Author name code: mcateer ADS astronomy entries on 2022-09-14 author:"McAteer, R.T. James" ------------------------------------------------------------------------ Title: Call and Response: A Time-resolved Study of Chromospheric Evaporation in a Large Solar Flare Authors: Sellers, Sean G.; Milligan, Ryan O.; McAteer, R. T. James Bibcode: 2022ApJ...936...85S Altcode: 2022arXiv220814347S We studied an X1.6 solar flare produced by NOAA Active Region 12602 on 2014 October 22. The entirety of this event was covered by RHESSI, IRIS, and Hinode/EIS, allowing analysis of the chromospheric response to a nonthermal electron driver. We derived the energy contained in nonthermal electrons via RHESSI spectral fitting and linked the time-dependent parameters of this call to the response in Doppler velocity, density, and nonthermal width across a broad temperature range. The total energy injected was 4.8 × 1030 erg and lasted 352 s. This energy drove explosive chromospheric evaporation, with a delineation in both Doppler and nonthermal velocities at the flow reversal temperature, between 1.35 and 1.82 MK. The time of peak electron injection (14:06 UT) corresponded to the time of highest velocities. At this time, we found 200 km s-1 blueshifts in the core of Fe XXIV, which is typically assumed to be at rest. Shortly before this time, the nonthermal electron population had the shallowest spectral index (≍6), corresponding to the peak nonthermal velocity in Si IV and Fe XXI. Nonthermal velocities in Fe XIV, formed near the flow reversal temperature, were low and not correlated with density or Doppler velocity. Nonthermal velocities in ions with similar temperatures were observed to increase and correlate with Doppler velocities, implying unresolved flows surrounding the flow reversal point. This study provides a comprehensive, time-resolved set of chromospheric diagnostics for a large X-class flare, along with a time-resolved energy injection profile, ideal for further modeling studies. Title: Detection of Venusian Aurora During Parker Solar Probe Encounter Authors: Kovac, Sarah; Gray, Candace; Arge, Charles; Mcateer, R. T. James; Chanover, Nancy; Churchill, Chris; Szabo, Adam Bibcode: 2021AGUFM.P45F2487K Altcode: We cannot fully understand key topics in planetary science, like formation and evolution of planetary atmospheres, without accounting for their interactions with the solar wind. The presence of aurora is an important manifestation and tracer of the interaction between the solar wind and planetary ionospheres. The OI (1S-1D) 557.7 nm (oxygen green line) is a bright auroral line in the terrestrial atmosphere and is detected on the Venusian nightside after major solar storms. Currently, the processes responsible for producing the green line emission on Venus are poorly understood, yet the observed variability of this feature is clearly linked to the solar wind environment. Here, we use the Wang-Sheeley-Arge (WSA) model and in situ data from Parker Solar Probe (PSP) to look at the solar wind conditions during detections of the Venusian green line when PSP was at its closest encounters with Venus. 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 Bibcode: 2021SoPh..296...70R Altcode: 2020arXiv200808203R The National Science Foundation's Daniel K. Inouye Solar Telescope (DKIST) will revolutionize our ability to measure, understand, and model the basic physical processes that control the structure and dynamics of the Sun and its atmosphere. The first-light DKIST images, released publicly on 29 January 2020, only hint at the extraordinary capabilities that will accompany full commissioning of the five facility instruments. With this Critical Science Plan (CSP) we attempt to anticipate some of what those capabilities will enable, providing a snapshot of some of the scientific pursuits that the DKIST hopes to engage as start-of-operations nears. The work builds on the combined contributions of the DKIST Science Working Group (SWG) and CSP Community members, who generously shared their experiences, plans, knowledge, and dreams. Discussion is primarily focused on those issues to which DKIST will uniquely contribute. Title: Spatial and Temporal Analysis of 3 minute Oscillations in the Chromosphere Associated with the X2.2 Solar Flare on 2011 February 15 Authors: Farris, Laurel; McAteer, R. T. James Bibcode: 2020ApJ...903...19F Altcode: 2020arXiv201110074F Three minute oscillations in the chromosphere are attributed to both slow magnetoacoustic waves propagating from the photosphere and to oscillations generated within the chromosphere itself at its natural frequency as a response to a disturbance. Here we present an investigation of the spatial and temporal behavior of the chromospheric 3 minute oscillations before, during, and after the SOL2011-02-15T01:56 X2.2 flare. Observations in ultraviolet emission centered on 1600 and 1700 Å obtained at 24 s cadence from the Atmospheric Imaging Assembly on board the Solar Dynamics Observatory are used to create power maps as functions of both space and time. We observe higher 3 minute power during the flare, spatially concentrated in small areas ∼10 pixels ( $\sim 4^{\prime\prime} $ ) across. This implies that the chromospheric plasma is not oscillating globally as a single body. The locations of increased 3 minute power are consistent with observations of HXR flare emission from previous studies, suggesting that these small areas are manifestations of the chromosphere responding to injection of energy by nonthermal particles. This supports the theory that the chromosphere oscillates at the acoustic cutoff frequency in response to a disturbance. Title: The Slowly Varying Corona. II. The Components of F 10.7 and Their Use in EUV Proxies Authors: Schonfeld, S. J.; White, S. M.; Henney, C. J.; Hock-Mysliwiec, R. A.; McAteer, R. T. J. Bibcode: 2019ApJ...884..141S Altcode: 2019arXiv191012964S Using four years of full-disk-integrated coronal differential emission measures calculated in Schonfeld et al. (2017), we investigate the relative contribution of bremsstrahlung and gyroresonance emission in observations of F 10.7, the 10.7 cm (2.8 GHz) solar microwave spectral flux density and commonly used activity proxy. We determine that the majority of coronal F 10.7 is produced by the bremsstrahlung mechanism, but the variability observed over individual solar rotations is often driven by gyroresonance sources rotating across the disk. Our analysis suggests that the chromosphere may contribute significantly to F 10.7 variability and that coronal bremsstrahlung emission accounts for 14.2 ± 2.1 sfu (∼20%) of the observed solar minimum level. The bremsstrahlung emission has a power-law relationship to the total F 10.7 at high activity levels, and this combined with the observed linearity during low activity yields a continuously differentiable piecewise fit for the bremsstrahlung component as a function of F 10.7. We find that the bremsstrahlung component fit, along with the Mg II index, correlates better with the observed 5-37 nm spectrum than the common 81 day averaged F 10.7 proxy. The bremsstrahlung component of F 10.7 is also well approximated by the moderate-strength photospheric magnetic field parameterization from Henney et al. (2012), suggesting that it could be forecast for use in both atmospheric research and operational models. Title: A Potential Field is Unique…Right?!? Summary of Evaluation Methodology and Initial Results Authors: Leka, K. D.; Barnes, Graham; McAteer, R. T. James Bibcode: 2019shin.confE.151L Altcode: Given the normal component of the magnetic field on a closed surface, the lowest-energy construct is the potential field, and mathematically it is a unique construct. In solar physics, so much of what we are interested in - free energy, magnetic shear, magnetic topology, helicity - is estimated relative to the potential field. However, when methods and results for quantities of interest (e.g. the Campaign on Energy Storage session at SHINE 2015) what quickly becomes apparent is that the methods of computing potential fields themselves can lead to wildly different results - so that comparisons of, for example, NLFFF-derived free energy are all but meaningless between publications.

In this session we explore computing this all-important starting point, asking, (1) What is the magnitude of differences between different potential-field calculations? (2) What implementations can mitigate some of the worst discrepancies? with the goal of establishing community-supported potential-field methodologies to bring better quantitative prospects to our science.

We focus separately on global and local calculations with attention to boundary treatment, resolution, and implementation details. Participants have prepared potential-field calculations for 2012.06.13_11:36_TAI and/or NOAA AR 11504 for comparisons, as detailed in the session description. With this session scheduled for Friday, we summarize in a poster the submitted solutions (as of the start of the week, more welcome through Wednesday!), evaluation methodologies, and results. In this way, SHINE 2019 participants can be aware of these results earlier in the week, for context to discussions in earlier relevant sessions.

This work was partially funded by NASA HSR grant 80NSSC18K0071 and supported by the US National Science Foundation under Grant No. 1630454. Any opinions, findings, and conclusions or recommendations expressed in this material are those of the authors and do not necessarily reflect the views of the National Science Foundation. Title: Oscillatory power in the chromosphere: a multi-flare study Authors: Farris, Laurel Elizabeth; McAteer, R. T. James Bibcode: 2019shin.confE.208F Altcode: Preliminary results of the spatial distribution of acoustic oscillatory power in the chromosphere associated with multiple flares are presented, obtained using observations from SDO/AIA. We employ FFT and wavelet analysis techniques to determine the location, time, and duration of both enhancement and suppression of acoustic power in small subregions of the active region before, during, and after the flare. Changes in oscillatory behavior prior to flare onset may have significant implications in the field of space weather prediction, while enhanced oscillations that persist through the gradual phase and beyond will provide further insight to the theory that the chromosphere naturally oscillates at a frequency equal to the acoustic cutoff at approximately 5.6 mHz (3 minutes). Moreover, the investigation of multiple flares will provide statistically significant results and will contribute to the global understanding of the flaring chromosphere. Title: Synoptic Studies of the Sun as a Key to Understanding Stellar Astrospheres Authors: Martinez Pillet, Valentin; Hill, Frank; Hammel, Heidi B.; de Wijn, Alfred G.; Gosain, Sanjay; Burkepile, Joan; Henney, Carl; McAteer, R. T. James; Bain, Hazel; Manchester, Ward; Lin, Haosheng; Roth, Markus; Ichimoto, Kiyoshi; Suematsu, Yoshinori Bibcode: 2019BAAS...51c.110M Altcode: 2019astro2020T.110M; 2019arXiv190306944M Ground-based solar observations provide key contextual data (i.e., the "big picture") to produce a complete description of the only astrosphere we can study in situ: our Sun's heliosphere. This white paper outlines the current paradigm for ground-based solar synoptic observations, and indicates those areas that will benefit from focused attention. Title: Spatial and temporal localization of enhanced chromospheric 3-minute oscillations before, during, and after the 2011-February-15 X2.2 flare Authors: Farris, Laurel Elizabeth; McAteer, Robert T. J. Bibcode: 2018shin.confE.257F Altcode: The ubiquitous 3-minute oscillations of the chromosphere are attributed to both slow magnetoacoustic waves with frequencies higher than the acoustic cutoff propagating from the photosphere, and to oscillations generated as a response to a disturbance within the chromosphere itself at its natural frequency. Here we present an analysis of ultraviolet images obtained at 24-second cadence from the Atmospheric Imaging Assembly (AIA) on board the Solar Dynamics Observatory (SDO) to investigate the spatial and temporal behavior of the chromospheric 3-minute oscillations before, during, and after the SOL2011-02-15T01:56 X2.2 flare. A Fourier transform is applied to the intensity signal over time segments of 25.6 minutes, and shifted through a five-hour time series centered on the flare. This was done for individual pixels to generate power maps that allow the examination of the 3-minute power in both space and time. We find that enhancement in the 3-minute power is concentrated in small areas over sunspot umbral regions. Temporal variations of the 3-minute power from a non-detrended signal show an enhancement during the flare with several distinct peaks, though improved temporal resolution is likely needed for conclusive results. The potential correlation between 3-minute power and magnetic field strength is discussed, along with formation height dependencies. Title: EUV Irradiance from the EVE MEGS-A Dataset and its Implications for F10.7 Authors: Schonfeld, Samuel; White, Stephen M.; Hock-Mysliwiec, Rachel; Henney, Carl J.; Mcateer, R. T. James Bibcode: 2018tess.conf40906S Altcode: We present analysis of the complete spectral dataset from the Extreme-ultraviolet (EUV) Variability Experiment (EVE) MEGS-A instrument. Using these data, we construct daily differential emission measures (DEMs) and use them to analyze the long-term variability of the global corona and the irradiance it produces. We identify a discontinuity in the EUV irradiance and DEMs separating solar minimum and maximum conditions. Using the DEMs we also study the relationship between EUV and F10.7, the 10.7 cm (2.8 GHz) solar activity proxy. We compare predictions of the geoeffective F10.7 from the DEMs and photospheric magnetic field observations with the commonly used 81-day averaged F10.7 to investigate their uses in parameterizing the solar EUV irradiance. We demonstrate a fundamental variability in the relationship between F10.7 and EUV associated with the two coronal sources of F10.7 emission. Title: Pipeline development for routine chromospheric magnetic field inversions of DST/FIRS observations Authors: Wang, Shuo; Schad, Thomas A.; Mcateer, R. T. James Bibcode: 2018tess.conf30819W Altcode: The Facility Infrared Spectropolarimeter (FIRS) at the Dunn Solar Telescope (DST) provides efficient mapping of the full Stokes vector in the chromospheric He I triplet at 1083 nm across solar targets. The inversion of this type of data to achieve measurements of the magnetic field vector plays a key role in understanding chromospheric active region topologies and is especially useful in studying solar filaments and prominences. As a baseline supporting future synoptic magnetic observations of solar filaments at the DST, we demonstrate first steps in implementing a new pipeline that inverts FIRS data using the "Hanle and Zeeman Light" (HAZEL) code, which incorporates all the relevant atomic-level and Zeeman effect mechanisms. Inverted wide-field observations (170'' x 70'') of NOAA AR 12470 on December 14, 2015, exhibit our ability to recover reliable field measurements using multiple parallel FIRS slits. Using this pipeline, further analysis of active region magnetic fields may shed light on the formation and eruption processes of active region filaments. Title: Prediction of Solar Flares from Magnetograms using Transfer Learning on Convolutional Neural Networks Authors: Vincent, Ty; Boucheron, Laura; Mcateer, R. T. James Bibcode: 2018tess.conf32203V Altcode: Solar flares are the result of the rapid conversion of stored magnetic energy to particle acceleration and radiation in the corona. Most current automated methods for predicting solar flares from magnetograms use a process of feature extraction followed by classification. In feature extraction some number of features are extracted from the magnetogram image in order to quantify and characterize the state and complexity of the photospheric magnetic field. The classification algorithm then learns to separate flaring from non-flaring regions within the feature space by defining a decision boundary that separates the two classes. In contrast recent advances in deep learning, namely convolutional neural networks (CNNs), have introduced methods that can simultaneously learn both the features and the decision boundary. A CNN-based flare prediction thus does not require a pre-defined feature space but instead learns the features that best separate flaring from non-flaring regions. CNNs are computationally complex to train and require large amounts of training data. However, recent work has shown that networks trained for other applications can be adapted to new problems with limited training data and computational overhead. In this process of transfer learning, a CNN trained on a large image dataset is used and only the final layers are retrained on a new data set. In this work, we study the the performance of solar flare prediction using transfer learning on CNNs and report on the high level features defined by the CNN that may potentially identify underlying phenomenon that lead active regions to flare. Title: The Slowly Varying Corona. I. Daily Differential Emission Measure Distributions Derived from EVE Spectra Authors: Schonfeld, S. J.; White, S. M.; Hock-Mysliwiec, R. A.; McAteer, R. T. J. Bibcode: 2017ApJ...844..163S Altcode: 2017arXiv170609525S Daily differential emission measure (DEM) distributions of the solar corona are derived from spectra obtained by the Extreme-ultraviolet Variability Experiment (EVE) over a 4 yr period starting in 2010 near solar minimum and continuing through the maximum of solar cycle 24. The DEMs are calculated using six strong emission features dominated by Fe lines of charge states viii, ix, xi, xii, xiv, and xvi that sample the nonflaring coronal temperature range 0.3-5 MK. A proxy for the non-Fe xviii emission in the wavelength band around the 93.9 Å line is demonstrated. There is little variability in the cool component of the corona (T < 1.3 MK) over the 4 yr, suggesting that the quiet-Sun corona does not respond strongly to the solar cycle, whereas the hotter component (T > 2.0 MK) varies by more than an order of magnitude. A discontinuity in the behavior of coronal diagnostics in 2011 February-March, around the time of the first X-class flare of cycle 24, suggests fundamentally different behavior in the corona under solar minimum and maximum conditions. This global state transition occurs over a period of several months. The DEMs are used to estimate the thermal energy of the visible solar corona (of order 1031 erg), its radiative energy loss rate ((2.5-8) × {10}27 erg s-1), and the corresponding energy turnover timescale (about an hour). The uncertainties associated with the DEMs and these derived values are mostly due to the coronal Fe abundance and density and the CHIANTI atomic line database. Title: Quasi-periodic oscillations in flare emission in the solar chromosphere simultaneously observed with IRIS and SDO Authors: Farris, Laurel Elizabeth; McAteer, R. T. James Bibcode: 2017shin.confE.164F Altcode: Quasi-periodic pulsations (QPPs) appear in the emission spectrum of most solar flares over all wavelength bands and, in some cases, multiple periodicities. There is some ambiguity as to the type of emission in which they occur (i.e. line or continuum), and the mechanism that drives them. Current possibilities include magnetohydrodynamic oscillations and plasma flows of non-thermal electrons after the magnetic reconnection process. Here, we investigate the response of the chromosphere to solar flares by inspecting the power of the 3-minute oscillations before, during and after flares, in order to constrain both the start time of this power and where it originates. For this preliminary study, we present analysis of continuum images from the Helioseismic and Magnetic Imager (HMI) and of 1600 and 1700 Angstrom UV images from the Atmospheric Imaging Assembly (AIA), two of the instruments on board the Solar Dynamics Observatory (SDO), of the 2011 February 15 X-class flare. Future work will involve the Interface Region Imaging Spectrometer (IRIS) to show whether the oscillations are manifest in the line or continuum emission, a distinction that can be lost in integrated bandpass intensity images. Results from wavelet analysis and Fourier transforms will be explored. Title: On the Non-Kolmogorov Nature of Flare-productive Solar Active Regions Authors: Mandage, Revati S.; McAteer, R. T. James Bibcode: 2016ApJ...833..237M Altcode: 2016arXiv161100830M A magnetic power spectral analysis is performed on 53 solar active regions, observed from 2011 August to 2012 July. Magnetic field data obtained from the Helioseismic and Magnetic Imager, inverted as Active Region Patches, are used to study the evolution of the magnetic power index as each region rotates across the solar disk. Active regions are classified based on the numbers and sizes of solar flares they produce in order to study the relationship between flare productivity and the magnetic power index. The choice of window size and inertial range plays a key role in determining the correct magnetic power index. The overall distribution of magnetic power indices has a range of 1.0-2.5. Flare-quiet regions peak at a value of 1.6. However, flare-productive regions peak at a value of 2.2. Overall, the histogram of the distribution of power indices of flare-productive active regions is well separated from flare-quiet active regions. Only 12% of flare-quiet regions exhibit an index greater than 2, whereas 90% of flare-productive regions exhibit an index greater than 2. Flare-quiet regions exhibit a high temporal variance (I.e., the index fluctuates between high and low values), whereas flare-productive regions maintain an index greater than 2 for several days. This shows the importance of including the temporal evolution of active regions in flare prediction studies, and highlights the potential of a 2-3 day prediction window for space weather applications. Title: Correcting F10.7 for use in Ionospheric Models Authors: Schonfeld, S.; White, S.; Hock, R. A.; Henney, C. J.; Mcateer, R. T. J.; Arge, C. N. Bibcode: 2016AGUFMSA53B2449S Altcode: The F10.7 (10.7 cm, 2.8 GHZ) radio flux has been used as a proxy for solar extreme ultraviolet (EUV) emission in ionospheric models for decades. An often ignored complication when using F10.7 as an EUV proxy is the fact that there are two different mechanisms in the solar corona responsible for creating F10.7, bremsstrahlung that correlates well with EUV, and gyroresonance that does not. We present an overview of the issues caused by the F10.7 source ambiguity and new results identifying the contribution from each generation mechanism over a four year period during the rising phase of solar cycle 24. This allows for an empirical correction that we compare with the F10.7 inputs traditionally used in ionospheric modelling and we discuss the implications of these results for past and future models. Title: