mid-IR Atmospheric Tracers of Jupiter's Storm Oval BA
Authors: Shannon, Matthew J.; Orton, G.; Fletcher, L.
2010DPS....42.1103S    Altcode: 2010BAAS...42R1017S
  The 2005-2006 reddening of a major anticyclonic storm, known as
  Oval BA, in Jupiter's turbulent atmosphere may well be a paradigm
  for the formation of red-colored vortices on the giant planets,
  including Jupiters Great Red Spot. Mid-infrared observations can be
  effectively used to determine physical and chemical properties of the
  atmosphere, and we present the results of mid-infrared thermal imaging
  observations, collected from NASAs Infrared Telescope Facility (IRTF)
  in Hawaii, ESOs Very Large Telescope (VLT) in Chile and the NAOJ Subaru
  Telescope in Hawaii between spring of 2005 and summer of 2006. These
  address the role of atmospheric tracers, including cloud opacity,
  the ammonia gas content, and the variation of the fraction of para-
  to ortho-hydrogen from local thermal equilibrium in assessing the rate
  of upwelling. These properties were retrieved with the Oxford-developed
  code, Nemesis, with the purpose of providing constraints on dynamical
  models in an effort to identify the mechanism for the color change. The
  most obvious change is that the temperature gradient from the inner to
  the outer part of Oval BA increased over the time of the color change,
  indicating a strengthening of the intensity of the vortex.

---------------------------------------------------------
Title: Saturn's "String of Pearls” After Five Years: Still There,
    Moving Backwards Faster in the Voyager System
Authors: Baines, Kevin H.; Momary, T. W.; Fletcher, L. N.; Buratti,
   B. J.; Brown, R. H.; Clark, R. N.; Nicholson, P. D.
2010DPS....42.4103B    Altcode: 2010BAAS...42.1039B
  Since July 2005, the Visual Infrared Mapping Spectrometer (VIMS) onboard
  the Cassini Orbiter has been following an enigmatic feature centered
  at 33.9 degrees (planetocentric ) north latitude. Observed in detail on
  14 occasions between July 2005 and July 2010, the feature is seen only
  in the 5-micron thermal window which probes large-particle clouds down
  to the ∼ 4-bar level. This feature is comprised of a main cloud layer
  near 1.5-3 bar which has 21-25 regularly spaced, near- uniformly-sized,
  circularly-shaped clearings which together span, on average, 94 degrees
  of longitude. In VIMS 5-micron imagery, which observes the warm glow of
  Saturn generated at depth, these regularly spaced and shaped clearings
  appear bright while the surrounding cloud, observed in silhouette,
  appears dark- hence the colloquial name "String of Pearls". Each
  clearing is about 1 degree of longitude (∼900 km) wide, and is,
  on average over the five-years period, 4.3 degrees of longitude from
  its neighbor. In latitude, adjacent pearls are typically 0.4 degrees -
  or about 1 pearl radius - apart. At various times over the past five
  years of observations, the longitudinal length has varied from 76 to 104
  degrees and the mean separation between clearings has varied from 3.6 to
  5.0 degrees, while the mean latitude of the structure has ranged from
  32.9 to 34.8 degrees - or by 2 mean diameters of the pearls. The pearl
  structure moves retrograde in the Voyager system (Desch and Kaiser,
  Geophys. Res. Lett 8, 253-256, 1981) with an average speed over five
  years of 21.84 ± 0.02 m/s. Since late 2007, the mean latitude increased
  from 34.0 ± 0.2 to 34.5 ± 0.2 deg as the retrograde speed increased
  from 21.73 ± 0.09 m/s to 22.02 ± 0.08 m/s, making it the fastest
  moving retrograde feature observed by Cassini/VIMS in non-polar regions.

---------------------------------------------------------
Title: Saturn's Equatorial Plumes after Five Years: Still Lurking
    under the Haze
Authors: Momary, Thomas W.; Baines, K. H.; Fletcher, L. N.; Buratti,
   B. J.; Brown, R. H.; Clark, R. N.; Nicholson, P. D.
2010DPS....42.1119M    Altcode: 2010BAAS...42.1021M
  Numerous large, discrete cloud features have been observed for five
  years underneath Saturn's equatorial haze. They were clearly observed on
  three occasions - June 28, 2005, April 21, 2006 and May 1, 2010 - from a
  vantage point directly over the knife-edge of the rings, which reduced
  the ring obscuration of the disk to just ± 1 degrees of latitude
  centered at the equator. These features are seen only in the 5-micron
  thermal window which probes large-particle clouds down to the ∼ 4-bar
  level. In VIMS 5-micron imagery, which observes the warm glow of Saturn
  generated at depth, these deep clouds are observed in silhouette,
  appearing as dark features against the background glow. Spectral
  modeling indicates that they are primarily located in the 2-3 bar
  region. However, smaller particles of ammonia may be present overhead
  as a relatively small component of the 5-micron extinction. Indeed,
  the correlation of these features with the exceedingly high and thick
  equatorial haze layer indicates a plausible link: That these features
  involve vertical transport of gaseous condensibles to the upper
  troposphere forming the thick haze that is observed in images taken
  in reflected sunlight. The features are concentrated in two narrow,
  symmetrical cloudy zones between 4 and 8 degrees planetocentric latitude
  in both hemispheres, where they cover significant fractions, although
  varying, amounts of the total area of these latitudinal bands: ∼ 55%
  in 2005-2006 vs ∼ 28% in 2010. The mean area of the average feature
  was roughly constant over all three observations, with the longitudinal
  extent of the average feature in 2005-2006 decreasing ∼10% from 8
  degrees ( 8000 km) to 7.1 degrees in 2010 while the mean latitudinal
  extent increased by ∼10% from 3.05 in 2005 vs 3.4 degrees in 2010.

---------------------------------------------------------
Title: Solar Flares and the Chromosphere: A white paper for the
    Decadal Survey
Authors: Hudson, H. S.; Fletcher, L.; Turkmani, R.; Hawley, S. L.;
   Kowalski, A. F.; Berlicki, A.; Heinzel, P.
2010helio2010....1H    Altcode:
  No abstract at ADS

---------------------------------------------------------
Title: The Physical Structure and Chemical Composition of Neptune's
    Atmosphere from Combined Herschel and Spitzer Spectral Observations
Authors: Orton, Glenn S.; Moreno, R.; Lellouch, E.; Fletcher, L. N.;
   Hartogh, P.; Feuchtgruber, H.; Jarchow, C.; Cavalie, T.; Lara, L.;
   Rengel, M.; Gonzalez, A.; Line, M.; Herschel HssO Key Project Team
2010DPS....42.4409O    Altcode: 2010BAAS...42.1047O
  We report the analysis of thermal-infrared observations of Neptune's
  disk by experiments on the Spitzer and Herschel Space Telescopes. The
  Spitzer data were obtained by the IRS instrument at wavelengths
  between 5.2 and 21.5 microns at a spectral resolving power, R
  70, and at wavelengths between 10 and 21.5 microns at R 600. The
  Herschel observations were made by the PACS instrument's integral
  field spectrometer between 51 and 220 microns at R 3000, within the
  framework of the Key Project, “Water and Related Chemistry in the
  Solar System”. Our analysis is set in the context of lower-resolution
  spectra obtained by the ISO LWS and SWS spectrometers covering
  wavelengths between 28 and 185 microns and the Akari IRC spectrometer
  covering wavelengths between 5.8 and 13.3 microns at R 40, together
  with spatially resolved ground-based studies of thermal emission. Our
  results indicate that that global-mean tropospheric temperatures are
  lower than those derived from the Voyager radio-occultation experiment,
  and consistent with the ISO results. Preliminary results (Lellouch
  et al. 2010 Astron. &amp; Astrophys. In press) indicate that the D/H
  ratio is 4.5±1.0 x 10<SUP>-5</SUP>, consistent with enrichment of
  deuterium over the protosolar value, and the stratospheric column of
  H<SUB>2</SUB>O is 2.1±0.5 x 10<SUP>14</SUP> cm<SUP>-2</SUP>. The
  peak CH<SUB>4</SUB> abundance in the stratosphere is orders of
  magnitude larger than if it were cold-trapped below the mean 54-Kelvin
  tropopause minimum temperature - but consistent with injection from
  Neptune's warmer south polar region. Good fits to a variety of other
  stratospheric emission features are obtained: CO, CH<SUB>3</SUB>,
  CO<SUB>2</SUB>, C<SUB>2</SUB>H<SUB>2</SUB>, C<SUB>2</SUB>H<SUB>4</SUB>,
  C<SUB>2</SUB>H<SUB>6</SUB>, C<SUB>3</SUB>H<SUB>8</SUB>,
  C<SUB>4</SUB>H<SUB>2</SUB>. It is also possible to obtain a better fit
  to a spectral region dominated by C<SUB>2</SUB>H<SUB>6</SUB> emission
  by adding 50-100 ppt of C<SUB>6</SUB>H<SUB>6</SUB>.

---------------------------------------------------------
Title: First Earth-based Detection of a Superbolide on Jupiter
Authors: Hueso, Ricardo; Wesley, A.; Go, C.; Perez-Hoyos, S.; Wong,
   M. H.; Fletcher, L. N.; Sanchez-Lavega, A.; Boslough, M. B. E.;
   de Pater, I.; Orton, G. S.; Simon-Miller, A. A.; Djorgovski,
   S. G.; Edwards, M. L.; Hammel, H. B.; Clarke, J. T.; Noll, K. S.;
   Yanamandra-Fisher, P. A.
2010DPS....42.3102H    Altcode: 2010BAAS...42.1009H
  On June 3, 2010 a bolide in Jupiter's atmosphere was observed from the
  Earth for the first time. The flash was detected by amateur astronomers
  A. Wesley and C. Go observing in two wavelength ranges. We present an
  analysis of the light curve of those observations that allow estimating
  the size of the object to be significantly smaller than the SL9 and
  the July 2009 Jupiter impact. Observations obtained a few days later
  by large telescopes including HST, VLT, Keck and Gemini showed no
  signature of the impact in Jupiter atmosphere confirming the small
  size of the impact body. A nearly continuous observation campaign
  based on several small telescopes by amateurs astronomers might allow
  an empirical determination of the flux of meteoroids in Jupiter with
  implications for the populations of small bodies in the outer solar
  system and may allow a better quantification of the threat of impacting
  bodies to Earth. <P />Acknowledgements: RH, ASL and SPH are supported
  by the Spanish MICIIN AYA2009-10701 with FEDER and Grupos Gobierno
  Vasco IT-464-07. LNF is supported by a Glasstone Science Fellowship
  at the University of Oxford.

---------------------------------------------------------
Title: Thermal Imaging of Jupiter's Giaht Vortices: the Great Red
    Spot and Oval BA
Authors: Orton, G.; Fletcher, L.; Yanamandra-Fisher, P.; Mousis,
   O.; Fisher, B.; Irwin, P.; Vanzi, L.; Fujiyoshi, T.; Fuse, T.;
   Simon-Miller, A.
2010epsc.conf..674O    Altcode:
  No abstract at ADS

---------------------------------------------------------
Title: Recovery of Neptune's Near-Polar Stratospheric Hot Spot
Authors: Orton, G.; Fletcher, L.; Yanamandra-Fisher, P.; Encrenaz,
   T.; Leyrat, C.; Hammel, H.
2010epsc.conf..678O    Altcode:
  No abstract at ADS

---------------------------------------------------------
Title: Jupiter 2010: A Busy Year
Authors: Go, C. Y.; Wesley, A.; Wong, M.; de Pater, I.; Sanchez-Lavega,
   A.; Marcus, P.; Huesco, R.; Rogers, J.; Simon-Miller, A.; Orton,
   G. S.; Yanamandra-Fisher, P.; Fletcher, L.
2010epsc.conf..915G    Altcode:
  No abstract at ADS

---------------------------------------------------------
Title: Potential for stratospheric Doppler windspeed measurements
    of Jupiter by sub-millimetre spectroscopy
Authors: Hurley, J.; Irwin, P. G. J.; Ellison, B. N.; de Kok, R.;
   Calcutt, S. B.; Teanby, N. A.; Fletcher, L. N.; Irshad, R.
2010P&SS...58.1489H    Altcode:
  The sub-millimetre/microwave range of the spectrum has been exploited
  in the field of Earth observation by many instruments over the years
  and has provided a plethora of information on atmospheric chemistry and
  dynamics - however, this spectral range has not been fully explored
  in planetary science, having been exclusively employed to carry out
  ground-based measurements. To this end, a sub-millimetre instrument,
  the Orbiter Terahertz Infrared Spectrometer (ORTIS), is studied by
  the University of Oxford and the Rutherford Appleton Laboratory, to
  meet the requirements of the European Space Agency's Cosmic Visions
  2015-2025 programme - in particular, the Europa Jupiter System Mission
  (EJSM), which has the European Space Agency and the National Aeronautics
  and Space Administration as partners. ORTIS is designed to measure
  atmospheric temperature, the abundance of stratospheric water vapour and
  other jovian gases, and is intended to be capable of retrieving vertical
  profiles of horizontal windspeed in the stratosphere for the first
  time, from Doppler-shifted emission lines measured at high spectral
  resolution. In this work, a preliminary study and implementation of the
  estimation of windspeed profiles on simulated spectra representative
  of Jupiter is presented, detailing the development of the retrieval
  algorithm, showing that a sub-millimetre instrument such as ORTIS should
  be able to retrieve windspeed profiles to an accuracy of about 15 m/s
  between 70 and 200 km/0.1-10 mb using a single near-limb measurement,
  for expected noise amplitudes.

---------------------------------------------------------
Title: From Large-scale Loops to the Sites of Dense Flaring Loops:
    Preferential Conditions for Long-period Pulsations in Solar Flares
Authors: Foullon, C.; Fletcher, L.; Hannah, I. G.; Verwichte, E.;
   Cecconi, B.; Nakariakov, V. M.; Phillips, K. J. H.; Tan, B. L.
2010ApJ...719..151F    Altcode:
  Long-period quasi-periodic pulsations (QPPs) of solar flares are
  a class apart from shorter period events. By involving an external
  resonator, the mechanism they call upon differs from traditional QPP
  models, but has wider applications. We present a multi-wavelength
  analysis of spatially resolved QPPs, with periods around 10 minutes,
  observed in the X-ray spectrum primarily at energies between 3 and 25
  keV. Complementary observations obtained in Hα and radio emission in
  the kHz to GHz frequency range, together with an analysis of the X-ray
  plasma properties provide a comprehensive picture that is consistent
  with a dense flaring loop subject to periodic energization and
  thermalization. The QPPs obtained in Hα and type III radio bursts,
  with similar periods as the QPPs in soft X-rays, have the longest
  periods ever reported for those types of data sets. We also report 1-2
  GHz radio emission, concurrent with but unrestricted to the QPP time
  intervals, which is multi-structured at regularly separated narrowband
  frequencies and modulated with ~18 minute periods. This radio emission
  can be attributed to the presence of multiple "quiet" large-scale loops
  in the background corona. Large scale but shorter inner loops below
  may act as preferential resonators for the QPPs. The observations
  support interpretations consistent with both inner and outer loops
  subject to fast kink magnetohydrodynamic waves. Finally, X-ray imaging
  indicates the presence of double coronal sources in the flaring sites,
  which could be the particular signatures of the magnetically linked
  inner loops. We discuss the preferential conditions and the driving
  mechanisms causing the repeated flaring.

---------------------------------------------------------
Title: Lepton models for TeV emission from SNR RX J1713.7-3946
Authors: Fan, Z. H.; Liu, S. M.; Yuan, Q.; Fletcher, L.
2010A&A...517L...4F    Altcode: 2010arXiv1007.0796F
  <BR /> Aims: SNR RX J1713.7-3946 is perhaps one of the best observed
  shell-type supernova remnants with emissions dominated by energetic
  particles accelerated near the shock front. The nature of the TeV
  emission, however, is an issue still open to investigation. <BR />
  Methods: We carried out a systematic study of four lepton models for the
  TeV emission with the Markov chain Monte Carlo method. <BR /> Results:
  It is shown that current data already give good constraints on the model
  parameters. Two commonly used parametric models do not appear to fit the
  observed radio, X-ray, and γ-ray spectra. Models motivated by diffusive
  shock acceleration and by stochastic acceleration by compressive waves
  in the shock downstream give comparably good fits. The former has a
  sharper spectral cutoff in the hard X-ray band than the latter. Future
  observations with the HXMT and NuSTAR may distinguish these two models.

---------------------------------------------------------
Title: OT1_lfletche_1: Nitrogen, Phosphorus and Sulphur Chemistry in
Saturn's Atmosphere: Internal and External Origins for HCN, HCP and CS
Authors: Fletcher, L. N.
2010hers.prop..978F    Altcode:
  Our understanding of some of the fundamental physiochemical processes
  at work within Saturns gaseous atmosphere is presently limited by
  the difficulties associated with detection of a number of atmospheric
  species. Based on our new understanding of Saturns bulk composition
  and chemistry from the Cassini mission, Herschel/HIFI offers an
  unprecedented opportunity to detect these species for the first
  time, and to place constraints on their origins. Radiative transfer
  calculations have been used in tandem with chemical modelling to
  select optimal transitions of HCN, HCP and CS for study by HIFI. These
  species have never been detected before, but are expected to be
  important secondary repositories for nitrogen, phosphorus and sulphur
  in Saturns atmosphere. Furthermore, the superb spectral resolution
  of heterodyne spectroscopy is ideal for distinguishing between broad
  tropospheric absorptions and narrow stratospheric emissions, allowing
  us to distinguish between internal and external origins for each
  species. Tropospheric abundances will be compared to expectations from
  state of the art thermochemical and photochemical models, in addition
  to predictions of lightning-induced shock chemistry. Stratospheric
  abundances will be interpreted in terms of external supply of N,
  P and S-bearing materials, either from large asteroidal/cometary
  impacts (where shock chemistry in impact plumes is also important) or
  influx of material from Enceladus, the rings or interplanetary dust
  particles. As a result, the HIFI search for the first signatures of
  Saturns HCN, HCP and CS abundances will serve as vital constraints on
  internal chemistry and the coupling between Saturns cold atmosphere
  and external environment, revealing the fundamental processes at work
  in the cold outer reaches of our Solar System.

---------------------------------------------------------
Title: Jupiter After the 2009 Impact: Hubble Space Telescope Imaging
    of the Impact-generated Debris and its Temporal Evolution
Authors: Hammel, H. B.; Wong, M. H.; Clarke, J. T.; de Pater, I.;
   Fletcher, L. N.; Hueso, R.; Noll, K.; Orton, G. S.; Pérez-Hoyos,
   S.; Sánchez-Lavega, A.; Simon-Miller, A. A.; Yanamandra-Fisher, P. A.
2010ApJ...715L.150H    Altcode:
  We report Hubble Space Telescope images of Jupiter during the aftermath
  of an impact by an unknown object in 2009 July. The 2009 impact-created
  debris field evolved more slowly than those created in 1994 by the
  collision of the tidally disrupted comet D/Shoemaker-Levy 9 (SL9). The
  slower evolution, in conjunction with the isolated nature of this
  single impact, permits a more detailed assessment of the altitudes and
  meridional motion of the debris than was possible with SL9. The color
  of the 2009 debris was markedly similar to that seen in 1994, thus this
  dark debris is likely to be Jovian material that is highly thermally
  processed. The 2009 impact site differed from the 1994 SL9 sites in UV
  morphology and contrast lifetime; both are suggestive of the impacting
  body being asteroidal rather than cometary. Transport of the 2009
  Jovian debris as imaged by Hubble shared similarities with transport
  of volcanic aerosols in Earth's atmosphere after major eruptions.

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Title: The Impact of a Large Object on Jupiter in 2009 July
Authors: Sánchez-Lavega, A.; Wesley, A.; Orton, G.; Hueso, R.;
   Perez-Hoyos, S.; Fletcher, L. N.; Yanamandra-Fisher, P.; Legarreta,
   J.; de Pater, I.; Hammel, H.; Simon-Miller, A.; Gomez-Forrellad,
   J. M.; Ortiz, J. L.; García-Melendo, E.; Puetter, R. C.; Chodas, P.
2010ApJ...715L.155S    Altcode: 2010arXiv1005.2312S
  On 2009 July 19, we observed a single, large impact on Jupiter at
  a planetocentric latitude of 55°S. This and the Shoemaker-Levy
  9 (SL9) impacts on Jupiter in 1994 are the only planetary-scale
  impacts ever observed. The 2009 impact had an entry trajectory in
  the opposite direction and with a lower incidence angle than that
  of SL9. Comparison of the initial aerosol cloud debris properties,
  spanning 4800 km east-west and 2500 km north-south, with those produced
  by the SL9 fragments and dynamical calculations of pre-impact orbit
  indicates that the impactor was most probably an icy body with a size
  of 0.5-1 km. The collision rate of events of this magnitude may be
  five to ten times more frequent than previously thought. The search for
  unpredicted impacts, such as the current one, could be best performed
  in 890 nm and K (2.03-2.36 μm) filters in strong gaseous absorption,
  where the high-altitude aerosols are more reflective than Jupiter's
  primary clouds.

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Title: The Impact of a Large Object with Jupiter in July 2009
Authors: Sanchez-Lavega, Agustin; Wesley, A.; Orton, G.; Chodas,
   P.; Hueso, R.; Perez-Hoyos, S.; Fletcher, L.; Yanamandra-Fisher, P.;
   Legarreta, J.; Gomez-Forrellad, J. M.
2010EGUGA..1215311S    Altcode:
  The only major impact ever observed directly in the Solar System
  was that of a large fragmented comet with Jupiter in July (1994)
  (Comet Shoemaker-Levy 9; SL9). We report here the observation of a
  second, single, large impact on Jupiter that occurred on 19 July
  2009 at a latitude of -55° with an orthogonal entry trajectory
  and a lower incidence angle compared to those of SL9. The size of
  the initial aerosol cloud debris was 4,800 km East-West and 2,500 km
  North-South. Comparison its properties with those produced by the SL9
  fragments, coupled with dynamical calculations of possible pre-impact
  orbits, indicates that the impactor was most probably an icy body
  with a size of 0.5-1 km. We calculate that the rate of collisions of
  this magnitude may be five to ten times more frequent than previously
  thought. The search for unpredicted impacts, such as the current one,
  could be best performed in the near-infrared methane absorption bands
  at 890 nm and in the 2.12 to 2.3 μm K methane-hydrogen absorption
  band, where the high-altitude aerosols detach by their brightness
  relative to Jupiter's primary clouds. We present measurements of the
  debris dispersion by Jovian winds from a long-term imaging campaign
  with ground-based telescopes. Ackowledgements: Work was supported by
  the Spanish MICIIN AYA2009-10701 with FEDER and Grupos Gobierno Vasco
  IT-464-07, by NASA funds to JPL, Caltech, by the NASA Postdoctoral
  Program at JPL, and by the Glasstone Fellowship program at Oxford.

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Title: Radio Observations And Modeling Of A Post-flare Arcade
Authors: Bain, Hazel; Fletcher, L.
2010AAS...21632105B    Altcode: 2010BAAS...41..912B
  We present observations of a flaring arcade which was observed by
  RHESSI, TRACE and the Nobeyama Radioheliograph (NoRH). The event
  occurred on the west limb of the Sun and whilst EUV observations reveal
  an arcade structure, the radio emission appears as a single loop. NoRH
  observations at 17 GHz and 34 GHz show that the spatial distribution
  of brightness varies along the loop and the relative brightness of
  looptop and footpoint sources varies over time. We concentrate our
  investigation on the decay phase of the flare and using estimates of
  relevant plasma parameters obtained from observations, we attempt to
  reproduce the observed radio emission. We compare the gyrosynchrotron
  emission from both a simple dipole and an arcade magnetic field
  model to investigate line of sight enhancements from optically thin
  plasma. Using a continuous thermal/nonthermal electron distribution
  we investigate the contribution from hot thermal plasma. This work
  was funded by an STFC studentship.

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Title: Neptune's atmospheric composition from AKARI infrared
    spectroscopy
Authors: Fletcher, L. N.; Drossart, P.; Burgdorf, M.; Orton, G. S.;
   Encrenaz, T.
2010A&A...514A..17F    Altcode: 2010arXiv1003.5571F
  <BR /> Aims: Disk-averaged infrared spectra of Neptune between 1.8 and
  13 μm, obtained by the AKARI infrared camera (IRC) in May 2007, have
  been analysed to (a) determine the globally-averaged stratospheric
  temperature structure; (b) derive the abundances of stratospheric
  hydrocarbons; and (c) detect fluorescent emission from CO at 4.7
  μm. <BR /> Methods: Mid-infrared spectra (SG1 and SG2 channels of
  AKARI/IRC), with spectral resolutions of 47 and 34 respectively, were
  modelled using a line-by-line radiative transfer code to determine
  the temperature structure between 1-1000 μbar and the abundances
  of CH<SUB>4</SUB>, CH<SUB>3</SUB>D and higher-order hydrocarbons. A
  full non-LTE radiative model was then used to determine the best
  fitting CO profile to reproduce the fluorescent emission observed at
  4.7 μm in the NG channel (with a spectral resolution of 135). <BR />
  Results: The globally-averaged stratospheric temperature structure is
  quasi-isothermal between 1-1000 μbar, which suggests little variation
  in global stratospheric conditions since studies by the Infrared
  Space Observatory a decade earlier. The derived CH<SUB>4</SUB> mole
  fraction of (9.0 ± 3.0)× 10<SUP>-4</SUP> at 50 mbar, decreasing
  to (0.9 ± 0.3)× 10<SUP>-4</SUP> at 1 μbar, is larger than that
  expected if the tropopause at 56 K acts as an efficient cold trap,
  but consistent with the hypothesis that CH<SUB>4</SUB> leaking through
  the warm south polar tropopause (62-66 K) is globally redistributed by
  stratospheric motion. The ratio of D/H in CH<SUB>4</SUB> of 3.0 ± 1.0
  × 10<SUP>-4</SUP> supports the conclusion that Neptune is enriched
  in deuterium relative to the other giant planets. We determine a mole
  fraction of ethane of (8.5 ± 2.1)× 10<SUP>-7</SUP> at 0.3 mbar,
  consistent with previous studies, and a mole fraction of ethylene of
  5.0<SUB>-2.1</SUB><SUP>+1.8</SUP> × 10<SUP>-7</SUP> at 2.8 μbar. An
  emission peak at 4.7 μm is interpreted as a fluorescent emission of CO,
  and requires a vertical distribution with both external and internal
  sources of CO. Finally, comparisons to previous L-band studies indicate
  significant variability of Neptune's flux densities in the 3.5-4.1
  μm range, related to changes in solar energy deposition.

---------------------------------------------------------
Title: Using Active Contours for Semi-Automated Tracking of UV and
    EUV Solar Flare Ribbons
Authors: Gill, C. D.; Fletcher, L.; Marshall, S.
2010SoPh..262..355G    Altcode: 2010SoPh..tmp...20G
  Solar-flare UV and EUV images show elongated bright "ribbons" that
  move over time. If these ribbons are assumed to locate the footpoints
  of magnetic-field lines reconnecting in the corona, then it is clear
  that studying their evolution can provide important insight into
  the reconnection process. An image-processing method based on active
  contours (commonly referred to as "snakes") is proposed as a method
  for tracking UV and EUV flare ribbons and is tested on images from the
  Transition Region and Coronal Explorer (TRACE). This paper introduces
  the basic concepts of such an approach with a brief overview of the
  history and theory behind active contours. It then details the specifics
  of the snake algorithm developed for this work and shows the results of
  running the algorithm on test images. The results from the application
  of the developed algorithm are reported for six different TRACE flares
  (five in UV and one in EUV). The discussion of these results uses the
  output from an expert tracking the same ribbons by eye as a benchmark,
  and against these the snake algorithm is shown to compare favourably
  in certain conditions, but less so in others. The applicability of the
  automated snake algorithm to the general problem of ribbon tracking
  is discussed and suggestions for ways to improve the snake algorithm
  are proposed.

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Title: Possible liquid water origin for Atacama Desert mudflow and
    recent gully deposits on Mars
Authors: Heldmann, J. L.; Conley, C. A.; Brown, A. J.; Fletcher, L.;
   Bishop, J. L.; McKay, C. P.
2010Icar..206..685H    Altcode:
  Evidence of recent gully activity on Mars has been reported based on the
  formation of new light toned deposits within the past decade, the origin
  of which remains controversial. Analogous recent light toned gully
  features have formed by liquid water activity in the Atacama Desert
  on Earth. These terrestrial deposits leave no mineralogical trace of
  water activity but rather show an albedo difference due to particle size
  sorting within a fine-grained mudflow. Therefore, spectral differences
  indicating varying mineralogy between a recent gully deposit and the
  surrounding terrain may not be the most relevant criteria for detecting
  water flow in arid environments. Instead, variation in particle size
  between the deposit and surrounding terrain is a possible discriminator
  to identify a water-based flow. We show that the Atacama deposit is
  similar to the observed Mars gully deposits, and both are consistent
  with liquid water activity. The light-toned Mars gully deposits could
  have formed from dry debris flows, but a liquid water origin cannot be
  ruled out because not all liquid water flows leave hydrated minerals
  behind on the surface. Therefore, the Mars deposits could be remnant
  mudflows that formed on Mars within the last decade.

---------------------------------------------------------
Title: Silica Debris Star Systems — Spitzer Evidence for Lunar
    Formation Events &amp; Crustal Stripping or Magma Oceans &amp;
    Late Heavy Bombardments?
Authors: Lisse, C. M.; Chen, C. H.; Wyatt, M. C.; Morlok, A.; Thebault,
   P.; Orton, G. S.; Fletcher, L. N.; Fujiwara, H.; Bridges, J. C.;
   Elkins-Tanton, L. T.; Gaidos, E. J.; Trang, D.
2010LPI....41.2390L    Altcode:
  Recent work (Lisse et al., 2009) has detected amorphous silica and
  SiO gas around 12-m.y.-old HD172555, at the right age to form rocky
  planets. Here we discuss the location, lifetime, and source of the
  material, using inferences gleaned from HD172555 and three new silica
  systems.

---------------------------------------------------------
Title: The white-light continuum in the impulsive phase of a solar
    flare.
Authors: Hudson, H. S.; Fletcher, L.; Krucker, S.
2010MmSAI..81..637H    Altcode: 2010arXiv1001.1005H
  We discuss the IR/visible/VUV continuum emission of the impulsive
  phase of a solar flare, using TRACE UV and EUV images to characterize
  the spectral energy distribution. This continuum has been poorly
  observed but energetically dominates the radiant energy output
  . Recent bolometric observations of solar flares furthermore point to
  the impulsive phase as the source of a major fraction of the radiant
  energy. This component appears to exhibit a Balmer jump and thus must
  originate in an optically thin region above the quiet photosphere,
  with an elevated temperature and strong ionization.

---------------------------------------------------------
Title: The chromosphere during solar flares .
Authors: Fletcher, L.
2010MmSAI..81..616F    Altcode: 2010arXiv1001.0739F
  The emphasis of observational and theoretical flare studies in the
  last decade or two has been on the flare corona, and attention
  has shifted substantially away from the flare's chromospheric
  aspects. However, although the pre-flare energy is stored in the
  corona, the radiative flare is primarily a chromospheric phenomenon,
  and its chromospheric emission presents a wealth of diagnostics for
  the thermal and non-thermal components of the flare. I will here review
  the chromospheric signatures of flare energy release and the problems
  thrown up by the application of these diagnostics in the context of
  the standard flare model. I will present some ideas about the transport
  of energy to the chromosphere by other means, and calculations of the
  electron acceleration that one might expect in one such model.

---------------------------------------------------------
Title: Integrated Ly-alpha  intensity emission in ribbon flares
Authors: Rubio da Costa, F.; Fletcher, L.; Labrosse, N.; Zuccarello, F.
2010MSAIS..14..193R    Altcode:
  We have analyzed two flares observed by TRACE in Ly alpha (on 8th
  September 1999 and 28th February 1999) in order to deduce their
  morphology, temporal evolution, radiative outputs and compare these
  results with data obtained in the X-range (SXT and HXT on Yohkoh) and
  with magnetograms (MDI/SOHO). These observational data and the results
  obtained by a theoretical study of the intensity of the radiation
  emitted by hydrogen lines, contribute to construct semi-empirical and
  theoretical models of the chromospheric emission during flares. Future
  observations by the planned Extreme Ultraviolet Imager selected for
  the Solar Orbiter mission -which will have a Lyman alpha channel-
  and this work, can help in designing observational flare studies.

---------------------------------------------------------
Title: Hubble Imaging of Jupiter after the 2009 Impact
Authors: Hammel, Heidi B.; Clarke, J. T.; de Pater, I.; Fletcher,
   L. N.; Hueso, R.; Noll, K. S.; Orton, G. S.; Perez-Hoyos,
   S.; Sanchez-Lavega, A.; Simon-Miller, A. A.; Wong, M. H.;
   Yanamandra-Fisher, P. A.
2010AAS...21533407H    Altcode: 2010BAAS...42..434H
  On 19 July 2009, amateur astronomer Anthony Wesley discovered an
  anomalous dark feature near Jupiter's south pole (planetographic
  latitude -58° system III west longitude 305°). Additional observations
  confirmed the new feature was an impact site created by an unknown
  object (the only other observed collision with Jupiter occurred 15 years
  earlier, when the shattered remains of Comet Shoemaker-Levy 9 created
  huge atmospheric disturbances). A world-wide observing campaign was
  initiated in response to this 2009 collision. We were awarded Directors
  Discretionary Time to use the newly-installed Wide-Field Camera 3 (WFC3)
  on Hubble Space Telescope. Observations were successfully obtained
  with WFC3 on July 23, August 3, and August 8, and with the Advanced
  Camera for Surveys' Solar Blind Channel in the UV on September 8. In
  this talk, we will present a summary of the HST images. The evolution
  of the impact debris field at UV, visible, near-IR wavelengths will
  be discussed, along with a comparison to Hubble observations of the
  Shoemaker-Levy 9 impact in 1994.

---------------------------------------------------------
Title: Elementary Energy Release Events in Flaring Loops: Effects
    of Chromospheric Evaporation on X-Rays
Authors: Liu, Siming; Han, Feiran; Fletcher, Lyndsay
2010ApJ...709...58L    Altcode: 2009arXiv0912.0402L
  With the elementary energy release events introduced in a previous
  paper, we model the chromospheric evaporation in flaring loops. The
  thick-target hard X-ray (HXR) emission produced by electrons escaping
  from the acceleration region dominates the impulsive phase, and
  the thin-target emission from the acceleration region dominates the
  low-energy thermal component in the gradual phase, as observed in
  early impulsive flares. Quantitative details depend on properties of
  the thermal background, which leads to variations in the correlation
  between HXR flux and spectral index. For lower temperature and/or higher
  density of the background electrons, the HXRs both rise and decay more
  quickly with a plateau near the peak. The plateau is less prominent at
  higher energies. Given the complexity of transport of mass, momentum,
  and energy along loops in the impulsive phase, we propose a strategy
  to apply this single-zone energy release and electron acceleration
  model to observations of flares associated with single loops so that
  the energy release, electron acceleration, and evaporation processes
  may be studied quantitatively.

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Title: Non-LTE analysis of Uranus Observations from Spitzer
Authors: Zhang, X.; Martin-Torres, F.; Yung, Y. L.; Orton, G. S.;
   Fletcher, L. N.
2009AGUFM.P32C..01Z    Altcode:
  Spitzer Infrared Spectrometer (IRS) observations of the disk of
  Uranus between 5.2 and 32 microns (1920 cm-1-270 cm-1) contain a
  wealth of information about the its cold atmosphere. In particular,
  they enable the retrieval of temperature and the abundances of
  several gaseous species as a function of pressure. They can also
  be used to study the energetics of radiatively active species in
  regions of Uranus’ atmosphere where Local Thermodynamic Equilibrium
  (LTE) is expected to break down. Care must be taken in atmospheric
  sounding not to assume that the atmospheric compounds emit according
  to the Planck function at the local kinetic temperature. Many of the
  ro-vibrational states of atmospheric constituents responsible for
  infrared emissions have excitation temperatures that differ from the
  local kinetic temperature. While non-LTE emission has been extensively
  considered for remote sensing of the Earth, only one study by Appleby
  (Icarus, 85, p355-379, 1990), who examined the radiative equilibrium
  temperatures of methane (CH4) in the upper atmospheres of Jupiter,
  Saturn, Uranus, and Neptune, has estimated the influence of non-LTE
  effects in Uranus' upper atmosphere. Uranus is composed mainly of
  hydrogen and helium. Helium is radiatively inactive, and hydrogen is
  active only in its weak collision-induced absorption, and its quadrupole
  lines. At low pressures, non-LTE processes involve the quantum levels
  of the more abundant minor constituents become important. In the
  case of Uranus the most important gas in the latter category is CH4,
  which has a role rather analogous to that of carbon dioxide in the
  Earth’s atmosphere. Since the work by Appleby, the spectroscopic
  and kinetics information of methane and other hydrocarbons has
  greatly improved and computer capabilities allow avoiding previous
  simplifications. For example, the full coupling between CH4 v4 and the
  higher-energy vibrational states emitting/absorbing in the near-IR is
  now possible. In this presentation we analyze the non-LTE effects in
  Spitzer data using a new non-local thermodynamic equilibrium radiative
  transfer for the infrared emissions of CH4, C2H2, and C2H6 which are
  observed in its spectrum.

---------------------------------------------------------
Title: HST Observations of the July 2009 Impact on Jupiter
Authors: de Pater, I.; Hammel, H. B.; Simon-Miller, A. A.; Clarke,
   J. T.; Noll, K. S.; Orton, G. S.; Fletcher, L. N.; Yanamandra-Fisher,
   P. A.; Sanchez-Lavega, A.; Hueso, R.; Perez-Hoyos, S.; Wong, M. H.
2009AGUFM.P14D..01D    Altcode:
  On UT 19 July 2009 amateur astronomer Anthony Wesley announced that
  Jupiter might have been hit by an object, as evidenced from an anomalous
  feature near Jupiter’s south pole (at a southern planetgraphic
  latitude of 58 deg, and W. longitude III of 305 deg). A world-wide
  observing campaign was initiated in response, including Hubble Space
  Telescope Director Discretionary Time on the newly-installed WFC3
  camera. Observations were made on July 23, August 3 and 8. In this talk
  we will present a summary of the HST images at wavelengths between 400
  and 900 nm. In particular, we will compare the initial HST observations
  with contemporaneous data over a wide spectral range from the near-IR
  (Keck) and mid-IR (Gemini-North, VLT, Gemini-South). The evolution of
  the impact debris field at visible, near- and mid-IR wavelengths will
  be discussed, along with a comparison to the Shoemaker-Levy 9 impact
  in 1994.

---------------------------------------------------------
Title: A Mission Concept Study of a Dilute Aperture Visible Nulling
    Coronagraph Imager (DAViNCI) for the Detection and Spectroscopy
    of Exo-planets
Authors: Shao, Michael; Bairstow, S.; Deems, E.; Fletcher, L.; Levine,
   B.; Orton, G.; Vasisht, G.; Wayne, L.; Zhao, F.; Clampin, M.; Lyon,
   R.; Guyon, O.; Lane, B.; Havey, K.; Wynn, J.; Samuele, R.; Vasudevan,
   G.; Woodruff, R.; Tolls, V.; Malbet, F.; Leger, A.
2009AAS...21460603S    Altcode:
  DAViNCI is a mission concept for the imaging and spectroscopy
  of exo-planets from nearby stars. It is capable of surveying and
  characterizing over 100 stars at an inner working angle of 35mas
  at its maximum baseline. DAViNCI is a 4 aperture telescope imaging
  system separated by a variable baseline whose light is combined
  interfermometrically into a nulling coronagraph instrument coupled to an
  imaging camera and spectrometer. We will describe the science potential
  and configuration of DAViNCI, its architecture, its instruments, and the
  results of mission and instrument studies in terms of capability and
  cost. <P />This work was performed at the Jet Propulsion Laboratory,
  California Institute of Technology, under contract to the National
  Aeronautics and Space Administration.

