Author name code: deforest ADS astronomy entries on 2022-09-14 author:"DeForest, Craig" ------------------------------------------------------------------------ Title: Defining the Middle Corona Authors: West, Matthew J.; Seaton, Daniel B.; Wexler, David B.; Raymond, John C.; Del Zanna, Giulio; Rivera, Yeimy J.; Kobelski, Adam R.; DeForest, Craig; Golub, Leon; Caspi, Amir; Gilly, Chris R.; Kooi, Jason E.; Alterman, Benjamin L.; Alzate, Nathalia; Banerjee, Dipankar; Berghmans, David; Chen, Bin; Chitta, Lakshmi Pradeep; Downs, Cooper; Giordano, Silvio; Higginson, Aleida; Howard, Russel A.; Mason, Emily; Mason, James P.; Meyer, Karen A.; Nykyri, Katariina; Rachmeler, Laurel; Reardon, Kevin P.; Reeves, Katharine K.; Savage, Sabrina; Thompson, Barbara J.; Van Kooten, Samuel J.; Viall, Nicholeen M.; Vourlidas, Angelos Bibcode: 2022arXiv220804485W Altcode: The middle corona, the region roughly spanning heliocentric altitudes from $1.5$ to $6\,R_\odot$, encompasses almost all of the influential physical transitions and processes that govern the behavior of coronal outflow into the heliosphere. Eruptions that could disrupt the near-Earth environment propagate through it. Importantly, it modulates inflow from above that can drive dynamic changes at lower heights in the inner corona. Consequently, this region is essential for comprehensively connecting the corona to the heliosphere and for developing corresponding global models. Nonetheless, because it is challenging to observe, the middle corona has been poorly studied by major solar remote sensing missions and instruments, extending back to the Solar and Heliospheric Observatory (SoHO) era. Thanks to recent advances in instrumentation, observational processing techniques, and a realization of the importance of the region, interest in the middle corona has increased. Although the region cannot be intrinsically separated from other regions of the solar atmosphere, there has emerged a need to define the region in terms of its location and extension in the solar atmosphere, its composition, the physical transitions it covers, and the underlying physics believed to be encapsulated by the region. This paper aims to define the middle corona and give an overview of the processes that occur there. Title: Square Root Compression and Noise Effects in Digitally Transformed Images Authors: DeForest, Craig E.; Lowder, Chris; Seaton, Daniel B.; West, Matthew J. Bibcode: 2022ApJ...934..179D Altcode: 2022arXiv220705601D We report on a particular example of noise and data representation interacting to introduce systematic error into scientific measurements. Many instruments collect integer digitized values and apply nonlinear coding, in particular square root coding, to compress the data for transfer or downlink; this can introduce surprising systematic errors when they are decoded for analysis. Square root coding and subsequent decoding typically introduces a variable ±1 count value-dependent systematic bias in the data after reconstitution. This is significant when large numbers of measurements (e.g., image pixels) are averaged together. Using direct modeling of the probability distribution of particular coded values in the presence of instrument noise, one may apply Bayes' theorem to construct a decoding table that reduces this error source to a very small fraction of a digitizer step; in our example, systematic error from square root coding is reduced by a factor of 20 from 0.23 to 0.012 count rms. The method is suitable both for new experiments such as the upcoming PUNCH mission, and also for post facto application to existing data sets-even if the instrument noise properties are only loosely known. Further, the method does not depend on the specifics of the coding formula, and may be applied to other forms of nonlinear coding or representation of data values. Title: Tracing the Drivers of Slow Solar Wind in the Middle Corona Authors: Chitta, Lakshmi Pradeep; DeForest, Craig; Downs, Cooper; Seaton, Daniel; Higginson, Aleida Bibcode: 2022cosp...44.1328C Altcode: Compared to the so-called fast solar wind that originates from polar coronal holes during the solar minimum, low-latitude wind streams generally have lower speeds ($\le$ 500 km/s). These slow solar wind streams closer to the ecliptic plane are characterised by their high spatial structuring, temporal variability, and coronal compositions. The