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

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Title: Quantifying Properties of Photospheric Magnetic Cancellations
    in the Quiet Sun Internetwork
Authors: Ledvina, Vincent E.; Kazachenko, Maria D.; Criscuoli, Serena;
   Tilipman, Dennis; Ermolli, Ilaria; Falco, Mariachiara; Guglielmino,
   Salvatore; Jafarzadeh, Shahin; van der Voort, Luc Rouppe; Zuccarello,
   Francesca
2022ApJ...934...38L    Altcode: 2022arXiv220604644L
  We analyzed spectropolarimetric data from the Swedish 1 m Solar
  Telescope to investigate the physical properties of small-scale magnetic
  cancellations in the quiet Sun photosphere. Specifically, we looked at
  the full Stokes polarization profiles along the Fe I 557.6 nm and of the
  Fe I 630.1 nm lines measured by the CRisp Imaging SpectroPolarimeter to
  study the temporal evolution of the line-of-sight magnetic field during
  42.5 minutes of quiet Sun evolution. From this magnetogram sequence, we
  visually identified 38 cancellation events. We then used the Yet Another
  Feature Tracking Algorithm to characterize the physical properties of
  these magnetic cancellations. We found on average 1.6 × 10<SUP>16</SUP>
  Mx of magnetic flux canceled in each event with an average cancellation
  rate of 3.8 × 10<SUP>14</SUP> Mx s<SUP>-1</SUP>. The derived canceled
  flux is associated with strong downflows, with an average speed of V
  <SUB>LOS</SUB> ≍ 1.1 km s<SUP>-1</SUP>. Our results show that the
  average lifetime of each event is 9.2 minutes with an average of 44.8%
  of initial magnetic flux being canceled. Our estimates of magnetic
  fluxes provide a lower limit since studied magnetic cancellation events
  have magnetic field values that are very close to the instrument noise
  level. We observed no horizontal magnetic fields at the cancellation
  sites and therefore cannot conclude whether the events are associated
  with structures that could cause magnetic reconnection.

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Title: IBIS-A: The IBIS data Archive. High-resolution observations
    of the solar photosphere and chromosphere with contextual data
Authors: Ermolli, Ilaria; Giorgi, Fabrizio; Murabito, Mariarita;
   Stangalini, Marco; Guido, Vincenzo; Molinaro, Marco; Romano, Paolo;
   Guglielmino, Salvatore L.; Viavattene, Giorgio; Cauzzi, Gianna;
   Criscuoli, Serena; Reardon, Kevin P.; Tritschler, Alexandra
2022A&A...661A..74E    Altcode: 2022arXiv220209946E
  Context. The IBIS data Archive (IBIS-A) stores data acquired with
  the Interferometric BIdimensional Spectropolarimeter (IBIS), which
  was operated at the Dunn Solar Telescope of the US National Solar
  Observatory from June 2003 to June 2019. The instrument provided series
  of high-resolution narrowband spectropolarimetric imaging observations
  of the photosphere and chromosphere in the range 5800-8600 Å and
  co-temporal broadband observations in the same spectral range and
  with the same field of view as for the polarimetric data. <BR />
  Aims: We present the data currently stored in IBIS-A, as well as the
  interface utilized to explore such data and facilitate its scientific
  exploitation. To this end, we also describe the use of IBIS-A data
  in recent and undergoing studies relevant to solar physics and
  space weather research. <BR /> Methods: IBIS-A includes raw and
  calibrated observations, as well as science-ready data. The latter
  comprise maps of the circular, linear, and net circular polarization,
  and of the magnetic and velocity fields derived for a significant
  fraction of the series available in the archive. IBIS-A furthermore
  contains links to observations complementary to the IBIS data, such
  as co-temporal high-resolution observations of the solar atmosphere
  available from the instruments onboard the Hinode and IRIS satellites,
  and full-disk multi-band images from INAF solar telescopes. <BR />
  Results: IBIS-A currently consists of 30 TB of data taken with IBIS
  during 28 observing campaigns performed in 2008 and from 2012 to 2019
  on 159 days. Of the observations, 29% are released as Level 1 data
  calibrated for instrumental response and compensated for residual seeing
  degradation, while 10% of the calibrated data are also available as
  Level 1.5 format as multi-dimensional arrays of circular, linear, and
  net circular polarization maps, and line-of-sight velocity patterns;
  81% of the photospheric calibrated series present Level 2 data with
  the view of the magnetic and velocity fields of the targets, as derived
  from data inversion with the Very Fast Inversion of the Stokes Vector
  code. Metadata and movies of each calibrated and science-ready series
  are also available to help users evaluate observing conditions. <BR />
  Conclusions: IBIS-A represents a unique resource for investigating
  the plasma processes in the solar atmosphere and the solar origin of
  space weather events. The archive currently contains 454 different
  series of observations. A recently undertaken effort to preserve
  IBIS observations is expected to lead in the future to an increase in
  the raw measurements and the fraction of processed data available in
  IBIS-A. <P />Research supported by the H2020 SOLARNET grant no. 824135.

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Title: Revisiting the Solar Research Cyberinfrastructure Needs:
    A White Paper of Findings and Recommendations
Authors: Nita, Gelu; Ahmadzadeh, Azim; Criscuoli, Serena;
   Davey, Alisdair; Gary, Dale; Georgoulis, Manolis; Hurlburt, Neal;
   Kitiashvili, Irina; Kempton, Dustin; Kosovichev, Alexander; Martens,
   Piet; McGranaghan, Ryan; Oria, Vincent; Reardon, Kevin; Sadykov,
   Viacheslav; Timmons, Ryan; Wang, Haimin; Wang, Jason T. L.
2022arXiv220309544N    Altcode:
  Solar and Heliosphere physics are areas of remarkable data-driven
  discoveries. Recent advances in high-cadence, high-resolution
  multiwavelength observations, growing amounts of data from realistic
  modeling, and operational needs for uninterrupted science-quality data
  coverage generate the demand for a solar metadata standardization and
  overall healthy data infrastructure. This white paper is prepared as
  an effort of the working group "Uniform Semantics and Syntax of Solar
  Observations and Events" created within the "Towards Integration of
  Heliophysics Data, Modeling, and Analysis Tools" EarthCube Research
  Coordination Network (@HDMIEC RCN), with primary objectives to discuss
  current advances and identify future needs for the solar research
  cyberinfrastructure. The white paper summarizes presentations and
  discussions held during the special working group session at the
  EarthCube Annual Meeting on June 19th, 2020, as well as community
  contribution gathered during a series of preceding workshops and
  subsequent RCN working group sessions. The authors provide examples
  of the current standing of the solar research cyberinfrastructure, and
  describe the problems related to current data handling approaches. The
  list of the top-level recommendations agreed by the authors of the
  current white paper is presented at the beginning of the paper.

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Title: Final Report for SAG 21: The Effect of Stellar Contamination
    on Space-based Transmission Spectroscopy
Authors: Rackham, Benjamin V.; Espinoza, Néstor; Berdyugina, Svetlana
   V.; Korhonen, Heidi; MacDonald, Ryan J.; Montet, Benjamin T.; Morris,
   Brett M.; Oshagh, Mahmoudreza; Shapiro, Alexander I.; Unruh, Yvonne C.;
   Quintana, Elisa V.; Zellem, Robert T.; Apai, Dániel; Barclay, Thomas;
   Barstow, Joanna K.; Bruno, Giovanni; Carone, Ludmila; Casewell, Sarah
   L.; Cegla, Heather M.; Criscuoli, Serena; Fischer, Catherine; Fournier,
   Damien; Giampapa, Mark S.; Giles, Helen; Iyer, Aishwarya; Kopp, Greg;
   Kostogryz, Nadiia M.; Krivova, Natalie; Mallonn, Matthias; McGruder,
   Chima; Molaverdikhani, Karan; Newton, Elisabeth R.; Panja, Mayukh;
   Peacock, Sarah; Reardon, Kevin; Roettenbacher, Rachael M.; Scandariato,
   Gaetano; Solanki, Sami; Stassun, Keivan G.; Steiner, Oskar; Stevenson,
   Kevin B.; Tregloan-Reed, Jeremy; Valio, Adriana; Wedemeyer, Sven;
   Welbanks, Luis; Yu, Jie; Alam, Munazza K.; Davenport, James R. A.;
   Deming, Drake; Dong, Chuanfei; Ducrot, Elsa; Fisher, Chloe; Gilbert,
   Emily; Kostov, Veselin; López-Morales, Mercedes; Line, Mike; Močnik,
   Teo; Mullally, Susan; Paudel, Rishi R.; Ribas, Ignasi; Valenti, Jeff A.
2022arXiv220109905R    Altcode:
  Study Analysis Group 21 (SAG21) of the Exoplanet Exploration Program
  Analysis Group (ExoPAG) was organized to study the effect of stellar
  contamination on space-based transmission spectroscopy, a method for
  studying exoplanetary atmospheres by measuring the wavelength-dependent
  radius of a planet as it transits its star. Transmission spectroscopy
  relies on a precise understanding of the spectrum of the star being
  occulted. However, stars are not homogeneous, constant light sources
  but have temporally evolving photospheres and chromospheres with
  inhomogeneities like spots, faculae, and plages. This SAG has brought
  together an interdisciplinary team of more than 100 scientists, with
  observers and theorists from the heliophysics, stellar astrophysics,
  planetary science, and exoplanetary atmosphere research communities,
  to study the current needs that can be addressed in this context to
  make the most of transit studies from current NASA facilities like
  HST and JWST. The analysis produced 14 findings, which fall into
  three Science Themes encompassing (1) how the Sun is used as our best
  laboratory to calibrate our understanding of stellar heterogeneities
  ("The Sun as the Stellar Benchmark"), (2) how stars other than the Sun
  extend our knowledge of heterogeneities ("Surface Heterogeneities of
  Other Stars") and (3) how to incorporate information gathered for the
  Sun and other stars into transit studies ("Mapping Stellar Knowledge
  to Transit Studies").

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Title: Spectral Runway: An Analysis of Solar Balmer Lines through
    both Observations and Models
Authors: Burnham, Emilie; Criscuoli, Serena; Kowalski, Adam; Harder,
   Jerald; Meisner, Randy
2021AGUFMSH45B2367B    Altcode:
  Spectral analysis provides a glimpse into the physical properties of
  stellar atmospheres, which includes temperature, density, magnetic
  signatures, and so on. Balmer lines specifically are used as proxies
  for atmospheric activity, as they have been used to determine stellar
  effective temperatures, and used to constrain stellar atmospheric
  models. Here, we are interested in the variations of Balmer lines
  induced by stellar surface magnetism, which is known to affect the
  atmospheres of orbiting planets and is a factor in determining
  their habitability. As direct solar measurements and spatially
  resolved stellar spectra are not always available, models are vital
  to the understanding of the magnetic contribution to stellar spectral
  variability. In this context, the Sun offers a unique opportunity for
  direct observations of the effects of magnetic features on spectral
  irradiance and further validation with state-of-the-art models. In this
  study we utilize high spatial resolution spectroscopic observations
  obtained at the Dunn Solar Telescope to investigate how surface
  magnetism affects the shape of Balmer line profiles, specifically
  H-alpha and H-gamma. Observational results are then compared with
  theoretical spectra obtained with the Rybiki and Hummer synthesis
  code using two sets of one-dimensional solar atmospheric models (each
  describing different types of quiet and active regions) published
  in Fontenla et al. 1999 and Fontenla et al. 2011, respectively. At
  this point, it seems that the 2011 models are an overall better
  representation of our quiet sun observations than the 1999 models, for
  the 1999 models have far deeper line profiles than would be expected for
  the quiet sun atmospheric structures that were observed. By determining
  the atmospheric models that best fit the observations, our results
  provide important information for improving the understanding of the
  solar atmosphere and for the modeling of stellar spectral variability
  that would, in turn, impact the search for habitable exoplanets.

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Title: Solar Atmosphere Radiative Transfer Model Comparison based
    on 3D MHD Simulations
Authors: Haberreiter, Margit; Criscuoli, Serena; Rempel, Matthias;
   Mendes Domingos Pereira, Tiago
2021AGUFMSH43A..06H    Altcode:
  The reconstruction of the solar spectral irradiance (SSI) on various
  time scales is essential for the understanding of the Earths climate
  response to the SSI variability. The driver of the SSI variability
  is understood to be the intensity contrast of magnetic features
  present on the Sun with respect to the largely non-magnetic quiet
  Sun. However, different spectral synthesis codes lead to diverging
  projections of SSI variability. We present a study in which we compare
  three different radiative transfer codes and carry out a a detailed
  analysis of their performance. We perform the spectral synthesis at
  the continuum wavelength of 665 nm with the Code for Solar Irradiance
  (COSI), and the Rybicki-Hummer (RH), and Max Planck University of
  Chicago Radiative MHD (MURaM) codes for three 3D MHD simulations
  snapshots, a non-magnetic case, and MHD simulations with 100 G, and 200
  G magnetic field strength. We determine the intensity distributions, the
  intensity differences and ratios for the spectral synthesis codes. We
  identify that the largest discrepancies originate in the intergranular
  lanes where the most field concentration occurs. Overall, the applied
  radiative transfer codes give consistent intensity distributions. Also,
  the intensity variation as a function of magnetic field strength for
  the particular 100 G and 200 G snapshots agree within the 2-3% range.

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Title: Prediction of Sunspot and Plage Coverage for Solar Cycle 25
Authors: Penza, Valentina; Berrilli, Francesco; Bertello, Luca;
   Cantoresi, Matteo; Criscuoli, Serena
2021ApJ...922L..12P    Altcode: 2021arXiv211102928P
  Solar variability occurs over a broad range of spatial and temporal
  scales, from the Sun's brightening over its lifetime to the fluctuations
  commonly associated with magnetic activity over minutes to years. The
  latter activity includes most prominently the 11 yr sunspot solar
  cycle and its modulations. Space weather events, in the form of
  solar flares, solar energetic particles, coronal mass ejections,
  and geomagnetic storms, have long been known to approximately follow
  the solar cycle occurring more frequently at solar maximum than solar
  minimum. These events can significantly impact our advanced technologies
  and critical infrastructures, making the prediction for the strength of
  future solar cycles particularly important. Several methods have been
  proposed to predict the strength of the next solar cycle, cycle 25,
  with results that are generally not always consistent. Most of these
  methods are based on the international sunspot number time series,
  or other indicators of solar activity. We present here a new approach
  that uses more than 100 yr of measured fractional areas of the visible
  solar disk covered by sunspots and plages and an empirical relationship
  for each of these two indices of solar activity in even-odd cycles. We
  anticipate that cycle 25 will peak in 2024 and will last for about 12
  yr, slightly longer than cycle 24. We also found that, in terms of
  sunspot and plage areas coverage, the amplitude of cycle 25 will be
  substantially similar or slightly higher than cycle 24.

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Title: Solar atmosphere radiative transfer model comparison based
    on 3D MHD simulations
Authors: Haberreiter, M.; Criscuoli, S.; Rempel, M.; Pereira, T. M. D.
2021A&A...653A.161H    Altcode: 2021arXiv210902681H
  Context. The reconstruction of the solar spectral irradiance (SSI)
  on various time scales is essential for the understanding of the
  Earth's climate response to the SSI variability. <BR /> Aims: The
  driver of the SSI variability is understood to be the intensity
  contrast of magnetic features present on the Sun with respect to
  the largely non-magnetic quiet Sun. However, different spectral
  synthesis codes lead to diverging projections of SSI variability. In
  this study we compare three different radiative transfer codes and
  carry out a detailed analysis of their performance. <BR /> Methods:
  We perform the spectral synthesis at the continuum wavelength of
  665 nm with the Code for Solar Irradiance, and the Rybicki-Hummer,
  and Max Planck University of Chicago Radiative MHD codes for three 3D
  MHD simulations snapshots, a non-magnetic case, and MHD simulations
  with 100 G, and 200 G magnetic field strength. <BR /> Results: We
  determine the intensity distributions, the intensity differences and
  ratios for the spectral synthesis codes. We identify that the largest
  discrepancies originate in the intergranular lanes where the most
  field concentration occurs. <BR /> Conclusions: Overall, the applied
  radiative transfer codes give consistent intensity distributions. Also,
  the intensity variation as a function of magnetic field strength for
  the particular 100 G and 200 G snapshots agree within the 2-3% range.

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Title: Deep Learning Based Reconstruction of Total Solar Irradiance
Authors: Abduallah, Yasser; Wang, Jason T. L.; Shen, Yucong; Alobaid,
   Khalid A.; Criscuoli, Serena; Wang, Haimin
2021arXiv210711042A    Altcode:
  The Earth's primary source of energy is the radiant energy generated
  by the Sun, which is referred to as solar irradiance, or total solar
  irradiance (TSI) when all of the radiation is measured. A minor
  change in the solar irradiance can have a significant impact on the
  Earth's climate and atmosphere. As a result, studying and measuring
  solar irradiance is crucial in understanding climate changes and solar
  variability. Several methods have been developed to reconstruct total
  solar irradiance for long and short periods of time; however, they
  are physics-based and rely on the availability of data, which does not
  go beyond 9,000 years. In this paper we propose a new method, called
  TSInet, to reconstruct total solar irradiance by deep learning for
  short and long periods of time that span beyond the physical models'
  data availability. On the data that are available, our method agrees
  well with the state-of-the-art physics-based reconstruction models. To
  our knowledge, this is the first time that deep learning has been used
  to reconstruct total solar irradiance for more than 9,000 years.

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Title: Measuring and modeling the variability of solar Balmer lines
Authors: Criscuoli, S.; Marchenko, S.; Deland, M.; Choudhary, D.;
   Kopp, G.
2021AAS...23811312C    Altcode:
  We investigate the variability of solar Balmer lines (H-alpha,
  beta, gamma, delta) observed by space-borne radiometers (SORCE,
  SCIAMACHY, GOME-2, OMI, and TROPOMI), combining these precise,
  long-term observations with abundant, high-resolution data from the
  ground-based NSO/ISS spectrograph. We relate the detected variability
  to the appearance of magnetic features on the solar disk. We find that
  on solar-rotation timescales Balmer line activity indices (defined as
  line-core to line-wing ratios) closely follow variations in the total
  solar irradiance (which is predominantly photospheric), thus frequently
  (specifically, during passages of big sunspot groups) deviates from
  behavior of the line-activity indices that track chromospheric activity
  levels. At longer timescales (years), the correlation with chromospheric
  indices increases, with periods of low- or even anti- correlation found
  at intermediate timescales. Comparisons with Balmer-line variability
  patterns obtained from a semi-empirical model indicate that it is
  unlikely that the periods of low/anti correlations can be ascribed to
  the presence of filaments, in contradiction to some previous studies.