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Title: Mapping potential vorticity dynamics on saturn: Zonal mean
    circulation from Cassini and Voyager data
Authors: Read, P. L.; Conrath, B. J.; Fletcher, L. N.; Gierasch,
   P. J.; Simon-Miller, A. A.; Zuchowski, L. C.
2009P&SS...57.1682R    Altcode:
  Maps of Ertel potential vorticity on isentropic surfaces (IPV) and
  quasi-geostrophic potential vorticity (QGPV) are well established in
  dynamical meteorology as powerful sources of insight into dynamical
  processes involving 'balanced' flow (i.e. geostrophic or similar). Here
  we derive maps of zonal mean IPV and QGPV in Saturn's upper troposphere
  and lower stratosphere by making use of a combination of velocity
  measurements, derived from the combined tracking of cloud features in
  images from the Voyager and Cassini missions, and thermal measurements
  from the Cassini Composite Infrared Spectrometer (CIRS) instrument. IPV
  and QGPV are mapped and compared for the entire globe between latitudes
  89<SUP>∘</SUP>S-82<SUP>∘</SUP>N. As on Jupiter, profiles of
  zonally averaged PV show evidence for a step-like "stair-case" pattern
  suggestive of local PV homogenisation, separated by strong PV gradients
  in association with eastward jets. The northward gradient of PV (IPV
  or QGPV) is found to change sign in several places in each hemisphere,
  however, even when baroclinic contributions are taken into account. The
  stability criterion with respect to Arnol'd's second stability theorem
  may be violated near the peaks of westward jets. Visible, near-IR and
  thermal-IR Cassini observations have shown that these regions exhibit
  many prominent, large-scale eddies and waves, e.g. including 'storm
  alley'. This suggests the possibility that at least some of these
  features originate from instabilities of the background zonal flow.

---------------------------------------------------------
Title: Thermal Evolution and Composition of the July 2009 Jupiter
    Impact Site from 7-25 Micron Imaging and Spectroscopy
Authors: Fletcher, L. N.; Orton, G. S.; Mousis, O.; de Pater,
   I.; Hammel, H. B.; Golisch, W.; Edwards, M.; Yanamandra-Fisher,
   P. A.; Fisher, B.; Greene, Z.; Lai, S.; Otto, E.; Reshetnikov, N.;
   Sanchez-Lavega, A.; Simon-Miller, A. A.; Hueso, R.; Perez-Hoyos, S.
2009AGUFM.P14D..03F    Altcode:
  We present analysis of thermal-infrared imaging and spectroscopy of
  the impact site near the south polar region of Jupiter (see Orton
  et al., AGU 2009). Enhanced thermal emission was first detected
  on July 20 2009 in 7-25 micron imaging from the MIRSI instrument
  on NASA’s IRTF. These observations, just two rotations after the
  impact, indicated the localised, high-temperature thermal signature
  of the ejecta field, coincident with the location of high-altitude
  particulate debris observed in the near-IR and visible. The impact
  feature was most visible in the 9-11 micron range, suggestive of
  enhanced emission from hydrocarbons and ammonia gas in the lower
  stratosphere. Subsequent thermal imaging of the impact region
  reveals the radiative cooling of the impact site and the changing
  morphology due to the redistribution of material by Jupiter’s zonal
  and meridional wind field. We acquired Gemini-N/Michelle imaging on
  July 22, Gemini-S/TReCS imaging on July 24 and August 5 and 9, and an
  extensive campaign of VLT/VISIR imaging on July 24, 26 and August 5, 10,
  15, 16, at which point (4 weeks after the impact) the thermal signature
  could no longer be reliably distinguished, even with sub-arcsecond
  diffraction-limited angular resolution. Tropospheric and stratospheric
  temperatures and aerosol opacity are derived via optimal estimation
  retrievals (Fletcher et al. 2009, Icarus, 200, p154). Enhancement
  of hydrocarbons and gaseous ammonia are determined via iterative
  forward modelling, aided by spectral observations obtained with the
  slit aligned east-west through the impact feature from Gemini-S/TReCS
  (July 24) and VLT/VISIR (July 26, August 12-13). Low-resolution N-band
  (8-13 microns) Gemini-S/TReCS spectra confirm the enhanced emission
  over a broad range of wavelengths; Q-band (17-25 micron) spectra are
  used to study upper tropospheric temperatures in the aftermath of
  the collision and the rate of radiative cooling. VLT/VISIR spectra
  provide higher spectral resolutions in narrow wavelength ranges near
  8.02, 10.49, 11.31, 11.60, 12.24 and 13.36 microns, sensitive to NH3,
  CH4 and hydrocarbon emission features. Iterative forward modelling of
  these spectra will be used to deduce the unique chemical composition and
  the three-dimensional thermal structure of the impact site, compared
  with the ‘unperturbed’ atmosphere at the same latitude. * Fletcher
  is supported by an appointment to the NASA Postdoctoral Program at
  the Jet Propulsion Laboratory/California Institute of Technology,
  administered by Oak Ridge Associated Universities through a contract
  with NASA. We wish to acknowledge the invaluable contributions of the
  support staff at IRTF, VLT and Gemini.

---------------------------------------------------------
Title: Hard X-ray emission from a flare-related jet
Authors: Bain, H. M.; Fletcher, L.
2009A&A...508.1443B    Altcode:
  Aims. We aim to understand the physical conditions in a jet event
  which occurred on the 22nd of August 2002, paying particular attention
  to evidence for non-thermal electrons in the jet material.<BR />
  Methods: We investigate the flare impulsive phase using multiwavelength
  observations from the Transition Region and Coronal Explorer (TRACE)
  and the Reuven Ramaty High Energy Spectroscopic Imager (RHESSI)
  satellite missions, and the ground-based Nobeyama Radioheliograph
  (NoRH) and Radio Polarimeters (NoRP).<BR /> Results: We report what we
  believe to be the first observation of hard X-ray emission formed in a
  coronal jet. We present radio observations which confirm the presence of
  non-thermal electrons present in the jet at this time. The evolution of
  the event is best compared with the magnetic reconnection jet model in
  which emerging magnetic field interacts with the pre-existing coronal
  field. We calculate an apparent jet velocity of ~500 km s<SUP>-1</SUP>
  which is consistent with model predictions for jet material accelerated
  by the J×B force resulting in a jet velocity of the order of the
  Alfvén speed (~100-1000 km s<SUP>-1</SUP>).<BR />

---------------------------------------------------------
Title: Emitted Power of Saturn Based on Cassini/CIRS Observations
Authors: Li, L.; Conrath, B. J.; Gierasch, P. J.; Achterberg, R. K.;
   Nixon, C. A.; Flasar, F. M.; Simon-Miller, A. A.; Fletcher, L. N.;
   Read, P. L.; Baines, K. H.; West, R. A.; Ingersoll, A. P.; Vasavada,
   A. R.; Orton, G. S.
2009AGUFM.P32C..03L    Altcode:
  We are evaluating the energy balance of Saturn through Cassini
  observations, utilizing in particular CIRS observations from 7 to
  500 micron and ISS/VIMS observations from 0.25 to 5.1 micron. The
  CIRS observations are utilized to compute the emitted power of Saturn
  between 2004 and 2009. Compared with the Voyagers' results, Cassini’s
  observations display significant variations in the global emitted
  power between the Voyager epoch (1979-1982) and the current Cassini
  time period (2004-2009). In addition, the meridional distribution of
  emitted power measured by Cassini shows that the emitted power is ~20%
  higher in the southern hemisphere than in the northern hemisphere. This
  is different from the Voyager results, which showed the two hemispheres
  to be roughly equal in emitted power. It is unclear whether the
  differences between the Voyager and Cassini epochs are due to the
  seasonal or inter-annual variations or both, but the time variations
  from 2004 to 2009 suggest that seasonal variations are at least part
  of the reason. The Cassini Equinox and Solstice Extended missions
  will continue to provide more knowledge of the seasonal/inter-annual
  variations of the emitted power. The computation of the reflected solar
  power by fitting Minnaert coefficient/Barkstrom model for each latitude
  bin or by directly utilizing the observed reflected radiance at each
  pixel of the globe is still in process. Combining the emitted power and
  the reflected solar power, we will estimate the energy balance of Saturn
  and its meridional distribution and seasonal/inter- annual variability.

---------------------------------------------------------
Title: Near-Infrared Spectroscopy and Imaging of the 2009 Jupiter
impact debris field: Constraints on particle composition, size and
    vertical distribution
Authors: Yanamandra-Fisher, P. A.; Orton, G. S.; Fletcher, L. N.;
   Fisher, B.; Greene, Z.; Otto, E.; Reshetnikov, N.; Golisch, W.;
   Lystrup, M. B.; Shara, M.; Moskovitz, N. A.; Trilling, D.; Reddy,
   V.; Rivkin, A.; Grundy, W. M.; Emery, J. P.; Kim, J.; Baines, K. H.;
   Griep, D.; Sears, P.
2009AGUFM.P31A1228Y    Altcode:
  We present results of near-infrared imaging and spectroscopy of the
  2009 Jupiter impact site and its associated debris field during the
  time period from 20 July 2009 (approximately 20 hours after impact) to
  31 August 2009 (nearly six weeks post-impact). Our data were acquired
  with NASA/InfraRed Telescope Facility (IRTF) facility instruments,
  SpeX, 1- to 5-micron spectrometer and its guide camera, and NSFCam2,
  1- to 5-micron multi-spectral camera. On 20 July, the impact site
  appeared as a localized region, close to and brighter than Jupiter's
  south polar haze. The impact site then expanded longitudinally in both
  directions. Nearly five weeks later, the debris field continues to
  spread, characterized by a few localized structures or cores near the
  original impact longitude, surrounded by material which is extended
  by about 7 degrees in latitude and 80 degrees in longitude. Early
  multi-spectral images and spectra of the debris identify ammonia as a
  constituent. Spectra and images of the debris material in subsequent
  weeks, redistributed by the zonal and meridional wind field of Jupiter,
  indicates the debris continues to be very prominent at 2 microns;
  comparable in reflectivity to the south polar haze and high in the
  atmosphere, implying small particles. The cores of the debris field were
  the only components of the neutral atmosphere detectable in the strong
  methane-absorbing 3.2- to 3.4-micron region as late as 6 August, but
  they were no longer detectable as of 18 August. In the 2-micron region,
  the debris reflectivity also diminished with time, mostly likely as a
  result of downward sedimentation. Our results will be compared to the
  those from SL9 fragment impacts and the "undisturbed" Jovian atmosphere,
  constraining the vertical distribution of the perturbation, composition
  and particle sizes of the debris.

---------------------------------------------------------
Title: Debris Field of the July 19, 2009, Impact in Jupiter and Its
    Long-term Evolution
Authors: Orton, G. S.; Wesley, A.; Mousis, O.; Fletcher, L. N.;
   Yanamandra-Fisher, P. A.; Fisher, B.; Simon-Miller, A. A.; Greene,
   Z. S.; de Pater, I.; Hammel, H. B.; Reshetnikov, N.; Otto, E.; Lai,
   S.; Rogers, J.; Sanchez-Lavega, A.; Perez-Hoyos, S.; Hueso, R.;
   Golisch, W.; Griep, D.; Sears, P.; Lystrup, M. B.; Shara, M.; Young,
   L.; Grundy, W. M.; Moskovitz, N. A.; Rivkin, A. S.; Reddy, V.; Emery,
   J. P.; Trilling, D.; Ziffer, J.
2009AGUFM.P14D..04O    Altcode:
  A multi-platform suite of imaging and spectroscopic observations of
  Jupiter's atmosphere tracked the evolution of the debris field of an
  unknown impactor on 2009 July 19. The initial debris field is similar
  to those of intermediate Shoemaker-Levy 9 fragments, suggesting a
  body hundreds of meters in size, if icy, entering from the west and
  slightly north. The field is detectable in the visible as dark material
  and in the near-IR by high-altitude particulate reflectivity; it was
  quickly redistributed by different zonal flows across its latitudinal
  range. At first, the particulate field was highly correlated with areas
  of enhanced temperatures and enhanced ammonia and ethane emission,
  but this was no longer true by mid-August. As of Sept. 2, the debris
  field was undetectable in the thermal, detectable in the visible with
  good seeing, and still prominent near 2 microns wavelength. Visibly,
  the impact "scar" consists of two dark regions along the same latitude,
  ostensibly different from the central bright region associated with
  the near-IR debris pattern. Both morphologies show eastern and western
  extensions propagating away from the original impact site, which appear
  to be influenced by flows around vortices previously undetected in
  Jupiter atmosphere. These observations define the flow field just
  north of Jupiter's southern polar vortex at higher altitudes than
  tracked in Jupiter's main cloud deck.

---------------------------------------------------------
Title: Thermal and Near-Infrared Structural Evolution of the 2009
    Wesley Jupiter Impact from 1.5-24.5 Micron Imaging
Authors: Greene, Z. S.; Orton, G. S.; Fletcher, L. N.;
   Yanamandra-Fisher, P. A.; Mousis, O.; Fisher, B.; Reshetnikov, N.;
   Lai, S.; Otto, E.; Hammel, H. B.; de Pater, I.; Edwards, M.
2009AGUFM.P33B1282G    Altcode:
  We show the morphological evolution of the remnant scar from the Jupiter
  impact (July 19, 2009) at mid- and near-infrared wavelengths. Data
  taken less than 24 hours after the impact using NASA’s IRTF capture
  the initial structure at a wide range of wavelengths from 1.5-24.5
  microns. Furthermore, images obtained from NASA’s Infrared Telescope
  Facility, Gemini North and South, and the Very Large Telescope in
  the subsequent weeks allow us to monitor the evolving morphology of
  the feature as zonal and meridional winds redistributed the impact
  debris through Jupiter’s atmosphere. Our observations indicate
  that the feature expanded primarily in the longitudinal direction
  in both the mid- and near-infrared, but underwent separation in
  the latitudinal direction much earlier in the thermal. The impact
  feature also became indistinguishable from its Jovian background in
  the thermal as of mid-August, whereas the scar remains distinct in the
  near-infrared. Timelines and images at various thermal and near-infrared
  wavelengths will be used to show the rapid evolution of the debris from
  July 20 to late August. *This work was performed at the Jet Propulsion
  Laboratory, California Institute of Technology, sponsored by the Summer
  Undergraduate Research Fellowship (SURF) program.

---------------------------------------------------------
Title: Modelling the Longitudinal Asymmetry in Sunspot Emergence:
    The Role of the Wilson Depression
Authors: Watson, F.; Fletcher, L.; Dalla, S.; Marshall, S.
2009SoPh..260....5W    Altcode: 2009arXiv0909.0914W
  The distributions of sunspot longitude at first appearance and at
  disappearance display an east-west asymmetry that results from a
  reduction in visibility as one moves from disk centre to the limb. To
  first order, this is explicable in terms of simple geometrical
  foreshortening. However, the centre-to-limb visibility variation is
  much larger than that predicted by foreshortening. Sunspot visibility
  is also known to be affected by the Wilson effect: the apparent `dish'
  shape of the sunspot photosphere caused by the temperature-dependent
  variation of the geometrical position of the τ=1 layer. In this article
  we investigate the role of the Wilson effect on the sunspot appearance
  distributions, deducing a mean depth for the umbral τ=1 layer of 500
  - 1500 km. This is based on the comparison of observations of sunspot
  longitude distribution and Monte Carlo simulations of sunspot appearance
  using different models for spot growth rate, growth time and depth of
  Wilson depression.

---------------------------------------------------------
Title: Observations of a solar flare and filament eruption in Lyman
    α and X-rays
Authors: Rubio da Costa, F.; Fletcher, L.; Labrosse, N.; Zuccarello, F.
2009A&A...507.1005R    Altcode: 2009arXiv0909.4705R
  Context: Lα is a strong chromospheric emission line, which has been
  relatively rarely observed in flares. The Transition Region and Coronal
  Explorer (TRACE) has a broad “Lyman α” channel centered at 1216
  Å used primarily at the beginning of the mission. A small number of
  flares were observed in this channel. <BR />Aims: We aim to characterise
  the appearance and behaviour of a flare and filament ejection which
  occurred on 8th September 1999 and was observed by TRACE in Lα, as well
  as by the Yohkoh Soft and Hard X-ray telescopes. We explore the flare
  energetics and its spatial and temporal evolution. We have in mind the
  fact that the Lα line is a target for the Extreme Ultraviolet Imaging
  telescope (EUI) which has been selected for the Solar Orbiter mission,
  as well as the LYOT telescope on the proposed SMESE mission. <BR
  />Methods: We use imaging data from the TRACE 1216 Å, 1600 Å and
  171 Å channels, and the Yohkoh hard and soft X-ray telescopes. A
  correction is applied to the TRACE data to obtain a better estimate of
  the pure Lα signature. The Lα power is obtained from a knowledge of
  the TRACE response function, and the flare electron energy budget is
  estimated by interpreting Yohkoh/HXT emission in the context of the
  collisional thick target model. <BR />Results: We find that the Lα
  flare is characterised by strong, compact footpoints (smaller than the
  UV ribbons) which correlate well with HXR footpoints. The Lα power
  radiated by the flare footpoints can be estimated, and is found to be
  on the order of 10<SUP>26</SUP> erg s<SUP>-1</SUP> at the peak. This is
  less than 10% of the power inferred for the electrons which generate
  the co-spatial HXR emission, and can thus readily be provided by
  them. The early stages of the filament eruption that accompany the
  flare are also visible, and show a diffuse, roughly circular spreading
  sheet-like morphology, with embedded denser blobs. <BR />Conclusions:
  On the basis of this observation, we conclude that flare and filament
  observations in the Lα line with the planned EUI and LYOT telescopes
  will provide valuable insight into solar flare evolution and energetics,
  especially when accompanied by HXR imaging and spectroscopy.

---------------------------------------------------------
Title: Infrared and Microwave Observations of Uranus: Implications
    for Temperature, Composition, Circulation and a Standard Calibration
    Model for Herschel
Authors: Hofstadter, Mark D.; Orton, G.; Fletcher, L.; Mainzer, A.;
   Merlet, C.; Hines, D.; Hammel, H.; Burgdorf, M.; Moses, J.; Butler,
   B.; Gurwell, M.
2009DPS....41.2803H    Altcode:
  The Spitzer Infrared Spectrometer observed Uranus in December 2007
  between 5 and 21.5 microns. Disk-averaged temperatures are retrieved
  between 2 bars and the microbar level, yielding a profile warmer than
  found by Voyager 2. A substantial rise in temperature near 8 microbars
  is also found - consistent with Voyager results. The methane mixing
  ratio, constrained by 7-micron emission, is between 5% and 60% of
  saturation at the Tropopause. The presence of both absorption and
  emission by CH4 and CH3D will allow us to constrain the D/H ratio
  and the mixing ratio of methane in the 2-bar region. The abundance
  of stratospheric hydrocarbons varies strongly with longitude, while
  temperature does not. Minimal longitudinal and latitudinal variability
  of tropospheric temperatures indicates that Uranus may be adequate as
  a calibration source in the far-infrared through the submillimeter,
  which is useful to the Herschel Space Telescope. Strong latitudinal
  gradients in composition, however, as revealed by imaging at 1 mm to 20
  cm, do need to be accounted for. The Submillimeter Array imaged Uranus
  in 2006 at 1.4 mm, and the Very Large Array imaged Uranus between 2005
  and 2009 at wavelengths from 7 mm to 20 cm. These data indicate there
  is a latitudinally varying abundance of a microwave absorber near the
  1-bar level, with H2S being a likely candidate. The disk-averaged IR
  data confirms the presence of an opacity source besides that of H2 in
  this altitude region. The VLA data also imply an unexpected vertical
  distribution of opacity at pressures of tens-of-bars in the equatorial
  region, believed to be related to the liquid-water cloud. Much of
  this work was carried out at JPL/Caltech, under contract with NASA. We
  acknowledge the support of NASA's Planetary Astronomy and Atmospheres
  programs, and the Spitzer, SMA, VLA, and VLT observatories.

---------------------------------------------------------
Title: First Observations of the 2009 Collision in Jupiter's
    Atmosphere
Authors: Orton, Glenn S.; Fletcher, L.; Wesley, A.; Yanamandra-Fisher,
   P.; Fisher, B.; Mousis, O.; Golisch, W.; de Pater, I.; Marchis, F.;
   Kalas, P.; Fitzgerald, M.; Graham, J.; Wong, M.; Rogers, J.; Momary,
   T.; Sanchez-Lavega, A.; Hammel, H.; Simon-Miller, A.
2009DPS....41.1001O    Altcode:
  We report initial observations of the debris from the first
  documented impact of a body with Jupiter since the collisions of
  Comet Shoemaker-Levy 9 fragments 15 years ago. Visible observations
  by AW at 14:01 UT on 2009 July 19 recorded an unusual blackened
  region with fainter ejecta near the edge of Jupiter's South Polar
  Region. 0.89-micron CH<SUB>4</SUB> band imaging (A. Cidadao, D. Peach)
  on the subsequent rotation showed this site to be bright. Two rotations
  later at NASA's IRTF, a series of near-IR (1.58-4.78 micron) images with
  SpeX and NSFCam2 were recorded which verified the unmistakable signature
  of high-altitude particulate debris in even stronger CH<SUB>4</SUB>
  and H<SUB>2</SUB> absorption. Spectra were also recorded in the 0.8-2.5
  micron region. Images of thermal emission between 7 and 25 microns with
  MIRSI instrument recorded enhanced emission associated with ammonia gas
  and an increase of temperatures in the upper troposphere at the site of
  the impact and debris field. No enhancement of temperatures was detected
  near the 10-mbar level of the stratosphere. During the same rotation,
  Keck-II NIRC2 images at 2.124 microns detected an impact site, centered
  at 305±1.5°W longitude and 57±1.5°S planetographic latitude,
  with two prominent features and an ejecta field annulus which extends
  toward the west by 10° in longitude. The distinct detail of the initial
  images and references to existing images suggest that the impact may
  have occurred within a 10-hour period before its initial detection in
  the visible. Comparisons with published analyses of the Shoemaker-Levy
  9 impacts suggest an impactor on the order of hundreds of meters in
  size, something unlikely to have been detected in advance. There is no
  evidence at any wavelength for additional impacts. As of this writing,
  a vigorous campaign to characterize the impact site is being mounted
  at several observatories, and more details will inevitably follow.

---------------------------------------------------------
Title: The Case for Uranus and Neptune
Authors: Hofstadter, Mark D.; Sotin, C.; Brooks, S.; Fletcher,
   L.; Friedson, A.; Moeller, R.; Murphy, N.; Orton, G.; Spilker, T.;
   Wenkert, D.
2009DPS....41.1606H    Altcode:
  Uranus and Neptune are composed mostly of ices, such as H2O, making
  them fundamentally different from Jupiter or Saturn. These ice giants,
  and their unique satellites and rings, have an important story to
  tell us about the formation, evolution, and structure of planets in
  our Solar System and beyond. To understand that story, we must learn
  the basic properties of their interiors. We do not know if they have
  extensive solid- or liquid-water layers (making them almost overgrown
  icy satellites) or if the H2O-H2 phase diagram allows structures unlike
  any other planet in our solar system. How internal heat is transported
  through the interior and atmosphere is also important to learn. We
  wish to know the nature of atmospheric convection and circulation and
  how they relate to internal and solar forcing. We also wish to know the
  composition and temperature of the atmosphere as a function of latitude,
  altitude, and time. One of the great surprises of the Voyager encounters
  was the discovery of strongly tilted dipole magnetic fields, offset
  from the planet's centers. How and where is the field generated? How
  does its unique geometry affect the transfer of energy from the solar
  wind to the magnetosphere? A mission to Uranus or Neptune, supported
  by healthy ground-based observing and laboratory campaigns, should be a
  priority for the next decade. Either planet can serve as the archetypal
  ice giant, but cross-disciplinary priorities can be used to choose one
  over the other. A recent JPL study identified trajectories that could
  deliver significant science payloads into orbit around either planet,
  and found that it may be possible to do so at Uranus for under the New
  Frontiers cost cap and using solar-power. This research was carried
  out at JPL/Caltech under contract with NASA.

---------------------------------------------------------
Title: Saturn Atmospheric Science in the Next Decade
Authors: Orton, Glenn S.; Fletcher, L.; Stallard, T.; Baines, K.;
   Sayanagi, K.; Huestis, D.; Yung, Y.; Edgington, S.; Gulkis, S.; Moses,
   J.; Martin-Torres, F.
2009DPS....41.1603O    Altcode:
  Although observed from the Earth, Pioneer 11, Voyagers 1 and 2, and now
  Cassini in its primary and 2-year extended mission, the characterization
  of fundamental atmospheric properties and processes in Saturn remains
  incomplete. Many open questions about the atmosphere could be addressed
  in the next decade: <P />- SEASONS: How do seasons affect (a) the global
  distribution of gaseous constituents and aerosols; and (b) temperatures
  and the stability against convection and large scale-atmospheric
  transport? Will a warm polar vortex appear at the northern pole with
  greater radiative input? <P />- HEXAGON: What is the vertical structure
  of the hexagon, what is driving and maintaining it; and why is there
  no feature of similar longevity at the south pole? <P />- COMPOSITION
  AND CHEMISRY: What are the noble gas and oxygen abundances? What is
  the relation of stratospheric hydrocarbon distributions to radiative
  climate influences and photochemistry? What is the rate of influx of
  ring and other exogenic materials into the atmosphere? <P />- CLOUDS
  AND HAZES: What is the tropospheric cloud inventory, and what are the
  different cloud compositions and optical properties? What is producing
  the haze material? What is the relation between observable clouds
  and lightning discharges? What is the relation between the fine-scale
  cloud structure identified at 5 microns and the <P />distribution of
  condensates, such as ammonia? Do 5-micron clouds have counterparts
  at other altitude levels? <P />- DYNAMICS: What is the source of the
  strong equatorial upwelling and strong prograde jet? What changes when
  we see the emergence of Great White Storms? How is energy transported
  by waves between atmospheric levels, via the SAO and by vertical waves
  observed in stellar occultations and RSS profiles? What effect does
  the ephemeral nature of Saturn's slowly-moving thermal waves have on
  the atmosphere? Will the tropospheric hotspots at each pole persist?

---------------------------------------------------------
Title: Meridional Distributions of Methylacetylene and Diacetylene
    in Saturn's Stratosphere from CIRS/Cassini Observations.
Authors: Guerlet, Sandrine; Fouchet, T.; Moses, J. I.; Fletcher,
   L. N.; Bézard, B.; Simon-Miller, A. A.; Flasar, F. M.
2009DPS....41.2804G    Altcode:
  The Composite InfraRed Spectrometer (CIRS) aboard the Cassini spacecraft
  provides a unique opportunity to perform limb observations of Saturn's
  stratosphere. This viewing geometry favors the detection of minor
  species and allows the retrieval of their abundance profile with
  a larger vertical extent and higher vertical resolution than nadir
  observations. <P />Following our work on acetylene, ethane and propane
  (Guerlet et al. 2009), we will present the first maps of the volume
  mixing ratio of methylacetylene (CH3C2H) and diacetylene (C4H2), from
  45°N to 80°S and 3 mbar to 0.05 mbar. These results were obtained from
  an analysis of CIRS limb observations using a line-by-line radiative
  transfer model coupled to an inversion algorithm. We have also analyzed
  sets of nadir CIRS spectra, which are sensitive to C4H2 around 0.5
  mbar, extending the meridional coverage up to 88°S and 65°N at this
  pressure level. <P />These molecules are minor by-products of the
  methane photochemistry, but their abundances give important insights
  on the main chemical pathways, as we will show their distributions
  compare with our previously derived C2H2 variations. C4H2 and CH3C2H
  have also rather short lifetimes (25-80 years at 1 mbar) compared to
  the main hydrocarbons' lifetimes (ethane and acetylene, resp. 700 and
  100 years at 1 mbar) making them good tracers of seasonal stratospheric
  dynamics. They display some small-scale variations in their meridional
  distribution which could be symptomatic of vertical and/or meridional
  dynamics. We will compare the distribution of C3H4 and C4H2 we derived
  with the predictions of the photochemical seasonal model of Julie Moses
  (Moses and Greathouse, 2005).

---------------------------------------------------------
Title: Changing Seasons on Saturn: If Winter's Here, Can Spring be
    Far Behind?
Authors: Yanamandra-Fisher, Padma A.; Orton, G. S.; Fisher, B. M.;
   Baines, K.; Fletcher, L.; Fujiyoshi, T.; Fuse, T.
2009DPS....41.2805Y    Altcode:
  Ground-based near- and mid-infrared observations of Saturn from 1995
  - 2009, covering half a Saturnian year, provide a rich data set to
  model seasonal changes in both Saturn's atmosphere and its rings as
  a function of solar elevation. We acquired near-infrared data from
  NASA/Infrared Telescope Facility (IRTF); and mid-infrared data from
  NASA/IRTF and NAOJ/Subaru Facility. Our data set covers the period
  from autumnal equinox (1995) to the upcoming vernal equinox (2009); and
  provides a bridge between Voyager encounters and Cassini prime mission,
  with temporal and spatial context for spacecraft observations. We
  shall present results illustrating: (1) changes in thermal fields on
  the planet; (2) evolution/distribution of various chemical species;
  (3) development of clouds and other discrete features; (4) thermal
  properties of the main rings and (5) models for these trends.

---------------------------------------------------------
Title: Unsteady signatures from solar flares: reconnection,
    acceleration or transport?
Authors: Fletcher, Lyndsay; Liu, Siming
2009shin.confE.195F    Altcode:
  The energy for solar flares is liberated from coronal stored energy
  via the process of reconnection. Observationally, solar flares are
  inherently bursty, in time and in space. The primary signatures
  of flare energy release are produced by accelerated electrons and
  ions, i.e. hard X-rays and gamma-rays, and radio. White light and
  ultraviolet chromospheric emission are also closely related to
  the primary energy release. All of these signatures demonstrate
  intermittency, on timescales from tens of milliseconds up to some
  tens of seconds. However, it is not clear from the outset how much
  of this intermittency is due to the energy release process, how much
  to the acceleration process, and how much to the energy transport
  process. I will review the flare main observations and discuss what
  each observable timescale might tell us about the basic processes
  associated with flare energisation.

---------------------------------------------------------
Title: Elementary Energy Release Events in Solar Flares
Authors: Liu, Siming; Fletcher, Lyndsay
2009ApJ...701L..34L    Altcode: 2009arXiv0907.1874L
  Most theoretical investigations of particle acceleration during solar
  flares cannot be applied to observations for detailed study of the time
  evolution. We propose a phenomenological model for turbulence evolution
  and stochastic particle acceleration that links observations to the
  energy release and particle acceleration through two coefficients
  characterizing particle interactions with turbulent electromagnetic
  fields. In the linear regime the particle distribution does not affect
  the turbulence energy cascade. It is shown that electron acceleration
  critically depends on the intensity of small-scale turbulence and
  an impulsive nonthermal component only appears near the peak of the
  gradually evolving turbulence intensity. The model naturally reproduces
  the soft-hard-soft pattern of hard X-ray pulses, and we attribute
  the observed change in flux and spectral index correlation from
  the rise to decay phase of some pulses to changes in the background
  plasma. Detailed modeling of well observed individual events will
  probe the energy release processes.

---------------------------------------------------------
Title: Phosphine on Jupiter and Saturn from Cassini/CIRS
Authors: Fletcher, L. N.; Orton, G. S.; Teanby, N. A.; Irwin, P. G. J.
2009Icar..202..543F    Altcode:
  The global distribution of phosphine (PH <SUB>3</SUB>) on Jupiter
  and Saturn is derived using 2.5 cm <SUP>-1</SUP> spectral resolution
  Cassini/CIRS observations. We extend the preliminary PH <SUB>3</SUB>
  analyses on the gas giants [Irwin, P.G.J., and 6 colleagues,
  2004. Icarus 172, 37-49; Fletcher, L.N., and 9 colleagues, 2007a. Icarus
  188, 72-88] by (a) incorporating a wider range of Cassini/CIRS datasets
  and by considering a broader spectral range; (b) direct incorporation
  of thermal infrared opacities due to tropospheric aerosols and (c)
  using a common retrieval algorithm and spectroscopic line database
  to allow direct comparison between these two gas giants. The results
  suggest striking similarities between the tropospheric dynamics in
  the 100-1000 mbar regions of the giant planets: both demonstrate
  enhanced PH <SUB>3</SUB> at the equator, depletion over neighbouring
  equatorial belts and mid-latitude belt/zone structures. Saturn's
  polar PH <SUB>3</SUB> shows depletion within the hot cyclonic polar
  vortices. Jovian aerosol distributions are consistent with previous
  independent studies, and on Saturn we demonstrate that CIRS spectra
  are most consistent with a haze in the 100-400 mbar range with a mean
  optical depth of 0.1 at 10 μm. Unlike Jupiter, Saturn's tropospheric
  haze shows a hemispherical asymmetry, being more opaque in the
  southern summer hemisphere than in the north. Thermal-IR haze opacity
  is not enhanced at Saturn's equator as it is on Jupiter. Small-scale
  perturbations to the mean PH <SUB>3</SUB> abundance are discussed both
  in terms of a model of meridional overturning and parameterisation
  as eddy mixing. The large-scale structure of the PH <SUB>3</SUB>
  distributions is likely to be related to changes in the photochemical
  lifetimes and the shielding due to aerosol opacities. On Saturn, the
  enhanced summer opacity results in shielding and extended photochemical
  lifetimes for PH <SUB>3</SUB>, permitting elevated PH <SUB>3</SUB>
  levels over Saturn's summer hemisphere.

---------------------------------------------------------
Title: Signatures of spatially extended reconnection in solar flares
Authors: Fletcher, Lyndsay
2009shin.confE.162F    Altcode:
  Solar flare ribbons, visible in H alpha and ultraviolet, suggest
  strongly that flare reconnection happens not just in one or two spots in
  the corona but over an extended region. X-ray and white light footpoints
  on the other hand usually only occur in a couple of locations. What can
  we say about the spatial extent and distribution of coronal reconnection
  sites from such observations? In this talk I will discuss some recent
  observations and simulations of 3D reconnection, and whether they
  together provide evidence for large-scale (i.e. active-region scale)
  current sheets.

---------------------------------------------------------
Title: Jupiter
Authors: Marchis, F.; Hueso Alonso, R.; Mousis, O.; Orton, G.;
   Fletcher, L.; Perez-Hoyos, S.; Keck, W. M., II
2009IAUC.9060....3M    Altcode: 2009IAUC.9060C...1M
  F. Marchis, University of California at Berkeley and SETI Institute; and
  R. Hueso Alonso, University of the Basque Country, further report on a
  preliminary analysis of observations of Jupiter's atmosphere collected
  by O. Mousis, Observatoire de Besancon; G. Orton and L. Fletcher,
  Jet Propulsion Laboratory; and S. Perez-Hoyos, University of the
  Basque Country, recorded with the Very Large Telescope (Yepun) and its
  adaptive-optics system NACO during July 26.311-26.370. Images taken
  with the IB248 filter (centered at 2.48 microns; width 0.06 microns)
  revealed that the feature located between 295 deg and 315 deg west
  longitude (in System III) and centered at 55 deg south latitude has
  a significantly evolved shape by comparison with the Keck telescope
  K_p (2.12 microns) data taken on July 20.468 (noted above). Six days
  after this observation, the two maxima are now barely distinguishable,
  separated by 8 deg in latitude. The brightest peak is centered at
  312 deg west. The continued longitudinal shearing is consistent with
  several amateur observations of the site and with the behavior of the
  impact sites associated with the impacts of D/1993 F2 in 1994.

---------------------------------------------------------
Title: Observations of conduction driven evaporation in the early
    rise phase of solar flares
Authors: Battaglia, M.; Fletcher, L.; Benz, A. O.
2009A&A...498..891B    Altcode: 2009arXiv0903.2754B
  Context: The classical flare picture features a beam of electrons, which
  were accelerated in a site in the corona, hitting the chromosphere. The
  electrons are stopped in the dense chromospheric plasma, emitting
  bremsstrahlung in hard X-rays. The ambient material is heated by the
  deposited energy and expands into the magnetic flare loops, a process
  termed chromospheric evaporation. In this view hard X-ray emission from
  the chromosphere is succeeded by soft-X-ray emission from the hot plasma
  in the flare loop, the soft X-ray emission being a direct consequence
  of the impact of the non-thermal particle beam. However, observations
  of events exist in which a pronounced increase in soft X-ray emission
  is observed minutes before the onset of the hard X-ray emission. Such
  pre-flare emission clearly contradicts the classical flare picture. <BR
  />Aims: For the first time, the pre-flare phase of such solar flares
  is studied in detail. The aim is to understand the early rise phase of
  these events. We want to explain the time evolution of the observed
  emission by means of alternative energy transport mechanisms such as
  heat conduction. <BR />Methods: RHESSI events displaying pronounced
  pre-flare emission were analyzed in imaging and spectroscopy. The time
  evolution of images and full sun spectra was investigated and compared
  to the theoretical expectations from conduction driven chromospheric
  evaporation. <BR />Results: The pre-flare phase is characterized by
  purely thermal emission from a coronal source with increasing emission
  measure and density. After this earliest phase, a small non-thermal
  tail to higher energies appears in the spectra, becoming more and
  more pronounced. However, images still only display one X-ray source,
  implying that this non-thermal emission is coronal. The increase of
  emission measure and density indicates that material is added to the
  coronal region. The most plausible origin is evaporated material from
  the chromosphere. Energy provided by a heat flux is capable of driving
  chromospheric evaporation. We show that the often used classical Spitzer
  treatment of the conductive flux is not applicable. The conductive
  flux is saturated. During the preflare-phase, the temperature of the
  coronal source remains constant or increases. Continuous heating in the
  corona is necessary to explain this observation. <BR />Conclusions:
  The observations of the pre-flare phase of four solar flares are
  consistent with chromospheric evaporation driven by a saturated heat
  flux. Additionally, continuous heating in the corona is necessary to
  sustain the observed temperature.

---------------------------------------------------------
Title: Hard X-ray Emission From A Flare-related Jet
Authors: Bain, Hazel; Fletcher, L.
2009SPD....40.3606B    Altcode:
  Solar X-ray jets were first observed by Yohkoh (Shibata 1992,
  Strong 1992). During these events, collimated flows of plasma
  are accelerated in the corona. Previous observations have detected
  jet-related electrons directly in space as well as via radio signatures
  (type III bursts). However the major diagnostic of fast electrons
  is bremsstrahlung X-ray emission, but until now we have never seen
  any evidence of hard X-ray emission directly from the jet in the
  corona. This could be because it is rare to find a coronal jet dense
  enough to provide a bremsstrahlung target for the electrons, or hot
  enough to generate high energy thermal emission. We report what we
  believe to be the first observation of hard X-ray emission formed in
  a coronal jet. The event occurred on the 22nd of August 2002 and its
  evolution was observed by a number of instruments. In particular we
  study the pre-impulsive and impulsive phase of the flare using data
  from RHESSI, TRACE and the Nobeyama Radioheliograph. During this period
  RHESSI observed significant hard X-ray emission to energies as high as
  50 keV in the jet. Radio observations from the Nobeyama Radioheliograph
  show a positive spectral index for the ejected material, which may be
  explained by optically-thick gyrosynchrotron emission from non-thermal
  electrons in the jet. <P />HMB gratefully acknowledges the support of
  an SPD and STFC studentship. LF gratefully acknowledges the support of
  an STFC Rolling Grant, and financial support by the European Commission
  through the SOLAIRE Network (MTRN-CT_2006-035484)

---------------------------------------------------------
Title: Flares and the chromosphere
Authors: Hudson, Hugh S.; Fletcher, Lyndsay
2009EP&S...61..577H    Altcode: 2009EP&S...61L.577H
  The chromosphere (the link between the photosphere and the corona)
  plays a crucial role in flare and CME development. In analogies between
  flares and magnetic substorms, it is normally identified with the
  ionosphere, but we argue that the correspondence is not exact. Much
  of the important physics of this interesting region remains to be
  explored. We discuss chromospheric flares in the context of recent
  observations of white-light flares and hard X-rays as observed by
  TRACE and RHESSI, respectively. We interpret key features of these
  observations as results of the stepwise changes a flare produces in
  the photospheric magnetic field.