A Comparison of Flare Forecasting Methods. I. Results from the “All-Clear” Workshop Authors: Barnes, G.; Leka, K. D.; Schrijver, C. J.; Colak, T.; Qahwaji, R.; Ashamari, O. W.; Yuan, Y.; Zhang, J.; McAteer, R. T. J.; Bloomfield, D. S.; Higgins, P. A.; Gallagher, P. T.; Falconer, D. A.; Georgoulis, M. K.; Wheatland, M. S.; Balch, C.; Dunn, T.; Wagner, E. L. Bibcode: 2016ApJ...829...89B Altcode: 2016arXiv160806319B Solar flares produce radiation that can have an almost immediate effect on the near-Earth environment, making it crucial to forecast flares in order to mitigate their negative effects. The number of published approaches to flare forecasting using photospheric magnetic field observations has proliferated, with varying claims about how well each works. Because of the different analysis techniques and data sets used, it is essentially impossible to compare the results from the literature. This problem is exacerbated by the low event rates of large solar flares. The challenges of forecasting rare events have long been recognized in the meteorology community, but have yet to be fully acknowledged by the space weather community. During the interagency workshop on “all clear” forecasts held in Boulder, CO in 2009, the performance of a number of existing algorithms was compared on common data sets, specifically line-of-sight magnetic field and continuum intensity images from the Michelson Doppler Imager, with consistent definitions of what constitutes an event. We demonstrate the importance of making such systematic comparisons, and of using standard verification statistics to determine what constitutes a good prediction scheme. When a comparison was made in this fashion, no one method clearly outperformed all others, which may in part be due to the strong correlations among the parameters used by different methods to characterize an active region. For M-class flares and above, the set of methods tends toward a weakly positive skill score (as measured with several distinct metrics), with no participating method proving substantially better than climatological forecasts. Title: Segmentation of Coronal Holes Using Active Contours Without Edges Authors: Boucheron, L. E.; Valluri, M.; McAteer, R. T. J. Bibcode: 2016SoPh..291.2353B Altcode: 2016SoPh..tmp..154B; 2016arXiv161001023B An application of active contours without edges is presented as an efficient and effective means of extracting and characterizing coronal holes. Coronal holes are regions of low-density plasma on the Sun with open magnetic field lines. The detection and characterization of these regions is important for testing theories of their formation and evolution, and also from a space weather perspective because they are the source of the fast solar wind. Coronal holes are detected in full-disk extreme ultraviolet (EUV) images of the corona obtained with the Solar Dynamics Observatory Atmospheric Imaging Assembly (SDO/AIA). The proposed method detects coronal boundaries without determining any fixed intensity value in the data. Instead, the active contour segmentation employs an energy-minimization in which coronal holes are assumed to have more homogeneous intensities than the surrounding active regions and quiet Sun. The segmented coronal holes tend to correspond to unipolar magnetic regions, are consistent with concurrent solar wind observations, and qualitatively match the coronal holes segmented by other methods. The means to identify a coronal hole without specifying a final intensity threshold may allow this algorithm to be more robust across multiple datasets, regardless of data type, resolution, and quality. Title: Inferring Magnetic Fields and Electron Densities from Coronal Seismology Authors: McAteer, R. T. J.; Ireland, J. Bibcode: 2016usc..confE..54M Altcode: The solar corona oscillates at many different spatial sizes and temporal size scales. However, much remains unknown about many of these oscillations: they are intermittent for unknown reasons; appear on some coronal features and not on others; and may, or may not, be magnetohydrodynamic (MHD) wave modes. Using a series of automated oscillation detection routines, we extract space-time-density maps from a quagmire of oscillating loops. From these data products, we extract coronal magnetic fields and densities in order to to differentiate between potential excitation mechanisms and between potential damping mechanisms. The spread of periods, amplitudes, and damping times, allow us to map the spatial distribution of these parameters. Initial periods of P 300-500s, result in inferred coronal magnetic field of B 20G-50G. The decrease in the oscillation period of the loop position corresponds to a drop in number density inside each coronal loop, as predicted by MHD. As the the period drops below a threshold of P 300s, our MHD model cannot explain the sudden observed decrease in both period and density and so a secondary dissipation mechanism must occur at this point in time and space. Title: An overview of coronal seismology and application to data from AIA/SDO Authors: Farris, Laurel; McAteer, R. T. James Bibcode: 2016shin.confE.201F Altcode: Coronal seismology involves the investigation of magnetohydrodynamic (MHD) waves and oscillatory phenomena that arise in the solar corona. Properties of the observed modes are largely dependent on their environment, and therefore can be used to extract atmospheric parameters that are otherwise difficult to observe. The general theory behind MHD phenomena is investigated here, along with the characteristics of different modes and the information that can be extracted from them. A few methods are applied to data from the Atmospheric Imaging Assembly (AIA) instrument on the Solar Dynamics Observatory (SDO). Title: F10.7 and the slowly varying corona from EVE DEMs Authors: Schonfeld, Sam; White, S. M.; Hock, R. A.; McAteer, R. T. J. Bibcode: 2016shin.confE.193S Altcode: We present a differential emission measure (DEM) analysis of the slowly varying corona during the first half of solar cycle 24. Using the Extreme ultraviolet Variability Experiment (EVE) and the CHIANTI atomic line database we identify strong isolated iron emission lines present in the non-flaring spectrum with peak emissions covering the coronal temperature range of 5.7 < log(T) < 6.5. These lines are used to generate daily DEMs from EVE spectra to observe the long term variability of global coronal thermal properties. We discuss the choice of emission lines and the implications of this data set for the relationship between EUV and the F10.7 radio flux. Title: Observation of the Evolution of a Current Sheet in a Solar Flare Authors: Zhu, Chunming; Liu, Rui; Alexander, David; McAteer, R. T. James Bibcode: 2016ApJ...821L..29Z Altcode: 2016arXiv160307062Z We report multi-wavelength and multi-viewpoint observations of a solar eruptive event that involves loop-loop interactions. During a C2.0 flare, motions associated with inflowing and outflowing plasma provide evidence for ongoing magnetic reconnection. The flare loop top and a rising “concave-up” feature are connected by a current-sheet-like structure (CSLS). The physical properties (thickness, length, temperature, and density) of the CSLS are evaluated. In regions adjacent to the CSLS, the EUV emission (characteristic temperature at 1.6 MK) begins to increase more than 10 minutes prior to the onset of the flare, and steeply decreases during the decay phase. The reduction of the emission resembles that expected from coronal dimming. The dynamics of this event imply a magnetic reconnection rate in the range 0.01-0.05. Title: Solar flares, Ampere's Law, and the Search for Units in Scale-Free Processes Authors: McAteer, R. T. James Bibcode: 2016IAUFM..29B.732M Altcode: One of the most powerful SOC tools - the wavelet transform modulus maxima approach to calculating multifractality - is connected to one of the most powerful equations in all of physics - Ampere's law. In doing so, the multifractal spectra can be expressed in terms of current density, and how current density can then be used for the prediction of future energy release from such a system. Title: 25 Years of Self-organized Criticality: Numerical Detection Methods Authors: McAteer, R. T. James; Aschwanden, Markus J.; Dimitropoulou, Michaila; Georgoulis, Manolis K.; Pruessner, Gunnar; Morales, Laura; Ireland, Jack; Abramenko, Valentyna Bibcode: 2016SSRv..198..217M Altcode: 2015SSRv..tmp...31M; 2015arXiv150608142M The detection and characterization of self-organized criticality (SOC), in both real and simulated data, has undergone many significant revisions over the past 25 years. The explosive advances in the many numerical methods available for detecting, discriminating, and ultimately testing, SOC have played a critical role in developing our understanding of how systems experience and exhibit SOC. In this article, methods of detecting SOC are reviewed; from correlations to complexity to critical quantities. A description of the basic autocorrelation method leads into a detailed analysis of application-oriented methods developed in the last 25 years. In the second half of this manuscript space-based, time-based and spatial-temporal methods are reviewed and the prevalence of power laws in nature is described, with an emphasis on event detection and characterization. The search for numerical methods to clearly and unambiguously detect SOC in data often leads us outside the comfort zone of our own disciplines—the answers to these questions are often obtained by studying the advances made in other fields of study. In addition, numerical detection methods often provide the optimum link between simulations and experiments in scientific research. We seek to explore this boundary where the rubber meets the road, to review this expanding field of research of numerical detection of SOC systems over the past 25 years, and to iterate forwards so as to provide some foresight and guidance into developing breakthroughs in this subject over the next quarter of a century. Title: Spatial variation of AIA coronal Fourier power spectra Authors: Ireland, J.; Mcateer, R. T. J. Bibcode: 2015AGUFMSH54B..01I Altcode: We describe a study of the spatial distribution of the properties of the Fourier power spectrum of time-series of AIA 171Å and 193Å data. The area studied includes examples of physically different components of the corona, such as coronal moss, a sunspot, quiet Sun and fan loop footpoints. We show that a large fraction of the power spectra are well modeled by a power spectrum that behaves like a power law f-n (n>0)at lower frequencies f, dropping to a constant value at higher frequencies. We also show that there are areas where the power spectra are better described by the above power spectrum model, plus a narrow band oscillatory feature, centered in the 3-5 minute oscillation range. These narrow-band spectral features are thought to be due to the propagation of oscillations from lower down in solar atmosphere to hotter. This allows us to produce maps of large areas of the corona showing where the propagation from one waveband to another does and does not occur. This is an important step in understanding wave propagation in different layers in the corona. We also show the 171Å and 193Å power spectrum power law indices are correlated, with 171Å power law indices in the range n = 1.8 to 2.8, and 193Å power law indices n = 2 to 3.5 approximately. Maps of the power law index show that different ranges of values of the power law indices occur in spatially contiguous parts of the corona, indicating that local spatial structure may play a role in defining the power law index value. Taken with our previous result from Ireland et al. (2015) that physically different parts of the corona have different mean values of the power law index, this new result strongly suggests that the same mechanism producing the observed power law power spectrum is operating everywhere across the corona. We discuss the nanoflare hypothesis as a possible explanation of these observations. Title: Complex Flare Dynamics Initiated by a Filament-Filament Interaction Authors: Zhu, Chunming; Liu, Rui; Alexander, David; Sun, Xudong; McAteer, R. T. James Bibcode: 2015ApJ...813...60Z Altcode: 2015arXiv150705889Z We report on an eruption involving a relatively rare filament-filament interaction on 2013 June 21, observed by SDO and STEREO-B. The two filaments were separated in height with a “double-decker” configuration. The eruption of the lower filament began simultaneously with a descent of the upper filament, resulting in a convergence and direct interaction of the two filaments. The interaction was accompanied by the heating of surrounding plasma and an apparent crossing of a loop-like structure through the upper filament. The subsequent coalescence of the filaments drove a bright front ahead of the erupting structures. The whole process was associated with a C3.0 flare followed immediately by an M2.9 flare. Shrinking loops and descending dark voids were observed during the M2.9 flare at different locations above a C-shaped flare arcade as part of the energy release, giving us unique insight into the flare dynamics. Title: Prediction of Solar Flare Size and Time-to-Flare Using Support Vector Machine Regression Authors: Boucheron, Laura E.; Al-Ghraibah, Amani; McAteer, R. T. James Bibcode: 2015ApJ...812...51B Altcode: 2015arXiv151101941B We study the prediction of solar flare size and time-to-flare using 38 features describing magnetic complexity of the photospheric magnetic field. This work uses support vector regression to formulate a mapping from the 38-dimensional feature space to a continuous-valued label vector representing flare size or time-to-flare. When we consider flaring regions only, we find an average error in estimating flare size of approximately half a geostationary operational environmental satellite (GOES) class. When we additionally consider non-flaring regions, we find an increased average error of approximately three-fourths a GOES class. We also consider thresholding the regressed flare size for the experiment containing both flaring and non-flaring regions and find a true positive rate of 0.69 and a true negative rate of 0.86 for flare prediction. The results for both of these size regression experiments are consistent across a wide range of predictive time windows, indicating that the magnetic complexity features may be persistent in appearance long before flare activity. This is supported by our larger error rates of some 40 hr in the time-to-flare regression problem. The 38 magnetic complexity features considered here appear to have discriminative potential for flare size, but their persistence in time makes them less discriminative for the time-to-flare problem. Title: Too big to fail: The role of magnetic structure and dynamics in super active regions, on the Sun and Sun-like stars Authors: McAteer, R. T. James Bibcode: 2015IAUGA..2257122M Altcode: Accurate and timely solar activity forecasting has proved to be illusive. Despite many decades of research, we are not much further advanced in our forecasting efforts of the occurrence of solar activity than we were two decades ago. However, one aspect has become clear - big, complex magnetic active regions on the Sun inevitably produce big, complex solar flares and coronal mass ejections. Here, I present observations and models that show why these super active regions are too big to fail.First I focus on studies of the largest active regions of solar cycle 23 and 24, comparing proxies of non-potential magnetic structure in these regions with similar proxies in less active regions of the Sun. This shows that the necessary and sufficient conditions exist in these super active regions to provide both the largest solar flares and large, fast, coronal mass ejections.Second I show why these conditions in super active regions differ so dramatically from the conditions in smaller, less active, regions of the Sun. This uses magnetic feature tracking to infer the Poynting flux injected into the corona, and DEM analysis to provide radiative and conductive loss estimates from the corona. The difference between energy injected, and energy lost, is stored in the coronal magnetic field structure in the super active regions.Finally, I apply this this research to Kepler starspots , showing why these regions must differ in a fundamental way in order to overcome the limitations that super granular flow places on solar active regions formation and energy storage. Title: Coronal Seismology: Inferring Magnetic Fields and Exploring Damping Mechanisms Authors: McAteer, R. T. James; Ireland, Jack Bibcode: 2015IAUGA..2257620M Altcode: Recent observations in extreme ultra-violet wavelengths have shown that the solar corona oscillates at many different spatial sizes and temporal size scales. However, much remains unknown about many of these oscillations; they are intermittent for unknown reasons, appear on some coronal features and not on other, similar, neighboring features, and may (or may not) be magnetohydrodynamic (MHD) wave modes. Definitive causes of the structure and origins of these oscillations are still largely lacking. Here, we use automated oscillation detection routines to study a large sample of oscillations, inferring physical mechanisms as to how and why the corona varies.First, we measure the oscillation content of different physical regions on the Sun in SDO AIA data, using two different automated oscillation detection algorithms. This shows a power-law distribution in oscillatory frequency, disagreeing with strong historical assumptions about the nature of coronal heating and coronal seismology. We show how such disagreements can be reconciled by using a power-law background for oscillatory signals.Second we use coronal seismology to provide a means to infer coronal plasma parameters and to differentiate between potential damping mechanisms. Recent sets of kink-mode observations (usually 5-8 loops) have come insights into how the coronal is structured and how it evolves. We present a complex set of flare-induced, off-limb, coronal kink-mode oscillations of almost 100 loops. These display a spread of periods, amplitudes, and damping times, allowing us to probe the spatial distribution of these parameters for the first time. Both Fourier and Wavelet routines are used to automatically extract and characterize these oscillations. An initial period of P~500s, results in an inferred coronal magnetic field of B~20G. The decrease in the oscillation period of the loop position corresponds to a drop in number density inside the coronal loop, as predicted by MHD. As the the period drops below a threshold of P~300s, our MHD model cannot explain the sudden decrease in both period and density. A secondary dissipation mechanism must occur at this point in time and space. Title: Frozen Fractals all Around: Solar flares, Ampere’s Law, and the Search for Units in Scale-Free Processes. Authors: McAteer, R. T. James Bibcode: 2015IAUGA..2257411M Altcode: My soul is spiraling in frozen fractals all around, And one thought crystallizes like an icy blast, I'm never going back, the past is in the past.Elsa, from Disney’s Frozen, characterizes two fundamental aspects of scale-free processes in Nature: fractals are everywhere in space; fractals can be used to probe changes in time. Self-Organized Criticality provides a powerful set of tools to study scale-free processes. It connects spatial fractals (more generically, multifractals) to temporal evolution. The drawback is that this usually results in scale-free, unit-less, indices, which can be difficult to connect to everyday physics. Here, I show a novel method that connects one of the most powerful SOC tools - the wavelet transform modulus maxima approach to calculating multifractality - to one of the most powerful equations in all of physics - Ampere’s law. In doing so I show how the multifractal spectra can be expressed in terms of current density, and how current density can then be used for the prediction of future energy release from such a system.Our physical understanding of the solar magnetic field structure, and hence our ability to predict solar activity, is limited by the type of data currently available. I show that the multifractal spectrum provides a powerful physical connection between the details of photospheric magnetic gradients of current data and the coronal magnetic structure. By decomposing Ampere’s law and comparing it to the wavelet transform modulus maximum method, I show how the scale-free Holder exponent provides a direct measure of current density across all relevant sizes. The prevalence of this current density across various scales is connected to its stability in time, and hence to the ability of the magnetic structure to store and then release energy. Hence (spatial) multifractals inform us of (future) solar activity.Finally I discuss how such an approach can be used in any study of scale-free processes, and highlight the necessary key steps in identifying the nature of the mother wavelet to ensuring the viability of this powerful connection. Title: Active Region Morphologies Selected from Near-side Helioseismic Data Authors: MacDonald, G. A.; Henney, C. J.; Díaz Alfaro, M.; González Hernández, I.; Arge, C. N.; Lindsey, C.; McAteer, R. T. J. Bibcode: 2015ApJ...807...21M Altcode: We estimate the morphology of near-side active regions using near-side helioseismology. Active regions from two data sets, Air Force Data Assimilative Photospheric flux Transport synchronic maps and Global Oscillation Network Group near-side helioseismic maps, were matched and their morphologies compared. Our algorithm recognizes 382 helioseismic active regions between 2002 April 25 and 2005 December 31 and matches them to their corresponding magnetic active regions with 100% success. A magnetic active region occupies 30% of the area of its helioseismic signature. Recovered helioseismic tilt angles are in good agreement with magnetic tilt angles. Approximately 20% of helioseismic active regions can be decomposed into leading and trailing polarity. Leading polarity components show no discernible scaling relationship, but trailing magnetic polarity components occupy approximately 25% of the area of the trailing helioseismic component. A nearside phase-magnetic calibration is in close agreement with a previous far-side helioseismic calibration and provides confidence that these morphological relationships can be used with far-side helioseismic data. Including far-side active region morphology in synchronic maps will have implications for coronal magnetic topology predictions and solar wind forecasts. Title: An automated classification approach to ranking photospheric proxies of magnetic energy build-up Authors: Al-Ghraibah, A.; Boucheron, L. E.; McAteer, R. T. J. Bibcode: 2015A&A...579A..64A Altcode: 2015arXiv150608717A
Aims: We study the photospheric magnetic field of ~2000 active regions over solar cycle 23 to search for parameters that may be indicative of energy build-up and its subsequent release as a solar flare in the corona.