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Title: The National Science Foundation's Daniel K. Inouye Solar
    Telescope — Status Update
Authors: Rimmele, T.; Woeger, F.; Tritschler, A.; Casini, R.; de Wijn,
   A.; Fehlmann, A.; Harrington, D.; Jaeggli, S.; Anan, T.; Beck, C.;
   Cauzzi, G.; Schad, T.; Criscuoli, S.; Davey, A.; Lin, H.; Kuhn, J.;
   Rast, M.; Goode, P.; Knoelker, M.; Rosner, R.; von der Luehe, O.;
   Mathioudakis, M.; Dkist Team
2021AAS...23810601R    Altcode:
  The National Science Foundation's 4m Daniel K. Inouye Solar Telescope
  (DKIST) on Haleakala, Maui is now the largest solar telescope in the
  world. DKIST's superb resolution and polarimetric sensitivity will
  enable astronomers to unravel many of the mysteries the Sun presents,
  including the origin of solar magnetism, the mechanisms of coronal
  heating and drivers of flares and coronal mass ejections. Five
  instruments, four of which provide highly sensitive measurements
  of solar magnetic fields, including the illusive magnetic field of
  the faint solar corona. The DKIST instruments will produce large and
  complex data sets, which will be distributed through the NSO/DKIST Data
  Center. DKIST has achieved first engineering solar light in December
  of 2019. Due to COVID the start of the operations commissioning phase
  is delayed and is now expected for fall of 2021. We present a status
  update for the construction effort and progress with the operations
  commissioning phase.

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Title: Solar Magnetism and Radiation
Authors: Petrie, Gordon; Criscuoli, Serena; Bertello, Luca
2021GMS...258...83P    Altcode:
  No abstract at ADS

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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.

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Title: Understanding variability of solar Balmer lines
Authors: Criscuoli, Serena; Marchenko, Sergey; DeLand, Matthew;
   Choudary, Debi; Kopp, Greg
2021csss.confE.290C    Altcode:
  Precise, adequately high-cadence, long-term records of spectral
  variability at different temporal scales lead to better understanding of
  a wide variety of phenomena including stellar atmospheres and dynamos,
  evolution of the magnetic fields on a stellar photosphere, convective
  motions, and rotational periods. These, in turn, are fundamental
  for the detectability of exoplanets, the characterization of their
  atmospheres and habitability, as well as characterization of stellar
  magnetospheres and winds. The Sun, viewed as a star via spectral
  irradiance measurements, offers a means of exploring such measurements
  while also having the imaging capability to help discern the causes
  of observed spectral variations. In this study, we investigate the
  variability of solar Balmer lines (H-α, β, γ and δ) observed by
  space-borne radiometers, combining these precise, long-term observations
  with abundant, high-resolution data from the ground-based NSO/ISS
  spectrograph. We relate the detected variability to magnetic features
  on the solar disk. We find that on solar-rotation timescales (~month),
  the Balmer line activity indices (defined as line-core to line-wing
  ratios) closely follow variations in the total solar irradiance
  (which is predominantly photospheric), thus frequently (specifically,
  during passages of big sunspot groups) deviates from behavior of the
  line-activity indices that track chromospheric activity levels. At
  longer timescales (years), the correlation with chromospheric indices
  increases, with periods of low- or even anti- correlation found at
  intermediate timescales. Comparisons with Balmer-line variability
  patterns obtained from a semi-empirical model indicate the periods
  of low/anti correlations should be attributed to the increase of the
  relative abundance of network, which affects the Ca-index while leaving
  almost un-altered the Hα-index.

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Title: Solar activity and responses observed in Balmer lines
Authors: Marchenko, S.; Criscuoli, S.; DeLand, M. T.; Choudhary,
   D. P.; Kopp, G.
2021A&A...646A..81M    Altcode:
  Context. Many stars show Sun-like magnetic activity cycles, which
  are frequently observed by tracking changes in the chromospherically
  sensitive CaII H&amp;K doublet. However, relationships between the
  line profile changes related to the magnetic activity seen in strong
  spectral transitions in other portions of a stellar spectrum are
  yet to be understood. <BR /> Aims: We follow variability patterns in
  various solar lines in order to relate them to the emergence, passage,
  and decay of active solar regions. <BR /> Methods: The line activity
  indices (core-to-wing ratio) for the upper Balmer lines - Hβ, Hγ,
  and Hδ - are constructed from the near-daily solar measurements
  acquired by the Ozone Monitoring Instrument and the TROPOspheric
  Monitoring Instrument. <BR /> Results: On solar rotation timescales,
  the upper Balmer line activity indices closely follow variations in
  the total solar irradiance, r ∼ -(0.6 - 0.7), and thus frequently
  deviate from the behavior of the line activity indices that track
  chromospheric activity levels (e.g., the CH 430 nm band used in this
  study), specifically during passages of big sunspot groups.

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Title: Multi-Wavelength Modeling and Analysis of the Center-to-Limb
    Effects of Solar Spectroscopy and Helioseismology
Authors: Kitiashvili, I.; Zhao, J.; Sadykov, V. M.; Criscuoli, S.;
   Kosovichev, A. G.; Wray, A. A.
2020AGUFMSH0020003K    Altcode:
  An accurate interpretation of observed solar dynamics with different
  instruments requires modeling solar magnetoconvection in different
  regimes, as well as taking into account center-to-limb effects,
  magnetic fields, and turbulence. Realistic 3D radiative MHD modeling
  of the solar magnetoconvection and atmosphere allows us to generate
  synthetic observables that directly link the physical properties of
  the solar plasma to spectroscopic and helioseismic observables. In
  this work, we investigate the influence of the center-to-limb effects
  for a wide range of wavelengths, which correspond to the operational
  lines of HMI/SDO, Hinode, DKIST, and other instruments. In particular,
  we discuss the wavelength-dependency of the center-to-limb helioseismic
  observations of acoustic travel times that are used for diagnostics of
  the deep meridional circulation, as well as 'concave' Sun effect. The
  presented study will support interpretation of helioseismic inversion
  results by taking into account realistic coupling of subsurface and
  atmosphere, and geometry-related effects. In particular, it allows us
  to improve accuracy of solar subsurface measurements from the SoHO and
  SDO missions, and resolve the long-standing problem of the meridional
  circulation and evolution with the solar cycle.

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Title: Investigation of the X1.6 Flare Occurred in the Great Active
    Region 12192
Authors: Zuccarello, F.; Guglielmino, S. L.; Ferrente, F.; Criscuoli,
   S.; Romano, P.
2020AGUFMSH0430003Z    Altcode:
  The X1.6 flare observed on 22 October 2014 (SOL2014-10-22T14:28)
  was among the strongest flares occurred in the magnetically complex,
  great active region NOAA 12192. It was a confined flare, without an
  accompanying CME, despite the large amount of released energy. Here,
  we report on full spectro-polarimetric observations acquired by
  the IBIS/DST instrument along the Ca II 8542 line, analyzing the
  polarization signatures during the flare, together with complementary
  data from SDO and IRIS. We attempt to derive new information about
  the chromospheric magnetic field topology, which can help to explain
  the lack of ejecta.

---------------------------------------------------------
Title: Challenges and Advances in Modeling of the Solar Atmosphere:
    A White Paper of Findings and Recommendations
Authors: Criscuoli, Serena; Kazachenko, Maria; Kitashvili, Irina;
   Kosovichev, Alexander; Martínez Pillet, Valentín; Nita, Gelu;
   Sadykov, Viacheslav; Wray, Alan
2021arXiv210100011C    Altcode:
  The next decade will be an exciting period for solar astrophysics, as
  new ground- and space-based instrumentation will provide unprecedented
  observations of the solar atmosphere and heliosphere. The synergy
  between modeling effort and comprehensive analysis of observations
  is crucial for the understanding of the physical processes behind
  the observed phenomena. However, the unprecedented wealth of data on
  one hand, and the complexity of the physical phenomena on the other,
  require the development of new approaches in both data analysis and
  numerical modeling. In this white paper, we summarize recent numerical
  achievements to reproduce structure, dynamics, and observed phenomena
  from the photosphere to the low corona and outline challenges we expect
  to face for the interpretation of future observations.

---------------------------------------------------------
Title: A new spectroscopic method for measuring the temperature
    gradient in the solar photosphere. Generalized application in
    magnetized regions
Authors: Faurobert, M.; Criscuoli, S.; Carbillet, M.; Contursi, G.
2020A&A...642A.186F    Altcode:
  Context. The contribution of quiet-Sun regions to the solar irradiance
  variability is currently unclear. Certain solar-cycle variations of
  the quiet-Sun's physical structure, such as the temperature gradient,
  might affect the irradiance. Accurate measurements of this quantity
  over the course of the activity cycle would improve our understanding
  of long-term irradiance variations. <BR /> Aims: In a previous work,
  we introduced and successfully tested a new spectroscopic method
  for measuring the photospheric temperature gradient directly on a
  geometric scale in the case of non-magnetic regions. In this paper,
  we generalize this method for moderately magnetized regions that
  may be encountered in the quiet solar photosphere. <BR /> Methods:
  To simulate spectroscopic observations, we used synthetic Stokes
  profiles I and V of the magnetic FeI 630.15 nm line and intensity
  profiles of the non-magnetic FeI 709 nm line computed from realistic
  three-dimensional magneto-hydrodynamical simulations of the photospheric
  granulation and line radiative transfer under local thermodynamical
  equilibrium conditions. We then obtained maps at different levels
  in the line-wings by convolution with the instrumental point spread
  function (PSF) under various conditions of atmospheric turbulence -
  with and without correction by an adaptive optics (AO) system. The
  PSF were obtained with the PAOLA software and the AO performance is
  inspired by the system that will be operating on the Daniel K. Inouye
  Solar Telescope. <BR /> Results: We considered different conditions
  of atmospheric turbulence and photospheric regions with different
  mean magnetic strengths of 100 G and 200 G. As in non-magnetic cases
  studied in our previous work, the image correction by the AO system
  is mandatory for obtaining accurate measurements of the temperature
  gradient. We show that the non-magnetic line at 709 nm may be safely
  used in all the cases we have investigated. However, the intensity
  profile of the magnetic-sensitive line is broadened by the Zeeman
  effect, which would bias our temperature-gradient measurement. We thus
  implemented a correction procedure of the line profile for this magnetic
  broadening in the case of weakly magnetized regions. In doing so, we
  remarked that in the weak-field regime, the right- and left-hand (I +
  V and I - V) components have similar shapes, however, they are shifted
  in opposite directions due to the Zeeman effect. We thus reconstructed
  the intensity profile by shifting back the I + V and I - V profiles
  and by adding the re-centered profiles. The measurement then proceeds
  as in the non-magnetic case. We find that this correction procedure
  is efficient in regions where the mean magnetic strength is smaller or
  on the order of 100 G. <BR /> Conclusions: The new method we implement
  here may be used to measure the temperature gradient in the quiet Sun
  from ground-based telescopes equipped with an efficient AO system. We
  stress that we derive the gradient on a geometrical scale and not on an
  optical-depth scale as we would do with other standard methods. This
  allows us to avoid any confusion due to the effect of temperature
  variations on the continuum opacity in the solar photosphere.

---------------------------------------------------------
Title: Quantifying Properties of Photospheric Magnetic Cancellations
    in the Quiet Sun Internetwork
Authors: Ledvina, V.; Kazachenko, M.; Criscuoli, S.
2020AAS...23633003L    Altcode:
  We use spectropolarimetric data from the Swedish 1-meter Solar
  Telescope to investigate the physical properties of small-scale
  magnetic cancellations in the quiet sun photosphere. The CRisp Imaging
  SpectroPolarimeter (CRISP) captured a full Stokes polarization profile
  at Fe I 557.6 nm, which allowed to derive temporal evolution of the
  line-of-sight magnetic field during 42.5 minutes of QS evolution. From
  this magnetogram, we identified 38 cancellation events. We then
  used YAFTA magnetic element-tracking technique to derive various
  statistical physical properties of these cancellations. We found on
  average 1.558×10<SUP>16</SUP> Mx of magnetic flux being canceled in
  each event with an average cancellation rate of 3.816×10<SUP>14</SUP>
  Mx s<SUP>-1</SUP>. We found that derived canceled flux is associated
  with strong downflows, with an average speed of ΔV<SUB>LOS</SUB> of
  1.1 km s<SUP>-1</SUP>. Based on previous studies we surmise that these
  downflows lead to omega-loop submergence and magnetic reconnection. We
  found an average lifetime of each event to be 9.2 minutes with an
  average 44.8% of initial magnetic flux being canceled; these estimates,
  however, provide a lower limit since during cancellation events magnetic
  fields are frequently below the instrument noise level.

---------------------------------------------------------
Title: Comparing Radiative Transfer Codes and Opacity Samplings for
    Solar Irradiance Reconstructions
Authors: Criscuoli, Serena; Rempel, Matthias; Haberreiter, Margit;
   Pereira, Tiago M. D.; Uitenbroek, Han; Fabbian, Damian
2020SoPh..295...50C    Altcode:
  Some techniques developed to reproduce solar irradiance variations make
  use of synthetic radiative fluxes of quiet and magnetic features. The
  synthesis of radiative fluxes of astronomical objects is likely
  to be affected by uncertainties resulting from approximations and
  specific input employed for the synthesis. In this work we compare
  spectra obtained with three radiative transfer codes with the
  purpose of investigating differences in reproducing solar irradiance
  variations. Specifically, we compare spectral synthesis produced in
  non-local thermodynamic equilibrium obtained with COSI and RH using
  1-D atmosphere models. We also compare local thermodynamic equilibrium
  syntheses emerging from 3-D MURaM simulations of the solar atmosphere
  obtained with two sets of opacity tables generated with the ATLAS9
  package and with the RH code, and test the effects of opacity sampling
  on the emergent spectra. We find that, although the different codes
  and methodologies employed to synthesize the spectrum reproduce overall
  the observed solar spectrum with a similar degree of accuracy, subtle
  differences in quiet Sun spectra may translate into larger differences
  in the computation of the contrasts of magnetic features, which,
  in turn, critically affect the estimates of solar variability.

---------------------------------------------------------
Title: Recent progresses in the use of 3D MHD simulations for solar
    irradiance reconstructions
Authors: Criscuoli, Serena
2020IAUGA..30..333C    Altcode:
  The use of 3D magneto-hydrodynamic simulations of the solar
  atmosphere in modeling irradiance variations seems a natural
  evolution of the current irradiance reconstruction techniques making
  use of one-dimensional, static, atmosphere models. Nevertheless,
  the development of such new models poses serious computational
  challenges. This contribution focuses on recent progresses made in
  the development of novel irradiance reconstruction models making use
  of 3D MHD simulations and discusses current and future challenges.

---------------------------------------------------------
Title: Long-term (1749-2015) Variations of Solar UV Spectral Indices
Authors: Berrilli, Francesco; Criscuoli, Serena; Penza, Valentina;
   Lovric, Mija
2020SoPh..295...38B    Altcode:
  Solar radiation variability spans a wide range in time, ranging from
  seconds to decadal and longer. The nearly 40 years of measurements of
  solar irradiance from space established that the total solar irradiance
  varies by ≈0.1 % in phase with the Sun's magnetic cycle. Specific
  intervals of the solar spectrum, e.g., ultraviolet (UV), vary by orders
  of magnitude more. These variations can affect the Earth's climate
  in a complex non-linear way. Specifically, some of the processes
  of interaction between solar UV radiation and the Earth's atmosphere
  involve threshold processes and do not require a detailed reconstruction
  of the solar spectrum. For this reason a spectral UV index based on the
  (FUV-MUV) color has been recently introduced. This color is calculated
  using SORCE SOLSTICE integrated fluxes in the FUV and MUV bands. We
  present in this work the reconstructions of the solar (FUV-MUV) color
  and Ca II K and Mg II indices, from 1749-2015, using a semi-empirical
  approach based on the reconstruction of the area coverage of different
  solar magnetic features, i.e., sunspot, faculae and network. We remark
  that our results are in noteworthy agreement with latest solar UV proxy
  reconstructions that exploit more sophisticated techniques requiring
  historical full-disk observations. This makes us confident that our
  technique can represent an alternative approach which can complement
  classical solar reconstruction efforts. Moreover, this technique,
  based on broad-band observations, can be utilized to estimate the
  activity on Sun-like stars, that cannot be resolved spatially, hosting
  extra-solar planetary systems.

---------------------------------------------------------
Title: Continuum Enhancements, Line Profiles, and Magnetic Field
    Evolution during Consecutive Flares
Authors: Zuccarello, Francesca; Guglielmino, Salvo L.; Capparelli,
   Vincenzo; Mathioudakis, Mihalis; Keys, Peter H.; Criscuoli, Serena;
   Falco, Mariachiara; Murabito, Mariarita
2020ApJ...889...65Z    Altcode: 2019arXiv191200859Z
  During solar flares, magnetic energy can be converted into
  electromagnetic radiation from radio waves to γ-rays. Enhancements in
  the continuum at visible wavelengths, as well as continuum enhancements
  in the FUV and NUV passbands, give rise to white-light flares. In
  addition, the strong energy release in these events can lead to
  the rearrangement of the magnetic field at the photospheric level,
  causing morphological changes in large and stable magnetic structures
  like sunspots. In this context, we describe observations acquired
  by satellite instruments (Interface Region Imaging Spectrograph
  (IRIS), Solar Dynamics Observatory/Helioseismic and Magnetic Imager,
  Hinode/Solar Optical Telescope) and ground-based telescopes (Rapid
  Oscillations in the Solar Atmosphere (ROSA)/Dunn Solar Telescope)
  during two consecutive C7.0 and X1.6 flares that occurred in active
  region NOAA 12205 on 2014 November 7. The flare was accompanied by an
  eruption. The results of the analysis show the presence of continuum
  enhancements during the evolution of the events, observed both in ROSA
  images and in IRIS spectra. In the latter, a prominent blueshifted
  component is observed at the onset of the eruption. We investigate
  the role played by the evolution of the δ sunspots of the active
  region in the flare triggering, and finally we discuss the changes in
  the penumbrae surrounding these sunspots as a further consequence of
  these flares.