---------------------------------------------------------
Title: A “perfect” Late Phase Flare Loop: X-ray And Radio Studies
Authors: Bain, Hazel; Fletcher, L.
2009SPD....40.1917B    Altcode:
  We present observations of a GOES X3.1 class flare which occurred on the
  24th August 2002. The event was observed by a number of instruments
  including RHESSI, TRACE and NoRH. This flare is particularly
  interesting due to its position and orientation on the west limb
  of the Sun. The flare appears to be perpendicular to the line of
  sight making it possible to ascertain the geometrical parameters of
  the post flare arcade loops. We investigate the decay phase of the
  flare by comparing X-ray and radio observations of the post flare
  arcade loops with models of soft x-ray and thermal gyrosynchrotron
  emission to characterise the electron distribution present within the
  loop. <P />HMB gratefully acknowledges the support of an SPD and STFC
  studentship. LF gratefully acknowledges the support of an STFC Rolling
  Grant, and financial support by the European Commission through the
  SOLAIRE Network (MTRN-CT_2006-035484)

---------------------------------------------------------
Title: Change of Seasons on Jovian Planets: Ground-based High Spatial
    Thermal Observations
Authors: Yanamandra-Fisher, Padma A.; Orton, G.; Fletcher, L. N.;
   Fisher, B. M.; Fujiyoshi, T.; Fuse, T.; Hayward, T.; de Buizer, J.
2009AAS...21430504Y    Altcode:
  We report on the seasonal changes observed on all four of the solar
  system jovian planets, based on mid-infrared data acquired from
  several observatories (NASA/IRTF, NAOJ/Subaru, ESO/VLT) from 2005 to
  present. Jupiter's atmosphere underwent a global upheaval, from color
  transformation of discrete and axisymmetric features to interaction
  of giant vortices; Saturn is approaching its vernal equinox in August
  2009 and its cold northern hemisphere is emerging into sunlight after
  years of obscuration; Saturn rings are closing towards their edge-on
  apparition; Uranus underwent its equinox in 2007, where seasons last
  20 years and its north pole is warming up; and Neptune demonstrated
  a warm south pole, with a possible mechanism for escape of methane
  into the stratosphere. Although each planet is at a different stage
  of its seasonal cycle, taken together, our observations illustrate
  several overarching science investigations of the local meteorology
  on Jovian planets: What are the circulation patterns? What explains
  the warm south poles? What are the variations in the distribution of
  key chemical species such as ammonia, phosphine, and other hydrocarbons?

---------------------------------------------------------
Title: Evolution of an eruptive flare loop system
Authors: Romano, P.; Zuccarello, F.; Fletcher, L.; Rubio da Costa,
   F.; Bain, H. M.; Contarino, L.
2009A&A...498..901R    Altcode:
  Context: Flares, eruptive prominences and coronal mass ejections are
  phenomena where magnetic reconnection plays an important role. However,
  the location and the rate of the reconnection, as well as the mechanisms
  of particle interaction with ambient and chromospheric plasma are still
  unclear. <BR />Aims: In order to contribute to the comprehension of the
  above mentioned processes we studied the evolution of the eruptive flare
  loop system in an active region where a flare, a prominence eruption
  and a CME occurred on August 24, 2002. <BR />Methods: We measured the
  rate of expansion of the flare loop arcade using TRACE 195 Å images
  and determined the rising velocity and the evolution of the low and high
  energy hard X-ray sources using RHESSI data. We also fitted HXR spectra
  and considered the radio emission at 17 and 34 GHZ. <BR />Results:
  We observed that the top of the eruptive flare loop system initially
  rises with a linear behavior and then, after 120 mn from the start of
  the event registered by GOES at 1-8 Å, it slows down. We also observed
  that the heating source (low energy X-ray) rises faster than the top
  of the loops at 195 Å and that the high energy X-ray emission (30-40
  keV) changes in time, changing from footpoint emission at the very
  onset of the flare to being coincident during the flare peak with the
  whole flare loop arcade. <BR />Conclusions: The evolution of the loop
  system and of the X-ray sources allowed us to interpret this event in
  the framework of the Lin &amp; Forbes model (2000), where the absolute
  rate of reconnection decreases when the current sheet is located at an
  altitude where the Alfvén speed decreases with height. We estimated
  that the lower limit for the altitude of the current sheet is 6 ×
  10<SUP>4</SUP> km. Moreover, we interpreted the unusual variation of
  the high energy HXR emission as a manifestation of the non thermal
  coronal thick-target process which appears during the flare in a manner
  consistent with the inferred increase in coronal column density.

---------------------------------------------------------
Title: Saturn's north polar region at depth: The North Polar Hexagon
    and North Polar Cyclone observed over two years by Cassini/VIMS
Authors: Baines, K. H.; Momary, T. W.; Fletcher, L. N.; Kim, J. H.;
   Showman, A. P.; Atreya, S. K.; Brown, R. H.; Buratti, B. J.; Clark,
   R. N.; Nicholson, P. D.
2009EGUGA..11.3375B    Altcode:
  For over two years beginning in October, 2006, Saturn's north polar
  region has been observed periodically from clear vantage points over
  high northern latitudes by the Visual Infrared Mapping Spectrometer
  onboard the Cassini/Huygens orbiter, The latest observations,
  acquired on June 15 and December 16, 2008, are especially clear,
  as they were obtained from sub-spacecraft latitudes poleward of 70
  degrees N and at close range (&lt; 450,000 altitude for June; &lt;
  510,000 for December). With much of the polar region under nighttime
  conditions, we used Saturn's thermal glow as a source of light to
  map clouds in silhouette, monitoring their movement with time to
  determine the polar wind structure. We find a cyclone at the north
  pole, with winds exceeding 135 m/s near 88.3 degrees N. latitude
  (planetocentric, pc). The center of the cyclone, at the exact pole,
  is covered by a small (&lt; 500 km in diameter) cloud. Equatorward,
  winds fall off to ~10 m/s near the poleward edge of the hexagon near 78
  degrees pc. Within the hexagon itself, clouds move at ~ 125 m/s. The
  hexagon itself stays nearly fixed in the rotational system of Saturn
  established by Voyager. However, while the hexagonal feature stayed
  fixed to high accuracy from late 2006 through early 2008 (&lt;0.5
  deg of movement over 16 months), we find that since February, 2008,
  the hexagon has rotated 8.9 degrees in longitude in the retrograde
  direction. Between the detailed June and December 2008 observations,
  the feature rotated 1.2 degrees, retrograde, corresponding to
  0.0065 degree/day or 2 cm/s, retrograde. Beginning in June, 2008,
  sunlight is seen reaching cloud features within the hexagon as polar
  winter wanes. New results of cloudtop altitude are presented based
  on the reflected sunlight observed in various methane and hydrogen
  atmospheric absorption bands. These are compared to the cloud bottom
  pressures which we have determined to be near the 2-bar level based on
  analysis of 5-micron thermal spectra. Clouds observed in sunlight and
  at 5-micron are coherent, indicating little vertical shear in zonal
  winds in the north polar region.

---------------------------------------------------------
Title: Problems and Solutions in the Analysis of Spitzer IRS
Observations of Uranus and Neptune: Results for Temperature Structure
    and Composition
Authors: Orton, G.; Fletcher, L.; Mainzer, A.; Line, M.; Merlet, C.;
   Hines, D.; Hammel, H.; Burgdorf, M.; Moses, J.
2009EGUGA..11.3525O    Altcode:
  Mid-infrared spectra of the disks of Uranus and Neptune were obtained
  with Spitzer's very sensitive Infrared Spectrometer (IRS). The
  IRS covered the wavelength range of 5 to 21.5 μm with a resolving
  power of ~90 and of 10 to 36.5 μm with a resolving power of ~600,
  although there were problems with the high-resolution modes at
  the longest wavelengths. The spectra do not resolve the disks of
  either planet, but they are nonetheless replete with information
  about the global-mean temperature structure and composition of both
  planets. This presentation will concentrate on the approaches used
  to derive temperatures and compositions. Derivation of an average
  temperature profile will be demonstrated principally using spectra
  of Uranus, using the collision-induced absorption "continuum" and
  quadrupole lines of molecular hydrogen. Derivation of composition
  will be demonstrated princially using spectra of Neptune, covering
  features arising from methyl, methane, acetylene, ethyene, ethane,
  diacetylene, methylacetylene, and carbon dioxide. The benefits of
  recent improvements in spectroscopic parameters will be demonstrated,
  and the need for improvements in others outlined.

---------------------------------------------------------
Title: Partially-erupting prominences: a comparison between
    observations and model-predicted observables
Authors: Tripathi, D.; Gibson, S. E.; Qiu, J.; Fletcher, L.; Liu,
   R.; Gilbert, H.; Mason, H. E.
2009A&A...498..295T    Altcode: 2009arXiv0902.1228T
  Aims: We investigate several partially-erupting prominences to
  study their relationship with other CME-associated phenomena and
  compare these observations with observables predicted by a model
  of partially-expelled-flux-ropes (Gibson &amp; Fan 2006a, ApJ,
  637, L65; 2006b, J. Geophys. Res., 111, 12103). <BR />Methods: We
  studied 6 selected events with partially-erupting prominences using
  multi-wavelength observations recorded by the Extreme-ultraviolet
  Imaging Telescope (EIT), Transition Region and Coronal Explorer
  (TRACE), Mauna Loa Solar Observatory (MLSO), Big Bear Solar Observatory
  (BBSO), and Soft X-ray Telescope (SXT). The observational features
  associated with partially-erupting prominences were then compared
  with the predicted observables from the model. <BR />Results: The
  partially-expelled-flux-rope (PEFR) model can explain the partial
  eruption of these prominences, and in addition predicts a variety
  of other CME-related observables that provide evidence of internal
  reconnection during eruption. We find that all of the partially-erupting
  prominences studied in this paper exhibit indirect evidence of internal
  reconnection. Moreover, all cases showed evidence of at least one
  observable unique to the PEFR model, e.g., dimmings external to the
  source region and/or a soft X-ray cusp overlying a reformed sigmoid. <BR
  />Conclusions: The PEFR model provides a plausible mechanism to explain
  the observed evolution of partially-erupting-prominence-associated
  CMEs in our study.

---------------------------------------------------------
Title: Energy Release and Transfer in Solar Flares: Simulations of
    Three-Dimensional Reconnection
Authors: Birn, J.; Fletcher, L.; Hesse, M.; Neukirch, T.
2009ApJ...695.1151B    Altcode:
  Using three-dimensional magnetohydrodynamic simulations we investigate
  energy release and transfer in a three-dimensional extension of the
  standard two-ribbon flare picture. In this scenario, reconnection is
  initiated in a thin current sheet (suggested to form below a departing
  coronal mass ejection) above a bipolar magnetic field. Two cases are
  contrasted: an initially force-free current sheet (low beta) and a
  finite-pressure current sheet (high beta), where beta represents the
  ratio between gas (plasma) and magnetic pressure. The energy conversion
  process from reconnection consists of incoming Poynting flux turned
  into up- and downgoing Poynting flux, enthalpy flux, and bulk kinetic
  energy flux. In the low-beta case, the outgoing Poynting flux is the
  dominant contribution, whereas the outgoing enthalpy flux dominates
  in the high-beta case. The bulk kinetic energy flux is only a minor
  contribution in the downward direction. The dominance of the downgoing
  Poynting flux in the low-beta case is consistent with an alternative to
  the thick target electron beam model for solar flare energy transport,
  suggested recently by Fletcher &amp; Hudson, whereas the enthalpy
  flux may act as an alternative transport mechanism. For plausible
  characteristic parameters of the reconnecting field configuration, we
  obtain energy release timescales and energy output rates that compare
  favorably with those inferred from observations for the impulsive phase
  of flares. Significant enthalpy flux and heating are found even in the
  initially force-free case with very small background beta, resulting
  mostly from adiabatic compression rather than Ohmic dissipation. The
  energy conversion mechanism is most easily understood as a two-step
  process (although the two steps may occur essentially simultaneously):
  the first step is the acceleration of the plasma by Lorentz forces
  in layers akin to the slow shocks in the Petschek reconnection
  model, involving the conversion of magnetic energy to bulk kinetic
  energy. However, due to pressure gradient forces that oppose the Lorentz
  forces in approximate, or partial force balance, the accelerated plasma
  becomes slowed down and compressed, whereby the bulk kinetic energy
  is converted to heat, either locally deposited or transported away by
  enthalpy flux and deposited later. This mechanism is most relevant in
  the downflow region, which is more strongly governed by force balance;
  it is less important in the outflow above the reconnection site,
  where more energy remains in the form of fast bulk flow.

---------------------------------------------------------
Title: Inertial Alfvén Wave Acceleration of Solar Flare Electrons
Authors: McClements, K. G.; Fletcher, L.
2009ApJ...693.1494M    Altcode:
  The possibility that electrons could be accelerated by inertial Alfvén
  waves to hard X-ray-emitting energies in the low solar corona during
  flares is investigated theoretically. This investigation is prompted
  in part by recent microwave observations indicating that the coronal
  magnetic field is strong enough that the Alfvén velocity c<SUB>A</SUB>
  above active regions could be of the order of a tenth of the speed of
  light or more; electrons can be accelerated to velocities in excess of
  c<SUB>A</SUB> on collisionless timescales via reflection by a single
  inertial Alfvén wave pulse. It is shown that the fraction of particles
  accelerated is a sensitive function of the initial electron temperature
  and the transverse length scale δx of the shear Alfvén wave pulse;
  under typical pre-flare coronal conditions, a significant fraction of
  the electron population can be accelerated if δx is of the order of
  a few meters or less.

---------------------------------------------------------
Title: Retrievals of atmospheric variables on the gas giants from
    ground-based mid-infrared imaging
Authors: Fletcher, L. N.; Orton, G. S.; Yanamandra-Fisher, P.; Fisher,
   B. M.; Parrish, P. D.; Irwin, P. G. J.
2009Icar..200..154F    Altcode:
  Thermal-infrared imaging of Jupiter and Saturn using the NASA/IRTF
  and Subaru observatories are quantitatively analyzed to assess
  the capabilities for reproducing and extending the zonal mean
  atmospheric results of the Cassini/CIRS experiment. We describe the
  development of a robust, systematic and reproducible approach to the
  acquisition and reduction of planetary images in the mid-infrared
  (7-25 μm), and perform an adaptation and validation of the optimal
  estimation, correlated- k retrieval algorithm described by Irwin
  et al. [Irwin, P., Teanby, N., de Kok, R., Fletcher, L., Howett,
  C., Tsang, C., Wilson, C., Calcutt, S., Nixon, C., Parrish, P.,
  2008. J. Quant. Spectrosc. Radiat. Trans. 109 (6), 1136-1150] for
  channel-integrated radiances. Synthetic spectral analyses and a
  comparison to Cassini results are used to verify our abilities to
  retrieve temperatures, haze opacities and gaseous abundances from
  filtered imaging. We find that ground-based imaging with a sufficiently
  high spatial resolution is able to reproduce the three-dimensional
  temperature and para-H <SUB>2</SUB> fields measured by spacecraft
  visiting Jupiter and Saturn, allowing us to investigate vertical wind
  shear, pressure and, with measured cloud-top winds, Ertel potential
  vorticity on potential temperature surfaces. Furthermore, by scaling
  vertical profiles of NH <SUB>3</SUB>, PH <SUB>3</SUB>, haze opacity
  and hydrocarbons as free parameters during thermal retrievals, we
  can produce meridional results comparable with CIRS spectroscopic
  investigations. This paper demonstrates that mid-IR imaging instruments
  operating at ground-based observatories have access to several
  dynamical and chemical diagnostics of the atmospheric state of the
  gas giants, offering the prospect for quantitative studies over much
  longer baselines and often covering much wider areas than is possible
  from spaceborne platforms.

---------------------------------------------------------
Title: Methane and its isotopologues on Saturn from Cassini/CIRS
    observations
Authors: Fletcher, L. N.; Orton, G. S.; Teanby, N. A.; Irwin, P. G. J.;
   Bjoraker, G. L.
2009Icar..199..351F    Altcode:
  High spectral resolution observations from the Cassini Composite
  Infrared Spectrometer [Flasar, F.M., and 44 colleagues, 2004. Space
  Sci. Rev. 115, 169-297] are analysed to derive new estimates
  for the mole fractions of CH <SUB>4</SUB>, CH <SUB>3</SUB>D and
  <SUP>13</SUP>CH <SUB>4</SUB> of (4.7±0.2)×10, (3.0±0.2)×10 and
  (5.1±0.2)×10 respectively. The mole fractions show no hemispherical
  asymmetries or latitudinal variability. The analysis combines data
  from the far-IR methane rotational lines and the mid-IR features
  of methane and its isotopologues, using both the correlated- k
  retrieval algorithm of Irwin et al. [Irwin, P., and 9 colleagues,
  2008. J. Quant. Spectrosc. Radiat. Trans. 109, 1136-1150] and a
  line-by-line approach to evaluate the reliability of the retrieved
  quantities. C/H was found to be enhanced by 10.9±0.5 times the
  solar composition of Grevesse et al. [Grevesse, N., Asplund, M.,
  Sauval, A., 2007. Space Sci. Rev. 130 (1), 105-114], 2.25±0.55
  times larger than the enrichment on Jupiter, and supporting the
  increasing fractional core mass with distance from the Sun predicted
  by the core accretion model of planetary formation. A comparison of
  the jovian and saturnian C/N, C/S and C/P ratios suggests different
  reservoirs of the trapped volatiles in a primordial solar nebula whose
  composition varies with distance from the Sun. This is supported by
  our derived D/H ratio in methane of (1.6±0.2)×10, which appears to
  be smaller than the jovian value of Lellouch et al. [Lellouch, E.,
  Bézard, B., Fouchet, T., Feuchtgruber, H., Encrenaz, T., de Graauw,
  T., 2001. Astron. Astrophys. 370, 610-622]. Mid-IR emission features
  provided an estimate of C12/C13=91.8-7.8+8.4, which is consistent with
  both the terrestrial ratio and jovian ratio, suggesting that carbon
  was accreted from a shared reservoir for all of the planets.

---------------------------------------------------------
Title: Ultra-violet footpoints as tracers of coronal magnetic
    connectivity and restructuring during a solar flare
Authors: Fletcher, L.
2009A&A...493..241F    Altcode:
  Context: The bright, compact ultraviolet sources that appear in flare
  ribbons are interpreted as sites of energisation of the chromosphere,
  most likely by electron beams from the corona. Previously we have
  developed an algorithm to track these compact sources in observations by
  the Transition Region and Coronal Explorer (TRACE), recording position
  and intensity. We now exploit this further. <BR />Aims: We aim at
  identifying conjugate footpoint pairs by cross-correlating the TRACE
  1600 Å lightcurves in one particular event - the 2002-July-17 M 8.5
  flare. We also seek the spatial relationship between the magnetic flux
  transfer (reconnection) rate, well-connected locations, and energy input
  by electrons. <BR />Methods: We performed wavelet à trous filtering
  on the UV light curves, followed by a linear cross-correlation,
  to identify well-correlated pairs. We used RHESSI data to determine
  the locations of strong electron beam input. <BR />Results: Maps of
  footpoint pairs were produced in which we can identify well-separated
  locations that have well-correlated 1600 Å light curves. The time
  lag between credible conjugate footpoint brightenings can be a few
  seconds. The flare magnetic connectivity is found to evolve with
  time. RHESSI hard X-ray sources are found where the flux transfer
  rate is highest. <BR />Conclusions: We propose that the correlated
  footpoints are in fact conjugate pairs that are magnetically linked. In
  some instances, this linkage may be via a coronal null. The time lag
  in many cases is consistent with excitation by relativistic particles,
  but correlations with a longer time lag may suggest excitation by waves.

---------------------------------------------------------
Title: Commission 10: Solar Activity
Authors: Klimchuk, James A.; van Driel-Gesztelyi, Lidia; Schrijver,
   Carolus J.; Melrose, Donald B.; Fletcher, Lyndsay; Gopalswamy,
   Natchimuthuk; Harrison, Richard A.; Mandrini, Cristina H.; Peter,
   Hardi; Tsuneta, Saku; Vršnak, Bojan; Wang, Jing-Xiu
2009IAUTA..27...79K    Altcode: 2008arXiv0809.1444K
  Commission 10 deals with solar activity in all of its forms,
  ranging from the smallest nanoflares to the largest coronal mass
  ejections. This report reviews scientific progress over the roughly
  two-year period ending in the middle of 2008. This has been an exciting
  time in solar physics, highlighted by the launches of the Hinode and
  STEREO missions late in 2006. The report is reasonably comprehensive,
  though it is far from exhaustive. Limited space prevents the inclusion
  of many significant results. The report is divided into the following
  sections: Photosphere and chromosphere; Transition region; Corona and
  coronal heating; Coronal jets; flares; Coronal mass ejection initiation;
  Global coronal waves and shocks; Coronal dimming; The link between low
  coronal CME signatures and magnetic clouds; Coronal mass ejections in
  the heliosphere; and Coronal mass ejections and space weather. Primary
  authorship is indicated at the beginning of each section.

---------------------------------------------------------
Title: Polar Phenomena in Outer Planet Atmospheres
Authors: Orton, G.; Fletcher, L.; Yanamandra-Fisher, P.; Leyrat, C.;
   Greathouse, T.; Parrish, P.; Encrenaz, T.; Simon-Miller, A.
2008AGUFM.P11B1272O    Altcode:
  Infrared observations of the polar regions of the outer planets
  have revealed similarities to the Earth's atmosphere and some new
  phenomena. The most dominant force which is apparent in time-dependent
  studies of the poles is seasonal radiative forcing, which was detected
  in Saturn's stratosphere as early as 1973. For Saturn, Uranus and
  Neptune, planets with substantial obliquities, the seasonally dependent
  changes are predictable and can be used to constrain abundances of
  optically active gases and the rate of restoration by stratospheric
  circulation. In the case of Neptune, recent evidence shows that the
  heating is sufficient to allow a "leak" from the reservoir of methane
  in the deep atmosphere into the polar stratosphere. New thermal images
  of Uranus show that the winter pole of Uranus which has only recently
  emerged fully from darkness is colder than when it was in the middle of
  winter when Voyager 2 visited, confirming the substantial seasonal phase
  delay associated with radiative heating and cooling models. Even Jupiter
  with its 3-degree obliquity shows clear evidence for seasonal forcing of
  temperatures in the upper troposphere and stratosphere. The second most
  prominent characteristic of the resolvable polar temperature fields in
  Jupiter and Saturn is the formation of polar vortices. Jupiter's polar
  vortices are cold, similar to those detected in the terrestrial planets;
  they have sharp equatorward boundaries which are characterized by Rossby
  waves which rotate at the speed of the local zonal wind flow and are
  coincident with the similarly irregular boundaries of a polar haze, also
  known as "polar hoods". The cold vortex at Saturn's northern winter pole
  is muted, but Saturn also has a unique "warm polar vortex" in the south
  (late summer) pole which shows no apparent wave structure. Saturn's
  warm polar vortex has no counterpart in the Earth's atmosphere,
  where summer radiative warming simply dissipates the cold winter
  vortex. Saturn also possesses dynamically driven hot regions within
  2 degrees of its poles where dynamics is driving relatively dry air
  downwards, causing adiabatic warming and clearing the atmosphere; this
  phenomenon also has no terrestrial counterpart. Jupiter's upper polar
  stratosphere is warmed in discrete local regions by Joule heating from
  energetic particles cascading into the neutral atmosphere. The northern
  auroral-related polar "hot spot" has a very predictable geometry,
  but an amplitude that is variable over time scales of months. On
  the other hand, the stratosphere 25-30 degrees from Neptune's pole
  shows signs of ephemeral hot spots which are more likely to related
  to dynamics. These phenomena provide a rich basis of constraints for
  global climate models which must, at least for Jupiter, be coupled
  with models of auroral energy transport.

---------------------------------------------------------
Title: A General Radiative Seasonal Climate Model Applied to Saturn,
    Uranus, and Neptune.
Authors: Greathouse, T. K.; Strong, S.; Moses, J.; Orton, G.; Fletcher,
   L.; Dowling, T.
2008AGUFM.P21B..06G    Altcode:
  With similar compositions, a range of planet-sun distances, different
  orbital periods, and a variety of axial tilts, the Giant Planets are
  a unique test set for seasonal climate variation studies. We have
  created a general radiative seasonal climate model in an attempt to
  reproduce observed and predict future stratospheric temperatures of the
  Giant Planets. We present here a description of the radiative heating
  and cooling algorithms used in calculating the change in temperature
  with time. We will discuss the methods used to decrease run time,
  the opacity tables used, and indicate where more detailed opacity
  information would prove useful. We will use Saturn seasonal models to
  show the impact variations of the key coolants, acetylene and ethane,
  and the dominant heaters, methane and aerosols, have on predicted
  stratospheric temperatures. We will also present the initial results
  from the application of our model to the atmospheres of Uranus and
  Neptune. The same planet independent heating/cooling code implemented
  in our radiative seasonal climate model is being incorporated into
  the global circulation model EPIC. This work was funded by NASA PATM
  grants NNX08AE64G and NNX08AL95G.

---------------------------------------------------------
Title: Spatial and Temporal Relationships Between WL/UV Continuum
    and hard X-ray Footpoints in Solar Flares
Authors: Hudson, H. S.; Fletcher, L.; McTiernan, J.
2008AGUFMSH41A1605H    Altcode:
  Hard X-rays show the presence of energetic electrons in the
  impulsive phase of a solar flare. According to standard models, these
  electrons contain a large fraction of the total flare energy. We
  show that comparable amounts of energy are present in the compact,
  rapidly variable WL and UV bright points that constitute white-light
  flares. This suggests that these structures can be identified with
  each other, and indeed the image centroids and time variations match
  well. There are image differences that we believe mainly to be due to
  the different resolving powers of Hinode and TRACE WL/UV imaging on the
  one hand, and RHESSI hard X-rays on the other. We therefore also use
  RHESSI modeling software to simulate hard X-ray images using TRACE and
  Hinode data as templates to understand this relationship more precisely.

---------------------------------------------------------
Title: Saturn's South Polar Vortex Compared to Other Large Vortices
    in the Solar System
Authors: Dyudina, U. A.; Ingersoll, A. P.; Ewald, S. P.; Vasavada,
   A. R.; West, R. A.; Baines, K. H.; Momary, T. W.; Barbara, J. M.;
   Del Genio, A. D.; Porco, C. C.; Achterberg, R. K.; Flasar, F.;
   Simon-Miller, A. A.; Fletcher, L. N.
2008AGUFM.P11C1283D    Altcode:
  Observations made by the Imaging Science Subsystem (ISS), Visible
  and In- frared Mapping Spectrometer (VIMS) and the long-wavelength
  Composite Infrared Spectrometer (CIRS) aboard the Cassini spacecraft
  reveal that the large, long-lived cyclonic vortex at Saturn's south
  pole has a 4200-km-diameter cloud-free nearly circular region. This
  region has a 4 K warm core extending from the troposphere into the
  stratosphere, concentric cloud walls extending 20-70 km above the
  internal clouds, and numerous external clouds whose an- ticyclonic
  vorticity suggests a convective origin. The rotation speeds of the
  vortex reach 150-190 m/s, and may strengthen with depth. The Saturn
  polar vortex has features in common with terrestrial hurricanes and
  with the Venus polar vortex. Neptune and other giant planets may also
  have strong polar vortices.

---------------------------------------------------------
Title: Deuterium in the Outer Planets: New Constraints and New
    Questions from Infrared Spectroscopy
Authors: Fletcher, L. N.; Orton, G. S.; Mainzer, A.; Line, M. R.;
   Merlet, C.; Burgdorf, M.; Irwin, P. G.
2008AGUFM.P21B..04F    Altcode:
  We discuss how new observations of far-infrared rotational lines of
  HD and mid-infrared vibrational features of CH3D are challenging the
  accepted measurements for the deuterium abundance in the outer solar
  system. New derivations of D/H will be presented from the Cassini
  Composite Infrared Spectrometer (CIRS) for Saturn, the Spitzer Infrared
  Spectrometer (IRS) for Uranus and Neptune and the grism mode of the
  AKARI Infrared camera (IRC) for Neptune. Many thousands of spatially
  resolved Cassini/CIRS spectra at an unapodized spectral resolution of
  0.25 cm-1 covering a variety of latitudes on Saturn have been acquired
  during Cassini's prime mission, and are coadded to give ten independent
  estimates of the HD mole fraction and hundreds of estimates of the
  CH3D mole fraction. Spitzer/IRS acquired disc-averaged spectra of
  Uranus during Cycle 1 and more recently with Director Discretionary
  time in December 2007. Neptune disc-averaged spectra were acquired
  during Cycle 2 (November 2005). ISAS/JAXA's AKARI satellite recorded
  disc-integrated spectra of Neptune in May 2007 with a resolving
  power of 50 in the 5.5-13 micron range. These spectra have been
  analysed using two separated radiative transfer and retrieval models
  to check for consistency of results. On Saturn, we retrieve lower
  estimates of D/H from HD and CH3D than were obtained from ISO/SWS
  by Lellouch et al. (2001). Preliminary analysis of Uranus spectra
  suggest that the CH3D/CH4 ratio is significantly smaller than that
  predicted by the HD abundance determined from ISO/SWS by Feuchtgruber
  et al. (1999), suggesting a Uranian ratio more like that of Saturn,
  or a substantially different fractionation factor from that in the
  current literature. Furthermore, although constraints on CH3D from
  mid-IR Neptune spectroscopy are weaker, preliminary findings are that
  the CH3D/CH4 ratio is lower than that obtained by Orton et al. (1992)
  and inferred from HD measurements from ISO/SWS (Feuchtgruber et al.,
  1999). Fletcher is supported by an appointment to the NASA Postdoctoral
  Program at the Caltech/Jet Propulsion Laboratory, administered by Oak
  Ride Associated Universities through a contract with NASA.

---------------------------------------------------------
Title: Saturn and Jupiter: Surprising Similarities and Stark
    Differences in Dynamics and Chemistry in the Gas Giants as Revealed
    by Galileo, Cassini, and New Horizons
Authors: Baines, K. H.; Fletcher, L. N.; Momary, T. W.; West, R. A.;
   Atreya, S. K.; Brown, R. H.; Showman, A. P.; Simon-Miller, A. A.
2008AGUFM.P21B..05B    Altcode:
  Imagery and spectra obtained by a variety of spacecraft over the
  past decade have revealed much about the atmospheres of the two gas
  giants. A partial listing of salient phenomena documented by these
  spacecraft on both planets include aurorae, lightning, the 3-D nature
  of zonal winds, thunderstorm-related clouds, spectrally-identifiable
  ammonia clouds, wave features, and long-lived discrete features at
  mid-latitudes and near the poles. Temporal variability in regional
  cloud structures are observed - seasonally on Saturn, more episodically
  on Jupiter. Molecular abundances of disequilibrium gases also vary
  spatially on both planets. These and other relevant phenomena will
  be discussed in this talk comparing the dynamics and chemistry of the
  two gas giants of our solar system.

---------------------------------------------------------
Title: Correlative Analysis of the Interaction of a Large Red
Oval with the Great Red Spot and Oval BA in May - August 2008:
    Local Meteorology
Authors: Yanamandra-Fisher, P. A.; Orton, G. S.; Fletcher, L. N.;
   Simon-Miller, A.
2008AGUFM.P11A1257Y    Altcode:
  We acquired visible, near- and mid-infrared observations via a
  coordinated global campaign to observe the close encounter between
  the Great Red Spot and Oval BA, involving Hubble Space Telescope
  (HST), NASA/InfraRed Telescope Facility (IRTF)(NSFCAM2/MIRSI),
  Telescopio Nazionale Galileo (TNG)/NICS (with adaptive optics),
  Very Large Telescope (VLT)/VISIR, NOAJ/Subaru/COMICS and UKIRT/UIST
  (with tip-tilt). Although initial results indicate that changes in the
  albedo of the visible cloud deck and thermal field in the troposphere
  recovered shortly after the passage of the large red anticyclonic oval
  between the GRS and Oval BA, at near-infrared wavelengths, changes
  in the atmosphere are still occurring (as of this writing). The
  interaction started late June 2008. The small red oval, drifting
  eastward toward the GRS, was entrained in the peripheral flow south
  of the GRS. After being squeezed between the GRS and Oval BA, the
  elongated large red oval emerged, with part of it following a spiral
  path as it was entrained in the northern flow around the GRS, while
  another portion reformed itself slightly north of its pre-interaction
  latitude, indicating that the nature of the passage may have occurred
  at higher altitudes. By 10 July 2008, remnants of the red oval were
  still recognizable as a distinct feature as high-altitude particles in
  the near infrared. The red oval and Oval BA continued to drift eastward
  of the GRS. By 27 July 2008, the GRS and Oval BA were still observable
  at as relatively bright, discrete features in the reflected sunlight,
  with only the GRS showing a bright 4.78-micron annulus. However, the
  pre-encounter 4.78-micron bright annulus of the large red oval was
  not detectable. We shall present correlative analysis of the local
  meteorology of the interaction in terms of variations of the wind
  field, spectral composition, and tropospheric properties and compare
  with similar properties prior to the current interaction.

---------------------------------------------------------
Title: Hard X-ray emission from the solar corona
Authors: Krucker, S.; Battaglia, M.; Cargill, P. J.; Fletcher, L.;
   Hudson, H. S.; MacKinnon, A. L.; Masuda, S.; Sui, L.; Tomczak, M.;
   Veronig, A. L.; Vlahos, L.; White, S. M.
2008A&ARv..16..155K    Altcode: 2008A&ARv.tmp....8K
  This review surveys hard X-ray emissions of non-thermal electrons in the
  solar corona. These electrons originate in flares and flare-related
  processes. Hard X-ray emission is the most direct diagnostic of
  electron presence in the corona, and such observations provide
  quantitative determinations of the total energy in the non-thermal
  electrons. The most intense flare emissions are generally observed
  from the chromosphere at footpoints of magnetic loops. Over the years,
  however, many observations of hard X-ray and even γ-ray emission
  directly from the corona have also been reported. These coronal sources
  are of particular interest as they occur closest to where the electron
  acceleration is thought to occur. Prior to the actual direct imaging
  observations, disk occultation was usually required to study coronal
  sources, resulting in limited physical information. Now RHESSI has
  given us a systematic view of coronal sources that combines high
  spatial and spectral resolution with broad energy coverage and high
  sensitivity. Despite the low density and hence low bremsstrahlung
  efficiency of the corona, we now detect coronal hard X-ray emissions
  from sources in all phases of solar flares. Because the physical
  conditions in such sources may differ substantially from those of
  the usual “footpoint” emission regions, we take the opportunity
  to revisit the physics of hard X-radiation and relevant theories of
  particle acceleration.

---------------------------------------------------------
Title: Impulsive Flare Energy Transport by Large-Scale Alfven Waves,
    and Flare Electron Acceleration
Authors: Fletcher, L.; Hudson, H. S.
2008ESPM...12.3.62F    Altcode:
  The impulsive phase of a solar flare marks the epoch of rapid conversion
  of energy stored in the pre-flare coronal magnetic field. Hard X-ray
  observations imply that a substantial fraction of flare energy released
  during the impulsive phase is converted to the kinetic energy of mildly
  relativistic electrons (10-100 keV). The liberation of the magnetic free
  energy can occur as the coronal magnetic field reconfigures and relaxes
  following reconnection. Motivated by observations pointing to a high
  local Alfven speed in parts of the corona, and by considerations from
  magnetospheric physics, we investigate a scenario in which products of
  the reconfiguration - large-scale Alfven wave pulses - transport the
  energy and magnetic-field changes rapidly through the corona to the
  lower atmosphere. We investigate the opportunities that such a scenario
  offers for heating of the chromospheric plasma in flare footpoints, and
  for electron acceleration, and confront our findings with observational
  constraints, including energetics, HXR timing, and radio signatures.

---------------------------------------------------------
Title: Observations of the Interaction of a Large Red Oval with
the Great Red Spot and Oval BA in May-Aug 2008: Thermal Emission
    Properties
Authors: Orton, Glenn S.; Fletcher, L. N.; Yanamandra-Fisher, P. A.;
   Mousis, O.; Van den Anck, M.; Edkins, E.; Line, M.; Fujiyoshi,
   T.; Fuse, T.; Rogers, J.; Sanchez-Lavega, A.; Simon-Miller, A.;
   Chanover, N.
2008DPS....40.5002O    Altcode: 2008BAAS...40..487O
  Thermal-infrared observations of the close passage of Jupiter's Great
  Red Spot and Oval BA serendipitously observed their interaction
  with a smaller and younger red anticyclone in late June through
  August of 2008. Filtered radiometric images were obtained at the
  NASA IRTF's MIRSI instrument at 7.85 - 24.5 microns, together with
  imaging between 8.8 and 24.5 microns and 7-14 micron spectroscopy at
  higher spatial resolution with the Subaru Telescope COMICS and the
  Very Large Telescope (Melipal) VISIR instruments over several nights
  in this time frame. The data were acquired during regularly scheduled
  observations at the IRTF and Subaru, service time at the VLT, and VLT
  target-of-opportunity observations triggered by this event. We derive
  maps of temperature structure in the 100-400 mbar range, variations of
  the para-hydrogen fraction and ammonia gas abundance near 300 mbar, and
  relative cloud opacities at the 600-mbar level and deeper. Before the
  interaction, the small red spot is clearly identified as a well-defined
  anticyclone with strongly-defined boundaries of peripheral subsidence
  and a cold and cloudy central upwelling. Drifting eastward toward the
  Great Red Spot, it was captured in the periphery of southbound flow
  around the GRS around July 1 and was recognizable over the next few
  days as a narrow, cold cloud feature, stretched around the GRS south
  periphery. The data suggest that a portion of it became entrained in
  the GRS itself and formed a very elongated and nearly spiral feature,
  while another portion remained outside the GRS and temporarily reformed
  to its east, accompanied by smaller fragments. As of this writing, the
  event is still taking place, and conclusions are tentative. Variations
  of tropospheric properties will be scrutinized and compared with prior
  conditions, as well as visible color changes and near-infrared tracking
  of upper-tropospheric particulates.

---------------------------------------------------------
Title: Investigation of Lyman &lt;alpha&gt; Emission in a Solar Flare
Authors: Rubio da Costa, F.; Fletcher, L.; Labrosse, N.; Zuccarello, F.
2008ESPM...12.2.64R    Altcode:
  The TRACE satellite observed a small number of solar flares in the
  Lyman alpha channel, which have until now not been analysed. We look at
  a well-observed flare on 8th September 1999 to investigate different
  topics. We carry out a study of the spatial and temporal evolution of
  the flare and associated filament eruption in Lyman alpha, hard X-rays
  and soft X-rays, and examine the flare energetics using the hard X-rays
  (in the collisional thick target approximation) to estimate the energy
  flux carried by electrons, and TRACE Lyman alpha/1600 Å channels to
  estimate the temperature and radiative power in UV. We will use these
  observations to anticipate what can be observed in the future by the
  proposed SMESE satellite mission, and to compare with predictions of
  semi-empirical and theoretical models of the flare chromosphere.