Methods: We extract three sets of parameters: (1) snapshots in space and time: total flux, magnetic gradients, and neutral lines; (2) evolution in time: flux evolution; and (3) structures at multiple size scales: wavelet analysis. This work combines standard pattern recognition and classification techniques via a relevance vector machine to determine (i.e., classify) whether a region is expected to flare (≥C1.0 according to GOES). We consider classification performance using all 38 extracted features and several feature subsets. Classification performance is quantified using both the true positive rate (the proportion of flares correctly predicted) and the true negative rate (the proportion of non-flares correctly classified). Additionally, we compute the true skill score which provides an equal weighting to true positive rate and true negative rate and the Heidke skill score to allow comparison to other flare forecasting work.
Results: We obtain a true skill score of ~0.5 for any predictive time window in the range 2 to 24 h, with a true positive rate of ~0.8 and a true negative rate of ~0.7. These values do not appear to depend on the predictive time window, although the Heidke skill score (<0.5) does. Features relating to snapshots of the distribution of magnetic gradients show the best predictive ability over all predictive time windows. Other gradient-related features and the instantaneous power at various wavelet scales also feature in the top five (of 38) ranked features in predictive power. It has always been clear that while the photospheric magnetic field governs the coronal non-potentiality (and hence likelihood of producing a solar flare), photospheric magnetic field information alone is not sufficient to determine this in a unique manner. Furthermore we are only measuring proxies of the magnetic energy build up. We are still lacking observational details on why energy is released at any particular point in time. We may have discovered the natural limit of the accuracy of flare predictions from these large scale studies. Title: Coronal Sources of the Solar F10.7 Radio Flux Authors: Schonfeld, S. J.; White, S. M.; Henney, C. J.; Arge, C. N.; McAteer, R. T. J. Bibcode: 2015ApJ...808...29S Altcode: 2015arXiv150800599S We present results from the first solar full-disk {{{F}}}10.7 (the radio flux at 10.7 cm, 2.8 GHz) image taken with the S-band receivers on the recently upgraded Karl G. Jansky Very Large Array in order to assess the relationship between the {{{F}}}10.7 index and solar extreme ultraviolet (EUV) emission. To identify the sources of the observed 2.8 GHz emission, we calculate differential emission measures from EUV images collected by the Atmospheric Imaging Assembly and use them to predict the bremsstrahlung component of the radio emission. By comparing the bremsstrahlung prediction and radio observation we find that 8.1% ± 0.5% of the variable component of the {{{F}}}10.7 flux is associated with the gyroresonance emission mechanism. Additionally, we identify optical depth effects on the radio limb which may complicate the use of {{{F}}}10.7 time series as an EUV proxy. Our analysis is consistent with a coronal iron abundance that is four times the photospheric level. Title: Frozen-in Fractals All Around: Inferring the Large-Scale Effects of Small-Scale Magnetic Structure Authors: McAteer, R. T. James Bibcode: 2015SoPh..290.1897M Altcode: 2015SoPh..tmp...87M; 2015arXiv150607914M The large-scale structure of the magnetic field in the solar corona provides the energy to power large-scale solar eruptive events. Our physical understanding of this structure, and hence our ability to predict these events, is limited by the type of data currently available. It is shown that the multifractal spectrum is a powerful tool to study this structure, by providing a physical connection between the details of photospheric magnetic gradients and current density at all size scales. This uses concepts associated with geometric measure theory and the theory of weakly differentiable functions to compare Ampère's law to the wavelet-transform modulus maximum method. The Hölder exponent provides a direct measure of the rate of change of current density across spatial size scales. As this measure is independent of many features of the data (pixel resolution, data size, data type, presence of quiet-Sun data), it provides a unique approach to studying magnetic-field complexity and hence a potentially powerful tool for a statistical prediction of solar-flare activity. Three specific predictions are provided to test this theory: the multifractal spectra will not be dependent on the data type or quality; quiet-Sun gradients will not persist with time; structures with high current densities at large size scales will be the source of energy storage for solar eruptive events. Title: Performance Testing of an Off-Limb Solar Adaptive Optics System Authors: Taylor, G. E.; Schmidt, D.; Marino, J.; Rimmele, T. R.; McAteer, R. T. J. Bibcode: 2015SoPh..290.1871T Altcode: 2015arXiv150801826T; 2015SoPh..tmp...54T Long-exposure spectro-polarimetry in the near-infrared is a preferred method to measure the magnetic field and other physical properties of solar prominences. In the past, it has been very difficult to observe prominences in this way with sufficient spatial resolution to fully understand their dynamical properties. Solar prominences contain highly transient structures, visible only at small spatial scales; hence they must be observed at sub-arcsecond resolution, with a high temporal cadence. An adaptive optics (AO) system capable of directly locking on to prominence structure away from the solar limb has the potential to allow for diffraction-limited spectro-polarimetry of solar prominences. We show the performance of the off-limb AO system and its expected performance at the desired science wavelength Ca II 8542 Å. Title: Coronal Fourier Power Spectra: Implications for Coronal Seismology and Coronal Heating Authors: Ireland, J.; McAteer, R. T. J.; Inglis, A. R. Bibcode: 2015ApJ...798....1I Altcode: 2014arXiv1410.2171I The dynamics of regions of the solar corona are investigated using Atmospheric Imaging Assembly 171 Å and 193 Å data. The coronal emission from the quiet Sun, coronal loop footprints, coronal moss, and from above a sunspot is studied. It is shown that the mean Fourier power spectra in these regions can be described by a power law at lower frequencies that tails to a flat spectrum at higher frequencies, plus a Gaussian-shaped contribution that varies depending on the region studied. This Fourier spectral shape is in contrast to the commonly held assumption that coronal time series are well described by the sum of a long timescale background trend plus Gaussian-distributed noise, with some specific locations also showing an oscillatory signal. The implications of the observed spectral shape on the fields of coronal seismology and the automated detection of oscillations in the corona are discussed. The power-law contribution to the shape of the Fourier power spectrum is interpreted as being due to the summation of a distribution of exponentially decaying emission events along the line of sight. This is consistent with the idea that the solar atmosphere is heated everywhere by small energy deposition events. Title: Qualities of Sequential Chromospheric Brightenings Observed in Hα and UV Images Authors: Kirk, Michael S.; Balasubramaniam, K. S.; Jackiewicz, Jason; McAteer, R. T. James Bibcode: 2014ApJ...796...78K Altcode: 2014arXiv1411.4069K Chromospheric flare ribbons observed in Hα appear well-organized when first examined: ribbons impulsively brighten, morphologically evolve, and exponentially decay back to pre-flare levels. Upon closer inspection of the Hα flares, there is often a significant number of compact areas brightening in concert with the flare eruption but are spatially separated from the evolving flare ribbon. One class of these brightenings is known as sequential chromospheric brightenings (SCBs). SCBs are often observed in the immediate vicinity of erupting flares and are associated with coronal mass ejections. In the past decade there have been several previous investigations of SCBs. These studies have exclusively relied upon Hα images to discover and analyze these ephemeral brightenings. This work employs the automated detection algorithm of Kirk et al. to extract the physical qualities of SCBs in observations of ground-based Hα images and complementary Atmospheric Imaging Assembly images in He II, C IV, and 1700 Å. The metadata produced in this tracking process are then culled using complementary Doppler velocities to isolate three distinguishable types of SCBs. From a statistical analysis, we find that the SCBs at the chromospheric Hα layer appear earlier and last longer than their corresponding signatures measured in AIA. From this multi-layer analysis, we infer that SCBs are spatially constrained to the mid-chromosphere. We also derive an energy budget to explain SCBs which have a postulated energy of not more than 0.01% of the total flare energy. Title: Coronal Fourier power spectra: implications for coronal heating and coronal seismology Authors: Ireland, J.; Mcateer, R. T. J.; Inglis, A. R. Bibcode: 2014AGUFMSH13C4128I Altcode: The dynamics of regions of the solar corona are investigated using AIA 171 and 193 Angstrom data. It is shown that the mean Fourier power spectra of emission from active region cores, above sunspots, in loop footpoints and in the quiet Sun, follow an approximate power-law behaviour. We show that power-law power-spectra can be formed by summing a distribution of exponentially decaying emission events along the line of sight, consistent with the idea that the corona is heated everywhere by small energy deposition events. We also examine changes in Fourier power spectrum as a function of coronal loop height to look for evidence of a preferred location to coronal heating. The observed power-law power spectra also have implications for coronal seismology, as all existing observational studies do not take into account the power-law power spectrum of the coronal emission and its attendant statistical properties. We show that random fluctuations in the emission can be mis-identified as oscillatory signal, and give suggestions on how to detect oscillatory motions above a background power-law power spectrum. Title: The Sources of F10.7 Emission Authors: Schonfeld, Samuel Joseph; White, S. M.; Henney, C. J.; McAteer, R. T. J.; Arge, C. N. Bibcode: 2014shin.confE..62S Altcode: The solar radio flux at a wavelength of 10.7 cm, F10.7, serves as a proxy for the Sun"s ionizing flux striking the Earth and is a heavily used index for space weather studies. In principal both the coronal sources of ionizing flux and strong coronal magnetic fields contribute to F10.7 via different emission mechanisms. Recently the Karl G. Jansky Very Large Array (VLA) has added the capability to make high-spatial-resolution images of the Sun at 10.7 cm. In this work we compare a trial F10.7 image from the VLA with the radio emission predicted to be present from EUV images of the Sun acquired by the AIA telescope on the Solar Dynamics Observatory at 6 wavelengths covering the coronal temperature range. Photospheric magnetograms are used to identify likely regions of strong coronal magnetic field, and the circular polarization measured by the VLA is used as a tracer of gyroresonance contributions to F10.7. We discuss the conversion of the EUV data to bremsstrahlung radio fluxes via the construction of differential emission measure images, and analyze the relative contributions of the different sources of F10.7 flux. Title: Power Spectra in AIA 171 and 193 and Their Implications for Coronal Seismology Authors: Ireland, Jack; Mcateer, Robert TJ; Inglis, Andrew Bibcode: 2014AAS...22432321I Altcode: We examine Fourier power spectra of time-series of AIA 171 and 193 waveband data. We show that these power spectra exhibit a red-noise like power-law behaviour on time-scales of interest to coronal seismology. We show that assuming a white noise background power spectrum when a red-noise power spectrum is present can lead to the mistaken identification of narrow-band oscillatory power when none is present. Thisimplies that a background power-law power spectrum must be taken in to account when determining the presence of narrow-band oscillations that may be due to MHD wave processes in the solar corona. We also show that the red-noise power spectrum is consistent with the expected power spectrum from large number of exponentially decaying emission events with event size taken from a power law distribution. Title: On the Sensitivity of the GOES Flare Classification to Properties of the Electron Beam in the Thick-target Model Authors: Reep, J. W.; Bradshaw, S. J.; McAteer, R. T. J. Bibcode: 2013ApJ...778...76R Altcode: 2013arXiv1310.3242R The collisional thick-target model, wherein a large number of electrons are accelerated down a flaring loop, can be used to explain many observed properties of solar flares. In this study, we focus on the sensitivity of (GOES) flare classification to the properties of the thick-target model. Using a hydrodynamic model with RHESSI-derived electron beam parameters, we explore the effects of the beam energy flux (or total non-thermal energy), the cut-off energy, and the spectral index of the electron distribution on the soft X-rays observed by GOES. We conclude that (1) the GOES class is proportional to the non-thermal energy E α for α ≈ 1.7 in the low-energy passband (1-8 Å) and ≈1.6 in the high-energy passband (0.5-4 Å) (2) the GOES class is only weakly dependent on the spectral index in both passbands; (3) increases in the cut-off will increase the flux in the 0.5-4 Å passband but decrease the flux in the 1-8 Å passband, while decreases in the cut-off will cause a decrease in the 0.5-4 Å passband and a slight increase in the 1-8 Å passband. Title: The Bursty Nature of Solar Flare X-Ray Emission. II. The Neupert Effect Authors: McAteer, R. T. James; Bloomfield, D. Shaun Bibcode: 2013ApJ...776...66M Altcode: We carry out a novel statistical test of the Neupert effect based on multifractal spectra. The multifractal spectrum is the number distribution of the strengths (i.e., the Hölder exponents) of bursts in a signal. This is tested on simulations and carried out on RHESSI X-ray data from a well observed GOES X4.8 magnitude flare. The multifractal spectra is ideally suited to quantifying the relative smooth and bursty signals typically found in (thermal) soft X-ray and (non-thermal) hard X-ray data of solar flares. We show that light curves from all energies between 3 keV and 25 keV are statistically similar, suggesting that all these signals are dominated by the same (presumably thermal) emission. Emission lying between 25 keV and 100 keV probably contains some contribution from both thermal and non-thermal sources. The multifractal spectrum of a signal and that of its (cumulative) temporal integration are statistically similar (i.e., low residuals upon subtraction), but shifted by one in the peak Hölder exponent. We find the pairs of 3-6 keV and 100-300 keV emissions, the 6-12 keV and 100-300 keV emissions and the 12-25 keV and 100-300 keV emissions are all consistent with the Neupert effect. The best agreement with the Neupert effect is between the 12-25 keV and 100-300 keV pair, although possibly with some secondary source of thermal emission present. Title: Oscillatory Behavior in the Corona Authors: Calabro, B.; McAteer, R. T. J.; Bloomfield, D. S. Bibcode: 2013SoPh..286..405C Altcode: We detect and analyze the oscillatory behavior of waves using a coronal seismology tool on sequences of coronal images. We study extreme-ultraviolet image sequences of active and quiet Sun regions and of coronal holes we identify 3- and 5-minute periodicities. In each studied region the 3- and 5-minute periodicities are similarly frequent. The number of pixels exhibiting a 3-minute periodicity is between 6 % - 8 % and those pixels exhibiting a 5-minute periodicity is between 5 % - 9 % of the total number of observed pixels. Our results show 3-minute oscillations along coronal loop structures but do not show 5-minute oscillations along these same loop structures. The number of pixels exhibiting 3- and 5-minute periodicities in one type of region (active Sun, quiet Sun, and coronal holes) is roughly the same for all observed regions, leading us to infer that the 3- and 5-minute oscillations are the result of a global mechanism. Title: Improved methods for determining the kinematics of coronal mass ejections and coronal waves Authors: Byrne, J. P.; Long, D. M.; Gallagher, P. T.; Bloomfield, D. S.; Maloney, S. A.; McAteer, R. T. J.; Morgan, H.; Habbal, S. R. Bibcode: 2013A&A...557A..96B Altcode: 2013arXiv1307.8155B Context. The study of solar eruptive events and associated phenomena is of great importance in the context of solar and heliophysics. Coronal mass ejections (CMEs) and coronal waves are energetic manifestations of the restructuring of the solar magnetic field and mass motion of the plasma. Characterising this motion is vital for deriving the dynamics of these events and thus understanding the physics driving their initiation and propagation. The development and use of appropriate methods for measuring event kinematics is therefore imperative.
Aims: Traditional approaches to the study of CME and coronal wave kinematics do not return wholly accurate nor robust estimates of the true event kinematics and associated uncertainties. We highlight the drawbacks of these approaches, and demonstrate improved methods for accurate and reliable determination of the kinematics.
Methods: The Savitzky-Golay filter is demonstrated as a more appropriate fitting technique for CME and coronal wave studies, and a residual resampling bootstrap technique is demonstrated as a statistically rigorous method for the determination of kinematic error estimates and goodness-of-fit tests.
Results: It is shown that the scatter on distance-time measurements of small sample size can significantly limit the ability to derive accurate and reliable kinematics. This may be overcome by (i) increasing measurement precision and sampling cadence; and (ii) applying robust methods for deriving the kinematics and reliably determining their associated uncertainties. If a priori knowledge exists and a pre-determined model form for the kinematics is available (or indeed any justified fitting-form to be tested against the data), then its precision can be examined using a bootstrapping technique to determine the confidence interval associated with the model/fitting parameters.