magnetic driver responsible for the origin of this slow solar wind and its characteristics, however, is a subject of active debate. Using coronal observations from the 2018 off-pointing campaign of the GOES Solar Ultraviolet Imager (SUVI) as well as images from SOHO/LASCO, we found signatures of solar wind streams driven by magnetic reconnection in the highly structured middle corona. In particular, elongated coronal loops in the middle corona over a coronal-hole-active-region complex are observed to reconnect and retract while in the process, some plasma is propelled away from the Sun as streams or blobs. Using STEREO observations we found that similar streams forming over the same complex escape into the heliosphere. In this talk, we will present these new results and discuss them in the context of models of slow solar wind sources and drivers. our findings emphasise the key necessity of having routine extreme ultraviolet observations of the middle coronal processes from ecliptic and polar vantage points, along with extended coronal diagnostics to develop better understanding of the heliospheric impact of Sun's activity. 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: Quasi-periodic Energy Release and Jets at the Base of Solar Coronal Plumes Authors: Kumar, Pankaj; Karpen, Judith T.; Uritsky, Vadim M.; Deforest, Craig E.; Raouafi, Nour E.; Richard DeVore, C. Bibcode: 2022ApJ...933...21K Altcode: 2022arXiv220413871K Coronal plumes are long, ray-like, open structures that have been considered as possible sources of the solar wind. Their origin in the largely unipolar coronal holes has long been a mystery. Earlier spectroscopic and imaging observations revealed blueshifted plasma and propagating disturbances (PDs) in plumes that are widely interpreted in terms of flows and/or propagating slow-mode waves, but these interpretations (flows versus waves) remain under debate. Recently we discovered an important clue about plume internal structure: dynamic filamentary features called plumelets, which account for most of the plume emission. Here we present high-resolution observations from the Solar Dynamics Observatory/Atmospheric Imaging Assembly and the Interface Region Imaging Spectrograph that revealed numerous, quasi-periodic, tiny jets (so-called jetlets) associated with transient brightening, flows, and plasma heating at the chromospheric footpoints of the plumelets. By analogy to larger coronal jets, these jetlets are most likely produced within the plume base by magnetic reconnection between closed and open flux at stressed 3D null points. The jetlet-associated brightenings are in phase with plumelet-associated PDs, and vary with a period of ~3-5 minutes, which is remarkably consistent with the photospheric/chromospheric p-mode oscillation. This reconnection at the open-closed boundary in the chromosphere/transition region is likely modulated or driven by local manifestations of the global p-mode waves. The jetlets extend upward to become plumelets, contribute mass to the solar wind, and may be sources of the switchbacks recently detected by the Parker Solar Probe. Title: Remote Sensing of Turbulence and Solar Wind Structure with the PUNCH mission Authors: DeForest, Craig; Gibson, Sarah; Matthaeus, William; Viall, Nicholeen Bibcode: 2022cosp...44.1212D Altcode: The Polarimeter to UNify the Corona and Heliosphere is a mission to observe the corona and the inner heliosphere as a unified system. PUNCH will produce continuous images of the solar wind and corona between 1.5° and 45° from the Sun, over a two year prime science mission scheduled to start in early 2025. PUNCH uses visible sunlight scattered by free electrons in the corona, to track density structures in the corona and solar wind. We will describe PUNCH's unique 3D imaging capability, mission structure, and anticipated results measuring the development of large-scale turbulence, and the large- and meso-scale structure of the solar wind itself. Title: Bayesian analysis of square-rooted values Authors: DeForest, C. E.; Lowder, C.; Seaton, D. B.; West, M. J. Bibcode: 2022zndo...6672640D Altcode: This is a pair of Jupyter notebooks developing a second-order-approximation square root decoder, using a Bayesian approach to interpreting detector values. The square root decoder improves residual error from ~0.24DN RMS to ~0.013DN RMS in a typical application. The Jupyter format allows reproduction and numerical experiment for other applications. One notebook shows the method's derivation and verification; the other shows application to a particular data set. 