---------------------------------------------------------
Title: The Strongest Jet Ever Detected and a New Thermal Wave in
    Saturn's Equatorial Stratosphere
Authors: Li, Liming; Gierasch, P.; Achterberg, R.; Conrath, B.;
   Flasar, M.; Vasavada, A.; Ingersoll, A.; Banfield, D.; Simon-Miller,
   A.; Fletcher, L.
2008DPS....40.5306L    Altcode: 2008BAAS...40..495L
  The strongest stratospheric jet yet detected, with a speed between 500
  and 600 m/s, has been discovered in the equatorial region of Saturn
  by combining the nadir and limb observations of Composite Infrared
  Spectrometer (CIRS) aboard the Cassini spacecraft. A similar jet
  was discovered on Jupiter. These discoveries raise the possibility
  that intense jets are common in the equatorial stratospheres of giant
  planets. The jet's velocity is steady during the observational period
  (March, 2005 to January, 2008), but variations over a longer time-scale
  are possible and may be associated with the semi-annual oscillations
  of Saturn&amp;#226&amp;#8364&amp;#8482s low-latitude stratospheric
  temperatures. An equatorial wave with wavenumber 9 is revealed in the
  stratosphere of Saturn by the CIRS high spatial-resolution thermal
  maps. The equatorial wave has a westward phase velocity of 10-110
  m/s relative to the background current, indicating that it is an
  equatorial Rossby wave. The discovery of an equatorial wave in the
  stratosphere suggests that Saturn's equatorial oscillations may be
  driven by vertically propagating waves, the same mechanism that drives
  the quasi-biennial oscillation (QBO) on Earth.

---------------------------------------------------------
Title: Hard X-ray Emission from a Flare-related Jet
Authors: Bain, H. M.; Fletcher, L.
2008ESPM...122.102B    Altcode:
  We report the observation of hard X-ray emission which we attribute to
  a flare-related jet. The event occurred on the 22nd of August 2002 and
  its evolution was observed by a number of instruments. In particular we
  study the pre-impulsive and impulsive phase of the flare using data from
  RHESSI and the TRACE 195 passband. During this period RHESSI observes
  significant hard X-ray emission to energies as high as 50 keV in the
  jet. Estimates from RHESSI spectroscopy suggest a temperature of the
  order of approximately 20MK for this time. Radio observations from the
  Nobeyama Radioheliograph (NoRH) show a positive spectral index for the
  ejected material backing the presence of non-thermal emission. This
  also shows the jet to be optically thick at radio frequencies, possibly
  due to free-free absorption.

---------------------------------------------------------
Title: First Results of Infrared Spectroscopy of Neptune From
    AKARI IRC
Authors: Burgdorf, Martin J.; Drossart, P.; Encrenaz, T.; Fletcher,
   L. N.; Orton, G.
2008DPS....40.5009B    Altcode: 2008BAAS...40..489B
  Disk-integrated spectra of Neptune were recorded on 2007-05-13, between
  1.8 and 13 microns, using both the prism and the grism of the Infrared
  Camera on board ISAS/JAXA's AKARI satellite. The spectral resolving
  power was about 140 in the interval 2.5 - 5 microns and between 20 and
  50 at other wavelengths. As Triton was included in the field of view at
  a distance of only 6 arcsec in the cross-dispersion direction, we had
  to subtract its contribution to the near-infrared spectra. <P />From
  the mid-infrared spectra we determine the stratospheric temperature
  and the CH<SUB>4</SUB> mixing ratio. We find good agreement with
  the observations obtained with the infrared spectrometer aboard
  Spitzer on 2005-11-20, with possible differences in the measured
  emission of ethane and methane between the two observatories being
  less than 10%. In contrast to this we find in the near-infrared flux
  densities up to a factor five weaker than previous measurements,
  confirming the presence of meteorological variations. <P />At short
  wavelength, an emission peak at 4.7 microns can be interpreted as due
  to fluorescent emission of CO. A similar emission feature has been
  detected previously on Uranus (Encrenaz et al, A&amp;A, 2004). As on
  Uranus, the fluorescent dominant emission comes from CO (2-1) band,
  and fits the observed peak. The contribution from the (1-0) band is
  strongly self-absorbed, and weaker. Synthetic spectra are calculated
  from a non-LTE radiative model, including solar radiation absorption,
  self-absorption in the resonant fluorescent (1-0) band, and frequency
  redistribution from vibrational CO bands. The spectra are compared
  to constrain the vertical variation of CO abundance as measured from
  submm range (Hesman et al, Icarus, 2007), the information from the
  fluorescence emission coming from as deep as the 1 bar level.

---------------------------------------------------------
Title: Jupiter's South Equatorial Belt Outbreak Spots and the SEB
    Fade and Revival Cycle
Authors: Go, Christopher; de Pater, I.; Marcus, P.; Rogers, J.;
   Simon-MIller, A.; Wong, M.; Orton, G.; Baines, K.; Asay-Davis, X.;
   Yanamandra-Fisher, P.; Fletcher, L.
2008DPS....40.4306G    Altcode: 2008BAAS...40..475G
  Amateur planetary imagers chronicled the 2007 upheaval of Jupiter,
  providing an opportunity to observe the Fade/Revival Cycle of the
  South Equatorial Belt (SEB). When the outbreaks of convective white
  spots in the SEB stopped, the SEB faded and the wake of the GRS
  disappeared. When an outbreak appeared, the SEB revival occurred--and
  the GRS wake became turbulent once more. The distinctive dark red
  color of the SEB is also associated with material brought up by SEB
  outbreaks. <P />This poster will show the SEB Fade and Revival cycle
  and how the SEB Outbreak plays a role in this cycle from images from
  various amateur astronomers, along with images from the Hubble Space
  Telescope, ground based observatories and various spacecraft.

---------------------------------------------------------
Title: Saturn's North Polar Vortex Revealed by Cassini/VIMS: Zonal
    Wind Structure and Constraints on Cloud Distributions
Authors: Baines, Kevin H.; Momary, T. W.; Fletcher, L. N.; Buratti,
   B. J.; Roos-Serote, M.; Showman, A. P.; Brown, R. H.; Clark, R. N.;
   Nicholson, P. D.
2008DPS....40.5309B    Altcode: 2008BAAS...40..495B
  We present the first high-spatial resolution, near-nadir imagery and
  movies of Saturn's north polar region that reveal the wind structure
  of a north polar vortex. Obtained by Cassini/VIMS on June 15, 2008
  from high over Saturn's polar region (sub-spacecraft latitude of
  65 degrees N. lat) at an altitude of 0.42 million km during the long
  polar night, these 210-per-pixel images of the polar region north of 73
  degrees N. latitude show several concentric cloud rings and hundreds
  of individual cloud features in silhouette against the 5-micron
  background thermal glow of Saturn's deep atmosphere. In contrast to
  the clear eye of the south polar vortex, the north polar vortex sports
  a central cloud feature about 650-km in diameter. Zonal winds reach
  a maximum of 150 m/s near 88 degrees N. latitude (planetocentric)
  - comparable to the south polar vortex maximum of 190 m/s near 88
  degrees S. latitude - and fall off nearly monotonically to 10 m/s near
  80 degrees N. latitude. At slightly greater distance from the pole,
  inside the north polar hexagon in the 75-77 degree N. latitude region,
  zonal winds increase dramatically to 130 m/s, as silhouetted clouds are
  seen speeding aroud the "race track” of the hexagonal feature. VIMS
  5-micron thermal observations over a 1.6-year period from October 29,
  2006 to June 15, 2008 are consistent with the polar hexagon structure
  itself remaining fixed in the Voyager-era radio rotation rate (Desch
  and Kaiser, Geophys. Res. Lett, 8, 253-256, 1981) to within an accuracy
  of 3 seconds per rotational period. This agrees with the stationary
  nature of the wave in this rotation system found by Godfrey (Icarus 76,
  335-356, 1988), but is inconsistent with rotation rates found during
  the current Cassini era.

---------------------------------------------------------
Title: The Pre-flare Phase: Key to Understanding Energy and Mass
    Transport in Flare Loops
Authors: Battaglia, M.; Fletcher, L.; Benz, A. O.
2008ESPM...12.2.85B    Altcode:
  In the classical solar flare scenario, the chromosphere is heated by an
  incident beam of supra-thermal electrons that were accelerated in the
  corona, then precipitated downward along the field lines of a magnetic
  loop. The hot chromospheric plasma expands and fills the magnetic
  loops. This process has been termed chromospheric evaporation. The
  classical scenario causes characteristic emission in soft- and hard
  X-rays, both from the corona and the chromosphere. The time evolution of
  this emission follows a specific pattern known as the Neupert effect. <P
  />Recent observations indicate that this scenario is only applicable for
  about half of the observed flares (Veronig et al. 2002). The early rise
  phase of many events is dominated by increasing soft X-ray emission up
  to minutes before the onset of the hard X-ray emission. This pre-heating
  clearly contradicts the classical Neupert scenario and indicates that
  other mechanisms of energy transport such as thermal conduction have
  to be at work. It also implies that the pre-flare energy release is
  dominated by heating, not acceleration. While energy transport by
  thermal conduction and subsequent chromospheric evaporation has been
  studied in some detail for the decay phase of solar flares, we present
  the first comprehensive study of the early phases of 4 pre-heating
  events. We analyze the time evolution of those events in imaging and
  spectroscopy using data from the RHESSI satellite and demonstrate how
  this can improve our understanding of heating and evaporation processes
  in coronal loops and the initiation of particle acceleration.

---------------------------------------------------------
Title: Saturn's Dynamic Atmosphere at Depth: Physical Characteristics
    and Zonal Winds Derived from Clouds Near the 2-bar Level and Their
    Dynamical Implications from Cassini-Huygens/VIMS
Authors: Momary, Thomas W.; Baines, K. H.; Fletcher, L. N.; Kim, J. H.;
   Buratti, B. J.; Roos-Serote, M.; Showman, A. P.; Brown, R. H.; Clark,
   R. N.; Nicholson, P. D.; Cassini/VIMS Science Team
2008DPS....40.4113M    Altcode: 2008BAAS...40..472M
  A wide variety of cloud structures - comprised, putatively, of ammonia
  and ammonia hydrosulfide , but perhaps with an admixture of water - has
  been characterized by Cassini/VIMS, including dozens of axisymmetric
  zonal features, planetary waves, classic vortex structures at both
  the north and south poles, and a hexagonal slow-speed wave feature
  centered on the north pole. At depth, the axisymmetric zonal features
  average just 1.7 degrees in latitudinal width, less than half of
  that at the 0.05- and 0.5-bar levels observed in reflected sunlight,
  suggesting that either (1) the patterns of ascending/descending motion
  have smaller latitudinal length scales at &gt; 1.3 bar than at shallower
  levels, and/or (2) horizontal mixing is better able to "smooth out" the
  cloud structure at shallow levels than at depth. Numerous long-lived
  (&gt; 1.5-years) discrete cloud structures have been observed in the
  northern hemisphere, including annular ("donut") clouds near 49 and
  57 degrees north latitude (planetocentric) and a "string of pearls”
  of some two-dozen similarly sized ( 1500 km diameter) cloud-clearings
  nearly uniformly spaced across 100 degrees of longitude near 33.5
  degrees latitude. The "string of pearls” and the mid-latitude annular
  cloud exhibit the fastest retrograde speeds on Saturn (in the Voyager
  rotational frame). In the south, the fastest retrograde jet correlates
  with the only thunderstorm-associated clouds observed on Saturn. VIMS
  daytime spectra indicate that two kinds of clouds predominate there:
  spectrally bright and spectrally dark. The bright clouds are the
  first spectrally-identified ammonia clouds on Saturn, presumably
  formed by ammonia-laden air propelled upward by thunderstorm-related
  convection originating &gt; 75 km below. Thus both vertically-extensive
  (thunderstorms) and long-lived, coherent cloud features ("pearls” and
  "donuts") correlate well with retrograde motions, perhaps indicating
  unusually low vertical shears there which preserve coherency and allow
  convective flows to rise relatively unimpeded over large vertical
  distances.

---------------------------------------------------------
Title: Energy Release and Transport in Solar Flares: Three-Dimensional
    MHD Simulations
Authors: Birn, J.; Birn, J.; Fletcher, L.; Hesse, M.; Neukirch, T.
2008ESPM...12.3.33B    Altcode:
  Using three-dimensional magnetohydrodynamic (MHD) simulations,
  we investigate energy release and transfer in a three-dimensional
  extension of the standard two-ribbon flare picture. In this scenario
  reconnection is initiated in a thin current sheet (suggested to form
  below a departing coronal mass ejection) above a bipolar magnetic
  field. Two cases are contrasted: an initially force-free current sheet
  (low beta) and a finite-pressure current sheet (high beta). The energy
  conversion process from reconnection consists of incoming Poynting flux
  (from the release of magnetic energy) turned into up- and downgoing
  Poynting flux, enthalpy flux and bulk kinetic energy flux. In the
  low-beta case, the outgoing Poynting flux is the dominant contribution,
  whereas the outgoing enthalpy flux dominates in the high-beta case. The
  bulk kinetic energy flux is only a minor contribution, particularly
  in the downward direction. The dominance of the downgoing Poynting
  flux in the low-beta case, which may be seen as an Alfvenic pulse, is
  consistent with an alternative to the thick target electron beam model
  for solar flare energy transport, suggested recently by Fletcher and
  Hudson. For plausible characteristic parameters of the reconnecting
  field configuration, we obtain energy release time scales and and
  energy output rates that compare favorably with those inferred from
  observations for the impulsive phase of flares.

---------------------------------------------------------
Title: The Continuing Evolution of the Interaction of a Large Red
Oval with the Great Red Spot and Oval BA in May - August 2008:
    Near-Infrared Properties
Authors: Yanamandra-Fisher, Padma A.; Orton, G. S.; Fletcher, L. N.;
   Tanga, P.; Cecconi, M.; Adamoli, G.; Irwin, P.; Holt, D.; Grimes,
   H.; Edkins, E.; Brookhart, M.; Adamson, A.
2008DPS....40.4103Y    Altcode: 2008BAAS...40..469Y
  We acquired near- and mid-infrared observations via a coordinated
  global campaign to observe the close encounter between the Great
  Red Spot and Oval BA, involving NASA/InfraRed Telescope Facility
  (IRTF)(NSFCAM2/MIRSI), Telescopio Nazionale Galileo (TNG)/NICS (with
  adaptive optics), Very Large Telescope (VLT)/VISIR, NOAJ/Subaru/COMICS
  and UKIRT/UIST (with tip-tilt). We focus on near-infrared observations
  where the longest-lasting changes to the atmosphere occurred and report
  on the evolution of a large red anticyclonic vortex that passed between
  them because of the unexpected nature of the event. The interaction
  started late June 2008. After being squeezed between the much larger
  GRS and Oval BA 1-3 July 2008, the large red oval emerged slightly
  north of its pre-interaction latitude, indicating that the nature of
  the passage may have occurred at higher altitudes. By 10 July 2008,
  remnants of the red oval were still recognizable as a distinct feature
  as high-altitude particles in the near infrared. The red oval and Oval
  BA continued to drift eastward of the GRS. Some peripheral material from
  the red oval appeared to have become entrained around the GRS northern
  boundary. By 27 July 2008, the GRS and Oval BA were still observable
  at as relatively bright, discrete features in the reflected sunlight,
  with only the GRS showing a bright 4.78-micron annulus. However, the
  pre-encounter 4.78-micron bright annulus of the large red oval was not
  detectable. In reflected sunlight from upper-atmospheric particulates,
  the large red oval had evolved into a main core, accompanied by a number
  of small discrete features, quasi-evenly located between the main core
  and the northeast quadrant of the GRS. The GRS-Oval BA-large red oval
  complex continues to evolve in the near-infrared. As of this writing,
  we continue to acquire further observations of the three-oval complex.

---------------------------------------------------------
Title: Spitzer IRS Analysis of Neptune
Authors: Line, Michael R.; Orton, G. S.; Fletcher, L. N.; Mahmud,
   A.; Moses, J. I.; Mainzer, A. K.; Yung, Y. L.
2008DPS....40.4203L    Altcode: 2008BAAS...40..473L
  Recent (2005) Spitzer Infrared Spectrometer (IRS) data of Neptune
  between 5 and 20 um contain a wealth of information about the chemical
  composition and temperature structure of its cold atmospheres. Emission
  features in its spectrum arise from many hydrocarbons, including
  ethane, acetylene and methane, and they appear to be superimposed
  on top of a collision-induced H2 continuum. As the derivation of all
  other parameters depends on the assumed temperature profile, special
  efforts were taken to ensure that the stratospheric profile between 1
  bar and 0.3 mbar matched the H2 continuum and the H2 S(1) quadrupole
  feature at 17 um. Additionally we matched the methane v4 feature at
  7.7 um in order to constrain the stratospheric temperature profile
  above the 0.3-mbar level as well as the methane stratospheric volume
  mixing ratios (VMRs). After the determination of the temperature
  profile and methane VMRs, the VMRs for several species were then
  determined through fitting their corresponding features in the spectrum,
  initially by scaling existing photochemical models (see Mahmud et al.,
  this conference). These species include methylacetylene, diacetylene,
  benzene, acetylene, ethane, methyl radical, ethylene and carbon dioxide
  which are all derived from methane photochemistry. <P />I would like
  to acknowledge the NASA USRP program for supporting this work.

---------------------------------------------------------
Title: Solar Flare Impulsive-phase Footpoints in Extreme UV, Soft
    X-Rays and Hard X-Rays
Authors: Bain, H. M.; Fletcher, L.
2008ASPC..397..157B    Altcode:
  We examine the flare of 14 March 2002, which has early impulsive phase
  TRACE 171 Å channel EUV footpoints co-spatial with RHESSI foopoints
  at energies between 6 and 50 keV. Surprisingly, the HXR spectrum from
  these footpoint sources at this time is clearly thermal, consistent
  with plasma temperatures up to 30 MK. The evidence points to impulsive
  thermal footpoint emission, such as was observed previously with the
  Yohkoh Soft X-ray Telescope, implying that the upper chromosphere or
  transition region plasma is heated rapidly to temperatures of millions
  of degrees.

---------------------------------------------------------
Title: A Testbed for Advanced Cold Curation of Astromaterials
Authors: Fletcher, L. A.; Bastien, R.; Allen, C. C.
2008M&PSA..43.5066F    Altcode:
  No abstract at ADS

---------------------------------------------------------
Title: Changing Characteristics of Jupiter's Little Red SPOT
Authors: Cheng, A. F.; Simon-Miller, A. A.; Weaver, H. A.; Baines,
   K. H.; Orton, G. S.; Yanamandra-Fisher, P. A.; Mousis, O.; Pantin,
   E.; Vanzi, L.; Fletcher, L. N.; Spencer, J. R.; Stern, S. A.; Clarke,
   J. T.; Mutchler, M. J.; Noll, K. S.
2008AJ....135.2446C    Altcode:
  The Little Red Spot (LRS) in Jupiter's atmosphere was investigated in
  unprecedented detail by the New Horizons spacecraft together with the
  Hubble Space Telescope (HST) and the Very Large Telescope (VLT). The LRS
  and the larger Great Red Spot (GRS) of Jupiter are the largest known
  atmospheric storms in the solar system. Originally a white oval, the
  LRS formed from the mergers of three smaller storms in 1998 and 2000,
  and became as red as the GRS between 2005 and 2006. Here we show that
  circulation and wind speeds in the LRS have increased substantially
  since the Voyager and Galileo eras when the oval was white. The maximum
  tangential velocity of the LRS is now 172 ± 18 m s<SUP>-1</SUP>, close
  to the highest values ever seen in the GRS, which has also evolved both
  in size and maximum wind speed. The cloud-top altitudes of the GRS and
  LRS are similar, both storms extending much higher in the atmosphere
  than other Jovian anti-cyclonic systems. The similarities in wind
  speeds, cloud morphology, and coloring suggest a common dynamical
  mechanism explaining the reddening of the two largest anticyclonic
  systems on Jupiter. These storms will not be observed again from close
  range until at least 2016.

---------------------------------------------------------
Title: The role of large-scale Alfvén waves in solar flare energy
    release and particle acceleration
Authors: Fletcher, L.; Hudson, H. S.
2008AGUSMSH51C..06F    Altcode:
  The impulsive phase of a solar flare marks the epoch of rapid conversion
  of energy stored in the pre-flare coronal magnetic field. Hard X-ray
  observations imply that a substantial fraction of flare energy
  released during the impulsive phase is converted to the kinetic
  energy of mildly relativistic electrons (10-100 keV). The liberation
  of the magnetic free energy can occur as the coronal magnetic field
  reconfigures and relaxes following reconnection. We investigate
  a scenario, inspired in part by magnetospheric physics, in which
  products of the reconfiguration - large-scale Alfvén wave pulses
  - transport the energy and magnetic-field changes rapidly through
  the corona to the lower atmosphere. This offers two possibilities
  for electron acceleration. Firstly, in a coronal plasma with E &lt;
  me/mp, the waves propagate as inertial Alfvén waves. In the presence
  of strong spatial gradients, these generate field-aligned electric
  fields that can accelerate electrons to energies on the order of 10
  keV and above, including by repeated interactions between electrons
  and wavefronts. Secondly, when they reflect in the chromosphere,
  a cascade to high wave numbers may develop. This will also accelerate
  electrons by turbulence, in a medium with a locally high electron number
  density. This concept, which bridges MHD-based and particle- based
  views of a flare, provides an interpretation of the recently-observed
  rapid variations of the line-of-sight component of the photospheric
  magnetic field across the flare impulsive phase, and offers solutions
  to some perplexing flare problems, such as the flare "number problem" of
  finding and resupplying sufficient electrons to explain impulsive-phase
  hard X-ray emission.

---------------------------------------------------------
Title: The NEMESIS planetary atmosphere radiative transfer and
    retrieval tool
Authors: Irwin, P. G. J.; Teanby, N. A.; de Kok, R.; Fletcher, L. N.;
   Howett, C. J. A.; Tsang, C. C. C.; Wilson, C. F.; Calcutt, S. B.;
   Nixon, C. A.; Parrish, P. D.
2008JQSRT.109.1136I    Altcode:
  No abstract at ADS

---------------------------------------------------------
Title: Impulsive Phase Flare Energy Transport by Large-Scale Alfvén
    Waves and the Electron Acceleration Problem
Authors: Fletcher, L.; Hudson, H. S.
2008ApJ...675.1645F    Altcode: 2007arXiv0712.3452F
  The impulsive phase of a solar flare marks the epoch of rapid conversion
  of energy stored in the preflare coronal magnetic field. Hard X-ray
  observations imply that a substantial fraction of flare energy released
  during the impulsive phase is converted to the kinetic energy of mildly
  relativistic electrons (10-100 keV). The liberation of the magnetic free
  energy can occur as the coronal magnetic field reconfigures and relaxes
  following reconnection. We investigate a scenario in which products
  of the reconfiguration—large-scale Alfvén wave pulses—transport
  the energy and the magnetic field changes rapidly through the
  corona to the lower atmosphere. This offers two possibilities
  for electron acceleration. First, in a coronal plasma with β &lt;
  m<SUB>e</SUB>/m<SUB>p</SUB>, the waves propagate as inertial Alfvén
  waves. In the presence of strong spatial gradients, these generate
  field-aligned electric fields that can accelerate electrons to energies
  on the order of 10 keV and above, including by repeated interactions
  between electrons and wave fronts. Second, when they reflect and
  mode-convert in the chromosphere, a cascade to high wavenumbers
  may develop. This will also accelerate electrons by turbulence, in
  a medium with a locally high electron number density. This concept,
  which bridges MHD-based and particle-based views of a flare, provides
  an interpretation of the recently observed rapid variations of the
  line-of-sight component of the photospheric magnetic field across the
  flare impulsive phase, and offers solutions to some perplexing flare
  problems, such as the flare "number problem" of finding and resupplying
  sufficient electrons to explain the impulsive-phase hard X-ray emission.

---------------------------------------------------------
Title: Atacama Desert Mudflow as an Analog for Recent Gully Activity
    on Mars
Authors: Heldmann, J. L.; Conley, C.; Brown, A. J.; Fletcher, L.;
   Bishop, J. L.; McKay, C. P.
2008LPI....39.2214H    Altcode:
  We discuss light-toned gully deposits in the Atacama Desert that share
  similar morphologic and spectral signatures with the new Mars gully
  deposits. We suggest that, similar to the Atacama deposits, the Mars
  gully features may be remnant mudflows.

---------------------------------------------------------
Title: Curation of Frozen Samples
Authors: Fletcher, L. A.; Allen, C. C.; Bastien, R.
2008LPI....39.2202F    Altcode:
  We discuss the design, installation, and testing of a cold glovebox
  system to be used for the curation of future frozen samples.

---------------------------------------------------------
Title: Global and temporal variations in hydrocarbons and nitriles
    in Titan's stratosphere for northern winter observed by Cassini/CIRS
Authors: Teanby, N. A.; Irwin, P. G. J.; de Kok, R.; Nixon, C. A.;
   Coustenis, A.; Royer, E.; Calcutt, S. B.; Bowles, N. E.; Fletcher,
   L.; Howett, C.; Taylor, F. W.
2008Icar..193..595T    Altcode:
  Mid-infrared spectra measured by Cassini's Composite InfraRed
  Spectrometer (CIRS) between July 2004 and January 2007 ( L=293°-328°)
  have been used to determine stratospheric temperature and abundances
  of C <SUB>2</SUB>H <SUB>2</SUB>, C <SUB>3</SUB>H <SUB>4</SUB>, C
  <SUB>4</SUB>H <SUB>2</SUB>, HCN, and HC <SUB>3</SUB>N. Over 65,000 nadir
  spectra with spectral resolutions of 0.5 and 2.5 cm <SUP>-1</SUP> were
  used to probe spatial and temporal composition variations in Titan's
  stratosphere. Cassini's 180° orbital transfer in mid-2006 allowed
  low emission angle observations of the north polar region for the
  first time in the mission and allowed us to probe the full latitude
  range. We present the first measurements of composition variations
  within the polar vortex, which display increasing abundances right
  up to 90° N. The lack of a homogeneous abundance-latitude variation
  within the vortex indicates limited horizontal mixing and suggests
  that subsidence is greatest at the vortex core. Contrary to numerical
  model predictions and tropospheric cloud observations, we do not see
  any evidence for a secondary circulation cell near the south pole,
  which suggests a single Hadley-type circulation in the stratosphere at
  this epoch. This difference can be reconciled if the secondary cell is
  restricted to altitudes below 100 km, where there is no sensitivity
  in our data. Temporal variations in composition were observed in the
  south, with volatile species becoming less abundant as the season
  progressed. The observed variations are compared to numerical model
  predictions and observations from Voyager.

---------------------------------------------------------
Title: Depth of a strong jovian jet from a planetary-scale disturbance
    driven by storms
Authors: Sánchez-Lavega, A.; Orton, G. S.; Hueso, R.; García-Melendo,
   E.; Pérez-Hoyos, S.; Simon-Miller, A.; Rojas, J. F.; Gómez,
   J. M.; Yanamandra-Fisher, P.; Fletcher, L.; Joels, J.; Kemerer, J.;
   Hora, J.; Karkoschka, E.; de Pater, I.; Wong, M. H.; Marcus, P. S.;
   Pinilla-Alonso, N.; Carvalho, F.; Go, C.; Parker, D.; Salway, M.;
   Valimberti, M.; Wesley, A.; Pujic, Z.
2008Natur.451.1022S    Altcode:
  No abstract at ADS

---------------------------------------------------------
Title: Invisible sunspots and rate of solar magnetic flux emergence
Authors: Dalla, S.; Fletcher, L.; Walton, N. A.
2008A&A...479L...1D    Altcode: 2008arXiv0801.0703D
  Aims:We study the visibility of sunspots and its influence on observed
  values of sunspot region parameters. <BR />Methods: We use Virtual
  Observatory tools provided by AstroGrid to analyse a sample of 6862
  sunspot regions. By studying the distributions of locations where
  sunspots were first and last observed on the solar disk, we derive the
  visibility function of sunspots, the rate of magnetic flux emergence
  and the ratio between the durations of growth and decay phases of solar
  active regions. <BR />Results: We demonstrate that the visibility
  of small sunspots has a strong centre-to-limb variation, far larger
  than would be expected from geometrical (projection) effects. This
  results in a large number of young spots being invisible: 44% of new
  regions emerging in the west of the Sun go undetected. For sunspot
  regions that are detected, large differences exist between actual
  locations and times of flux emergence, and the apparent ones derived
  from sunspot data. The duration of the growth phase of solar regions
  has been, up to now, underestimated. <P />Appendix A is only available
  in electronic form at http://www.aanda.org

---------------------------------------------------------
Title: Atacama Desert Mudflow as an Analog for Recent Gully Activity
    on Mars
Authors: Heldmann, J. L.; Conley, C.; Brown, A. J.; Fletcher, L.
2008LPICo1303...44H    Altcode:
  No abstract at ADS

---------------------------------------------------------
Title: Temperature and Composition of Saturn’s Polar Hot Spots
    and Hexagon
Authors: Fletcher, L. N.; Irwin, P. G. J.; Orton, G. S.; Teanby,
   N. A.; Achterberg, R. K.; Bjoraker, G. L.; Read, P. L.; Simon-Miller,
   A. A.; Howett, C.; de Kok, R.; Bowles, N.; Calcutt, S. B.; Hesman,
   B.; Flasar, F. M.
2008Sci...319...79F    Altcode:
  Saturn’s poles exhibit an unexpected symmetry in hot, cyclonic polar
  vortices, despite huge seasonal differences in solar flux. The cores of
  both vortices are depleted in phosphine gas, probably resulting from
  subsidence of air into the troposphere. The warm cores are present
  throughout the upper troposphere and stratosphere at both poles. The
  thermal structure associated with the marked hexagonal polar jet at
  77°N has been observed for the first time. Both the warm cyclonic
  belt at 79°N and the cold anticyclonic zone at 75°N exhibit the
  hexagonal structure.

---------------------------------------------------------
Title: Depth of a strong jovian jet from a planetary-scale disturbance
    driven by storms
Authors: Sánchez-Lavega, A.; Orton, G. S.; Hueso, R.; García-Melendo,
   E.; Pérez-Hoyos, S.; Simon-Miller, A.; Rojas, J. F.; Gómez,
   J. M.; Yanamandra-Fisher, P.; Fletcher, L.; Joels, J.; Kemerer, J.;
   Hora, J.; Karkoschka, E.; de Pater, I.; Wong, M. H.; Marcus, P. S.;
   Pinilla-Alonso, N.; Carvalho, F.; Go, C.; Parker, D.; Salway, M.;
   Valimberti, M.; Wesley, A.; Pujic, Z.
2008Natur.451..437S    Altcode:
  The atmospheres of the gas giant planets (Jupiter and Saturn)
  contain jets that dominate the circulation at visible levels. The
  power source for these jets (solar radiation, internal heat, or both)
  and their vertical structure below the upper cloud are major open
  questions in the atmospheric circulation and meteorology of giant
  planets. Several observations and in situ measurements found intense
  winds at a depth of 24bar, and have been interpreted as supporting an
  internal heat source. This issue remains controversial, in part because
  of effects from the local meteorology. Here we report observations
  and modelling of two plumes in Jupiter's atmosphere that erupted at
  the same latitude as the strongest jet (23°N). The plumes reached
  a height of 30km above the surrounding clouds, moved faster than any
  other feature (169ms<SUP>-1</SUP>), and left in their wake a turbulent
  planetary-scale disturbance containing red aerosols. On the basis of
  dynamical modelling, we conclude that the data are consistent only
  with a wind that extends well below the level where solar radiation
  is deposited.

---------------------------------------------------------
Title: Impulsive Flare Energy Transport by Large-Scale Alfven Waves
    and the Electron Acceleration Problem
Authors: Fletcher, L.; Hudson, H. S.
2007AGUFMSM53B1278F    Altcode:
  In this poster, we investigate an alternative scenario for solar
  flare energy transport. Usually, the energy stored in the solar
  corona and released during a flare is thought to be transported to
  the lower atmosphere by electron beams. However, based on microwave
  observations, magnetic fields of the order of a few 100 Gauss to
  a kilogauss are measured in the corona above the core of an active
  region. This implies an Alfvén speed on the order of 0.1c, meaning
  that Alfvén wave pulses become plausible agents for transporting
  the stored energy of the flare. We investigate this scenario, and the
  opportunities it presents for both heating the lower chromosphere and
  accelerating electrons to HXR-emitting energies.

---------------------------------------------------------
Title: Observations of Jupiter Supporting the New Horizons Encounter
    and During a Period of "Global Upheaval"
Authors: Orton, G.; Baines, K.; Yanamandra-Fisher, P.; Mousis, O.;
   Vanzi, L.; Hayward, T.; De Buizer, J.; Simon-Miller, A.; Bjoraker,
   G.; Fletcher, L.; Gladstone, R.; Edkins, E.; Kemerer, J.; Sitko, M.;
   Lynch, D.
2007AGUFM.P53C..03O    Altcode:
  Observations of Jupiter were made between February and June of 2007
  to provide an expanded spectral coverage and timeline for the New
  Horizons remote-sensing of Jupiter's atmosphere. From March to May,
  two prominent vertical jets in the southern portion of Jupiter's North
  Temperate Belt (NTBs) initiated a major darkening of this region,
  and their wakes restored the darker color of the belt but not its
  bright 5-micron appearance. A brightening of the southern component
  of the dark South Equatorial Belt (SEBs) was interrupted by a series
  of vertical outbursts from which a darker material emanated in both
  directions was appeared bright at 5 microns.It also generated a series
  of anticyclonic vortices with upwelling interiors and substantial
  downwelling annuli which continue to this writing.

---------------------------------------------------------
Title: Characteristics of Titan's stratospheric aerosols and
    condensate clouds from Cassini CIRS far-infrared spectra
Authors: de Kok, R.; Irwin, P. G. J.; Teanby, N. A.; Nixon, C. A.;
   Jennings, D. E.; Fletcher, L.; Howett, C.; Calcutt, S. B.; Bowles,
   N. E.; Flasar, F. M.; Taylor, F. W.
2007Icar..191..223D    Altcode:
  Four broad spectral features were identified in far-infrared limb
  spectra from the Cassini Composite Infrared Spectrometer (CIRS), two
  of which have not been identified before. The features are broader
  than the spectral resolution, which suggests that they are caused
  by particulates in Titan's stratosphere. We derive here the spectral
  properties and variations with altitude for these four features for
  six latitudes between 65° S and 85° N. Titan's main aerosol is called
  Haze 0 here. It is present at all wavenumbers in the far-infrared and is
  found to have a fractional scale height (i.e., the aerosol density scale
  height divided by the atmospheric density scale height) between 1.5
  and 1.7 with a small increase in opacity in the north. A second feature
  around 140 cm <SUP>-1</SUP> (Haze A) has similar spatial properties to
  Haze 0, but has a smaller fractional scale height of 1.2-1.3. Both Haze
  0 and Haze A show an increase in retrieved abundance below 100 km. Two
  other features (Haze B around 220 cm <SUP>-1</SUP> and Haze C around
  190 cm <SUP>-1</SUP>) have a large maximum in their density profiles
  at 140 and 90 km, respectively. Haze B is much more abundant in the
  northern hemisphere compared to the southern hemisphere. Haze C also
  shows a large increase towards the north, but then disappears at 85° N.

---------------------------------------------------------
Title: The relative timing of supra-arcade downflows in solar flares
Authors: Khan, J. I.; Bain, H. M.; Fletcher, L.
2007A&A...475..333K    Altcode:
  Context: Supra-arcade downflows (generally dark, sunward-propagating
  features located above the bright arcade of loops in some solar flares)
  have been reported mostly during the decay phase, although some
  have also been reported during the rise phase of solar flares. <BR
  />Aims: We investigate, from a statistical point of view, the timing
  of supra-arcade downflows during the solar flare process, and thus
  determine the possible relation of supra-arcade downflows to the primary
  or secondary energy release in a flare. <BR />Methods: Yohkoh Soft
  X-ray Telescope (SXT) imaging data are examined to produce a list of
  supra-arcade downflow candidates. In many of our events supra-arcade
  downflows are not directly observed. However, the events do show
  laterally moving (or “waving”) bright rays in the supra-arcade
  fan of coronal rays which we interpret as due to dark supra-arcade
  downflows. The events are analysed in detail to determine whether the
  supra-arcade downflows (or the proxy waving coronal rays) occur during
  a) the rise and/or decay phases of the soft X-ray flare and b) the flare
  hard X-ray bursts. It is also investigated whether the supra-arcade
  downflows events show prior eruptive signatures as seen in SXT, other
  space-based coronal data, or reported in ground-based Hα images. <BR
  />Results: A substantial majority of supra-arcade downflow events show
  downflows which start during the soft X-ray flare rise phase (73%),
  occur during hard X-ray bursts (90%), and have prior eruptive signatures
  associated with them (73%). However, we find a single event (2% of the
  total) which clearly and unambiguously showed supra-arcade downflows
  starting during the soft X-ray flare decay phase. <BR />Conclusions:
  Since the majority of supra-arcade downflows occur during the rise
  phase of the soft X-ray flare and the time of hard X-ray bursts, and
  have prior eruptive signatures this suggests that they are related
  to the main flare energy release process. Furthermore, the suggested
  association of supra-arcade downflows with recently reconnected
  magnetic field lines means they may indeed be considered as evidence
  for a magnetic reconnection process. The single supra-arcade downflow
  event which unambiguously started during the decay phase of the flare
  occurred during hard X-ray bursts and thus appears to be related to
  late energy release.

---------------------------------------------------------
Title: Observations of Simultaneous Coronal Loop Shrinkage and
    Expansion during the Decay Phase of a Solar Flare
Authors: Khan, J. I.; Fletcher, L.; Nitta, N. V.
2007ASPC..369..485K    Altcode:
  We report what we believe are the first direct and unambiguous
  observations of simultaneous coronal magnetic flux loop shrinkage
  and expansion during the decay phase of a solar flare. The retracting
  and expanding loops were observed nearly face-on (i.e., with the loop
  major axis approximately orthogonal to the line of sight) in emission in
  imaging data from the Yohkoh Soft X-ray Telescope (SXT). The retracting
  loop is observed to shrink with a speed of 165±26 km s^{-1}. The
  faint outward moving loop-like feature occurred ∼200 arcsec above
  the shrinking loop during the time of the shrinking loop. We estimate
  the speed of the outward moving loop was ∼280±130 km s^{-1}. We
  interpret the shrinking loop and simultaneous outward moving loop as
  direct evidence for reconnected magnetic field lines during a flare.

---------------------------------------------------------
Title: Structure and Dynamics of the Little Red Spot on Jupiter
Authors: Cheng, Andrew F.; Simon-Miller, A.; Weaver, H. A.; Baines,
   K. H.; Orton, G. S.; Yanamandra-Fisher, P. A.; Mousis, O.; Pantin, E.;
   Vanzi, L.; Fletcher, L. N.; Spencer, J.; Stern, A.; New Horizons Team
2007DPS....39.1903C    Altcode: 2007BAAS...39..444C
  The New Horizons spacecraft obtained high resolution images of the
  Little Red Spot in Jupiter's atmosphere, during the New Horizons
  Jupiter encounter in January - March, 2007. The Little Red Spot
  is an Earth-sized storm that formed from the coalescence of three,
  60-year old, white ovals starting in 1998 and that became clearly red
  in 2006. The New Horizons observations have been combined for the
  first time with Jupiter observations from the Very Large Telescope
  array in Chile and from the Hubble Space Telescope to determine the
  three-dimensional structure and dynamics of the Little Red Spot. Within
  this cold anticyclonic oval, the peak wind speeds reach 170 m/s, and
  the vertical gradient length, from the thermal wind equation, exceeds
  90 km. Horizontal flow divergences are identified. The dynamical
  structure of the Little Red Spot is similar to that of the Great Red
  Spot. It is suggested that both spots may now persist for centuries,
  although the Little Red Spot attained its current state only recently.

