Author name code: malanushenko-anna ADS astronomy entries on 2022-09-14 author:"Malanushenko, Anna V." ------------------------------------------------------------------------ Title: Derivation of Boundary Conditions for Data-Driven Simulations of Active Regions and their Emission Authors: Tremblay, Benoit; Malanushenko, Anna; Rempel, Matthias; Kazachenko, Maria Bibcode: 2022cosp...44.2472T Altcode: Coronal heating remains a major area of research in solar physics. In particular, the spatial dimensions and the structuring of heating processes have yet to be fully understood. Whereas observations suggest that plasma is heated in bundles of thin flux tubes, it's been theorized from simulations that emission in active regions can be structured in larger flux tubes with irregular boundaries. In the latter case, the emission can appear like the emission from loop bundles, with variations of the column depth at their boundaries causing an impression of individual loops. These scenarios have distinct implications for coronal heating and the study of coronal loops and thus need to be confirmed observationally. Our objective is to develop insight into the spatial properties of solar coronal heating using a statistical analysis of the emission from observed and simulated active regions. To this end, we perform data-driven MHD simulations of active regions. The MURaM simulation is being modified to work with photospheric inputs as boundary conditions, including observed vector magnetograms, and electric field maps and flow maps inferred from observations. We focus on electric field maps derived using the PDFI\_SS inversion technique and flow maps derived through supervised deep learning. More specifically, we train a convolutional neural network to emulate the MURaM simulation and infer MURaM-like flows from observational data, including large-scale flows in the granulation surrounding active regions. We present derivations of boundary conditions (i.e., electric field maps, flows maps) from SDO/HMI observations of selected active regions, and discuss the limitations and challenges associated with the methods. We detail ongoing efforts in driving the MURaM simulation from derived boundary conditions. Finally, we illustrate how these data-driven simulations will be used to study the structuring of the emission of active regions statistically and identify which scenario of coronal heating best matches observations. Title: A Statistical Approach to Study Fine Structure of EUV Emission in Active Regions Authors: Malanushenko, Anna; Rempel, Matthias; Tremblay, Benoit; Kazachenko, Maria Bibcode: 2022cosp...44.2526M Altcode: Heating of the solar corona is one of the major problems in solar physics, and spatial dimension and structuring of the processes involved in heating are yet to be understood. Observations of the numerous thin coronal loops above active regions (ARs) suggest that coronal heating itself is highly variable on small scales, heating plasma in collections of thin flux tubes. It has recently been theorized, based on simulations, that emitting plasma in ARs can also be structured in larger flux tubes with irregular boundaries. The emission of these large flux tubes can appear like emission of loop bundles, with variations of the column depth at their boundaries causing an impression of individual loops. This "coronal veil" theory was argued to be a more general scenario, which better explains AR emission properties than previous models. If confirmed observationally, it will have a large impact on coronal heating studies, suggesting that existing measurements of temperature and density in coronal loops may need to be reevaluated. The observational validation of this hypothesis is as important as it is difficult. For a given coronal loop, it is difficult to tell whether it is a compact feature or a projection artifact. In this talk, we propose a new statistical approach to address this problem. Instead of trying to analyze each loop individually, we focus on scaling relationship between a number of loops in a given AR and the AR's total brightness in a given wavelength. We argue that these two quantities are related by a power law. We demonstrate in theoretical calculations how the power law coefficients will differ depending on whether the emission is structured into (a) compact features, (b) large features with irregular boundaries, or (c) extended and thin veil-like features. We demonstrate that these power laws exist in observations and discuss numerical experiments which may help us to determine which of these scenarios, if any, best describes observations. We further describe the observational statistics that can, in conjunction with numerical experiments, help us understand which of these scenarios take place in the Sun. We also present the first results from our project to collect these data. Title: Extracting characteristics of interplanetary CMEs from database of synthetic white-light images based on ensemble MHD simulations Authors: Provornikova, Elena; Gibson, Sarah; Wiltberger, Michael; Dalmasse, Kévin; Merkin, Viacheslav; Malanushenko, Anna; Vourlidas, Angelos; Arge, Charles Bibcode: 2022cosp...44.2433P Altcode: In this work, we investigate to what extent properties of CMEs determined from synthetic white light images represent properties of simulated interplanetary CMEs. The propagation of an interplanetary CME with an internal flux rope is modeled with the GAMERA global model of the inner heliosphere (0.1- 1 AU) coupled with the Gibson-Low (G&L) model of a self-similarly expanding CME with an internal magnetic field. The solar wind background in the inner heliosphere is driven by the Wang-Sheeley-Arge (WSA)-ADAPT corona solution. An ensemble of CME simulations is created by setting different input parameters of a CME flux rope in the G&L model (e.g., magnetic field topology and magnetic field strength, angular width, speed, orientation, latitude, and longitude). A set of values for each of the defining G&L parameters are taken from statistical distributions obtained from an analysis of white light CME imagery near the Sun. To set the CME magnetic structure we choose four topologies allowed by the G&L model: spheromak, tethered spheromak, flux rope, and magnetic arcade. We run an ensemble of a few hundred MHD simulations of interplanetary CMEs with internal flux rope. The ensemble is used to produce a database of synthetic CME images in white-light total brightness. We use the CACTUS package to autonomously detect CMEs in synthetic white light images and determine CME angular width and variations of CME velocity, mass, and trajectory during the interplanetary CME propagation. We then compare results from CACTUS with the ground truth data extracted directly from MHD simulation output. We analyze cases showing a disagreement between the true and inferred properties in more detail. Title: Exploring Structures and Flows with NASA's under-construction PUNCH mission Authors: DeForest, Craig; Gibson, Sarah; Thompson, Barbara; Malanushenko, Anna; Desai, Mihir; Elliott, Heather; Viall, Nicholeen; Cranmer, Steven; de Koning, Curt Bibcode: 2022cosp...44.1077D Altcode: The Polarimeter to UNify the Corona and Heliosphere is a NASA Small Explorer to image the corona and heliosphere as parts of a single system. PUNCH comprises four ~50kg smallsats, each carrying one imaging instrument, that work together to form a single "virtual coronagraph" with a 90° field of view, centered on the Sun. Scheduled for joint launch with NASA's SPHEREx mission, PUNCH starts its two-year prime science phase in 2025. PUNCH will generate full polarized image sequences of Thomson-scattered light from free electrons in the corona and young solar wind, once every four minutes continuously. This enables tracking the young solar wind and turbulent structures within it as they disconnect from the Sun itself, as well as large transients such as CMEs, CIRs, and other shocks within the young solar wind. A student-contributed X-ray spectrometer (STEAM) will address questions of coronal heating and flare physics. We present motivating science, expected advances, mission status, and how to get involved with PUNCH science now. Title: Expected results for the cradle of the Solar Wind with the Polarimeter to UNify the Corona and Heliosphere (PUNCH) Authors: DeForest, Craig; Gibson, Sarah; De Koning, Curt A.; Thompson, Barbara; Malanushenko, Anna; Desai, Mihir; Elliott, Heather; Viall, Nicholeen; Cranmer, Steven Bibcode: 2022cosp...44.1324D Altcode: The Polarimeter to UNify the Corona and Heliosphere is a NASA Small Explorer to image the corona and heliosphere as parts of a single system. Imaging the corona and heliosphere together from a constellation of four synchronized smallsats, PUNCH will — starting in 2025 — provide a unique window on global structure and cross-scale processes in the outer corona and young solar wind. PUNCH science is informed by, and complements, the results of PSP and Solar Orbiter; and will synergize with PROBA3/ASPIICS. We present early prototype results from STEREO/SECCHI and current preparation work to enable PUNCH science when data arrive, discuss anticipated results from the deeper-field, higher time resolution imaging that PUNCH will provide, and describe how to get involved with PUNCH science now. Title: The Coronal Veil Authors: Malanushenko, A.; Cheung, M. C. M.; DeForest, C. E.; Klimchuk, J. A.; Rempel, M. Bibcode: 2022ApJ...927....1M Altcode: 2021arXiv210614877M Coronal loops, seen in solar coronal images, are believed to represent emission from magnetic flux tubes with compact cross sections. We examine the 3D structure of plasma above an active region in a radiative magnetohydrodynamic simulation to locate volume counterparts for coronal loops. In many cases, a loop cannot be linked to an individual thin strand in the volume. While many thin loops are present in the synthetic images, the bright structures in the volume are fewer and of complex shape. We demonstrate that this complexity can form impressions of thin bright loops, even in the absence of thin bright plasma strands. We demonstrate the difficulty of discerning from observations whether a particular loop corresponds to a strand in the volume, or a projection artifact. We demonstrate how apparently isolated loops could deceive observers, even when observations from multiple viewing angles are available. While we base our analysis on a simulation, the main findings are independent from a particular simulation setup and illustrate the intrinsic complexity involved in interpreting observations resulting from line-of-sight integration in an optically thin plasma. We propose alternative interpretation for strands seen in Extreme Ultraviolet images of the corona. The "coronal veil" hypothesis is mathematically more generic, and naturally explains properties of loops that are difficult to address otherwise-such as their constant cross section and anomalously high density scale height. We challenge the paradigm of coronal loops as thin magnetic flux tubes, offering new understanding of solar corona, and by extension, of other magnetically confined bright hot plasmas. Title: Establishing flux rope chirality using white light polarization data from the PUNCH mission Authors: Gibson, Sarah; Morgan, Huw; Provornikova, Elena; Malanushenko, Anna; DeForest, Craig; de Koning, Curt; Fan, Yuhong; Merkin, Viacheslav; Webb, David Bibcode: 2021AGUFMSH32A..03G Altcode: Interplanetary Coronal Mass Ejections (ICMEs) are generally expected to incorporate coherently-twisted magnetic fields, i.e., magnetic flux ropes. We expect and have observed to some extent evolution and interactions between flux ropes and the background corona and solar wind, including rotation, deflection, and potentially continued topological changes. The upcoming PUNCH mission will provide a full field of view from pole to pole and fill existing gaps between coronagraphs and heliospheric imagers, and will obtain polarized brightness measurements which may be used along with brightness measurements as a powerful tool for imaging and localizing CME substructure evolution in transit. Further analysis of these substructures may then lead to information about the chirality, or handedness of magnetic twist of the flux rope. In order to demonstrate these capabilities, we present synthetic polarization from forward modeled simulations of flux rope CMEs. We compare the 3D position of substructure that can be extracted from these data to the ground truth simulation knowledge of the position of mass along the line of sight. We further consider the implications for chirality and the robustness of the method to topological variation of the flux rope at the heart of the ICME. Title: Analyzing the Structure of Coronal Loops in MURaM Radiation MHD Simulations Authors: David, Mia; Rempel, Matthias; Malanushenko, Anna Bibcode: 2021AGUFMSH45B2377D Altcode: Coronal loops are emission features that trace out parts of the solar magnetic field in the corona, and as such they provide important information about the magnetic and plasma structure of the solar corona. Their thermal substructure is still an open question: their thickness is at the limit of resolution of the instruments observing them, and higher resolution instruments tend to find finer strands. This raises the question whether the finest strands are resolved with the currently available highest resolution instruments. In this project, we address this from a modeling perspective and look to answer the following questions. Does the number of strands identified in synthetic observations depend on the resolution of the numerical simulation? How many strands remain hidden in current observations that may otherwise be evident in future higher resolution observations? We look at simulations done with MURaM code of a bipolar active region that are available at three different numerical resolutions. We emulate observables at various resolutions, including one which exceeds that of current instruments. We synthesize data in resolution of Atmospheric Imaging Assembly onboard Solar Dynamics Observatory (SDO/AIA) and High-Resolution Coronal Imager (HiC). We find that the number of strands found in synthetic AIA does not depend on the resolution of the simulation, and that it is a small fraction of the strands found in the native resolution of the simulation. The number of strands seen in synthetic HiC data is a factor of 2-4 higher than that in synthetic AIA, and increases moderately with the resolution of the simulation. We compare the results with observations by studying an active region observed by AIA. We study the dependence of the number of loops counted on the viewing angle in both synthetic and observable data. We also report statistical properties of these strands. Title: A Statistical Approach to Study Spatial Characteristics of EUV Emission in Active Regions Authors: Malanushenko, Anna; Egeland, Ricky; Kazachenko, Maria; Rempel, Matthias; Tremblay, Benoit Bibcode: 2021AGUFMSH45B2360M Altcode: Heating of the solar corona is one of the major problems in solar physics, and spatial dimension and structuring of the processes involved in heating are yet to be understood. Observations of the numerous thin coronal loops above active regions (ARs) suggest that coronal heating itself is highly variable on small scales, heating plasma in collections of thin flux tubes. It has recently been theorized, based on simulations, that emitting plasma in ARs can also be structured in larger flux tubes with irregular boundaries. The emission of these large flux tubes can appear like emission of loop bundles, with variations of the column depth at their boundaries causing an impression of individual