---------------------------------------------------------
Title: Solar Cycle-Related Variability of Sun-as-a-Star Spectral
    Line Profiles
Authors: Kalscheur, M.; Criscuoli, S.; Bertello, L.; Pevtsov, A. A.
2019AGUFMSH11D3390K    Altcode:
  We use daily observations of the Sun-as-a-star by the high resolution
  Integrated Sunlight Spectrometer (ISS), one of three instruments
  which comprise the Synoptic Optical Long-term Investigations of the
  Sun (SOLIS) facility, to investigate solar cycle-related variability
  in line profiles from three ISS spectral bands. Preliminary results
  show an anti-correlation between the magnitude of the CN band-head
  jump and total unsigned magnetic flux through the decline phase of
  Solar Cycle 23 and the rise and fall of Solar Cycle 24, consistent
  with magnetohydrodynamic simulations. Additional line parameters
  (core intensity, full width at half maximum and equivalent width)
  show correlations with the solar cycle, but may require correction
  for stray light. We investigate two such corrections. Varied line
  parameter responses to thermodynamic and magnetic structures in the
  solar atmosphere may provide a means of disentangling thermal and
  magnetic effects in disk-integrated solar spectra. These line parameter
  responses could in turn inform spectroscopic observations of other
  stars. Ultimately, this work is a step towards a better understanding
  of magnetic activity cycles in other Sun-like stars.

---------------------------------------------------------
Title: Quantifying Properties of Photospheric Magnetic Field
    Cancellation Events in the Quiet Sun Internetwork
Authors: Ledvina, V.; Kazachenko, M.; Criscuoli, S.
2019AGUFMSH43E3386L    Altcode:
  The behavior of the small-scale internetwork (IN) magnetic fields on
  the quiet sun is a frontier poorly understood. Since the quiet sun
  represents a majority of the Sun's flux output even during solar
  maximum, analyzing its processes is a key step in understanding
  the fundamental aspects of solar magnetism. IN cancellations in
  particular are important to characterize since they represent the
  major process occurring constantly on the quiet Sun. By observing
  these IN cancellations with high spatial and temporal resolutions
  with the Swedish 1m Solar Telescope (SST), we were able to analyze
  twelve cancellation events and describe their magnetic field
  properties. Applying a polarity-tracking algorithm, YAFTA, to a
  sequence of line-of-sight magnetograms, we found a mean cancellation
  flux of 1.11*10<SUP>17</SUP> Mx and a mean cancellation rate of
  1.61*10<SUP>14</SUP> Mx s<SUP>-1</SUP><SUP>.</SUP> Using the Doppler
  velocity at the PIL we found that all magnetic cancellations are
  associated with omega-loop submergence with a mean peak downflow speed
  of 1.02 km s<SUP>-1</SUP>, a figure statistically greater than regional
  convective downflow behavior. Analyzing the convergence speeds of the
  polarities suggests granular motions are the primary catalyst for IN
  cancellation events. Data gathered in this study complements existing
  understanding of magnetic behavior on the quiet Sun.

---------------------------------------------------------
Title: On the Challenges of synthetizing solar and stellar spectra
    for Irradiance reconstructions
Authors: Criscuoli, Serena; Rempel, Matthias D.; Haberreiter, Margit;
   Pereira, Tiago; Uitenbroek, Han; Fabbian, Damian
2019AAS...23421702C    Altcode:
  Syntheses of solar and stellar spectra strongly depend on the adopted
  approximations and atomic and molecular databases. We compare LTE and
  NLTE syntheses of solar spectra obtained with widely used radiative
  transfer codes, utilizing both 3D-MHD simulations and 1D-static
  atmosphere models. We show that although different codes reproduce
  reasonably well the observed spectrum, subtle differences may translate
  into discrepancies of several tens of percents in the estimate of
  solar and stellar spectral irradiance variability.

---------------------------------------------------------
Title: Historical reconstruction of UV spectral indices
Authors: Criscuoli, Serena; Berrilli, Francesco; Lovric, Mia; Penza,
   Valentina
2019AAS...23430205C    Altcode:
  Solar radiation is one of the major natural drivers of Earth
  climate changes observed from the Maunder minimum. UV radiation in
  particular plays a major role in the ozone production/destruction
  processes and is known to affect the circulation patterns. Here we
  present reconstructions of the FUV-MUV color index and CaII and MgII
  core-to-wing indeces from 1749-2015, performed with a semi-epirical
  approach. We also present a reconstruction of the TSI variability. Our
  results are compared with reconstructions obtained with models employed
  in climatological studies.

---------------------------------------------------------
Title: Developing a vision for exoplanetary transit spectroscopy:
    a shared window on the analysis of planetary atmospheres and of
    stellar magnetic structure
Authors: Kowalski, Adam; Schrijver, Karel; Pillet, Valentin; Criscuoli,
   Serena
2019BAAS...51c.149K    Altcode: 2019astro2020T.149K; 2019arXiv190405976K
  We describe how accurate exoplanet atmospheres' characterization will
  inevitably require taking into consideration stellar inhomogeneities
  caused by convection and magnetic fields. Disentangling these two
  components requires a multipronged approach with new solar reference
  spectra, MHD modeling, and collaborations among astrophysics
  communities.

---------------------------------------------------------
Title: Long-term reconstruction of Solar UV indices
Authors: Criscuoli, Serena; Berrilli, Francesco; Lovric, Mia; Penza,
   Valentina
2019shin.confE..80C    Altcode:
  Solar radiation is one of the major natural drivers of Earth climate
  variations. UV radiation in particular plays a major role in the ozone
  production/destruction processes and is known to affect the Earth's
  global circulation patterns. We present reconstructions of the FUV-MUV
  color index and CaII and MgII core-to-wing indices from 1749 to 2015,
  performed with a 4-components semi-empirical approach . Our model makes
  use of the Sunspot Number to estimate the UV color index and facula,
  network and sunspot area. The reconstructed UV indices, as well as
  the estimated area of magnetic structures, well compare with modern
  observations and historical records.

---------------------------------------------------------
Title: Effects of Continuum Fudging on Non-LTE Synthesis of Stellar
    Spectra. I. Effects on Estimates of UV Continua and Solar Spectral
    Irradiance Variability
Authors: Criscuoli, Serena
2019ApJ...872...52C    Altcode: 2018arXiv181205201C
  Syntheses performed under non-LTE conditions usually overestimate
  stellar spectra. An approach widely adopted in the literature to
  reduce the excess of UV radiation consists of artificially increasing
  the continuum opacity by using multiplicative fudge factors, which
  are empirically derived to impose that the synthetized spectrum
  match the observed one. Although the method was initially developed
  to improve non-LTE synthesis of spectral lines, it has been recently
  employed to model solar spectral irradiance variability. Such irradiance
  reconstruction techniques combine spectral synthesis of different types
  of structures, which are performed making use of factors derived from
  a reference, quiet-Sun model. Because the opacity scales in a complex
  way with plasma physical properties, the question arises whether, and
  to what extent, fudge factors derived using a reference model can be
  used to adjust the opacity of models representing different types of
  quiet and magnetic features. Here we investigate the effects of opacity
  fudging on estimates of solar and stellar irradiance variability in UV
  bands. We find that the use of fudge factors might underestimate the
  variability by 19% and up to 20% in the ranges 230-300 nm and 300-400
  nm, respectively. These estimates are model dependent and should be
  considered as upper limits. Finally, our analysis suggests that the
  uncertainties generated by the use of fudge factors increase with the
  decrease of stellar metallicity and are significant for stars whose
  variability is facula dominated and whose effective temperature is
  larger than ∼4000 K.

---------------------------------------------------------
Title: The Solar Photospheric Continuum Brightness as a Function of
    Mean Magnetic Flux Density. I. The Role of the Magnetic Structure
    Size Distribution
Authors: Peck, C. L.; Rast, M. P.; Criscuoli, S.; Rempel, M.
2019ApJ...870...89P    Altcode:
  Solar irradiance models indicate that irradiance variations are
  dominated by changes in the disk-coverage of magnetic structures,
  whose brightness is thought to be determined by their size and average
  magnetic flux density. Recent results suggest that the brightness of
  small-scale magnetic structures also depends on the mean magnetic flux
  of the extended region surrounding them due to reduced convective
  vigor. Low spatial resolution, however, may limit the ability to
  distinguish the role of magnetic structure size distributions from that
  of the mean magnetic flux. Using high-resolution 3D MHD simulations,
  we investigate the brightness of magnetic structures embedded in
  regions characterized by different mean magnetic flux. In agreement
  with previous results, we find reduced brightness with increasing
  mean magnetic flux when comparing the pixel-by-pixel continuum
  brightness versus magnetic field strength. Evaluating equivalently
  sized magnetic structures, however, we find no significant dependence
  of the magnetic structure brightness on the mean magnetic flux of the
  region in which they are embedded. Rather, we find that simulations
  with larger mean magnetic flux generate larger, and therefore darker,
  magnetic structures whose contributions result in an overall darkening
  of the region. The differences in magnetic structure size distributions
  alone can explain the reduced brightness of regions with larger mean
  magnetic flux. This implies that, for the range of mean magnetic flux
  of the simulations, convective suppression plays at most a secondary
  role in determining radiative output of magnetized regions. Quantifying
  the role of convective transport over a wider range of mean magnetic
  flux is the subject of the second paper in this series.

---------------------------------------------------------
Title: Preface
Authors: Bemporad, A.; Criscuoli, S.; Del Moro, D.; Guglielmino,
   S. L.; Landi, S.; Laurenza, M.; Reale, F.; Straus, T.; Vecchio, A.
2019NCimC..42....1B    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: The Correlation of Synthetic UV Color versus Mg II Index
    along the Solar Cycle
Authors: Criscuoli, Serena; Penza, Valentina; Lovric, Mija; Berrilli,
   Francesco
2018ApJ...865...22C    Altcode: 2018arXiv180808439C
  UV solar irradiance strongly affects the chemical and physical
  properties of the Earth’s atmosphere. UV radiation is also a
  fundamental input for modeling the habitable zones of stars and
  the atmospheres of their exoplanets. Unfortunately, measurements
  of solar irradiance are affected by instrumental degradation and
  are not available before 1978. For other stars, the situation is
  worsened by interstellar medium absorption. Therefore, estimates
  of solar and stellar UV radiation and variability often rely on
  modeling. Recently, Lovric et al. used Solar Radiation and Climate
  Experiment (SORCE)/Stellar Irradiance Comparison Experiment (SOLSTICE)
  data to investigate the variability of a color index that is a
  descriptor of the UV radiation that modulates the photochemistry of
  planets’ atmospheres. After correcting the SOLSTICE data for residual
  instrumental effects, the authors found the color index to be strongly
  correlated with the Mg II index, a solar activity proxy. In this paper,
  we employ an irradiance reconstruction to synthetize the UV color and Mg
  II index with the purpose of investigating the physical mechanisms that
  produce the strong correlation between the color index and the solar
  activity. Our reconstruction, which extends back to 1989, reproduces
  very well the observations, and shows that the two indices can be
  described by the same linear relation for almost three cycles, thus
  ruling out an overcompensation of SORCE/SOLTICE data in the analysis
  of Lovric et al. We suggest that the strong correlation between the
  indices results from the UV radiation analyzed originating in the
  chromosphere, where atmosphere models of quiet and magnetic features
  present similar temperature and density gradients.

---------------------------------------------------------
Title: Harmonizing Mangnetograph Data with end-to-end Instrument
    Simulations
Authors: Plowman, J.; Petrie, G. J. D.; Pillet, V. M.; Criscuoli,
   S.; Harvey, J. W.; Marble, A.; Uitenbroek, H.
2017AGUFMSH13A2460P    Altcode:
  There are a number of instruments, such as NSO's GONG and SOLIS/VSM,
  which measure the magnetic field of the Sun's photosphere. However,
  their measurements are not fully consistent, and the factors responsible
  for the differences have yet to be isolated. I report on a new effort
  to resolve them - we simulate the observing processes from end to
  end, beginning with 3D MHD simulations. This allows us to compare the
  synthetic observations produced with the MHD simulations' 'ground truth'
  and identify the effects of the observational factors at play. The
  result will be the best ever calibration of a magnetograph, giving
  magnetic field models based on these data a much firmer foundation.

---------------------------------------------------------
Title: An Assessment of and Solution to the Intensity Diffusion
    Error Intrinsic to Short-characteristic Radiative Transfer Methods
Authors: Peck, C. L.; Criscuoli, S.; Rast, M. P.
2017ApJ...850....9P    Altcode: 2017arXiv170809362P
  Radiative transfer coupled with highly realistic simulations of the
  solar atmosphere is routinely used to infer the physical properties
  underlying solar observations. Due to its computational efficiency,
  the method of short-characteristics is often employed, despite it
  introducing numerical diffusion as an interpolation artifact. In this
  paper, we quantify the effect of the numerical diffusion on the spatial
  resolution of synthesized emergent intensity images, and derive a
  closed form analytical model of the diffusive error made as a function
  of viewing angle when using linear interpolation. We demonstrate that
  the consequent image degradation adversely affects the comparison
  between simulated data and observations away from disk center, unless
  the simulations are computed at much higher intrinsic resolutions than
  the observations. We also show that the diffusive error is readily
  avoided by interpolating the simulation solution on a viewing angle
  aligned grid prior to computing the radiative transfer. Doing this
  will be critical for comparisons with observations using the upcoming
  large aperture telescopes—the Daniel K. Inouye Solar Telescope and
  the European Solar Telescope.

---------------------------------------------------------
Title: Photometric Properties of Network and Faculae Derived from
    HMI Data Compensated for Scattered Light
Authors: Criscuoli, Serena; Norton, Aimee; Whitney, Taylor
2017ApJ...847...93C    Altcode: 2017arXiv170901593C
  We report on the photometric properties of faculae and network,
  as observed in full-disk, scattered-light-corrected images from the
  Helioseismic Magnetic Imager. We use a Lucy-Richardson deconvolution
  routine that corrects an image in less than one second. Faculae are
  distinguished from network through proximity to active regions. This is
  the first report that full-disk observations, including center-to-limb
  variations, reproduce the photometric properties of faculae and
  network observed previously only in sub-arcsecond-resolution; small
  field-of-view studies, I.e. that network, as defined by distance from
  active regions, exhibit higher photometric contrasts. Specifically,
  for magnetic flux values larger than approximately 300 G, the network
  is brighter than faculae and the contrast differences increase toward
  the limb, where the network contrast is about twice the facular one. For
  lower magnetic flux values, network appear darker than faculae. Contrary
  to reports from previous full-disk observations, we also found that
  network exhibits a higher center-to-limb variation. Our results are
  in agreement with reports from simulations that indicate magnetic
  flux alone is a poor proxy of the photometric properties of magnetic
  features. We estimate that the contribution of faculae and network
  to Total Solar Irradiance variability of the current Cycle 24 is
  overestimated by at least 11%, due to the photometric properties of
  network and faculae not being recognized as different. This estimate
  is specific to the method employed in this study to reconstruct
  irradiance variations, so caution should be paid when extending it to
  other techniques.

---------------------------------------------------------
Title: The variability of magnetic activity in solar-type stars
Authors: Fabbian, D.; Simoniello, R.; Collet, R.; Criscuoli, S.;
   Korhonen, H.; Krivova, N. A.; Oláh, K.; Jouve, L.; Solanki, S. K.;
   Alvarado-Gómez, J. D.; Booth, R.; García, R. A.; Lehtinen, J.;
   See, V.
2017AN....338..753F    Altcode:
  No abstract at ADS

---------------------------------------------------------
Title: Photometric Properties of Network and faculae derived by HMI
    data compensated for scattered-light
Authors: Criscuoli, Serena; Norton, Aimee Ann; Whitney, Taylor
2017SPD....4820703C    Altcode:
  We report on the photometric properties of faculae and network
  as observed in full-disk,scattered-light corrected images from
  the Helioseismic Magnetic Imager (HMI). We usea Lucy-Richardson
  deconvolution routine that corrects a full-disk intensity image in
  lessthan one second. Faculae are distinguished from network through
  proximity to activeregions in addition to continuum intensity and
  magnetogram thresholds. This is the firstreport that full-disk image
  data, including center-to-limb variations, reproduce the photometric
  properties of faculae and network observed previously only in
  sub-arcsecond resolution, small field-of-view studies, i.e. that network
  exhibit in general higher photometric contrasts. More specifically,
  for magnetic flux values larger than approximately 300 G, the network
  is always brighter than faculae and the contrast differences increases
  toward the limb, where the network contrast is about twice the facular
  one. For lower magnetic flux values, pixels in network regions appear
  always darker than facular ones. Contrary to reports from previous
  full-disk observations, we also found that network exhibits a higher
  center-to-limb variation. Our results are in agreement with reports
  from simulations that indicate magnetic flux alone is a poor proxy
  of the photometric properties of magnetic features. We estimate
  that the facular and network contribution to irradiance variability
  of the current Cycle 24 is overestimated by at least 11% due to the
  photometric properties of network and faculae not being recognized as
  distinctly different.

---------------------------------------------------------
Title: Assessing the Impact of Small-Scale Magnetic Morphology on
    Solar Variability
Authors: Peck, Courtney; Rast, Mark; Criscuoli, Serena
2017SPD....48.0503P    Altcode:
  Spectral solar irradiance (SSI), the radiant energy flux per wavelength
  of the Sun received at Earth, is an important driver of chemical
  reactions in the Earth’s atmosphere. Accurate measurements of SSI are
  therefore necessary as an input for global climate models. While models
  and observations of the spectrally-integrated total solar irradiance
  (TSI) variations agree within ∼ 95%, they can disagree on the sign
  and magnitude of the SSI variations. In this work, we examine the
  contribution of currently-unresolved small-scale magnetic structures
  to SSI variations in the photosphere. We examine the emergent spectra
  of two atmospheres with differing imposed-field conditions — one
  with a small-scale dynamo and the other with a predominantly vertical
  magnetic field — with similar mean field strengths at wavelengths
  spanning from visible to infrared. Comparing the radiative output at
  various viewing angles of pixels of equal vertical magnetic field
  strength between the two simulations, we find that the small-scale
  dynamo simulations produce higher radiative output than those in the
  predominantly vertical field simulation. This implies that the radiative
  output of a small magnetic structure depends on the magnetic morphology
  of the environment in which it is embedded, which is currently not
  included in SSI models. We deduce the effect on inferred irradiance
  by comparing the disk-integrated irradiance of these two atmospheres
  with standard 1D model atmospheres used in SSI modeling.