---------------------------------------------------------
Title: Zonal Mean Dynamics On Saturn From Cassini And Voyager Data
Authors: Read, Peter L.; Fletcher, L. N.; Irwin, P. G.; Achterberg,
   R. K.; Conrath, B. J.; Cassini CIRS Team
2007DPS....39.3705R    Altcode: 2007BAAS...39..487R
  A high resolution global map of zonal mean zonal winds and
  potential vorticity in Saturn's upper troposphere and stratosphere
  has been constructed, assuming geostrophic thermal wind balance,
  from a combination of cloud-level winds (derived from Voyager and
  Cassini images) and profiles of temperature and molecular hydrogen
  para-fraction retrieved from measurements by the Cassini Composite
  InfraRed Spectrometer (CIRS) between October 2004 and March 2006. Away
  from the equator, the results show a clear pattern of alternating jet
  streams extending to polar latitudes, all of which are found to decay
  significantly with height between 200 and &lt;5 hPa pressure. The
  equatorial jet also exhibits strong decay with height into the lower
  stratosphere, but with evidence of some more complex structure in
  the middle and upper stratosphere. Potential vorticity profiles show
  evidence for a hyper-staircase structure, much as found on Jupiter,
  though with some intriguing differences. Like Jupiter, Saturn's zonal
  flow appears to be close to neutral stability relative to Arnol'd's
  second stability theorem. This allows an estimation of the upper
  tropospheric Rossby deformation radius as a function of latitude,
  that ranges from 2000 km at high latitudes to more than 8000 km in
  the sub-tropics. These results will be presented and discussed in the
  context of their implications for global atmospheric dynamics on Saturn
  and the other outer planets.

---------------------------------------------------------
Title: Meridional variations in stratospheric acetylene and ethane
    in the southern hemisphere of the saturnian atmosphere as determined
    from Cassini/CIRS measurements
Authors: Howett, C. J. A.; Irwin, P. G. J.; Teanby, N. A.;
   Simon-Miller, A.; Calcutt, S. B.; Fletcher, L. N.; de Kok, R.
2007Icar..190..556H    Altcode:
  These are the first results from nadir studies of meridional variations
  in the abundance of stratospheric acetylene and ethane from Cassini/CIRS
  data in the southern hemisphere of Saturn. High resolution, 0.5
  cm <SUP>-1</SUP>, CIRS data was used from three data sets taken in
  June-November 2004 and binned into 2° wide latitudinal strips to
  increase the signal-to-noise ratio. Tropospheric and stratospheric
  temperatures were initially retrieved to determine the temperature
  profile for each latitude bin. The stratospheric temperature at 2
  mbar increased by 14 K from 9° to 68° S, including a steep 4 K
  rise between 60° and 68° S. The tropospheric temperatures showed
  significantly more meridional variation than the stratospheric ones,
  the locations of which are strongly correlated to that of the zonal
  jets. Stratospheric acetylene abundance decreases steadily from 30 to
  68° S, by a factor of 1.8 at 2.0 mbar. Between 18° and 30° S the
  acetylene abundance increases at 2.0 mbar. Global values for acetylene
  have been calculated as (1.9±0.19)×10 at 2.0 mbar, (2.6±0.27)×10
  at 1.6 mbar and (3.1±0.32)×10 at 1.4 mbar. Global values for ethane
  are also determined and found to be (1.6±0.25)×10 at 0.5 mbar and
  (1.4±0.19)×10 at 1.0 mbar. Ethane abundance in the stratosphere
  increases towards the south pole by a factor of 2.5 at 2.0 mbar. The
  increase in stratospheric ethane is especially pronounced polewards
  of 60° S at 2.0 mbar. The increase of stratospheric ethane towards
  the south pole supports the presence of a meridional wind system in
  the stratosphere of Saturn.

---------------------------------------------------------
Title: The 2007 Jupiter's North Temperate Belt Disturbance:
    I. Overview and jet stream changes.
Authors: Sanchez-Lavega, Agustin; Orton, G. S.; Hueso, R.;
   Garcia-Melendo, E.; Perez-Hoyos, S.; Simon-Miller, A.; Rojas, J. F.;
   Gomez, J. M.; Yanamandra-Fisher, P. A.; Fletcher, L.; Joels, J.;
   Kemerer, J.; Hora, J.; Karkoschka, E.; de Pater, I.; Wong, M. H.;
   Marcus, P. S.; Pinilla, N.; International Outer Planet Watch (IOPW)
2007DPS....39.0104S    Altcode: 2007BAAS...39S.407S
  Changes in belts and zones of Jupiter are sometimes virulent, starting
  from a localized eruption followed by the development of a planetary
  scale disturbance. The archetype of this phenomenology occurs rarely,
  about once every fifteen years, at 23° North latitude where the
  highest speed Jovian jet stream resides. In late March 2007 two
  nearly simultaneous eruptions of bright plumes separated by 63,000
  km (55° longitude) occurred in the peak of the jet, causing a new
  disturbance. Here we present detailed observations of the disturbance
  onset and evolution, and of the related changes and deep extent of the
  jet based on Hubble Space Telescope images and ground-based observations
  in the visible and near infrared. The plumes reached a height elevation
  of 30 km relative to background clouds and, moving faster eastward
  than any other feature in the planet at about 165 m/s, generated a
  turbulent and complex periodic pattern in their wake, injecting a
  large amount of red aerosols. Only small changes were detected in
  the jet wind velocity profile as measured before the disturbance and
  after its dissipation. Radiative transfer of cloud vertical structure,
  mesoscale models of the plumes and a general circulation model of the
  turbulent pattern require the jet stream to be robust extending down
  to at least 5-7 bar pressure, the base of the water clouds, well below
  the sunlight penetration level. <P />Acknowledgments: this work was
  supported by the Spanish MEC-PNAYA. We acknowledge the HST director's
  discretionary time (GO/DD11310) for June 5 observations. And GO/DD10782
  for March 08 and May 11 data.

---------------------------------------------------------
Title: Spaceward Bound: Field Training for the Next Generation of
    Space Explorers
Authors: McKay, C. P.; Coe, L. K.; Battler, M.; Bazar, D.; Conrad,
   L.; Day, B.; Fletcher, L.; Green, R.; Heldmann, J.; Muscatello, T.;
   Rask, J. C.; Smith, H.; Sun, H.; Zubrin, R.
2007LPICo1371.3028M    Altcode: 2007eelo.work.3028M
  No abstract at ADS

---------------------------------------------------------
Title: Observations of Jupiter Supporting the New Horizons Encounter
    and During a Period of "Global Upheaval"
Authors: Orton, Glenn S.; Yanamandra-Fisher, P. A.; Baines, K. H.;
   Momary, T.; Mousis, O.; Vanzi, L.; Hayward, T.; DeBuizer, J.;
   Simon-Miller, A.; Bjoraker, G.; Fletcher, L.; Edkins, E.; Joels, J.;
   Kemerer, J.; Parrish, P.
2007DPS....39.0103O    Altcode: 2007BAAS...39..407O
  Multi-spectral observations of Jupiter obtained between February
  and September of 2007 provided both increased spectral support
  and an extended timeline for the New Horizons remote-sensing of
  its atmosphere. The observations also tracked a series of rapid
  changes in Jupiter's atmosphere. Data were acquired at NASA's
  Infrared Telescope Facility (MIRSI, NSFCam2 and SpeX), Gemini/South
  (T-ReCS), ESO's Very Large Telescope (VISIR) and Lick observatory
  (the Aerospace VNIRIS spectrometer). Mid-infrared observations from
  the large telescopes optimized spatial resolution in the mid-infrared
  by minimizing the effects of diffraction. In mid-February, the north
  and south auroral-generated stratospheric hot spots were resolved
  spatially, possibly for the first time; the southern one being bright
  in methane, ethylene and ethane emission. In contrast, the northern
  one was recognizable in all of these emissions, but barely above the
  background level. Subsequent observation in March and later did not
  detect any enhanced emission from the north. Observations of polar
  regions provided evidence of distinct boundaries to polar airmasses
  which coincided with the locations of high-altitude haze layers. These
  high-resolution images revealed that temperatures in the interior of
  the Great Red Spot were not elliptically symmetric but were warmer to
  the south and center of the vortex. Observations from March to June
  coincided with the initiation of several vertical jets in the southern
  portion of Jupiter's North Temperate Belt (NTBs), which precede a
  major color change in the entire belt and often signal the beginning
  of an epoch of "global upheaval" in Jupiter's cloud system with major
  disruptions to its typical appearance. Observations from May through
  this writing tracked the initiation of similar weaker jets in the
  southern portion of the South Equatorial Belt (SEBs). Our observations
  determine the altitude of these outbursts, and their influence on the
  temperature field and the distribution of para-hydrogen and ammonia.

---------------------------------------------------------
Title: Saturn's South Polar Vortex: A Possible Gas-Giant Analog to
    a Terrestrial Hurricane
Authors: Dyudina, Ulyana A.; Ingersoll, A. P.; Ewald, S. P.; Vasavada,
   A. R.; West, R. A.; Del Genio, A.; Barbara, J.; Porco, C. C.; Porco,
   C. C.; Achterberg, R. K.; Flasar, F. M.; Simon-Miller, A. A.; Fletcher,
   L. N.
2007DPS....39.3709D    Altcode: 2007BAAS...39..488D
  Observations made by the Cassini spacecraft reveal a large, long-lived
  vortex anchored to the south pole of Saturn that shares many properties
  with terrestrial hurricanes. Among these are: a central eye with
  cyclonic vorticity, an outer region where vorticity is near zero,
  a warm temperature anomaly within the eye, concentric eyewall clouds
  that extend two pressure scale heights above the clouds within the eye,
  numerous small clouds whose anticyclonic vorticity suggests a convective
  origin, and evidence, at high altitudes, of excess cyclonic rotation not
  balanced by the inward pressure force, implying outward flow. Besides
  differences of scale, the main distinctions between hurricanes on
  Earth and the one seen on Saturn are the static, polar location of
  the latter and the lack of a liquid ocean to support it. This is the
  first hurricane-like vortex detected on a planet other than Earth.

---------------------------------------------------------
Title: Condensation during Titan's Polar Winter
Authors: de Kok, Remco; Irwin, P. G.; Teanby, N. A.; Fletcher, L. N.;
   Howett, C. J.; Calcutt, S. B.; Bowles, N. E.; Taylor, F. W.
2007DPS....39.5611D    Altcode: 2007BAAS...39..530D
  Titan is currently experiencing winter in its northern hemisphere
  and the lower atmosphere of its north polar region has been in
  prolonged darkness since the solstice in October 2002. As a result,
  the north polar region is currently characterised by cold stratospheric
  temperatures and there is enrichment of trace gases due to downward
  atmospheric motion (e.g. Teanby et al., Icarus 181 pp. 243-255,
  2006). These conditions make the polar winter very suitable for
  cloud formation in the stratosphere. <P />A simple transport and
  condensation model has been made to explore condensation processes in
  Titan's northern stratosphere. In the model, the atmosphere is advected
  downwards and clouds are formed as the saturation pressure of various
  gases is reached. Upper limits of the gases C<SUB>4</SUB>N<SUB>2</SUB>
  and propionitrile (C<SUB>2</SUB>H<SUB>5</SUB>CN) were determined
  from Cassini Composite Infrared Spectrometer data to assess scenarios
  of chemical disequilibrium where the gas phase is far less abundant
  than the solid phase. The upper limit for C<SUB>4</SUB>N<SUB>2</SUB>
  is 9e-9, which discounts the massive C<SUB>4</SUB>N<SUB>2</SUB>
  build-up in the polar winter proposed by Samuelson et al. (PSS 45,
  pp. 941-948, 1997) to explain the observed C<SUB>4</SUB>N<SUB>2</SUB>
  cloud at the Voyager epoch. The propionitrile upper limit is 8e-9,
  which is several orders of magnitude less than needed to create the
  condensate feature at 220 cm<SUP>-1</SUP> of Khanna (Icarus 177,
  pp. 116-121) and de Kok et al. (Icarus, in press), assuming it is
  propionitrile ice, under the steady-state conditions explored by the
  aformentioned model. HCN ice seems to play an important role in the
  formation of a massive polar cloud (Haze B in de Kok et al., Icarus,
  in press), because of the unavailability of sufficient condensable gas
  other than HCN (and possibly HC<SUB>3</SUB>N) to produce the condensate
  features seen in far-infrared spectra at 220 cm<SUP>-1</SUP>.

---------------------------------------------------------
Title: Jovian Wind Periodicity Revisited
Authors: Tsavaris, Irene; Simon-Miller, A. A.; Orton, G. S.; Fisher,
   B.; Yanamandra-Fisher, P. A.; Parrish, P.; Fletcher, L.; Joels, J.
2007DPS....39.1906T    Altcode: 2007BAAS...39..445T
  Prior analysis of Jupiter's zonal wind field offered slight evidence
  of periodicity on short time scales, though time coverage was marginal
  (Simon-Miller et al. 2007 Icarus 186, 192-203). Though the winds are
  measured through tracking of tropospheric clouds, it was hoped that some
  relation could be found between stratospheric temperature oscillations
  (the Quasi-Quadrennial Oscillation) and tropospheric winds. However,
  complicating the analysis was the fact that the pressure levels of the
  tracked cloud features are unknown, and are spatially and temporally
  variable. Thermal wind analysis for a few of the dates showed cloud
  level variations could easily account for most of the wind speed
  variability, except at 7 deg. S latitude. New images, acquired in
  2006 and 2007, have allowed the extension of the zonal wind time base,
  improving the periodogram analysis. We will present results based on
  our newest zonal wind and temperature profiles.

---------------------------------------------------------
Title: Characterising Saturn's vertical temperature structure from
    Cassini/CIRS
Authors: Fletcher, L. N.; Irwin, P. G. J.; Teanby, N. A.; Orton, G. S.;
   Parrish, P. D.; de Kok, R.; Howett, C.; Calcutt, S. B.; Bowles, N.;
   Taylor, F. W.
2007Icar..189..457F    Altcode:
  Thermal infrared spectra of Saturn from 10-1400 cm <SUP>-1</SUP>
  at 15 cm <SUP>-1</SUP> spectral resolution and a spatial resolution
  of 1°-2° latitude have been obtained by the Cassini Composite
  Infrared Spectrometer [Flasar, F.M., and 44 colleagues, 2004. Space
  Sci. Rev. 115, 169-297]. Many thousands of spectra, acquired over
  eighteen-months of observations, are analysed using an optimal
  estimation retrieval code [Irwin, P.G.J., Parrish, P., Fouchet,
  T., Calcutt, S.B., Taylor, F.W., Simon-Miller, A.A., Nixon, C.A.,
  2004. Icarus 172, 37-49] to retrieve the temperature structure and
  para-hydrogen distribution over Saturn's northern (winter) and southern
  (summer) hemispheres. The vertical temperature structure is analysed
  in detail to study seasonal asymmetries in the tropopause height
  (65-90 mbar), the location of the radiative-convective boundary
  (350-500 mbar), and the variation with latitude of a temperature knee
  (between 150 and 300 mbar) which was first observed in inversions of
  Voyager/IRIS spectra [Hanel, R., and 15 colleagues, 1981. Science 212,
  192-200; Hanel, R., Conrath, B., Flasar, F.M., Kunde, V., Maguire,
  W., Pearl, J.C., Pirraglia, J., Samuelson, R., Cruikshank, D.P.,
  Gautier, D., Gierasch, P.J., Horn, L., Ponnamperuma, C., 1982. Science
  215, 544-548]. Uncertainties due to both the modelling of spectral
  absorptions (collision-induced absorption coefficients, tropospheric
  hazes, helium abundance) and the nature of our retrieval algorithm are
  quantified. Temperatures in the stratosphere near 1 mbar show a 25-30
  K temperature difference between the north pole and south pole. This
  asymmetry becomes less pronounced with depth as the radiative time
  constant for the atmospheric response increases at deeper pressure
  levels. Hemispherically-symmetric small-scale temperature structures
  associated with zonal winds are superimposed onto the temperature
  asymmetry for pressures greater than 100 mbar. The para-hydrogen
  fraction in the 100-400 mbar range is greater than equilibrium
  predictions for the southern hemisphere and parts of the northern
  hemisphere, and less than equilibrium predictions polewards of 40°
  N. The temperature knee between 150-300 mbar is larger in the summer
  hemisphere than in the winter, smaller and higher at the equator,
  deeper and larger in the equatorial belts and small at the poles. Solar
  heating on tropospheric haze is proposed as a possible mechanism
  for this effect; the increased efficiency of ortho- to para-hydrogen
  conversion in the southern hemisphere is consistent with the presence
  of larger aerosols in the summer hemisphere, which we demonstrate to be
  qualitatively consistent with previous studies of Saturn's tropospheric
  aerosol distribution.

---------------------------------------------------------
Title: Observations of Jupiter supporting the New Horizons encounter
    and at the onset of a period of "global upheaval"
Authors: Orton, G.; Yanamandra-Fisher, P.; Baines, K.; Mousis, O.;
   Vanzi, L.; Hayward, T.; De Buizer, J.; Simon-Miller, A.; Bjoraker,
   G.; Fletcher, L.; Edkins, E.; Kemerer, J.
2007epsc.conf..611O    Altcode:
  Observations of Jupiter were made between February and June of 2007 to
  provide both increased spectral support and an extended timeline for the
  New Horizons remotesensing of Jupiter's atmosphere. Several ground-based
  facilities were used, using the NASA Infrared Telescope Facility
  (MIRSI and NSFCam2 mid- and near-infrared instruments, respectively),
  Gemini/South (T-Recs mid-infrared camera/spectrometer), and ESO's Very
  Large Telescope (VISIR mid-infrared camera/spectrometer). Midinfrared
  observations from the large telescopes provide the maximum possible
  spatial resolution in the mid-infrared, as the point-response
  function is primarily defined by the limitations of diffraction
  rather than atmospheric turbulence. In mid-February, the north
  and south auroral-generated stratospheric hot spots were resolved
  spatially, possibly for the first time; the southern one being bright
  in methane, ethylene and ethane emission. In contrast, the northern
  one was recognizable in all of these emissions, but barely above the
  background level. Subsequent observations in March and thereafter
  did not detect any enhanced emission from the north. Observations
  of polar regions provided evidence of distinct boundaries to polar
  airmasses which coincided with the locations of high-altitude haze
  layers. These high-resolution images revealed that temperatures in
  the interior of the Great Red Spot were not elliptically symmetric but
  were warmer to the south and center of the vortex. Observations from
  March to June coincided with the initiation of several vertical jets in
  the southern portion of Jupiter's North Temperate Belt (NTBs), which
  precede a major color change in the entire belt and often signal the
  beginning of an epoch of "global upheaval" in Jupiter's cloud system
  with major disruptions to its typical appearance. Our observations
  determine the altitude of these outbursts and their influence on the
  temperature field.

---------------------------------------------------------
Title: Solar active region emergence and flare productivity
Authors: Dalla, Silvia C.; Fletcher, Lyndsay; Walton, Nicholas A.
2007HiA....14..614D    Altcode: 2006IAUSS...3E..45D
  We use the workflow capabilities of the AstroGrid Virtual Observatory
  system (&lt;http://www.astrogrid.org&gt;) to analyse the relation
  between flare productivity and location of Active Region (AR)
  emergence on the Sun. Specifically, we investigate whether emergence
  of a new region near existing ones results in increased productivity
  of the new and/or pre-existing AR. To address this question, we build
  a series of workflows that perform queries to catalogues of regions and
  flares, and operations on the results of the queries. There is a strong
  East-West asymmetry in the location of emergence of new regions. We do
  not find a significant difference between the flaring rate of paired
  and isolated regions, when we choose a value of 12° as the cutoff
  between the two populations.

---------------------------------------------------------
Title: Flare productivity of newly-emerged paired and isolated solar
    active regions
Authors: Dalla, S.; Fletcher, L.; Walton, N. A.
2007A&A...468.1103D    Altcode:
  Aims:We investigate whether sunspot regions that emerge near existing
  ones are more flare productive than those that emerge isolated. <BR
  />Methods: We analyse a sample of 2115 new regions obtained from the
  USAF/Mount Wilson catalogue of sunspot regions. For our analysis
  we use AstroGrid, a Virtual Observatory developed in the UK, to
  build a series of workflows that perform queries to catalogues
  of solar regions and flares, and operations on the results of the
  queries. If a new region emerged through the solar surface within
  12° of a pre-existing one, we classify it as paired, otherwise as
  isolated. <BR />Results: We find that paired regions are more flare
  productive than isolated ones, although this is a small effect. Here
  only soft X-ray flares of magnitude greater than C1.0 are considered,
  and flare productivity is characterised by the percentage of regions
  that produced at least one flare over 4 days since emergence, and by
  the average number of flares over the same period. For paired regions,
  we also consider the flare productivity of the nearby companion region
  and find that if a flare does happen within the pair, it will more
  likely take place in the companion region than in the newly-emerged
  one. Our results show that although emergence in proximity to another
  region can slightly increase the probability of a flare taking place,
  presumably by increasing the likelihood of magnetic reconnection and
  significant change in magnetic topology, this is not a large effect. It
  appears that intrinsic properties of the region are the key factor
  in determining whether or not it will produce flares, as opposed to
  interaction with pre-existing regions.

---------------------------------------------------------
Title: Energy Deposition in White Light Flares with TRACE and RHESSI
Authors: Fletcher, L.; Hannah, I. G.; Hudson, H. S.; Metcalf, T. R.
2007ASPC..368..423F    Altcode:
  In Fletcher et al. (2007) we investigated the white light (WL) continuum
  during solar flares and its relationship to energy deposition by
  electron beams. In 9 flare events, spanning GOES classifications from
  C4.8 to M9.1, we have high cadence TRACE WL and RHESSI hard X-ray
  observations, and compare the WL radiative power output with that
  provided by flare electrons. Under the thick--target model assumptions,
  we find that the electron beam must extend down to 15--20 keV, and the
  energy input to the chromosphere should occur within the collisional
  stopping depth of these electrons - approximately 2× 10<SUP>-4</SUP>
  g cm<SUP>-2</SUP>. In this short paper, we discuss some ideas on flare
  WL emission, summarise the results of the Fletcher et al. (2007)
  study and discuss their implications for chromospheric heating and
  white light flare emission.

---------------------------------------------------------
Title: Electron Acceleration By Inertial Alfven Waves In The Impulsive
    Phase Of A Solar Flare
Authors: Hudson, Hugh S.; Fletcher, L.
2007AAS...210.9303H    Altcode: 2007BAAS...39R.211H
  The impulsive phase of a solar flare marks the epoch of rapid conversion
  of energy stored in the pre-flare coronal magnetic field. Hard X-ray
  observations imply that a substantial fraction of flare energy released
  during the impulsive phase is converted to the kinetic energy of mildly
  relativistic electrons (10-100 keV). The liberation of the magnetic
  free energy occurs as the coronal magnetic field reconfigures and
  relaxes following reconnection. Therefore, we investigate a scenario
  in which the electron acceleration is caused by the agents of this
  reconfiguration -- the large-scale Alfven waves which propagate the
  field changes throughout the atmosphere. In a plasma with β &lt;
  m<SUB>e</SUB>/m<SUB>p</SUB>, these waves propagate as inertial
  Alfven waves which, in the presence of strong spatial gradients,
  generate field-aligned electric fields that can accelerate electrons
  to energies on the order of 10 keV and above. This novel view also
  provides an interpretation of the recently-observed rapid variations of
  the line-of-sight component of the photospheric magnetic field during
  the flare impulsive phase, and offers solutions to some perplexing flare
  problems, such as the flare “number problem” of finding sufficient
  and resupplying sufficient electrons to explain the impulsive-phase
  hard X-ray emission.

---------------------------------------------------------
Title: The meridional phosphine distribution in Saturn's upper
    troposphere from Cassini/CIRS observations
Authors: Fletcher, L. N.; Irwin, P. G. J.; Teanby, N. A.; Orton, G. S.;
   Parrish, P. D.; Calcutt, S. B.; Bowles, N.; de Kok, R.; Howett, C.;
   Taylor, F. W.
2007Icar..188...72F    Altcode:
  The Cassini Composite Infrared Spectrometer (CIRS) has been used
  to derive the vertical and meridional variation of temperature and
  phosphine (PH <SUB>3</SUB>) abundance in Saturn's upper troposphere. PH
  <SUB>3</SUB> has a significant effect on the measured radiances in the
  thermal infrared and between May 2004 and September 2005 CIRS recorded
  thousands of spectra in both the far (10-600 cm <SUP>-1</SUP>) and mid
  (600-1400 cm <SUP>-1</SUP>) infrared, at a variety of latitudes covering
  the southern hemisphere. Low spectral resolution (15 cm <SUP>-1</SUP>)
  data has been used to constrain the temperature structure of the
  troposphere between 100 and 500 mbar. The vertical distributions of
  phosphine and ammonia were retrieved from far-infrared spectra at
  the highest spectral resolution (0.5 cm <SUP>-1</SUP>), and lower
  resolution (2.5 cm <SUP>-1</SUP>) mid-infrared data were used to map
  the meridional variation in the abundance of phosphine in the 250-500
  mbar range. Temperature variations at the 250 mbar level are shown
  to occur on the same scale as the prograde and retrograde jets in
  Saturn's atmosphere [Porco, C.C., and 34 colleagues, 2005. Science
  307, 1243-1247]. The PH <SUB>3</SUB> abundance at 250 mbar is found
  to be enhanced at the equator when compared with mid-latitudes. At
  mid latitudes we see anti-correlation between temperature and PH
  <SUB>3</SUB> abundance at 250 mbar, phosphine being enhanced at 45° S
  and depleted at 25 and 55° S. The vertical distribution is markedly
  different polewards of 60-65° S, with depleted PH <SUB>3</SUB> at
  500 mbar but a slower decline in abundance with altitude when compared
  with the mid-latitudes. This variation is similar to the variations of
  cloud and aerosol parameters observed in the visible and near infrared,
  and may indicate the subsidence of tropospheric air at polar latitudes,
  coupled with a diminished sunlight penetration depth reducing the rate
  of PH <SUB>3</SUB> photolysis in the polar region.

---------------------------------------------------------
Title: Birth and evolution of a dense coronal loop in a complex
    flare region
Authors: Bone, L.; Brown, J. C.; Fletcher, L.; Veronig, A.; White, S.
2007A&A...466..339B    Altcode:
  Context: During the 14th/15th of April 2002, several flares occurred
  in NOAA active region complex 9893/9910. Two of these were previously
  interpreted as having anomalously high coronal column densities. <BR
  />Aims: We develop a scenario using multiwavelength observations
  to explain the high coronal column density (≈10<SUP>20</SUP>
  cm<SUP>-2</SUP>) present at the onset of the 14th April 2002 M3.7
  hard X-ray event. <BR />Methods: Prior to this event a series of
  flares occurred in close temporal and spatial proximity. We observe
  the sequence of flares in a multiwavelength regime from radio to hard
  X-rays. This allows us to study the particle acceleration and plasma
  evaporation in these events. <BR />Results: The observations of these
  flares lead us to propose a sequence of reconnections between multiple
  systems of loops in a 3 dimensional field geometry. We suggest that
  the dense loops in the M3.7 event can be explained as being already
  filled with plasma from the earlier events; these loops then themselves
  become unstable or reconnect leading to particle acceleration into
  an overdense coronal environment. We explore the possibility that a
  high-beta disruption is behind the instability of these dense loops,
  leading to the 14th April 2002 M3.7 event and the observation of hard
  X-rays in the corona at energies up to ≈50 keV.

---------------------------------------------------------
Title: Fast Alfvén Wave Heating and Acceleration of Ions in a
    Nonuniform Magnetoplasma
Authors: McKay, R. J.; McClements, K. G.; Fletcher, L.
2007ApJ...658..631M    Altcode:
  A test-particle approach is used to study the collisionless
  response of protons to cold plasma fast Alfvén waves propagating
  in a nonuniform magnetic field: specifically, a two-dimensional
  X-point field. The field perturbations associated with the waves,
  which are assumed to be azimuthally symmetric and invariant in the
  direction orthogonal to the X-point plane, are exact solutions of the
  linearized ideal magnetohydrodynamic (MHD) equations. The protons are
  initially Maxwellian, at temperatures that are consistent with the
  cold plasma approximation. Two kinds of wave solution are invoked:
  global perturbations, with inward- and outward-propagating components;
  and localized purely inward-propagating waves, the wave electric
  field E having a preferred direction. In both cases the protons are
  effectively heated in the direction parallel to the magnetic field,
  although the parallel velocity distribution is generally non-Maxwellian
  and some protons are accelerated to highly suprathermal energies. This
  heating and acceleration can be attributed to the fact that protons
  undergoing EXB drifts due to the presence of the wave are subject to
  a force in the direction parallel to B. The localized wave solution
  produces more effective proton heating than the global solution,
  and successive wave pulses have a synergistic effect. This process,
  which could play a role in both solar coronal heating and late-phase
  heating in solar flares, is effective for all ion species, but it has
  a negligible direct effect on electrons. However, both electrons and
  heavy ions would be expected to acquire a temperature comparable to
  that of the protons on collisional timescales.

---------------------------------------------------------
Title: Spaceward Bound: Field Training for the Next Generation of
    Space Explorers
Authors: McKay, C. P.; Coe, L. H.; Battler, M.; Bazar, D.; Boston, P.;
   Conrad, L.; Day, B.; Fletcher, L.; Graham, P.; Green, R.; Heldmann,
   J.; Muscatello, T.; Rask, J.; Smith, H.; Sun, H.; Zubrin, R.
2007LPI....38.1467M    Altcode:
  Spaceward Bound is an educational program developed at NASA Ames
  in partnership with The Mars Society, and funded by the Exploration
  Systems Mission Directorate (ESMD) at NASA Headquarters.

---------------------------------------------------------
Title: Oxygen compounds in Titan's stratosphere as observed by
    Cassini CIRS
Authors: de Kok, R.; Irwin, P. G. J.; Teanby, N. A.; Lellouch, E.;
   Bézard, B.; Vinatier, S.; Nixon, C. A.; Fletcher, L.; Howett, C.;
   Calcutt, S. B.; Bowles, N. E.; Flasar, F. M.; Taylor, F. W.
2007Icar..186..354D    Altcode:
  We have investigated the abundances of Titan's stratospheric oxygen
  compounds using 0.5 cm<SUP>-1</SUP> resolution spectra from the
  Composite Infrared Spectrometer on the Cassini orbiter. The CO abundance
  was derived for several observations of far-infrared nadir spectra,
  taken at a range of latitudes (75° S-35° N) and emission angles
  (0°-60°), using rotational lines that have not been analysed before
  the arrival of Cassini at Saturn. The derived volume mixing ratios
  for the different observations are mutually consistent regardless of
  latitude. The weighted mean CO volume mixing ratio is 47±8 ppm if CO
  is assumed to be uniform with latitude. H<SUB>2</SUB>O could not be
  detected and an upper limit of 0.9 ppb was determined. CO<SUB>2</SUB>
  abundances derived from mid-infrared nadir spectra show no significant
  latitudinal variations, with typical values of 16±2 ppb. Mid-infrared
  limb spectra at 55° S were used to constrain the vertical profile of
  CO<SUB>2</SUB> for the first time. A vertical CO<SUB>2</SUB> profile
  that is constant above the condensation level at a volume mixing ratio
  of 15 ppb reproduces the limb spectra very well below 200 km. This
  is consistent with the long chemical lifetime of CO<SUB>2</SUB> in
  Titan's stratosphere. Above 200 km the CO<SUB>2</SUB> volume mixing
  ratio is not well constrained and an increase with altitude cannot be
  ruled out there.

---------------------------------------------------------
Title: A TRACE White Light and RHESSI Hard X-Ray Study of Flare
    Energetics
Authors: Fletcher, L.; Hannah, I. G.; Hudson, H. S.; Metcalf, T. R.
2007ApJ...656.1187F    Altcode:
  In this paper we investigate the formation of the white-light (WL)
  continuum during solar flares and its relationship to energy deposition
  by electron beams inferred from hard X-ray emission. We analyze nine
  flares spanning GOES classifications from C4.8 to M9.1, seven of which
  show clear cospatial RHESSI hard X-ray and TRACE WL footpoints. We
  characterize the TRACE WL/UV continuum energy under two simplifying
  assumptions: (1) a blackbody function, or (2) a Paschen-Balmer
  continuum model. These set limits on the energy in the continuum,
  which we compare with that provided by flare electrons under the
  usual collisional thick-target assumptions. We find that the power
  required by the white-light luminosity enhancement is comparable to
  the electron beam power required to produce the HXR emission only if
  the low-energy cutoff to the spectrum is less than 25 keV. The bulk
  of the energy required to power the white-light flare (WLF) therefore
  resides at these low energies. Since such low-energy electrons cannot
  penetrate deep into a collisional thick target, this implies that the
  continuum enhancement is due to processes occurring at moderate depths
  in the chromosphere.

---------------------------------------------------------
Title: Vertical profiles of HCN, HC <SUB>3</SUB>N, and C <SUB>2</SUB>H
    <SUB>2</SUB> in Titan's atmosphere derived from Cassini/CIRS data
Authors: Teanby, N. A.; Irwin, P. G. J.; de Kok, R.; Vinatier, S.;
   Bézard, B.; Nixon, C. A.; Flasar, F. M.; Calcutt, S. B.; Bowles,
   N. E.; Fletcher, L.; Howett, C.; Taylor, F. W.
2007Icar..186..364T    Altcode:
  Mid-infrared limb spectra in the range 600-1400 cm<SUP>-1</SUP>
  taken with the Composite InfraRed Spectrometer (CIRS) on-board
  the Cassini spacecraft were used to determine vertical profiles of
  HCN, HC<SUB>3</SUB>N, C<SUB>2</SUB>H<SUB>2</SUB>, and temperature
  in Titan's atmosphere. Both high (0.5 cm<SUP>-1</SUP>) and low
  (13.5 cm<SUP>-1</SUP>) spectral resolution data were used. The 0.5
  cm<SUP>-1</SUP> data gave profiles at four latitudes and the 13.5
  cm<SUP>-1</SUP> data gave almost complete latitudinal coverage of
  the atmosphere. Both datasets were found to be consistent with each
  other. High temperatures in the upper stratosphere and mesosphere
  were observed at Titan's northern winter pole and were attributed to
  adiabatic heating in the subsiding branch of a meridional circulation
  cell. On the other hand, the lower stratosphere was much colder in
  the north than at the equator, which can be explained by the lack
  of solar radiation and increased IR emission from volatile enriched
  air. HC<SUB>3</SUB>N had a vertical profile consistent with previous
  ground based observations at southern and equatorial latitudes,
  but was massively enriched near the north pole. This can also be
  explained in terms of subsidence at the winter pole. A boundary
  observed at 60° N between enriched and un-enriched air is consistent
  with a confining polar vortex at 60° N and HC<SUB>3</SUB>N's short
  lifetime. In the far north, layers were observed in the HC<SUB>3</SUB>N
  profile that were reminiscent of haze layers observed by Cassini's
  imaging cameras. HCN was also enriched over the north pole, which
  gives further evidence for subsidence. However, the atmospheric
  cross section obtained from 13.5 cm<SUP>-1</SUP> data indicated
  a HCN enriched layer at 200-250 km, extending into the southern
  hemisphere. This could be interpreted as advection of polar enriched
  air towards the south by a meridional circulation cell. This is
  observed for HCN but not for HC<SUB>3</SUB>N due to HCN's longer
  photochemical lifetime. C<SUB>2</SUB>H<SUB>2</SUB> appears to have a
  uniform abundance with altitude and is not significantly enriched in
  the north. This is consistent with observations from previous CIRS
  analysis that show increased abundances of nitriles and hydrocarbons
  but not C<SUB>2</SUB>H<SUB>2</SUB> towards the north pole.

---------------------------------------------------------
Title: A Magnetometer For The Solar Orbiter Mission
Authors: Carr, C. M.; Horbury, T. S.; Balogh, A.; Baumjohann, W.;
   Bavassano, B.; Breen, A.; Burgess, D.; Cargill, P. J.; Brooker, N.;
   Erdõs, G.; Fletcher, L.; Forsyth, R. J.; Giacalone, J.; Glassmeier,
   K. -H.; Hoeksema, J. T.; Goldstein, M. L.; Lockwood, M.; Magnes, W.;
   Masimovic, M.; Marsch, G.; Matthaeus, W. H.; Murphy, N.; Nakariakov,
   V. M.; Pacheco, J. R.; Pincon, J. -L.; Riley, P.; Russell, C. T.;
   Schwartz, S. J.; Szabo, A.; Thompson, M.; Vainio, R.; Velli, M.;
   Vennerstrom, S.; Walsh, R.; Wimmer-Schweingruber, R.; Zank, G.
2007ESASP.641E..41C    Altcode:
  The magnetometer is a key instrument to the Solar Orbiter mission. The
  magnetic field is a fundamental parameter in any plasma: a precise
  and accurate measurement of the field is essential for understanding
  almost all aspects of plasma dynamics such as shocks and stream-stream
  interactions. Many of Solar Orbiter's mission goals are focussed
  around the links between the Sun and space. A combination of in situ
  measurements by the magnetometer, remote measurements of solar magnetic
  fields and global modelling is required to determine this link and
  hence how the Sun affects interplanetary space. The magnetic field
  is typically one of the most precisely measured plasma parameters and
  is therefore the most commonly used measurement for studies of waves,
  turbulence and other small scale phenomena. It is also related to the
  coronal magnetic field which cannot be measured directly. Accurate
  knowledge of the magnetic field is essential for the calculation of
  fundamental plasma parameters such as the plasma beta, Alfvén speed
  and gyroperiod. We describe here the objectives and context of magnetic
  field measurements on Solar Orbiter and an instrument that fulfils those
  objectives as defined by the scientific requirements for the mission.

---------------------------------------------------------
Title: New upper limits for hydrogen halides on Saturn derived from
    Cassini-CIRS data
Authors: Teanby, N. A.; Fletcher, L. N.; Irwin, P. G. J.; Fouchet,
   T.; Orton, G. S.
2006Icar..185..466T    Altcode:
  Far infrared spectra (10-600 cm <SUP>-1</SUP>) from Cassini's
  Composite InfraRed Spectrometer (CIRS) were used to determine
  improved upper limits of hydrogen halides HF, HCl, HBr, and HI in
  Saturn's atmosphere. Three observations, comprising a total of 3088
  spectra, gave 3 σ upper limits on HF, HCl, HBr, and HI volume mole
  fractions of 8.0×10, 6.7×10, 1.3×10, and 1.4×10, respectively,
  at the 500 mbar pressure level. These upper limits confirm sub-solar
  abundances of halide species for HF, HCl, and HBr in Saturn's upper
  atmosphere—consistent with predictions from thermochemical models and
  influx of material from meteoroids. Our upper limit for HCl is 16 times
  lower than the tentative detection at 1.1×10 reported by Weisstein and
  Serabyn [Weisstein, E.W., Serabyn, E., 1996. Icarus 123, 23-36]. These
  observations are not sensitive to the deep halide abundance, which is
  expected to be enriched relative to the solar composition.