loops. This "coronal veil" theory was argued to be a more general scenario, which better explains AR emission properties than previous models. If confirmed observationally, it will have a large impact on coronal heating studies, suggesting that existing measurements of temperature and density in coronal loops may need to be reevaluated. The observational validation of this hypothesis is as important as it is difficult. For a given coronal loop, it is difficult to tell whether it is a compact feature or a projection artifact. In this talk, we propose a new statistical approach to address this problem. Instead of trying to analyze each loop individually, we focus on scaling relationship between a number of loops in a given AR and the AR's total brightness in a given wavelength. We argue that these two quantities are related by a power law. We demonstrate in theoretical calculations how the power law coefficients will differ depending on whether the emission is structured into (a) compact features, (b) large features with irregular boundaries, or (c) extended and thin veil-like features. We demonstrate that these power laws exist in observations and discuss numerical experiments which may help us to determine which of these scenarios, if any, best describes observations. Title: Visualizing the Solar Corona in Virtual Reality Authors: Wolff, Milana; Dima, Gabriel; Rempel, Matthias; Lacatus, Daniela; Paraschiv, Alin; Lecinski, Alice; Malanushenko, Anna Bibcode: 2021AGUFMSH45B2365W Altcode: This work presents novel visualizations of the optically thin solar corona in a virtual reality environment created using the Unity development platform. Unity enables fast rendering and interaction with three dimensional datasets in an immersive setting. We depict data derived from coronal simulations generated by radiative magnetohydrodynamic MURaM. These visualizations represent synthetic emissivity values computed for a variety of coronal emission lines using high-resolution, time-dependent thermodynamic and magnetic datasets. Users can enter the virtual environment, accessible on desktop and mobile devices or with a virtual reality head-mounted display (such as Oculus or Vive headsets) and observe and interact with both static and dynamic structures in the solar corona from arbitrary vantage points. These types of direct interaction techniques with simulated large-scale structures enhance intuitive understanding of solar dynamics. We welcome ideas from the community on how to further leverage this technology. Title: Large ensemble simulations of CMEs in the inner heliosphere: toward constraining distributions of CME parameters near the Sun Authors: Provornikova, Elena; Merkin, Viacheslav; Malanushenko, Anna; Gibson, Sarah; Vourlidas, Angelos; Arge, Charles; Dalmasse, Kevin Bibcode: 2021AGUFMSH32A..01P Altcode: In this work, we take a comprehensive approach which combines physics-based simulations, observations and statistical methods toward understanding the evolution of coronal mass ejections in the inner heliosphere and linking characteristics of CMEs near the Sun and their plasma and magnetic field properties as they would be observed at 1 AU. We simulate the propagation of ICMEs using a global model of the inner heliosphere driven at the coronal boundary by the Wang-Sheeley-Arge (WSA)-ADAPT model. ICMEs are initiated at 21.5 solar radii using an MHD analytical Gibson-Low (G&L) model of a self-similarly expanding magnetic bubble with defining parameters (e.g., latitude and longitude, magnetic field topology and strength, angular width, speed, orientation). The ICME propagation is simulated using the inner heliosphere version of the Grid Agnostic MHD for Extended Research Applications (GAMERA) MHD model, which is a reinvention of the high-heritage Lyon-Fedder-Mobarry (LFM) code. A set of values for each of the defining G&L parameters was constrained by the statistical representation of CME images near the Sun. Intending to span the solar cycle, we model ICME propagation in different solar wind backgrounds corresponding to rising, declining, and minimum solar cycle phases. A grid of CME parameters and three solar wind backgrounds constitute a parameter space for 50,000 ICME simulations. We describe types and a structure of the output data from simulations and an algorithm of automatic performance of many thousands of runs. We discuss methods to incorporate CME data from both solar observations and in-situ at 1 AU in a statistical study to construct posterior predictive distributions of CME model input parameters. Title: Multi-spacecraft Observations Of Coronal Loops To Verify A Force-free Field Reconstruction And Infer Loop Cross Sections Authors: McCarthy, M.; Longcope, D.; Malanushenko, A. Bibcode: 2021AAS...23820501M Altcode: Active region EUV loops are believed to trace a subset of magnetic field lines through the corona. Malanushenko et al. (2009) proposed a method, using loop images and line-of-sight photospheric magnetograms, to infer the three-dimensional shape and field strength along each loop. McCarthy et al. (2019) used this novel method to compute the total magnetic flux interconnecting a pair of active regions observed by SDO/AIA. They adopted the common assumption that each loop had a circular cross section. The accuracy of inferred shape and circularity of cross sections can both be tested using observations of the same loops from additional vantage points as provided by STEREO/EUVI. Here, we use multiple viewing angles to confirm the three-dimensional structure of loops. Of 151 viable cases, 105 (69.5%) matched some form of visible coronal structure when viewed approximately in quadrature. A loop with a circular cross-section should appear of a similar width in different perspectives. In contradiction to this, we find a puzzling lack of correlation between loop diameters seen from different perspectives, even an anti-correlation in some cases. Features identified as monolithic loops in AIA may, in fact, be more complex density enhancements. The 30.5% of reconstructions from AIA which did not match any feature in EUVI might be such enhancements. Others may be genuine loop structures, but with elliptical cross sections. We observe an anti-correlation between diameter and brightness, lending support to the latter hypothesis. Four loops are consistent with non-circular cross sections, where we find anti-correlation in both comparisons. Title: Identifying Non-potential Energy Hot Spots In A Global Coronal Simulation Authors: Corchado Albelo, M. F.; Gibson, S. E.; Linker, J.; Mackay, D. H.; Dalmasse, K.; Malanushenko, A. Bibcode: 2021AAS...23832803C Altcode: Observing the global coronal magnetic field remains a difficult task; limiting our understanding of the evolution of global phenomena in these external layers of the solar atmosphere. Therefore, we rely on models to get the solar exterior global field. While models can extrapolate the magnetic field from surface flux and vector magnetogram observations, e.g. by assuming a current-free corona, other techniques are used to simulate the current-carrying field via magnetohydrodynamic (MHD) evolution or surface flux transport of large scale field, and inserting current-carrying small scale field structures like twisted flux ropes into the corona. These current-carrying fields are of interest for studying solar energetic eruptions like coronal mass ejections and flares because they provide the energy reservoir needed to drive these events. Previous studies suggest that ground-based infrared polarimetric measurements of Fe XIII (1074.7 nm) line correlate with the energy of the current-carrying field. In this study we generated synthetic polarimetric observations from a fully-resolved magnetohydrodynamics model of the August 21, 2017 eclipse. The synthetic observations were used as input to a diagnostic we developed to identify regions where the modeling team inserted twisted flux ropes. The diagnostic evaluated linearly and circularly polarized synthetic observations of the corona as a means to identify the current-carrying magnetic energy density. We found that the diagnostic does identify the distribution of flux ropes in the corona. Thus, our findings motivate the implementation of polarimetric measurements to identify "hot spots" in which we can insert flux ropes and a degree of the twist/shear in the current-carrying field. Title: Multispacecraft Observations of Coronal Loops to Verify a Force-free Field Reconstruction and Infer Loop Cross Sections Authors: McCarthy, Marika I.; Longcope, Dana W.; Malanushenko, Anna Bibcode: 2021ApJ...913...56M Altcode: 2021arXiv210402722M Active region EUV loops are believed to trace a subset of magnetic field lines through the corona. Malanushenko et al. proposed a method, using loop images and line-of-sight photospheric magnetograms, to infer the 3D shape and field strength along each loop. McCarthy et al. used this novel method to compute the total magnetic flux interconnecting a pair of active regions observed by SDO/AIA. They adopted the common assumption that each loop had a circular cross section. The accuracy of inferred shape and circularity of cross sections can both be tested using observations of the same loops from additional vantage points as provided by STEREO/EUVI. Here we use multiple viewing angles to confirm the 3D structure of loops. Of 151 viable cases, 105 (69.5%) matched some form of visible coronal structure when viewed approximately in quadrature. A loop with a circular cross section should appear of a similar width in different perspectives. In contradiction to this, we find a puzzling lack of correlation between loop diameters seen from different perspectives, even an anticorrelation in some cases. Features identified as monolithic loops in AIA may, in fact, be more complex density enhancements. The 30.5% of reconstructions from AIA that did not match any feature in EUVI might be such enhancements. Others may be genuine loop structures, but with elliptical cross sections. We observe an anticorrelation between diameter and brightness, lending support to the latter hypothesis. Of 13 loops suitable for width analysis, 4 are consistent with noncircular cross sections, where we find anticorrelation in both comparisons. Title: Gibson & Low Flux Rope Model: More Than a Spheromak! Authors: Malanushenko, Anna; Gibson, Sarah; Provornikova, Elena; Dalmasse, Kévin; Merkin, Viacheslav; Vourlidas, Angelos; Nychka, Doug; Flyer, Natasha; Arge, Charles Bibcode: 2021cosp...43E1736M Altcode: Modeling solar coronal mass ejections (CMEs) is very important for both understanding coronal physics and for improving the accuracy of space weather forecasts. While it is generally accepted that CMEs are primarily magnetic structures, the exact properties of these structures could differ in different models and events. A structure often considered is a spheromak, a toroidal twisted flux rope, which is ejected as a CME bubble. Another commonly considered structure is a twisted magnetic flux rope, which is anchored to the solar surface while its upper portion is ejected into interplanetary space. In this talk we will show how a well-known analytical magnetohydrodynamic CME model (Gibson \& Low, 1998), generally considered a spheromak-like model, can be extended to represent both standard spheromak and twisted flux tube configurations, as well as other topologically distinct magnetic structures. We will begin with the general parameters of the flux rope in this model (such as size and stretching parameters), and explore topologically different congurations possible with their variation. We then present several dimensionless parameters which can be varied to achieve these different configurations and consider how they relate to directly observable quantities. This work is particularly timely, as the Gibson \& Low model is been increasingly used as input to numerical models of the solar corona and the heliosphere. The ability to generate topologically different magnetic congurations within this analytic solution is of great value to such simulations, as well as for the studies of the flux ropes forming in the solar corona. Title: Designing a New Coronal Magnetic Field Energy Diagnostic Authors: Corchado-Albelo, Marcel F.; Dalmasse, Kévin; Gibson, Sarah; Fan, Yuhong; Malanushenko, Anna Bibcode: 2021ApJ...907...23C Altcode: In the solar corona, the free energy, i.e., the excess in magnetic energy over a ground-state potential field, forms the reservoir of energy that can be released during solar flares and coronal mass ejections. Such free energy provides a measure of the magnetic field nonpotentiality. Recent theoretical and observational studies indicate that the presence of nonpotential magnetic fields is imprinted into the structures of infrared, off-limb, coronal polarization. In this paper, we investigate the possibility of exploiting such observations for mapping and studying the accumulation and release of coronal free magnetic energy, with the goal of developing a new tool for identifying "hot spots" of coronal free energy such as those associated with twisted and/or sheared coronal magnetic fields. We applied forward modeling of infrared coronal polarimetry to three-dimensional models of nonpotential and potential magnetic fields. From these we defined a quantitative diagnostic of nonpotentiality that in the future could be calculated from a comparison of infrared, off-limb, coronal polarization observations from, e.g., the Coronal Multi-channel Polarimeter or the Daniel K. Inouye Solar Telescope, and the corresponding polarization signal forward-modeled from a potential field extrapolated from photospheric magnetograms. We considered the relative diagnostic potential of linear and circular polarization, and the sensitivities of these diagnostics to coronal density distributions and assumed boundary conditions of the potential field. Our work confirms the capacity of polarization measurements for diagnosing nonpotentiality and free energy in the solar corona. Title: The Magnetic Skeleton of the Solar Corona Over Several Solar Rotations: Features, Analysis, and Community Availability Authors: Malanushenko, A. V.; Gibson, S. E.; Kucera, T. A.; McKenzie, D. E. Bibcode: 2020AGUFMSH041..02M Altcode: The magnetic field in the solar corona is thought to be the main driver for solar eruptive events, such as flares and coronal mass ejections. The coronal magnetic field is therefore important to study, but it is difficult to measure directly. Usually, it is studied through extrapolations based on photospheric magnetograms. As the corona is thought to be mostly in a state of equilibrium, equations of low-beta equilibria are often used in order to study the structure of the field, or to estimate the magnetic energy. One of the complications that arise from this approach is that the solar photosphere itself is not a low-beta equilibrium.

Images of the solar corona in extreme ultraviolet (EUV) do not directly measure the magnetic field; however, they do reveal structures from which information about magnetic field can be inferred. For example, coronal loops are thought to trace out magnetic field lines, coronal cavities are bounded by magnetic surfaces, coronal holes are areas of magnetic flux that is open to the heliosphere, and plasma flows are also thought to follow lines of magnetic field. In other wavelengths, coronal spectropolarimetry (SP) can provide us with proxies for magnetic field strength and reveal plasma flows along the line of sight, off the limb. The EUV images and SP data are frequently used to validate magnetic field models. Additionally, new models are emerging which can use these data directly as additional constraints.