---------------------------------------------------------
Title: Assessment of and a Solution to the Intensity Diffusion Error
    Intrinsic in Short-Characteristic Radiative Transfer
Authors: Peck, Courtney; Rast, Mark; Criscuoli, Serena
2017SPD....4820701P    Altcode:
  Short characteristic radiative transfer coupled with 3D MHD simulations
  are routinely used to compare simulations with observations of the
  solar atmosphere. While it has been known that the method of short
  characteristics radiative transfer results in intensity diffusion,
  it has been routinely employed to solve radiative transfer due to
  its computational expediency. In this talk, we discuss the effect
  of spatial smearing due to short characteristics radiative transfer
  under both linear and high-order interpolation. We then demonstrate
  that linear interpolation results in an effective spatial smearing
  related to the number of grid heights above the τ = 1 surface and
  conserves intensity. Additionally, we show that the use of high-order
  strict monotonic interpolation reduces the amount of smearing, but at
  the expense of error in the integrated emergent intensity. Finally,
  we demonstrate that these issues can be easily avoided at no
  added computational expense by interpolating the atmosphere onto a
  ray-directed grid and computing the radiative transfer for vertical
  rays through the grid.

---------------------------------------------------------
Title: Polarized Kink Waves in Magnetic Elements: Evidence for
    Chromospheric Helical Waves
Authors: Stangalini, M.; Giannattasio, F.; Erdélyi, R.; Jafarzadeh,
   S.; Consolini, G.; Criscuoli, S.; Ermolli, I.; Guglielmino, S. L.;
   Zuccarello, F.
2017ApJ...840...19S    Altcode: 2017arXiv170402155S
  In recent years, new high spatial resolution observations of the Sun's
  atmosphere have revealed the presence of a plethora of small-scale
  magnetic elements down to the resolution limit of the current cohort
  of solar telescopes (∼100-120 km on the solar photosphere). These
  small magnetic field concentrations, due to the granular buffeting,
  can support and guide several magnetohydrodynamic wave modes that
  would eventually contribute to the energy budget of the upper layers
  of the atmosphere. In this work, exploiting the high spatial and
  temporal resolution chromospheric data acquired with the Swedish
  1 m Solar Telescope, and applying the empirical mode decomposition
  technique to the tracking of the solar magnetic features, we analyze
  the perturbations of the horizontal velocity vector of a set of
  chromospheric magnetic elements. We find observational evidence that
  suggests a phase relation between the two components of the velocity
  vector itself, resulting in its helical motion.

---------------------------------------------------------
Title: A Study of Solar Photospheric Temperature Gradient Variation
    Using Limb Darkening Measurements
Authors: Criscuoli, Serena; Foukal, Peter
2017ApJ...835...99C    Altcode: 2016arXiv161110201C
  The variation in area of quiet magnetic network measured over the
  sunspot cycle should modulate the spatially averaged photospheric
  temperature gradient, since temperature declines with optical depth
  more gradually in magnetic flux tube atmospheres. Yet, limb darkening
  measurements show no dependence upon activity level, even at an rms
  precision of 0.04%. We study the sensitivity of limb darkening to
  changes in area filling factor using a 3D MHD model of the magnetized
  photosphere. The limb darkening change expected from the measured
  11-year area variation lies below the level of measured limb darkening
  variations, for a reasonable range of magnetic flux in quiet network
  and internetwork regions. So the remarkably constant limb darkening
  observed over the solar activity cycle is not inconsistent with
  the measured 11-year change in area of quiet magnetic network. Our
  findings offer an independent constraint on photospheric temperature
  gradient changes reported from measurements of the solar spectral
  irradiance from the Spectral Irradiance Monitor, and recently, from
  wavelength-differential spectrophotometry using the Solar Optical
  Telescope aboard the HINODE spacecraft.

---------------------------------------------------------
Title: Lower solar atmosphere and magnetism at ultra-high spatial
    resolution
Authors: Collet, Remo; Criscuoli, Serena; Ermolli, Ilaria; Fabbian,
   Damian; Guerreiro, Nuno; Haberreiter, Margit; Peck, Courtney; Pereira,
   Tiago M. D.; Rempel, Matthias; Solanki, Sami K.; Wedemeyer-Boehm, Sven
2016arXiv161202348C    Altcode:
  We present the scientific case for a future space-based telescope
  aimed at very high spatial and temporal resolution imaging of the
  solar photosphere and chromosphere. Previous missions (e.g., HINODE,
  SUNRISE) have demonstrated the power of observing the solar photosphere
  and chromosphere at high spatial resolution without contamination from
  Earth's atmosphere. We argue here that increased spatial resolution
  (from currently 70 km to 25 km in the future) and high temporal cadence
  of the observations will vastly improve our understanding of the
  physical processes controlling solar magnetism and its characteristic
  scales. This is particularly important as the Sun's magnetic field
  drives solar activity and can significantly influence the Sun-Earth
  system. At the same time a better knowledge of solar magnetism can
  greatly improve our understanding of other astrophysical objects.

---------------------------------------------------------
Title: Kinematics and Magnetic Properties of a Light Bridge in a
    Decaying Sunspot
Authors: Falco, M.; Borrero, J. M.; Guglielmino, S. L.; Romano, P.;
   Zuccarello, F.; Criscuoli, S.; Cristaldi, A.; Ermolli, I.; Jafarzadeh,
   S.; Rouppe van der Voort, L.
2016SoPh..291.1939F    Altcode: 2016arXiv160607229F; 2016SoPh..tmp..107F
  We present the results obtained by analysing high spatial and spectral
  resolution data of the solar photosphere acquired by the CRisp Imaging
  SpectroPolarimeter at the Swedish Solar Telescope on 6 August 2011 of a
  large sunspot with a light bridge (LB) observed in NOAA AR 11263. These
  data are complemented by simultaneous Hinode Spectropolarimeter (SP)
  observation in the Fe I 630.15 nm and 630.25 nm lines. The continuum
  intensity map shows a discontinuity in the radial distribution of the
  penumbral filaments in correspondence with the LB, which shows a dark
  lane (≈0.3<SUP>″</SUP> wide and ≈8.0<SUP>″</SUP> long) along its
  main axis. The available data were inverted with the Stokes Inversion
  based on Response functions (SIR) code and physical parameters maps were
  obtained. The line-of-sight (LOS) velocity of the plasma along the LB
  derived from the Doppler effect shows motions towards and away from the
  observer up to 0.6 kms−<SUP>1</SUP> that are lower in value than the
  LOS velocities observed in the neighbouring penumbral filaments. The
  noteworthy result is that we find motions towards the observer of up to
  0.6 kms−<SUP>1</SUP> in the dark lane where the LB is located between
  two umbral cores, while the LOS velocity motion towards the observer
  is strongly reduced where the LB is located between an umbral core
  at one side and penumbral filaments on the other side. Statistically,
  the LOS velocities correspond to upflows or downflows, and comparing
  these results with Hinode/SP data, we conclude that the surrounding
  magnetic field configuration (whether more or less inclined) could have
  a role in maintaining the conditions for the process of plasma pile-up
  along the dark lane. The results obtained from our study support and
  confirm outcomes of recent magneto-hydrodynamic simulations showing
  upflows along the main axis of an LB.

---------------------------------------------------------
Title: Angular Dependence of the Facular-Sunspot Coverage Relation
    as Derived by MDI Magnetograms
Authors: Criscuoli, S.
2016SoPh..291.1957C    Altcode: 2016SoPh..tmp..108C; 2016arXiv160604851C
  Previous studies have shown that the variation over the solar magnetic
  activity cycle of the area of facular/network features identified from
  broad-band and narrow-band imagery is positively correlated with the
  sunspot area and number, the relation being described as either linear
  or quadratic. On the other hand, the temporal variation of the spatial
  distributions of faculae, network and sunspots follows patterns that
  are less obviously correlated, so that we expect the relation that
  describes variation of the area coverage of different types of magnetic
  features to vary with the position over the disk. In this work we employ
  Michelson Doppler Interferometer (MDI) full-disk magnetograms acquired
  during solar cycle 23 and at the beginning of cycle 24 to investigate
  the relation between the coverage of magnetic elements characterized
  by different amounts of magnetic flux and located at different angular
  distances from disk center with the sunspot number. In agreement with
  some previous studies we find that daily data are best described by
  a quadratic function while data averaged over six months are best
  described by a linear function. In both cases the coefficients of
  the fits show large dependence on the position over the disk and
  the magnetic flux. We also find that toward disk center six-month
  averaged data show asymmetries between the ascending and the descending
  phases. The implications for solar irradiance modeling are discussed.

---------------------------------------------------------
Title: Relation between Intensity Contrast and Magnetic Field for
    Active and Quiet Regions Observed on the Solar Photosphere
Authors: Whitney, Taylor; Criscuoli, Serena; Norton, Aimee Ann
2016SPD....47.1209W    Altcode:
  Current solar modeling techniques assume that active and quiet regions
  can be considered in the same manner. However, recent results from
  numerical simulations and high-spatial resolution observations indicate
  that radiative properties of small magnetic elements depend on whether
  they are located in plages, network, or quiet areas. These studies have
  been carried out typically at, or close to, disk center. In this study,
  data from the Helioseismic Magnetic Imager (HMI) are used to investigate
  the differences between magnetic elements located in Network/Quiet and
  Active Regions (AR) observed at different positions over the solar disk.

---------------------------------------------------------
Title: Investigation of photospheric temperature gradient variations
    using limb darkening measurements and simulations
Authors: Criscuoli, Serena; Foukal, Peter V.
2016SPD....4730301C    Altcode:
  The temperature stratifications of magnetic elements and unmagnetized
  plasma are different, so that changes of the facular and network
  filling factor over the cycle modify the average temperature gradient
  in the photosphere.Such variations have been suggested to explain
  irradiance measurements obtained by the SIM spectrometers in he
  visible and infrared spectral ranges. On the other hand, limb darkening
  measurements show no dependence upon activity level. We investigate the
  sensitivity of limb darkening to changes in network area filling factor
  using a 3-D MHD model of the magnetized photosphere. We find that the
  expected limb darkening change due to the measured 11- yr variation
  in filling factor lies outside the formal 99% confidence limit of
  the limb darkening measurements. This poses important constraints for
  observational validation of 3D-MHD simulations.

---------------------------------------------------------
Title: Facular-sunspot coverage relation derived by MDI magnetograms
Authors: Criscuoli, Serena
2016SPD....47.1003C    Altcode:
  We employ MDI full-disk magnetograms acquired during Cycle 23 and
  at the beginning of Cycle 24 to investigate the relation between
  the filling factor of magnetic elements characterized by different
  amount of magnetic flux and located at different angular distance from
  disk center with the sunspot number. In agreement with some previous
  studies we find that daily data are best described by a quadratic
  function while data averaged over 6-months are best described by a
  linear function. In both cases the coefficients of the fits show large
  dependence on the position over the disk and the magnetic flux. We also
  find that toward disk center 6-months averaged data show asymmetries
  between the ascending and the descending phase.

---------------------------------------------------------
Title: Interpreting Irradiance Distributions Using High-Resolution
    3D MHD Simulations
Authors: Peck, Courtney; Rast, Mark; Criscuoli, Serena; Uitenbroek,
   Han; Rempel, Matthias D.
2016SPD....4730302P    Altcode:
  We present initial results of studies aimed at understanding the
  impact of the unresolved magnetic field distribution on solar spectral
  irradiance. Using high-resolution 3D MHD simulations (from MURaM code)
  and spectral synthesis (with the RH code), we examine the emergent
  spectra of two atmospheres with similar mean field strengths but
  differing imposed-field conditions at wavelengths spanning from
  visible to infrared. Comparing the contrast against the magnetic
  field strength for the two magnetic simulations, we find differences
  in the distributions of contrasts versus field strength. We repeat
  the analysis after convolving the images with the PSF of a typical
  solar telescope (1-meter) and discuss the potential implications for
  irradiance modeling and future steps.

---------------------------------------------------------
Title: A Multi-instrument Analysis of a C4.1 Flare Occurring in a
    δ Sunspot
Authors: Guglielmino, S. L.; Zuccarello, F.; Romano, P.; Cristaldi,
   A.; Ermolli, I.; Criscuoli, S.; Falco, M.; Zuccarello, F. P.
2016ApJ...819..157G    Altcode:
  We present an analysis of multi-instrument space- and ground-based
  observations relevant to a C4.1 solar flare that occurred in the
  active region (AR) NOAA 11267 on 2011 August 6. Solar Dynamics
  Observatory observations indicate that at the flare’s beginning,
  it was localized in the preceding sunspot of the AR, which exhibits
  a δ configuration. Along the polarity inversion line between its
  opposite polarities we find a large shear angle of about 80°. The
  helicity accumulation shows that the AR does not obey the general
  hemispheric helicity rule. At the flare peak, unique observations
  taken with the X-Ray Telescope aboard Hinode reveal that the bulk
  of the X-ray emission takes place in the δ-spot region, where
  the plasma heats up to ≈ 1.9\cdot {10}<SUP>7</SUP> K. During the
  gradual phase, we observe the development of a Y-shaped structure in
  the corona and in the high chromosphere. An extruding structure forms,
  being directed from the emitting region above the δ spot toward the
  following sunspot. This structure cools down in a few tens of minutes
  while moving eastward along a direction opposite to the flare ribbon
  expansion. Finally, remote brightenings are found at the easternmost
  footpoint of this structure, appearing as a third flare ribbon in the
  chromosphere. After some minutes, RHESSI measurements show that the
  X-ray emission is localized in the region close to the crossing point
  of the coronal Y-shaped structure. Simultaneously, high-resolution
  (0.″15) observations performed at the Swedish 1 m Solar Telescope
  indicate a decreasing trend of the Ca II H intensity in the flare
  ribbons with some transient enhancements. All these findings suggest
  that this event is a manifestation of magnetic reconnection, likely
  induced by an asymmetric magnetic configuration in a highly sheared
  region.

---------------------------------------------------------
Title: The Effects of Magnetic Field Morphology on the Determination
    of Oxygen and Iron Abundances in the Solar Photosphere
Authors: Moore, Christopher S.; Uitenbroek, Han; Rempel, Matthias;
   Criscuoli, Serena; Rast, Mark
2016AAS...22712501M    Altcode:
  The solar chemical abundance (or a scaled version of it) is
  implemented in numerous astrophysical analyses. Thus, an accurate
  and precise estimation of the solar elemental abundance is crucial
  in astrophysics.We have explored the impact of magnetic fields
  on the determination of the solar photospheric oxygen andiron
  abundances using 3D radiation-magnetohydrodynamic (MHD) simulations
  of convection. Specifically, weexamined differences in abundance
  deduced from three classes of atmospheres simulated with the MURaM
  code: apure hydrodynamic (HD) simulation, an MHD simulation with
  a local dynamo magnetic field that has saturated withan unsigned
  vertical field strength of 80 G at the optical depth unity surface,
  and an MHD simulation with an initially imposed vertical mean field
  of 80 G. We use differential equivalent width analysis for diagnosing
  abundances derived from five oxygen and four iron spectral lines of
  differing wavelength, oscillator strength, excitation potential, and
  Lande g-factor, and find that the morphology of the magnetic field
  is important to the outcome of abundance determinations. The largest
  deduced abundance differences are found in the vertical mean field
  simulations and small scale unresolved field resulting from the local
  dynamo has a smaller impact on abundance determinations.

---------------------------------------------------------
Title: Merging of small-size magnetic elements observed at the
    Swedish Solar Tower
Authors: Criscuoli, Serena
2015TESS....120105C    Altcode:
  We investigate the evolution of physical properties of small-size
  magnetic elements of the same polarity during merging. We found
  that at the merging the line of sight velocity and magnetic flux
  abruptly change, while the photometric contrast increases with a
  delay proportional to the formation height of the observed wavelength
  range. These results suggest that the merging causes MHD perturbations
  propagating from the photosphere to the higher layers of the atmosphere.

---------------------------------------------------------
Title: Understanding the Fe I Line Measurements Returned by the
    Helioseismic and Magnetic Imager (HMI)
Authors: Cohen, D. P.; Criscuoli, S.; Farris, L.; Tritschler, A.
2015SoPh..290..689C    Altcode: 2015SoPh..tmp...17C; 2015arXiv150202559C
  The Helioseismic and Magnetic Imager (HMI) onboard the Solar Dynamics
  Observatory (SDO) observes the Sun at the Fe I 6173 Å line and
  returns full-disk maps of line-of-sight (LOS) observables including
  the magnetic flux density, velocities, Fe I line width, line depth, and
  continuum intensity. These data are estimated through an algorithm (the
  MDI-like algorithm, hereafter) that combines observables obtained at six
  wavelength positions within the Fe I 6173 Å line. To properly interpret
  such data, it is important to understand any effects of the instrument
  and of the pipeline that generates these data products. We tested
  the accuracy of the line width, line depth, and continuum intensity
  returned by the MDI-like algorithm using various one-dimensional (1D)
  atmosphere models. It was found that HMI estimates of these quantities
  are highly dependent on the shape of the line, therefore on the LOS
  angle and the magnetic flux density associated with the model, and less
  to line shifts with respect to the central positions of the instrument
  transmission profiles. In general, the relative difference between
  synthesized values and HMI estimates increases toward the limb and
  with the increase of the field; the MDI-like algorithm seems to fail
  in regions with fields larger than approximately 2000 G. Instrumental
  effects were investigated by analyzing HMI data obtained at daily
  intervals for a span of three years at disk center in the quiet Sun
  and hourly intervals for a span of 200 hours. The analysis revealed
  periodicities induced by the variation of the orbital velocity of the
  observatory with respect to the Sun, and long-term trends attributed to
  instrument adjustments, re-calibrations, and instrumental degradation.

---------------------------------------------------------
Title: The Signature of Flare Activity in Multifractal Measurements
    of Active Regions Observed by SDO/HMI
Authors: Giorgi, F.; Ermolli, I.; Romano, P.; Stangalini, M.;
   Zuccarello, F.; Criscuoli, S.
2015SoPh..290..507G    Altcode: 2017arXiv170506708G; 2014SoPh..tmp..132G
  Recent studies indicate that measurements of fractal and multifractal
  parameters of active regions (ARs) are inefficient tools for
  distinguishing ARs on the basis of the flare activity or to predict
  flare events. In an attempt to validate this result on a large
  observation data set of higher spatial and temporal resolution and
  higher flux sensitivity than employed in previous studies, we analyzed
  high-cadence time series of line-of-sight magnetograms of 43 ARs
  characterized by different flare activity, which were observed with
  SDO/HMI from May 2010 to December 2013. On these data, we estimated
  four parameters, the generalized fractal dimensions D<SUB>0</SUB> and
  D<SUB>8</SUB>, and the multifractal parameters C<SUB>div</SUB> and
  D<SUB>div</SUB>. We found distinct average values of the parameters
  measured on ARs that have hosted flares of different class. However,
  the dispersion of values measured on ARs that have produced the same
  class of events is such that the parameters deduced from distinct
  classes of flaring regions can also largely overlap. Based on the
  results of our measurements, C- and M-class flaring ARs are practically
  indistinguishable, and the same is true for M- and X-class flaring
  ARs. We only found consistent changes on the time series of the
  measured parameters on ≈ 50 % of the ARs and ≈ 50 % of the M-
  and X-class events. We show that these results hold for fractal and
  multifractal parameter estimates based on total unsigned and signed
  flux data of the ARs.