Conclusions: Improved methods for determining the kinematics of CMEs and coronal waves are demonstrated to great effect, overcoming many issues highlighted in traditional numerical differencing and error propagation techniques. Title: The sensitivity of GOES flare classification to the thick-target model Authors: Reep, Jeffrey; Bradshaw, S.; Mcateer, R. T. Bibcode: 2013SPD....44...59R Altcode: The collisional thick-target model has been used to explain many spectral features of solar flares. Flare classification, based on soft X-rays observed by GOES, should then depend on the model. Using a combination of numerical simulations and observed features of flares, we explore the sensitivity of flare classification to the parameters of the thick-target model. We vary the total non-thermal energy, spectral index, and the cut-off energy of the electron beam one at a time for two sets of parameters derived from flares observed with RHESSI. We find that the classification depends strongly on non-thermal energy, only weakly on spectral index, and that the cut-off energy can either increase or decrease the GOES class, depending upon how it varies. Title: On the sensitivity of GOES flare classification to the collisional thick-target model Authors: Reep, Jeffrey; Bradshaw, S.; Mcateer, R. T. Bibcode: 2013SPD....44...62R Altcode: The collisional thick-target model has been used to explain many spectral features of solar flares. Flare classification, based on soft X-rays observed by GOES, should then depend on the model. Using a combination of numerical simulations and observed features of flares, we explore the sensitivity of flare classification to the parameters of the thick-target model. We vary the total non-thermal energy, spectral index, and the cut-off energy of the electron beam one at a time for two sets of parameters derived from flares observed with RHESSI. We find that the classification depends strongly on non-thermal energy, only weakly on spectral index, and that the cut-off energy can either increase or decrease the GOES class, depending upon how it varies. Title: Remote Oscillatory Responses to a Solar Flare Authors: And¯ić, A.; McAteer, R. T. J. Bibcode: 2013ApJ...772...54A Altcode: The processes governing energy storage and release in the Sun are both related to the solar magnetic field. We demonstrate the existence of a magnetic connection between the energy released by a flare and increased oscillatory power in the lower solar atmosphere. The oscillatory power in active regions tends to increase in response to explosive events at other locations, but not in the active region itself. We carry out timing studies and show that this effect is probably caused by a large-scale magnetic connection between the regions, instead of a globally-propagating wave. We show that oscillations tend to exist in longer-lived wave trains with short periods (P < 200 s) at the time of a flare. These wave trains may be mechanisms by which flare energy can be redistributed throughout the solar atmosphere. Title: Remote Oscillatory responses to a solar flare Authors: Andic, Aleksandra; McAteer, R. T. James Bibcode: 2013arXiv1306.3475A Altcode: The processes governing energy storage and release in the Sun are both related to the solar magnetic field. We demonstrate the existence of a magnetic connection between energy released caused by a flare and increased oscillatory power in the lower solar atmosphere. The oscillatory power in active regions tends to increase in response to explosive events at a different location, but not in the region itself. We carry out timing studies and show that this is probably caused by a large scale magnetic connection between the regions, and not a globally propagating wave. We show that oscillations tend to exist in longer lived wave trains at short periods (P< 200s) at the time of a flare. This may be a mechanism by which flare energy can be redistributed throughout the solar atmosphere. Title: SOC and Fractal Geometry Authors: McAteer, R. T. J. Bibcode: 2013socs.book...73M Altcode: When Mandelbrot, the father of modern fractal geometry, made this seemingly obvious statement he was trying to show that we should move out of our comfortable Euclidean space and adopt a fractal approach to geometry. The concepts and mathematical tools of fractal geometry provides insight into natural physical systems that Euclidean tools cannot do. The benet from applying fractal geometry to studies of Self-Organized Criticality (SOC) are even greater. SOC and fractal geometry share concepts of dynamic n-body interactions, apparent non-predictability, self-similarity, and an approach to global statistics in space and time that make these two areas into naturally paired research techniques. Further, the iterative generation techniques used in both SOC models and in fractals mean they share common features and common problems. This chapter explores the strong historical connections between fractal geometry and SOC from both a mathematical and conceptual understanding, explores modern day interactions between these two topics, and discusses how this is likely to evolve into an even stronger link in the near future. Title: Flares, waves, and energy Authors: Andic, A.; McAteer, R. T. J.; McNamara, B. Bibcode: 2013enss.confE...2A Altcode: Solar energy storage and release events are interconnected. This research addresses one aspect of the interconnection of those energetic solar events. Addressed aspect emerged in recent research that showed a movement of a flux tubes generates oscillations. Analysis was performed using six C class and one M class flares during Dec. 25, 2011. Using AIA and HMI data, we investigated the connection between flare induced disturbance and changes in the flux of photospheric oscillations. Results showed significant increase of oscillatory flux following the flare itself. This increase was detected outside of flare location. Results show a need for deeper statistical analysis of the oscillatory response at flare induced disturbance. This kind of analysis might reveal energy distributions when this aspect of interconnection is in question. Title: An Automated Algorithm to Distinguish and Characterize Solar Flares and Associated Sequential Chromospheric Brightenings Authors: Kirk, M. S.; Balasubramaniam, K. S.; Jackiewicz, J.; McNamara, B. J.; McAteer, R. T. J. Bibcode: 2013SoPh..283...97K Altcode: 2011arXiv1108.1384K; 2011SoPh..tmp..345K We present a new automated algorithm to identify, track, and characterize small-scale brightening associated with solar eruptive phenomena observed in Hα. The temporal, spatially localized changes in chromospheric intensities can be separated into two categories: flare ribbons and sequential chromospheric brightenings (SCBs). Within each category of brightening we determine the smallest resolvable locus of pixels, a kernel, and track the temporal evolution of the position and intensity of each kernel. This tracking is accomplished by isolating the eruptive features, identifying kernels, and linking detections between frames into trajectories of kernels. We fully characterize the evolving intensity and morphology of the flare ribbons by observing the tracked flare kernels in aggregate. With the location of SCB and flare kernels identified, they can easily be overlaid on complementary data sets to extract Doppler velocities and magnetic-field intensities underlying the kernels. This algorithm is adaptable to any dataset to identify and track solar features. Title: Solar Limb Adaptive Optics: A Test of Wavefront Sensors and Algorithms Authors: Taylor, G. E.; Rimmele, T. R.; Marino, J.; Tritschler, A.; McAteer, R. T. J. Bibcode: 2012ASPC..463..321T Altcode: In order to advance our understanding of solar prominences, we need to be able to observe them at high spatial, spectral and temporal resolution. In order to determine physical properties of these cool and faint coronal structures, however, one is forced to use long exposure times, particularly in spectroscopic and spectropolarimetric applications. It is thus crucial that image stabilization is provided, preferrably in form of an adaptive optics (AO) system that is capable to lock onto the off-limb prominence structure, potentially providing diffraction limited imaging. We investigate the preliminary design of such a solar-limb AO system based on a correlating Shack-Hartmann sensor. As an alternative we also studied a solar-limb AO wavefront sensor using a phase-diverse approach. Title: Sequential Chomospheric Brightening: An Automated Approach to Extracting Physics from Ephemeral Brightening Authors: Kirk, M. S.; Balasubramaniam, K. S.; Jackiewicz, J.; McAteer, R. T. J.; McNamara, B. J. Bibcode: 2012ASPC..463..267K Altcode: 2012arXiv1203.1277K We make a comparison between small scale chromospheric brightenings and energy release processes through examining the temporal evolution of sequential chromospheric brightenings (SCBs), derive propagation velocities, and propose a connection of the small-scale features to solar flares. Our automated routine detects and distinguishes three separate types of brightening regularly observed in the chromosphere: plage, flare ribbon, and point brightenings. By studying their distinct dynamics, we separate out the flare-associated bright points commonly known as SCBs and identify a propagating Moreton wave. Superimposing our detections on complementary off-band images, we extract a Doppler velocity measurement beneath the point brightening locations. Using these dynamic measurements, we put forward a connection between point brightenings, the erupting flare, and overarching magnetic loops. A destabilization of the pre-flare loop topology by the erupting flare directly leads to the SCBs observed. Title: Observations of Low Frequency Solar Radio Bursts from the Rosse Solar-Terrestrial Observatory Authors: Zucca, P.; Carley, E. P.; McCauley, J.; Gallagher, P. T.; Monstein, C.; McAteer, R. T. J. Bibcode: 2012SoPh..280..591Z Altcode: 2012SoPh..tmp...94Z; 2012arXiv1204.0943Z The Rosse Solar-Terrestrial Observatory (RSTO; www.rosseobservatory.ie) was established at Birr Castle, Co. Offaly, Ireland (53°05'38.9″, 7°55'12.7″) in 2010 to study solar radio bursts and the response of the Earth's ionosphere and geomagnetic field. To date, three Compound Astronomical Low-cost Low-frequency Instrument for Spectroscopy in Transportable Observatory (CALLISTO) spectrometers have been installed, with the capability of observing in the frequency range of 10 - 870 MHz. The receivers are fed simultaneously by biconical and log-periodic antennas. Nominally, frequency spectra in the range of 10 - 400 MHz are obtained with four sweeps per second over 600 channels. Here, we describe the RSTO solar radio spectrometer set-up, and present dynamic spectra of samples of type II, III and IV radio bursts. In particular, we describe the fine-scale structure observed in type II bursts, including band splitting and rapidly varying herringbone features. Title: Coronal Mass Ejection Mass, Energy, and Force Estimates Using STEREO Authors: Carley, Eoin P.; McAteer, R. T. James; Gallagher, Peter T. Bibcode: 2012ApJ...752...36C Altcode: 2012arXiv1204.4601C Understanding coronal mass ejection (CME) energetics and dynamics has been a long-standing problem, and although previous observational estimates have been made, such studies have been hindered by large uncertainties in CME mass. Here, the two vantage points of the Solar Terrestrial Relations Observatory (STEREO) COR1 and COR2 coronagraphs were used to accurately estimate the mass of the 2008 December 12 CME. Acceleration estimates derived from the position of the CME front in three dimensions were combined with the mass estimates to calculate the magnitude of the kinetic energy and driving force at different stages of the CME evolution. The CME asymptotically approaches a mass of 3.4 ± 1.0 × 1015 g beyond ~10 R . The kinetic energy shows an initial rise toward 6.3 ± 3.7 × 1029 erg at ~3 R , beyond which it rises steadily to 4.2 ± 2.5 × 1030 erg at ~18 R . The dynamics are described by an early phase of strong acceleration, dominated by a force of peak magnitude of 3.4 ± 2.2 × 1014 N at ~3 R , after which a force of 3.8 ± 5.4 × 1013 N takes effect between ~7 and 18 R . These results are consistent with magnetic (Lorentz) forces acting at heliocentric distances of lsim7 R , while solar wind drag forces dominate at larger distances (gsim7 R ). Title: Properties of Sequential Chromospheric Brightenings and Associated Flare Ribbons Authors: Kirk, Michael S.; Balasubramaniam, K. S.; Jackiewicz, Jason; McAteer, R. T. James; Milligan, Ryan O. Bibcode: 2012ApJ...750..145K Altcode: 2012arXiv1203.1271K We report on the physical properties of solar sequential chromospheric brightenings (SCBs) observed in conjunction with moderate-sized chromospheric flares with associated Coronal mass ejections. To characterize these ephemeral events, we developed automated procedures to identify and track subsections (kernels) of solar flares and associated SCBs using high-resolution Hα images. Following the algorithmic identification and a statistical analysis, we compare and find the following: SCBs are distinctly different from flare kernels in their temporal characteristics of intensity, Doppler structure, duration, and location properties. We demonstrate that flare ribbons are themselves made up of subsections exhibiting differing characteristics. Flare kernels are measured to have a mean propagation speed of 0.2 km s-1 and a maximum speed of 2.3 km s-1 over a mean distance of 5 × 103 km. Within the studied population of SCBs, different classes of characteristics are observed with coincident negative, positive, or both negative and positive Doppler shifts of a few km s-1. The appearance of SCBs precedes peak flare intensity by ≈12 minutes and decay ≈1 hr later. They are also found to propagate laterally away from flare center in clusters at 45 km s-1 or 117 km s-1. Given SCBs' distinctive nature compared to flares, we suggest a different physical mechanism relating to their origin than the associated flare. We present a heuristic model of the origin of SCBs. Title: An Insight Into Atmospheric Structure Through Compact Chromospheric Brightenings Authors: Kirk, Michael S.; Balasubramaniam, K.; Jackiewicz, J.; McAteer, R. Bibcode: 2012AAS...22012406K Altcode: Compact chromospheric brightenings have a range of intensities, Doppler velocities, and magnetic field strength each giving clues to their physical origin. One type of compact brightening, sequential chromospheric brightening (SCB), has several properties of small-scale chromospheric evaporation. SCBs appear adjacent to two ribbon flares with associated halo CMEs. This work presents a definition of SCBs constrained by a statistical analysis of several chromospheric flaring events. From this definition of SCBs, we extract physical qualities of SCBs and correlate these qualities with data gathered from additional layers of the solar atmosphere. Using these dynamic measurements, we suggest a connection between compact brightenings, the erupting flare, and overarching magnetic loops. Title: Waves and Flares Authors: Andic, Aleksandra; McAteer, R.; Jackiewicz, J.; Boucheron, L.; Cao, H.; McNamara, B. Bibcode: 2012AAS...22052109A Altcode: It has been demonstrated that movement of the flux tube can cause oscillations (Andic et al. 2010). In this work we present preliminary research that shows what happens with the oscillations before, during, and after magnetic field reconfigurations caused by explosive events. We detect oscillations at locations where the magnetic field touches the photosphere. However, we plan to analyze a larger statistical sample of flaring active region to better quantify the relation between these oscillations and movement of flux tubes caused by disturbances in the magnetic field. Title: Toward Reliable Benchmarking of Solar Flare Forecasting Methods Authors: Bloomfield, D. Shaun; Higgins, Paul A.; McAteer, R. T. James; Gallagher, Peter T. Bibcode: 2012ApJ...747L..41B Altcode: 2012arXiv1202.5995B Solar flares occur in complex sunspot groups, but it remains unclear how the probability of producing a flare of a given magnitude relates to the characteristics of the sunspot group. Here, we use Geostationary Operational Environmental Satellite X-ray flares and McIntosh group classifications from solar cycles 21 and 22 to calculate average flare rates for each McIntosh class and use these to determine Poisson probabilities for different flare magnitudes. Forecast verification measures are studied to find optimum thresholds to convert Poisson flare probabilities into yes/no predictions of cycle 23 flares. A case is presented to adopt the true skill statistic (TSS) as a standard for forecast comparison over the commonly used Heidke skill score (HSS). In predicting flares over 24 hr, the maximum values of TSS achieved are 0.44 (C-class), 0.53 (M-class), 0.74 (X-class), 0.54 (>=M1.0), and 0.46 (>=C1.0). The maximum values of HSS are 0.38 (C-class), 0.27 (M-class), 0.14 (X-class), 0.28 (>=M1.0), and 0.41 (>=C1.0). These show that Poisson probabilities perform comparably to some more complex prediction systems, but the overall inaccuracy highlights the problem with using average values to represent flaring rate distributions. Title: Computer Vision for the Solar Dynamics Observatory (SDO) Authors: Martens, P. C. H.; Attrill, G. D. R.; Davey, A. R.; Engell, A.; Farid, S.; Grigis, P. C.; Kasper, J.; Korreck, K.; Saar, S. H.; Savcheva, A.; Su, Y.; Testa, P.; Wills-Davey, M.; Bernasconi, P. N.; Raouafi, N. -E.; Delouille, V. A.; Hochedez, J. F.; Cirtain, J. W.; DeForest, C. E.; Angryk, R. A.; De Moortel, I.; Wiegelmann, T.; Georgoulis, M. K.; McAteer, R. T. J.; Timmons, R. P. Bibcode: 2012SoPh..275...79M Altcode: 2011SoPh..tmp..144M; 2011SoPh..tmp..213M; 2011SoPh..tmp....8M In Fall 2008 NASA selected a large international consortium to produce a comprehensive automated feature-recognition system for the Solar Dynamics Observatory (SDO). The SDO data that we consider are all of the Atmospheric Imaging Assembly (AIA) images plus surface magnetic-field images from the Helioseismic and Magnetic Imager (HMI). We produce robust, very efficient, professionally coded software modules that can keep up with the SDO data stream and detect, trace, and analyze numerous phenomena, including flares, sigmoids, filaments, coronal dimmings, polarity inversion lines, sunspots, X-ray bright points, active regions, coronal holes, EIT waves, coronal mass ejections (CMEs), coronal oscillations, and jets. We also track the emergence and evolution of magnetic elements down to the smallest detectable features and will provide at least four full-disk, nonlinear, force-free magnetic field extrapolations per day. The detection of CMEs and filaments is accomplished with Solar and Heliospheric Observatory (SOHO)/Large Angle and Spectrometric Coronagraph (LASCO) and ground-based Hα data, respectively. A completely new software element is a trainable feature-detection module based on a generalized image-classification algorithm. Such a trainable module can be used to find features that have not yet been discovered (as, for example, sigmoids were in the pre-Yohkoh era). Our codes will produce entries in the Heliophysics Events Knowledgebase (HEK) as well as produce complete catalogs for results that are too numerous for inclusion in the HEK, such as the X-ray bright-point metadata. This will permit users to locate data on individual events as well as carry out statistical studies on large numbers of events, using the interface provided by the Virtual Solar Observatory. The operations concept for our computer vision system is that the data will be analyzed in near real time as soon as they arrive at the SDO Joint Science Operations Center and have undergone basic processing. This will allow the system to produce timely space-weather alerts and to guide the selection and production of quicklook images and movies, in addition to its prime mission of enabling solar science. We briefly describe the complex and unique data-processing pipeline, consisting of the hardware and control software required to handle the SDO data stream and accommodate the computer-vision modules, which has been set up at the Lockheed-Martin Space Astrophysics Laboratory (LMSAL), with an identical copy at the Smithsonian Astrophysical Observatory (SAO). Title: Chromospheric Explosions: Linking Observations Toward a Physical Model Authors: Kirk, Michael S.; Balasubramaniam, K. S.; Jackiewicz, J.; McAteer, R. T. J.; McNamara, B. J. Bibcode: 2012AAS...21922408K Altcode: Bright points are observed routinely in every layer of the Sun. One type of bright point, called sequential chromospheric brightening (SCB), is coincident with flares and is thought to represent a chromospheric foot-point of a magnetic field line that extends into the corona. These field lines are energized during a CME-causing eruption leading to the brightening we observe. We extract physical measurements of chromospheric flares and SCBs using an automated feature detection suite. Correlating these results with complementary data from the corona, we identify the spatio-temporal relationship between coronal loops and SCBs. We explore a coronal origin for SCBs and put forth an explicatory model. Title: Automated Classification of Flaring Behavior in Solar Active Regions: Preliminary Results Authors: Al-Ghraibah, Amani; Boucheron, L. E.; McAteer, R.; Cao, H.; Jackiewicz, J.; McNamara, B.; Voelz, D.; Calabro, B.; DeGrave, K.; Hao, Y.; Kirk, M.; Pevtsov, A.; Mckeever, J.; Taylor, G. Bibcode: 2012AAS...21914516A Altcode: Solar active events are the source of many energetic and geo-effective events such as solar flares and coronal mass ejections (CMEs). Understanding how these complex source regions evolve and produce these events is of fundamental importance, not only to solar physics but also the demands of space weather forecasting. In this poster, we present preliminary results from our analysis of the physical properties of active region magnetic fields using fractal-, gradient-, neutral line-, emerging flux-, and wavelet-based techniques. These analyses look to use the defined physical measures to form a predictive model for flaring behavior in active regions. Title: Coronal Loop Detection and Seismology Authors: Pevtsov, Alexander; McAteer, R. T. J.; Jackiewicz, J.; McNamara, B.; Kirk, M.; Degrave, K.; Boucheron, L.; Calabro, B. Bibcode: 2012AAS...21914405P Altcode: We study the spatial distribution and temporal evolution of coronal loops using data from the Solar Dynamics Observatory (SDO) Atmospheric Imaging Assembly (AIA). We apply an automated coronal loop detection algorithm that is maximized for accuracy and completeness, and reconnects orphaned segments of coronal loops, to extreme ultraviolet images of the solar corona. We quantify the loop size distribution with a scaling index in each of the SDO AIA passbands, and show how this changes with time. This provides new insights into the physical mechanisms that create coronal structure. Title: Multifractality, magnetic fields, and solar eruptive events Authors: Mcateer, R. Bibcode: 2011AGUFMSH43E..04M Altcode: Solar flares and coronal mass ejections are among the most energetic events in the solar system. These events occur in active regions in the solar corona, formed through the convective action of subsurface fluid motions pushing magnetic flux tubes through the Sun's surface, the photosphere. It has long been recognized that through characterizing active region magnetic field complexity we can begin to understand which active region properties are important indicators of solar eruptive events. We show that two such complexity measures, the multifractal spectrum and the multiscale turbulence spectrum, have enormous potential for the prediction of these events in a accurate and timely manner. Furthermore we show that they are directly related to physical measurements of field gradients and flux emergence, thereby allowing a cross calibration of unitless SOC measures to the distribution of measures with physical units. Title: Mapping the Dynamics of Chromospheric Flares Authors: Kirk, M. S.; Balasubramaniam, K. S.; Jackiewicz, J.; Mcateer, R. Bibcode: 2011AGUFMSH51B2003K Altcode: Brightening in the chromosphere comes in three different flavors: plage, flare ribbon, and point. These types of brightening are all characterized by intensity above the background but have different dynamics causing the increased intensity. We have developed an automated software suite to identify and track both ribbon and point brightening associated with moderate sized flares observed in H alpha. Superposing our detections on complementary datasets, we produce a three-dimensional velocity map of flare ribbons, and a Doppler velocity measurement beneath the point brightening detections. These dynamic measurements allow us to postulate a physical connection between point brightening, the erupting flare, and coronal loops. Title: Deceleration and dispersion of large-scale coronal bright fronts Authors: Long, D. M.; Gallagher, P. T.; McAteer, R. T. J.; Bloomfield, D. S. Bibcode: 2011A&A...531A..42L Altcode: 2011arXiv1104.4334L Context. One of the most dramatic manifestations of solar activity are large-scale coronal bright fronts (CBFs) observed in extreme ultraviolet (EUV) images of the solar atmosphere. To date, the energetics and kinematics of CBFs remain poorly understood, due to the low image cadence and sensitivity of previous EUV imagers and the limited methods used to extract the features.