We aggregate available relevant features seen in EUV and SP data for several solar rotations. We apply existing techniques to infer 3D constraints on the magnetic field from these data. The result is an interactive 3D model based on these constraints for a full rotation, or a "magnetic skeleton". It is modular, so individual constraints can be easily added, or only selected constraints can be used. The features could be exported in either graphical or numerical form. The possible uses of our approach include validation of magnetic models that are based on extrapolations alone. Some models allow for using additional coronal constraints directly. These 'skeletons' can also be used in non-magnetic-modeling applications, as a simple, interactive reference for features seen in a given rotation. We make the models available to the community and show how to obtain and use them. Title: Tracking CME substructure evolution through the solar wind Authors: Gibson, S. E.; DeForest, C.; de Koning, C. A.; Fan, Y.; Malanushenko, A. V.; Merkin, V. G.; Provornikova, E.; Thompson, B. J.; Webb, D. F. Bibcode: 2020AGUFMSH0280005G Altcode: Future coronagraphs and heliospheric imagers, in particular those to be launched on the PUNCH mission, will have the capability to track the evolution of CME substructures as the CME moves through and interacts with the solar wind. We present analysis using polarization data obtained from forward modeling simulations of CMEs in the corona and inner heliosphere. We use these data to track the evolution of substructures in three dimensions, and consider the diagnostic potential of internal substructure vs structure at the front of the CME. In particular, we develop methods for extracting information about chirality of CME magnetic flux ropes from polarization data. Title: Ensemble modeling of interplanetary CMEs with data-constrained internal magnetic flux rope Authors: Provornikova, E.; Merkin, V. G.; Malanushenko, A. V.; Gibson, S. E.; Vourlidas, A.; Arge, C. N. Bibcode: 2020AGUFMSH0030016P Altcode: Understanding the evolution of the CME magnetic structure as it propagates through the interplanetary space is a key aspect in the development of forecasting of magnetic properties of a CME arriving at Earth and thus its impact on space weather. To analyze processes of interplanetary CME (ICME)/solar-wind interactions and the role of CME flux rope specification and solar wind background structure, we take a statistical approach and perform thousands of data-driven MHD simulations of ICME propagation in the inner heliosphere. Data-driven modeling of ICMEs in the inner heliosphere (starting beyond the critical surface in the corona) presents an attractive and computationally feasible approach, since it bypasses the complex problem of CME initiation and eruption in the corona. We simulate the propagation of ICMEs in the inner heliosphere using a global model driven at the coronal boundary by the Wang-Sheeley-Arge (WSA)-ADAPT model. ICMEs are initiated at 21.5 solar radii using an MHD analytical Gibson-Low (G&L) model of a self-similarly expanding magnetic flux rope with defining parameters (e.g., location, magnetic topology, width, magnetic field strength, speed, orientation). The ICME propagation is simulated using the inner heliosphere version of the Grid Agnostic MHD for Extended Research Applications (GAMERA) MHD model, which is a reinvention of the high-heritage Lyon-Fedder-Mobarry (LFM) code. A set of values for each of the defining G&L parameters was constrained by statistical representation of solar CME observations. With the aim to span the solar cycle, we model ICME propagation in different solar wind backgrounds corresponding to rising, maximum, declining and minimum solar cycle phases. A grid of G&L parameters and four solar wind backgrounds constitute a parameter space for thousands of MHD ICME runs. For each of the simulations we extract synthetic in-situ observations of ICME as it passes Earth and synthetic white-light images of an ICME as it propagates in the interplanetary space. We present an analysis of produced distributions of ICME parameters and characteristics. Title: Untangling the global coronal magnetic field with multiwavelength observations Authors: Gibson, S. E.; Malanushenko, A.; de Toma, G.; Tomczyk, S.; Reeves, K.; Tian, H.; Yang, Z.; Chen, B.; Fleishman, G.; Gary, D.; Nita, G.; Pillet, V. M.; White, S.; Bąk-Stęślicka, U.; Dalmasse, K.; Kucera, T.; Rachmeler, L. A.; Raouafi, N. E.; Zhao, J. Bibcode: 2020arXiv201209992G Altcode: Magnetism defines the complex and dynamic solar corona. Coronal mass ejections (CMEs) are thought to be caused by stresses, twists, and tangles in coronal magnetic fields that build up energy and ultimately erupt, hurling plasma into interplanetary space. Even the ever-present solar wind possesses a three-dimensional morphology shaped by the global coronal magnetic field, forming geoeffective corotating interaction regions. CME evolution and the structure of the solar wind depend intimately on the coronal magnetic field, so comprehensive observations of the global magnetothermal atmosphere are crucial both for scientific progress and space weather predictions. Although some advances have been made in measuring coronal magnetic fields locally, synoptic measurements of the global coronal magnetic field are not yet available. We conclude that a key goal for 2050 should be comprehensive, ongoing 3D synoptic maps of the global coronal magnetic field. This will require the construction of new telescopes, ground and space-based, to obtain complementary, multiwavelength observations sensitive to the coronal magnetic field. It will also require development of inversion frameworks capable of incorporating multi-wavelength data, and forward analysis tools and simulation testbeds to prioritize and establish observational requirements on the proposed telescopes. Title: Localized Reconnection Heating Inferred from the Three-dimensional Locations of Bright Active Region Coronal Loops Authors: Longcope, Dana; McCarthy, Marika; Malanushenko, Anna Bibcode: 2020ApJ...901..147L Altcode: Coronal loops observed in soft X-rays and extreme ultraviolet imaging data offer direct evidence that coronal plasma is heated by some mechanism. That mechanism appears to energize a particular bundle of field lines somehow selected from the magnetized coronal volume. Magnetic reconnection localized to a patch within a coronal current sheet is one mechanism that would select a flux bundle at the same time it energized it. Since magnetic reconnection occurs preferentially at topological boundaries, we would expect to find coronal loops concentrated there if it were at work. We explore this hypothesis using a data set, previously compiled by McCarthy et al., consisting of 301 coronal loops interconnecting a pair of active regions over a 48 hr period. That work computed the three-dimensional geometries and magnetic field strengths for most of the loops. This revealed many bright loops lying at the periphery of the interconnecting flux domain, possibly created and energized by the reconnection that created the interconnecting flux. There were, however, many loops well inside the domain which would be difficult to attribute to that mode of reconnection. Here we use detailed magnetic models of the interconnecting domain to show that these internal loops tend to occur along internal boundaries: separatrices. This offers a novel form of evidence that coronal loops are the products of patchy reconnection even under quiescent conditions. Title: Convolutional Neural Networks for Predicting the strength of the Near-Earth Magnetic Field Caused by Interplanetary Coronal Mass Ejections Authors: Malanushenko, Anna; Flyer, Natasha; Gibson, Sarah Bibcode: 2020FrASS...7...62M Altcode: In this paper, we explore the potential of neural networks for making space weather predictions based on near-Sun observations. Our second goal is to determine the extent to which coronal polarimetric observations of erupting structures near the Sun encode sufficient information to predict the impact these structures will have on Earth. We focus on predicting the maximal southward component of the magnetic field ("-Bz") inside an interplanetary coronal mass ejection (ICME) as it impacts the Earth. We use Gibson&Low (G&L) self-similarly expanding flux rope model (Gibson&Low 1998), which allows to consider CMEs with varying location, orientation, size, and morphology. We vary 5 parameters of the model to alter these CME properties, and generate a large database of synthetic CMEs (over 36k synthetic events). For each model CME, we synthesize near-Sun observations, as seen from an observer in quadrature (assuming the CME is directed Earthwards), of either three components of the vector magnetic field ("Experiment 1"), or of synthetic Stokes images, ("Experiment 2"). We then allow the flux rope to expand and record max(-Bz) as the ICME passes 1AU. We further conduct two separate machine learning experiments and develop two different regression-based deep convolutional neural networks (CNNs) to predict max(-Bz) based on these two kinds of the near-Sun input data. Experiment 1 is a proof of concept, to see if a 3-channel CNN (hereafter CNN1), similar to those used in RGB image recognition, can reproduce the results of the self-similar (i.e. scale-invariant) expansion of the G&L model. Experiment 2 is less trivial, as Stokes vector is not linearly related to B, and the line-of-sight integration in the optically thin corona presents additional difficulties for interpreting the signal. This second CNN (hereafter CNN2), although resembling CNN1 in Experiment 1, will have a different number of layers and set of hyperparameters due to a much more complicated mapping between the input and output data. We find that, given vector B, CNN1 can predict max(-Bz) with 97% accuracy, and for the Stokes vector as input, CNN2 can predict max(-Bz) with 95%, both measured in the relative root square error. Title: Evolution of the geoeffective April 5, 2010 CME in the inner heliosphere: A global MHD model with a data-constrained magnetic flux rope specification. Authors: Provornikova, E.; Merkin, V. G.; Gibson, S. E.; Malanushenko, A. V.; Arge, C. N.; Vourlidas, A. Bibcode: 2019AGUFMSH42A..03P Altcode: Modeling the evolution of internal magnetic structure of interplanetary coronal mass ejections (ICMEs) is important both for space weather prediction and for basic understanding of magnetized space plasma interactions. Data-driven modeling of ICMEs in the inner heliosphere (starting beyond the critical surface in the corona) presents an attractive and computationally feasible approach, since it bypasses the complex problem of CME initiation and eruption in the corona. Using this approach, we simulate the propagation of ICMEs through the inner heliosphere using a global model driven at the coronal boundary by the Wang-Sheeley-Arge (WSA)-ADAPT model. ICMEs are initiated at 20 solar radii (Rs) using a magnetohydrodynamic (MHD) analytical Gibson-Low (GL) model of a self-similarly expanding magnetic flux rope with parameters (e.g., location, geometry, speed, orientation) constrained by white-light coronograph observations. The ICME propagation is simulated using the Grid Agnostic MHD for Extended Research Applications (GAMERA) MHD model, which is a recent reinvention of the high-heritage Lyon-Fedder-Mobarry (LFM) code. We apply this approach to the study of a geoeffective ICME which arrived at Earth on April 5, 2010. This ICME appeared bright in SOHO/LASCO and STEREO coronagraphs allowing derivation of its parameters near the Sun thus constraining its properties in our model. However, the orientation of the flux rope was not determined uniquely from the observations. It was also not clear which part of the ICME hit Earth and caused the severe geomagnetic storm. By comparing synthetic white-light images derived from our MHD modeling with images from SOHO/LASCO and STEREO/HI1 and HI2, we shed light on the ICME initial orientation and it evolution due to the interaction with the background solar wind. We further compare the modeling results with ACE observations at 1 AU and discuss which part of the CME was probed by the spacecraft. Title: Gibson & Low Flux Rope Model: More Than a Spheromak! Authors: Malanushenko, A. V.; Gibson, S. E.; Provornikova, E.; Merkin, V. G.; Vourlidas, A.; Arge, C. N.; Dalmasse, K.; Nychka, D. W.; Flyer, N. Bibcode: 2019AGUFMSH11C3397M Altcode: Modeling solar coronal mass ejections (CMEs) is very important for both understanding coronal physics and for improving the accuracy of space weather forecasts. While it is generally accepted that CMEs are primarily magnetic structures, the exact properties of these structures could differ in different models and events. A structure often considered is a spheromak, a toroidal twisted flux rope, which is ejected as a CME bubble. Another commonly considered structure is a twisted magnetic flux rope, which is anchored to the solar surface while its upper portion is ejected into interplanetary space. In this talk we will show how a well-known analytical magnetohydrodynamic CME model (Gibson&Low, 1998), generally considered a spheromak-like model, can be extended to represent both standard spheromak and twisted flux tube configurations, as well as other topologically distinct magnetic structures. We will begin with the general parameters of the flux rope in this model (such as size and stretching parameters), and explore topologically different configurations possible with their variation. We then present several dimensionless parameters which can be varied to achieve these different configurations and consider how they relate to directly observable quantities. This work is particularly timely, as the Gibson&Low model is been increasingly used as input to numerical models of the solar corona and the heliosphere. The ability to generate topologically different magnetic configurations within this analytic solution is of great value to such simulations, as well as for the studies of the flux ropes forming in the solar corona. Title: Measuring and Modeling the Rate of Separator Reconnection between an Emerging and an Existing Active Region Authors: McCarthy, Marika I.; Longcope, Dana W.; Malanushenko, Anna; McKenzie, David E. Bibcode: 2019ApJ...887..140M Altcode: 2019arXiv191106340M Magnetic reconnection occurs when new flux emerges into the corona and becomes incorporated into the existing coronal field. A new active region (AR) emerging in the vicinity of an existing AR provides a convenient laboratory in which reconnection of this kind can be quantified. We use high time-cadence 171 Å data from Solar Dynamics Observatory (SDO)/AIA, focused on new/old active region pair 11147/11149, to quantify reconnection. We identify new loops as brightenings within a strip of pixels between the regions. This strategy is premised on the assumption that the energy responsible for brightening a loop originates in magnetic reconnection. We catalog 301 loops observed in the 48 hr time period beginning with the emergence of AR 11149. The rate at which these loops appear between the two ARs is used to calculate the reconnection rate between them. We then fit these loops with magnetic field, solving for each loop’s field strength, geometry, and twist (via its proxy, coronal α). We find the rate of newly brightened flux overestimates the flux that could be undergoing reconnection. This excess can be explained by our finding that the interconnecting region is not at its lowest energy (constant-α) state; the extrapolations exhibit loop-to-loop variation in α. This flux overestimate may result from the slow emergence of AR 11149, which allows time for Taylor relaxation internal to the domain of the reconnected flux to bring the α distribution toward a single value, providing another mechanism for brightening loops after they are first created. Title: A correlation Study of Coronal EUV Brightenings and Radio Emission Observed by Parker Solar Probe Authors: Martinez Oliveros, J. C.; Pulupa, M.; Malanushenko, A. V.; Guevara Gómez, J. C.; Bale, S.; Bonnell, J. W.; Dudok de Wit, T.; Goetz, K.; Harvey, P.; MacDowall, R. J.; Malaspina, D. Bibcode: 2019AGUFMSH13C3433M Altcode: The dynamic nature of our host star is clearly observable in the solar corona. Different structures are visible in it (coronal loops, streamers, coronal holes), which have a direct relationship with changes that the Sun is experiencing in its interior and photosphere. The morphology of these coronal structures is governed by the magnetic field, but what is more important, the dynamic changes that occur in them are also the product of the magnetic field. One of the consequences of these dynamic changes are solar flares, accompanied by all their manifestations (hard X-ray, EUV, UV, white-light, and radio emissions). Here we present a simple correlation study between EUV brightening observed by the STEREO/EUVI and SDO/AIA instruments and type III radio bursts detected by the FIELDS instrument on-board Parker Solar Probe. We study their possible magnetic connection to the spacecraft and determine the most likely region on the solar corona and photosphere that can be associated with the observed radio emission. Title: Examination of Separator Reconnection Rates in a Series of Adjacent Emerging/Existing Active Region Pairs Authors: McCarthy, M.; Longcope, D. W.; Malanushenko, A. V.; McKenzie, D. E. Bibcode: 2019AGUFMSH11D3387M Altcode: Changes in magnetic field line topology must be occurring when new flux emerges in the solar corona in order for it to become incorporated in the existing coronal field. Magnetic reconnection is the process responsible for this incorporation. We have previously quantified this process using a system in which a new active region (AR) emerges in the vicinity of an existing one by cataloging the loops formed between them. We make a spatial/temporal stack plot of the region between the ARs by extracting the pixels along a virtual slit. A persistent, bright streak in such a plot indicates a coronal loop connecting the newly emerging flux to the existing AR. We assert that loops formed post-emergence between the ARs are initially the result of reconnection. This work presents an extension of our data set to include 12 new emergence events using high time-cadence data from SDO/AIA. Our data set includes several events in which no reconnected loops seem to form between the two ARs. We present an improved method of our loop cataloging procedure. Previous studies of such events have both under and over-sampled the expected reconnected flux formed between the two regions, and included a variety of delays between the emergence of the new AR and the onset of reconnection. To elucidate such discrepancies, we fit loops using a linear force-free field (LFFF) model which we then use to construct a full, non-linear force-free field (NLFFF) model of the system.