---------------------------------------------------------
Title: The Effects of Magnetic Field Morphology on the Determination
    of Oxygen and Iron Abundances in the Solar Photosphere
Authors: Moore, Christopher S.; Uitenbroek, Han; Rempel, Matthias;
   Criscuoli, Serena; Rast, Mark P.
2015ApJ...799..150M    Altcode:
  We have explored the impact of magnetic fields on the determination
  of the solar photospheric oxygen and iron abundances using
  three-dimensional radiation-magnetohydrodynamic (MHD) simulations
  of convection. Specifically, we examined differences in abundance
  deduced from three classes of atmospheres simulated with the MURaM
  code: a pure hydrodynamic (HD) simulation, an MHD simulation with
  a local dynamo magnetic field that has saturated with an unsigned
  vertical field strength of 80 G at τ = 1, and an MHD simulation with
  an initially imposed vertical mean field of 80 G. We use differential
  equivalent width analysis for diagnosing abundances derived from
  five oxygen and four iron lines of differing wavelength, oscillator
  strength, excitation potential, and Landé g-factor, and find that
  the morphology of the magnetic field is important to the outcome of
  abundance determinations. The largest deduced abundance differences are
  found in the vertical mean field simulations, where the O I and Fe I
  abundance corrections compared to the pure HD case are ~+0.011 dex and
  +0.065 dex respectively. Small scale unresolved field resulting from
  the local dynamo has a smaller impact on abundance determinations,
  with corrections of -0.0001 dex and +0.0044 dex in the magnetized
  compared to the pure HD simulations. While the overall influence of
  magnetic field on abundance estimates is found to be small, we stress
  that such estimates are sensitive not only to the magnitude of magnetic
  field but also to its morphology.

---------------------------------------------------------
Title: Angular Variation of Solar Feature Contrast in Full-Disk
    G-Band Images
Authors: Blunt, Sarah Caroline; Criscuoli, Serena; Ermolli, Ilaria;
   Giorgi, Fabrizio
2015AAS...22513703B    Altcode:
  We investigate the center-to-limb variation (CLV) of the contrasts of
  four types of solar surface features observed in the G-Band (430.6 nm,
  FWHM 1.2 nm) by analyzing 12 high quality full-disk images obtained
  from the Rome Precision Solar Photometric Telescope. The studied
  features, specifically network, enhanced network, plage, and bright
  plage, were singled out based on their brightness signatures in mean
  simultaneous Ca II K images using an intensity threshold technique. We
  compared our results with those obtained from high-resolution (HR)
  observations, and with the outputs of the spectral synthesis performed
  on semi-empirical models and magneto hydrodynamic (MHD) simulations. We
  find that the measured contrasts are systematically lower than those of
  HR observational results, as was expected due to the lower resolution
  of the analyzed observations. We also find that our observations best
  reflect the CLV derived from the recent one-dimensional atmospheric
  models described in Fontenla et al 2011 with respect to results obtained
  from earlier similar models. The measured CLV also agrees with those
  derived from the syntheses of MHD simulations and HR observations,
  if spatial resolution effects are properly taken into account. This
  work was carried out through the National Solar Observatory Summer
  Research Assistantship (SRA) Program. The National Solar Observatory is
  operated by the Association of Universities for Research in Astronomy,
  Inc. (AURA) under cooperative agreement with the National Science
  Foundation. This work was also partially supported by the European
  Union's Seventh Programme for Research, Technological Development
  and Demonstration under the grant agreements in 312495 (SOLARNET)
  and 313188 (SOLID).

---------------------------------------------------------
Title: Dynamical behaviour of photospheric bright points during
    merging
Authors: Criscuoli, S.; Stangalini, M.; Ermolli, I.; Zuccarello, F.;
   Cristaldi, A.; Falco, M.; Guglielmino, S.; Giorgi, F.
2014AGUFMSH41C4152C    Altcode:
  We investigate the merging of bright points observed at high spatial
  and temporal resolution with CRISP/SST in a quiet region region. We
  analyze the MHD perturbations excited during the merging, their role
  in the energy budget of the magnetic structure and the potential role
  that they can play in heating the upper layers of the Sun's atmosphere.

---------------------------------------------------------
Title: "Future Solar Physics with the Daniel K. Inouye Solar Telescope
    (DKIST)"
Authors: Criscuoli, S.
2014AGUFMSH31C..02C    Altcode:
  During the last decades, the synergistic development of large
  aperture telescopes and real time and post facto techniques for
  image degradation correction, have allowed observations of the solar
  atmosphere at resolutions up to tens of arcsecond. The analysis of
  these data, together with the development of sophisticated inversion
  techniques to infer properties of the magnetic field, have largely
  improved our understanding of many aspects of solar physics which
  include the nature and properties of small scale magnetic elements,
  the fine structuring of sunspots, the properties of granulation and
  its interaction with the magnetic field, the propagation of waves
  from the photosphere to the chromosphere, the highly dynamics and
  fine structuring of the chromosphere. Still several issues, like the
  origin and nature of the photospheric magnetism, especially in the
  quiet Sun, the properties of the chromospheric magnetic field, the
  chromospheric energy budget, and the properties of the photospheric
  and chromospheric plasma and magnetic field during eruptive events,
  remain open. Moreover, state-of-the-art magneto hydrodynamic simulations
  produce structures down to the spatial resolution of the simulations
  themselves (generally, few kilometers per pixel), which are unresolved
  in current observations. The Daniel K. Inouye Solar Telescope (DKIST),
  with its four meter aperture and state-of-the-art adaptive optics, will
  allow the acquisition of hundredths of arcsecond spatial resolution
  data. In this contribution I review the main open questions that the
  analysis of DKIST observations will allow to address.

---------------------------------------------------------
Title: Fractal and Multifractal Properties of Active Regions as Flare
Precursors: A Case Study Based on SOHO/MDI and SDO/HMI Observations
Authors: Ermolli, I.; Giorgi, F.; Romano, P.; Zuccarello, F.;
   Criscuoli, S.; Stangalini, M.
2014SoPh..289.2525E    Altcode: 2014SoPh..tmp...38E
  Several studies indicate that fractal and multifractal parameters
  inferred from solar photospheric magnetic field measurements may
  help assessing the eruptive potential of Active Regions (ARs) and
  also predicting their flare activity. We further investigate this
  topic, by exploring the sensitivity of some parameters already
  used in the literature on data and methods employed for their
  estimation. In particular, we measured the generalized fractal
  dimensions D<SUB>0</SUB> and D<SUB>8</SUB>, and the multifractal
  parameters C<SUB>div</SUB> and D<SUB>div</SUB>, on the time series of
  photospheric magnetograms of the flaring AR NOAA 11158 obtained with
  the SOHO/MDI and SDO/HMI. The observations by the latter instrument are
  characterized by a higher spatial and temporal resolution, as well as
  higher flux sensitivity, than the ones obtained from SOHO/MDI, which
  were widely employed in earlier studies. We found that the average
  and peak values of complexity parameters measured on the two data sets
  agree within measurement uncertainties. The temporal evolution of the
  parameters measured on the two data sets show rather similar trends,
  but the ones derived from the SOHO/MDI observations show larger and
  spurious variations over time than those deduced from analysis of
  the corresponding SDO/HMI data. We also found a larger sensitivity
  of these measurements to characteristics of the data analyzed than
  reported by earlier studies. In particular, analysis of the higher
  resolution and higher cadence SDO/HMI data allows us also to detect
  slight variations of the complexity indicators that cannot be derived
  from the analysis of the SOHO/MDI data. These variations occur right
  after the major events in the analyzed AR. They may be the signature
  of photospheric effects of coronal magnetic field re-arrangement.

---------------------------------------------------------
Title: Dynamic Properties along the Neutral Line of a Delta Spot
    Inferred from High-resolution Observations
Authors: Cristaldi, A.; Guglielmino, S. L.; Zuccarello, F.; Romano,
   P.; Falco, M.; Rouppe van der Voort, L.; de la Cruz Rodríguez, J.;
   Ermolli, I.; Criscuoli, S.
2014ApJ...789..162C    Altcode:
  Delta (δ) spots are complex magnetic configurations of sunspots
  characterized by umbrae of opposite polarity sharing a common
  penumbra. In order to investigate the fine structure of the region
  separating the two magnetic polarities of a δ spot, we studied the
  morphology, the magnetic configuration, and the velocity field in
  such a region using observations of active region (AR) NOAA 11267
  obtained with the CRisp Imaging SpectroPolarimeter (CRISP) at the
  Swedish Solar Telescope on 2011 August 6. The analysis of CRISP data
  shows upflows and downflows of ~ ± 3 km s<SUP>-1</SUP> in proximity
  of the δ spot polarity inversion line (PIL), and horizontal motions
  along the PIL of the order of ~1 km s<SUP>-1</SUP>. The results
  obtained from the SIR inversion of CRISP data also indicate that the
  transverse magnetic field in the brighter region separating the two
  opposite magnetic polarities of the δ spot is tilted about ~45°
  with respect to the PIL. Solar Dynamics Observatory/Helioseismic and
  Magnetic Imager observations confirm the presence of motions of ~
  ± 3 km s<SUP>-1</SUP> in proximity of the PIL, which were observed
  to last 15 hr. From the data analyzed, we conclude that the steady,
  persistent, and subsonic motions observed along the δ spot PIL can be
  interpreted as being due to Evershed flows occurring in the penumbral
  filaments that show a curved, wrapped configuration. The fluting of
  the penumbral filaments and their bending, continuously increased by
  the approaching motion of the negative umbra toward the positive one,
  give rise to the complex line-of-sight velocity maps that we observed.

---------------------------------------------------------
Title: Understanding Measurements Returned by the Helioseismic and
    Magnetic Imager
Authors: Cohen, Daniel Parke; Criscuoli, Serena
2014AAS...22412351C    Altcode:
  The Helioseismic and Magnetic Imager (HMI) aboard the Solar Dynamics
  Observatory (SDO) observes the Sun at the FeI 6173 Å line and returns
  full disk maps of line-of-sight observables including the magnetic
  field flux, FeI line width, line depth, and continuum intensity. To
  properly interpret such data it is important to understand any issues
  with the HMI and the pipeline that produces these observables. At this
  aim, HMI data were analyzed at both daily intervals for a span of 3
  years at disk center in the quiet Sun and hourly intervals for a span
  of 200 hours around an active region. Systematic effects attributed to
  issues with instrument adjustments and re-calibrations, variations in
  the transmission filters and the orbital velocities of the SDO were
  found while the actual physical evolutions of such observables were
  difficult to determine. Velocities and magnetic flux measurements are
  less affected, as the aforementioned effects are partially compensated
  for by the HMI algorithm; the other observables are instead affected
  by larger uncertainties. In order to model these uncertainties, the
  HMI pipeline was tested with synthetic spectra generated through
  various 1D atmosphere models with radiative transfer code (the RH
  code). It was found that HMI estimates of line width, line depth, and
  continuum intensity are highly dependent on the shape of the line,
  and therefore highly dependent on the line-of-sight angle and the
  magnetic field associated to the model. The best estimates are found
  for Quiet regions at disk center, for which the relative differences
  between theoretical and HMI algorithm values are 6-8% for line width,
  10-15% for line depth, and 0.1-0.2% for continuum intensity. In general,
  the relative difference between theoretical values and HMI estimates
  increases toward the limb and with the increase of the field; the
  HMI algorithm seems to fail in regions with fields larger than ~2000
  G. This work is carried out through the National Solar Observatory
  Research Experiences for Undergraduate (REU) site program, which
  is co-funded by the Department of Defense in partnership with the
  NSF REU Program. The National Solar Observatory is operated by the
  Association of Universities for Research in Astronomy, Inc. (AURA)
  under cooperative agreement with the National Science Foundation.

---------------------------------------------------------
Title: Interpretation of Solar Irradiance Monitor Measurements
    through Analysis of 3D MHD Simulations
Authors: Criscuoli, S.; Uitenbroek, H.
2014ApJ...788..151C    Altcode: 2014arXiv1404.4651C
  Measurements from the Spectral Irradiance Monitor (SIM) on board the
  Solar Radiation and Climate Experiment mission indicate that solar
  spectral irradiance at visible and IR wavelengths varies in counter
  phase with the solar activity cycle. The sign of these variations is not
  reproduced by most of the irradiance reconstruction techniques based on
  variations of surface magnetism employed so far, and it is not yet clear
  whether SIM calibration procedures need to be improved or if instead
  new physical mechanisms must be invoked to explain such variations. We
  employ three-dimensional magnetohydrodynamic simulations of the solar
  photosphere to investigate the dependence of solar radiance in SIM
  visible and IR spectral ranges on variations of the filling factor of
  surface magnetic fields. We find that the contribution of magnetic
  features to solar radiance is strongly dependent on the location on
  the disk of the features, which are negative close to disk center and
  positive toward the limb. If features are homogeneously distributed over
  a region around the equator (activity belt), then their contribution
  to irradiance is positive with respect to the contribution of HD
  snapshots, but decreases with the increase of their magnetic flux for
  average magnetic flux larger than 50 G in at least two of the visible
  and IR spectral bands monitored by SIM. Under the assumption that the
  50 G snapshots are representative of quiet-Sun regions, we thus find
  that the Spectral Irradiance can be in counter-phase with the solar
  magnetic activity cycle.

---------------------------------------------------------
Title: Interpretation of Solar Spectral Irradiance variations from
    analysis of 3D MHD simulations
Authors: Criscuoli, Serena
2014AAS...22432361C    Altcode:
  Recent measurements by SIM radiometers show that the solar irradiance
  varies in the Visible and IR bands in counterphase with the magnetic
  activity cycle. Such variations have been largely debated, as they
  do not agree with measurements obtained with other radiometers, while
  the majority of reconstruction techniques employed to reconstruct the
  total irradiance do not reproduce such signals. It is therefore yet
  not clear whether the SIM measurements are still not fully compensated
  for residual instrumental degradation, or if instead new physical
  phenomena must be invoked to explain such variations. A large part
  of reconstruction techniques employ semiempirical one-dimensional
  models. In this contribution I will explain the limitations of such
  models and why we expect a noticeable improvement of reconstructions
  obtained by 3-D magnetohydrodynamic simulations. I will also present
  some preliminary results obtained with the STAGGER simulations which
  indicate that solar irradiance in the Visible and IR bands might be in
  counterphase with the magnetic activity, as measured by SIM radiometers.

---------------------------------------------------------
Title: The statistical distribution of the magnetic-field strength
    in G-band bright points
Authors: Criscuoli, S.; Uitenbroek, H.
2014A&A...562L...1C    Altcode: 2013arXiv1312.2611C
  Context. G-band bright points are small-sized features characterized
  by high photometric contrast. Theoretical investigations indicate
  that these features have associated magnetic-field strengths of 1
  to 2 kG. Results from observations, however, lead to contradictory
  results, indicating magnetic fields of only kG strength in some and
  including hG strengths in others. <BR /> Aims: To understand the
  differences between measurements reported in the literature, and to
  reconcile them with results from theory, we analyzed the distribution
  of the magnetic-field strength of G-band bright features identified
  in synthetic images of the solar photosphere and its sensitivity
  to observational and methodological effects. <BR /> Methods: We
  investigated the dependence of magnetic-field strength distributions of
  G-band bright points identified in 3D magnetohydrodynamic simulations
  on feature selection method, data sampling, alignment, and spatial
  resolution. <BR /> Results: The distribution of the magnetic-field
  strength of G-band bright features shows two peaks, one at about 1.5
  kG and one below 1 hG. The former corresponds to magnetic features,
  the second mostly to bright granules. Peaks at several hG are obtained
  only on spatially degraded or misaligned data. <BR /> Conclusions:
  Simulations show that magnetic G-band bright points have typically
  associated field strengths of a few kG. Field strengths in the hG
  range can result from observational effects, which explains the
  discrepancies presented in the literature. Our results also indicate
  that results from spectro-polarimetric inversions with an imposed unit
  filling-factor should be employed with great caution.

---------------------------------------------------------
Title: Comparison of Physical Properties of Quiet and Active Regions
    Through the Analysis of Magnetohydrodynamic Simulations of the
    Solar Photosphere
Authors: Criscuoli, S.
2013ApJ...778...27C    Altcode: 2013arXiv1309.5494C
  Recent observations have shown that the photometric and dynamic
  properties of granulation and small-scale magnetic features depend on
  the amount of magnetic flux of the region they are embedded in. We
  analyze results from numerical hydrodynamic and magnetohydrodynamic
  simulations characterized by different amounts of average magnetic
  flux and find qualitatively the same differences as those reported
  from observations. We show that these different physical properties
  result from the inhibition of convection induced by the presence of
  the magnetic field, which changes the temperature stratification of
  both quiet and magnetic regions. Our results are relevant for solar
  irradiance variations studies, as such differences are still not
  properly taken into account in irradiance reconstruction models.

---------------------------------------------------------
Title: Effects of Unresolved Magnetic Field on Fe I 617.3 and 630.2
    nm Line Shapes
Authors: Criscuoli, S.; Ermolli, I.; Uitenbroek, H.; Giorgi, F.
2013ApJ...763..144C    Altcode: 2012arXiv1212.2190C
  The contribution of the quiet Sun to solar irradiance variability,
  either due to changes of the solar effective temperature or
  to the presence of unresolved magnetic field, is still poorly
  understood. In this study we investigate spectral line diagnostics
  that are sensitive to both temperature variations and the presence of
  small-scale unresolved magnetic features in these areas of the solar
  atmosphere. Specifically, we study the dependence on the magnetic flux
  density of three parameters describing the shape of two magnetically
  sensitive Fe I lines, at 630.2 nm and 617.3 nm, namely the line core
  intensity (IC), the FWHM, and the equivalent width (EQW). To this end
  we analyze observations of active region NOAA 11172, acquired with
  Interferometric Bidimensional Spectrometer at the Dunn Solar Telescope,
  as well as results from numerical synthesis. Our results show that IC
  is sensitive to both temperature and magnetic flux density variations,
  FWHM is mostly affected by magnetic field changes, and EQW is mostly
  sensitive to temperature. Variations of a few percent of the measured
  line parameters are found in observational data that were spatially
  degraded to represent quiet-Sun, disk-center, medium-resolution
  observations. It is therefore possible to disentangle magnetic from
  pure thermodynamic effects by the comparison of temporal variations
  of the EQW and the FWHM of either of the two Fe I lines.