Aims: In this paper, the trajectory and morphology of CBFs was determined in order to investigate the varying properties of a sample of CBFs, including their kinematics and pulse shape, dispersion, and dissipation.
Methods: We have developed a semi-automatic intensity profiling technique to extract the morphology and accurate positions of CBFs in 2.5-10 min cadence images from STEREO/EUVI. The technique was applied to sequences of 171 Å and 195 Å images from STEREO/EUVI in order to measure the wave properties of four separate CBF events.
Results: Following launch at velocities of ~240-450 km s-1 each of the four events studied showed significant negative acceleration ranging from ~-290 to -60 m s-2. The CBF spatial and temporal widths were found to increase from ~50 Mm to ~200 Mm and ~100 s to ~1500 s respectively, suggesting that they are dispersive in nature. The variation in position-angle averaged pulse-integrated intensity with propagation shows no clear trend across the four events studied. These results are most consistent with CBFs being dispersive magnetoacoustic waves.

Figures 3-8, 10, 11, 13-15, 17, 18 and the movie are available in electronic form at http://www.aanda.org Title: Solar magnetic feature detection and tracking for space weather monitoring Authors: Higgins, P. A.; Gallagher, P. T.; McAteer, R. T. J.; Bloomfield, D. S. Bibcode: 2011AdSpR..47.2105H Altcode: 2010arXiv1006.5898H We present an automated system for detecting, tracking, and cataloging emerging active regions throughout their evolution and decay using SOHO Michelson Doppler Interferometer (MDI) magnetograms. The SolarMonitor Active Region Tracking (SMART) algorithm relies on consecutive image differencing to remove both quiet-Sun and transient magnetic features, and region-growing techniques to group flux concentrations into classifiable features. We determine magnetic properties such as region size, total flux, flux imbalance, flux emergence rate, Schrijver’s R-value, R (a modified version of R), and Falconer’s measurement of non-potentiality. A persistence algorithm is used to associate developed active regions with emerging flux regions in previous measurements, and to track regions beyond the limb through multiple solar rotations. We find that the total number and area of magnetic regions on disk vary with the sunspot cycle. While sunspot numbers are a proxy to the solar magnetic field, SMART offers a direct diagnostic of the surface magnetic field and its variation over timescale of hours to years. SMART will form the basis of the active region extraction and tracking algorithm for the Heliophysics Integrated Observatory (HELIO). Title: Coronal mass ejection detection using wavelets, curvelets and ridgelets: Applications for space weather monitoring Authors: Gallagher, P. T.; Young, C. A.; Byrne, J. P.; McAteer, R. T. J. Bibcode: 2011AdSpR..47.2118G Altcode: 2010arXiv1012.1901G Coronal mass ejections (CMEs) are large-scale eruptions of plasma and magnetic field that can produce adverse space weather at Earth and other locations in the Heliosphere. Due to the intrinsic multiscale nature of features in coronagraph images, wavelet and multiscale image processing techniques are well suited to enhancing the visibility of CMEs and suppressing noise. However, wavelets are better suited to identifying point-like features, such as noise or background stars, than to enhancing the visibility of the curved form of a typical CME front. Higher order multiscale techniques, such as ridgelets and curvelets, were therefore explored to characterise the morphology (width, curvature) and kinematics (position, velocity, acceleration) of CMEs. Curvelets in particular were found to be well suited to characterising CME properties in a self-consistent manner. Curvelets are thus likely to be of benefit to autonomous monitoring of CME properties for space weather applications. Title: Solar Oscillations And Acoustic Power Measured In H-alpha Authors: Jackiewicz, Jason; Balasubramaniam, K.; McAteer, R.; Jefferies, S. M. Bibcode: 2011SPD....42.1731J Altcode: 2011BAAS..43S.1731J We present initial studies of the evidence of acoustic power in H alpha data observed with the ISOON telescope. Uninterrupted times series were obtained at 1-minute cadence of the H alpha intensity and Doppler velocity signals of both quiet and active regions on the Sun. Spatial and temporal power maps show enhanced contributions from a flaring active region that is a strong function of frequency. Cross-correlations and wave travel times are computed and give indications of the presence of running waves below the acoustic cut-off frequency. Title: Coronal Loop detection and seismology Authors: Pevtsov, Alexander; McAteer, R. T. J.; Jackiewicz, J.; Kirk, M.; McNamara, B.; DeGrave, K.; Amani Al-Ghraibah, A.; Boucheron, L.; Voelz, D.; Cao, H.; Taylor, G. Bibcode: 2011SPD....42.1822P Altcode: 2011BAAS..43S.1822P Using a TRACE image with a bipolar active region and over one hundred distinguishable loops, we examine several current methods for automated coronal loop detection. Using the same TRACE image, several new approaches are also taken in an attempt to increase accuracy and completeness rates for the automated detection process. By means of these new methods the expectation is to achieve a higher degree of completeness while maintaining a high level of accuracy in the detection process. To increase completeness, an automated attempt for the reconnection between orphaned loop segments will also be tested. In the future, an approach to reconstruction of three-dimensional images from several two-dimensional images can be devised by using the detected coronal loops and a known 3D offset of each image. However this process heavily depends on the ability to accurately and completely detect the coronal loops. Title: Automated Solar Feature Detection for Space Weather Applications Authors: Pérez-Suárez, David; Higgins, Paul A.; Bloomfield, D. Shaun; McAteer, R. T. James; Krista, Larisza D.; Byrne, Jason P.; Gallagher, Peter. T. Bibcode: 2011asip.book..207P Altcode: 2011arXiv1109.6922P The solar surface and atmosphere are highly dynamic plasma environments, which evolve over a wide range of temporal and spatial scales. Large-scale eruptions, such as coronal mass ejections, can be accelerated to millions of kilometres per hour in a matter of minutes, making their automated detection and characterisation challenging. Additionally, there are numerous faint solar features, such as coronal holes and coronal dimmings, which are important for space weather monitoring and forecasting, but their low intensity and sometimes transient nature makes them problematic to detect using traditional image processing techniques. These difficulties are compounded by advances in ground- and space- based instrumentation, which have increased the volume of data that solar physicists are confronted with on a minute-by-minute basis; NASA's Solar Dynamics Observatory for example is returning many thousands of images per hour (~1.5 TB/day). This chapter reviews recent advances in the application of images processing techniques to the automated detection of active regions, coronal holes, filaments, CMEs, and coronal dimmings for the purposes of space weather monitoring and prediction. Title: Solar flare prediction: A worthy goal, or a foolish pursuit? (Invited) Authors: McAteer, R.; "All Clear Workshop", "Solarmonitor. Org Team" Bibcode: 2010AGUFMSH54D..02M Altcode: The solar physics community has made a number of progressive breakthroughs in the field of solar flare prediction within the last few years. Although we still do not have a means of predicting the size, timing, and geo-effectiveness of any individual event, we can now predict two ends of the spectrum - the 'all-clear' and the 'big storm'. I will highlight these recent advances, and discuss the major problems associated with this aspect of solar physics. By identifying common features and problems across a number of solar flare prediction techniques, I will propose how this field can advance and show how our lessons learned can be applied to other aspects of solar physics (e.g., nanoflare occurrence, short timescale precursors) Title: Quantifying the Evolving Magnetic Structure of Active Regions Authors: Conlon, Paul A.; McAteer, R. T. James; Gallagher, Peter T.; Fennell, Linda Bibcode: 2010ApJ...722..577C Altcode: The topical and controversial issue of parameterizing the magnetic structure of solar active regions has vital implications in the understanding of how these structures form, evolve, produce solar flares, and decay. This interdisciplinary and ill-constrained problem of quantifying complexity is addressed by using a two-dimensional wavelet transform modulus maxima (WTMM) method to study the multifractal properties of active region photospheric magnetic fields. The WTMM method provides an adaptive space-scale partition of a fractal distribution, from which one can extract the multifractal spectra. The use of a novel segmentation procedure allows us to remove the quiet Sun component and reliably study the evolution of active region multifractal parameters. It is shown that prior to the onset of solar flares, the magnetic field undergoes restructuring as Dirac-like features (with a Hölder exponent, h = -1) coalesce to form step functions (where h = 0). The resulting configuration has a higher concentration of gradients along neutral line features. We propose that when sufficient flux is present in an active region for a period of time, it must be structured with a fractal dimension greater than 1.2, and a Hölder exponent greater than -0.7, in order to produce M- and X-class flares. This result has immediate applications in the study of the underlying physics of active region evolution and space weather forecasting. Title: Evidence for Internal Tether-cutting in a Flare/Coronal Mass Ejection Observed by MESSENGER, RHESSI, and STEREO Authors: Raftery, Claire L.; Gallagher, Peter T.; McAteer, R. T. James; Lin, Chia-Hsien; Delahunt, Gareth Bibcode: 2010ApJ...721.1579R Altcode: The relationship between eruptive flares and coronal mass ejections (CMEs) is a topic of ongoing debate, especially regarding the possibility of a common initiation mechanism. We studied the kinematic and hydrodynamic properties of a well-observed event that occurred on 2007 December 31 using data from MESSENGER, RHESSI, and STEREO in order to gain new physical insight into the evolution of the flare and CME. The initiation mechanism was determined by comparing observations to the internal tether-cutting, breakout, and ideal magnetohydrodynamic (MHD) models. Evidence of pre-eruption reconnection immediately eliminated the ideal MHD model. The timing and location of the soft and hard X-ray sources led to the conclusion that the event was initiated by the internal tether-cutting mechanism. In addition, a thermal source was observed to move in a downward direction during the impulsive phase of the event, followed by upward motion during the decay phase, providing evidence for X- to Y-type magnetic reconnection. Title: Propagation of an Earth-directed coronal mass ejection in three dimensions Authors: Byrne, Jason P.; Maloney, Shane A.; McAteer, R. T. James; Refojo, Jose M.; Gallagher, Peter T. Bibcode: 2010NatCo...1...74B Altcode: 2010NatCo...1E..74B; 2010arXiv1010.0643B Solar coronal mass ejections (CMEs) are the most significant drivers of adverse space weather on Earth, but the physics governing their propagation through the heliosphere is not well understood. Although stereoscopic imaging of CMEs with NASA's Solar Terrestrial Relations Observatory (STEREO) has provided some insight into their three-dimensional (3D) propagation, the mechanisms governing their evolution remain unclear because of difficulties in reconstructing their true 3D structure. In this paper, we use a new elliptical tie-pointing technique to reconstruct a full CME front in 3D, enabling us to quantify its deflected trajectory from high latitudes along the ecliptic, and measure its increasing angular width and propagation from 2 to 46 (~0.2 AU). Beyond 7 , we show that its motion is determined by an aerodynamic drag in the solar wind and, using our reconstruction as input for a 3D magnetohydrodynamic simulation, we determine an accurate arrival time at the Lagrangian L1 point near Earth. Title: Advanced image processing for solar physics Authors: McAteer, R. T. James Bibcode: 2010ada..confE..26M Altcode: No abstract at ADS Title: Characterizing Complexity in Solar Magnetogram Data Using a Wavelet-based Segmentation Method Authors: Kestener, P.; Conlon, P. A.; Khalil, A.; Fennell, L.; McAteer, R. T. J.; Gallagher, P. T.; Arneodo, A. Bibcode: 2010ApJ...717..995K Altcode: The multifractal nature of solar photospheric magnetic structures is studied using the two-dimensional wavelet transform modulus maxima (WTMM) method. This relies on computing partition functions from the wavelet transform skeleton defined by the WTMM method. This skeleton provides an adaptive space-scale partition of the fractal distribution under study, from which one can extract the multifractal singularity spectrum. We describe the implementation of a multiscale image processing segmentation procedure based on the partitioning of the WT skeleton, which allows the disentangling of the information concerning the multifractal properties of active regions from the surrounding quiet-Sun field. The quiet Sun exhibits an average Hölder exponent ~-0.75, with observed multifractal properties due to the supergranular structure. On the other hand, active region multifractal spectra exhibit an average Hölder exponent ~0.38, similar to those found when studying experimental data from turbulent flows. Title: Turbulence, complexity, and solar flares Authors: McAteer, R. T. James; Gallagher, Peter T.; Conlon, Paul A. Bibcode: 2010AdSpR..45.1067M Altcode: 2009arXiv0909.5636M The issue of predicting solar flares is one of the most fundamental in physics, addressing issues of plasma physics, high-energy physics, and modelling of complex systems. It also poses societal consequences, with our ever-increasing need for accurate space weather forecasts. Solar flares arise naturally as a competition between an input (flux emergence and rearrangement) in the photosphere and an output (electrical current build up and resistive dissipation) in the corona. Although initially localised, this redistribution affects neighbouring regions and an avalanche occurs resulting in large scale eruptions of plasma, particles, and magnetic field. As flares are powered from the stressed field rooted in the photosphere, a study of the photospheric magnetic complexity can be used to both predict activity and understand the physics of the magnetic field. The magnetic energy spectrum and multifractal spectrum are highlighted as two possible approaches to this. Title: Computer Vision for SDO: First Results from the SDO Feature Finding Algorithms Authors: Martens, Petrus C.; Attrill, G.; Davey, A.; Engell, A.; Farid, S.; Grigis, P.; Kasper, J.; Korreck, K.; Saar, S.; Su, Y.; Testa, P.; Wills-Davey, M.; Bernasconi, P.; Raouafi, N.; Georgoulis, M.; Deforest, C.; Peterson, J.; Berghoff, T.; Delouille, V.; Hochedez, J.; Mampaey, B.; Verbeek, C.; Cirtain, J.; Green, S.; Timmons, R.; Savcheva, A.; Angryk, R.; Wiegelmann, T.; McAteer, R. Bibcode: 2010AAS...21630804M Altcode: The SDO Feature Finding Team produces robust and very efficient software modules that can keep up with the relentless SDO data stream, and detect, trace, and analyze a large number of phenomena including: flares, sigmoids, filaments, coronal dimmings, polarity inversion lines, sunspots, X-ray bright points, active regions, coronal holes, EIT waves, CME's, coronal oscillations, and jets. In addition we track the emergence and evolution of magnetic elements down to the smallest features that are detectable, and we will also provide at least four full disk nonlinear force-free magnetic field extrapolations per day.