This work was supported by NASA's HGI program. Title: Convolutional Neural Networks for Predicting The Impact of Interplanetary Coronal Mass Ejections on The Near-Earth Magnetic Field Authors: Flyer, N.; Malanushenko, A. V.; Gibson, S. E. Bibcode: 2019AGUFMSH34B..07F Altcode: We present a convolutional neural network (CNN) for predicting the maximal amplitude of southward component of the near-Earth magnetic field near from a passing interplanetary coronal mass ejection (iCME). The input to the CNN is the Gibson & Low (GLOW) flux rope model (1998) that describes the coronal properties of a CME, where its morphology and position are controlled by 6 parameters. Our ultimate goal is to assess the ability of using a CNN architecture (2D or 3D) as an emulator of the physical processes operating on the CME between the Sun and Earth. The GLOW model is used as a first, simple test of a self-similarly expanding flux rope. It is the input to numerical simulations of CMEs propagating in the solar wind, in particular APL's Gamera code which uses GLOW as an input. The CNN problem is set up in two phases: 1) given input data near Sun, sets of three 2D images in the meridional plane, of the components magnetic field B: Bx, By, Bz, predict the maximal southward amplitude of the measured Bz at the Earth; 2) given line-of-sight integrated images of the Stokes parameters, U/I, V/I, Q/I, corresponding to the physical configuration in part 1, predict the maximal southward amplitude of the measured Bz at the Earth. Results will be presented for these two different CNN configurations. Title: A comprehensive three-dimensional radiative magnetohydrodynamic simulation of a solar flare Authors: Cheung, M. C. M.; Rempel, M.; Chintzoglou, G.; Chen, F.; Testa, P.; Martínez-Sykora, J.; Sainz Dalda, A.; DeRosa, M. L.; Malanushenko, A.; Hansteen, V.; De Pontieu, B.; Carlsson, M.; Gudiksen, B.; McIntosh, S. W. Bibcode: 2019NatAs...3..160C Altcode: 2018NatAs...3..160C Solar and stellar flares are the most intense emitters of X-rays and extreme ultraviolet radiation in planetary systems1,2. On the Sun, strong flares are usually found in newly emerging sunspot regions3. The emergence of these magnetic sunspot groups leads to the accumulation of magnetic energy in the corona. When the magnetic field undergoes abrupt relaxation, the energy released powers coronal mass ejections as well as heating plasma to temperatures beyond tens of millions of kelvins. While recent work has shed light on how magnetic energy and twist accumulate in the corona4 and on how three-dimensional magnetic reconnection allows for rapid energy release5,6, a self-consistent model capturing how such magnetic changes translate into observable diagnostics has remained elusive. Here, we present a comprehensive radiative magnetohydrodynamics simulation of a solar flare capturing the process from emergence to eruption. The simulation has sufficient realism for the synthesis of remote sensing measurements to compare with observations at visible, ultraviolet and X-ray wavelengths. This unifying model allows us to explain a number of well-known features of solar flares7, including the time profile of the X-ray flux during flares, origin and temporal evolution of chromospheric evaporation and condensation, and sweeping of flare ribbons in the lower atmosphere. Furthermore, the model reproduces the apparent non-thermal shape of coronal X-ray spectra, which is the result of the superposition of multi-component super-hot plasmas8 up to and beyond 100 million K. Title: Radiative MHD Simulation of a Solar Flare Authors: Cheung, Mark; Rempel, Matthias D.; Chintzoglou, Georgios; Chen, Feng; Testa, Paola; Martinez-Sykora, Juan; Sainz Dalda, Alberto; DeRosa, Marc L.; Malanushenko, Anna; Hansteen, Viggo; Carlsson, Mats; De Pontieu, Bart; Gudiksen, Boris; McIntosh, Scott W. Bibcode: 2019AAS...23431005C Altcode: We present a radiative MHD simulation of a solar flare. The computational domain captures the near-surface layers of the convection zone and overlying atmosphere. Inspired by the observed evolution of NOAA Active Region (AR) 12017, a parasitic bipolar region is imposed to emerge in the vicinity of a pre-existing sunspot. The emergence of twisted magnetic flux generates shear flows that create a pre-existing flux rope underneath the canopy field of the sunspot. Following erosion of the overlying bootstrapping field, the flux rope erupts. Rapid release of magnetic energy results in multi-wavelength synthetic observables (including X-ray spectra, narrowband EUV images, Doppler shifts of EUV lines) that are consistent with flare observations. This works suggests the super-position of multi-thermal, superhot (up to 100 MK) plasma may be partially responsible for the apparent non-thermal shape of coronal X-ray sources in flares. Implications for remote sensing observations of other astrophysical objects is also discussed. This work is an important stepping stone toward high-fidelity data-driven MHD models. Title: Measuring and modeling the rate of separator reconnection between an emerging and existing active region Authors: McCarthy, Marika; Longcope, Dana; Malanushenko, Anna; McKenzie, David Eugene Bibcode: 2019AAS...23411705M Altcode: Magnetic reconnection must occur when new flux emerges into the corona and becomes incorporated into the existing coronal field. A new active region (AR) emerging in the vicinity of an existing AR provides a convenient laboratory in which reconnection of this kind can be quantified. We perform such a measurement using high time-cadence 171 Å data from SDO/AIA of active region NOAA AR11149 which emerged in the vicinity of AR11147 beginning on 20 January 2011. We make a spatial/temporal stack plot of the region between the ARs by extracting the pixels along a virtual slit. A persistent, bright streak in such a plot indicates a bright coronal loop connecting the newly emerging flux to the existing AR. This loop must have been formed through a process of coronal reconnection across the separator separating the four topologically distinct flux systems. We assume further that energy released during that reconnection is responsible for its brightening. We catalog 205 loops observed in the a 48-hour time period beginning with the emergence of AR 11149. The rate at which new magnetic flux appears is used to calculate the rate of separator reconnection. We can further fit these cataloged field lines using a linear force-free field (LFFF) extrapolation, solving for an individual loop's field strength and twist. Ultimately, we find the rate of newly-brightened flux overestimates the flux which could be undergoing reconnection. This excess can be explained by our finding that the interconnecting region is not at its lowest energy (constant-α) state; the LFFF modeling shows a variation in values of α. This overestimate might be the result of the region's unusually slow emergence, providing time for internal Taylor-relaxation reconnection of the interconnecting flux following its initial formation by reconnection. We support this hypothesis by computing the rates of brightening within the plane of the virtual slit. This work was supported by NASA's HGI program. Title: MHD modeling of evolving ICME magnetic structure in the inner heliosphere Authors: Provornikova, Elena; Merkin, Vyacheslav; Malanushenko, Anna; Gibson, Sarah; Arge, Nick; Vourlidas, Angelos Bibcode: 2019shin.confE.230P Altcode: As CME propagates through the inner heliosphere, evolution of its structure is influenced by the interaction with the solar wind streams. I will present our recent simulations with GAMERA code of propagating flux rope-CME from 0.1 to 1 AU in the background solar wind. We evaluate self-similarly an erupting CME at 0.1 AU based on the Gibson-Low model and insert it into our global inner heliosphere model driven by the Wang-Sheeley-Arge (WSA) model of the corona, while WSA, in turn, is driven by ADAPT global photospheric magnetic field maps. To simulate the ICME propagation in the inner heliosphere, we use the GAMERA (Grid Agnostic MHD for Extended Research Applications) magnetohydrodynamic (MHD) code which is a reinvention of the high-heritage Lyon-Fedder-Mobarry (LFM) code. We present modeling results and focus on the evolution of the large-scale structure of the CME from the outer solar corona to Earth. In particular I will present a simulation of the April 3, 2010 CME event. Title: Coronal Mass Ejections from Sun to Earth: Recent Advances in Modeling and Statistical Approaches Authors: Malanushenko, Anna; Gibson, S.; Dalmasse, K.; Merkin, V.; Provornikova, E.; Vourlidas, A.; Arge, C.; Nychka, D.; Wiltberger, M.; Flyer, N. Bibcode: 2019shin.confE.206M Altcode: Solar coronal mass ejections (CMEs) are violent eruptive phenomena which originate on the Sun; their heliospheric extensions, called interplanetary CMEs, are known for their potential to impact the whole heliosphere and, in particular, the Earth. While not all CMEs are launched in such a way as to hit the Earth, those that do can have big impacts on Earth's magnetosphere. The magnitude of such impact depends upon many factors such as the CME launch location and velocity, its positioning within the background solar wind, its mass, and its magnetic properties such as the orientation of its front with respect to the Earth's magnetic field.

Case studies of how iCMEs propagate through the heliosphere are complicated by many factors, including often incomplete input for models. We present and discuss a different approach. Rather than focusing on modeling a particular event, we intend to carry out a large statistical study in the event parameter space. Further, Bayesian statistics will be used along with large statistical databases of near-Sun and near-Earth observables, to infer statistical distributions of relevant CME input parameters, which are capable of yielding given distributions of observables, for a given stage of the the solar cycle.

We use a analytical flux rope model (Gibson&Low model) and a background solar wind boundary (Wang-Sheeley-Arge model) as inputs for a new MHD heliospheric simulation code (Gamera). We give an overview and update of the project and show first modeling results. Title: "Building a Magnetic Skeleton of the Solar Corona: Towards Better 3-D Constraints on the Coronal Magnetic Field Authors: Malanushenko, Anna; Gibson, Sarah; Kucera, Therese; McKenzie, David Bibcode: 2018cosp...42E2139M Altcode: The energy stored in the solar magnetic field is what is powering many violent explosive events in the solar atmosphere, or the corona. Some of these events result in the coronal mass ejections (CME's) released into the interplanetary space. The magnetic field in the solar corona is therefore very important to know, yet it is very difficult to measure. Most of the time it is modeled with the magnetic maps at the solar surface used as boundary conditions. The magnetic maps on the surface are therefore also important to know, yet the full vector of the field on the surface is also difficult to measure. Once such measurements are made, constructing a model capable of predicting eruptive potential of a given region is on its own a complicated task. One of the problems arising is that that the equations for low-beta equilibria, which are often used to describe the coronal field, do not, strictly speaking, work for the solar surface. In short, we need better inputs to model the solar corona. The use of non-magnetic and non-surface constraints on the magnetic field becomes increasingly popular. For example, the paths of filaments can be used to guide flux rope trajectories; the loops of active regions, seen in extreme ultraviolet (EUV) can be used to obtain 3-D trajectories of magnetic field lines and estimate electric currents flowing along them. We are currently exploring ways to use other sources of data, such as flows in prominences and coronal spectropolarimetric data, in a similar fashion. I will talk about this work, and about our project of aggregating many different sources of non-magnetic 3-D constraints on the magnetic field. The resulting 'skeleton' can be used to constraint global field models, or to validate models obtained in traditional ways. We intend to develop a pipeline and assemble several skeletons for several instances in time of the Sun, which we will then release to community. Title: Global Solar Magnetic Field Evolution Over 4 Solar Cycles: Use of the McIntosh Archive Authors: Webb, David F.; Gibson, Sarah E.; Hewins, Ian M.; McFadden, Robert H.; Emery, Barbara A.; Malanushenko, Anna; Kuchar, Thomas A. Bibcode: 2018FrASS...5...23W Altcode: The McIntosh Archive consists of a set of hand-drawn solar Carrington maps created by Patrick McIntosh from 1964 to 2009. McIntosh used mainly Hα, He-I 10830Å and photospheric magnetic measurements from both ground-based and NASA satellite observations. With these he traced polarity inversion lines (PILs), filaments, sunspots and plage and, later, coronal holes over a 45-year period. This yielded a unique record of synoptic maps of features associated with the large-scale solar magnetic field over four complete solar cycles. We first discuss how these and similar maps have been used in the past to investigate long-term solar variability. Then we describe our work in preserving and digitizing this archive, developing a digital, searchable format, and creating a website and an archival repository at NOAA's National Centers for Environmental Information (NCEI). Next we show examples of how the data base can be utilized for scientific applications. Finally, we present some preliminary results on the solar-cycle evolution of the solar magnetic field, including the polar field reversal process, the evolution of active longitudes, and the role of differential solar rotation. Title: Vector Magnetograms - From Photosphere to the Base of the Solar Corona Authors: Malanushenko, Anna V.; Rempel, Matthias; Cheung, Chun Ming Mark Bibcode: 2018tess.conf20234M Altcode: The magnetic field in solar active regions is currently a major topic of research in solar physics. While hard to measure directly, it is commonly modeled with the use of photospheric magnetograms. An assumption that is often made in such modeling is that the plasma beta is small in the rarefied corona and therefore an equilibrium configuration requires that the Lorentz force vanishes through the volume. While this assumption greatly simplifies the modeling, it also complicates the use of the photospheric magnetic field as a boundary condition, as the photosphere is not in general a low-beta environment. While vector magnetograms at the base of the low-beta corona are not routinely available, the photospheric magnetograms continue to be widely used for coronal modeling. Additional steps, such as pre-processing, can be taken during the modeling to make these data as consistent with the low-beta equilibria as possible. In this work, we attempt to analyze how much do magnetograms of the coronal base differ from those of the photosphere, analyze their morphology, magnitude and how they change with height. For this, we analyze some of the most realistic full-MHD simulations of active regions made with MURaM code. They simulation volume includes upper convection zone, photosphere, transition region, and the corona. While they are not simulations of a specific active region, they appear extremely realistic in wide range of diagnostics, from the magnetic field in the photosphere, to the coronal morphology, to evolution typically observed in active regions. We study these simulations and the synthetic data they produce, focusing on the applicability of vector magnetograms to low-beta coronal magnetic modeling. We also describe some alternative methods of gathering vector magnetograms of the chromosphere from the coronal morphology, and compare them to the actual structures of the simulations. Title: Measuring separator reconnection between emerging and existing active regions using extreme ultraviolet imaging observations Authors: McCarthy, Marika; Longcope, Dana; McKenzie, David E.; Malanushenko, Anna V. Bibcode: 2018tess.conf20545M Altcode: Magnetic reconnection must be occurring when new flux emerges into the corona, in order that the flux become incorporated into the existing corona. The most evident, and easily quantified, example of this occurs when a new active region (AR) emerges in the vicinity of an existing AR. In a study of such emergence observed by TRACE, Longcope et al. (2005) found a delay of approximately 24 hours between the new AR emerging and its reconnection with the field of the existing AR. This turned out to be the only suitable event in the TRACE archive. Here we apply the same method to events observed by SDO/AIA. Using high time-cadence images in one EUV wavelength, such as 171 A, we make a spatial/temporal stack plot of the region between the ARs by extracting the pixel in a virtual slit. A persistent, bright streak indicates a bright coronal loop connecting the newly emerging flux to the existing AR. This loop must have been formed through a process of coronal reconnection across the separator separating the two flux systems. The rate at which new loops appear is used to compute the rate of separator reconnection. The continuous, high-cadence data from AIA permits flux transfer to be quantified for intervals exceeding 48 hours.