---------------------------------------------------------
Title: A novel method to estimate temperature gradients in stellar
    photospheres.
Authors: Uitenbroek, H.; Criscuoli, S.
2013MmSAI..84..369U    Altcode:
  Inversions utilizing one-dimensional atmospheric models provide
  information about the thermal stratification of stars, but these
  models are in general not unique nor sufficiently descriptive of the
  physical conditions of a star. Here we propose a novel model-independent
  method to better constrain the temperature stratification in a stellar
  atmosphere. In our method we employ intensities measured at opacity
  conjugate wavelength pairs to improve the estimate of temperature
  stratification that is obtained from radiation temperatures in
  combination with the Eddington-Barbier relation. This relation can
  lead to significant errors because of the non-linear dependence of the
  source function on optical depth, even in the case of continua. Such
  errors are substantially reduced by combining observations at pairs of
  conjugate continua, which have the same H<SUP>-</SUP> opacity between
  them, and therefore pairwise form at the same height.

---------------------------------------------------------
Title: Small-scale brightenings observed in active regions with SST
    and Hinode
Authors: Cristaldi, A.; Guglielmino, S. L.; Zuccarello, F.; Ermolli,
   I.; Falco, M.; Criscuoli, S.
2013MmSAI..84..339C    Altcode:
  Ca II H brightenings are good proxies of transient phenomena occurring
  in the solar chromosphere. We analyze temporal series of Ca II H
  filtergrams taken with SST at extreme high resolution (0.15 arcsec)
  at different line positions, simultaneously with spectropolarimetric
  data in the Fe I pair at 630.2 nm and Hinode/SOT data, to study the
  interactions between flux systems. Ca II H core brightenings have
  been observed in areas surrounding the sunspot penumbra, following
  their evolution.

---------------------------------------------------------
Title: On the sensitivity of FeI 617.3 and 630.2 nm line shapes to
    unresolved magnetic fields
Authors: Criscuoli, S.; Ermolli, I.; Uitenbroek, H.; Giorgi, F.
2013MmSAI..84..335C    Altcode:
  Our study was aimed at obtaining line diagnostics sensitive to
  effects of small scale magnetic features that are unresolved in
  observations. We studied the dependence on the magnetic flux of
  parameters describing the two Fe I lines at 630.2 and 617.3 nm. In
  particular, we analyzed the line core intensity (IC), full width
  half maximum (FWHM), and equivalent width (EQW) of Stokes I in NOAA
  11172 observed with IBIS at the Dunn Solar Telescope on March 17th,
  2011. Our results show that IC is sensitive to both temperature and
  magnetic flux variations, while FWHM is sensitive mostly to magnetic
  flux variations. The EQW is almost insensitive to magnetic flux and
  mostly sensitive to temperature. Variations of a few percents of line
  parameters are found in data spatially degraded to represent quiet
  Sun, disk-centre conditions in medium resolution observations. Such
  variations can be observed with instruments as SOLIS/VSM, SDO/HMI,
  HINODE/SOT. Shapes of investigated lines can therefore be employed to
  investigate physical properties of quiet Sun regions, and in particular
  to disentangle magnetic and thermodynamic effects an d their variations
  over the magnetic cycle.

---------------------------------------------------------
Title: Sunspot evolution observed with SST.
Authors: Falco, M.; Zuccarello, F.; Criscuoli, S.; Cristaldi, A.;
   Guglielmino, S. L.; Ermolli, I.
2013MmSAI..84..345F    Altcode:
  We report on the evolution of an active region NOAA 11263 observed
  with SST at extreme high spatial resolution (0.15 arcsec). We analyzed
  spectral and spectropolarimetric data acquired at Fe I 557.6 nm and
  630.2 nm spectral ranges, respectively, to study the magnetic field
  properties and the dynamics of the plasma in the umbral and penumbral
  region of the sunspot. Interestingly, images acquired in photospheric
  continuum show twisting motions of the penumbral filaments. Moreover,
  we investigate if MMFs are present during the evolution of the
  sunspot. Brightenings in Ca II H line are also noticed, indicating
  the occurrence of transient phenomena in the chromosphere.

---------------------------------------------------------
Title: Spectro-polarimetric Observations of Moving Magnetic Features
    around a Pore
Authors: Zuccarello, F.; Berrilli, F.; Criscuoli, S.; Del Moro, D.;
   Ermolli, I.; Giannattasio, F.; Giorgi, F.; Romano, P.; Viticchiè, B.
2012ASPC..463...51Z    Altcode:
  Moving Magnetic Features (MMFs) are small-size magnetic elements that
  are seen to stream-out from sunspots. Although several observations
  suggest that MMFs are closely related to the existence and presence
  of penumbral filaments, there are some very few observations that
  report MMFs streaming from pores and sunspots after the penumbra has
  disappeared. Here we report on the first high spectral, spatial and
  temporal resolution observations of type II and III MMFs streaming out
  from a small pore and compare our results with previous observations of
  features streaming out from penumbrae. We analyzed spectro-polarimetric
  observations of NOAA 11005 acquired with the IBIS instrument at
  the Dunn Solar Telescope in the Fe I 617.3 nm and the Ca II 854.2 nm
  spectral lines, and in the G-band. We show that the characteristics of
  the investigated MMFs agree with those reported in the literature for
  MMFs which stream out from spots with penumbrae. We believe that our
  results provide new information that might be helpful in the future
  development and upgrade of numerical modeling of the generation of
  MMFs in the lack of a penumbra.

---------------------------------------------------------
Title: IBIS: High-Resolution Multi-Height Observations and Magnetic
    Field Retrieval
Authors: Del Moro, D. .; Berrilli, F.; Stangalini, M.; Giannattasio,
   F.; Piazzesi, R.; Giovannelli, L.; Viticchiè, B.; Vantaggiato, M.;
   Sobotka, M.; Jurčák, J.; Criscuoli, S.; Giorgi, F.; Zuccarello, F.
2012ASPC..463...33D    Altcode:
  IBIS (Interferometric BIdimensional Spectrometer) allows us to measure
  the four Stokes parameters in several spectroscopic lines with high
  spatial and spectral resolutions. With this information, we can
  retrieve both the dynamics and the magnetic field at different layers
  of the Photosphere and Chromosphere. The high spectral, spatial and
  temporal resolutions and the polarimetric sensitivity of IBIS allows
  us to study different phenomena taking place in the solar atmosphere
  with new tools. As an example, we highlight some applications of
  IBIS observations and analysis: <BR /> · Radiative and dynamical
  properties of Photospheric Bright Points versus their magnetic field
  concentration. <BR /> · Close up analysis of magnetic, velocity and
  temperature field in a solar pore. <BR /> · MHD wave propagation from
  the photosphere to the chromosphere in complex magnetic configuration.

---------------------------------------------------------
Title: High cadence spectropolarimetry of moving magnetic features
    observed around a pore
Authors: Criscuoli, S.; Del Moro, D.; Giannattasio, F.; Viticchié,
   B.; Giorgi, F.; Ermolli, I.; Zuccarello, F.; Berrilli, F.
2012A&A...546A..26C    Altcode: 2012arXiv1208.2039C
  Context. Moving magnetic features (MMFs) are small-size magnetic
  elements that are seen to stream out from sunspots, generally during
  their decay phase. Several observational results presented in the
  literature suggest them to be closely related to magnetic filaments
  that extend from the penumbra of the parent spot. Nevertheless,
  few observations of MMFs streaming out from spots without penumbra
  have been reported. The literature still lacks analyses of the
  physical properties of these features. <BR /> Aims: We investigate
  physical properties of monopolar MMFs observed around a small pore
  that had developed penumbra in the days preceding our observations
  and compare our results with those reported in the literature for
  features observed around sunspots. <BR /> Methods: We analyzed NOAA
  11005 during its decay phase with data acquired at the Dunn Solar
  Telescope in the Fe i 617.3 nm and the Ca ii 854.2 nm spectral lines
  with IBIS, and in the G-band. The field of view showed monopolar
  MMFs of both polarities streaming out from the leading negative
  polarity pore of the observed active region. Combining different
  analyses of the data, we investigated the temporal evolution of the
  relevant physical quantities associated with the MMFs as well as the
  photospheric and chromospheric signatures of these features. <BR />
  Results: We show that the characteristics of the investigated MMFs
  agree with those reported in the literature for MMFs that stream out
  from spots with penumbrae. Moreover, observations of at least two of the
  observed features suggest them to be manifestations of emerging magnetic
  arches. <P />Appendices A and B, and a movie are available in electronic
  form at <A href="http://www.aanda.org">http://www.aanda.org</A>

---------------------------------------------------------
Title: A Comparative Analysis of Photospheric Bright Points in an
    Active Region and in the Quiet Sun
Authors: Romano, P.; Berrilli, F.; Criscuoli, S.; Del Moro, D.;
   Ermolli, I.; Giorgi, F.; Viticchié, B.; Zuccarello, F.
2012SoPh..280..407R    Altcode: 2012SoPh..tmp...26R
  We present a comparative study of photometric and dynamic properties
  of photospheric bright points (BPs) observed at the disk centre in
  the active region (AR) NOAA 10912 and in the quiet Sun. We found that
  the average concentration of BPs is 54% larger in the AR than in the
  quiet Sun. We also measure a decrease of the BP concentration and an
  increase of their size moving away from the AR centre. However, these
  variations can be ascribed to the variation of the spatial resolution
  and image quality in the field of view of the AR dataset. We also found
  that BPs in the quiet Sun are associated with larger downflow motions
  than those measured within the AR. Finally, from our measurements of
  contrast and velocity along the line of sight, we deduced that BPs
  are less bright in high magnetic flux density regions than in quiet
  regions, due to a lower efficiency of convection in the former regions.

---------------------------------------------------------
Title: Physical properties of Moving Magnetic Features observed
    around a pore
Authors: Criscuoli, S.; Del Moro, D.; Giannattasio, F.; Viticchié,
   B.; Giorgi, F.; Ermolli, I.; Zuccarello, F.; Berrilli, F.
2012EAS....55...87C    Altcode:
  Movies of magnetograms of sunspots often show small-size magnetic
  patches that move radially away and seem to be expelled from the
  field of the spot. These patches are named Moving Magnetic Features
  (MMFs). They have been mostly observed around spots and have been
  interpreted as manifestations of penumbral filaments. Nevertheless,
  few observations of MMFS streaming out from spots without penumbra
  have been reported. He we investigate the physical properties of MMFs
  observed around the field of a pore derived by the analyses of high
  spectral, spatial and temporal resolution data acquired at the Dunn
  Solar Telescope with IBIS. We find that the main properties of the
  investigated features agree with those reported for MMFs observed
  around regular spots. These results indicate that an improvement of
  current numerical simulations is required to understand the generation
  of MMFs in the lack of penumbrae.

---------------------------------------------------------
Title: Properties of G-band Bright Points  derived from IBIS
    observations
Authors: Criscuoli, S.; Del Moro, D.; Giorgi, F.; Romano, P.; Berrilli,
   F.; Ermolli, I.; Viticchié, B.; Zuccarello, F.
2012MSAIS..19...93C    Altcode: 2010arXiv1011.4890C
  We have investigated properties of photospheric Bright Points (BPs)
  observed in an Active Region during its decay phase and in a quiet Sun
  region. We have analyzed two sets of photospheric observations taken
  with IBIS (Interferometric Bidimensioal Spectrometer) at the NSO Dunn
  Solar Telescope. The first set consists of spectral data acquired in the
  Fe I 709.0 nm and Ca I 854.2 nm lines and simultaneous broad-band and
  of G-band observations. The second set consists of spectro-polarimetric
  observations in the Fe I 630.15 nm - 630.25 nm doublet and simultaneous
  white light and G-band observations. <P />The relation between BP
  filling factor and RMS image contrast indicates that, on average,
  BPs cover up to 3% of the solar surface outside Active Regions. The
  relation between area and intensity values of the features identified
  on both data sets suggests that they are composed of aggregations of
  magnetic flux elements. The horizontal velocity values are as high
  as 2 km/s, thus supporting the scenario of BPs motion contributing to
  the coronal heating.

---------------------------------------------------------
Title: Recent results from optical synoptic observations of the
    solar atmosphere with ground-based instruments
Authors: Ermolli, I.; Criscuoli, S.; Giorgi, F.
2011CoSka..41...73E    Altcode:
  This brief review summarizes three research topics recently addressed
  with synoptic observations carried out at the Ca II K line and other
  continuum spectral ranges and relating to solar variability occurring
  on time scales from a day to a few decades. Namely, the irradiance
  reconstructions from intensity images, the radiative emission of solar
  features in the Ca II K line, and the comparison of time series of Ca
  II K spectroheliograms.

---------------------------------------------------------
Title: Why One-dimensional Models Fail in the Diagnosis of Average
    Spectra from Inhomogeneous Stellar Atmospheres
Authors: Uitenbroek, Han; Criscuoli, Serena
2011ApJ...736...69U    Altcode: 2011arXiv1101.2643U
  We investigate the feasibility of representing a structured
  multi-dimensional stellar atmosphere with a single one-dimensional
  average stratification for the purpose of spectral diagnosis of the
  atmosphere's average spectrum. In particular, we construct four
  different one-dimensional stratifications from a single snapshot
  of a magnetohydrodynamic simulation of solar convection: one by
  averaging its properties over surfaces of constant height and three
  by averaging over surfaces of constant optical depth at 500 nm. Using
  these models, we calculate continuum and atomic and molecular line
  intensities and their center-to-limb variations. From an analysis of
  the emerging spectra, we identify three main reasons why these average
  representations are inadequate for accurate determination of stellar
  atmospheric properties through spectroscopic analysis. These reasons are
  nonlinearity in the Planck function with temperature, which raises the
  average emergent intensity of an inhomogeneous atmosphere above that of
  an average-property atmosphere, even if their temperature-optical depth
  stratification is identical; nonlinearities in molecular formation with
  temperature and density, which raise the abundance of molecules of an
  inhomogeneous atmosphere over that in a one-dimensional model with the
  same average properties; and the anisotropy of convective motions,
  which strongly affects the center-to-limb variation of line-core
  intensities. We argue therefore that a one-dimensional atmospheric
  model that reproduces the mean spectrum of an inhomogeneous atmosphere
  necessarily does not reflect the average physical properties of that
  atmosphere and is therefore inherently unreliable.

---------------------------------------------------------
Title: Evolution of Small-scale Magnetic Features Streaming-out from
    a Pore
Authors: Criscuoli, S.; Del Moro, D.; Romano, P.; Berrilli, F.;
Ermolli, I. : Giorgi, F.; Vitichhié, B.; Zuccarello, F.
2011ASPC..437..493C    Altcode:
  We present results from observations of Moving Magnetic Features
  (MMFs) of different types observed on region NOAA 11005. The analyses
  is based on spectro-polarimetric data obtained with the Interferometric
  Bidimensional Spectrometer (IBIS) at various spectral ranges. We present
  new evidences of bipolar MMFs observed to stream out from pores and
  show the temporal evolution of magnetic, dynamic and morphological
  properties of these features.

---------------------------------------------------------
Title: Line Shape Effects on Intensity Measurements of Solar Features:
    Brightness Correction to SOHO MDI Continuum Images
Authors: Criscuoli, S.; Ermolli, I.; Del Moro, D.; Giorgi, F.;
   Tritschler, A.; Uitenbroek, H.; Vitas, N.
2011ApJ...728...92C    Altcode: 2010arXiv1012.2561C
  Continuum intensity observations obtained with the Michelson
  Doppler Imager (MDI) on board the SOHO mission provide long time
  series of filtergrams that are ideal for studying the evolution of
  large-scale phenomena in the solar atmosphere and their dependence on
  solar activity. These filtergrams, however, are not taken in a pure
  continuum spectral band, but are constructed from a proxy, namely a
  combination of filtergrams sampling the Ni I 6768 Å line. We studied
  the sensitivity of this continuum proxy to the shape of the nickel line
  and to the degradation in the instrumental transmission profiles. We
  compared continuum intensity measurements near the nickel line with
  MDI proxy values in three sets of high-resolution spectro-polarimetric
  data obtained with the Interferometric Bidimensional Spectrometer,
  and in synthetic data, obtained from multi-dimensional simulations of
  magneto-convection and one-dimensional atmosphere models. We found that
  MDI continuum measurements require brightness corrections which depend
  on magnetic field strength, temperature and, to a smaller extent, plasma
  velocity. The correction ranges from 2% to 25% in sunspots, and is,
  on average, less than 2% for other features. The brightness correction
  also varies with position on the disk, with larger variations obtained
  for sunspots, and smaller variations obtained for quiet Sun, faculae,
  and micropores. Correction factors derived from observations agree
  with those deduced from the numerical simulations when observational
  effects are taken into account. Finally, we found that the investigated
  potential uncertainties in the transmission characteristics of MDI
  filters only slightly affect the brightness correction to proxy
  measurements.