During SDO commissioning we will install in the near-real time data pipeline the modules that provide alerts for flares, coronal dimmings, and emerging flux, as well as those that trace filaments, sigmoids, polarity inversion lines, and active regions. We will demonstrate the performance of these modules and illustrate their use for science investigations. Title: Evidence of Enhanced Particle Acceleration During a Plasmoid-Looptop Collision Observed with RHESSI Authors: Milligan, Ryan; McAteer, R. T. J.; Dennis, B. R.; Young, C. A. Bibcode: 2010AAS...21640426M Altcode: 2010BAAS...41..904M Rare observations are presented of a downward-propagating plasmoid (formed in the wake of an erupting CME) merging with an underlying looptop kernel during an occulted limb event observed with RHESSI. RHESSI lightcurves in the 9-18 keV energy range, as well as that of the 245 MHz channel of the Learmonth Solar Observatory, show enhanced nonthermal emission in the corona at the time of the merging suggesting that additional particle acceleration took place. This was attributed to a secondary episode of magnetic reconnection in the current sheet that formed between the two merging sources. Complimentary observations from the SECCHI suite of instruments onboard STEREO-Behind showed that this process was concurrent with the acceleration phase of the associated CME. From wavelet-enhanced EUVI images evidence of inflowing magnetic field lines prior to the CME eruption is also presented. This combination of observations supports a recent numerical simulation of plasmoid formation, propagation and subsequent particle acceleration due to the tearing mode instability during current sheet formation. Title: Evidence For Internal Tether-cutting in a Flare/CME Event. Authors: Raftery, Claire; Gallagher, P. T.; McAteer, R. T. J.; Lin, C. H.; Delahunt, G. Bibcode: 2010AAS...21631403R Altcode: 2010BAAS...41..894R The relationship between eruptive flares and CMEs is a topic of ongoing debate, especially regarding the possibility of a common initiation mechanism. In order to gain new physical insight into this problem, the kinematic and hydrodynamic properties of a well-observed event were studied using data from MESSENGER, RHESSI and STEREO/Secchi. These data were compared to three theoretical models to determine the event's initiation mechanism. The timing and positioning of EUV and X-ray sources along with evidence for pre-eruption particle acceleration led to the conclusion that the event was initiated by the internal tether-cutting mechanism and was followed by breakout reconnection some 10 minutes after launch. Title: Evidence of a Plasmoid-Looptop Interaction and Magnetic Inflows During a Solar Flare/Coronal Mass Ejection Eruptive Event Authors: Milligan, Ryan O.; McAteer, R. T. James; Dennis, Brian R.; Young, C. Alex Bibcode: 2010ApJ...713.1292M Altcode: 2010arXiv1003.0665M Observational evidence is presented for the merging of a downward-propagating plasmoid with a looptop kernel during an occulted limb event on 2007 January 25. RHESSI light curves in the 9-18 keV energy range, as well as that of the 245 MHz channel of the Learmonth Solar Observatory, show enhanced nonthermal emission in the corona at the time of the merging suggesting that additional particle acceleration took place. This was attributed to a secondary episode of reconnection in the current sheet that formed between the two merging sources. RHESSI images were used to establish a mean downward velocity of the plasmoid of 12 km s-1. Complementary observations from the SECCHI suite of instruments on board STEREO-B showed that this process occurred during the acceleration phase of the associated coronal mass ejection (CME). From wavelet-enhanced EUV Imager, image evidence of inflowing magnetic field lines prior to the CME eruption is also presented. The derived inflow velocity was found to be 1.5 km s-1. This combination of observations supports a recent numerical simulation of plasmoid formation, propagation, and subsequent particle acceleration due to the tearing mode instability during current sheet formation. Title: Automated Detection of Coronal Loops Using a Wavelet Transform Modulus Maxima Method Authors: McAteer, R. T. James; Kestener, Pierre; Arneodo, Alain; Khalil, Andre Bibcode: 2010SoPh..262..387M Altcode: 2010SoPh..tmp...56M; 2010SoPh..tmp...44M; 2010arXiv1002.3107M We propose and test a wavelet transform modulus maxima method for the automated detection and extraction of coronal loops in extreme ultraviolet images of the solar corona. This method decomposes an image into a number of size scales and tracks enhanced power along each ridge corresponding to a coronal loop at each scale. We compare the results across scales and suggest the optimum set of parameters to maximize completeness, while minimizing detection of noise. For a test coronal image, we compare the global statistics (e.g. number of loops at each length) to previous automated coronal-loop detection algorithms. Title: Automated Feature and Event Detection with SDO AIA and HMI Data Authors: Davey, Alisdair; Martens, P. C. H.; Attrill, G. D. R.; Engell, A.; Farid, S.; Grigis, P. C.; Kasper, J.; Korreck, K.; Saar, S. H.; Su, Y.; Testa, P.; Wills-Davey, M.; Savcheva, A.; Bernasconi, P. N.; Raouafi, N. -E.; Delouille, V. A.; Hochedez, J. F. .; Cirtain, J. W.; Deforest, C. E.; Angryk, R. A.; de Moortel, I.; Wiegelmann, T.; Georgouli, M. K.; McAteer, R. T. J.; Hurlburt, N.; Timmons, R. Bibcode: 2010cosp...38.2878D Altcode: 2010cosp.meet.2878D The Solar Dynamics Observatory (SDO) represents a new frontier in quantity and quality of solar data. At about 1.5 TB/day, the data will not be easily digestible by solar physicists using the same methods that have been employed for images from previous missions. In order for solar scientists to use the SDO data effectively they need meta-data that will allow them to identify and retrieve data sets that address their particular science questions. We are building a comprehensive computer vision pipeline for SDO, abstracting complete metadata on many of the features and events detectable on the Sun without human intervention. Our project unites more than a dozen individual, existing codes into a systematic tool that can be used by the entire solar community. The feature finding codes will run as part of the SDO Event Detection System (EDS) at the Joint Science Operations Center (JSOC; joint between Stanford and LMSAL). The metadata produced will be stored in the Heliophysics Event Knowledgebase (HEK), which will be accessible on-line for the rest of the world directly or via the Virtual Solar Observatory (VSO) . Solar scientists will be able to use the HEK to select event and feature data to download for science studies. Title: The propagation of a CME front in 3D Authors: Maloney, Shane; Byrne, Jason; Gallagher, Peter T.; McAteer, R. T. James Bibcode: 2010cosp...38.1867M Altcode: 2010cosp.meet.1867M We present a new three-dimensional (3D) reconstruction of an Earth-directed coronal mass ejec-tion (CME), providing new insight into the processes that control its evolution and propagation. Previously limited fields-of-view and single vantage point observations made it impossible to confidently describe CMEs in 3D. This uncertainty in a CME's position and geometry made comparison to theory difficult and hindered progress. Our 3D reconstruction unambiguously shows three effects at play on the CME: deflection from a high latitude source region, angular width expansion, and interplanetary drag. The CME undergoes a deflection of ∼20° degrees below 10 RSun and slowly tends towards the ecliptic throughout its subsequent propagation. We interpret this deflection as a direct result of the interplay between the CME and the drawn-out dipolar topology of the (solar minimum) coronal magnetic field. The increasing angular width is in excess of that due to simple spherical expansion in the diverging solar wind so an additional source of expansion must be present. The additional source is inferred to be a pressure gradient between the internal pressure (magnetic and gas) of the flux rope relative to the ambient solar wind pressure. Low in the corona there is rapid expansion due to a large pressure difference, but further out the CME approaches equilibrium with the solar wind, and the angular width tends to a constant. The 3D reconstruction allows us to accurately determine the CME kinematics, and we show unambiguously that the interplanetary acceleration is due to aerodynamic drag. Furthermore we derive parameters from our reconstruction that act as inputs to an ENLIL model of the CME's propagation to Earth. The results show the CME undergoes a significant degrease in velocity where it encounters a slow-speed solar wind stream ahead of it (>50 RSun ). This lower velocity agrees with the derived velocity from in-situ data at the L1 point and predicts the correct arrival time, to within minutes. In our ever-increasingly technological society, the accurate prediction of adverse space weather is of paramount impor-tance and to achieve this we must understand the basic processes that govern CMEs. Our 3D reconstruction has allowed us to gain some novel insights into these processes, and emphasises the dynamic interplay between CMEs and solar wind. Title: On the 3-D reconstruction of Coronal Mass Ejections using coronagraph data Authors: Mierla, M.; Inhester, B.; Antunes, A.; Boursier, Y.; Byrne, J. P.; Colaninno, R.; Davila, J.; de Koning, C. A.; Gallagher, P. T.; Gissot, S.; Howard, R. A.; Howard, T. A.; Kramar, M.; Lamy, P.; Liewer, P. C.; Maloney, S.; Marqué, C.; McAteer, R. T. J.; Moran, T.; Rodriguez, L.; Srivastava, N.; St. Cyr, O. C.; Stenborg, G.; Temmer, M.; Thernisien, A.; Vourlidas, A.; West, M. J.; Wood, B. E.; Zhukov, A. N. Bibcode: 2010AnGeo..28..203M Altcode: Coronal Mass ejections (CMEs) are enormous eruptions of magnetized plasma expelled from the Sun into the interplanetary space, over the course of hours to days. They can create major disturbances in the interplanetary medium and trigger severe magnetic storms when they collide with the Earth's magnetosphere. It is important to know their real speed, propagation direction and 3-D configuration in order to accurately predict their arrival time at the Earth. Using data from the SECCHI coronagraphs onboard the STEREO mission, which was launched in October 2006, we can infer the propagation direction and the 3-D structure of such events. In this review, we first describe different techniques that were used to model the 3-D configuration of CMEs in the coronagraph field of view (up to 15 R⊙). Then, we apply these techniques to different CMEs observed by various coronagraphs. A comparison of results obtained from the application of different reconstruction algorithms is presented and discussed. Title: The SolarMonitor Active Region Tracking (SMART) Algorithm: Variation of magnetic feature properties through solar cycle 23 Authors: Higgins, P.; Gallagher, P.; McAteer, R.; Bloomfield, D. Bibcode: 2009AGUFMSH51B1278H Altcode: The SolarMonitor Active Region Tracking (SMART) algorithm is an automated system for detecting, tracking, and cataloging magnetic features throughout their evolution and decay. The SMART method will form the basis of active region extraction and tracking within the Heliophysics Integrated Observatory (HELIO). Magnetic properties such as total flux, flux imbalance, flux emergence rate, Schrijver's R-value, R* (a modified version of R), and Falconer's measurement of non-potentiality are determined for individual features throughout solar cycle 23. The variation of these feature property distributions with progression through the solar cycle is presented. Feature detections using the SMART algorithm for line-of-sight level 1.8 SOHO/MDI magnetogram taken 22 October 2003 at 12:47. Active region candidates are denoted "AR", emerging flux concentrations are denoted "EF", plage regions are denoted "PL" and other flux concentrations are labeled "NF". Title: Reconstructing the 3-D Trajectories of CMEs in the Inner Heliosphere Authors: Maloney, Shane A.; Gallagher, Peter T.; McAteer, R. T. James Bibcode: 2009SoPh..256..149M Altcode: 2009arXiv0905.2153M A method for the full three-dimensional (3-D) reconstruction of the trajectories of coronal mass ejections (CMEs) using Solar TErrestrial RElations Observatory (STEREO) data is presented. Four CMEs that were simultaneously observed by the inner and outer coronagraphs (COR1 and 2) of the Ahead and Behind STEREO satellites were analysed. These observations were used to derive CME trajectories in 3-D out to ∼ 15 R. The reconstructions using COR1/2 data support a radial propagation model. Assuming pseudo-radial propagation at large distances from the Sun (15 - 240 R), the CME positions were extrapolated into the Heliospheric Imager (HI) field-of-view. We estimated the CME velocities in the different fields-of-view. It was found that CMEs slower than the solar wind were accelerated, while CMEs faster than the solar wind were decelerated, with both tending to the solar wind velocity. Title: Magnetic Fields, Flares & Forecasts Authors: Conlon, Paul A.; Kestener, P.; McAteer, R.; Gallagher, P. Bibcode: 2009SPD....40.1602C Altcode: A 2D wavelet transform modulus maxima (WTMM) method is used to characterise the complexity of the distribution of the photospheric magnetic field of active regions. The WTMM method offers increased accuracy and reliability over previous fractal and multifractal methods. The multifractal spectrum of both quiet Sun and active region magnetic features are presented. It is shown that the multifractal nature of the quiet Sun is significantly different from that of an active region. As such, a method is proposed to seperate the information corresponding to the multifractal spectrum of an active region from the surrounding quite Sun texture. The WTMM method and segmentation procedure are shown to detect the internal restructuring of active region magnetic features prior to flaring. We detect two thresholds (Haussdorf dimension > 1.2 and Holder Exponent > -0.7) as possible indicators for conditions favourable to flaring. Title: Observation Of Inflows And Collapsing X-point During CME Initiation Using STEREO And RHESSI Authors: Milligan, Ryan; McAteer, R. T. J.; Dennis, B. Bibcode: 2009SPD....40.2110M Altcode: In the standard flare/CME model, converging magnetic field lines in the corona reconnect to release vast amounts of energy. This liberated energy is used in heating plasma, accelerating particles, and driving coronal mass ejections (CMEs). This work presents tentative observational evidence of converging magnetic field lines before the initiation of a CME using the SECCHI suite of instruments onboard STEREO. During a limb event on 25 January 2007, one 'leg' of the CME is observed to propagate "inwards" at a rate of 1.5 km/s for 4 hours before reconnection occurs. As the CME begins to accelerate, a (thermal) coronal X-ray source is observed by RHESSI in the 6-12 keV energy band. The downward motion of this source is temporally correlated with the acceleration phase of the CME, and is therefore interpreted as the collapsing X-point associated with the reconnection. Title: The kinematics of coronal mass ejections using multiscale methods Authors: Byrne, J. P.; Gallagher, P. T.; McAteer, R. T. J.; Young, C. A. Bibcode: 2009A&A...495..325B Altcode: 2009arXiv0901.3392B Aims: The diffuse morphology and transient nature of coronal mass ejections (CMEs) make them difficult to identify and track using traditional image processing techniques. We apply multiscale methods to enhance the visibility of the faint CME front. This enables an ellipse characterisation to objectively study the changing morphology and kinematics of a sample of events imaged by the Large Angle Spectrometric Coronagraph (LASCO) onboard the Solar and Heliospheric Observatory (SOHO) and the Sun Earth Connection Coronal and Heliospheric Investigation (SECCHI) onboard the Solar Terrestrial Relations Observatory (STEREO). The accuracy of these methods allows us to test the CMEs for non-constant acceleration and expansion.
Methods: We exploit the multiscale nature of CMEs to extract structure with a multiscale decomposition, akin to a Canny edge detector. Spatio-temporal filtering highlights the CME front as it propagates in time. We apply an ellipse parameterisation of the front to extract the kinematics (height, velocity, acceleration) and changing morphology (width, orientation).
Results: The kinematic evolution of the CMEs discussed in this paper have been shown to differ from existing catalogues. These catalogues are based upon running-difference techniques that can lead to over-estimating CME heights. Our resulting kinematic curves are not well-fitted with the constant acceleration model. It is shown that some events have high acceleration below ~5 R. Furthermore, we find that the CME angular widths measured by these catalogues are over-estimated, and indeed for some events our analysis shows non-constant CME expansion across the plane-of-sky. Title: EUV Wave Reflection from a Coronal Hole Authors: Gopalswamy, N.; Yashiro, S.; Temmer, M.; Davila, J.; Thompson, W. T.; Jones, S.; McAteer, R. T. J.; Wuelser, J. -P.; Freeland, S.; Howard, R. A. Bibcode: 2009ApJ...691L.123G Altcode: We report on the detection of EUV wave reflection from a coronal hole, as observed by the Solar Terrestrial Relations Observatory mission. The EUV wave was associated with a coronal mass ejection (CME) erupting near the disk center. It was possible to measure the kinematics of the reflected waves for the first time. The reflected waves were generally slower than the direct wave. One of the important implications of the wave reflection is that the EUV transients are truly a wave phenomenon. The EUV wave reflection has implications for CME propagation, especially during the declining phase of the solar cycle when there are many low-latitude coronal holes. Title: Multiresolution Analysis of Active Region Magnetic Structure and its Correlation with the Mount Wilson Classification and Flaring Activity Authors: Ireland, J.; Young, C. A.; McAteer, R. T. J.; Whelan, C.; Hewett, R. J.; Gallagher, P. T. Bibcode: 2008SoPh..252..121I Altcode: 2008arXiv0805.0101I; 2008SoPh..tmp..134I Two different multiresolution analyses are used to decompose the structure of active-region magnetic flux into concentrations of different size scales. Lines separating these opposite polarity regions of flux at each size scale are found. These lines are used as a mask on a map of the magnetic field gradient to sample the local gradient between opposite polarity regions of given scale sizes. It is shown that the maximum, average, and standard deviation of the magnetic flux gradient for α,β,βγ, and βγδ active-regions increase in the order listed, and that the order is maintained over all length scales. Since magnetic flux gradient is strongly linked to active-region activity, such as flares, this study demonstrates that, on average, the Mt. Wilson classification encodes the notion of activity over all length scales in the active-region, and not just those length scales at which the strongest flux gradients are found. Further, it is also shown that the average gradients in the field, and the average length-scale at which they occur, also increase in the same order. Finally, there are significant differences in the gradient distribution, between flaring and non-flaring active regions, which are maintained over all length scales. It is also shown that the average gradient content of active-regions that have large flares (GOES class "M" and above) is larger than that for active regions containing flares of all flare sizes; this difference is also maintained at all length scales. All of the reported results are independent of the multiresolution transform used. The implications for the Mt. Wilson classification of active-regions in relation to the multiresolution gradient content and flaring activity are discussed. Title: Multiscale Characterization of Eruptive Events Authors: Byrne, J. P.; Young, C. A.; Gallagher, P. T.; McAteer, R. T. J. Bibcode: 2008ASPC..397..162B Altcode: Image processing plays an important role in the analysis of data from space-based instruments. With the large volumes of information currently available from missions such as Hinode and STEREO, our aim is to produce computationally fast methods for extracting features of interest (e.g. loops, filaments, waves and eruptions). Multiscale image processing methods enable us to study these features as a function of scale. Here we describe these methods, and use them to study the multiscale properties of a coronal mass ejection (CME) observed by SOHO/LASCO, and briefly discuss the implications for Hinode. Title: The Kinematics of a Globally Propagating Disturbance in the Solar Corona Authors: Long, David M.; Gallagher, Peter T.; McAteer, R. T. James; Bloomfield, D. Shaun Bibcode: 2008ApJ...680L..81L Altcode: 2008arXiv0805.2023L The kinematics of a globally propagating disturbance (also known as an "EIT wave") is discussed using Extreme UltraViolet Imager (EUVI) data from the Solar Terrestrial Relations Observatory (STEREO). We show for the first time that an impulsively generated propagating disturbance has similar kinematics in all four EUVI passbands (304, 171, 195, and 284 Å). In the 304 Å passband the disturbance shows a velocity peak of 238 ± 20 km s-1 within ~28 minutes of its launch, varying in acceleration from 76 to -102 m s-2. This passband contains a strong contribution from a Si XI line (303.32 Å) with a peak formation temperature of ~1.6 MK. The 304 Å emission may therefore be coronal rather than chromospheric in origin. Comparable velocities and accelerations are found in the coronal 195 Å passband, while lower values are found in the lower cadence 284 Å passband. In the higher cadence 171 Å passband the velocity varies significantly, peaking at 475 ± 47 km s-1 within ~20 minutes of launch, with a variation in acceleration from 816 to -413 m s-2. The high image cadence of the 171 Å passband (2.5 minutes compared to 10 minutes for the similar temperature response 195 Å passband) is found to have a major effect on the measured velocity and acceleration of the pulse, which increase by factors of ~2 and ~10, respectively. This implies that previously measured values (e.g., using EIT) may have been underestimated. We also note that the disturbance shows strong reflection from a coronal hole in both the 171 and 195 Å passbands. The observations are consistent with an impulsively generated fast-mode magnetoacoustic wave. Title: Discovery of Spatial Periodicities in a Coronal Loop Using Automated Edge-Tracking Algorithms Authors: Jess, D. B.; Mathioudakis, M.; Erdélyi, R.; Verth, G.; McAteer, R. T. J.; Keenan, F. P. Bibcode: 2008ApJ...680.1523J Altcode: 2008arXiv0802.1971J A new method for automated coronal loop tracking, in both spatial and temporal domains, is presented. Applying this technique to TRACE data, obtained using the 171 Å filter on 1998 July 14, we detect a coronal loop undergoing a 270 s kink-mode oscillation, as previously found by Aschwanden et al. However, we also detect flare-induced, and previously unnoticed, spatial periodicities on a scale of 3500 km, which occur along the coronal loop edge. Furthermore, we establish a reduction in oscillatory power for these spatial periodicities of 45% over a 222 s interval. We relate the reduction in detected oscillatory power to the physical damping of these loop-top oscillations. Title: Solar feature tracking in both spatial and temporal domains Authors: Jess, D. B.; Mathioudakis, M.; Erdélyi, R.; Verth, G.; McAteer, R. T. J.; Keenan, F. P. Bibcode: 2008IAUS..247..288J Altcode: 2007IAUS..247..288J A new method for automated coronal loop tracking, in both spatial and temporal domains, is presented. The reliability of this technique was tested with TRACE 171 Å observations. The application of this technique to a flare-induced kink-mode oscillation, revealed a 3500 km spatial periodicity which occur along the loop edge. We establish a reduction in oscillatory power, for these spatial periodicities, of 45% over a 322 s interval. We relate the reduction in oscillatory power to the physical damping of these loop-top oscillations. Title: Twisting flux tubes as a cause of micro-flaring activity Authors: Jess, D. B.; McAteer, R. T. J.; Mathioudakis, M.; Keenan, F. P.; Andic, A.; Bloomfield, D. S. Bibcode: 2008IAUS..247..360J Altcode: 2007IAUS..247..360J High-cadence optical observations of an H-α blue-wing bright point near solar AR NOAA 10794 are presented. The data were obtained with the Dunn Solar Telescope at the National Solar Observatory/Sacramento Peak using a newly developed camera system, the rapid dual imager. Wavelet analysis is undertaken to search for intensity-related oscillatory signatures, and periodicities ranging from 15 to 370 s are found with significance levels exceeding 95%. During two separate microflaring events, oscillation sites surrounding the bright point are observed to twist. We relate the twisting of the oscillation sites to the twisting of physical flux tubes, thus giving rise to reconnection phenomena. We derive an average twist velocity of 8.1 km/s and detect a peak in the emitted flux between twist angles of 180° and 230°. Title: Multiscale Analysis of Active Region Evolution Authors: Hewett, R. J.; Gallagher, P. T.; McAteer, R. T. J.; Young, C. A.; Ireland, J.; Conlon, P. A.; Maguire, K. Bibcode: 2008SoPh..248..311H Altcode: Flows in the photosphere of solar active regions are turbulent in nature. Because magnetic fields are frozen into the plasma on the solar surface, magnetograms can be used to investigate the processes responsible for structuring active regions. Here, a continuous wavelet technique is developed, analyzed, and used to investigate the multiscale structure of an evolving active region using magnetograms obtained by the Michelson Doppler Imager (MDI) onboard the Solar and Heliospheric Observatory (SOHO). The multiscale structure was measured using a 2D continuous wavelet technique to extract the energy spectrum of the region over the time scale of 13 days. Preliminary evidence of an inverse cascade in active region NOAA 10488 is presented as well as a potential relationship between energy scaling and flare productivity. Title: Multifractal Properties of Evolving Active Regions Authors: Conlon, P. A.; Gallagher, P. T.; McAteer, R. T. J.; Ireland, J.; Young, C. A.; Kestener, P.; Hewett, R. J.; Maguire, K. Bibcode: 2008SoPh..248..297C Altcode: Magnetohydrodynamic turbulence is thought to be responsible for producing complex, multiscale magnetic field distributions in solar active regions. Here we explore the multiscale properties of a number of evolving active regions using magnetograms from the Michelson Doppler Imager (MDI) on the Solar and Heliospheric Observatory (SOHO). The multifractal spectrum was obtained by using a modified box-counting method to study the relationship between magnetic-field multifractality and region evolution and activity. The initial emergence of each active region was found to be accompanied by characteristic changes in the multifractal spectrum. Specifically, the range of multifractal structures (Ddiv) was found to increase during emergence, as was their significance or support (Cdiv). Following this, a decrease in the range in multifractal structures occurred as the regions evolved to become large-scale, coherent structures. From the small sample considered, evidence was found for a direct relationship between the multifractal properties of the flaring regions and their flaring rate. Title: Twisting flux tubes as a cause of micro-flaring activity Authors: Jess, D. B.; McAteer, R. T. J.; Mathioudakis, M.; Keenan, F. P.; Andic, A.; Bloomfield, D. S. Bibcode: 2007A&A...476..971J Altcode: 2007arXiv0709.2268J High-cadence optical observations of an H-α blue-wing bright point near solar AR NOAA 10794 are presented. The data were obtained with the Dunn Solar Telescope at the National Solar Observatory/Sacramento Peak using a newly developed camera system, the rapid dual imager. Wavelet analysis is undertaken to search for intensity-related oscillatory signatures, and periodicities ranging from 15 to 370 s are found with significance levels exceeding 95%. During two separate microflaring events, oscillation sites surrounding the bright point are observed to twist. We relate the twisting of the oscillation sites to the twisting of physical flux tubes, thus giving rise to reconnection phenomena. We derive an average twist velocity of 8.1 km s-1 and detect a peak in the emitted flux between twist angles of 180° and 230°.