This work was supported by NASA's HGI program. Title: Studies of Global Solar Magnetic Field Patterns Using a Newly Digitized Archive Authors: Hewins, I.; Webb, D. F.; Gibson, S. E.; McFadden, R.; Emery, B. A.; Malanushenko, A. V. Bibcode: 2017AGUFMSH54A..01H Altcode: The McIntosh Archive consists of a set of hand-drawn solar Carrington maps created by Patrick McIntosh from 1964 to 2009. McIntosh used mainly Ha, He 10830Å and photospheric magnetic measurements from both ground-based and NASA satellite observations. With these he traced polarity inversion lines (PILs), filaments, sunspots and plage and, later, coronal holes, yielding a unique 45-year record of features associated with the large-scale organization of the solar magnetic field. We discuss our efforts to preserve and digitize this archive; the original hand-drawn maps have been scanned, a method for processing these scans into digital, searchable format has been developed, and a website and an archival repository at NOAA's National Centers for Environmental Information (NCEI) has been created. The archive is complete for SC 23 and partially complete for SCs 21 and 22. In this paper we show examples of how the data base can be utilized for scientific applications. We compare the evolution of the areas and boundaries of CHs with other recent results, and we use the maps to track the global, SC-evolution of filaments, large-scale positive and negative polarity regions, PILs and sunspots. Title: The McIntosh Archive: A solar feature database spanning four solar cycles Authors: Gibson, S. E.; Malanushenko, A. V.; Hewins, I.; McFadden, R.; Emery, B.; Webb, D. F.; Denig, W. F. Bibcode: 2016AGUFMSH11A2220G Altcode: The McIntosh Archive consists of a set of hand-drawn solar Carrington maps created by Patrick McIntosh from 1964 to 2009. McIntosh used mainly H-alpha, He-1 10830 and photospheric magnetic measurements from both ground-based and NASA satellite observations. With these he traced coronal holes, polarity inversion lines, filaments, sunspots and plage, yielding a unique 45-year record of the features associated with the large-scale solar magnetic field. We will present the results of recent efforts to preserve and digitize this archive. Most of the original hand-drawn maps have been scanned, a method for processing these scans into digital, searchable format has been developed and streamlined, and an archival repository at NOAA's National Centers for Environmental Information (NCEI) has been created. We will demonstrate how Solar Cycle 23 data may now be accessed and how it may be utilized for scientific applications. In addition, we will discuss how this database of human-recognized features, which overlaps with the onset of high-resolution, continuous modern solar data, may act as a training set for computer feature recognition algorithms. Title: Distortions of Magnetic Flux Tubes in the Presence of Electric Currents Authors: Malanushenko, Anna; Rempel, Matthias; Cheung, Mark Bibcode: 2016SPD....47.0322M Altcode: Solar coronal loops possess several peculiar properties, which have been a subject of intensive research for a long time. These in particular include the lack of apparent expansion of coronal loops and the increased pressure scale height in loops compared to the diffuse background. Previously, Malanushenko & Schrijver (2013) proposed that these could be explained by the fact that magnetic flux tubes expand with height in a highly anisotropic manner. They used potential field models to demonstrate that flux tubes that have circular cross section at the photosphere, in the corona turn into a highly elongates structures, more resembling thick ribbons. Such ribbons, viewed along the expanding edge, would appear as thin, crisp structures of a constant cross-section with an increased pressure scale height, and when viewed along the non-expanding side, would appear as faint, wide and underdense features. This may also introduce a selection bias,when a set of loops is collected for a further study, towards those viewed along the expanding edge.However, some of the past studies have indicated that strong electric currents flowing in a given flux tube may result in the tube maintaining a relatively constant cross-sectional shape along its length. Given that Malanushenko & Schrijver (2013) focused on a potential, or current-free, field model of an active region, the extend to which their analysis could be applied to the real solar fields, was unclear.In the present study, we use a magnetic field created by MURaM, a highly realistic state-of-the-art radiative MHD code (Vogler et al, 2005; Rempel et al, 2009b). MURaM was shown to reproduce a wide variety of observed features of the solar corona (e.g., Hansteen et al, 2010; Cheung et al. 2007, 2008; Rempel 2009a,b). We analyze the distortions of magnetic flux tubes in a MURaM simulation of an active region corona. We quantify such distortions and correlate them with a number of relevant parameters of flux tubes, with a particular emphasis on the electric currents in the simulated corona. Title: Coronal Heating: Testing Models of Coronal Heating by Forward-Modeling the AIA Emission of the Ansample of Coronal Loops Authors: Malanushenko, A. V. Bibcode: 2015AGUFMSH31B2423M Altcode: We present a systemic exploration of the properties of coronal heating, by forward-modeling the emission of the ensemble of 1D quasi-steady loops. This approximations were used in many theoretical models of the coronal heating. The latter is described in many such models in the form of power laws, relating heat flux through the photosphere or volumetric heating to the strength of the magnetic field and length of a given field line. We perform a large search in the parameter space of these power laws, amongst other variables, and compare the resulting emission of the active region to that observed by AIA. We use a recently developed magnetic field model which uses shapes of coronal loops to guide the magnetic model; the result closely resembles observed structures by design. We take advantage of this, by comparing, in individual sub-regions of the active region, the emission of the active region and its synthetic model. This study allows us to rule out many theoretical models and formulate predictions for the heating models to come. Title: The Influence of Spatial resolution on Nonlinear Force-free Modeling Authors: DeRosa, M. L.; Wheatland, M. S.; Leka, K. D.; Barnes, G.; Amari, T.; Canou, A.; Gilchrist, S. A.; Thalmann, J. K.; Valori, G.; Wiegelmann, T.; Schrijver, C. J.; Malanushenko, A.; Sun, X.; Régnier, S. Bibcode: 2015ApJ...811..107D Altcode: 2015arXiv150805455D The nonlinear force-free field (NLFFF) model is often used to describe the solar coronal magnetic field, however a series of earlier studies revealed difficulties in the numerical solution of the model in application to photospheric boundary data. We investigate the sensitivity of the modeling to the spatial resolution of the boundary data, by applying multiple codes that numerically solve the NLFFF model to a sequence of vector magnetogram data at different resolutions, prepared from a single Hinode/Solar Optical Telescope Spectro-Polarimeter scan of NOAA Active Region 10978 on 2007 December 13. We analyze the resulting energies and relative magnetic helicities, employ a Helmholtz decomposition to characterize divergence errors, and quantify changes made by the codes to the vector magnetogram boundary data in order to be compatible with the force-free model. This study shows that NLFFF modeling results depend quantitatively on the spatial resolution of the input boundary data, and that using more highly resolved boundary data yields more self-consistent results. The free energies of the resulting solutions generally trend higher with increasing resolution, while relative magnetic helicity values vary significantly between resolutions for all methods. All methods require changing the horizontal components, and for some methods also the vertical components, of the vector magnetogram boundary field in excess of nominal uncertainties in the data. The solutions produced by the various methods are significantly different at each resolution level. We continue to recommend verifying agreement between the modeled field lines and corresponding coronal loop images before any NLFFF model is used in a scientific setting. Title: Blind Stereoscopy of the Coronal Magnetic Field Authors: Aschwanden, Markus J.; Schrijver, Carolus J.; Malanushenko, Anna Bibcode: 2015SoPh..290.2765A Altcode: 2015SoPh..tmp..147A; 2015arXiv150604713A We test the feasibility of 3D coronal-loop tracing in stereoscopic EUV image pairs, with the ultimate goal of enabling efficient 3D reconstruction of the coronal magnetic field that drives flares and coronal mass ejections (CMEs). We developed an automated code designed to perform triangulation of coronal loops in pairs (or triplets) of EUV images recorded from different perspectives. The automated (or blind) stereoscopy code includes three major tasks: i) automated pattern recognition of coronal loops in EUV images, ii) automated pairing of corresponding loop patterns from two different aspect angles, and iii) stereoscopic triangulation of 3D loop coordinates. We perform tests with simulated stereoscopic EUV images and quantify the accuracy of all three procedures. In addition we test the performance of the blind-stereoscopy code as a function of the spacecraft-separation angle and as a function of the spatial resolution. We also test the sensitivity to magnetic non-potentiality. The automated code developed here can be used for analysis of existing Solar TErrestrial RElationship Observatory (STEREO) data, but primarily serves for a design study of a future mission with dedicated diagnostics of non-potential magnetic fields. For a pixel size of 0.6″ (corresponding to the Solar Dynamics Observatory (SDO)/Atmospheric Imaging Assembly (AIA) spatial resolution of 1.4″), we find an optimum spacecraft-separation angle of αs≈5∘. Title: Thermal Diagnostics with the Atmospheric Imaging Assembly on board the Solar Dynamics Observatory: A Validated Method for Differential Emission Measure Inversions Authors: Cheung, Mark C. M.; Boerner, P.; Schrijver, C. J.; Testa, P.; Chen, F.; Peter, H.; Malanushenko, A. Bibcode: 2015ApJ...807..143C Altcode: 2015arXiv150403258C We present a new method for performing differential emission measure (DEM) inversions on narrow-band EUV images from the Atmospheric Imaging Assembly (AIA) on board the Solar Dynamics Observatory. The method yields positive definite DEM solutions by solving a linear program. This method has been validated against a diverse set of thermal models of varying complexity and realism. These include (1) idealized Gaussian DEM distributions, (2) 3D models of NOAA Active Region 11158 comprising quasi-steady loop atmospheres in a nonlinear force-free field, and (3) thermodynamic models from a fully compressible, 3D MHD simulation of active region (AR) corona formation following magnetic flux emergence. We then present results from the application of the method to AIA observations of Active Region 11158, comparing the region's thermal structure on two successive solar rotations. Additionally, we show how the DEM inversion method can be adapted to simultaneously invert AIA and Hinode X-ray Telescope data, and how supplementing AIA data with the latter improves the inversion result. The speed of the method allows for routine production of DEM maps, thus facilitating science studies that require tracking of the thermal structure of the solar corona in time and space. Title: MHD Simulations of the Evolution of the Coronal Magnetic Field: First Steps in Using the Realistic Initial State Model Authors: Malanushenko, Anna V.; Fan, Yuhong Bibcode: 2015TESS....120312M Altcode: We present the first results of simulations of a realistic coronal magnetic field evolution. The initial state of the field is a non-linear force-free model (NLFFF) which matches the observed coronal features by design (see Malanushenko et al, 2012). We evolve this field model using an ideal MHD code (see Fan, 2009). We use the model of AR 11158 shortly before X2.2 class flare on February 15th. This model was shown by Malanushenko et al (2014) to possess both the correct morphology of the coronal field (compared to the EUV images), and free magnetic energy sufficient for a flare of this class. We demonstrate stability of the twisted current bundle in the core of the region when no photospheric driving is present, and the first results of the evolution of the model corona when the photospheric driving roughly corresponds to that observed at the photosphere. Title: Time Evolution of Force-Free Parameter and Free Magnetic Energy in Active Region NOAA 10365 Authors: Valori, G.; Romano, P.; Malanushenko, A.; Ermolli, I.; Giorgi, F.; Steed, K.; van Driel-Gesztelyi, L.; Zuccarello, F.; Malherbe, J. -M. Bibcode: 2015SoPh..290..491V Altcode: We describe the variation of the accumulated coronal helicity derived from the magnetic helicity flux through the photosphere in active region (AR) NOAA 10365, where several large flares and coronal mass ejections (CMEs) occurred. We used SOHO/MDI full-disk line-of-sight magnetograms to measure the helicity flux, and the integral of GOES X-ray flux as a proxy of the coronal energy variations due to flares or CMEs. Using the linear force-free field model, we transformed the accumulated helicity flux into a time sequence of the force-free parameter α accounting for flares or CMEs via the proxy derived from GOES observations. This method can be used to derive the value of α at different times during the AR evolution, and is a partial alternative to the commonly used match of field lines with EUV loops. By combining the accumulated helicity obtained from the observations with the linear force-free theory, we describe the main phases of the emergence process of the AR, and relate them temporally with the occurrence of flares or CMEs. Additionally, a comparison with the loop-matching method of fixing alpha at each time independently shows that the proposed method may be helpful in avoiding unrealistic or undetermined values of alpha that may originate from an insufficient quality of the image used to identify coronal loops at a given time. For the relative intensity of the considered events, the linear force-free field theory implies that there is a direct correlation between the released energy on the one hand and the product of the coronal helicity with the variation of α due to the event on the other. Therefore, the higher the value of the accumulated coronal helicity, the smaller the force-free parameter variation required to produce the same decrease in the free energy during the CMEs. Title: Deciphering Solar Magnetic Activity. I. On the Relationship between the Sunspot Cycle and the Evolution of Small Magnetic Features Authors: McIntosh, Scott W.; Wang, Xin; Leamon, Robert J.; Davey, Alisdair R.; Howe, Rachel; Krista, Larisza D.; Malanushenko, Anna V.; Markel, Robert S.; Cirtain, Jonathan W.; Gurman, Joseph B.; Pesnell, William D.; Thompson, Michael J. Bibcode: 2014ApJ...792...12M Altcode: 2014arXiv1403.3071M Sunspots are a canonical marker of the Sun's internal magnetic field which flips polarity every ~22 yr. The principal variation of sunspots, an ~11 yr variation, modulates the amount of the magnetic field that pierces the solar surface and drives significant variations in our star's radiative, particulate, and eruptive output over that period. This paper presents observations from the Solar and Heliospheric Observatory and Solar Dynamics Observatory indicating that the 11 yr sunspot variation is intrinsically tied to the spatio-temporal overlap of the activity bands belonging to the 22 yr magnetic activity cycle. Using a systematic analysis of ubiquitous coronal brightpoints and the magnetic scale on which they appear to form, we show that the landmarks of sunspot cycle 23 can be explained by considering the evolution and interaction of the overlapping activity bands of the longer-scale variability. Title: Forward Modeling of Coronal Emission Authors: Malanushenko, Anna; Schrijver, Carolus J.; Van Ballegooijen, Adriaan A. Bibcode: 2014AAS...22432102M Altcode: In this work, we present simulations of the coronal emission in Extreme Ultraviolet wavelengths, subject to the possible physical models of how the solar corona is heated. In order to maximize the match of the simulations with the observations, we also use models of coronal magnetic field which are constructed to match the observed coronal features (see Malanushenko et al, 2014). While we utilize the 1D quasi-steady atmosphere approach (as in Schrijver & van Ballegoijen, 