---------------------------------------------------------
Title: Imaging Spectropolarimetry with IBIS. II. On the Fine Structure
    of G-band Bright Features
Authors: Viticchié, B.; Del Moro, D.; Criscuoli, S.; Berrilli, F.
2010ApJ...723..787V    Altcode: 2010arXiv1009.0721V
  We present new results from first observations of the quiet solar
  photosphere performed through the Interferometric BIdimensional
  Spectrometer (IBIS) in spectropolarimetric mode. IBIS allowed us to
  measure the four Stokes parameters in the Fe I 630.15 nm and Fe I
  630.25 nm lines with high spatial and spectral resolutions for 53
  minutes; the polarimetric sensitivity achieved by the instrument is
  3 × 10<SUP>-3</SUP> the continuum intensity level. We focus on the
  correlation which emerges between the G-band bright feature brightness
  and magnetic filling factor of ~10<SUP>3</SUP> G (kG) fields derived
  by inverting the Stokes I and V profiles. In more detail, we present
  the correlation first in a pixel-by-pixel study of a sime3” wide
  bright feature (a small network patch) and then we show that such a
  result can be extended to all the bright features found in the data
  set at any instant of the time sequence. The higher the kilo-Gauss
  filling factor associated to a feature, the higher the brightness of
  the feature itself. Filling factors up to sime35% are obtained for
  the brightest features. Considering the values of the filling factors
  derived from the inversion analysis of spectropolarimetric data and the
  brightness variation observed in the G-band data we put forward an upper
  limit for the smallest scale over which magnetic flux concentrations
  in intergranular lanes produce a G-band brightness enhancement
  (sime0farcs1). Moreover, the brightness saturation observed for feature
  sizes comparable to the resolution of the observations is compatible
  with the large G-band bright features being clusters of sub-arcsecond
  bright points. This conclusion deserves to be confirmed by forthcoming
  spectropolarimetric observations at higher spatial resolution.

---------------------------------------------------------
Title: Radiative emission of solar features in the Ca II K line:
    comparison of measurements and models
Authors: Ermolli, I.; Criscuoli, S.; Uitenbroek, H.; Giorgi, F.;
   Rast, M. P.; Solanki, S. K.
2010A&A...523A..55E    Altcode: 2010arXiv1009.0227E
  Context. The intensity of the Ca II K resonance line observed with
  spectrographs and Lyot-type filters has long served as a diagnostic of
  the solar chromosphere. However, the literature contains a relative
  lack of photometric measurements of solar features observed at this
  spectral range. <BR /> Aims: We study the radiative emission of various
  types of solar features, such as quiet Sun, enhanced network, plage,
  and bright plage regions, identified on filtergrams taken in the Ca II
  K line. <BR /> Methods: We analysed full-disk images obtained with the
  PSPT, by using three interference filters that sample the Ca II K line
  with different bandpasses. We studied the dependence of the radiative
  emission of disk features on the filter bandpass. We also performed a
  non-local thermal equilibrium (NLTE) spectral synthesis of the Ca II
  K line integrated over the bandpass of PSPT filters. The synthesis
  was carried out by utilizing the partial frequency redistribution
  (PRD) with the most recent set of semi-empirical atmosphere models
  in the literature and some earlier atmosphere models. As the studied
  models were computed by assuming the complete redistribution formalism
  (CRD), we also performed simulations with this approximation for
  comparison. <BR /> Results: We measured the center-to-limb variation
  of intensity values for various solar features identified on PSPT
  images and compared the results obtained with those derived from the
  synthesis. We find that CRD calculations derived using the most recent
  quiet Sun model, on average, reproduce the measured values of the
  quiet Sun regions slightly more accurately than PRD computations with
  the same model. This may reflect that the utilized atmospheric model
  was computed assuming CRD. Calculations with PRD on earlier quiet Sun
  model atmospheres reproduce measured quantities with a similar accuracy
  as to that achieved here by applying CRD to the recent model. We
  also find that the median contrast values measured for most of the
  identified bright features, disk positions, and filter bandpasses
  are, on average, a factor ≈1.9 lower than those derived from PRD
  simulations performed using the recent bright feature models. The
  discrepancy between measured and modeled values decreases by ≈12%
  after taking into account straylight effects on PSPT images. When
  moving towards the limb, PRD computations display closer agreement with
  the data than performed in CRD. Moreover, PRD computations on either
  the most recent or the earlier atmosphere models of bright features
  reproduce measurements from plage and bright plage regions with a
  similar accuracy. <P />Appendix A is only available in electronic form
  at <A href="http://www.aanda.org">http://www.aanda.org</A>

---------------------------------------------------------
Title: A decline and fall in the future of Italian Astronomy?
Authors: Antonelli, Angelo; Antonuccio-Delogu, Vincenzo; Baruffolo,
   Andrea; Benetti, Stefano; Bianchi, Simone; Biviano, Andrea; Bonafede,
   Annalisa; Bondi, Marco; Borgani, Stefano; Bragaglia, Angela; Brescia,
   Massimo; Brucato, John Robert; Brunetti, Gianfranco; Brunino, Riccardo;
   Cantiello, Michele; Casasola, Viviana; Cassano, Rossella; Cellino,
   Alberto; Cescutti, Gabriele; Cimatti, Andrea; Comastri, Andrea;
   Corbelli, Edvige; Cresci, Giovanni; Criscuoli, Serena; Cristiani,
   Stefano; Cupani, Guido; De Grandi, Sabrina; D'Elia, Valerio; Del
   Santo, Melania; De Lucia, Gabriella; Desidera, Silvano; Di Criscienzo,
   Marcella; D'Odorico, Valentina; Dotto, Elisabetta; Fontanot, Fabio;
   Gai, Mario; Gallerani, Simona; Gallozzi, Stefano; Garilli, Bianca;
   Gioia, Isabella; Girardi, Marisa; Gitti, Myriam; Granato, Gianluigi;
   Gratton, Raffaele; Grazian, Andrea; Gruppioni, Carlotta; Hunt, Leslie;
   Leto, Giuseppe; Israel, Gianluca; Magliocchetti, Manuela; Magrini,
   Laura; Mainetti, Gabriele; Mannucci, Filippo; Marconi, Alessandro;
   Marelli, Martino; Maris, Michele; Matteucci, Francesca; Meneghetti,
   Massimo; Mennella, Aniello; Mercurio, Amata; Molendi, Silvano; Monaco,
   Pierluigi; Moretti, Alessia; Murante, Giuseppe; Nicastro, Fabrizio;
   Orio, Marina; Paizis, Adamantia; Panessa, Francesca; Pasian, Fabio;
   Pentericci, Laura; Pozzetti, Lucia; Rossetti, Mariachiara; Santos,
   Joana S.; Saro, Alexandro; Schneider, Raffaella; Silva, Laura;
   Silvotti, Roberto; Smart, Richard; Tiengo, Andrea; Tornatore, Luca;
   Tozzi, Paolo; Trussoni, Edoardo; Valentinuzzi, Tiziano; Vanzella, Eros;
   Vazza, Franco; Vecchiato, Alberto; Venturi, Tiziana; Vianello, Giacomo;
   Viel, Matteo; Villalobos, Alvaro; Viotto, Valentina; Vulcani, Benedetta
2010arXiv1007.1455A    Altcode:
  On May 27th 2010, the Italian astronomical community learned with
  concern that the National Institute for Astrophysics (INAF) was going
  to be suppressed, and that its employees were going to be transferred to
  the National Research Council (CNR). It was not clear if this applied to
  all employees (i.e. also to researchers hired on short-term contracts),
  and how this was going to happen in practice. In this letter, we give
  a brief historical overview of INAF and present a short chronicle of
  the few eventful days that followed. Starting from this example, we
  then comment on the current situation and prospects of astronomical
  research in Italy.

---------------------------------------------------------
Title: Radiative emission of solar features in Ca II K
Authors: Criscuoli, S.; Ermolli, I.; Fontenla, J.; Giorgi, F.; Rast,
   M.; Solanki, S. K.; Uitenbroek, H.
2010MmSAI..81..773C    Altcode: 2010arXiv1002.0244C
  We investigated the radiative emission of different types of solar
  features in the spectral range of the Ca II K line. We analyzed
  full-disk 2k × 2k observations from the Precision Solar Photometric
  Telescope (PSPT). The data were obtained by using three narrow-band
  interference filters that sample the Ca II K line with different pass
  bands. Two filters are centered in the line core, the other in the red
  wing of the line. We measured the intensity and contrast of various
  solar features, specifically quiet Sun (inter-network), network,
  enhanced network, plage, and bright plage (facula) regions. Moreover,
  we compared the results obtained with those derived from the numerical
  synthesis performed for the three PSPT filters with a widely used
  radiative code on a set of reference semi-empirical atmosphere models.

---------------------------------------------------------
Title: Magnetic evolution of superactive regions. Complexity and
    potentially unstable magnetic discontinuities
Authors: Criscuoli, S.; Romano, P.; Giorgi, F.; Zuccarello, F.
2009A&A...506.1429C    Altcode: 2009arXiv0908.3608C
  Context: It is widely accepted that solar flares are manifestations
  of magnetic reconnection events taking place in the solar
  atmosphere. Several aspects of these events remain unclear, although
  many efforts have been devoted to the investigation of magnetic
  field configurations at flare occurrence sites. <BR />Aims: In this
  work, we have studied the temporal evolution of some properties of
  a sample of superactive regions with the aim to single out the most
  significant for flare activity forecasting. <BR />Methods: We have
  investigated properties of 14 superactive regions, observed between
  January 1st 2000 and December 31st 2006 with MDI/SOHO instrument and
  characterized by a particularly intense flare activity during their
  passage on the solar disk. We have analyzed the temporal evolution of
  fractal and multifractal properties of photospheric magnetic fields,
  namely the generalized fractal dimension and the contribution and
  dimensional diversities, which describe geometrical properties of
  the magnetic field, as well as the potential unstable volumes of
  magnetic discontinuities above the studied ARs, which may provide
  information about the magnetic field configuration in upper layers of
  the atmosphere. Correlations of these quantities with the flare index,
  which provides information about the flare activity of a region, have
  also been estimated. <BR />Results: We found that in 50% of our sample
  the generalized fractal dimension is correlated with the flare index
  computed over windows of 50 h, while the contribution diversity and the
  dimensional diversity are anticorrelated with the same index. A clear
  increase of the potential unstable volume of magnetic discontinuities in
  the corona is observed before the phases characterized by more frequent
  and intense flares. We also found that the free energy distribution
  functions of unstable volumes of the analyzed superactive regions can be
  fitted with straight lines whose slope is larger than the values found
  in previous works for less active magnetic regions. <BR />Conclusions:
  The generalized fractal dimension and the potential unstable volume
  of magnetic discontinuities are the most suitable for statistical
  investigations of relations with flare activity over longer (50 h)
  and shorter (few hours) time intervals, respectively. <P />Appendix
  A is only available in electronic form at http://www.aanda.org

---------------------------------------------------------
Title: Observation of bipolar moving magnetic features streaming
    out from a naked spot
Authors: Zuccarello, F.; Romano, P.; Guglielmino, S. L.; Centrone,
   M.; Criscuoli, S.; Ermolli, I.; Berrilli, F.; Del Moro, D.
2009A&A...500L...5Z    Altcode:
  Context: Mechanisms responsible for active-region formation, evolution,
  and decay have been investigated by many authors and several common
  features have been identified. In particular, a key element in the
  dispersal of the magnetic field seems to be the presence of magnetic
  elements, called moving magnetic features (MMFs). <BR />Aims: We
  analyze the short-lived sunspot group NOAA 10977, which appeared on
  the solar disk between 2 and 8 December 2007, to study the details of
  its emergence and decay phases. <BR />Methods: We performed a multi
  wavelength analysis of the region using images at visible (G band
  and Hα) and near-IR (Ca II) wavelengths acquired by both the IBIS
  instrument and SOT/HINODE, EUV images (17.1 nm) acquired by TRACE, and
  MDI and SOT magnetograms. <BR />Results: The observed region exhibits
  some peculiarities. During the emergence phase the formation of the
  f-pore was initially observed, while the p-polarity later formed a
  naked spot, i.e., a sunspot without a penumbra. We measured a moat
  flow around this spot, and observed some MMFs streaming out from it
  during the decay phase. The characteristics of these MMFs allowed us
  to classify them as type I (U-shaped) MMFs. They were also cospatial
  with sites of increased brightness both in the photosphere and the
  chromosphere. <BR />Conclusions: The presence of bipolar MMFs in a
  naked spot indicates that current interpretation of bipolar MMFs,
  as extensions of the penumbral filaments beyond the sunspot outer
  boundaries, should be revised, to take into account this observational
  evidence. We believe that our results provide new insights into
  improving models of sunspot evolution.

---------------------------------------------------------
Title: Photometric Properties of Magnetic Elements: Resolved and
    Unresolved Features
Authors: Criscuoli, S.
2009ASPC..405..303C    Altcode:
  We investigate, by numerical simulations, the photometric signature of
  magnetic flux tubes in the solar photosphere. We show that the observed
  contrast profiles are determined not only by the physical properties
  of the tube and its surroundings, but also by the peculiarities of the
  observations, including the line/continuum formation height and the
  spatial resolution. The aim is to understand these contributions well
  enough so that multi-wavelength observations can begin to disentangle
  them.

---------------------------------------------------------
Title: The digitized archive of the Arcetri
    spectroheliograms. Preliminary results from the analysis of Ca II
    K images
Authors: Ermolli, I.; Marchei, E.; Centrone, M.; Criscuoli, S.;
   Giorgi, F.; Perna, C.
2009A&A...499..627E    Altcode:
  Context: The increasing interest in the recovery of historic data and
  the availability of new hardware resources is leading to projects to
  digitize photographic archives of astronomical observations. In addition
  to preservation, solar archives are digitized because the observations
  stored in such archives have the potential of providing unique
  information about solar magnetism, which can improve knowledge about
  long-term solar changes. <BR />Aims: The solar tower of the Arcetri
  Astrophysical Observatory produced synoptic observations of the solar
  atmosphere from 1926 to 1974. The photographic archive contains about
  13 000 plates of full-disk Ca II K and Hα spectroheliograms acquired
  during about 5000 observing days. The program for the digitization and
  distribution of the images of this archive was carried out at the Rome
  Astronomical Observatory and is now complete. <BR />Methods: Nearly 13
  000 plates were scanned with a commercial device and stored on DVD, as
  well as in a database accessible online. Image processing was developed
  for the reduction of the data and their photographic calibration. <BR
  />Results: The obtained digital archive provides the astronomical
  community with the Arcetri historical solar observations and with
  measurements of solar features identified in such observations. As
  an example, we show some preliminary results concerning the temporal
  variability of facular regions identified in the time-series of Ca
  II K observations. <BR />Conclusions: Existing programs studying
  solar activity and variability, as well as new scientific projects,
  will benefit from the Arcetri digital archive, since it extends the
  temporal baseline of digital full-disk solar observations, and it
  provides data for the inter-calibration of results obtained from
  measurements performed in similar observations.

---------------------------------------------------------
Title: Photometric properties of resolved and unresolved magnetic
    elements
Authors: Criscuoli, S.; Rast, M. P.
2009A&A...495..621C    Altcode: 2008arXiv0812.1727C
  Aims: We investigate the photometric signature of magnetic flux tubes
  in the solar photosphere. <BR />Methods: We developed two-dimensional,
  static numerical models of isolated and clustered magnetic flux
  tubes. We investigated the emergent intensity profiles at different
  lines-of-sight for various spatial resolutions and opacity models. <BR
  />Results: We found that both geometric and photometric properties
  of bright magnetic features are determined not only by the physical
  properties of the tube and its surroundings, but also by the
  particularities of the observations, including the line/continuum
  formation height, the spatial resolution, and the image analysis
  techniques applied. We show that some observational results presented
  in the literature can be interpreted by considering bright magnetic
  features to be clusters of smaller elements, rather than a monolithic
  flux tube.

---------------------------------------------------------
Title: Enhancing the spatial resolution of IBIS spectrograms via
    Multi-Frame Blind Deconvolution.
Authors: Del Moro, D.; Centrone, M.; Giorgi, F.; Criscuoli, S.
2009MmSAI..80..270D    Altcode:
  We compare the spatial resolution between observed and restored
  spectrographs of the solar photosphere, acquired with IBIS
  (Interferometric BIdimensional Spectrometer) currently feeded by
  the HOAO (High-Order Adaptive Optics) channel of the DST (Dunn Solar
  Telescope). The observations consist of 3×120 sequences, containing
  a 25 images scan of the NiI 676.8 nm line, a 15 images scan of the FeI
  709.0 nm line and a 13 images scan of the CaI 854.2 nm line. For each
  spectral image a broadband (661± 5 nm) and a G-band (430.5 ± 1 nm)
  counterpart were acquired simultaneously. The images were successively
  restored via the MFBD (Multi-Frame Blind Deconvolution) procedure to
  achieve near diffraction limit resolution in the whole FOV for the
  whole dataset duration.

---------------------------------------------------------
Title: Studying the decay phase of a short-lived active region
    with coordinated DST/IBIS, Hinode/EIS+SOT+XRT, SOHO/MDI and TRACE
    observations
Authors: Zuccarello, F.; Berrilli, F.; Centrone, M.; Contarino, L.;
   Criscuoli, S.; Del Moro, D.; Ermolli, I.; Giorgi, F.; Guglielmino,
   L. S.; Salerno, C.; Spadaro, D.; Romano, P.
2008ESPM...12.2.56Z    Altcode:
  This study concerns the physical processes occurring during the decay
  phase of the short-lived active region NOAA 10977, as evaluated from
  analysis of data gathered using ground- (DST/IBIS) and space-based
  (Hinode/EIS+SOT+XRT, SOHO/MDI and TRACE) facilities. The coordinated
  observing campaign was performed from December 1st to 9th, 2007,
  covering several spectral ranges, with unprecedented spatial and
  spectral resolution. We present preliminary results of the Doppler
  analysis of plasma motions evaluated from monochromatic images taken
  along the Ca II (8542 Å) and the Fe I (7049 Å) spectral lines with
  IBIS. We also report results concerning the horizontal displacements of
  photospheric magnetic structures and advection flows as obtained from
  application of Local Correlation Tracking (LCT) and Two-Level Structure
  Tracking (TST) techniques to both the LoS magnetograms taken by MDI
  and to high resolution intensity maps obtained by IBIS at DST/NSO. <P
  />Further contributions to understanding the mechanisms at the base
  of the magnetic field diffusion are provided from the inversion of
  the Stokes profiles of the photospheric Fe I lines at 6301.5 Å and
  6302.5 Å, obtained with SOT/SP, and the analysis of filtergrams in
  the core of the Ca II H line (3968.5 ± 3 Å) and images in G-band
  (4305 ± 8 Å) taken by SOT/BFI, as well as EIS data and images taken
  by the thin Be of XRT, and by TRACE at 171 Å and 1600 Å.