Figure 4 is available as a movie at http://www.aanda.org Title: Two contrasting events from multiple viewpoints Authors: McAteer, R.; Davilla, J.; St. Cyr, C. Bibcode: 2007AGUFMSH41B..05M Altcode: Two contrasting events are described by studying data from both STEREO and earth-Sun line of sight instruments. In each case the image registration and alignment issues are addressed and the specific science benefits of the separation angles of the three viewpoints are highlighted. In the first event (25-Jan-2007), a small flare in a slowly evolving active region ejecting a fast moving CME is studied using EUVI/COR1/COR2 from both STEREO spacecraft, with additional information from EIT/LASCO and RHESSI.The benefits of small spacecraft separation are exploited as pre-CME EUVI (behind) images show significant loop 'opening', with a RHESSI thermal energy source detected prior to the post-flare loops cooling thru the EUVI passbands. The CME passes is studied as it passes thru COR1/COR2 and LASCO, and is followed by a slow moving thermal energy source in its wake. In the second event (1-May-2007), a rapidly rotating (but non-erupting) filament as the source of a slowly rising, non radial, feature is studied using both STEREO spacecraft, SOHO and the Mk-IV coronagraph. The benefits of larger spacecraft separation are exploited to give three plane of sky height time plots to determine the 'actual' velocity profile of the slow moving feature. The differences in EIT and EUVI are used to study the filament rotational motion in detail Title: Multi-scale Tools for Solar Image Processing Authors: Young, C.; Ireland, J.; McAteer, R.; Gallagher, P. T.; Byrne, J. Bibcode: 2007AGUFMSH13A1093Y Altcode: The important information contained in solar image data exists on many different time and spatial scales. This makes multi-scale transforms such as wavelets and curvelets very appropriate tools. These and other multi- scale transforms are used in several different types of image processing including image enhancement, feature detection, deconvolution and noise reduction. We present an overview of multi-scale transforms and show some of their applications to solar image data. Title: The Bursty Nature of Solar Flare X-Ray Emission Authors: McAteer, R. T. James; Young, C. Alex; Ireland, Jack; Gallagher, Peter T. Bibcode: 2007ApJ...662..691M Altcode: The complex and highly varying temporal nature of emission from an X4.8 flare is studied across seven X-ray energy bands. A wavelet transform modulus maxima method is used to obtain the multifractal spectra of the temporal variation of the X-ray emission. As expected from the Neupert effect, the time series of the emission at low energies (3-6, 6-12 keV; thermal) is smooth. The peak Hölder exponent, around 1.2, for this low-energy emission is indicative of a signal with a high degree of memory and suggestive of a smooth chromospheric evaporation process. The more bursty emission at higher energies (100-300, 300-800 keV; nonthermal) is described by a multifractal spectrum that peaks at a smaller Hölder exponent (less than 0.5 for the largest singularities), indicative of a signal with a low degree of memory. This describes an antipersistent walk and indicates an impulsive, incoherent driving source. We suggest that this may arise from bursty reconnection, with each reconnection event producing a different and uncorrelated nonthermal particle source. The existence of a power-law scaling of wavelet coefficients across timescales is in agreement with the creation of a fractal current sheet diffusion region. Title: Wavelet Analysis of Active Region Magnetic Structure Authors: Ireland, Jack; Young, C. A.; Gallagher, P. T.; McAteer, R. T. James; Whelan, C.; Hewett, R. J. Bibcode: 2007AAS...210.9322I Altcode: 2007BAAS...39..214I A wavelet analysis is used to decompose active region magnetic fields into regions of different lengthscales, allowing one to examine the structure of the active region field at different lengthscales. Linesseparating opposite polarity groupings of flux at different lengthscales are found; these lines can be seen as a generalization of the notion of a magnetic neutral line. It is shown that the average magnetic field gradient for alpha, beta, beta-gamma, and beta-gamma-delta active regions increases in the order listed, and that the order is maintained over all length-scales. Further, the standard deviation and maximum of the magnetic field gradient, as well as the length of these generalized neutral lines, all share the same property. Since magnetic field gradient is strongly linked to active region activity, such as flares, this study demonstrates that, on average, the Mt. Wilson classification encodes the notion of activity over all lengthscales in the active region, and not just those lengthscales at which the strongest field gradients are found. This study uses the multiscale analysis toolkit Mkit developed by C. A. Young and presented elsewhere at this meeting. Title: Solar Activity Monitoring Authors: Gallagher, Peter T.; McAteer, R. T. James; Young, C. Alex; Ireland, Jack; Hewett, Russell J.; Conlon, Paul Bibcode: 2007ASSL..344...15G Altcode: No abstract at ADS Title: The Influence of Magnetic Field on Oscillations in the Solar Chromosphere Authors: Bloomfield, D. Shaun; McAteer, R. T. James; Mathioudakis, Mihalis; Keenan, Francis P. Bibcode: 2006ApJ...652..812B Altcode: 2006astro.ph..8314B Two sequences of solar images obtained by the Transition Region and Coronal Explorer in three UV passbands are studied using wavelet and Fourier analysis and compared to the photospheric magnetic flux measured by the Michelson Doppler Interferometer on the Solar Heliospheric Observatory to study wave behavior in differing magnetic environments. Wavelet periods show deviations from the theoretical cutoff value and are interpreted in terms of inclined fields. The variation of wave speeds indicates that a transition from dominant fast-magnetoacoustic waves to slow modes is observed when moving from network into plages and umbrae. This implies preferential transmission of slow modes into the upper atmosphere, where they may lead to heating or be detected in coronal loops and plumes. Title: First results from SECIS observations of the 2001 total Solar eclipse Authors: Katsiyannis, A. C.; Williams, D. R.; Murtagh, F.; McAteer, R. T. J.; Keenan, F. P. Bibcode: 2006AIPC..848...95K Altcode: SECIS observations of the June 2001 total solar eclipse were taken using an Fe XIV 5303 Å filter. Existing software was modified and new code was developed for the reduction and analysis of these data. The observations, data reduction, study of the atmospheric and instrumental effects, together with some preliminary results are discussed. Emphasis is given to the techniques used for the automated alignment of the 8000 images, the software developed for the automated detection of intensity oscillations using wavelet analysis and the application of the Monte Carlo randomisation test as a means of checking the reliability of those detections. In line with findings from the 1999 SECIS total eclipse observations, intensity oscillations with periods in the range of 7-8 s, lying outside coronal loops were also detected. Title: The Complex Sun: Turbulence and Complexity of the Solar atmosphere Authors: McAteer, R. T. James; Gallagher, Peter T.; Ireland, J.; Young, C Alex; Hewett, Russell J.; Conlon, P. Bibcode: 2006ESASP.617E.137M Altcode: 2006soho...17E.137M No abstract at ADS Title: How Complex Are Solar Flare Hrx Lightcurves? A Multiscalar Multifractal Approach. Authors: McAteer, R. T. J.; Young, C.; Ireland, J.; Gallagher, P. T. Bibcode: 2006SPD....37.0824M Altcode: 2006BAAS...38..235M A wavelet transform modulus maxima approach to the calculation of the singularity spectrum is applied to hard X-ray (7 energy bands from 3--800keV) lightcurves from an X4.8 flare on 23 July 2002. The multifractality of each lightcurve is discussed in terms of the Hausdorff dimension, D, of the Holder exponent, h, of each detected singularity. In addition to a general discussion of the technique, we show results showing a general increase in complexity of lightcurves at higher energies Title: Multiscale Structure of Active Region Magnetic Fields Authors: Hewett, Russell J.; Gallagher, P. T.; McAteer, R.; Young, C.; Ireland, J. Bibcode: 2006SPD....37.0301H Altcode: 2006BAAS...38..222H Flows in the photosphere of solar active regions are in a state ofhighly developed turbulence. As magnetic fields are frozen into theplasma in the solar surface, magnetograms can therefore be used toinvestigate the processes responsible for structuring active regions.Here, the multiscale structure of a large sample of active regionmagnetograms from the Michelson Doppler Imager (MDI) onboard theSolar and Heliospheric Observatory (SOHO) are investigated. Initialresults regarding the relationship between multiscale structuring andactive region evolution and flaring activity is discussed. Title: Multifractal Analysis of Solar Magnetograms Authors: Conlon, Paul; McAteer, R. T.; Gallagher, P. T.; Ireland, J.; Young, C. A.; Young, C. A. Bibcode: 2006SPD....37.0303C Altcode: 2006BAAS...38Q.222C Magnetohydrodynamic turbulence is thought to be responsible for structuring sunspot magnetic fields. Here we explore the selfsimilar and multi-scaling properties of this turbulence using multi-fractal methods. The multi-fractal spectrum was obtained from full disk Michelos Doppler Imager magnetograms, to study the relationship between magnetic field multifractality and flaring and non-flaring regions. In particular, box counting and wavelet based techniques where investigated. The discrete box counting method was found to be inadequate for these purposes, primarily due to discretization errors. Wavelet based methods, on the other hand, where found to be more stable for diagnosing turbulence in active region magnetic fields. Title: Wavelet analysis of Active Region structure Authors: Ireland, J.; Young, C. A.; Whelan, C.; Gallagher, P. T.; McAteer, R. T. J.; Hewett, R. J. Bibcode: 2006cosp...36.2595I Altcode: 2006cosp.meet.2595I Active regions are known to consist of complex magnetic fields as evinced by both fractal and multifractal studies In contrast the Mt Wilson classification of active regions is relatively simple yet is useful in predicting the likelihood of flaring events since it considers the overall geometrical structure of the active region In particular neutral lines are especially important in evaluating the likelihood of flare events occurring Wavelet analysis techniques in conjunction with edge detection methods are applied to the problem of diagnosing the gross geometrical structure of active region magnetic field Active region fields are decomposed into their constituent parts using wavelet techniques and edge detection methods are used to characterize the neutral lines present A statistical analysis is presented outlining the utility of this approach in automatically generating a Mt Wilson classification for a given active region Title: Preliminary Results from Secis Observations of the 2001 Total Solar Eclipse Authors: Katsiyannis, A. C.; Williams, D. R.; Murtagh, F.; McAteer, R. T. J.; Keenan, F. P. Bibcode: 2005ESASP.600E..86K Altcode: 2005ESPM...11...86K; 2005dysu.confE..86K No abstract at ADS Title: First Results from Secis Observations of the 2001 Total Solar Eclipse Authors: Katsiyannis, A. C.; Williams, D. R.; Murtagh, F.; McAteer, R. T. J.; Keenan, F. P. Bibcode: 2005ESASP.596E..45K Altcode: 2005ccmf.confE..45K No abstract at ADS Title: Statistics of Active Region Complexity: A Large-Scale Fractal Dimension Survey Authors: McAteer, R. T. James; Gallagher, Peter T.; Ireland, Jack Bibcode: 2005ApJ...631..628M Altcode: A quantification of the magnetic complexity of active regions using a fractal dimension measure is presented. This fully automated approach uses full-disk MDI magnetograms of active regions from a large data set (2742 days of the SOHO mission, 9342 active region images) to compare the calculated fractal dimension of each region to both its Mount Wilson classification and flare rate. Each Mount Wilson class exhibits a similar fractal dimension frequency distribution, possibly suggesting a self-similar nature of all active regions. Solar flare productivity exhibits an increase in both the frequency and GOES X-ray magnitude of flares from regions with higher fractal dimension. Specifically, a lower threshold fractal dimension of 1.2 and 1.25 exists as a necessary, but not sufficient, requirement for an active region to produce M- and X-class flares, respectively, within 24 hr of the observation. Title: Automated Boundary-extraction And Region-growing Techniques Applied To Solar Magnetograms Authors: McAteer, R. T. James; Gallagher, Peter T.; Ireland, Jack; Young, C. Alex Bibcode: 2005SoPh..228...55M Altcode: We present an automated approach to active region extraction from full-disc MDI longitudinal magnetograms. This uses a region-growing technique in conjunction with boundary-extraction to define a number of enclosed contours as belonging to separate regions of magnetic significance on the solar disc. This provides an objective definition of active regions and areas of plage on the Sun. A number of parameters relating to the flare potential of each region are discussed. Title: Wavelet Analysis Methods of Oscillatory Power in Chromospheric Lightcurves Authors: McAteer, R. T.; Bloomfield, D. S. Bibcode: 2005AGUSMSH13C..07M Altcode: The symbiotic relationship between time-series oscillatory power and waves in the chromosphere is studied using several novel wavelet techniques. Theses include automated wave-packet searching routines for large datasets, correlation of wave-packets at multiple heights in the atmosphere, and a full multi-wavelength wavelet-phase analysis (including the cross transform, phase difference and phase coherence). In each study we interpret oscillatory power as a signature of waves in the quiet-Sun chromosphere and relate these wave modes to the underlying photospheric magnetic field. Title: From Raw Data to Flare Predictions: A Fully Automated Technique Authors: McAteer, R. T.; Gallagher, P. T.; Ireland, J.; Young, A. Bibcode: 2005AGUSMSP42A..06M Altcode: With the large volume of solar data which already exists, and expected in the near future with SDO, automated techniques are becoming increasingly vital. We present a fully automated active region extraction routine based on boundary extraction and region growing techniques applied to full disc MDI longitudinal magnetograms. Once extracted, any number of image processing techniques can be applied to the data leading to the possibility of automated classification. We discuss a large scale (9 years of MDI data, ~10,000 active region images) fractal survey of this data. This quantifies the meaning of magnetic complexity, relating lower threshold fractal dimension to the onset of large flares. Title: Representation of Sun Spots with Shapelets Authors: Young, C.; Gallagher, P. T.; Ireland, J.; McAteer, R. Bibcode: 2005AGUSMSP11A..07Y Altcode: Shapelets are complete set of orthonormal functions that can be used to represent most images. These functions are Gauss-Hermite polynomials and are the eigenfunctions of the 2D harmonic oscillator. They were first used in image processing to study the shape of galaxies. Shapelets have properties that allow one to compute quantities such as chirality, shear and asymmetry in images. We use these functions to represent magnetograms of sunspots, allowing us to calculate a large set of descriptive quantities including those previously mentioned. These quantities are then correlated with the current classification schemes used to type sunspots. Title: Magnetohydrodynamic mode coupling in the quiet-Sun network Authors: Bloomfield, D. S.; McAteer, R. T. J.; Mathioudakis, M.; Williams, D. R.; Keenan, F. P. Bibcode: 2005ESASP.560..449B Altcode: 2005csss...13..449B No abstract at ADS Title: Observations of Hα Intensity Oscillations in a Flare Ribbon Authors: McAteer, R. T. James; Gallagher, Peter T.; Brown, Daniel S.; Bloomfield, D. Shaun; Moore, Ruth; Williams, David R.; Mathioudakis, Mihalis; Katsiyannis, A.; Keenan, Francis P. Bibcode: 2005ApJ...620.1101M Altcode: High-cadence Hα blue wing observations of a C9.6 solar flare obtained at Big Bear Solar Observatory using the Rapid Dual Imager are presented. Wavelet and time-distance methods were used to study oscillatory power along the ribbon, finding periods of 40-80 s during the impulsive phase of the flare. A parametric study found statistically significant intensity oscillations with amplitudes of 3% of the peak flare amplitude, periods of 69 s (14.5 mHz) and oscillation decay times of 500 s. These measured properties are consistent with the existence of flare-induced acoustic waves within the overlying loops. Title: Initial Results from Secis Observations of the 2001 Eclipse Authors: Katsiyannis, A. C.; Williams, D. R.; Murtagh, F.; McAteer, R. T. J.; Keenan, F. P. Bibcode: 2004ESASP.575..410K Altcode: 2004soho...15..410K; 2003astro.ph.11534K SECIS observations of the June 2001 total solar eclipse were taken using an Fe xiv 5303 A filter. Existing software was modified and new code was developed for the reduction and analysis of these data. The observations, data reduction, study of the atmospheric and instrumental effects, together with some preliminary results are discussed. Emphasis is given to the techniques used for the automated alignment of the 8000 images, the application of the a Trous algorithm for noise filtering and the software developed for the automated detection of intensity oscillations using wavelet analysis. In line with findings from the 1999 SECIS total eclipse observations, intensity oscillations with periods in the range of 20-30 s, both inside and just outside coronal loops are also presented. Title: Wavelet Phase Coherence Analysis: Application to a Quiet-Sun Magnetic Element Authors: Bloomfield, D. Shaun; McAteer, R. T. James; Lites, Bruce W.; Judge, Philip G.; Mathioudakis, Mihalis; Keenan, Francis P. Bibcode: 2004ApJ...617..623B Altcode: A new application of wavelet analysis is presented that utilizes the inherent phase information residing within the complex Morlet transform. The technique is applied to a weak solar magnetic network region, and the temporal variation of phase difference between TRACE 1700 Å and SOHO/SUMER C II 1037 Å intensities is shown. We present, for the first time in an astrophysical setting, the application of wavelet phase coherence, including a comparison between two methods of testing real wavelet phase coherence against that of noise. The example highlights the advantage of wavelet analysis over more classical techniques, such as Fourier analysis, and the effectiveness of the former to identify wave packets of similar frequencies but with differing phase relations is emphasized. Using cotemporal, ground-based Advanced Stokes Polarimeter measurements, changes in the observed phase differences are shown to result from alterations in the magnetic topology. Title: Waves and wavelets: An automated detection technique for solar oscillations Authors: De Moortel, I.; McAteer, R. T. J. Bibcode: 2004SoPh..223....1D Altcode: 2004SoPh..223....1M This paper investigates the possibility of automating the detection of propagating intensity perturbations in coronal loops using wavelet analysis. Two different sets of TRACE 171 Å images are studied using the automated wavelet routine presented by McAteer et al. (2004). Both localised, short-lived periodicities and sustained, periodic, oscillations are picked up by the routine, with the results dependent to a large extent on the signal-to-noise ratio of the dataset. At present, the automation is only partial; the relevance of the detected periodicity and the identification of the coronal structure supporting it still have to be determined by the user, as does the judging of the accuracy of the results. Care has to be taken when interpreting the results of the wavelet analysis, and a good knowledge of all possible factors that might influence or distort the results is a necessity. Despite these limitations, wavelet analysis can play an important role in automatically identifying a variety of phenomena and in the analysis of the ever-growing (observational or simulated) datasets. Title: Erratum: ``Propagating Waves and Magnetohydrodynamic Mode Coupling in the Quiet-Sun Network'' (ApJ, 604, 936 [2004]) Authors: Bloomfield, D. Shaun; McAteer, R. T. James; Mathioudakis, Mihalis; Williams, David R.; Keenan, Francis P. Bibcode: 2004ApJ...609..465B Altcode: Proof corrections were not carried correctly to the final printed version of this paper, which resulted in an extra set of overbars appearing in both terms of the denominator of equation (3). The correct form of this equation is:C(Δt,ν)=(Σ[Pλ1(t,ν)-Pλ1(t,ν)][Pλ2(t+Δt,ν)-Pλ2(t+Δt,ν)])/(sqrt(Σ[Pλ1(t,ν)-Pλ1(t,ν)]2Σ[Pλ2(t,ν)-Pλ2(t,ν)]2)). (3)As noted in footnote 3, this correlation equation was stated incorrectly in our previous paper (eq. [4] in R. T. J. McAteer et al., ApJ, 604, 936 [2004]). However, the correct form of equation (3), now given here, was used for the analysis in both papers.