2005), we take a step away from the commonly used assumption about circular cross-sections of magnetic flux tubes, as our previous research (Malanushenko & Schrijver, 2013) suggests that this assumption might lead to substantial artefacts when comparing the simulations to the observations. In this work, we explore how such treatment of magnetic flux tubes is capable of producing realistic coronal features. Using these two major advances, the realistic field model and the realistic treatment of the cross-section of flux tubes, we test a wide range of possible heating scenarios, ruling out possibilities by comparing the simulations with data from a wide range of EUV channels onboard SDO/AIA spacecraft. Title: Active region 11748: Recurring X-class flares, large scale dimmings and waves. Authors: Davey, Alisdair R.; Malanushenko, Anna; McIntosh, Scott W. Bibcode: 2014AAS...22421818D Altcode: AR 11748 was a relatively compact active region that crossed the solar disk between 05/14/2013 and 05/26/2013. Despite its size it produced a number X-class flares, and global scale eruptive events that were captured by the SDO Feature Finding Team's (FFT) Dimming Region Detector. Using the results of this module and other FFT modules, we present an analysis of the this AR region and investigate why it was so globally impactful. Title: Active Region Magnetic Field Modeling Guided by Coronal Loops and Surface Fields Authors: DeRosa, Marc L.; Malanushenko, Anna; Schrijver, Carolus J.; Wheatland, Michael S Bibcode: 2014AAS...22432319D Altcode: Dynamic events such as solar flares, filament eruptions, and mass ejections are powered by the evolving coronal magnetic field. However, the ways in which energy is stored in, and released from, the coronal magnetic field are poorly understood, in large part because the field configuration cannot be determined directly from observations and has eluded the successful application of routine modeling based on surface magnetograms. Recently, we have demonstrated that the Quasi-Grad-Rubin (QGR) method for modeling the current-carrying field associated with active regions shows promise. In Malanushenko et al. (2014, ApJ 783:102) we have used the QGR method to construct the magnetic field at several times during the evolution of AR11158 during February 2011. The QGR method does not require vector magnetograms, and instead uses the trajectories of observed coronal loops to constrain the locations of electric currents within the modeling domain. In this study, we continue to assess the utility of QGR by applying this method to additional active regions from the current activity cycle, making use of SDO/HMI line-of-sight magnetograms and imagery from the extreme ultraviolet channels of SDO/AIA. Title: Using Coronal Loops to Reconstruct the Magnetic Field of an Active Region before and after a Major Flare Authors: Malanushenko, A.; Schrijver, C. J.; DeRosa, M. L.; Wheatland, M. S. Bibcode: 2014ApJ...783..102M Altcode: 2013arXiv1312.5389M The shapes of solar coronal loops are sensitive to the presence of electrical currents that are the carriers of the non-potential energy available for impulsive activity. We use this information in a new method for modeling the coronal magnetic field of active region (AR) 11158 as a nonlinear force-free field (NLFFF). The observations used are coronal images around the time of major flare activity on 2011 February 15, together with the surface line-of-sight magnetic field measurements. The data are from the Helioseismic and Magnetic Imager and Atmospheric Imaging Assembly on board the Solar Dynamics Observatory. The model fields are constrained to approximate the coronal loop configurations as closely as possible, while also being subject to the force-free constraints. The method does not use transverse photospheric magnetic field components as input and is thereby distinct from methods for modeling NLFFFs based on photospheric vector magnetograms. We validate the method using observations of AR 11158 at a time well before major flaring and subsequently review the field evolution just prior to and following an X2.2 flare and associated eruption. The models indicate that the energy released during the instability is about 1 × 1032 erg, consistent with what is needed to power such a large eruptive flare. Immediately prior to the eruption, the model field contains a compact sigmoid bundle of twisted flux that is not present in the post-eruption models, which is consistent with the observations. The core of that model structure is twisted by ≈0.9 full turns about its axis. Title: Using coronal loops to model the coronal magnetic field before and after major eruptive events Authors: Malanushenko, Anna; Schrijver, Carolus; Wheatland, M. S.; DeRosa, Marc Bibcode: 2014cosp...40E1960M Altcode: Solar flares are believed to be a manifestation of major release of magnetic energy stored in active region field. Modeling the coronal magnetic field may enable us to evaluate the energy available for release, as well as possible sites of the reconnection and other relevant properties of the field. We use a new method to aid this problem by including the observed structure of the field (manifested in coronal loops) as additional constraints. We verify that the method (previously shown to work on synthetic data in Malanushenko et. al., ApJ, 756, 153, 2012) is generally acceptable for the solar data, as it gives self-consistent, slowly changing results for slowly evolving structures. We further develop the potential of this method to access changes in the coronal magnetic field triggered by major eruptive events, and compare the results with observations. Title: On the Anisotropy in Expansion of Magnetic Flux Tubes in the Solar Corona Authors: Malanushenko, A.; Schrijver, C. J. Bibcode: 2013ApJ...775..120M Altcode: 2013arXiv1307.3440M Most one-dimensional hydrodynamic models of plasma confined to magnetic flux tubes assume circular tube cross sections. We use potential field models to show that flux tubes in circumstances relevant to the solar corona do not, in general, maintain the same cross-sectional shape through their length and therefore the assumption of a circular cross section is rarely true. We support our hypothesis with mathematical reasoning and numerical experiments. We demonstrate that lifting this assumption in favor of realistic, non-circular loops makes the apparent expansion of magnetic flux tubes consistent with that of observed coronal loops. We propose that in a bundle of ribbon-like loops, those that are viewed along the wide direction would stand out against those that are viewed across the wide direction due to the difference in their column depths. That result would impose a bias toward selecting loops that appear not to be expanding, seen projected in the plane of sky. An implication of this selection bias is that the preferentially selected non-circular loops would appear to have increased pressure scale heights even if they are resolved by current instruments. Title: A Nonlinear Force-Free Magnetic Field Approximation Suitable for Fast Forward-Fitting to Coronal Loops. II. Numeric Code and Tests Authors: Aschwanden, Markus J.; Malanushenko, Anna Bibcode: 2013SoPh..287..345A Altcode: 2012arXiv1207.2783A; 2012SoPh..tmp..182A Based on a second-order approximation of nonlinear force-free magnetic field solutions in terms of uniformly twisted field lines derived in Paper I, we develop here a numeric code that is capable to forward-fit such analytical solutions to arbitrary magnetogram (or vector magnetograph) data combined with (stereoscopically triangulated) coronal loop 3D coordinates. We test the code here by forward-fitting to six potential field and six nonpotential field cases simulated with our analytical model, as well as by forward-fitting to an exactly force-free solution of the Low and Lou (Astrophys. J.352, 343, 1990) model. The forward-fitting tests demonstrate: i) a satisfactory convergence behavior (with typical misalignment angles of μ≈1∘ - 10∘), ii) relatively fast computation times (from seconds to a few minutes), and iii) the high fidelity of retrieved force-free α-parameters (αfit/αmodel≈0.9 - 1.0 for simulations and αfit/αmodel≈0.7±0.3 for the Low and Lou model). The salient feature of this numeric code is the relatively fast computation of a quasi-force-free magnetic field, which closely matches the geometry of coronal loops in active regions, and complements the existing nonlinear force-free field (NLFFF) codes based on photospheric magnetograms without coronal constraints. Title: On Cross-Sectional Properties of Coronal Loops Authors: Malanushenko, Anna; Schrijver, C. J. Bibcode: 2013SPD....4420105M Altcode: Coronal loops have been observed for several decades, yet some of their properties remain a mystery. These in particular include the lack of apparent expansion of coronal loops and the increased pressure scale height in loops compared to the diffuse background. We approach these problems in an entirely new way. We demonstrate that solely lifting the assumption about circular cross-sectional shape of flux tubes is alone sufficient to explain lack of expansion and increased pressure scale height. While magnetic flux tubes expand in the corona, they do so in a highly anisotropic manner, which we examine in details for several model fields and quantify for a potential field model based on HMI data. We demonstrate how, and why, this leads towards (1) selection bias which might make some loops stand out if they expand mostly along the line of sight, due to their increased column depth; (2) principal limitations on measuring expansion of coronal loops, even if they are resolved and (3) the apparent increased pressure scale height. We also address the existing studies which seemingly concluded the opposite. The latter was based on several properties of the loops' emission which, as we show, are also reproduced when loops are oblate in cross-section. Title: Modeling coronal loop oscillations in realistic magnetic and density structures Authors: Ofman, Leon; Wang, T.; Malanushenko, A.; Davila, J. M. Bibcode: 2013SPD....4410404O Altcode: Recently, ubiquitous coronal loop oscillations were detected in active region loops by SDO/AIA. Hinode/EIS observations indicate that quasi-periodic flows are present at footpoints of loops in active regions, and related propagating disturbances (PD's) were detected in open and closed loop structures. Recent 3D MHD models in idealized (bipolar) active regions (Ofman et al. 2012; Wang et al. 2013, this meeting) have demonstrated that the flows can produce slow magnetosonic waves in loops, as well as transverse oscillations. We extend the idealized studies by considering more realistic magnetic field structures modeled by including photospheric magnetic field extrapolated to the corona as boundary and initial conditions for the 3D MHD modeling. We use potential and nonlinear magnetic field extrapolations combined with gravitationally stratified density and introduce flows at the corona-transition region boundary in our 3D MHD model. We apply coronal seismology to the resulting loop oscillations and compare to oscillation events detected by SDO/AIA. We aim to improve the accuracy of coronal seismology by modeling coronal loop oscillations in realistic magnetic geometry and density structures. Title: Automated Temperature and Emission Measure Analysis of Coronal Loops and Active Regions Observed with the Atmospheric Imaging Assembly on the Solar Dynamics Observatory (SDO/AIA) Authors: Aschwanden, Markus J.; Boerner, Paul; Schrijver, Carolus J.; Malanushenko, Anna Bibcode: 2013SoPh..283....5A Altcode: 2011SoPh..tmp..384A We developed numerical codes designed for automated analysis of SDO/AIA image datasets in the six coronal filters, including: i) coalignment test between different wavelengths with measurements of the altitude of the EUV-absorbing chromosphere, ii) self-calibration by empirical correction of instrumental response functions, iii) automated generation of differential emission measure [DEM] distributions with peak-temperature maps [Tp(x,y)] and emission measure maps [EMp(x,y)] of the full Sun or active region areas, iv) composite DEM distributions [dEM(T)/dT] of active regions or subareas, v) automated detection of coronal loops, and vi) automated background subtraction and thermal analysis of coronal loops, which yields statistics of loop temperatures [Te], temperature widths [σT], emission measures [EM], electron densities [ne], and loop widths [w]. The combination of these numerical codes allows for automated and objective processing of numerous coronal loops. As an example, we present the results of an application to the active region NOAA 11158, observed on 15 February 2011, shortly before it produced the largest (X2.2) flare during the current solar cycle. We detect 570 loop segments at temperatures in the entire range of log(Te)=5.7 - 7.0 K and corroborate previous TRACE and AIA results on their near-isothermality and the validity of the Rosner-Tucker-Vaiana (RTV) law at soft X-ray temperatures (T≳2 MK) and its failure at lower EUV temperatures. Title: First Three-dimensional Reconstructions of Coronal Loops with the STEREO A+B Spacecraft. IV. Magnetic Modeling with Twisted Force-free Fields Authors: Aschwanden, Markus J.; Wuelser, Jean-Pierre; Nitta, Nariaki V.; Lemen, James R.; DeRosa, Marc L.; Malanushenko, Anna Bibcode: 2012ApJ...756..124A Altcode: 2012arXiv1207.2790A The three-dimensional coordinates of stereoscopically triangulated loops provide strong constraints for magnetic field models of active regions in the solar corona. Here, we use STEREO/A and B data from some 500 stereoscopically triangulated loops observed in four active regions (2007 April 30, May 9, May 19, and December 11), together with SOHO/MDI line-of-sight magnetograms. We measure the average misalignment angle between the stereoscopic loops and theoretical magnetic field models, finding a mismatch of μ = 19°-46° for a potential field model, which is reduced to μ = 14°-19° for a non-potential field model parameterized by twist parameters. The residual error is commensurable with stereoscopic measurement errors (μSE ≈ 8°-12°). We developed a potential field code that deconvolves a line-of-sight magnetogram into three magnetic field components (Bx , By , Bz ), as well as a non-potential field forward-fitting code that determines the full length of twisted loops (L ≈ 50-300 Mm), the number of twist turns (median N twist = 0.06), the nonlinear force-free α-parameter (median α ≈ 4 × 10-11 cm-1), and the current density (median jz ≈ 1500 Mx cm-2 s-1). All twisted loops are found to be far below the critical value for kink instability, and Joule dissipation of their currents is found to be far below the coronal heating requirement. The algorithm developed here, based on an analytical solution of nonlinear force-free fields that is accurate to second order (in the force-free parameter α), represents the first code that enables fast forward fitting to photospheric magnetograms and stereoscopically triangulated loops in the solar corona. Title: Guiding Nonlinear Force-free Modeling Using Coronal Observations: First Results Using a Quasi-Grad-Rubin Scheme Authors: Malanushenko, A.; Schrijver, C. J.; DeRosa, M. L.; Wheatland, M. S.; Gilchrist, S. A. Bibcode: 2012ApJ...756..153M Altcode: 2012arXiv1202.5420M At present, many models of the coronal magnetic field rely on photospheric vector magnetograms, but these data have been shown to be problematic as the sole boundary information for nonlinear force-free field extrapolations. Magnetic fields in the corona manifest themselves in high-energy images (X-rays and EUV) in the shapes of coronal loops, providing an additional constraint that is not at present used as constraints in the computational domain, directly influencing the evolution of the model. This is in part due to the mathematical complications of incorporating such input into numerical models. Projection effects, confusion due to overlapping loops (the coronal plasma is optically thin), and the limited number of usable loops further complicate the use of information from coronal images. We develop and test a new algorithm to use images of coronal loops in the modeling of the solar coronal magnetic field. We first fit projected field lines with those of constant-α force-free fields to approximate the three-dimensional distribution of currents in the corona along a sparse set of trajectories. We then apply a Grad-Rubin-like iterative technique, which uses these trajectories as volume constraints on the values of α, to obtain a volume-filling nonlinear force-free model of the magnetic field, modifying a code and method presented by Wheatland. We