---------------------------------------------------------
Title: Comparison of Earth-Based Longitudinal Studies and Cassini
CIRS Observations of Saturn's Temperature Field: Modifications of
    Seasonal Forcing Models and the Discovery of Nonseasonal Low-Latitude
    Thermal Oscillations
Authors: Orton, G.; Parrish, P.; Yanamandra-Fisher, P.; Fisher,
   B.; Fletcher, L.; Irwin, P.; Nelson, J.; Gezari, D.; Fuse, T.;
   Fujiyoshi, T.
2006AGUFM.P41C1306O    Altcode:
  During the sequence of observations made by Cassini CIRS from 2004 to
  the present, supporting observations of Saturn have been made in the
  same spectral region. Most of these were taken at NASA's 3-m Infrared
  Telescope Facility (IRTF), but they were supplemented by observations
  from the 8.2-m Subaru Telescope. An examination of temperature field
  retrieved from form spacecraft and earth-based observations has required
  us to assess carefully the limitation of vertical sensitivity for the
  ground-based images and the calibration of both geometry and absolute
  radiance. Keeping those limitations in mind, the combination of the
  two data sets has provided evidence that is consistent with the absence
  of effective cloud opacity in the mid- and far-infrared. Furthermore,
  the full sequence of ground-based imaging stretches back as early as
  1990. These observations clearly indicate the expected hemispherically
  antisymmetric seasonal forcing, but with relaxation times considerably
  shorter than the 9-year scales in both the stratosphere and upper
  troposphere expected from gaseous constituents alone. An important non-
  seasonal effect was also noted in the long-term behavior of the equator
  and low-latitude regions which undergo a periodic oscillation with an
  alternating phases of thermal waves at the equator and at latitudes
  5-25 degrees poleward in both hemispheres over a period of 20 years
  or longer. The observed behavior is consistent with the different
  stratospheric temperature profiles of these regions. This phenomenon
  is best explained by the presence of upwelling thermal waves which are
  similar to the Earth's quasi-biennial oscillation (QBO) and Jupiter's
  quasi-quadrennial oscillation (QQO).

---------------------------------------------------------
Title: Solar And Cosmic Ray Physics And The Space Environment:
    Studies For And With LISA
Authors: Shaul, D. N. A.; Aplin, K. L.; Araújo, H.; Bingham, R.;
   Blake, J. B.; Branduardi-Raymont, G.; Buchman, S.; Fazakerley, A.;
   Finn, L. S.; Fletcher, L.; Glover, A.; Grimani, C.; Hapgood, M.;
   Kellet, B.; Matthews, S.; Mulligan, T.; Ni, W. -T.; Nieminen, P.;
   Posner, A.; Quenby, J. J.; Roming, P.; Spence, H.; Sumner, T.; Vocca,
   H.; Wass, P.; Young, P.
2006AIPC..873..172S    Altcode:
  With data analysis preparations for LISA underway, there has been
  renewed interest in studying solar, cosmic ray and environmental
  physics for, and using LISA. The motivation for these studies is two
  fold. The primary incentive is to predict and consequently minimize
  the impact of disturbances associated with these factors, to maximize
  LISA's gravitational wave scientific yield. The second stimulus is
  the unique opportunity that is afforded by LISA's long-baseline
  3-spacecraft configuration for studies of solar, cosmic ray and
  environmental physics. Here we present an overview of recent progress
  in these studies.

---------------------------------------------------------
Title: Optimal filtering of solar images using soft morphological
    processing techniques
Authors: Marshall, S.; Fletcher, L.; Hough, K.
2006A&A...457..729M    Altcode:
  Context: .CCD images obtained by space-based astronomy and solar
  physics are frequently spoiled by galactic and solar cosmic rays, and
  particles in the Earth's radiation belt, which produces an overlaid,
  often saturated, speckle.<BR /> Aims: .We describe the development
  and application of a new image-processing technique for the removal of
  this noise source, and apply it to SOHO/LASCO coronagraph images.<BR />
  Methods: .We employ soft morphological filters, a branch of non-linear
  image processing originating from the field of mathematical morphology,
  which are particularly effective for noise removal.<BR /> Results:
  .The soft morphological filters result in a significant improvement in
  image quality, and perform significantly better than other currently
  existing methods based on frame comparison, thresholding, or simple
  morphologies.<BR /> Conclusions: .This is a promising and adaptable
  technique that should be extendable to other space-based solar and
  astronomy datasets.

---------------------------------------------------------
Title: Titan's Stratospheric Aerosols and Condensate Clouds as
    Observed with Cassini CIRS
Authors: de Kok, Remco; Irwin, P. G.; Teanby, N. A.; Samuelson, R. E.;
   Nixon, C. A.; Jennings, D. E.; Fletcher, L.; Howett, C.; Calcutt,
   S. B.; Bowles, N. E.; Flasar, F. M.; Taylor, F. W.; Cassini/CIRS Team
2006DPS....38.2203D    Altcode: 2006BAAS...38R.519D
  Four broad spectral features were identified in far-infrared limb
  spectra from the Cassini Composite Infrared Spectrometer (CIRS). The
  features are broader than the spectral resolution, which suggests that
  they are caused by particulates in Titan's stratosphere. We derive here
  the spectral properties and variations with altitude and latitude for
  these four features. Titan's main aerosol is called Haze 0 here. It
  is present at all wavenumbers in the far-infrared and is found to
  have a fractional scale height between 1.6-1.7 with a small increase
  in opacity in the north. A second feature around 140 cm<SUP>-1</SUP>
  (Haze A) has similar spatial properties to Haze 0, but has a smaller
  fractional scale height of 1.2-1.3. Both Haze 0 and Haze A show an
  increase in abundance below 100 km, perhaps indicative of a scattering
  cloud. Two other features (Haze B around 220 cm<SUP>-1</SUP> and Haze
  C around 190 cm<SUP>-1</SUP>) have a large maximum in their density
  profiles at 140 km and 90 km respectively. Haze B is much more abundant
  in the northern hemisphere compared to the southern hemisphere. Haze
  C also shows a large increase towards the north, but then disappears
  at 85<SUP>o</SUP>N. This work is supported by the Prins Bernhard
  Cultuurfond and Pieter Beijer Fonds.

---------------------------------------------------------
Title: Variations In The Abundance Of Acetylene And Ethane In The
    Atmosphere Of Saturn, As Deduced From Cassini/CIRS And IRTF/MIRI
    Measurements.
Authors: Howett, Carly; Irwin, P.; Yanamandra-Fisher, P.; Parrish,
   P.; Orton, G.; Fletcher, L.; Teanby, N.; CIRS Team
2006DPS....38.3907H    Altcode: 2006BAAS...38..555H
  High resolution data taken by Cassini/CIRS from June to November
  2004 are analysed to deduce variations in the abundance of acetylene
  and ethane. The data has good spatial coverage of Saturn's southern
  latitudes covering 5 to 80 S, binned by latitude into strips of 2
  degrees. Tropospheric and stratospheric temperatures are initially
  deduced using the hydrogen S(1) continuum and the methane v<SUB>4</SUB>
  band. Using the retrieved temperature profiles latitudinal variations
  in the abundance of acetylene and ethane are determined using the
  v<SUB>5</SUB> band of acetylene and the v<SUB>9</SUB> band of ethane. <P
  />These results are compared with ground-based observations of Saturn
  taken with MIRSI on the IRTF in January and February 2006. Temperature
  profiles are derived from fitting the hydrogen S(1) continuum and
  the methane v<SUB>4</SUB> band. Variations in the abundance of the two
  hydrocarbons are then determined using the R branch of the v<SUB>5</SUB>
  band of acetylene and the v<SUB>9</SUB> band of ethane. <P />This
  research was funded by the UK Particle Physics and Astronomy Research
  Council and the NASA Cassini Project.

---------------------------------------------------------
Title: The Vortex Formerly Known as White Oval BA: Temperature
    Structure, CloudProperties and Dynamical Simulation
Authors: Orton, Glenn S.; Yanamandra-Fisher, P. A.; Parrish, P. D.;
   Mousis, O.; Pantin, E.; Fuse, T.; Fujiyoshi, T.; Simon-Miller, A.;
   Morales-Juberias, R.; Tollestrup, E.; Connelley, M.; Trujillo, C.;
   Hora, J.; Irwin, P.; Fletcher, L.; Hill, D.; Kollmansberger, S.
2006DPS....38.3902O    Altcode: 2006BAAS...38..554O
  White Oval BA, constituted from 3 predecessor vortices (known as
  Jupiter's "classical" White Ovals) after successive mergers in 1998
  and 2000, became second-largest vortex in the atmosphere of Jupiter
  (and possibly the solar system) at the time of its formation. While
  it continues in this distinction,it required a name change after
  a 2005 December through 2006 February transformation which made it
  appear visually the same color as the Great Red Spot. Our campaign
  to understand the changes involved examination of the detailed
  color and wind field using Hubble Space Telescope instrumentation
  on several orbits in April. The field of temperatures, ammonia
  distribution and clouds were also examined using the mid-infrared
  VISIR camera/spectrometer on ESO's 8.2-m Very Large Telescope, the
  NASA Infrared telescope with the mid-infrared MIRSI instrument and
  the refurbished near-infrared facility camera NSFCam2. High-resolution
  images of the Oval were made before the color change with the COMICS
  mid-infrared facility on the 8.2-m Subaru telescope.We are using
  these images, togther with images acquired at the IRTF and with
  the Gemini/North NIRI near-infrared camera between January, 2005,
  and August, 2006, to characterize the extent to which changes in
  storm strength (vorticity, postive vertical motion) influenced (i)
  the depth from which colored cloud particles may have been "dredged
  up" from depth or (ii) the altitude to which particles may have been
  lofted and subject to high-energy UV radiation which caused a color
  change, as alternative explanations for the phenomenon. Clues to this
  will provide clues to the chemistry of Jupiter's cloud system and its
  well-known colors in general. The behavior of Oval BA, its interaction
  with the Great Red Spot in particular,are also being compared with
  dynamical models run with the EPIC code.

---------------------------------------------------------
Title: Vertical Profiles Of Nitrile Compounds In Titan's Atmosphere
    Measured By Cassini CIRS As A Tracer Of Atmospheric Circulation
Authors: Teanby, Nicholas A.; Irwin, P. G.; de Kok, R.; Vinatier, S.;
   Bezard, B.; Nixon, C. A.; Flasar, M.; Calcutt, S. B.; Bowles, N. E.;
   Fletcher, L.; Howett, C.; Taylor, F. W.
2006DPS....38.3204T    Altcode: 2006BAAS...38..543T
  The vertical profiles of nitrile compounds including HCN and HC3N
  were derived from mid-infrared observations taken with the Composite
  InfraRed Spectrometer (CIRS) on board the Cassini orbiter. <P />Nitrile
  compounds are created by photochemical reactions and have lifetimes
  ranging from under a year to tens of years - of the same order as
  a Titan year. Therefore, abundance variations can be used to probe
  atmospheric motion. <P />We used the limb sounding capabilities of CIRS
  to retrieve vertical profiles of HCN and HC3N from 85S to 85N. First,
  the segment of the mid-IR spectrum from 1240-1360cm-1 was used to
  retrieve temperature. Second, sub-spectra were extracted from the
  600-750cm-1 region and used to obtain vertical profiles of nitriles. The
  limiting vertical resolution of these profiles is determined by the
  field-of-view size at the tangent height, which varied between 10 and
  50km. <P />Both high (0.5cm-1) and low (13.5cm-1) spectral resolution
  data were used to derive the abundance profiles. The high resolution
  data was more precise, but only covered a few discrete latitudes,
  whereas the low resolution data covered almost the entire limb from
  north- to south-pole, but required verification by comparison with
  the high resolution data. <P />HC3N was massively enriched near the
  north pole, which can be explained in terms of subsidence. A boundary
  observed at 60N between enriched and un-enriched air is consistent with
  a confining polar vortex at 60N and HC3N's short lifetime. <P />HCN
  was also enriched over the north pole, which gives further evidence
  for subsidence. However, the atmospheric cross section obtained from
  13.5cm-1 data indicated a HCN enriched layer at 200-250km, extending
  into the southern hemisphere. This could be interpreted as advection
  of polar enriched air towards the south by a meridional circulation
  cell. This is observed for HCN but not for HC3N due to HCN's longer
  photochemical lifetime.

---------------------------------------------------------
Title: Modelling Temperature Distribution Along A Magnetic Field Line
Authors: Pollock, J. A.; Fletcher, L.
2006IAUJD...3E...4P    Altcode:
  Fast electrons moving along a magnetic field line in the solar
  atmosphere undergo collisions with the particles of the background
  plasma. In doing so, they deposit some of their energy into the
  background plasma, increasing its temperature. In addition to this
  temperature increase, the plasma also undergoes radiative and conductive
  cooling, which alters the temperature distribution along the field
  line. Using stochastic simulations, we can model the movement of fast
  electrons along a field line and calculate changes in their energy
  as they undergo collisions. We use this data to map the temperature
  distribution along the field line, including radiative and conductive
  cooling, for injected electron beams of various initial distributions
  and injection parameters. Temperature maps, and the radiation maps
  that arise from them, can be compared with observations from RHESSI
  and other satellites.

---------------------------------------------------------
Title: Observations of simultaneous coronal loop shrinkage and
    expansion during the decay phase of a solar flare
Authors: Khan, J. I.; Fletcher, L.; Nitta, N. V.
2006A&A...453..335K    Altcode:
  We report what we believe are the first direct and unambiguous
  observations of simultaneous coronal magnetic flux loop shrinkage
  and expansion during the decay phase of a solar flare. The retracting
  and expanding loops were observed nearly face-on (i.e., with the loop
  major axis approximately orthogonal to the line of sight) in emission
  in imaging data from the Yohkoh Soft X-ray Telescope (SXT). The
  retracting loop is observed to shrink with a speed of 118 ± 66 km
  s<SUP>-1</SUP>. The faint outward moving loop-like feature occurred
  ~200´´ above the shrinking loop during the time of the shrinking
  loop. We estimate the speed of the outward moving loop was ~129 ± 74
  km s<SUP>-1</SUP>. We interpret the shrinking loop and simultaneous
  outward moving loop as direct evidence for reconnected magnetic field
  lines during a flare.

---------------------------------------------------------
Title: Comparison of the Energy Spectra and Number Fluxes From a
    simple Flare Model to Observations
Authors: Hannah, Iain G.; Fletcher, Lyndsay
2006SoPh..236...59H    Altcode:
  In this paper, we investigate the energy spectra produced by a
  simple test particle X-point model of a solar flare for different
  configurations of the initial electromagnetic field. We find that
  once the reconnection electric field is larger than 1 Vm<SUP>-1</SUP>
  the particle distribution transits from a heated one to a partially
  accelerated one. As we close the separatrices of the X-point and
  the angle in the inflow direction widens we find that more particles
  are accelerated out of the thermal distribution and this power-law
  component extends to lower energies. When we introduce a guiding
  magnetic field component we find that more particles are energised,
  but only up to a maximum energy dictated primarily by the reconnection
  electric field. Despite being able to accelerate particles to
  observable energies and demonstrate behaviour in the energy spectra
  that is consistent with observations, this single X-line model can
  only deliver the number fluxes required for microflares.

---------------------------------------------------------
Title: Modelling Temperature Distribution Along A Field Line
Authors: Pollock, Jennifer A.; Fletcher, L.
2006SPD....37.0108P    Altcode: 2006BAAS...38R.216P
  Fast electrons moving along a magnetic field line in the solaratmosphere
  undergo collisions with the particles of the backgroundplasma. In
  doing so, they deposit some of their energy into thebackground plasma,
  increasing its temperature. In addition to thistemperature increase,
  the plasma also undergoes radiative and conductivecooling, which alters
  the temperature distribution along the field line.Using stochastic
  simulations, we can model the movement of fastelectrons along a field
  line and calculate changes in their energy asthey undergo collisions. We
  use this data to map the temperaturedistribution along the field line,
  including radiative and condutivecooling, for injected electron beams
  of various initial distributionsand injection parameters. Temperature
  maps, and the radiation maps that arise from them, can be compared
  with observations from RHESSI and other satellites.

---------------------------------------------------------
Title: Latitudinal variations of HCN, HC <SUB>3</SUB>N, and C
    <SUB>2</SUB>N <SUB>2</SUB> in Titan's stratosphere derived from
    Cassini CIRS data
Authors: Teanby, N. A.; Irwin, P. G. J.; de Kok, R.; Nixon, C. A.;
   Coustenis, A.; Bézard, B.; Calcutt, S. B.; Bowles, N. E.; Flasar,
   F. M.; Fletcher, L.; Howett, C.; Taylor, F. W.
2006Icar..181..243T    Altcode:
  Mid- and far-infrared spectra from the Composite InfraRed Spectrometer
  (CIRS) have been used to determine volume mixing ratios of nitriles
  in Titan's atmosphere. HCN, HC <SUB>3</SUB>N, C <SUB>2</SUB>H
  <SUB>2</SUB>, and temperature were derived from 2.5 cm <SUP>-1</SUP>
  spectral resolution mid-IR mapping sequences taken during three flybys,
  which provide almost complete global coverage of Titan for latitudes
  south of 60° N. Three 0.5 cm <SUP>-1</SUP> spectral resolution far-IR
  observations were used to retrieve C <SUB>2</SUB>N <SUB>2</SUB> and act
  as a check on the mid-IR results for HCN. Contribution functions peak
  at around 0.5-5 mbar for temperature and 0.1-10 mbar for the chemical
  species, well into the stratosphere. The retrieved mixing ratios of
  HCN, HC <SUB>3</SUB>N, and C <SUB>2</SUB>N <SUB>2</SUB> show a marked
  increase in abundance towards the north, whereas C <SUB>2</SUB>H
  <SUB>2</SUB> remains relatively constant. Variations with longitude
  were much smaller and are consistent with high zonal wind speeds. For
  90°-20° S the retrieved HCN abundance is fairly constant with a
  volume mixing ratio of around 1 × 10 <SUP>-7</SUP> at 3 mbar. More
  northerly latitudes indicate a steady increase, reaching around 4 × 10
  <SUP>-7</SUP> at 60° N, where the data coverage stops. This variation
  is consistent with previous measurements and suggests subsidence over
  the northern (winter) pole at approximately 2 × 10 <SUP>-4</SUP>
  m s <SUP>-1</SUP>. HC <SUB>3</SUB>N displays a very sharp increase
  towards the north pole, where it has a mixing ratio of around 4 ×
  10 <SUP>-8</SUP> at 60° N at the 0.1-mbar level. The difference in
  gradient for the HCN and HC <SUB>3</SUB>N latitude variations can be
  explained by HC <SUB>3</SUB>N's much shorter photochemical lifetime,
  which prevents it from mixing with air at lower latitude. It is also
  consistent with a polar vortex which inhibits mixing of volatile rich
  air inside the vortex with that at lower latitudes. Only one observation
  was far enough north to detect significant amounts of C <SUB>2</SUB>N
  <SUB>2</SUB>, giving a value of around 9 × 10 <SUP>-10</SUP> at 50°
  N at the 3-mbar level.

---------------------------------------------------------
Title: Organization and variation of Saturn's temperature field from
    Cassini CIRS and supporting ground-based observations
Authors: Orton, G.; Parrish, P.; Yanamandra-Fisher, P.; Fisher, B.;
   Fletcher, L.; Irwin, P.; Flasar, M.; Achterberg, R.; Conrath, B.;
   Simon-Miller, A.
2006cosp...36.2583O    Altcode: 2006cosp.meet.2583O
  An extended set of observations of Saturn s thermal field has been
  made by Cassini s Composite Infrared Spectrometer CIRS complemented
  by ground-based stations NASA s Infrared Telescope Facility Gemini
  North Telescope W M Keck Observatory and the Subaru Japanese National
  Telescope Observations by the large telescopes have provided high
  diffraction-limited spatial resolution of Saturn s disk on the order
  of 5000 km although so far these all have been at single points in
  time Thermal images from the NASA IRTF are characterized by spatial
  resolutions of approximately 13 000 km but have been made at more
  frequent intervals in time usually once every month except during
  solar conjunction Cassini CIRS observations of Saturn s temperature
  field have been made primarily in a mode in which a single hemisphere
  is mapped by scanning the central meridian while Saturn rotates
  CIRS spatial resolutions are typically 10 000 km in these maps but
  observations with spatial resolutions as high as 3 000 km have been
  made These observations including support imaging stretching several
  years before the Cassini arrival at Saturn show a warming of the south
  polar region as a result of increased seasonal sunlight a very hot
  south polar spot and a possible warm polar vortex in the south polar
  region Zonal thermal waves also exist at 16 28 38 and 52 degrees S
  planetocentric but they are not always present CIRS measurements of
  the shadowed north polar region do not show a cold counterpart to the
  warm south pole but a more detailed structure Saturn s

---------------------------------------------------------
Title: Latitudinal variations in the temperature and composition of
    Saturn's upper troposphere from Cassini/CIRS
Authors: Fletcher, L. N.; Irwin, P. G. J.; Teanby, N. A.; Orton, G. S.;
   Parrish, P. D.; Calcutt, S. B.; Bowles, N.; de Kok, R.; Howett, C.;
   Cassini/Cirs Team
2006cosp...36..853F    Altcode: 2006cosp.meet..853F
  The Cassini Composite Infrared Spectrometer CIRS Flasar et al 2004 has
  been used to derive the meridional variation of temperature phosphine
  PH 3 and ammonia NH 3 abundance in Saturn s upper troposphere 0 8
  to 0 1 atm Since orbital insertion in July 2004 CIRS has recorded
  thousands of spectra in both the far 10 - 600 cm -1 and mid 600 -
  1400 cm -1 infrared at a variety of apodized spectral resolutions 0 5 -
  15 0 cm -1 and viewing geometries covering both hemispheres of the gas
  giant We use a non-linear optimal estimation retrieval code Irwin et al
  2004 to derive vertical profiles of temperature composition and aerosol
  abundance The abundances of NH 3 and PH 3 are retrieved from rotational
  lines in the 10 - 200 cm -1 region and the nu 4 fundamental of PH 3 at
  1070 - 1200 cm -1 Latitudinal temperature variations at the 0 25 atm are
  shown to occur on the same scale as the prograde and retrograde jets
  in Saturn s atmosphere Porco et al 2005 The distribution of phosphine
  a disequilibrium species in Saturn s cold upper troposphere Orton et al
  2000 2001 may be used as a tracer for the upwelling of constituent-rich
  air from deeper within the atmosphere Elevated abundances of PH 3 at
  polar and equatorial latitudes correlations of PH 3 and NH 3 with the
  belt-zone temperature structure deviations of parahydrogen fraction
  from local thermochemical equilibrium at the equator and evidence for
  atmospheric heating by aerosols at 0 25 atm will also be

---------------------------------------------------------
Title: Organic Matter Analysis of the Hyper-Arid Peruvian Desert in
    comparison to other Hyper-Arid Environments
Authors: Valdivia-Silva, J. E.; Fletcher, L. E.; Navarro-González,
   R.; McKay, C. P.; Pérez Montano, S.; Condori Apaza, R.; Conley, C. A.
2005AGUFM.P51D0949V    Altcode:
  The Peruvian Desert is located along the Pacific coast of southern
  Peru and is a continuation of the Atacama Desert in Chile. The Peruvian
  Desert at the Pampas of La Joya has extreme environmental conditions,
  such as hyperaridity, and a complete absence of macroscopic life. La
  Joya contains volcanic soils with the presence of magnetite and
  quartz. Furthermore, the El Niño phenomena, centralized directly off
  the coast-line near La Joya, provides stronger climactic effects on
  this desert, resulting in higher levels of precipitation which should
  allow for the development of microscopic life. Taking into account
  that life is based on carbon, here we search for relationships between
  soil organic matter detected by oxidation versus pyrolisis (pyr-GC-MS)
  techniques. Our preliminary results showed similar levels of organic
  compounds to Yungay, the hyper-arid core of the Atacama Desert,
  similar levels of organic compounds to the Antarctic Dry Valleys,
  and direct correlation between oxidation and pyrolitic techniques.

---------------------------------------------------------
Title: a Solar Science Case with Astrogrid: Flare Productivity of
    Recently-Emerged Paired and Isolated Active Regions
Authors: Dalla, S.; Fletcher, L.; Walton, N. A.
2005ESASP.600E.117D    Altcode: 2005dysu.confE.117D; 2005ESPM...11..117D
  No abstract at ADS

---------------------------------------------------------
Title: Multiwavelength Observations of a Partially Occulted Solar
    Flare
Authors: Bone, L.; Brown, J. C.; Fletcher, L.
2005ESASP.600E..38B    Altcode: 2005ESPM...11...38B; 2005dysu.confE..38B
  No abstract at ADS

---------------------------------------------------------
Title: Coronal Heating and X-Ray Emission from a Beam of Fast
    Electrons
Authors: Pollock, J. A.; Fletcher, L.
2005ESASP.600E.138P    Altcode: 2005dysu.confE.138P; 2005ESPM...11..138P
  No abstract at ADS

---------------------------------------------------------
Title: X-Ray Quasi-Periodic Pulsations in Solar Flares as
    Magnetohydrodynamic Oscillations
Authors: Foullon, C.; Verwichte, E.; Nakariakov, V. M.; Fletcher, L.
2005ESASP.600E..33F    Altcode: 2005ESPM...11...33F; 2005dysu.confE..33F
  No abstract at ADS

---------------------------------------------------------
Title: Temperature Structure of Saturn from Spectral Mapping by
    Cassini CIRS and Joint High-Resolution Subaru COMICS and IRTF MIRSI
    Mid-Infrared Imaging
Authors: Orton, G.; Parrish, P.; Yanamandra-Fisher, P.; Fletcher, L.;
   Irwin, P.; Fuse, T.; Fujiyoshi, T.; Hagopian, H.; Laakso, T.; Vogt,
   M.; Lotoszinski, J.; Hora, J.
2005AGUFM.P11C0129O    Altcode:
  We report on a joint project of Cassini and ground-based support
  observations of Saturn's temperature field. Several sequences
  of CIRS spectra were made during 2004-2005 which scanned Saturn's
  central meridian using its FP1 (long wavelength-) and its FP3 and FP4
  (intermediate- and short-wavelength) focal planes for the purpose of
  determining temperatures between 1 microbar and 400 mbar total pressure
  at spatial resolutions ranging from 170 to 3800 km (from 0.5 to 11
  great-circle degrees). These infrequent observations (2004 Oct 30;
  2005 March 10, April 8-9, May 22) were supplemented by a program at
  the NASA Infrared Telescope Facility of thermal imaging using the MIRSI
  mid-infrared camera spectrometer with diffraction-limited resolutions of
  ~3000 km, which provided a time sequence which is particularly valuable
  for characterizing wave structure and other time-dependent phenomena and
  for verifying CIRS temperature maps at 10 mbar or between 100 and 400
  mbar pressure. We also obtained diffraction-limited resolutions of 1000
  km thermal images of Saturn from the Subaru Japanese National Telescope
  using their COMICS facility mid-infrared camera/spectrometer on 2005
  April 30 and May 24, providing spatial resolution commensurate with
  the Cassini/CIRS, global imaging, the opportunity for center-to-limb
  studies, and the means to track variability in PH3 and cloud optical
  thickness in very faint spectral regions. The meridional variability of
  temperatures is consistent with the seasonal dependence of temperatures
  documented by two decades of thermal monitoring of Saturn at the IRTF.

---------------------------------------------------------
Title: TRACE white light and RHESSI hard X-rays
Authors: Fletcher, L.; Allred, J.; Hannah, I.; Hudson, H.; Metcalf, T.
2005AGUFMSH13A0286F    Altcode:
  We study the energetics of RHESSI and TRACE observations for a
  sample of 11 solar flares well observed in the TRACE “white light"
  channel. In general, the data show excellent correlations between hard
  X-rays and white light. We discuss the energetics of this relationship
  based upon simple models for the visible/UV continuum, namely (i)
  a non-thermal approximation (Balmer and Paschen continuum), (ii)
  a thermal approximation (blackbody), and (iii) model spectra derived
  from radiation-hydrodynamic modeling. We relate the white-light energy
  and the low-energy cutoff energy of the primary electron spectrum
  required for energetic equivalence. This comparison will be made in
  the context of the flare WL morphology and in comparison with RHESSI
  hard X-ray images.

---------------------------------------------------------
Title: X-Ray Quasi-Periodic Pulsations in Solar Flares as
    Magnetohydrodynamic Oscillations
Authors: Foullon, C.; Verwichte, E.; Nakariakov, V. M.; Fletcher, L.
2005ESASP.596E..46F    Altcode: 2005ccmf.confE..46F
  No abstract at ADS

---------------------------------------------------------
Title: The Observational Motivation for Computational Advances in
    Solar Flare Physics
Authors: Fletcher, Lyndsay
2005SSRv..121..141F    Altcode:
  A solar flare is a violent and transient release of energy in the
  corona of the Sun, associated with the reconfiguration of the coronal
  magnetic field. The major mystery of solar flare physics is the precise
  nature of the conversion of stored magnetic energy into the copious
  accelerated particles that are observed indirectly by the radiation
  that they produce, and also directly with in situ detectors. This
  presents a major challenge for theory and modeling. Recent years have
  brought significant observational advances in the study of solar
  flares, addressing the storage and release of magnetic energy, and
  the acceleration and propagation of fast electrons and ions. This
  paper concentrates on two topics relevant to the early phase of a
  flare, magnetic reconnection and charged particle acceleration and
  transport. Some recent pertinent observations are reviewed and pointers
  given for the directions that, this reviewer suggests, computational
  models should now seek to take.

---------------------------------------------------------
Title: X-ray quasi-periodic pulsations in solar flares as
    magnetohydrodynamic oscillations
Authors: Foullon, C.; Verwichte, E.; Nakariakov, V. M.; Fletcher, L.
2005A&A...440L..59F    Altcode:
  We report the first observation at high spatial resolution of
  long-period quasi-periodic pulsations (QPP) of X-ray radiation during
  solar flares, made possible with the Reuven Ramaty High Energy Solar
  Spectroscopic Imager (RHESSI), supported by complementary data at other
  wavelengths from space-based and ground-based telescopes. Evidence
  for the presence of a transequatorial loop possibly responsible for
  the detected periodicity connected with its kink mode is found. Our
  findings suggest that QPP can be interpreted as a periodic pumping
  of electrons in a compact flaring loop, modulated by oscillations
  in a magnetically linked and larger loop acting as a long-period
  magnetohydrodynamic resonator.

---------------------------------------------------------
Title: Flows in the solar atmosphere due to the eruptions on the
    15th July, 2002
Authors: Harra, L. K.; Démoulin, P.; Mandrini, C. H.; Matthews,
   S. A.; van Driel-Gesztelyi, L.; Culhane, J. L.; Fletcher, L.
2005A&A...438.1099H    Altcode:
  Which kind of flows are present during flares? Are they compatible
  with the present understanding of energy release and which model
  best describes the observations? We analyze successive flare events
  in order to answer these questions. The flares were observed in the
  magnetically complex NOAA active region (AR) 10030 on 15 July 2002. One
  of them is of GOES X-class. The description of these flares and how
  they relate to the break-out model is presented in Gary &amp; Moore
  (2004). The Coronal Diagnostic Spectrometer on board SOHO observed
  this active region for around 14 h. The observed emission lines
  provided data from the transition region to the corona with a field
  of view covering more than half of the active region. In this paper
  we analyse the spatially resolved flows seen in the atmosphere from
  the preflare to the flare stages. We find evidence for evaporation
  occurring before the impulsive phase. During the main phase, the
  ongoing magnetic reconnection is demonstrated by upflows located at
  the edges of the flare loops (while downflows are found in the flare
  loops themselves). We also report the impact of a filament eruption
  on the atmosphere, with flows up to 300 km s<SUP>-1</SUP> observed at
  transition-region temperatures in regions well away from the location
  of the pre-eruptive filament. Our results are consistent with the
  predictions of the break out model before the impulsive phase of the
  flare; while, as the flare progresses, the directions of the flows are
  consistent with flare models invoking evaporation followed by cooling
  and downward plasma motions in the flare loops.

---------------------------------------------------------
Title: Saturn's atmospheric structure: the intercomparison of
    Cassini/CIRS-derived temperatures with ground-based determinations
Authors: Parrish, P. D.; Orton, G. S.; Yanamandra-Fisher, P. A.;
   Fletcher, L.; Irwin, P. G. J.; Teanby, N.; Flasar, F. M.; Nixon,
   C. A.; Simon-Miller, A. A.; Cassini CIRS Team
2005DPS....37.3019P    Altcode: 2005BAAS...37R.680P
  Although Saturn is similar to that of Jupiter in several respects,
  it has yet to be qualitatively-determined whether Saturn experiences
  similar seasonal variation of its equatorial stratosphere as have
  been observed on Jupiter [Orton et al., 1991; Flasar et al., 2003]
  and Earth [Linzen, 1968; reviewed by Baldwin et al., 2003]. While the
  nature of the radiatively-based, seasonal forcing on Jupiter is not
  fully understood, the modulated-temperatures are thought to play an
  important role in the transport of momentum between the troposphere and
  the stratosphere of any planet [Friedson, 1999]. The recent arrival of
  the Cassini-Huygens spacecraft to the Saturnian system provides an ideal
  opportunity to study this phenomena on Saturn. Specifically, what is
  the spatial orientation and temporal organisation of the atmospheric
  structure at upper-tropospheric/lower-stratospheric altitudes with
  regard to the dynamical models of other, better-characterised
  planets? The preliminary analysis, comparing Cassini Composite
  Infrared Spectrometer-derived temperatures with those obtained
  via images taken with NASA's Infrared Telescope Facility will
  be presented. <P />Baldwin, M.P. et al. (2001). Rev. Geophys.,
  29: 179-229. <P />Flasar, F.M. et al. (2003). Nature, 429(6969):
  132-135. <P />Friedson, A.J (1999). Icarus, 137(1):34-55. <P />Lindzen,
  R.S. et al. (1968). J. Atmos. Sci., 25: 1095-1107. <P />Orton,
  G.S. et al. (1991). Science, 252: 537-542. <P />Acknowledgements:
  The acquisition of data described here was accomplished through the
  coordinated effort of Cassini-Huygens project staff, Deep Space Network
  personel and the CIRS instrument and science-planning teams with funding
  provided by NASA/JPL, the UK Particle Physics and Astronomy Council,
  NASA/GSFC and the National Research Council Research Associate Program.

---------------------------------------------------------
Title: Vertical profiles and latitudinal variations of nitrile
    abundances in Titan's atmosphere derived from Cassini/CIRS limb and
    nadir data
Authors: Teanby, N. A.; Irwin, P. G. J.; de Kok, R.; Nixon, C. A.;
   Coustenis, A.; Bézard, B.; Calcutt, S. B.; Bowles, N. E.; Flasar,
   F. M.; Fletcher, L.; Howett, C.; Taylor, F. W.; CIRS Team
2005DPS....37.4102T    Altcode: 2005BAAS...37..707T
  The Cassini/Huygens spacecraft entered orbit around Saturn on
  1<SUP>st</SUP> July 2004. Since then, the Composite InfraRed
  Spectrometer (CIRS) has successfully returned thousands of infrared
  spectra of Titan at resolutions from 0.5--15 cm<SUP>-1</SUP> in the mid-
  and far-IR (10--1400 cm<SUP>-1</SUP> or 1000--7 μ m). This spectral
  region is rich in features from many nitrile compounds, which allows
  their abundance to be retrieved. <P />Nitrile species provide the
  possibility of tracing atmospheric circulation on Titan. One Titan year
  lasts 30 earth years. Therefore, with photochemical lifetimes ranging
  from under a year to tens of years, nitrile abundances can be used
  to probe time scales relevant to atmospheric motion. The observed
  variations can then be compared to predictions from dynamical and
  photochemical models. <P />We have used the limb sounding capabilities
  of CIRS to retrieve vertical profiles of nitrile species, including
  HCN and HC<SUB>3</SUB>N. First, the segment of the mid-IR spectrum
  from 1240-1360 cm<SUP>-1</SUP> was used to retrieve stratospheric
  temperature. Second, sub-spectra were extracted from the 10--800
  cm<SUP>-1</SUP> region and used to obtain vertical profiles of
  nitriles. The limiting vertical resolution of these profiles is
  determined by the field of view size at the tangent height, which
  varies between 10 and 50 km. Profiles from the equator and north polar
  region will be presented. <P />We also discuss the latitude variation
  of nitrile compounds derived from over 18000 nadir spectra selected
  from 2.5 cm<SUP>-1</SUP> resolution mapping sequences taken from July
  2004 to April 2005 and covering 90S to 60N. Contribution functions for
  these observations peak around 3 mbar, well into the stratosphere. HCN,
  HC<SUB>3</SUB>N, and C<SUB>2</SUB>N<SUB>2</SUB> all display a marked
  increase toward the north. HCN displays a 4 fold increase from 0--60N. A
  simple 1D numerical model coupled with the HCN variation implies a
  downwelling velocity of 0.3 mms<SUP>-1</SUP>. The nadir determinations
  will be compared with vertical profiles derived from the limb data.

---------------------------------------------------------
Title: Latitudinal Variation in Temperature and Composition of
    Saturn's Upper Troposphere from Cassini/CIRS as a Tracer For
    Atmospheric Dynamics
Authors: Fletcher, L. N.; Irwin, P. G. J.; Teanby, N.; Orton, G.;
   Parrish, P.; de Kok, R.; Calcutt, S.; Howett, C.; Read, P. L.; Taylor,
   F. W.; Cassini CIRS Team
2005DPS....37.3006F    Altcode: 2005BAAS...37Q.678F
  The presence of the Cassini Huygens spacecraft in the Saturnian
  system provides an unprecedented opportunity to study the dynamics
  of the gas giant in more detail than ever before. Infrared spectra
  from Saturn's southern hemisphere have been obtained by the Composite
  Infrared Spectrometer (CIRS), at both a high (0.5cm<SUP>-1</SUP>) and
  medium (2.5cm<SUP>-1</SUP>) apodized spectral resolution. Latitudinal
  variations of temperature and composition in Saturn's upper troposphere
  are measured using an optimal estimation retrieval code developed
  in Oxford. The far infrared (10-600cm<SUP>-1</SUP>) continuum is
  modelled by varying temperature, para-hydrogen fraction and aerosol
  opacity, with temperature contribution functions sensing pressures
  from 0.1 to 0.5atm. Abundances and fractional scale heights of
  ammonia and phosphine are then retrieved from rotational lines in the
  10-200cm<SUP>-1</SUP> region. The mid infrared (600-1400cm<SUP>-1</SUP>)
  provides temperature profiles from 600-700cm<SUP>-1</SUP>, whilst
  the ν <SUB>4</SUB> fundamental of phosphine at 1118cm<SUP>-1</SUP>
  is used to retrieve a further measure of its abundance. Results
  are compared to global data from the Mid Infrared Spectrometer
  and Imager (MIRSI) instrument on NASA's Infrared Telescope
  Facility. Measurement from filters covering the collision induced
  absorption of hydrogen in the 400-600cm<SUP>-1</SUP> region and the
  ν <SUB>2</SUB> phosphine fundamental near to 1000cm<SUP>-1</SUP>
  were obtained using the same retrieval scheme. <P />The distribution
  of phosphine and ammonia is a balance between vertical transport and
  photochemical destruction. Elevated abundances of these gases are
  used as tracers for regions of upwelling constituent-rich air from
  deeper within the troposphere. Variations in retrieved optical depth
  due to aerosols, and deviations of parahydrogen fraction from local
  thermal equilibrium are also presented. Using an assumed stratospheric
  abundance of methane, the mid infrared spectra were used to obtain
  preliminary measures of the [D]/[H] ratio in methane of (1.96± 0.80)
  × 10<SUP>-5</SUP> and a [<SUP>12</SUP>C]/[<SUP>13</SUP>C] ratio of
  78.5<SUB>-14.0</SUB><SUP>+21.9</SUP>. <P />Acknowledgement: This work
  is funded by the UK Particle Physics and Astronomy Research Council.