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: Three-polarizer Treatment of Linear Polarization in Coronagraphs and Heliospheric Imagers Authors: DeForest, Craig E.; Seaton, Daniel B.; West, Matthew J. Bibcode: 2022ApJ...927...98D Altcode: 2021arXiv211211504D Linearly polarized light has been used to view the solar corona for over 150 years. While the familiar Stokes representation for polarimetry is complete, it is best matched to a laboratory setting and therefore is not the most convenient representation either for coronal instrument design or for coronal data analysis. Over the last 100 years of development of coronagraphs and heliospheric imagers, various representations have been used for both direct measurement and analysis. These systems include famous representations such as the (B, pB) system, which is analogous to the Stokes system in solar observing coordinates, and also internal representations such as in-instrument Stokes parameters with fixed or variable "vertical" direction, and brightness values through a particular polarizing optic or set thereof. Many polarimetric instruments currently use a symmetric three-polarizer measurement and representation system (which we refer to as "(M, Z, P)") to derive the (B, pB) or Stokes parameters. We present a symmetric derivation of (B, pB) and Stokes parameters from (M, Z, P), analyze the noise properties of (M, Z, P) in the context of instrument design, develop (M, Z, P) as a useful intermediate system for data analysis including background subtraction, and draw a helpful analogy between linear polarimetric systems and the large existing body of work on photometric colorimetry. Title: A Strategy for a Coherent and Comprehensive Basis for Understanding the Middle Corona Authors: West, M. J.; Seaton, D. B.; Alzate, N.; Caspi, A.; DeForest, C. E.; Gilly, C. R.; Golub, L.; Higginson, A. K.; Kooi, J. E.; Mason, J. P.; Rachmeler, L. A.; Reeves, K. K.; Reardon, K.; Rivera, Y. J.; Savage, S.; Viall, N. M.; Wexler, D. B. Bibcode: 2022heli.conf.4060W Altcode: We describe a strategy for coherent and comprehensive observations needed to achieve a fundamental understanding of the middle solar corona. Title: Small Satellite Mission Concepts for Space Weather Research and as Pathfinders for Operations Authors: Caspi, Amir; Barthelemy, M.; Bussy-Virat, C. D.; Cohen, I. J.; DeForest, C. E.; Jackson, D. R.; Vourlidas, A.; Nieves-Chinchilla, T. Bibcode: 2022SpWea..2002554C Altcode: 2022arXiv220107426C Recent advances in miniaturization and commercial availability of critical satellite subsystems and detector technology have made small satellites (SmallSats, including CubeSats) an attractive, low-cost potential solution for space weather research and operational needs. Motivated by the first International Workshop on SmallSats for Space Weather Research and Forecasting, held in Washington, DC on 1-4 August 2017, we discuss the need for advanced space weather measurement capabilities, driven by analyses from the World Meteorological Organization (WMO), and how SmallSats can efficiently fill these measurement gaps. We present some current, recent missions and proposed/upcoming mission concepts using SmallSats that enhance space weather research and provide prototyping pathways for future operational applications; how they relate to the WMO requirements; and what challenges remain to be overcome to meet the WMO goals and operational needs in the future. With additional investment from cognizant funding agencies worldwide, SmallSats—including standalone missions and constellations—could significantly enhance space weather research and, eventually, operations, by reducing costs and enabling new measurements not feasible from traditional, large, monolithic missions. Title: Can solar coronal plumelets precondition switchback events in the wind? Authors: Uritsky, Vadim; DeForest, Craig; Karpen, Judith; DeVore, C. Richard; Kumar, Pankaj; Raouafi, Nour; Wyper, Peter Bibcode: 2021AGUFMSH24C..05U Altcode: Filamentary structures and motions in plume images have been known for many years (e.g., Raouafi & Stenborg (2014) and references therein). Recently, we have presented the first in-depth quantitative