---------------------------------------------------------
Title: Temporal Evolution of Magnetic Properties of Super Active
    Regions
Authors: Criscuoli, S.; Giorgi, F.; Romano, P.; Zuccarello, F.
2008ESPM...12.2.57C    Altcode:
  It is widely accepted that solar flares are manifestations of magnetic
  reconnection events taking place in the solar atmosphere. Several
  aspects of these events remain unclear, although many efforts have
  been devoted to the investigation of magnetic field configurations at
  flares occurrence. <P />In this work we investigate some properties of
  26 super active regions, observed between Jan 1 2000 and Dec 31 2006
  with MDI/SOHO instrument and characterized by a particularly intense
  flare activity during their passage on the solar disc. We analyzed
  the temporal evolution of some fractal and multifractal estimators, as
  well as other parameters like the distorsion of the magnetic inversion
  line and the number of the singular points in potential fields with
  the aim to single out the most significant for flare forecasting.

---------------------------------------------------------
Title: Radiative Properties of Magnetic Elements at the Spectral
    Range of the Ni I 676.8 nm Line
Authors: Ermolli, I.; Centrone, M.; Criscuoli, S.; Giorgi, F.;
   Berrilli, F.; Del Moro, D.
2008ESPM...12.2.48E    Altcode:
  We present measurements of the radiative properties of magnetic
  elements at some spectral ranges, including the NiI 676.8 nm line. This
  mid-photospheric absorption line is used to derive the continuum
  intensity data and helioseismic measurements provided by the MDI and
  GONG instruments, respectively. We show the results obtained from the
  analysis of high resolution spatial and spectral measurement of two
  magnetic regions observed on November 2007 at DST/IBIS. We investigate
  the line profile changes in presence of magnetic field. We quantify
  the effects of such changes in the continuum intensity derived by
  SOI/MDI measurements.

---------------------------------------------------------
Title: Stray-light restoration of full-disk CaII K solar observations:
    a case study
Authors: Criscuoli, S.; Ermolli, I.
2008A&A...484..591C    Altcode: 2008arXiv0804.1010C
  Aims: We investigate whether restoration techniques, such as those
  developed for application to current observations, can be used to
  remove stray-light degradation effects on archive CaII K full-disk
  observations. We analyze to what extent these techniques can recover
  homogeneous time series of data. <BR />Methods: We develop a restoration
  algorithm based on a method presented by Walton &amp; Preminger (1999,
  ApJ, 514, 959). We apply this algorithm to data for both present-day
  and archive CaII K full-disk observations, which were acquired using
  the PSPT mounted at the Rome Observatory, or obtained by digitization
  of Mt Wilson photographic-archive spectroheliograms. <BR />Results: We
  show that the restoring algorithm improves both spatial resolution and
  photometric contrast of the analyzed solar observations. We find that
  the improvement in spatial resolution is similar for analyzed recent
  and archive data. On the other hand, the improvement of photometric
  contrast is quite poor for the archive data, with respect to the
  one obtained for the present-day images. We show that the quality of
  restored archive data depends on the photographic calibration applied to
  the original observations. In particular, photometry can be recovered
  with a restoring algorithm if the photographic-calibration preserves
  the intensity information stored in the original data, principally
  outside the solar-disk observations.

---------------------------------------------------------
Title: Photometric properties of magnetic elements: resolved and
    unresolved features
Authors: Criscuoli, Serena
2007arXiv0712.3294C    Altcode:
  We investigate, by numerical simulations, the photometric signature of
  magnetic flux tubes in the solar photosphere. We show that the observed
  contrast profiles are determined not only by the physical properties
  of the tube and its surroundings, but also by the peculiarities of
  the observations, including the line/continuum formation height and
  the spatial and spectral resolution. The aim is to understand these
  contributions well enough so that multi-wavelength observations can
  begin to disentangle them.

---------------------------------------------------------
Title: Photometric properties of facular features over the activity
    cycle
Authors: Ermolli, I.; Criscuoli, S.; Centrone, M.; Giorgi, F.;
   Penza, V.
2007A&A...465..305E    Altcode:
  Aims:We have analyzed the contrast of facular features identified
  in a large dataset of PSPT full-disk photometric images and SoHO/MDI
  magnetograms, obtained from 1998 to 2005. The aim of this work is to
  contribute to the improvement of semi-empirical atmospheric models
  and of irradiance studies and to understand the reasons for the
  controversial results of facular contrast already presented in the
  literature. <BR />Methods: We used different identification methods
  to analyze their effects upon the results obtained. We also analyzed
  the effects of the limited information content in the analyzed
  images. <BR />Results: We show that selection effects associated
  with the identification method may produce significant differences
  in the results. The facular contrast is not only a function of both
  selection methods and the heliocentric angle, but also of feature size,
  activity level, and content of the analyzed images. Comparisons of the
  results obtained with computations of the most recent semi-empirical
  atmospheric models of facular features show that these models reproduce
  limb-angle corrected contrast measurements with an offset up to ≈1%
  from the disk center to μ = 0.3.

---------------------------------------------------------
Title: Photometric Properties Of Complex Magnetic Elements In The
    Solar Photosphere
Authors: Criscuoli, Serena
2007PhDT.......314C    Altcode:
  In this thesis I investigate the photometric and geometric properties
  of bright magnetic features in the lower solar atmosphere. The
  contribution of these features to Total Solar Irradiance (TSI here
  after) variations observed at different temporal scales has been broadly
  showed during the last years. Nevertheless, measurements and theoretical
  investigations of their properties, on which reconstructions of TSI
  variations are based, have produced discrepant results. In order to
  interpret discrepancies presented in the literature and to improve
  our understanding of physical properties of magnetic elements, both
  experimental and theoretical aspects have been investigated. In the
  first part of the thesis I show results obtained by the analysis
  of full disk PSPT broad band images from Rome and Hawaii. Geometric
  properties and the possible connection with photometric properties
  have been investigated through the measurement of fractal dimension
  of features observed in chromosphere. Results I obtain agree very well
  with the ones presented in the literature carried out on similar data
  and with the same fractal dimension estimator. The fractal dimension
  increases in fact with features area and reaches a plateau at areas
  larger than about 1000-2000 Mm2. Nevertheless, by the analyses of images
  of fractals whose dimension is known by the theory, I show that fractal
  dimension estimation is critically effected by pixelization, technique
  employed to select magnetic structures on images and resolution. In
  particular the increase of fractal dimension with object size is an
  effect of pixelization and thus some conclusions previously drawn
  in the literature should be revisited. Photometric properties are
  investigated by the analyses of contrast of identified features in two
  photospheric bands and in the chromosphere. In particular the variation
  of the contrast with position on the solar disk and with object size
  is investigated. I show that the contrast in the chromosphere is not
  dependent on disk position and that in the photosphere monotonically
  increases from the center toward the limb. A comparison with previously
  published results shows a better agreement with authors that employed
  an identification methods similar to the ones I employed to select
  magnetic features on images. The contrast, especially at the limb,
  is also critically affected by seeing. Comparison of the scaling of
  average and maximum contrast with object size suggests that the smaller
  magnetic elements, whose clustering forms the features analyzed,
  are characterized by different photometric properties. The increase
  of average contrast with object size, very similar to the increase
  observed for the fractal dimension, is instead an effect of filling
  factor. In order to investigate the physical origin of the results
  and validate some of the conclusions drawn, 2D numerical codes based
  on the magnetic flux tube model have been developed. Plane parallel
  gray atmosphere in LTE is supposed and radiative and convective energy
  transport mechanisms have been taken into account. In particular two
  classes of models are investigated. In the first one convection is
  modelled by the Mixing length theory and radiation by the radiative
  diffusion approximation. In the second one only radiation is taken
  into account, but radiative diffusion approximation is dropped and
  radiative equilibrium is imposed by an iterative scheme. The presence
  of the magnetic field is mimicked by imposing a lower pressure and
  density in the magnetic region. In order to evaluate the radiation
  field a numerical code, based on the short characteristic technique,
  was developed. A detailed description of the code, as well as results
  obtained by tests aimed to investigate and compare different numerical
  techniques and spurious effects, are presented. The radiative flux
  is finally evaluated by a quadrature scheme. At this aim two schemes
  have been developed and compared. The software developed has allowed to
  investigate radiation field through the flux tube models studied. I show
  that the presence of a magnetic structure generates areas of different
  shapes and contrast around it. These features vary with the position
  of the structures on the solar disk (the sight angle) and have spatial
  scales smaller than the typical scale of a flux tube (about 100 km),
  so resolution better than 0.1 arcsec is required to observe them. The
  contrast of magnetic features varies also in function of the optical
  depth, so that for the same model different center to limb variations
  of the contrast can be observed. This indicates that when observing
  magnetic structures at different wavelengths the contrast can be very
  different, thus partially explaining the discrepant results obtained
  in the literature. Investigation of the results also shows that the
  center to limb variation of the contrast reflects the temperature
  stratification inside and outside the tube. Measurements carried out
  at different wavelengths are thus fundamental for the determination
  of temperature of magnetic structures and for the investigation of
  their physical properties. ii

---------------------------------------------------------
Title: On the reliability of the fractal dimension measure of solar
    magnetic features and on its variation with solar activity
Authors: Criscuoli, S.; Rast, M. P.; Ermolli, I.; Centrone, M.
2007A&A...461..331C    Altcode: 2006astro.ph..9748C
  Context: Several studies have investigated the fractal and multifractal
  nature of magnetic features in the solar photosphere and its variation
  with the solar magnetic activity cycle. <BR />Aims: Here we extend
  those studies by examining the fractal geometry of bright magnetic
  features at higher atmospheric levels, specifically in the solar
  chromosphere. We analyze structures identified in CaIIK images obtained
  with the Precision Solar Photometric Telescopes (PSPTs) at Osservatorio
  Astronomico di Roma (OAR) and Mauna Loa Solar Observatory (MLSO). <BR
  />Methods: Fractal dimension estimates depend on the estimator employed,
  the quality of the images, and the structure identification techniques
  used. We examine both real and simulated data and employ two different
  perimeter-area estimators in order to understand the sensitivity of
  the deduced fractal properties to pixelization and image quality. <BR
  />Results: The fractal dimension of bright “magnetic” features
  in CaIIK images ranges between values of 1.2 and 1.7 for small and
  large structures respectively. This size dependency largely reflects
  the importance of image pixelization in the measurement of small
  objects. The fractal dimension of chromospheric features does not show
  any clear systematic variation with time over the period examined,
  the descending phase of solar cycle 23. <BR />Conclusions: .These
  conclusions, and the analysis of both real and synthetic images on
  which they are based, are important in the interpretation of previously
  reported results.

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Title: SINERGIES (Sun, INterplanetary, EaRth Ground-based InstrumEntS)
    or the potential of the Italian Network for Ground-Based Observations
    of Sun-Earth Phenomena.
Authors: Amata, E.; Candidi, M.; Centrone, M.; Consolini, G.;
   Contarino, L.; Criscuoli, S.; De Lauretis, M.; Diego, P.; Ermolli,
   I.; Francia, P.; Giorgi, F.; Laurenza, M.; Magrí, M.; Marcucci, F.;
   Massetti, S.; Messerotti, M.; Oliviero, M.; Penza, V.; Perna, C.;
   Pietropaolo, E.; Romano, P.; Severino, G.; Spadaro, D.; Storini, M.;
   Vellante, M.; Villante, U.; Zlobec, P.; Zuccarello, F.
2006MSAIS...9...82A    Altcode:
  The Italian Network for Ground-Based Observations of Sun-Earth
  Phenomena, whose instruments monitor the Sun, the Interplanetary
  Space, and the Earth's Magnetosphere, has recently started to operate
  in a coordinated scheme. In this paper, we describe few significant
  examples of this coordination effort. 1) During the year 2003, several
  coordinated observational campaigns were carried out in order to study
  the solar photospheric dynamics. 2) Reconstruction of TSI in time, for
  periods spanning from a solar rotation up to the whole current solar
  cycle. 3) Extreme solar events occurring during the late October -
  early November 2003.

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Title: SINERGIES, the Italian Network for Ground-Based Observations
    of Sun-Earth Phenomena .
Authors: Amata, E.; Berrilli, F.; Candidi, M.; Cantarano, S.; Centrone,
   M.; Consolini, G.; Contarino, L.; Criscuoli, S.; De Lauretis, M.;
   Del Moro, D.; Egidi, A.; Ermolli, I.; Francia, P.; Giordano, S.;
   Giorgi, F.; Oliviero, M.; Magrí, M.; Marcucci, F.; Massetti, S.;
   Messerotti, M.; Parisi, M.; Perna, C.; Pietropaolo, E.; Romano, P.;
   Severino, G.; Spadaro, D.; Storini, M.; Vellante, M.; Villante, U.;
   Zlobec, P.; Zuccarello, F.
2006MSAIS...9...79A    Altcode:
  Since many years, the complex phenomena occurring on the Sun have
  been continuously monitored by different and complementary ground
  based instruments managed by groups of the Italian Astrophysics
  Community. Recently some of these instruments have started to operate in
  a coordinated scheme, the Italian Network for Ground-Based Observations
  of Sun-Earth Phenomena. In this paper, we describe the characteristics
  of the nodes belonging to the Network, called SINERGIES, the scientific
  objectives, the facilities and the data storage system of the Network
  itself. Due to its capabilities, the Network allows the Italian Solar
  Terrestrial Physics Community to monitor solar activity and its effect
  on the Earth.

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Title: First Implementation Of Phase Diversity At Themis
Authors: Criscuoli, S.; Moro, D. Del; Bonet, J. A.; Márquez, I.
2005SoPh..228..177C    Altcode:
  Phase diversity techniques are robust post-processing tools for image
  enhancement and correction of telescopic and atmospheric induced
  aberrations. We present results obtained applying the Partitioned
  Phase-Diverse Speckle (PPDS) technique to images acquired at THEMIS. We
  also present an image quality estimator based on image power spectrum
  content we developed in order to automatically evaluate the results
  of large amount of data.

---------------------------------------------------------
Title: A study of the photometrical properties of solar magnetic
    features by numerical simulation
Authors: Criscuoli, S.; Rast, M. P.
2005MmSAI..76..945C    Altcode:
  Existing numerical simulations reproduce many of the observed
  geometrical and photometrical characteristics of solar magnetic
  structures. Nonetheless, some quite fundemental properties, such as
  network center-to-limb variation and facular contrast, which depend on
  both the structure's size and magnetic field intensity, are still only
  partially understood. In order to investigate these problems, we have
  developed a radiative transfer code, based on the short characteristics
  method, that enables detailed study of the radiative properties of
  individual magnetic flux tubes and unresolved aggregates of them.

---------------------------------------------------------
Title: Phase diversity at THEMIS : first implementation
Authors: Del Moro, D.; Criscuoli, S.; Bonet, J. A.; Márquez, I.;
   Lemen, C.; Briand, C.
2003MmSAI..74..811D    Altcode:
  Phase diversity techniques actually provide robust post-processing
  methods to restore solar images degraded by seeing-optical
  aberrations. We present preliminary results of the application of a
  Partitioned Phase-Diverse Speckle (PPDS) technique at THEMIS. The images
  have been acquired using the IPM broad-band CCD camera and reduced
  using a suitable IDL code. The spectral analysis of unrestored/restored
  images shows a significant improvement of image quality, achieving
  diffraction limited resolution.

---------------------------------------------------------
Title: Phase diversity at THEMIS : first implementation
Authors: Del Moro, D.; Lemen, C.; Bonet, J. A.; Márquez, I.;
   Criscuoli, S.; Briand, C.
2003AN....324..299D    Altcode:
  No abstract at ADS

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Title: Restoring full-disk images for atmospheric and instrumental
    degradation effects
Authors: Criscuoli, S.; Ermolli, I.
2003MmSAI..74..607C    Altcode:
  A numerical technique developed to recover atmospheric and instrumental
  degradation effects on full-disk images of the solar atmosphere
  acquired with a medium resolution will be presented. This technique,
  based on the method proposed by Walton and Preminger (1999), allows
  simultaneous determination of the undisturbed solar limb darkening
  profile and the characterization of the Point Spread Function in
  terms of a small number of analytic parameters. The application
  of the technique allows to remove stray light effects from images,
  to a great extent, while preserves the data photometry. The results
  obtained applying this technique to a sample of full-disk images taken
  with the PSPT telescopes will be summarized.

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Title: CONCORDIASTRO/Italy: A Solar High-Resolution Observation
    Program at Dome-C
Authors: Severino, G.; Andretta, V.; Berrilli, F.; Cascone, E.;
   Centrone, M.; Criscuoli, S.; Del Moro, D.; Ermolli, I.; Giorgi, F.;
   Jefferies, S. M.; Magri, M.; Moretti, P. F.; Oliviero, M.; Parisi,
   L.; V; Porzio; Smaldone, L. A.; Straus, Th.
2003MSAIS...2..181S    Altcode:
  CONCORDIASTRO is the Nice-Napoli joint project for site
  testing of the Dome C for solar and stellar astronomy in the
  visible. CONCORDIASTRO/Italy is the solar physics part of this project,
  whose the Napoli team has the principal responsibility. Beyond the
  well-known interest for the helioseismology, CONCORDIASTRO/Italy pointed
  out that, because of its special atmospheric conditions, Dome C promises
  to be one of the best sites on Earth to perform high-resolution solar
  physics. Here we review the basis for this statement and the solar
  observations program planned by CONCORDIASTRO/Italy.

---------------------------------------------------------
Title: From the minimum to the maximum: the quality of Rome-PSPT
    images
Authors: Fazzari, C.; Ermolli, I.; Centrone, M.; Criscuoli, S.;
   Giorgi, F.
2003MmSAI..74..667F    Altcode:
  In response to the need for both measurement and interpretation of
  irradiance variations, two PSPTs (Precision Solar Photometric Telescope)
  have been designed and produced in the framework of the RISE (Radiative
  Inputs of the Sun to Earth) project, to provide high-precision (0.1%)
  photometric observations of the solar disk, with about 1 arcsec
  spatial resolution at three wavelength bands. As well known, these
  two PSPTs, installed at the Rome and the Mauna Loa Observatories,
  since 1996 provide daily observation of the Sun available to the
  community at the internet addresses http://www.mporzio.astro.it and
  http://www.rise.hao.ucar.edu. We present the results obtained analyzing
  the quality of the images acquired by the two PSPTs, with particular
  regard to photometric accuracy, spatial scale, scattered light level
  and temporal variations of the image quality.

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Title: Analysis of high resolution and full disk solar images
Authors: Berrilli, F.; Caccin, B.; Cantarano, S.; Egidi, A.; Penza,
   V.; Criscuoli, S.; del Moro, D.; Pietropaolo, E.; Consolini, G.;
   Ermolli, I.; Lepreti, F.; Mainella, G.; Severino, G.; Zuccarello, F.
2001ESASP.493..173B    Altcode: 2001sefs.work..173B
  No abstract at ADS