thoroughly test the technique on known analytical and solar-like model magnetic fields previously used for comparing different extrapolation techniques and compare the results with those obtained by currently available methods relying only on the photospheric data. We conclude that we have developed a functioning method of modeling the coronal magnetic field by combining the line-of-sight component of the photospheric magnetic field with information from coronal images. Whereas we focus on the use of coronal loop information in combination with line-of-sight magnetograms, the method is readily extended to incorporate vector-magnetic data over any part of the photospheric boundary. Title: Estimate of Energy Release In a Major Flare Using Coronal Loops Data Authors: Malanushenko, Anna; Schrijver, C. J.; DeRosa, M. L. Bibcode: 2012AAS...22052115M Altcode: Coronal loops provide with valuable source of information about coronal magnetic field. In particular, they allow one to observe reconfiguration of the coronal magnetic field during eruptive episodes. The changes in the coronal field, as observed in X-rays and extreme ultraviolet, are often dramatic in even minor eruptions. Therefore, models of magnetic field which take coronal loops into account might provide for new insight at changes of the field during eruptions. We use coronal loops data (gathered from SDO/AIA images) along with the line-of-sight magnetograms (by SDO/HMI) to model magnetic field in AR 11158 before and after the so-called Valentine's Flare, an X-class flare in Feb 15, 2011. This is done using the recently developed Quasi Grad-Rubin algorithm (QGR), which allows a reconstruction of non-linear force-free field based on information about electric currents along a set of arbitrary tracks in the computational domain. Tests of QGR on solar-like fields demonstrate its ability to recover over 50% of the free energy, as well as the large-scale structure of currents and overall shape of field lines. We analyze model magnetic fields of AR 11158 before and after the flare, demonstrate their resemblance with the observed structure of coronal loops and analyze the changes in the structure of currents caused by the flare, and compare our results with existing studies of the same event. Title: Force-Free Magneto-Stereoscopy of Coronal Loops Authors: Aschwanden, Markus J.; Malanushenko, A.; Wuelser, J.; Nitta, N.; Lemen, J. R.; DeRosa, M. Bibcode: 2012AAS...22041103A Altcode: We derive an analytical approximation of nonlinear force-free magnetic field solutions (NLFFF) that can efficiently be used for fast forward-fitting to solar magnetic data, constrained either by observed line-of-sight magnetograms and stereoscopically triangulated coronal loops, or by 3D vector-magnetograph data. We test the code by forward-fitting to simulated data, to force-free solutions derived by Low and Lou (1990), and to active regions observed with STEREO/EUVI and SOHO/MDI. The forward-fitting tests demonstrate: (i) a satisfactory convergence behavior (with typical misalignment angles of 1-10 deg), (ii) a high fidelity of retrieved force-free alpha-parameters, and (iii) relatively fast computation times (from seconds to minutes). The novel feature of this NLFFF code is the derivation of a quasi-forcefree field based on coronal constraints, which bypasses the non-forcefree photosphere of standard magnetograms. Applications range from magnetic modeling of loops to the determnination of electric currents, twist, helicity, and free (non-potential) energy in active regions. Title: Physics of Transient Seismic Emission from Flares Authors: Lindsey, Charles A.; Donea, A.; Malanushenko, A. Bibcode: 2012AAS...22020409L Altcode: We consider the physics of seismic activity in solar flares, i.e., the release of powerful seismic transients into the solar interior during the impulsive phases of some flares. Recent work by Hudson, Fisher, Welsch and Bercik has attracted a great deal of positive attention to the possible role of Lorentz-force transients in driving seismic transient emission in flares. The implications of direct involvement by magnetic forces in seismic transient emission, if this could be confirmed, would be major, since magnetic fields are thought to hold the energy source of the flares themselves. The energy invested into acoustic transients is a small fraction of the total released by the flare, but requires a massive impulse many times that required to accelerate high-energy electrons into which the energy is initially thought to be invested. What does this say about a flare mechanism that sometimes does both? We discuss some of the outstanding diagnostic questions that confront the recognition of magnetic-field transients associated with Lorentz force transients based on resources HMI, Hinode, AIA and other facilities offer us. Title: Force-free Magnetic Fields and Electric Currents inferred from Coronal Loops and Stereoscopy Authors: Aschwanden, Markus J.; Boerner, P.; Schrijver, C. J.; Malanushenko, A. Bibcode: 2012decs.confE.105A Altcode: Force-free magnetic fields are considered to be a natural state of the low plasma-beta corona. There exist about a dozen of numerical nonlinear force-free field (NLFFF) computation codes that are able to caclulate a divergence-free and force-free solution of the magnetic field, by extrapolation from a lower boundary condition that is specified with 3D vector magnetograph data. However, significant differences in the solutions have been found among the different NLFFF codes, as well as in comparison with stereoscopically triangulated 3D coordinates of coronal loops, exhibiting field misalignment angles of 20-40 degrees. Each calculation of a NLFFF solution is computing-intensive and no code is fast enough to enable forward-fitting to observations. Here we derive an analytical approximation of NLFFF solutions that is accurate to second order and can efficiently be used for forward-fitting to coronal loops. We demonstrate the accurcay of the NLFFF forward-fitting code by reproducing the Low and Lou (1990) analytical model withg an accuracy of <5 degres. Further, we show examples of fitted NLFFF solutions to STEREO observations of coronal loops. Future NLFFF fits are expected based on line-of-sight magnetograms and automated loop tracings only, without requiring vector field and STEREO data. Title: Non-Linear Force-Free Modeling of Solar Corona With The Aid of Coronal Loops Authors: Malanushenko, A.; DeRosa, M.; Schrijver, C.; Wheatland, M. S.; Gilchrist, S. Bibcode: 2012decs.confE.113M Altcode: Accurate models of the coronal magnetic field are vital for understanding and predicting solar activity and are therefore of the greatest interest for solar physics. As no reliable measurements of the coronal magnetic field exists at present, the problem of constructing field models is typically viewed as a boundary value problem. The construction of realistic field models requires knowledge of the full vector of magnetic field at the boundaries of the model domain; vector magnetograms are, however, measured in the non force-free photosphere and their horizontal components are subject to large uncertainties. Even if an uncertainty-free vector magnetogram at the top layer of the chromosphere was known, the problem remains an extremely challenging non-linear problem. There are various methods for pre-processing vector magnetograms and using them to construct models of the coronal field. The success of these models is often judged based on how close its field lines correspond to the observed coronal loops, which are believed to follow lines of the coronal magnetic field. At present, the correspondence between coronal loops and magnetic field lines of many models based on the vector magnetograms is far from perfect (DeRosa et. al., 2009). The estimates of free energy in the field as well as distribution of the magnetic currents through the volume could be dramatically different for different models used (Schrijver et. al., 2008). This testifies to the need of a completely new approach to this problem. We present such an approach and demonstrate its results based on AIA and HMI data. We have developed a way to use coronal loops as a constraint for magnetic modelling; the field is therefore constructed to match coronal loops. We found that when tested on known magnetic fields the new method is able to reproduce overall shape of the field lines, large-scale spatial distribution of the electric currents and measure up to 60% of the free energy stored in the field. This was achieved with as little as line-of-sight magnetogram and less than hundred of synthetic "loops", that is, lines of magnetic fields projected onto a plane of the sky. We found that line-of-sight HMI magnetograms and spatial resolution of the AIA instrument combined with the amount of filters available are more than sufficient for obtaining such data. We briefly describe this new method and demonstrate reconstructions of the coronal magnetic field obtained using AIA and HMI data. We evaluate how well it reproduces coronal features and how much energy and helicity estimates fluctuate with time for a stable non-flaring active region, thus establishing the reliability of the new method. Title: Non-Linear Force-Free Modeling With The Aid of Coronal Observations Authors: Malanushenko, A. V.; DeRosa, M. L.; Schrijver, C. J.; Gilchrist, S. A.; Wheatland, M. S. Bibcode: 2011AGUFMSH43B1956M Altcode: Currently many models of coronal magnetic field rely on vector magnetograms and other kinds of information drawn from the photosphere. Magnetic fields in the corona, however, manifest themselves in the shapes of coronal loops, providing a constraint that at the present stage receives little use due to mathematical complications of incorporating such input into the numeric models. Projection effects and the limited number of usable loops further complicate their use. We present a possible way to account for coronal loops in the models of magnetic field. We first fit the observed loops with lines of constant-alpha fields and thus approximate three-dimensional distribution of currents in the corona along a sparse set of trajectories. We then apply a Grad-Rubin-like averaging technique to obtain a volume-filling non-linear force-free model of magnetic field, modified from the method presented in Wheatland & Regnier (2009). We present thorough tests of this technique on several known magnetic fields that were previously used for comparing different extrapolation techniques (Schrijver et. al., 2006; Metcalf et. al., 2008; Schrijver et. al., 2008; DeRosa et. al., 2009), as well as on solar data and compare the results with those obtained by the currently developed methods that rely completely on the photospheric data. Title: Direct Measurements of Magnetic Twist in the Solar Corona Authors: Malanushenko, A.; Yusuf, M. H.; Longcope, D. W. Bibcode: 2011ApJ...736...97M Altcode: 2012arXiv1202.5421M In the present work, we study the evolution of magnetic helicity in the solar corona. We compare the rate of change of a quantity related to the magnetic helicity in the corona to the flux of magnetic helicity through the photosphere and find that the two rates are similar. This gives observational evidence that helicity flux across the photosphere is indeed what drives helicity changes in the solar corona during emergence. For the purposes of estimating coronal helicity, we neither assume a strictly linear force-free field nor attempt to construct a nonlinear force-free field. For each coronal loop evident in extreme ultraviolet, we find a best-matching line of a linear force-free field and allow the twist parameter α to be different for each line. This method was introduced and its applicability discussed in Malanushenko et al. The object of this study is emerging and rapidly rotating AR 9004 over about 80 hr. As a proxy for coronal helicity, we use the quantity langα i Li /2rang averaged over many reconstructed lines of magnetic field. We argue that it is approximately proportional to the "flux-normalized" helicity H/Φ2, where H is the helicity and Φ is the total enclosed magnetic flux of the active region. The time rate of change of such a quantity in the corona is found to be about 0.021 rad hr-1, which is comparable with the estimates for the same region obtained using other methods, which estimated the flux of normalized helicity to be about 0.016 rad hr-1. Title: Computing Magnetic Energy From Aia Images And Hmi Line-of-sight Magnetograms Authors: Longcope, Dana; Malanushenko, A.; Tarr, L. Bibcode: 2011SPD....42.2118L Altcode: 2011BAAS..43S.2118L The state of the art for computing the magnetic energy in an active region's corona is to extrapolate a non-linear force-free field from vector magnetic field data. This method infers coronal properties from photospheric data without direct use of any coronal information. We present here an alternative which uses the shapes of loops visible in EUV or soft X-ray images to infer coronal currents. The method of Malanushenko et al. (2009) is used to infer magnetic field strength along each coronal loop. This sparse sampling of magnetic information is used in a Monte Carlo integral to compute the total magnetic energy. We also present a method for computing the free energy (the difference between the energy of the actual field and the corresponding potential field) directly as a single Monte Carlo integral. Both integrals are estimates with known statistical uncertainties which are reasonably small for samples as small as 25 loops. We demonstrate the method using a test field and then apply it to observations of an active region. Title: Simulating Coronal Emission in Six AIA Channels Using Quasi-Static Atmosphere Models and Non-Linear Magnetic Field Models Authors: Malanushenko, Anna; Schrijver, C.; DeRosa, M.; Aschwanden, M.; Wheatland, M. S.; van Ballegooijen, A. A. Bibcode: 2011SPD....42.2116M Altcode: 2011BAAS..43S.2116M We present the results of simulations of the EUV coronal emission in AIA channels. We use a non-linear force-free model of magnetic field constructed in such a way that its field lines resemble the observed coronal loops in EUV. We then solve one-dimensional quasi-steady atmosphere model along the magnetic field lines (Schrijver & Ballegooijen, 2005). Using coronal abundances from CHIANTI and AIA response functions we then simulate the emission that would be observed in AIA EUV channels. The resulting intensities are compared against the real observations in a manner similar to that in Aschwanden et. al., 2011. The study is similar to those by Lindquist et. al., 2008, with a few important differences. We use a model of the coronal magnetic field that resembles the topology observed in EUV, we study EUV emission of cool loops (rather than SXR) and we make use of high resolution and cadence AIA and HMI data. Title: Quantifying Separator Reconnection Between Emerging and Existing Active Regions Authors: Malanushenko, Anna; Longcope, D. W.; McKenzie, D. E.; Yusuf, M. H. Bibcode: 2010AAS...21640507M Altcode: 2010BAAS...41..890M When one active region emerges close to an older active region, coronal loops connecting the two regions are often observed in extreme ultraviolet (EUV). This signifies the occurrence of magnetic reconnection, an important mechanism in other contexts, such as solar flares and coronal mass ejections. We measure the rate of the magnetic reconnection by identifying each coronal loop observed in EUV that connects the existing and the emerging active regions. For each loop we estimate amount of magnetic flux it carries by measuring its apparent width in EUV and the magnetic field strength in the same location using (non)-linear force-free field reconstruction (Malanushenko et. al., 2009). We find that the amount of reconnected flux apparent on EUV is smaller than the flux through the separator surface in the point charge magnetic model (Longcope, 2005). This discrepancy provides a means to estimate the fraction of reconnecting loops that would appear in the EUV bandpass. We measure the delay time between the noticeable beginning of the emergence and the reconnection apparent in EUV. We apply this analysis to five emergence events. This work expands and improves the method described by Longcope et. al. (2005). Title: Twist in coronal magnetic fields Authors: Malanushenko, Anna Viktorovna Bibcode: 2010PhDT........68M Altcode: Twist of magnetic field is believed to play important role in driving instabilities that result in eruptive events on the Sun. This thesis provides different methods to measure twist in the solar corona. First, given a model of coronal field, twist of a magnetic domain (i.e., a volume that contains all field lines connecting two regions