investigation of these structures, which we denoted plumelets (Uritsky et al., 2021). Using an extended set of high-resolution, high-cadence solar coronal images covering 40 hr of nearly continuous observations of a typical solar coronal plume by SDO/AIA on 2016 July 23, we have investigated the highly dynamic nature of the plumelets. The figure below (courtesy NASA/SDO) provides an example of processing of a high-resolution SDO/AIA image to reveal distinct plumelets within the studied plume. Our analysis has demonstrated that the impulsive behavior of the plumelets may dominate the large-scale behavior of the host plume. The plumelets support persistent longitudinal fluctuations whose typical period (35 minutes) is consistent with the peak-power period of the solar p-modes, and the radial propagation speed (190240 km/s) is in agreement with the characteristic speed of plasma outflows in a typical coronal hole jet. Elsewhere (Kumar et al., 2021), we present evidence for direct causal connection between the plumelets, jetlets, and localized reconnection activity observed at the plume base. In this talk, we focus on the stability and spatio-temporal correlation pattern of the velocity field in a system of multiple coronal plumelets. Our analysis reveals significant transient velocity shears at the interface boundaries of adjacent plumelets. We argue that these shears could lead to a localized onset of Kelvin Helmholtz instability in the downstream plume plasma, which could introduce topological irregularities in the frozen-in magnetic field and facilitate the formation of switchbacks and other small-scale structures in the magnetically connected solar wind. 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: Polarimeter to UNify the Corona and Heliosphere: Mission status, activity, and science planning Authors: DeForest, Craig; Gibson, Sarah; Killough, Ronnie; Case, Traci; Beasley, Matthew; Laurent, Glenn; Colaninno, Robin Bibcode: 2021AGUFMSH35C2090D Altcode: The Polarimeter to UNify the Corona and Heliosphere (PUNCH) is an in-development mission, now in a combined Phase C/D in the NASA mission lifecycle, to image the outer solar corona and inner heliosphere as a unified system. The flight assets comprise four spacecraft to be launched to 6am/6pm Sun-synchronous Low-Earth Orbit; one spacecraft carries a Narrow Field Imager (NFI) coronagraph, and three carry copies of a Wide Field Imager (WFI) heliospheric imager. These prime instruments are specifically designed to work together as a seamless "virtual instrument" with a 90° FOV, centered on the Sun. PUNCH will produce polarized (pB) and unpolarized (B) images of the young solar wind as it forms and departs the Sun, allowing 3D analysis of solar wind and CME structure and trajectory. Aa student-contributed instrument, STEAM, comprises two solid-state X-ray spectrometers to study coronal heating and flare physics. PUNCH has an open data policy and all data products will be made available to everyone at the same time as the mission team. PUNCH is working to a launch readiness date of 3-Oct-2023. The PUNCH science team comprises PI Craig DeForest, PS Sarah Gibson, and project Co-Investigators and Associate Investigators. Organized into six working groups, we are actively preparing for the 2-year prime mission starting 90 days after launch. Science team meetings are open to all, and are announced in the usual venues and the PUNCH web page (https://punch.space.swri.edu). Current preparations include forward modeling, derivation of predicted image characteristics from existing data, and development of a suite of analysis tools in the vigorous open-source Python/NumPy/SunPy millieu. The mission is complemented by the groundbreaking PUNCH Outreach Program (POP) centered around a theme of ancient and modern sunwatching, and concentrated in the American Southwest. POP is specifically designed to support national, as well as regional, educational and outreach efforts and to stimulate interest in science by engaging under-represented populations in the focus region and around the nation. We will present the current technical status of PUNCH, the primary science objectives and observing plan, current preparation activity and working group structure, and pathways to coordinate and/or get involved with the mission. Title: Translational Tomography with WISPR: Basis of Method and