---------------------------------------------------------
Title: Titan's Oxygen compound distributions and condensate
    characteristics from Cassini/CIRS observations
Authors: de Kok, R.; Irwin, P. G. J.; Teanby, N. A.; Fletcher, L.;
   Calcutt, S. B.; Howett, C.; Taylor, F. W.; Bowles, N. E.; Cassini
   CIRS Team
2005DPS....37.4508D    Altcode: 2005BAAS...37Q.718D
  The Cassini/CIRS instrument has measured Titan's infrared spectrum
  many times since its arrival at Saturn in July 2004. Observations
  were made both in nadir and in limb geometry, at a wide range of
  latitudes and altitudes. <P />Using nadir and limb data with the
  highest spectral resolution obtainable by CIRS (0.5 cm<SUP>-1</SUP>),
  the stratospheric emission of carbon dioxide at 667 cm<SUP>-1</SUP>
  was analysed. Results of this analysis include the variations of the
  CO<SUB>2</SUB> concentration with latitude, and the variation with
  altitude. The latter is critical for understanding the oxygen chemistry
  in Titan's atmosphere and can constrain the nature of Titan's oxygen
  source. The abundance of CO was also determined and an upper limit was
  set for the H<SUB>2</SUB>O abundance. <P />CIRS has the capability
  to measure, for the first time, the spectral region between 10-200
  cm<SUP>-1</SUP>. This region is mainly dominated by collision induced
  absorption and includes the rotational lines of e.g. CH<SUB>4</SUB>,
  HCN and CO. In this region, at least two broad spectral features were
  also identified, possibly caused by condensates. CIRS data with low
  spectral resolution (15 cm<SUP>-1</SUP>) was used to obtain dependences
  with latitude and altitude of these features, therefore constraining
  their possible sources.

---------------------------------------------------------
Title: Electron Acceleration at Reconnecting X-Points in Solar Flares
Authors: Hamilton, B.; Fletcher, L.; McClements, K. G.; Thyagaraja, A.
2005ApJ...625..496H    Altcode:
  The acceleration of electrons in solar flares is simulated using an
  extended version of a full orbit test-particle code previously used to
  compute losses of fusion alpha particles from tokamaks and to study
  flare proton acceleration. The magnetic and electric fields in the
  model are obtained from solutions of the linearized MHD equations
  for reconnecting modes at a magnetic X-point with zero equilibrium
  current. The magnetic field is assumed to have a small finite
  component perpendicular to the plane of the X-point. The version of
  the code used in the simulations is fully relativistic and includes
  Coulomb collisions. It is demonstrated that electrons cross the system
  boundary at distinct footpoints with the relative numbers and energy
  distribution at each footpoint sensitive to the longitudinal magnetic
  field component and collision time. These results are discussed in
  the context of recent flare observations showing asymmetric hard X-ray
  emission from the chromospheric footpoints of magnetic loops.

---------------------------------------------------------
Title: TRACE and RHESSI observations of white-light flares
Authors: Hudson, H. H.; Metcalf, T.; Wolfson, J.; Fletcher, L.;
   Khan, J.
2005AGUSMSP51C..03H    Altcode:
  TRACE gives a photometrically stable, high-resolution view of the
  visible and UV emissions of solar flares, with enough diagnostic power
  to distinguish photospheric from chromospheric contributions. These
  emissions dominate the radiant energy of a flare and correspond
  well with hard X-ray emission in the impulsive phase. We survey
  these data with reference to well-observed events of 4~October~2002
  and 4~November~2003, on the disk (M4; S19W09) and on the limb (X17;
  S19W83) respectively. We analyze the spatial and temporal properties
  of the footpoint sources in these two events, characterizing their
  physical parameters (contrast, image gradients, apparent motions). The
  brightest kernels of the 4~October~2002 event have intensities twice
  that of the quiet photosphere, and have sizes close to the Nyquist
  limit of the TRACE pixels (0.5~arc~sec). The white-light footpoint
  sources can be considered as a proxy for the target region of fast
  electrons studied via hard X-ray bremsstrahlung. We compare RHESSI
  hard X-ray footpoint sources with their white-light counterparts and
  estimate filling factors for the hard X-ray emission itself.

---------------------------------------------------------
Title: Fip Enhancement by Alfvén Ionization
Authors: Diver, D. A.; Fletcher, L.; Potts, H. E.
2005SoPh..227..207D    Altcode:
  Alfvén ionization is offered as a possible mechanism underlying the
  enhanced population of low first ionization potential (FIP) species
  in the solar corona. In this process, the photospheric flow impinging
  on the magnetic structure of a coronal flux tube collides with, and
  displaces, ions in the magnetised plasma within the flux tube. This
  leads to pockets of charge imbalance that persist due to the impeded
  electron transport perpendicular to the magnetic field. The localised
  electric field then energises electrons to the impact ionization energy
  threshold of low-FIP components in the surface flow. Such species remain
  trapped in the plasma, and drift up the magnetic structure, causing a
  localised population enhancement compared to photospheric levels. We
  find that this mechanism successfully accounts for observed biases for
  flow speeds known to exist in the photosphere, and moreover explains
  certain anomalous abundances which do not fit into existing theories.

---------------------------------------------------------
Title: Multialtitude Observations of a Coronal Jet during the Third
    Whole Sun Month Campaign
Authors: Ko, Y. -K.; Raymond, J. C.; Gibson, S. E.; Alexander, D.;
   Strachan, L.; Holzer, T.; Gilbert, H.; Cyr, O. C. St.; Thompson, B. J.;
   Pike, C. D.; Mason, H. E.; Burkepile, J.; Thompson, W.; Fletcher, L.
2005ApJ...623..519K    Altcode:
  On 1999 August 26, a coronal jet occurred at the northwest limb near
  a sigmoid active region (AR 8668) that was the target for a joint
  observation plan (SOHO joint observing program 106) during the third
  Whole Sun Month Campaign. This jet was observed by several instruments
  at the limb (SOHO/CDS, SOHO/EIT, TRACE, and Mauna Loa Solar Observatory
  CHIP and PICS) and at 1.64 R<SUB>solar</SUB> (SOHO/UVCS). At the limb,
  this jet event displayed both low- and high-temperature components. Both
  high- and low-temperature components were evident during the early phase
  (first 20 minutes) of the event. However, the low-temperature component
  is maintained for ~1 hr after the higher temperature component is
  gone. There is a second brightening (a possible second jet) seen by
  EIT and TRACE about 50 minutes after the onset of the first jet. The
  line-of-sight motion at the limb began with a 300 km s<SUP>-1</SUP>
  redshift and evolved to a 200 km s<SUP>-1</SUP> blueshift. At
  1.64 R<SUB>solar</SUB>, the intensities of Lyα and Lyβ in the jet
  increased by a factor of several hundred compared with the background
  corona. The C III λ977 line also brightened significantly. This
  indicates low-temperature [~(1-2)×10<SUP>5</SUP> K] emission in the
  jet, while the intensities of O VI λ1032 and O VI λ1037 increased
  by as much as a factor of 8. The UVCS data show evidence of heating at
  the early phase of the event. The Doppler shift in the lines indicates
  that the line-of-sight (LOS) velocity in the jet started from ~150
  km s<SUP>-1</SUP> in blueshift and ended at ~100 km s<SUP>-1</SUP>
  in redshift. This LOS motion seen at 1.64 R<SUB>solar</SUB> was
  apparently opposite to what was observed when the jet emerged from the
  limb. The Doppler dimming analysis indicates that the radial outflow
  speed correlates with the magnitude of the LOS speed. Interestingly,
  UVCS observations at 2.33 and 2.66 R<SUB>solar</SUB> show no trace of
  the jet and SOHO/LASCO observations also yield no firm detection. We
  find that a simple ballistic model can explain most of the dynamical
  properties of this jet, while the morphology and the thermal properties
  agree well with reconnection-driven X-ray jet models.

---------------------------------------------------------
Title: Rhessi Microflare Statistics
Authors: Hannah, I. G.; Christe, S.; Krucker, S.; Hudson, H. S.;
   Fletcher, L.; Hendry, M. A.
2004ESASP.575..259H    Altcode: 2004soho...15..259H
  No abstract at ADS

---------------------------------------------------------
Title: On the Role of Fast Shocks in Creating Relativistic Electrons
    in the Solar Corona
Authors: Hesse, M.; Fletcher, L.; Neukirch, T.
2004AGUFMSH24A..05H    Altcode:
  The existence of fast shocks, at the interface between reconnection
  outflow jets and underlying magnetic loops, has been suggested by a
  number of researchers. Should they exist, fast shocks would provide
  an effective mechanism to convert a large fraction of the combined
  kinetic energy in the reconnection outflow into thermal energy of the
  shocked plasma. Since this process affects directly a large number of
  particles, it may provide a solution to the problem of explaining the
  number of electrons that are apparently involved in the generation
  of the high-energy X-ray signatures observed by RHESSI. In order
  to investigate this possibility further, we present the results of
  fully-electromagnetic, relativistic, particle-in-cell simulations
  of fast shock structure and evolution. In particular, we discuss the
  effect on downstream nonthermal electrons of parameters such as Mach
  number, plasma beta, and the angle between shock normal and the upstream
  magnetic field. We will compare our results to earlier kinetic studies
  of fast shocks, and provide an evaluation of the shock mechanism as a
  means to explain nonthermal, relativistic electron distributions such
  as expected in conjunction with RHESSI X-ray events.

---------------------------------------------------------
Title: The hard X-ray spectral structure of flare ribbons
Authors: Hudson, H.; Fletcher, L.; Krucker, S.; Pollock, J.
2004AGUFMSH24A..02H    Altcode:
  We examine the spatial distribution of hard X-ray spectral parameters
  in flares exhibiting the classic two-ribbon structure using RHESSI
  observations. The flares studied include July~15 and July~17, 2002,
  and October~29, 2003. We confirm the existence of a tendency for
  the localization of the hard X-ray sources into dominant bright
  “footpoint” regions which do not show ribbon structure as extensive
  as that seen in Hα or UV~images. As a part of the study we characterize
  the ribbons photometrically in the EUV as observed by TRACE, confirming
  earlier results that find complicated relationships between EUV and
  hard X-rays. We seek an empirical explanation for the restricted
  hard X-ray footpoints in terms of a spatial analog of the well-known
  “soft-hard-soft” morphology: the regions of weaker hard X-ray emission
  correspond to steeper X-ray energy spectra and hence to softer electron
  precipitation spectra. This relationship may be as predicted by the
  1D radiation hydrodynamics models of flaring loops.

---------------------------------------------------------
Title: Overview of Solar Flares
Authors: Hudson, Hugh; Fletcher, Lyndsay; Khan, Josef I.; Kosugi, Takeo
2004ASSL..314..153H    Altcode:
  This chapter reviews the physics of solar flares, with special emphasis
  on the past decade. During this decade first Yohkoh and then TRACE
  have drastically improved our observational capabilities for flares,
  with contributions also from the essentially non-flare instrumentation
  on SOHO and of course the ground-based observatories. In this review
  we assess how these new observations have changed our understanding
  of the basic physics of flares and consider the implications of these
  results for future observations with FASR. The discussion emphasizes
  flaring loops, flare ejecta, particle acceleration, and microflares.

---------------------------------------------------------
Title: Tracking of TRACE Ultraviolet Flare Footpoints
Authors: Fletcher, Lyndsay; Pollock, Jennifer A.; Potts, Hugh E.
2004SoPh..222..279F    Altcode:
  Solar flares produce bright, compact sources of UV emission in the
  lower atmosphere, identified as flare footpoints. Observed at high time
  cadence with the Transition Region and Coronal Explorer, groups of UV
  footpoints define flare `ribbons' which move as the flare progresses. We
  have developed a procedure to track individual bright kernels within
  flare ribbons, enabling us to study the motion of these sites of
  excitation through the solar chromosphere. We have applied this to a
  flare observed by TRACE in the 1600 Å passband at 2-s cadence. In this
  event, the footpoints have an average speed of 15 km s<SUP>−1</SUP>,
  with a superposed random `meandering' component, consistent with the
  footpoint magnetic field being anchored around the edges of granular
  cells. Examining the brightness as a function of time, we find that
  the timing of peaks in brightness is significantly correlated with
  the timing of peaks in the product of the footpoint speed with the
  line-of-sight magnetic field strength at the footpoint location;
  in other words with a measure of the coronal reconnection rate.

---------------------------------------------------------
Title: Electron Inertial Effects on Rapid Energy Redistribution at
    Magnetic X-Points
Authors: McClements, K. G.; Thyagaraja, A.; Ben Ayed, N.; Fletcher, L.
2004ApJ...609..423M    Altcode: 2004astro.ph..1573M
  The evolution of nonpotential perturbations to a current-free
  magnetic X-point configuration is studied, taking into account
  electron inertial effects as well as resistivity. Electron inertia
  is shown to have a negligible effect on the evolution of the system
  whenever the collisionless skin depth is less than the resistive scale
  length. Nonpotential magnetic field energy in this resistive MHD limit
  initially reaches equipartition with flow energy, in accordance with
  ideal MHD, and is then dissipated extremely rapidly on an Alfvénic
  timescale that is essentially independent of Lundquist number. In
  agreement with resistive MHD results obtained by previous authors, the
  magnetic field energy and kinetic energy are then observed to decay on
  a longer timescale and exhibit oscillatory behavior, reflecting the
  existence of discrete normal modes with finite real frequency. When
  the collisionless skin depth exceeds the resistive scale length, the
  system again evolves initially according to ideal MHD. At the end of
  this ideal phase, the field energy decays typically on an Alfvénic
  timescale, while the kinetic energy (which is equally partitioned
  between ions and electrons in this case) is dissipated on the electron
  collision timescale. The oscillatory decay in the energy observed in
  the resistive case is absent, but short-wavelength structures appear
  in the field and velocity profiles, suggesting the possibility of
  particle acceleration in oppositely directed current channels. The
  model provides a possible framework for interpreting observations of
  energy release and particle acceleration on timescales down to less
  than a second in the impulsive phase of solar flares.

---------------------------------------------------------
Title: Meeting report: Core to corona: UKSP 2004
Authors: Fletcher, Lyndsay; Erdelyi, Robert
2004A&G....45c..33F    Altcode:
  The UK solar physics community gathered with the MIST community in
  Edinburgh from 29 March - 1 April 2004, with a programme that reflected
  the strength and diversity of UK research in the field. Lyndsay Fletcher
  and Robert Erdelyi report.

---------------------------------------------------------
Title: The hard X-ray spectral structure of flare ribbons
Authors: Fletcher, L.; Hudson, H. S.; Krucker, S.; Pollock, J. A.
2004AAS...204.5403F    Altcode: 2004BAAS...36..758F
  We examine the spatial distribution of hard X-ray spectral parameters
  in flares exhibiting the classic two-ribbon structure using RHESSI
  observations. The flares studied include July 15 and July 17, 2002,
  and October 29, 2003. We confirm the existence of a tendency for
  the localization of the hard X-ray sources into dominant bright
  “footpoint” regions which do not show ribbon structure as extensive
  as that seen in Hα or UV images. As a part of the study we characterize
  the ribbons photometrically in the EUV as observed by TRACE, confirming
  earlier results that find complicated relationships between EUV and
  hard X-rays. We seek an empirical explanation for the restricted
  hard X-ray footpoints in terms of a spatial analog of the well-known
  “soft-hard-soft” morphology: the regions of weaker hard X-ray emission
  correspond to steeper X-ray energy spectra and hence to softer electron
  precipitation spectra. This relationship may be as predicted by the
  1D radiation hydrodynamics models of flaring loops.

---------------------------------------------------------
Title: Multi-Altitude Observations of a Coronal Jet
Authors: Ko, Y. -K.; Raymond, J. C.; Gibson, S. E.; Alexander, D.;
   Strachan, L.; Holzer, T.; Gilbert, H.; St. Cyr, O. C.; Thompson,
   B. J.; Pike, C. D.; Burkepile, J.; Thompson, W.; Fletcher, L.
2004AAS...204.5413K    Altcode: 2004BAAS...36..759K
  A coronal jet occurred on August 26, 1999 at the NW limb near a sigmoid
  active region (AR8668). This jet was observed by several instruments
  at the limb (SOHO/CDS, SOHO/EIT, TRACE, MLSO/CHIP, MLSO/PICS) and
  at 1.64 Ro (SOHO/UVCS). At the limb, this jet event has both low and
  high temperature components. The high temperature component appeared
  at the early phase (first 20 minutes) of the event along with the low
  temperature component while the latter seems to last long ( ∼ 1 hour)
  after the higher temperature component was gone. The line-of-sight
  motion at the limb started with red-shifted (by as much as 300 km/s)
  and turned blue-shifted (by as much as 200 km/s). At 1.64 Ro, the
  intensities of Lyα , Lyβ in the jet increased by a factor of several
  hundreds compared with the background corona. C III λ 977 line also
  brightened significantly. This indicates low temperature ( ∼ 1-2×
  10<SUP>5</SUP> K) emission in the jet, while the intensities of O VI
  λ 1032 and O VI λ 1037 increased by a factor of as large as 8. Both
  UVCS and CDS data show evidence of heating at the early phase of the
  event. The line-of-sight velocity seen at 1.64 Ro started with ∼ 150
  km/sec in blue shift and ended at ∼ 100 km/sec in red shift. This is
  apparently opposite to what were observed when the jet emerged from
  the limb. The Doppler dimming analysis indicates that the radial
  outflow speed correlates with the magnitude of the line-of-sight
  speed. Interestingly, UVCS observations at 2.33 and 2.66 Ro show no
  trace of the jet and LASCO observations also yield no firm sight of the
  jet. In this paper, we present the observations by these instruments
  and discuss the dynamical structure and physical properties of this
  jet. Y.-K. Ko acknowledges the support by NASA grant NAG5-12865.

---------------------------------------------------------
Title: Electron inertia modifications to X-point reconnection in
    solar flares
Authors: McClements, K. G.; Thyagaraja, A.; Ben Ayed, N.; Fletcher, L.
2004cosp...35.1242M    Altcode: 2004cosp.meet.1242M
  The evolution of perturbations to a current-free magnetic X-point
  is studied as a paradigm for short timescale energy release in
  solar flares, taking into account electron inertia as well as
  resistivity. Electron inertia is found to have a negligible effect
  whenever the collisionless skin depth is less than the resistive scale
  length. Non-potential magnetic field energy in this resistive MHD limit
  initially reaches equipartition with flow energy, in accordance with
  ideal MHD, and is then dissipated extremely rapidly, on an Alfvénic
  timescale that is essentially independent of Lundquist number. In
  agreement with resistive MHD results obtained by previous authors [1],
  the magnetic field energy and kinetic energy are then observed to decay
  on a longer timescale and exhibit oscillatory behavior, reflecting the
  existence of discrete normal modes with finite real frequency. When the
  collisionless skin depth exceeds the resistive scale length, the field
  energy again decays on an Alfvénic timescale, while the kinetic energy
  (which is equally partitioned between ions and electrons in this case)
  decays on the electron collision timescale. In this regime filaments
  appear in the field and velocity profiles, suggesting the possibility
  of particle acceleration in oppositely-directed current channels and
  symmetrical precipitation out of the acceleration region. Both the rapid
  decay in field energy and the filamentation process arise from phase
  mixing associated with a continuous eigenmode spectrum that replaces
  the discrete resistive MHD spectrum [2]. Because of the Alfvénic
  timescale of the field decay, very modest perturbation amplitudes are
  sufficient for the corresponding inductive electric fields to produce
  hard X-ray emitting electrons on sub-second timescales. The model thus
  provides a framework for interpreting observations of short timescale
  energy release and particle acceleration in the impulsive phase of
  flares. This work was supported by the United Kingdom Engineering
  and Physical Sciences Research Council [1] Craig I. J. D. &amp;
  Watson P. G. Astrophys. J 393, 385 (1992) [2] McClements K. G. &amp;
  Thyagaraja A. Plasma Phys. Control. Fusion 46, 39 (2004)

---------------------------------------------------------
Title: Hubble Goes IMAX: 3D Visualization of the GOODS Southern
    Field for a Large Format Short Film
Authors: Summers, F. J.; Stoke, J. M.; Albert, L. J.; Bacon, G. T.;
   Barranger, C. L.; Feild, A. R.; Frattare, L. M.; Godfrey, J. P.;
   Levay, Z. G.; Preston, B. S.; Fletcher, L. M.; GOODS Team
2003AAS...203.8603S    Altcode: 2003BAAS...35.1345S
  The Office of Public Outreach at the Space Telescope Science Institute
  is producing a several minute IMAX film that will have its world
  premiere at the January 2004 AAS meeting. The film explores the rich
  tapestry of galaxies in the GOODS Survey Southern Field in both two
  and three dimensions. This poster describes the visualization efforts
  from FITS files through the galaxy processing pipeline to 3D modelling
  and the rendering of approximately 100 billion pixels. The IMAX film
  will be shown at a special session at Fernbank Science Center, and
  the video will be shown at the STScI booth.

---------------------------------------------------------
Title: UKSP: Solar physics in Dublin
Authors: Erdélyi, R.; Fletcher, L.; Doyle, G. J.
2003A&G....44c..13E    Altcode:
  This year's annual UK Solar Physics meeting took place in Dublin from
  7-11 April 2003, overlapping with the National Astronomy Meeting. R
  Erdélyi, L Fletcher and G J Doyle summarize.

---------------------------------------------------------
Title: Field-Guided Proton Acceleration at Reconnecting x-Points
    in Flares
Authors: Hamilton, B.; McClements, K. G.; Fletcher, L.; Thyagaraja, A.
2003SoPh..214..339H    Altcode: 2003astro.ph..1359H
  An explicitly energy-conserving full orbit code CUEBIT, developed
  originally to describe energetic particle effects in laboratory fusion
  experiments, has been applied to the problem of proton acceleration
  in solar flares. The model fields are obtained from solutions of the
  linearised MHD equations for reconnecting modes at an X-type neutral
  point, with the additional ingredient of a longitudinal magnetic field
  component. To accelerate protons to the highest observed energies
  on flare timescales, it is necessary to invoke anomalous resistivity
  in the MHD solution. It is shown that the addition of a longitudinal
  field component greatly increases the efficiency of ion acceleration,
  essentially because it greatly reduces the magnitude of drift motions
  away from the vicinity of the X-point, where the accelerating component
  of the electric field is largest. Using plasma parameters consistent
  with flare observations, we obtain proton distributions extending up
  to γ-ray-emitting energies (&gt; 1 MeV). In some cases the energy
  distributions exhibit a bump-on-tail in the MeV range. In general,
  the shape of the distribution is sensitive to the model parameters.

---------------------------------------------------------
Title: RHESSI Workshop Reports: Multiwavelength Correlative Studies
    of RHESSI events
Authors: Fletcher, L.; RHESSI Workshop Series Working Group 4 Team
2003SPD....34.1402F    Altcode: 2003BAAS...35..829F
  In this talk we will report on the projects and progress of RHESSI
  Working Group 4, 'Multi-Wavelength Correlative Studies'. The remit of
  this working group is to use diagnostics from space and ground-based
  instrumentation in tandem with RHESSI to further our understanding
  of the fast particles and plasmas produced during large and small
  flaring events, and to illuminate the magnetic environment in which
  these take place. Topics being studied include the Neupert effect,
  hot coronal sources and coronal mass motions, and flare footpoint
  evolution. The April 21st 2002 X1.5 flare is a focus for much of the
  group's activities. This event has excellent multiwavelength coverage
  and shows many interesting features such as coronal downflows, moving
  RHESSI coronal sources, and very compact hard X-ray footpoints.

---------------------------------------------------------
Title: The Energy Release Process in Solar Flares; Constraints from
    TRACE Observations
Authors: Fletcher, L.; Warren, H. P.
2003LNP...612...58F    Altcode: 2003ecpa.conf...58F
  The Transition Region And Coronal Explorer Satellite, TRACE, launched
  in 1998, has proved a valuable tool in the study of solar flares. UV
  and EUV observations of the impulsive and gradual phases of many tens
  of flares have been made. TRACE's excellent spatial resolution and
  image cadence on the order of one second allow the rearrangement of the
  magnetic field to be tracked in some detail. The combination of these
  observations with data from other instruments, and with magnetic field
  reconstructions, have provided strong evidence for (a) UV emission as a
  beam proxy in the impulsive phase (b) long duration coronal heating in
  the gradual phase (c) very complex and varied magnetic geometries. We
  review the observational evidence for the above, discussing implications
  for energy release.

---------------------------------------------------------
Title: Charged particle dynamics in X-type neutral points
Authors: Hamilton, B.; Fletcher, L.; McClements, K. G.; Thyagaraja, A.
2002ESASP.506..291H    Altcode: 2002svco.conf..291H; 2002ESPM...10..291H
  We have developed a novel algorithm for the calculation of test
  particle orbits in electromagnetic fields. We have applied this
  to the problem of determining ion and electron orbits in an X-type
  magnetic configuration, of a type that may occur during reconnection
  in the corona above a flaring region. Particles in our simulation gain
  energy through interaction with the normal modes of oscillation of the
  X-type structure. We find that the addition of a longitudinal magnetic
  field component to a model proposed by Craig and McClymont [ApJ 371,
  L41 (1991)] produces a much greater efficiency in accelerating
  protons. Results of different simulations are presented and the
  sensitivity of the results to the parameters of the magnetic environment
  is discussed.

---------------------------------------------------------
Title: Chaotic dynamics and collisionless reconnection at an X-type
    neutral point
Authors: Hannah, Iain G.; Fletcher, Lyndsay; Hendry, Martin A.
2002ESASP.506..295H    Altcode: 2002svco.conf..295H; 2002ESPM...10..295H
  The chaotic dynamics of test particle orbits in a magnetic X-type
  neutral point have been investigated through the use of Lyapunov
  Characteristic Exponents (LCE), with the aim of solving the Pesin
  Identity (sum of the positive LCE) as a Monte Carlo integration
  problem. Treating the identity in this manner allows the phase space
  of a system to be intelligently sampled for the most chaotic orbits,
  as these orbits contribute most to the integral. This analysis so
  far has concentrated on how the chaotic behaviour relates to particle
  acceleration and energy gain, with future work to examine whether the
  chaos can produce an "anomalous resistivity" affecting the reconnection
  rate.

---------------------------------------------------------
Title: Energetic particles in the solar atmosphere
Authors: Fletcher, Lyndsay
2002ESASP.506..223F    Altcode: 2002svco.conf..223F; 2002ESPM...10..223F
  This article reviews the evidence for, and the nature of, accelerated
  particles in the lower solar atmosphere. Particle distributions with
  significantly non-thermal components are ubiquitous throughout the
  solar atmosphere, and we concentrate primarily on those arising in
  solar flares. We mention the main diagnostics for accelerated flare
  electrons and ions, and discuss the more popular theoretical ideas
  regarding their acceleration.

---------------------------------------------------------
Title: Mapping RHESSI footpoints with potential-field models
Authors: Fletcher, L.; Hudson, H. S.; Metcalf, T. R.
2002AGUFMSH52A0452F    Altcode:
  RHESSI hard X-ray observations help us to identify the locations of
  magnetically conjugate footpoints, and to study their apparent motions
  during the evolution of the impulsive phase of a flare. We put this
  information into the context of an M-class flare that occurred 2002
  March 14 01:50 UT (GOES peak time) at S12, E23 (NOAA region 9866) by
  making potential-field mappings of the coronal magnetic structure. In
  principle the hard X-ray sources (plus the mapping) constrain the
  site of magnetic energy release, and the maps reveal the location
  of the stored energy. The RHESSI source centroids can be determined
  to better than 1” (rms) for an M-class flare. This analysis is an
  exploration of the feasibility of such an approach, since full success
  would require understanding the magnetic restructuring in detail. If
  suitable X-class RHESSI flares occur we will be able to present data
  with better precision.

---------------------------------------------------------
Title: Spectral and Spatial Variations of Flare Hard X-ray Footpoints
Authors: Fletcher, L.; Hudson, H. S.
2002SoPh..210..307F    Altcode:
  In a sample of strong RHESSI M-class flares we have made a study of
  the relationship between the `hardness' of the HXR spectrum and the
  intensity in the 30-50 keV energy range. In all events we find clear
  evidence for a `soft-hard-soft' pattern of correlation between hardness
  and flux, on time scales as short as 10 s. We investigate whether or
  not this pattern is intrinsic to the acceleration mechanism. The RHESSI
  images in this energy range are dominated by footpoint brightenings,
  and we have searched for a correlation between footpoint separation
  velocity and spectral hardness, to be compared qualitatively with
  theoretical flare models. We find quite systematic footpoint motions,
  and also note that episodes in which footpoint separation varies
  rapidly often correspond with episodes of significant change in the
  flare spectral index, though not as the simplest flare models would
  predict. We report also on one of our events, on 14 March 2002, which
  exhibits highly sheared HXR footpoint ribbons extending over a scale
  of 100 arc sec. For this flare we find a correlation between footpoint
  motion and hard X-ray flux.

---------------------------------------------------------
Title: Magnetic flux ropes: Would we know one if we saw one?
Authors: Gibson, S. E.; Low, B. C.; Leka, K. D.; Fan, Y.; Fletcher, L.
2002ESASP.505..265G    Altcode: 2002IAUCo.188..265G; 2002solm.conf..265G
  There has been much debate lately about whether twisted magnetic flux
  ropes exist in the corona. When asked for observational evidence
  of them, the temptation is to show images of apparently twisted
  structures. However, we must be very careful of projection effects in
  interpreting these observations. Two critical aspects of understanding
  how we might observe flux ropes are 1) the 3D nature of the flux rope,
  and 2) physically, which bits are visible and for what reasons? In
  this paper we will use a simple but physically reasonable 3D analytic
  model to address these two issues, and develop techniques that can in
  future be used on more general models, both analytic and numerical.

---------------------------------------------------------
Title: High-energy solar radiation with RHESSI
Authors: Fletcher, L.
2002Obs...122..249F    Altcode:
  No abstract at ADS

---------------------------------------------------------
Title: The Structure and Evolution of a Sigmoidal Active Region
Authors: Gibson, S. E.; Fletcher, L.; Del Zanna, G.; Pike, C. D.;
   Mason, H. E.; Mandrini, C. H.; Démoulin, P.; Gilbert, H.; Burkepile,
   J.; Holzer, T.; Alexander, D.; Liu, Y.; Nitta, N.; Qiu, J.; Schmieder,
   B.; Thompson, B. J.
2002ApJ...574.1021G    Altcode:
  Solar coronal sigmoidal active regions have been shown to be precursors
  to some coronal mass ejections. Sigmoids, or S-shaped structures,
  may be indicators of twisted or helical magnetic structures, having
  an increased likelihood of eruption. We present here an analysis of a
  sigmoidal region's three-dimensional structure and how it evolves in
  relation to its eruptive dynamics. We use data taken during a recent
  study of a sigmoidal active region passing across the solar disk
  (an element of the third Whole Sun Month campaign). While S-shaped
  structures are generally observed in soft X-ray (SXR) emission, the
  observations that we present demonstrate their visibility at a range of
  wavelengths including those showing an associated sigmoidal filament. We
  examine the relationship between the S-shaped structures seen in SXR
  and those seen in cooler lines in order to probe the sigmoidal region's
  three-dimensional density and temperature structure. We also consider
  magnetic field observations and extrapolations in relation to these
  coronal structures. We present an interpretation of the disk passage
  of the sigmoidal region, in terms of a twisted magnetic flux rope
  that emerges into and equilibrates with overlying coronal magnetic
  field structures, which explains many of the key observed aspects of
  the region's structure and evolution. In particular, the evolving flux
  rope interpretation provides insight into why and how the region moves
  between active and quiescent phases, how the region's sigmoidicity is
  maintained during its evolution, and under what circumstances sigmoidal
  structures are apparent at a range of wavelengths.

---------------------------------------------------------
Title: Emergence of twisted magnetic flux into the corona
Authors: Gibson, S.; Low, B. C.; Fan, Y.; Fletcher, L.
2002AAS...200.3603G    Altcode: 2002BAAS...34..693G
  The interaction between emerging magnetic structures and preexisting
  overlying coronal structures will be addressed using a combination of
  observations and physical models that incorporate a range of twisted
  magnetic topologies. Solar explosive events such as coronal mass
  ejections (CMEs) and flares are commonly considered to be driven by
  the free magnetic energy stored in twisted (current carrying) coronal
  magnetic fields. Understanding the origin and the three-dimensional
  nature of these twisted coronal magnetic structures is a crucial step
  towards explaining and predicting CMEs and flares. One possible and
  appealing picture is that the twisted coronal magnetic structures
  form as a result of the emergence of twisted magnetic flux tubes
  from the solar interior. We might imagine a scenario where a flux
  rope forms sub-photospherically, emerges through the photosphere,
  exists in the corona until it loses its stability and erupts in a
  CME which moves out through interplanetary space until ultimately
  impacting on the Earth's magnetosphere. Attractively simple as this
  picture is, reality is likely to be more complicated since the various
  regimes are physically very different and pre-existing structures
  would get in the way of our traveling flux rope. We will concentrate
  on joining up two of these regimes, by considering how a flux rope
  could rise from beneath the photosphere and emerge into the corona,
  interacting with pre-existing coronal structures. We will approach this
  problem by using a combination of numerical models of the flux rope
  emergence from beneath the photosphere, analytic models of coronal
  dynamic and equilibrium magnetic structures, and photospheric and
  coronal observations of the 3-d structure and evolution of a so-called
  "sigmoidal", or S-shaped active region. In so doing we hope to gain
  essential insight into how twisted magnetic fields are formed and how
  they could be ultimately removed from the solar corona.

---------------------------------------------------------
Title: 2-ribbon flares: observations vs. models
Authors: Fletcher, Lyndsay
2002ocnd.confE..10F    Altcode:
  No abstract at ADS

---------------------------------------------------------
Title: The Magnetic Structure and Generation of EUV Flare Ribbons
Authors: Fletcher, L.; Hudson, H.
2001SoPh..204...69F    Altcode:
  The `ribbons' of two-ribbon flares show complicated patterns reflecting
  the linkages of coronal magnetic field lines through the lower solar
  atmosphere. We describe the morphology of the EUV ribbons of the July
  14, 2000 flare, as seen in SOHO, TRACE, and Yohkoh data, from this
  point of view. A successful co-alignment of the TRACE, SOHO/MDI and
  Yohkoh/HXT data has allowed us to locate the EUV ribbon positions on
  the underlying field to within ∼ 2”, and thus to investigate the
  relationship between the ribbons and the field, and also the sites
  of electron precipitation. We have also made a determination of the
  longitudinal magnetic flux involved in the flare reconnection event,
  an important parameter in flare energetic considerations. There are
  several respects in which the observations differ from what would be
  expected in the commonly-adopted models for flares. Firstly, the flare
  ribbons differ in fine structure from the (line-of-sight) magnetic
  field patterns underlying them, apparently propagating through regions
  of very weak and probably mixed polarity. Secondly, the ribbons split
  or bifurcate. Thirdly, the amount of line-of-sight flux passed over by
  the ribbons in the negative and positive fields is not equal. Fourthly,
  the strongest hard X-ray sources are observed to originate in stronger
  field regions. Based on a comparison between HXT and EUV time-profiles
  we suggest that emission in the EUV ribbons is caused by electron
  bombardment of the lower atmosphere, supporting the hypothesis that
  flare ribbons map out the chromospheric footpoints of magnetic field
  lines newly linked by reconnection. We describe the interpretation of
  our observations within the standard model, and the implications for
  the distribution of magnetic fields in this active region.

---------------------------------------------------------
Title: Numerical Modelling of Trapped Electrons in an Expanding
    Solar Loop
Authors: Fletcher, L.; Hudson, H.
2001AGUFMSH42A0777F    Altcode:
  Recent observations with the Yohkoh Hard X-ray telescope and the
  Nobeyama Radioheliograph [Hudson et al., 2001] have shown a moving
  hard X-ray coronal source, associated in space and time with moving
  microwave and decimeter sources. Because of the electron energies
  involved in producing these emissions, we hypothesize that the
  radiation indicates the presence of a coronal population of high
  energy electrons, trapped in a magnetic loop which is expanding
  outward. The expansion will lead to a `betatron' deceleration effect,
  which, combined with the normal Coulomb scattering and energy losses,
  will lead to an evolution of the particle energy density, spectrum and
  pitch angle distribution. We model this process using a stochastic
  test particle simulation. &gt;http://isass1.solar.isas.ac.jp/
  ~hudson/drafts/apr18.pdf&lt;/a&gt;

---------------------------------------------------------
Title: A Relationship Between Transition Region Brightenings,
    Abundances, and Magnetic Topology
Authors: Fletcher, Lyndsay; López Fuentes, Marcelo C.; Mandrini,
   Cristina H.; Schmieder, Brigitte; Démoulin, Pascal; Mason, Helen E.;
   Young, Peter R.; Nitta, Nariaki
2001SoPh..203..255F    Altcode:
  We present multi-instrument observations of active region (AR) 8048,
  made between 3 June and 5 June 1997, as part of the SOHO Joint Observing
  Program 33. This AR has a sigmoid-like global shape and undergoes
  transient brightenings in both soft X-rays and transition region
  (TR) lines. We compute a magneto-hydrostatic model of the AR magnetic
  field, using as boundary condition the photospheric observations of
  SOHO/MDI. The computed large-scale magnetic field lines show that the
  large-scale sigmoid is formed by two sets of coronal loops. Shorter
  loops, associated with the core of the SXT emission, coincide with
  the loops observed in the hotter CDS lines. These loops reveal a
  gradient of temperature, from 2 MK at the top to 1 MK at the ends. The
  field lines most closely matching these hot loops extend along the
  quasi-separatrix layers (QSLs) of the computed coronal field. The TR
  brightenings observed with SOHO/CDS can also be associated with the
  magnetic field topology, both QSL intersections with the photosphere,
  and places where separatrices issuing from bald patches (sites where
  field lines coming from the corona are tangent to the photosphere)
  intersect the photosphere. There are, furthermore, suggestions that
  the element abundances measured in the TR may depend on the type
  of topological structure present. Typically, the TR brightenings
  associated with QSLs have coronal abundances, while those associated
  with BP separatrices have abundances closer to photospheric values. We
  suggest that this difference is due to the location and manner in which
  magnetic reconnection occurs in two different topological structures.

---------------------------------------------------------
Title: Evidence for the Flare Trigger Site and Three-Dimensional
    Reconnection in Multiwavelength Observations of a Solar Flare
Authors: Fletcher, L.; Metcalf, T. R.; Alexander, D.; Brown, D. S.;
   Ryder, L. A.
2001ApJ...554..451F    Altcode:
  Based on a multiwavelength data set and a topological model for
  the magnetic field, we argue that a M1.9 flare which occurred on
  1993 May shows evidence of three-dimensional coronal reconnection
  in a spine-fan configuration. Images from the Transition Region and
  Coronal Explorer allow the detailed examination of the structures
  involved in the flare and preflare in the 171 Å (1 MK) EUV passband
  and the Lyα (10,000-20,000 K) passband. Yohkoh Hard X-ray Telescope
  maps the position of nonthermal electron precipitation and the
  Soft X-ray Telescope reveals preflare and flare heating on large
  and small scales. While the flare appears to be driven by changes in
  small-scale field close to the photosphere, near the interface between
  strong opposite magnetic polarities, the result is the disruption of
  large-scale field. We demonstrate how this observed activity on large
  and small scales, along with many other aspects of the flare, suggests
  a qualitative explanation in the three-dimensional reconfiguration of
  coronal magnetic field, following a small-scale flux cancellation at
  the photosphere.

---------------------------------------------------------
Title: Ribbons and field at high resolution
Authors: Fletcher, L.; Hudson, H. S.
2001AGUSM..SH31D10F    Altcode:
  The TRACE data let us define the geometry of flare ribbons with great
  precision, as for example in the Bastille Day 2000 flare. We study the
  UV and EUV ribbon motions for this event in comparison with the loops
  seen by SXT and in the TRACE high-temperature response, and compare
  these also with the photospheric magnetic field as observed by MDI. In
  this work we assume the standard model for large-scale coronal magnetic
  reconnection as a source of flare energy, and search for a correlation
  between footpoint locations, magnetic field strength and flare energy
  release as measured by hard X-ray emission.