The press sincerely regrets this error. Title: Optical Observations of Flare-Induced Oscillations Authors: McATeer, R. T. J.; Gallagher, P. T.; Brown, D. S. Bibcode: 2004AAS...204.9806M Altcode: 2004BAAS...36..985M We present high-cadence H alpha blue wing observations of a C9.6 solar flare. Oscillations (period 40-80s) are shown to be present in the post-flare section of lightcurves from a short-lived flare ribbon. Wavelet analysis is used to show the excellent agreement of oscillatory power at 52.4s with a distance-time plot along one half of the ribbon. A best-fit of an oscillation to the curve shows oscillatory amplitude ∼ 0.03% flare ampltiude, period ∼ 69s and decay time ∼ 500s. These parameters are in good agreement with the formation of a second harmonic acoustic wave. A study of loop lengths along the ribbon also agrees with the presence of a ∼ 50s period

JMA is funded by a NRC Research Associateship. Observations were carried out via a Leverhulme Trust Fellowship. Title: Propagating Waves and Magnetohydrodynamic Mode Coupling in the Quiet-Sun Network Authors: Bloomfield, D. Shaun; McAteer, R. T. James; Mathioudakis, Mihalis; Williams, David R.; Keenan, Francis P. Bibcode: 2004ApJ...604..936B Altcode: High-cadence multiwavelength optical observations were taken with the Dunn Solar Telescope at the National Solar Observatory, Sacramento Peak, accompanied by Advanced Stokes Polarimeter vector magnetograms. A total of 11 network bright points (NBPs) have been studied at different atmospheric heights using images taken in wave bands centered on Mg I b1 - 0.4 Å, Hα, and Ca II K3. Wavelet analysis was used to study wave packets and identify traveling magnetohydrodynamic waves. Wave speeds were estimated through the temporal cross-correlation of signals, in selected frequency bands of wavelet power, in each wavelength. Four mode-coupling cases were identified, one in each of four of the NBPs, and the variation of the associated Fourier power with height was studied. Three of the detected mode-coupling, transverse-mode frequencies were observed in the 1.2-1.6 mHz range (mean NBP apparent flux density magnitudes over 99-111 Mx cm-2), with the final case showing 2.0-2.2 mHz (with 142 Mx cm-2). Following this, longitudinal-mode frequencies were detected in the range 2.6-3.2 mHz for three of our cases, with 3.9-4.1 mHz for the remaining case. After mode coupling, two cases displayed a decrease in longitudinal-mode Fourier power in the higher chromosphere. Title: Ultraviolet Oscillations in the Chromosphere of the Quiet Sun Authors: McAteer, R. T. James; Gallagher, Peter T.; Bloomfield, D. Shaun; Williams, David R.; Mathioudakis, Mihalis; Keenan, Francis P. Bibcode: 2004ApJ...602..436M Altcode: Quiet-Sun oscillations in the four Transition Region and Coronal Explorer (TRACE) ultraviolet passbands centered on 1700, 1600, 1216, and 1550 Å are studied using a wavelet-based technique. Both network and internetwork regions show oscillations with a variety of periods and lifetimes in all passbands. The most frequent network oscillation has a period of 283 s, with a lifetime of 2-3 cycles in all passbands. These oscillations are discussed in terms of upwardly propagating magnetohydrodynamic wave models. The most frequent internetwork oscillation has a period of 252 s, again with a lifetime of 2-3 cycles, in all passbands. The tendency for these oscillations to recur in the same position is discussed in terms of ``persistent flashers.'' The network contains greater oscillatory power than the internetwork at periods longer than 300 s in the low chromosphere. This value is shown to decrease to 250 s in the high chromosphere. The internetwork also displays a larger number of short-lifetime, long-period oscillations than the network, especially in the low chromosphere. Both network and internetwork regions contain a small number of nonrecurring long-lifetime oscillations. Title: Low-frequency oscillations of the solar atmosphere Authors: McAteer, Robert Thomas James Bibcode: 2004PhDT.........6M Altcode: This thesis presents detections of oscillations in multi- wavelength images of the quiet-Sun chromosphere, and interprets these oscillations in terms of various chromospheric wave-heating theories. Oscillations in network bright points (NBPs) are studied in the light of Ca II K3 as a function of radial distance from the centre of each NBP. It is shown that low-frequencies (1 4 mHz) tend to dominate, especially in the central portions, suggesting a magnetic component in any waves present. Correlations between wavelet power density maps of light curves in four optical passbands is used to search for vertically propagating wave packets. In each NBP studied, observational evidence is found for transverse-mode magnetohydrodynamic (MHD) waves (1.3 mHz, 1.9 mHz) propagating upwards from the low- to mid-chromosphere, where they couple to longitudinal-mode MHD waves at twice the originally frequency (2.6 mHz, 3.8 mHz), which then shock in the high-chromosphere. There is also further evidence of other upward- and downward-propagating waves in the 1.3 4.6 mHz range. An automated wavelet analysis routine is developed to provide a comparison, in frequency and duration, between network and internetwork oscillations in ultraviolet images of the quiet Sun. The tendency of the network to contain lower frequencies (peak at 3.5 mHz, with an extended tail down to 1 mHz) is discussed in terms of transverse-mode MHD waves. In contrast, the internetwork contains frequencies around 4 mHz, with oscillations tending to contain a higher degree of spatial memory. These are interpreted as persistent flashers. The network tends to contain more oscillations below 3.3 mHz than the internetwork in the low-chromosphere, with this cross- over frequency increasing to 4 mHz in the upper chromosphere. However, below this cross-over frequency, the internetwork still contains a larger number of oscillations, but with short lifetimes. Both regions also contain a small number of non-recurring long-lived oscillations. Title: Oscillatory Signatures above Quiet Sun Magnetic Elements Authors: Bloomfield, D. S.; McAteer, R. T. J.; Lites, B. W.; Judge, P. G.; Mathioudakis, M.; Keenan, F. P. Bibcode: 2004ESASP.547...51B Altcode: 2004soho...13...51B A new application of wavelet analysis is presented. The data used are part of Joint Observing Proposal 72 between SoHO and TRACE, obtained on 1998 May 16 with accompanying groundbased data taken with the Dunn Solar Telescope at Sacramento Peak, New Mexico. A weak magnetic network region is studied and the temporal variation of phase difference between TRACE 1700 Å and SoHO/SUMER C II intensities is shown. The example clearly highlights the advantages of wavelet analysis over more classical techniques such as Fourier analysis, where the effectiveness of the technique to identify wavepackets with differing phase difference relations is emphasised. Title: An Automated Wavelet Analysis Approach to TRACE Quiet Sun Oscillations Authors: McAteer, R. T. J.; Gallagher, P. T.; Williams, D. R. Williams D. R.; Bloomfield, D. S.; Mathioudakis, M.; Keenan, F. P. Bibcode: 2004ESASP.547..139M Altcode: 2004soho...13..139M An automated wavelet analysis approach to TRACE UV quiet Sun datasets is discussed. Periodicity and lifetime of oscillations present in the network and internetwork are compared and contrasted. This provides a means of extending previous Fourier results into the time-localised domain. The longest lifetime oscillations occur around the acoustic band and the network tends to dominate over the internetwork at periods 4 mins. However, it is shown that the internetwork can dominate over the network at long periods (7 - 20 mins), but only for short lifetimes ( 3 complete oscillations). These results are discussed in terms of chromospheric heating theories. Title: Initial Results from SECIS Observations of the 2001 Eclipse Authors: Katsiyannis, A. C.; McAteer, R. T. J.; Williams, D. R.; Gallagher, P. T.; Keenan, F. P. Bibcode: 2004ESASP.547..459K Altcode: 2004astro.ph.11722K; 2004soho...13..459K SECIS observations of the June 2001 total solar eclipse were taken using an Fe XIV 5303 Å filter. Existing software was modified and new code was developed for the reduction and analysis of these data. The observations, data reduction, study of the atmospheric and instrumental effects, together with some preliminary results are discussed. Emphasis is given to the techniques used for the automated alignment of the 8000 images, the application of the `a Trous algorithm for noise filtering and the software developed for the automated detection of intensity oscillations using wavelet analysis. In line with findings from the 1999 SECIS total eclipse observations, intensity oscillations with periods in the range of 20-30 s, both inside and just outside coronal loops are also presented. Title: Low Frequency Oscillations of the Solar Atmosphere Authors: McAteer, R. T. James Bibcode: 2003PhDT........15M Altcode: This thesis presents detections of intensity oscillations in multi-wavelength image sequences of the quiet-Sun chromosphere, and interprets these oscillations in terms of various chromospheric wave-heating theories. Oscillations in network bright points (NBPs) are studied in the light of Ca II K3 as a function of radial distance from the centre of each NBP. It is shown that low frequencies (1--4mHz) tend to dominate, especially in the central portions, suggesting a magnetic component in any waves present.

Correlations between wavelet power density maps of light curves in four optical passbands is used to search for vertically propagating wave packets. In each NBP studied, observational evidence is found for transverse-mode magnetohydrodynamic (MHD) waves (1.3mHz, 1.9mHz) propagating upwards from the low- to mid- chromosphere, where they couple to longitudinal-mode MHD waves at twice the originally frequency (2.6mHz, 3.8mHz), which then shock in the high-chromosphere. There is also further evidence of other upward- and downward- propagating waves in the 1.3--4.6mHz range.

An automated wavelet analysis routine is developed to compare, in frequency and duration, network and internetwork oscillations, in ultraviolet image sequences of the quiet Sun. The tendency of the network to contain lower frequencies (peak at 3.5mHz, with an extended tail down to 1mHz) is discussed in terms of transverse-mode MHD waves. In contrast, the internetwork contains frequencies around 4mHz, with oscillations tending to contain a higher degree of spatial memory. These are interpreted as persistent flashers. The network tends to contain more oscillations below 3.3mHz than the internetwork in the low-chromosphere, with this cross-over frequency increasing to 4mHz in the upper chromosphere. However, below this cross-over frequency, the internetwork still contains a larger number of oscillations, but with short lifetimes. Both regions also contain a small number of non-recurring long-lived oscillations. Title: Eclipse observations of high-frequency oscillations in active region coronal loops Authors: Katsiyannis, A. C.; Williams, D. R.; McAteer, R. T. J.; Gallagher, P. T.; Keenan, F. P.; Murtagh, F. Bibcode: 2003A&A...406..709K Altcode: 2003astro.ph..5225K One of the mechanisms proposed for heating the corona above solar active regions is the damping of magnetohydrodynamic (MHD) waves. Continuing on previous work, we provide observational evidence for the existence of high-frequency MHD waves in coronal loops observed during the August 1999 total solar eclipse. A wavelet analysis is used to identify twenty 4x4 arcsec2 areas showing intensity oscillations. All detections lie in the frequency range 0.15-0.25 Hz (7-4 s), last for at least 3 periods at a confidence level of more than 99% and arise just outside known coronal loops. This leads us to suggest that they occur in low emission-measure or different temperature loops associated with the active region. Title: White-light oscillations during a flare on II Peg. Authors: Mathioudakis, M.; Seiradakis, J. H.; Williams, D. R.; Avgoloupis, S.; Bloomfield, D. S.; McAteer, R. T. J. Bibcode: 2003A&A...403.1101M Altcode: We analyse the intensity oscillations observed in the gradual phase of a white-light flare on the RS CVn binary II Peg. Fast Fourier Transform power spectra and Wavelet analysis reveal a period of 220 s. The reliability of the oscillation is tested using several criteria. Oscillating coronal loop models are used to derive physical parameters such as temperature, electron density and magnetic field strength associated with the coronal loop. The derived parameters are consistent with the near-simultaneous X-ray observations of the flare. There is no evidence for oscillations in the quiescent state of the binary. Title: Observational Evidence for Mode Coupling in the Chromospheric Network Authors: McAteer, R. T. James; Gallagher, Peter T.; Williams, David R.; Mathioudakis, Mihalis; Bloomfield, D. Shaun; Phillips, Kenneth J. H.; Keenan, Francis P. Bibcode: 2003ApJ...587..806M Altcode: Oscillations in network bright points (NBPs) are studied at a variety of chromospheric heights. In particular, the three-dimensional variation of NBP oscillations is studied using image segmentation and cross-correlation analysis between images taken in light of Ca II K3, Hα core, Mg I b2, and Mg I b1-0.4 Å. Wavelet analysis is used to isolate wave packets in time and to search for height-dependent time delays that result from upward- or downward-directed traveling waves. In each NBP studied, we find evidence for kink-mode waves (1.3, 1.9 mHz), traveling up through the chromosphere and coupling with sausage-mode waves (2.6, 3.8 mHz). This provides a means for depositing energy in the upper chromosphere. We also find evidence for other upward- and downward-propagating waves in the 1.3-4.6 mHz range. Some oscillations do not correspond to traveling waves, and we attribute these to waves generated in neighboring regions. Title: An observational study of a magneto-acoustic wave in the solar corona Authors: Williams, D. R.; Mathioudakis, M.; Gallagher, P. T.; Phillips, K. J. H.; McAteer, R. T. J.; Keenan, F. P.; Rudawy, P.; Katsiyannis, A. C. Bibcode: 2002MNRAS.336..747W Altcode: The Solar Eclipse Corona Imaging System (SECIS) observed a strong 6-s oscillation in an active region coronal loop, during the 1999 August 11 total solar eclipse. In the present paper we show that this oscillation is associated with a fast-mode magneto-acoustic wave that travels through the loop apex with a velocity of 2100 km s-1. We use near-simultaneous SOHO observations to calculate the parameters of the loop and its surroundings such as density, temperature and their spatial variation. We find that the temporal evolution of the intensity is in agreement with the model of an impulsively generated, fast-mode wave. Title: Detections of high-frequency oscillations in solar active region coronal loops Authors: Katsiyannis, Athanassios C.; Williams, David R.; McAteer, R. T. James; Gallagher, Peter T.; Mathioudakis, Mihalis; Keenan, Francis P. Bibcode: 2002ESASP.505..441K Altcode: 2002IAUCo.188..441K; 2002solm.conf..441K One of the mechanisms proposed as a possible solution to the Sun's coronal heating problem is the damping of energy carried by magnetohydrodynamic (MHD) waves that are expected to be present in active regions. Continuing previous work on total solar eclipse data, we provide further obervational evidence for the existence of high-frequency MHD waves in coronal loops. Wavelet analysis is used to identify 21 areas of 4×4 arcsec2 with periodic intensity oscillations. The frequency range of these detections was 0.2-0.3 Hz and all last for at least 3 periods at a confidence level of more than 99%. All of the above detections are made just outside known coronal loops, leading us to suggest a possible, unconventional mechanism. Title: Detection of propagating waves throughout the chromosphere in network bright points Authors: McAteer, R. T. James; Gallagher, Peter T.; Williams, David R.; Mathioudakis, Mihalis; Phillips, Kenneth J. H.; Keenan, Francis P. Bibcode: 2002ESASP.505..305M Altcode: 2002IAUCo.188..305M; 2002solm.conf..305M We analysed oscillations in individual Network Bright Points (NBPs) in Ca II K3, Hα core, Mg I b2, and Mg I b1-0.4 Å giving us a range of heights from the upper to the lower chromosphere. Lightcurves, and hence power spectra, were created by isolating distinct regions of the NBP via a simple intensity thresholding technique. Using this technique, it was possible to identify peaks in the power spectra with particular spatial positions within the NBPs. This was extended into the time domain by means of wavelet analysis. We track the temporal evolution of power in particular frequency bands by creating power curves. These are then cross-correlated across all observed wavelengths to search for propagating waves. In particular, long-period waves with periods of 4-15 minutes (1-4 mHz) were found in the central portion of each NBP, indicating that these waves are certainly not acoustic, but possibly due to magneto-acoustic or magneto-gravity wave modes. We note the possible existence of fast-mode MHD waves in the lower chromosphere, coupling and transferring power top higher-frequency slow-mode MHD waves in the upper chromosphere. Title: Observations of a high-frequency, fast-mode wave in a coronal loop Authors: Williams, David R.; Mathioudakis, Mihalis; Gallagher, Peter T.; Phillips, Kenneth J. H.; McAteer, R. T. James; Keenan, Francis P.; Katsiyannis, Athanassios C. Bibcode: 2002ESASP.505..615W Altcode: 2002IAUCo.188..615W; 2002solm.conf..615W The high-cadence Solar Eclipse Corona Imaging System (SECIS) observed a strong 6-second oscillation in an active region coronal loop, during the 1999 August 11 total solar eclipse. In the present paper we show that this oscillation is associated with a fast-mode wave that travels through the loop apex with a velocity of ~2000 km s-1. We use near-simultaneous SoHO/CDS obervations to calculate the parameters of the loop and its surroundings such as density, temperature and their spatial variation. We also calculate radiative losses from the loop in the temperature range 105.8 - 106.4K, and compare these losses with the wave energy density. Although the wave travels a distance greater than λ/4π and therefore meets a necessary criterion for slow dissipation, the dissipation length is well in excess of the loop length. The temporal evolution of the intensity is found to be in agreement with the model of an impulsively generated, fast-mode wave. Title: Long-Period Chromospheric Oscillations in Network Bright Points Authors: McAteer, R. T. James; Gallagher, Peter T.; Williams, David R.; Mathioudakis, Mihalis; Phillips, Kenneth J. H.; Keenan, Francis P. Bibcode: 2002ApJ...567L.165M Altcode: The spatial variation of chromospheric oscillations in network bright points (NBPs) is studied using high-resolution observations in Ca II K3. Light curves and hence power spectra were created by isolating distinct regions of the NBP via a simple intensity thresholding technique. Using this technique, it was possible to identify peaks in the power spectra with particular spatial positions within the NBPs. In particular, long-period waves with periods of 4-15 minutes (1-4 mHz) were found in the central portions of each NBP, indicating that these waves are certainly not acoustic but possibly due to magnetoacoustic or magnetogravity wave modes. We also show that spatially averaged or low spatial resolution power spectra can lead to an inability to detect such long-period waves.