Current Progress Authors: Kenny, Megan; DeForest, Craig; West, Matthew; Liewer, Paulett Bibcode: 2021AGUFMSH42A..07K Altcode: We present first steps toward "translational tomography" of the solar corona, using images that WISPR has captured in recent perihelia. Our method relies on known perspective changes due to the rapid trajectory of PSP through the solar corona near perihelion. The method allows extraction of feature location and large-scale structure near the track of the spacecraft itself. To produce the inversions, we neglect local proper motions and model the apparent kinematics of a stationary solar wind feature, from WISPR's point of view. This family of analytic functions serves as a partial basis for the vector space of WISPR image sequences; a change-of-basis operation yields the initial tomogram. For initial analyses we confine ourselves to the ribbon of material whose length runs along the track of the spacecraft and whose width runs perpendicular to that track (locally horizontal). We present the basics of the method and initial test results from a pre-flight model and from three recent perihelion passes. Future work includes regularization of the basis vectors and improvement of the basic proof-of-concept inversions. The tool will grow in utility as the orbital distances decrease in future encounters. Title: The Multiview Observatory for Solar Terrestrial Science (MOST) Authors: Gopalswamy, Nat; Kucera, Therese; Leake, James; MacDowall, Robert; Wilson, Lynn; Kanekal, Shrikanth; Shih, Albert; Christe, Steven; Gong, Qian; Viall, Nicholeen; Tadikonda, Sivakumar; Fung, Shing; Yashiro, Seiji; Makela, Pertti; Golub, Leon; DeLuca, Edward; Reeves, Katharine; Seaton, Daniel; Savage, Sabrina; Winebarger, Amy; DeForest, Craig; Desai, Mihir; Bastian, Tim; Lazio, Joseph; Jensen, P. E., C. S. P., Elizabeth; Manchester, Ward; Wood, Brian; Kooi, Jason; Wexler, David; Bale, Stuart; Krucker, Sam; Hurlburt, Neal; DeRosa, Marc; Pevtsov, Alexei; Tripathy, Sushanta; Jain, Kiran; Gosain, Sanjay; Petrie, Gordon; Kholikov, Shukirjon; Zhao, Junwei; Scherrer, Philip; Woods, Thomas; Chamberlin, Philip; Kenny, Megan Bibcode: 2021AGUFMSH12A..07G Altcode: The Multiview Observatory for Solar Terrestrial Science (MOST) is a comprehensive mission concept targeting the magnetic coupling between the solar interior and the heliosphere. The wide-ranging imagery and time series data from MOST will help understand the solar drivers and the heliospheric responses as a system, discerning and tracking 3D magnetic field structures, both transient and quiescent in the inner heliosphere. MOST will have seven remote-sensing and three in-situ instruments: (1) Magnetic and Doppler Imager (MaDI) to investigate surface and subsurface magnetism by exploiting the combination of helioseismic and magnetic-field measurements in the photosphere; (2) Inner Coronal Imager in EUV (ICIE) to study large-scale structures such as active regions, coronal holes and eruptive structures by capturing the magnetic connection between the photosphere and the corona to about 3 solar radii; (3) Hard X-ray Imager (HXI) to image the non-thermal flare structure; (4) White-light Coronagraph (WCOR) to seamlessly study transient and quiescent large-scale coronal structures extending from the ICIE field of view (FOV); (5) Faraday Effect Tracker of Coronal and Heliospheric structures (FETCH), a novel radio package to determine the magnetic field structure and plasma column density, and their evolution within 0.5 au; (6) Heliospheric Imager with Polarization (HIP) to track solar features beyond the WCOR FOV, study their impact on Earth, and provide important context for FETCH; (7) Radio and Plasma Wave instrument (M/WAVES) to study electron beams and shocks propagating into the heliosphere via passive radio emission; (8) Solar High-energy Ion Velocity Analyzer (SHIVA) to determine spectra of electrons, and ions from H to Fe at multiple spatial locations and use energetic particles as tracers of magnetic connectivity; (9) Solar Wind Magnetometer (MAG) to characterize magnetic structures at 1 au; (10) Solar Wind Plasma Instrument (SWPI) to characterize plasma structures at 1 au. MOST will have two large spacecraft with identical payloads deployed at L4 and L5 and two smaller spacecraft ahead of L4 and behind L5 to carry additional FETCH elements. MOST will build upon SOHO and STEREO achievements