---------------------------------------------------------
Title: CDS UV Brightenings Explained by Quasi-separatrices and Bald
    Patches in an S-shape active region
Authors: Schmieder, B.; Démoulin, P.; Fletcher, L.; López Fuentes,
   M. C.; Mandrini, C. H.; Mason, H. E.; Young, P. R.; Nitta, N.
2001IAUS..203..314S    Altcode:
  We present multi-instrument observations of AR 8048, made between
  June 3 and June5 1997 as part of SoHO JOP033. This active region
  has a sigmoid-like global shape and undergoes transient erupting
  phenomena which releases the stored energy. Using a force free
  field approach, we defined coronal magnetic field lines which fit
  with the observations. The large-scale magnetic field lines confirms
  the sigmoid characteristics of the active region. The study in 3D of
  the configuration explained where and how the energy is released at
  different places. The Ne VI brightenings correspond to the location
  of tangent to the photosphere field lines, named "bald patch", they
  are localized in the low transition region and represent feet of field
  lines. The Si XII brightenings at coronal temperature are at the top
  of coronal loops joining quasi-separatrices.

---------------------------------------------------------
Title: SOHO/UVCS Observations of a Coronal Jet During the Third
    Whole Sun Month Campaign
Authors: Ko, Y. -K.; Raymond, J.; Gibson, S.; Strachan, L.; Alexander,
   D.; Fletcher, L.; Holzer, T.; Gilbert, H.; Burkepile, J.; St. Cyr,
   C.; Thompson, B.
2000SPD....31.0271K    Altcode: 2000BAAS...32R.823K
  On August 26 1999, a coronal jet occurred at the north west limb
  near a sigmoid active region which has been the target for a joint
  observation plan during the third Whole Sun Month Campaign. This jet
  was observed by several instruments at the limb (SOHO/CDS, SOHO/EIT,
  TRACE, MLSO/CHIP, MLSO/PICS), at 1.7 Ro (SOHO/UVCS), and at the outer
  corona (SOHO/LASCO). At 1.7 Ro, the intensities of Lyman alpha, Lyman
  beta in the jet increased by as large a factor of 100 compared with the
  background corona, while those for O VI 1032 and O VI 1037 increased
  by a factor of 2. C III 977 line also brightened significantly. The
  line shift in the lines indicates that the line-of-sight velocity in
  the jet started from 150 km/sec blue shift and ended at 120 km/sec
  red shift. This line-of-sight motion seen at 1.7 Ro apparently was
  opposite that observed when the jet emerged from the limb. In this
  paper, we present the observation by SOHO/UVCS and discuss the dynamic
  structure and physical properties of this jet as it passed through
  1.7 Ro. Comparisons will be shown with the observations from other
  instruments. This work is supported by NASA Grant number NAG5-7822.

---------------------------------------------------------
Title: Evidence for the Flare Trigger Site and 3-D Reconnection in
    Multi-Wavelength Observations of a Solar Flare
Authors: Metcalf, T. R.; Fletcher, L.; Alexander, D.; Brown, D. S.;
   Ryder, L. A.
2000SPD....31.0261M    Altcode: 2000BAAS...32..822M
  Based on a multi-wavelength data set and a topological model for the
  magnetic field, we argue that a M1.9 flare which occurred on 3-May-99
  shows evidence of 3-d reconnection through a coronal null. Images
  from the Transition Region and Coronal Explorer allow the detailed
  examination of the structures involved in the flare and pre-flare in
  the 171 Angstroms (1MK) EUV passband, and the Lyman α (10,000-20,000K)
  passband. Yohkoh Hard X-ray Telescope maps the position of non-thermal
  electron precipitation and the Soft X-ray Telescope reveals pre-flare
  and flare heating on large and small-scales. While the flare appears
  to trigger in small scale field close to the photosphere, near the
  interface between strong opposite magnetic polarities, the large-scale
  field is directly involved in or affected by all phases of the flare. We
  demonstrate how this observed activity on large and small scales, along
  with many other aspects of the flare find a qualitative explanation
  in the three-dimensional reconfiguration of coronal magnetic field,
  following a small-scale flux cancelation at the photosphere. This
  work is supported by the TRACE and SXT projects at LMSAL (contract
  NAS5-38099 and NAS8-40801).

---------------------------------------------------------
Title: Observations of H-alpha Polarization in Flares
Authors: Mickey, D. L.; Metcalf, T. R.; Fletcher, L.
2000SPD....31.0255M    Altcode: 2000BAAS...32R.820M
  Max Millennium Coordinated Observing Plan #006 has as its goal the
  measurement of H-alpha linear polarization, a possible signature of
  low-energy proton beams in solar flares. Such observations have been
  attempted in the past, but the results were inconclusive. A campaign
  involving Mees Solar Observatory and Big Bear Solar Observatory,
  together with Yohkoh, SOHO and TRACE spacecraft, was carried
  out during the latter half of March 2000. We present preliminary
  results from the observations with the Imaging Vector Magnetograph
  at Mees Solar Observatory. The IVM was operated in a standard mode,
  except that the spectral scan was limited to one point in the core
  of H-alpha and one in the blue wing. This limited spectral sampling,
  together with a recently upgraded data acquisition system, permitted
  a complete measurement of Stokes vectors every 3.5 seconds. The field
  of view was 280 arc sec square, with one arc sec pixels. A second
  camera, exposed simultaneously but with a broad-band filter, provides
  images which allow compensation for relative image motion and stretch
  between exposures. Approximately two dozen flares were observed by
  the IVM during the campaign, including one X-class and one M-class
  flare. We present samples of the observations, including relevant
  spacecraft observations, and discuss the sensitivity of the IVM to
  linear polarization under these conditions. This work was supported
  in part by the SXT project at LMSAL (contract NAS5-38099) and by NASA
  grant NAG5-4941.

---------------------------------------------------------
Title: Electron Trapping and Precipitation in Asymmetric Solar
    Flare Loops
Authors: Aschwanden, M. J.; Fletcher, L.; Sakao, T.; Kosugi, T.;
   Hudson, H.
2000IAUS..195..375A    Altcode:
  Acceleration, propagation, and energy loss of particles energized in
  solar flares cannot be studied separately because their radiative
  signatures observed in the form of hard X-ray bremsstrahlung or
  radio gyrosynchrotron emission represent a convolution of all these
  processes. We analyze hard X-ray emission from solar flares using
  a kinematic model that includes free-streaming electrons (having an
  energy-dependent time-of-flight delay) as well as temporarily trapped
  electrons (which are pitch-angle scattered by Coulomb collisional
  scattering) to determine various physical parameters (trapping times,
  flux asymmetry, loss-cone angles, magnetic mirror ratios) in flare
  loops with asymmetric magnetic fields.

---------------------------------------------------------
Title: Electron Kinematics near the Loss-Cone
Authors: Fletcher, L.; Aschwanden, M. J.
2000SPD....31.0247F    Altcode: 2000BAAS...32..819F
  With the upcoming launch of the HESSI satellite, we expect that
  problems of non-thermal electron transport and radiation signatures
  will once more be the subject of some attention, since this is an
  integral part of the calculation of the spectral and spatial behavior
  of the radiative signatures which will be observed by HESSI. Problems
  of particle transport in coronal magnetic traps are often treated by
  making simple geometrical and timescale arguments for the fractions of
  accelerated particles which are trapped and precipitate from coronal
  loops. Such arguments are used to calculate the populations of,
  for example, directly precipitating and trap-precipitating particles
  (which can in principle be identified from hard X-ray time-series),
  or coronal versus footpoint emission ratios (which can be studied from
  spatially resolved HXR data). Using numerical simulation and analytic
  arguments we have studied the dynamics of particles within coronal
  traps, paying particular attention to the behavior in the vicinity
  of the loss-cone. We find that over a broad range of normally-assumed
  coronal parameters, such as mirror-ratio, loop length and loop density,
  (a) electrons cannot pass easily from the trap region to the loss-cone,
  so that (b) there is no collisionless trap-precipitating component and
  (c) a large fraction of accelerated particles will lose their entire
  energy budget within the coronal loop. We discuss what this means
  for our current understanding of the solar flare environment and our
  interpretation of radiative signatures. This work was supported by
  the Yohkoh/SXT project at LMSAL (NASA grant NAS8-40801) and by the
  U.K. Particle Physics and Astronomy Research Council.

---------------------------------------------------------
Title: Dynamics in Restructuring Active Regions Observed During
    Soho/Yohkoh/Gbo Campaigns
Authors: Schmieder, B.; Deng, Y.; Mandrini, C. H.; Rudawy, P.; Nitta,
   N.; Mason, H.; Fletcher, L.; Martens, P.; Brynildsen, N.
2000AdSpR..25.1879S    Altcode:
  JOP17 and JOP 33 are SOHO Joint Observing Programs in collaboration
  with Yohkoh/SXT and ground based observatories (GBO's), dedicated to
  observe dynamical events through the atmosphere. During runs of these
  programs we observed in restructuring active regions (ARs), surges,
  subflares, bright knots, but not large flares and jets. From these
  observations we have been able to derive some of the responses of the
  coronal and chromospheric plasma to the evolution of the photospheric
  magnetic field. Emerging flux in an AR led to the formation of Arch
  Filament Systems in the chromosphere, hot loops and knots in the
  transition region, and X-ray loops. Frequent surges have been observed
  in relation to parasitic or mixed polarities, but coronal jets have not
  yet been found. We discuss the possible mechanisms acting during the
  restructuring of the active regions (reconnection or “sea-serpent”
  geometries)

---------------------------------------------------------
Title: High-resolution Observations of Plasma Jets in the Solar Corona
Authors: Alexander, David; Fletcher, Lyndsay
1999SoPh..190..167A    Altcode:
  We present recent observations of coronal jets, made by TRACE and
  Yohkoh/SXT on 28 May and 19 August 1998. The high spatial resolution
  of TRACE enables us to see in detail the process of material ejection;
  in the line of Fe ix (one million degrees) we see both bright emitting
  material and dark absorbing/scattering material being ejected, i.e.,
  both hot and cold material, highly collimated and apparently ejected
  along the direction of the overlying field lines. Bright ejecta are
  seen simultaneously in Lyman α for one event and Yohkoh/SXT in the
  other. The jets on the two days are different in that the 19 August
  jet displays the morphology typical of a one-sided anemone jet while
  the 28 May jet exhibits a two-sided jet morphology. The 19 August jet
  shows evidence for rotation and an interesting bifurcation at large
  distances from the energy release site. We study the physical properties
  and energetics of these jetting events, and conclude that existing
  theoretical models capture the essential physics of the jet phenomena.

---------------------------------------------------------
Title: Looptop Hard X-ray Sources
Authors: Fletcher, L.
1999ESASP.448..693F    Altcode: 1999mfsp.conf..693F; 1999ESPM....9..693F
  No abstract at ADS

---------------------------------------------------------
Title: What is Moss?
Authors: Berger, T. E.; De Pontieu, B.; Fletcher, L.; Schrijver,
   C. J.; Tarbell, T. D.; Title, A. M.
1999SoPh..190..409B    Altcode:
  TRACE observations of active regions show a peculiar extreme ultraviolet
  (EUV) emission over certain plage areas. Termed `moss' for its spongy,
  low-lying, appearance, observations and modeling imply that the
  phenomenon is caused by thermal conduction from 3-5 MKcoronal loops
  overlying the plage: moss is the upper transition region emission of
  hot coronal loops. The spongy appearance is due to the presence of
  chromospheric jets or `spicules' interspersed with the EUV emission
  elements. High cadence TRACE observations show that the moss EUV
  elements interact with the chromospheric jets on 10 s time scales. The
  location of EUV emission in the moss does not correlate well to the
  locations of underlying magnetic elements in the chromosphere and
  photosphere, implying a complex magnetic topology for coronal loop
  footpoint regions. We summarize here the key observations leading to
  these conclusions and discuss new implications for understanding the
  structuring of the outer solar atmosphere.

---------------------------------------------------------
Title: Plasma Diagnostics of Transition Region “Moss” using SOHO/CDS
    and TRACE
Authors: Fletcher, Lyndsay; De Pontieu, Bart
1999ApJ...520L.135F    Altcode:
  Recent observations of solar active regions with the Transition Region
  and Coronal Explorer (TRACE) have revealed finely textured, low-lying
  EUV emission, called the “moss,” appearing as a bright dynamic
  pattern with dark inclusions. The moss has been interpreted as the
  upper transition region by Berger and coworkers. In this study we use
  SOHO Coronal Diagnostic Spectrometer and TRACE observations of Active
  Region 8227 on 1998 May 30 to determine the physical parameters of the
  moss material. We establish that the plasma responsible for the moss
  emission has a temperature range of (0.6-1.5)×10<SUP>6</SUP> K and
  is associated with hot loops (T&gt;2×10<SUP>6</SUP> K). Moss plasma
  has an electron density of (2-5)×10<SUP>9</SUP> cm<SUP>-3</SUP> at a
  temperature of 1.3×10<SUP>6</SUP> K, giving a pressure of 0.7-1.7 dynes
  cm<SUP>-2</SUP> (a few times higher than in coronal loops observed in
  the TRACE Fe IX/X λ171 passband). The volume filling factor of the
  moss plasma is of order 0.1, and the path along which the emission
  originates is of order 1000 km long.

---------------------------------------------------------
Title: Coronal Loop Oscillations Observed with the Transition Region
    and Coronal Explorer
Authors: Aschwanden, Markus J.; Fletcher, Lyndsay; Schrijver, Carolus
   J.; Alexander, David
1999ApJ...520..880A    Altcode:
  We report here, for the first time, on spatial oscillations of coronal
  loops, which were detected in extreme-ultraviolet wavelengths (171 Å)
  with the Transition Region and Coronal Explorer, in the temperature
  range of T<SUB>e</SUB>~1.0-1.5 MK. The observed loop oscillations
  occurred during a flare that began at 1998 July 14, 12:55 UT and are
  most prominent during the first 20 minutes. The oscillating loops
  connect the penumbra of the leading sunspot to the flare site in
  the trailing portion. We identified five oscillating loops with an
  average length of L=130,000+/-30,000 km. The transverse amplitude
  of the oscillations is A=4100+/-1300 km, and the mean period
  is T=280+/-30 s. The oscillation mode appears to be a standing
  wave mode (with fixed nodes at the footpoints). We investigate
  different MHD wave modes and find that the fast kink mode with a
  period τ=205(L/10<SUP>10</SUP> cm)(n<SUB>e</SUB>/10<SUP>9</SUP>
  cm<SUP>-3</SUP>)<SUP>1/2</SUP>(B/10 G)<SUP>-1</SUP> s provides the
  best agreement with the observed period. We propose that the onset
  of loop oscillations in distant locations is triggered by a signal or
  disturbance that propagates from the central flare site with a radial
  speed of ~700 km s<SUP>-1</SUP>. Because the observed loop oscillation
  periods are comparable to photospheric 5 minute oscillations, a resonant
  coupling between the two systems is possible. We further find evidence
  for global extreme-UV dimming in the entire active region possibly
  associated with a coronal mass ejection.

---------------------------------------------------------
Title: A new view of the solar outer atmosphere by the Transition
    Region and Coronal Explorer
Authors: Schrijver, C. J.; Title, A. M.; Berger, T. E.; Fletcher, L.;
   Hurlburt, N. E.; Nightingale, R. W.; Shine, R. A.; Tarbell, T. D.;
   Wolfson, J.; Golub, L.; Bookbinder, J. A.; DeLuca, E. E.; McMullen,
   R. A.; Warren, H. P.; Kankelborg, C. C.; Handy, B. N.; De Pontieu, B.
1999SoPh..187..261S    Altcode:
  The Transition Region and Coronal Explorer (TRACE) - described in the
  companion paper by Handy et al. (1999) - provides an unprecedented
  view of the solar outer atmosphere. In this overview, we discuss the
  initial impressions gained from, and interpretations of, the first
  million images taken with TRACE. We address, among other topics,
  the fine structure of the corona, the larger-scale thermal trends,
  the evolution of the corona over quiet and active regions, the high
  incidence of chromospheric material dynamically embedded in the coronal
  environment, the dynamics and structure of the conductively dominated
  transition region between chromosphere and corona, loop oscillations
  and flows, and sunspot coronal loops. With TRACE we observe a corona
  that is extremely dynamic and full of flows and wave phenomena, in
  which loops evolve rapidly in temperature, with associated changes in
  density. This dynamic nature points to a high degree of spatio-temporal
  variability even under conditions that traditionally have been referred
  to as quiescent. This variability requires that coronal heating can
  turn on and off on a time scale of minutes or less along field-line
  bundles with cross sections at or below the instrumental resolution
  of 700 km. Loops seen at 171 Å (∼1 MK) appear to meander through
  the coronal volume, but it is unclear whether this is caused by the
  evolution of the field or by the weaving of the heating through the
  coronal volume, shifting around for periods of up to a few tens of
  minutes and lighting up subsequent field lines. We discuss evidence
  that the heating occurs predominantly within the first 10 to 20 Mm
  from the loop footpoints. This causes the inner parts of active-region
  coronae to have a higher average temperature than the outer domains.

---------------------------------------------------------
Title: Deconvolution of Directly Precipitating and Trap-precipitating
    Electrons in Solar Flare Hard X-Rays. III.Yohkoh Hard X-Ray Telescope
    Data Analysis
Authors: Aschwanden, Markus J.; Fletcher, Lyndsay; Sakao, Taro;
   Kosugi, Takeo; Hudson, Hugh
1999ApJ...517..977A    Altcode:
  We analyze the footpoint separation d and flux asymmetry A of
  magnetically conjugate double footpoint sources in hard X-ray images
  from the Yohkoh Hard X-Ray Telescope (HXT). The data set of 54 solar
  flares includes all events simultaneously observed with the Compton
  Gamma Ray Observatory (CGRO) in high time resolution mode. From the CGRO
  data we deconvolved the direct-precipitation and trap-precipitation
  components previously (in Paper II). Using the combined measurements
  from CGRO and HXT, we develop an asymmetric trap model that allows
  us to quantify the relative fractions of four different electron
  components, i.e., the ratios of direct-precipitating (q<SUB>P1</SUB>,
  q<SUB>P2</SUB>) and trap-precipitating electrons (q<SUB>T1</SUB>,
  q<SUB>T2</SUB>) at both magnetically conjugate footpoints. We find mean
  ratios of q<SUB>P1</SUB>=0.14+/-0.06, q<SUB>P2</SUB>=0.26+/-0.10,
  and q<SUB>T</SUB>=q<SUB>T1</SUB>+q<SUB>T2</SUB>=0.60+/-0.13. We
  assume an isotropic pitch-angle distribution at the
  acceleration site and double-sided trap precipitation
  (q<SUB>T2</SUB>/q<SUB>T1</SUB>=q<SUB>P2</SUB>/q<SUB>P1</SUB>)
  to determine the conjugate loss-cone angles
  (α<SUB>1</SUB>=42<SUP>deg</SUP>+/-11<SUP>deg</SUP> and
  α<SUB>2</SUB>=52<SUP>deg</SUP>+/-10<SUP>deg</SUP>) and magnetic
  mirror ratiosat both footpoints (R<SUB>1</SUB>=1.6,...,4.0 and
  R<SUB>2</SUB>=1.3,...,2.5). From the relative displacement of
  footpoint sources we also measure altitude differences of hard
  X-ray emission at different energies, which are found to decrease
  systematically with higher energies, with a statistical height
  difference of h<SUB>Lo</SUB>-h<SUB>M1</SUB>=980+/-250 km and
  h<SUB>M1</SUB>-h<SUB>M2</SUB>=310+/-300 km between the three lower
  HXT energy channels (Lo, M1, M2).

---------------------------------------------------------
Title: Plasma Diagnostics of Transition Region “Moss” using SOHO/CDS
    and TRACE
Authors: Fletcher, L.; de Pontieu, B.
1999AAS...194.7902F    Altcode: 1999BAAS...31..963F
  Recent observations of solar active regions with the Transition
  Region And Coronal Explorer (TRACE) have revealed finely textured,
  low-lying extreme ultraviolet (EUV) emission, called the “moss”,
  appearing as a bright dynamic pattern with dark inclusions. The moss
  has been interpreted as the upper transition region by Berger et al.,
  (1999). In this study we use simultaneous SOHO Coronal Diagnostic
  Spectrometer (CDS) and TRACE observations of Active Region (AR)
  8227 on 30-May-1998 to determine the physical parameters of the moss
  material. A differential emission measure (DEM) analysis and other
  diagnostic tools establish that the plasma responsible for the moss
  emission has a temperature range of 0.6-1.5 * 10(6) K and is associated
  with hot loops (T &gt; 2 * 10(6) K) observed with CDS. This plasma
  has an electron density of 2-5* 10(9) cm(-3) at a temperature of 1.3 *
  10(6) K, giving a pressure of 0.7-1.7 dyne cm(-2) . Both the density
  and pressure in the moss plasma are a few times higher than in coronal
  loops observed in the TRACE Fe IX/X 171 Angstroms passband. The volume
  filling factor of the moss plasma is of the order 0.1 and the path
  along which the emission originates is of the order 1,000 km long.

---------------------------------------------------------
Title: Dynamics and Plasma Diagnostics of Transition Region “Moss”
    using SOHO/CDS, TRACE and SVST (La Palma)
Authors: de Pontieu, B.; Berger, T. E.; Fletcher, L.; Schrijver,
   C. J.; Title, A. M.
1999AAS...194.7804D    Altcode: 1999BAAS...31..961D
  Recent observations of solar active regions with the Transition
  Region And Coronal Explorer (TRACE) have revealed finely textured,
  low-lying extreme ultraviolet (EUV) emission, called the “moss”,
  appearing as a bright dynamic pattern with dark inclusions. The moss
  has been interpreted as the upper transition region by Berger et al.,
  (1999). In this poster we study the physical conditions in the moss
  plasma, as well as its dynamics and connections to photosphere and
  chromosphere. Using simultaneous SOHO Coronal Diagnostic Spectrometer
  (CDS) and TRACE observations of Active Region (AR) 8227 on 30-May-1998
  we determine the physical parameters of the moss material. We find T_e =
  0.6-1.5 10(6) K and n_e = 2-5 10(9) cm(-3) at a temperature of 1.3 10(6)
  K. The pressure in the moss plasma is higher than that in coronal loops
  observed in the TRACE Fe IX/X 171 Angstroms passband, and moss emission
  is associated with high temperature loops, observed by SXT and by CDS
  in lines of T_max &gt; 2.5 10(6) K. The volume filling factor of the
  moss plasma is of the order 0.1 and the path along which the emission
  originates is of the order 1,000 km long. We examine the dynamics of
  the moss plasma, by making comparisons of TRACE 171 Angstroms movies
  with SVST (La Palma) Ca II K-line, Hα , and G-band movies. Local
  Correlation Tracking (LCT) flowmapping techniques are used to establish
  the photospheric flowfield in plage regions with and without associated
  moss. The relation of moss emission to chromospheric spicules or fibrils
  is examined in detail using Hα movies and dopplergrams. In addition,
  several miniflare events occuring in plage regions are analyzed using
  TRACE and SVST movies. This research was supported by NASA contract
  NAS5-38099 (TRACE) and NASA SR&amp;T grant NASW-98008.

---------------------------------------------------------
Title: Rendering Three-Dimensional Solar Coronal Structures of Active
    Region 8227
Authors: Gary, G. A.; Alexander, D.; Fletcher, L.
1999AAS...194.7807G    Altcode: 1999BAAS...31..962G
  Coronal X-ray and EUV synthesized images of Active Region 8227
  (May-June 1996) are constructed and compared with TRACE, Yohkoh/SXT, and
  SOHO/EIT observations. Using the rendering technique of Gary (1997) and
  Alexander, Gary, and Thompson (1998), specific geometric and physical
  models are used to integrate the plasma emission along the line of sight
  to obtain a rendered image. The instrumental profiles are convolved
  in the integration process as well as unique heating functions. We
  analyze coronal X-ray and EUV structures via the constructing of
  synthesized images and investigate how different heating rates within
  the active region loop system affect the emission characteristics. The
  intercomparison of the emission seen in different telescopes with
  that predicted by the assumed model provides a diagnostic tool for
  determining the properties of the heating and a physical explanation for
  the observed distributions. Of particular note is the presence of bright
  EUV emission at the base of hot X-ray loops, reminiscent of the "moss"
  observed by Berger &amp; et al. (1999), and Fletcher &amp; De Pontieu
  (1999). Gary, G. A.: 1997, Solar Physics, 174, 241. Alexander, D.,
  Gary, G. A., and Thompson, B.J.: 1998, Proc. 2nd ASPE, PASP Conference
  Series. Berger, T. E., De Pontieu, B., Schrijver, C. J., Title, A. M.,
  1999. ApJ Letts. (submitted) Fletcher, L., De Pontieu, B. 1999, ApJ
  Letts. (submitted)

---------------------------------------------------------
Title: Calentamiento de arcos coronales en una región activa por
    reconfiguración topológica del campo magnético.
Authors: López Fuentes, M.; Mandrini, C. H.; Démoulin, P.; Schmieder,
   B.; Fletcher, L.; Mason, H.
1999BAAA...43...24L    Altcode:
  We study the active region (AR) 8048 observed on June 1997 in several
  wavelenghts. The combined observations obtained using CDS (SOHO)
  and SXT (Yohkoh) show the heating of the coronal magnetic loops at
  different atmospheric altitudes. Extrapolating the magnetic field in the
  corona from longitudinal magnetograms from MDI (SOHO), we determine the
  location of Bald Patches in the surroundings of the leading spot. This
  magnetic feature, the emergence of parasitic magnetic polarities and
  the observed photospheric motions provide the conditions to explain
  the observed heating.

---------------------------------------------------------
Title: Generation of solar Hα impact polarization by fragmented
    evaporative upflows
Authors: Fletcher, L.; Brown, J. C.
1998A&A...338..737F    Altcode:
  In this paper a novel mechanism is proposed for the generation of Hα
  impact polarization observed during some solar flares. Rather than
  being generated by the primary particle beams transporting energy from
  the chromosphere to the corona, we suggest that following heating,
  the solar chromosphere evaporates in a fragmented manner, and that
  impact excitations in the regions of interaction of hot evaporating
  and cool non-evaporating material locally generates impact-polarized
  Hα emission. This thermal upflow model is more consistent with
  the large areas and times over which polarization is observed than
  are beam models. A simple model for the process is given, and the
  resulting polarization is calculated and compared with observations,
  under two assumptions about the number density of neutral particles
  in the interaction regions.

---------------------------------------------------------
Title: A Model for Hard X-Ray Emission from the Top of Flaring Loops
Authors: Fletcher, L.; Martens, P. C. H.
1998ApJ...505..418F    Altcode:
  The frequent occurrence of hard X-ray emission from the top of
  flaring loops was one of the discoveries by the Hard X-Ray Telescope
  on board the Japanese Yohkoh satellite. In this paper we take a flare
  current-sheet geometry and show how the combined effect of magnetic
  field convergence and pitch-angle scattering of nonthermal electrons
  injected at the top of the loop results in the generation of a looptop
  source with properties akin to those observed by Yohkoh. We demonstrate
  that a looptop source can be produced in both impulsive and gradual
  phase loops. We further present a possible mechanism for the generation
  of high-temperature “ridges” in the loop legs.

---------------------------------------------------------
Title: A Possible Third Festoon Flow in Atalanta Planitia, Venus
Authors: Fletcher, L.; Wright, H.; Grosfils, E.; Reinen, L.; Gilmore,
   M.; Kozak, S.
1998LPI....29.1188F    Altcode:
  No abstract at ADS

---------------------------------------------------------
Title: Hard X-Ray Emission from a Mirror Trap at the Top of
    Reconnecting Loops
Authors: Martens, P. C. H.; Fletcher, L.
1998ASSL..229..269M    Altcode: 1998opaf.conf..269M
  No abstract at ADS

---------------------------------------------------------
Title: Surges and filaments in active regions during SOHO campaigns
Authors: Schmieder, B.; Deng, Y.; Rudawy, P.; Nitta, N.; Mandrini,
   C. H.; Fletcher, L.; Martens, P.; Innes, D.; Young, P.; Mason, H.
1998ESASP.421..323S    Altcode: 1998sjcp.conf..323S
  No abstract at ADS

---------------------------------------------------------
Title: SOHO: een zonne-observatorium in de ruimte.
Authors: Fletcher, L.
1998Zenit..25....4F    Altcode:
  No abstract at ADS

---------------------------------------------------------
Title: Numerical simulations of coronal particle trapping.
Authors: Fletcher, L.
1997A&A...326.1259F    Altcode:
  In this paper the trapping of high energy particles in solar coronal
  loops is addressed. Using simulations, the time evolution of electrons
  and protons trapped in a magnetic bottle is calculated under various
  scattering conditions and the results compared with loss-cone
  analysis. Thereafter the case of time-dependent injection into a
  magnetic loop is addressed, and the results compared with previous
  analytic work on X and γ-ray delay times.

---------------------------------------------------------
Title: Magnetic pumping in the cataclysmic variable AE Aquarii.
Authors: Kuijpers, J.; Fletcher, L.; Abada-Simon, M.; Horne, K. D.;
   Raadu, M. A.; Ramsay, G.; Steeghs, D.
1997A&A...322..242K    Altcode:
  We propose that the radio outbursts of the cataclysmic variable
  AE Aqr are caused by eruptions of bubbles of fast particles from
  a magnetosphere surrounding the white dwarf. We investigate the
  acceleration process of magnetic pumping in the magnetosphere which
  is periodically driven both by the relative motion with the companion
  and with the infalling spray of gas at the spin frequency of the white
  dwarf. As the accretion rate is relatively low, the conversion of spin
  energy into acceleration (rather than heating) of electrons and protons
  can be efficient. The accelerated particles are trapped in the white
  dwarf magnetosphere until their total energy content becomes comparable
  to that of the trapping magnetic field structure and a MHD instability
  sets in. Synchrotron radiation is emitted in the expelled expanding
  plasmoid at radio and down to millimetric wavelengths. We find that
  there is sufficient energy transferred from the rotation energy of the
  rapidly-spinning white dwarf to fast particles by magnetic pumping to
  explain quiescent and flaring radio emissions.

---------------------------------------------------------
Title: Particle Acceleration and Transport in Reconnecting Plasmas
Authors: Fletcher, Lyndsay; Petkaki, Panagiota
1997SoPh..172..267F    Altcode: 1997ESPM....8..267F
  We model the behaviour of particles in and around X-type magnetic
  configurations, a possible solar flare reconnection geometry. Particles
  are accelerated by a time-varying electric field close to the neutral
  point, and followed by integrating the equations of motion. When
  their motion becomes adiabatic a stochastic simulation is used to
  model their further transport in a collisional magnetised medium.

---------------------------------------------------------
Title: O^{5+} Acceleration by Turbulence in Polar Coronal Holes
Authors: Fletcher, L.; Huber, M. C. E.
1997ESASP.404..379F    Altcode: 1997cswn.conf..379F
  No abstract at ADS

---------------------------------------------------------
Title: Are Coronal Mass Ejections Caused by Magnetic Pumping?
Authors: Kuijpers, Jan; Fletcher, Lyndsay
1996SoPh..169..415K    Altcode:
  Magnetic pumping in the solar corona is revisited. We derive conditions
  under which magnetic pumping can be the cause of heating of loops
  rather than of particle acceleration. Candidate sources for such a
  process are coronal mass ejections (CMEs). Large loops are susceptible
  to heating primarily of protons by magnetic compressions with periods
  between 50 and 5000 s, the observed spectrum of the photospheric
  driver. Efficient heating by pumping occurs since in these large loops
  the density is low enough that the proton-proton collision time is
  comparable to the periods of the external compressions. We suggest
  that CMEs may be pressure-driven explosions of large-beta loops
  caused by magnetic pumping, in contrast to current-driven `flares'
  in low-beta environments.

---------------------------------------------------------
Title: The height distribution of non-thermal X-ray sources in
    impulsive solar flares.
Authors: Fletcher, L.
1996A&A...310..661F    Altcode:
  In this paper we use numerical simulations to accurately model the
  evolution of non-thermal electron distributions in coronal loops,
  from which we calculate electron bremsstrahlung height versus energy
  distributions. The results are compared with results of the Yohkoh
  satellite and it is found that a model taking into account the full
  complexity of electron transport can explain what is observed,
  for quite reasonable loop parameters. We test three loop models,
  the first with no field convergence, the second with field convergence
  occurring rapidly and only in the chromosphere and the third where field
  convergence occurs slowly in the corona. We demonstrate the effects
  of varying parameters of the loop (such as density, length and field
  strength), and of the beam (spectral index, pitch angle distribution)
  and outline parameter regimes in which best agreement with the data can
  be found. Broadly, densities between 2x10^10^ and 3x10^11^cm^-3^ and
  coronal half-lengths L=~1.3-2.7x10^9^cm give qualitatively acceptable
  results. Finally we discuss possible tests to distinguish between the
  various models which can explain the height distribution.

---------------------------------------------------------
Title: Triggering the radio emission from AE Aqr:
Authors: Steeghs, D.; Kuijpers, J.; Fletcher, L.; et al.
1996ASSL..208..167S    Altcode: 1996IAUCo.158..167S; 1996cvro.coll..167S
  No abstract at ADS

---------------------------------------------------------
Title: On Determining Flare Beam Parameters from Loop-top Hard
    X-ray Sources
Authors: Fletcher, L.
1996ApL&C..34..151F    Altcode:
  No abstract at ADS

---------------------------------------------------------
Title: Radio Emission from AE Aquarii
Authors: Abada-Simon, M.; Bastian, T. S.; Fletcher, L.; Horne, K.;
   Kuijpers, J.; Steeghs, D.; Bookbinder, J. A.
1996ASPC...93..182A    Altcode: 1996ress.conf..182A
  No abstract at ADS

---------------------------------------------------------
Title: The Height Distribution of Hard X-rays in Impulsive Solar
    Flares
Authors: Fletcher, L.
1996mpsa.conf..549F    Altcode: 1996IAUCo.153..549F
  No abstract at ADS

---------------------------------------------------------
Title: On the generation of loop-top impulsive hard X-ray sources.
Authors: Fletcher, L.
1995A&A...303L...9F    Altcode:
  Recently observed with the Hard X-ray Telescope onboard Yohkoh,
  loop-top hard X-ray sources have focussed interest on energy release
  in solar flares. Possibly a direct indication of the site of particle
  acceleration, they have thus far only been interpreted as thermal
  sources. In this letter we propose instead that the sources arise as
  a result of transport effects, and show using a stochastic simulation
  of non-thermal electron transport in a simple loop model, that many
  characteristics of the loop-top source can be reproduced.

---------------------------------------------------------
Title: Solar flare Hα impact polarization from high energy electrons?
Authors: Fletcher, L.; Brown, J. C.
1995A&A...294..260F    Altcode:
  In this paper we investigate the possibility of obtaining Hα line
  linear polarization in solar flares following the excitation of
  neutral hydrogen by energetic electron beams with a large initial
  pitch angle. We compare the factors affecting the sign, magnitude and
  intensity of polarized radiation collisionally excited by electron
  and proton beams and present a calculation of the polarization which
  could be observed from an electron beam, using a stochastic simulation
  to solve the Fokker-Planck evolution equation for the electron beam in
  the collisionally thick chromosphere, in the presence of a converging
  magnetic field. We find that polarization from electron beams is
  possible but requires extreme energy fluxes which are unlikely to be
  present for any length of time during solar flares.

---------------------------------------------------------
Title: Modelling particle transport with stochastic simulations
Authors: Fletcher, Lyndsay
1994SSRv...68..239F    Altcode:
  We use stochastic simulations to calculate the evolution of particle
  distributions in complex situations. Comparison of numerical and
  analytical solutions is made, for the case of electrons moving from
  the corona to the chromosphere and undergoing pure scattering. A
  temporally fragmented beam injection is treated, under various
  atmospheric conditions.

---------------------------------------------------------
Title: Foreword
Authors: van den Oord, Bert; Kuijpers, Jan; Kuperus, Max; Benz, A. O.;
   Brown, J. C.; Einaudi, G.; Kuperus, M.; Raadu, M. A.; Trottet, G.;
   van den Oord, G. H. J.; Vlahos, L.; Zheleznyakov, V. V.; Wijburg,
   Marion; Fletcher, Lyndsay; Volwerk, Martin
1994SSRv...68D..17V    Altcode:
  No abstract at ADS

---------------------------------------------------------
Title: Hα impact polarization as a solar and astrophysical particle
    diagnostic
Authors: Fletcher, Lyndsay
1993PhDT.......113F    Altcode:
  No abstract at ADS

---------------------------------------------------------
Title: H-alpha polarization of wind-heated optical bullets in SS 433.
Authors: Brown, J. C.; Fletcher, L.
1992A&A...259L..43B    Altcode:
  Mechanisms for energy supply to the optical bullets are discussed. It is
  pointed out that in the case of heating by bullet collisions with the
  system wind, recently shown to be a likely heating candidate, impact
  polarization of the H-alpha line should be generated. An estimate
  shows that this line polarization should be at least 0.2 percent and
  orthogonal to the jet, precessing with it on the sky. This should be
  observable and is proposed as a diagnostic of the wind heating model,
  in contrast to turbulent internal heating.

---------------------------------------------------------
Title: Asymmetric Flux Loops in Active Regions - Part Two
Authors: Petrovay, K.; Brown, J. C.; van Driel-Gesztelyi, L.; Fletcher,
   L.; Marik, M.; Stewart, G.
1990SoPh..127...51P    Altcode:
  We propose that magnetic flux loops in the subphotospheric layers
  of the Sun are seriously asymmetrical as a consequence of the drag
  force exerted on them because of the different rotational rate of the
  surrounding plasma. In numerical models of stationary slender flux
  loops in the plane parallel approximation we show that a serious
  tilt is both possible and probable. Observational facts (see van
  Driel-Gesztelyi and Petrovay, 1989; Paper I) strongly support the case
  for high asymmetry. The different stability of p and f spots may also
  be related to such an asymmetry.

---------------------------------------------------------
Title: Aerodynamic heating and thermal protection systems
Authors: Fletcher, L. S.
1978PrAA...59.....F    Altcode:
  The aerothermal environment is considered, taking into account
  the aerothermal environment for the Pioneer Venus multiprobe
  mission, shuttle elevon cove aerodynamic heating by ingested flow,
  aerothermodynamic base heating, vortices induced in a stagnation region
  by wakes, three-dimensional shock-wave interference heating prediction,
  methods for predicting radiation-coupled flowfields about planetary
  entry probes, shock-tube studies of silicon-compound vapors, and Mach
  number and wall temperature effects on turbulent heat blockage. A
  comparison of calculated and measured rocket plume infrared radiation
  is discussed along with a band model for calculating radiance and
  transmission of water vapor and carbon dioxide, and a comparison
  of theoretical and experimental infrared radiation from a rocket
  exhaust. Thermal protection systems are examined and attention
  is given to the effect of melt removal by aerodynamic shear on
  melt-through of metal plates, the ablation performance of tungsten
  and copper-infiltrated tungsten systems in arc jets, the asymmetric
  nose-tip shape change during atmospheric entry, the high-pressure arc
  test performance of carbon-carbon nose tips, and segmented tungsten
  nose tips for high-performance flight vehicles. Individual items were
  announced in issues 07, 08, 17, and 18, 1977.

---------------------------------------------------------
Title: A Search for a Buried Meteorite
Authors: Fletcher, L.
1906Natur..74..490F    Altcode:
  No abstract at ADS

---------------------------------------------------------
Title: L'Uranolithe de Crumlin
Authors: Fletcher, L.
1903BSAFR..17..142F    Altcode:
  No abstract at ADS

---------------------------------------------------------
Title: Fall of a Meteoric Stone near Crumlin (Co. Antrim) September 13
Authors: Fletcher, L.
1902Natur..66..577F    Altcode:
  No abstract at ADS

---------------------------------------------------------
Title: The Supposed Occurrence of Widespread Meteoritic Showers
Authors: Fletcher, L.
1891Natur..43R.295F    Altcode:
  No abstract at ADS