of interest in the photosphere) is well studied for cases when the domain is a thin cylinder. For cases when such approximation is inapplicable a generalization of twist can be derived from a quantity called additive self-helicity. I develop explicit numerical methods to compute generalized twist. I also demonstrate that such a quantity sets a threshold on kink instability like the traditional twist does for thin cylinders. In a more realistic scenario, coronal magnetic field is not known and so neither is its helicity. There are two principal methods to overcome this problem. The first is to integrate helicity flux across the photosphere (as helicity is believed to be approximately conserved in the corona) using magnetic field on Sun's surface. There is little published evidence as yet that coronal helicity indeed corresponds to its integrated photospheric flux. The second is to extrapolate the coronal magnetic field using surface measurements as boundary conditions and use this extrapolation for helicity computation; for fields with complicated structure such extrapolations are extremely challenging and suffer from major drawbacks. I develop a method to estimate twist of coronal fields without attempting complicated extrapolations or studying helicity flux. The method builds a simple uniformly-twisted magnetic field and adjusts its properties until there is one line in this field that matches one coronal loop; this is repeated for all evident coronal loops resulting in twist measurements for each individual loop. I use this method to demonstrate that the rate of change of twist in the solar corona is indeed approximately equal to the one derived from photospheric helicity flux. The results of this dissertation are useful for better understanding of magnetic topology in general. They are also extremely promising for extrapolating coronal magnetic fields. Measurements of coronal twist might aid in predicting magnetic instabilities. Title: Reconstructing the Local Twist of Coronal Magnetic Fields and the Three-Dimensional Shape of the Field Lines from Coronal Loops in Extreme-Ultraviolet and X-Ray Images Authors: Malanushenko, A.; Longcope, D. W.; McKenzie, D. E. Bibcode: 2009ApJ...707.1044M Altcode: 2009arXiv0909.5141M Nonlinear force-free fields are the most general case of force-free fields, but the hardest to model as well. There are numerous methods of computing such fields by extrapolating vector magnetograms from the photosphere, but very few attempts have so far made quantitative use of coronal morphology. We present a method to make such quantitative use of X-ray and EUV images of coronal loops. Each individual loop is fit to a field line of a linear force-free field, allowing the estimation of the field line's twist, three-dimensional geometry, and the field strength along it. We assess the validity of such a reconstruction since the actual corona is probably not a linear force-free field, and that the superposition of linear force-free fields is generally not itself a force-free field. To do so, we perform a series of tests on nonlinear force-free fields, described in Low & Lou. For model loops we project field lines onto the photosphere. We compare several results of the method with the original field, in particular the three-dimensional loop shapes, local twist (coronal α), distribution of twist in the model photosphere, and strength of the magnetic field. We find that (1) for these trial fields, the method reconstructs twist with a mean absolute deviation of at most 15% of the range of photospheric twist, (2) heights of the loops are reconstructed with a mean absolute deviation of at most 5% of the range of trial heights, and (3) the magnitude of non-potential contribution to a photospheric field is reconstructed with a mean absolute deviation of at most 10% of the maximal value. Title: Measuring Coronal Magnetic Twist Injected by Photospheric Rotation Authors: Malanushenko, A.; Yusuf, M.; Longcope, D. W. Bibcode: 2009AGUFMSH23B1537M Altcode: Measuring the twist of the coronal magnetic field is important for understanding and predicting solar flares. The studies of instabilities in the past decades suggest a relation between solar flares and instabilities, such as the external kink mode, driven by excessive twist. We study the buildup of twist in an emerging and rapidly rotating active region (AR 9002) using the technique developed by Malanushenko et al. (2009). This uses EUV coronal images, from TRACE, and line-of-sight magnetograms, from MDI, to infer properties of the coronal magnetic field, including its local twist parameter alpha. We find that the twist of AR 9002 does not change with time, while twist of emerging AR 9004 starts left handed and becomes, after 80 hours, right handed. We compare the change rate of twist for AR 9004 to the predicted rate given the simple model of braiding and spinning flux tube and demonstrate the general agreement of the two. We also characterize the coronal twist of the flux interconnecting the two regions which is produced through reconnection. This work was supported by NASA and NSF. Title: Additive Self-helicity as a Kink Mode Threshold Authors: Malanushenko, A.; Longcope, D. W.; Fan, Y.; Gibson, S. E. Bibcode: 2009ApJ...702..580M Altcode: 2009arXiv0909.4959M In this paper, we propose that additive self-helicity, introduced by Longcope and Malanushenko, plays a role in the kink instability for complex equilibria, similar to twist helicity for thin flux tubes. We support this hypothesis by a calculation of additive self-helicity of a twisted flux tube from the simulation of Fan and Gibson. As more twist gets introduced, the additive self-helicity increases, and the kink instability of the tube coincides with the drop of additive self-helicity, after the latter reaches the value of HA /Φ2 ≈ 1.5 (where Φ is the flux of the tube and HA is the additive self-helicity). We compare the additive self-helicity to twist for a thin subportion of the tube to illustrate that HA /Φ2 is equal to the twist number, studied by Berger and Field, when the thin flux tube approximation is applicable. We suggest that the quantity HA /Φ2 could be treated as a generalization of a twist number, when the thin flux tube approximation is not applicable. A threshold on a generalized twist number might prove extremely useful studying complex equilibria, just as the twist number itself has proven useful studying idealized thin flux tubes. We explicitly describe a numerical method for calculating additive self-helicity, which includes an algorithm for identifying a domain occupied by a flux bundle and a method of calculating potential magnetic field confined to this domain. We also describe a numerical method to calculate twist of a thin flux tube, using a frame parallelly transported along the axis of the tube. Title: Inferring Local Twist of the Coronal Magnetic Field from Coronal Loops in EUV and X-ray Images Authors: Malanushenko, Anna; Longcope, D. W.; McKenzie, D. E. Bibcode: 2009SPD....40.2902M Altcode: Non-linear force-free fields are the most general case of force-free fields, but the hardest to model as well. There are numerous methods of computing such fields by extrapolating vector magnetograms from the photosphere, but very few attempts have so far made quantitative use of coronal morphology. We present an improved method which infers properties of the force-free field from X-Ray and EUV images of active region coronal loops. Each loop evident in an image is fit to field lines from constant-alpha fields. Our algorithm thereby estimates the three-dimensional geometry of each loop as well its local twist (alpha) and the magnetic field strength over its length. We assess the performance of this method by applying it to known examples of 3D non-linear force free fields. We demonstrate that at least some features of the local twist distribution could be reconstructed using this method. Title: Modeling the Evolving Magnetic Field in a Coronal Sigmoid Authors: McKenzie, David Eugene; Malanushenko, A.; Longcope, D. Bibcode: 2009SPD....40.1203M Altcode: The importance of coronal sigmoids as progenitors of eruptions and mass ejections is well established. However, the storage of magnetic energy prior to a sigmoid's eruption is difficult to quantify. While the non-potentiality of the coronal force-free fields is clearly responsible for the free energy, models of the field are difficult to verify. We utilize a method, developed at Montana State University and described at this meeting by A. Malanushenko, to model the force-free field within a coronal sigmoid observed by TRACE and Hinode/XRT. By modeling the twist in the sigmoid's field over the span of a few days leading up to its eruption, it is hoped that such a model can yield insight to the buildup of energy. This work is supported by NASA contract NNX07AI01G, and by SAO contract SV7-77003. Title: Defining and Calculating Self-Helicity in Coronal Magnetic Fields Authors: Longcope, D. W.; Malanushenko, A. Bibcode: 2008ApJ...674.1130L Altcode: We introduce two different generalizations of relative helicity which may be applied to a portion of the coronal volume. Such a quantity is generally referred to as the self-helicity of the field occupying the subvolume. Each definition is a natural application of the traditional relative helicity but relative to a different reference field. One of the generalizations, which we term additive self-helicity, can be considered a generalization of twist helicity to volumes which are neither closed nor thin. It shares with twist the property of being identically zero for any portion of a potential magnetic field. The other helicity, unconfined self-helicity, is independent of the shape of the volume occupied by the field portion and is therefore akin to the sum of twist and writhe helicity. We demonstrate how each kind of self-helicity may be evaluated in practice. The set of additive self-helicities may be used as a constraint in the minimization of magnetic energy to produce a piecewise constant-α equilibrium. This class of fields falls into a hierarchy, along with the flux-constrained equilibria and potential fields, of fields with monotonically decreasing magnetic energies. Piecewise constant-α fields generally have fewer unphysical properties than genuinely constant-α fields, whose twist α is uniform throughout the entire corona. Title: Quantifying The Self-helicity Of A Flux Tubes Authors: Malanushenko, Anna; Longcope, D. Bibcode: 2007AAS...210.9110M Altcode: 2007BAAS...39..205M Magnetic helicity has proven to be a powerful tool for understanding energetics of the solar corona. As it is usually defined, relative helicity is an integral over the entire coronal volume. In this work we consider two different generalizations by which relative helicity of a portion of the entire coronal volume may be calculated. Such a quantity is generally called the self helicity of the sub-volume. Each definition is a natural application of the traditional helicity formula but relative to different fields. One of the generalizations, which we term "additive self-helicity", has particularly desirable properties, such as being identically zero for any portion of a potential magnetic field. During a flare it is believed that the total helicity of the volume is conserved, but as reconnection transfers flux between domains, this will change the self-helicity of those. We demonstrate how "additive self-helicity" may be evaluated in practice to find the self-helicities for flux systems, or domains, composed of all field lines connecting a designated pair of photospheric source regions. It is then possible to quantify the transfer of self-helicity which would occur when reconnection transfers flux between flux systems. Title: Quantifying The Relationship Between Reconnection Rate And Energy Release In A Survey Of Coronal Bright Points Authors: Malanushenko, Anna V.; Longcope, D.; Aver, E.; Kankelborg, C. Bibcode: 2006SPD....37.1001M Altcode: 2006BAAS...38Q.237M This is an observational study of coronal bright points aimed at quantifying the relationship between reconnection rate and dissipated power. We assemble surveys of 733 bright from archival SOHO data. Bright points are found in two channels of EIT (EUV Imaging Telescope) data. We match these features to magnetic bipoles found in photospheric magnetic field observations of MDI. From the MDI magnetograms we extract measurements of each quantity relevant to simple three-dimensional reconnection model including the relative velocities of the magnetic poles. The study reveals temporal and spatial properties of X-ray bright points and compares them to the simple models of spatial distribution over the disk. The temporal evolution of the poles is used to test the hypothesis that coronal heating is due to magnetic reconnection and furthermore to quantify the relationship between reconnection rate and heating power.This work was supported by NASA under grant NAG5-10489. Title: The GONG Farside Project Authors: Leibacher, J. W.; Braun, D.; González Hernández, I.; Goodrich, J.; Kholikov, S.; Lindsey, C.; Malanushenko, A.; Scherrer, P. Bibcode: 2005AGUSMSP11B..14L Altcode: The GONG program is currently providing near-real-time helioseismic images of the farside of the Sun. The continuous stream of low resolution images, obtained from the 6 earth based GONG stations, are merged into a single data series that are the input to the farside pipeline. In order to validate the farside images, it is crucial to compare the results obtained from different instruments. We show comparisons between the farside images provided by the MDI instrument and the GONG ones. New aditions to the pipeline will allow us to create full-hemisphere farside images, examples of the latest are shown in this poster. Our efforts are now concentrated in calibrating the farside signal so it became a reliable solar activity forecasting tool. We are also testing single-skip acoustic power holography at 5-7 mHz as a prospective means of reinforcing the signatures of active regions crossing the the east and west limb and monitoring acoustic emission in the neighborhoods of Sun's the poles. This work utilizes data obtained by the Global Oscillation Network Group (GONG) Program, managed by the National Solar Observatory, which is operated by AURA, Inc. under a cooperative agreement with the National Science Foundation. The data were acquired by instruments operated by the Big Bear Solar Observatory, High Altitude Observatory, Learmonth Solar Observatory, Udaipur Solar Observatory, Instituto de Astrofisico de Canarias, and Cerro Tololo Interamerican Observatory, as well as the Michaelson Doppler Imager on SoHO, a mission of international cooperation between ESA and NASA. This work has been supported by the NASA Living with a Star - Targeted Research and Technology program. Title: Remote distributed pipeline processing of GONG helioseismic data: experience and lessons learned Authors: Goodrich, Jean N.; Kholikov, Shukur; Lindsey, Charles; Malanushenko, Anna; Shroff, Chirag; Toner, Clifford Bibcode: 2004SPIE.5493..538G Altcode: The Global Oscillation Network Group (GONG) helioseismic network can create images of the farside of the Sun which frequently show the presence of large active regions that would be otherwise invisible. This ability to "see" through the sun is of potential benefit to the prediction of solar influences on the Earth, provided that the data can be obtained and reduced in a timely fashion. Thus, GONG is developing a system to A) perform initial data analysis steps at six geographically distributed sites, B) transmit the reduced data to a home station, C) perform the final steps in the analysis, and D) distribute the science products to space weather forecasters. The essential requirements are that the system operate automatically around the clock with little human intervention, and that the science products be available no more than 48 hours after the observations are obtained. We will discuss the design, implementation, testing, and current status of the system. Title: Acoustic Holographic Studies of Solar Active Regions Authors: Malanushenko, A.; Braun, D.; Kholikov, S.; Leibacher, J.; Lindsey, C. Bibcode: 2004IAUS..223..283M Altcode: 2005IAUS..223..283M We present results of a study of the morphology and evolution of active regions using solar acoustic holography. These include acoustic signatures of large far-side active regions and their relationship to near-side activity indices a half rotation before and after the farside image, and the direct comparison of near-side acoustic signatures with the standard activity indicators, not only in their own right but also to calibrate the farside acoustic signature.