to expand the multiview observational approach into the first half of the 21st Century. Title: Direct Evidence for the Dynamic Chromospheric Origin of Solar Coronal Plumes Authors: Kumar, Pankaj; Karpen, Judy; Uritsky, Vadim; DeForest, Craig; Raouafi, Nour; DeVore, C. Richard Bibcode: 2021AGUFMSH25F2145K Altcode: Coronal plumes are long ray-like open structures in coronal holes, and have been considered as possible sources for the fast solarwind. Their origin in the largely unipolar coronal holes has long been a mystery. Earlier spectroscopic and imaging observationshave revealed blue-shifted plasma and propagating disturbances (PDs) in plumes that are widely interpreted in terms of flowsand/or propagating slow-mode waves, but these interpretations (flows vs waves) are under debate. Recently we discovered an important clue about plume internal structure: dynamic filamentary features called plumelets, which account formost of the plume emission. Here we present high-resolution observations from SDO/AIA and IRIS that revealed numerous quasiperiodic tiny jets (so-called jetlets") associated with transient brightening and plasma heating at the chromospheric footpoints of the plumelets. By analogy to larger coronal jets, these jetlets are most likely produced within the plume base by magnetic reconnection between closed and open flux at a stressed 3D null point. The jetlet-associated brightenings are in phase with plumelet-associated PDs, and vary with a period of 3 to 5 minutes, which is remarkably consistent with the photospheric/chromospheric p-mode oscillation. This reconnection at the open-closed boundary in the chromosphere/transition region is likely modulated or driven by local manifestations of the global p-mode waves. We discuss how these quasiperiodic jetlets extend upward to become plumelets, contribute mass to the solar wind, and may be sources of switchbacks recently detected by the Parker Solar Probe. Title: SynCOM: Synthetic Corona Outflow Model for the Heliophysics community Authors: Moraes Filho, Valmir; Uritsky, Vadim; Thompson, Barbara; DeForest, Craig Bibcode: 2021AGUFMSH24C..06M Altcode: Numerous methods for measuring coronal flow velocities have been developed over the years. These measurements are central to our understanding of the origin of the solar wind and serving to upcoming missions that address this problem, such as the Polarimeter to Unify the Corona and Heliosphere (PUNCH) mission. However, many of the existing flow tracking methods provide qualitatively reasonable outcomes, their quantitative validation across the wide range of coronal altitudes remains a problem. The lack of precise knowledge about the targeted velocity field is the primary obstacle, making it impossible to compare algorithms attempting to estimate flow parameters for the same coronal structure. To address this problem, we are designing the Synthetic Corona Outflow Model (SynCOM) an empirical data-driven model of a dynamic solar corona based on previous high-resolution observations. The SynCOM model mimics the transient and quasi-periodical behavior present in the actual solar corona, such as the one observed by STEREO-A/COR 2. The SynCOM outputs exhibit a true-to-life radial decay of the polarized brightness and include stochastic components accounting for physical fluctuations of plasma outflows and instrumental noise. Since the model has a predefined distribution of flow velocity and an adjustable signal-to-noise ratio, it can be used for testing a variety of data analysis methods used to measure coronal flows. Adjusting SynCOM settings for specific coronal conditions and instrumental parameters enables a straightforward comparison of accuracy and performance of different data analysis methods and measurement techniques designed to quantify velocity and acceleration in the corona. In this work, we will present examples of the application of SynCOM for verifying observational requirements for detecting coronal flows beyond the range of altitudes covered by previously operated coronagraphs; and benchmarking popular flow tracking codes used by the coronal physics community, and cross-validating their outputs. Title: Tracing the Drivers of Slow Solar Wind in the Middle Corona Authors: Chitta, Lakshmi Pradeep; Seaton, Daniel; Downs, Cooper; DeForest, Craig; Higginson, Aleida Bibcode: 2021AGUFMSH24C..01C Altcode: Compared to the so-called fast solar wind that originates from polar coronal holes during the solar minimum, low-latitude wind streams generally have lower speeds ( 500 km/s). These slow solar wind streams closer to the ecliptic plane are characterized by their high spatial structuring, temporal variability, and coronal compositions. The magnetic driver responsible for the origin of this slow solar wind and its characteristics, however, is not well understood. Using coronal observations from the 2018 off-pointing campaign of the GOES Solar Ultraviolet Imager (SUVI) as well as images from SOHO/LASCO, we found signatures of solar wind streams driven by magnetic reconnection in the highly structured middle corona. In particular, elongated coronal loops in the middle corona over a coronal-hole-active-region complex are observed to reconnect and retract while in the process, some plasma is propelled away from the Sun as streams or blobs. Using STEREO observations we found that similar streams forming over the same complex escape into the heliosphere. Our observations of reconnection effects, however, are limited by the time resolution of the SUVI data in that they clearly represent the tail of a distribution of event durations, with a strong likelihood that many more events remain unresolved in the current data. In this talk, we will present these new results and discuss them in the context of models of slow solar wind sources and drivers. our findings emphasize the key necessity of having routine extreme ultraviolet observations of the middle coronal processes from ecliptic and polar vantage points, along with extended coronal diagnostics to develop better understanding of the heliospheric impact of Sun's activity. Title: The PUNCH Outreach Program A New Pathway for NASA Mission-Embedded Outreach Authors: Morrow, Cherilynn; DeForest, Craig Bibcode: 2021AGUFMED14A..03M Altcode: The NASA PUNCH mission will be uniquely capable of tracking space weather features from the Suns outermost atmosphere all the way to Earth orbit. The NASA Heliophysics Division approved the 5-year PUNCH Outreach Program (POP) for funding in January 2021, referring to it publicly as a new exemplar for mission-embedded outreach. The POP engages PUNCH scientists in partnership with five planetariums and science centers plus other multi-cultural partners to activate an Ancient & Modern Sun Watching theme designed to engage historically marginalized populations. Shortly after NASA selected PUNCH to become a NASA Small Explorer mission, PI Dr. Craig DeForest hired Dr. Cherilynn Morrow as a consultant charged with building an outreach team and developing a plan for an outreach program that would be considered for funding via an augmentation to the mission budget. There were no specific NASA guidelines. The PIs charge was two-fold: 1) to leverage the mission to inspire diverse youth in the US Southwest, and 2) to complement and extend whatever else NASA is doing in this domain. Former NASA policy required Principal Investigators of NASA space science missions to allocate 1-2% of mission costs for a program of education and public outreach (EPO). This policy was supported by contemporary Decadal Survey recommendations from the National Academy. However, the mandate approach to EPO was not fully successful and was eventually discontinued. Understandably, some considered the 1-2% policy a tax on their time and funds in an unfamiliar domain that distracted them from primary science objectives. The current approach by the Heliophysics Division and by the PUNCH project deliberately assuage these concerns to demonstrate effective embedding of an ambitious outreach program within a NASA mission. This talk will share the 8 Guiding Principles of the POP that are enabling PUNCH to realize the unique benefits of an outreach program being closely associated with a NASA space science mission while addressing lessons learned from past efforts and seizing new opportunities afforded by the present landscape of NASA public engagement. These Principles may be of broader value to other scientific leaders and outreach professionals considering whether to pursue support for mission-embedded outreach programs. Title: First observations from the SPICE EUV spectrometer on Solar Orbiter Authors: Fludra, A.; Caldwell, M.; Giunta, A.; Grundy, T.; Guest, S.; Leeks, S.; Sidher, S.; Auchère, F.; Carlsson, M.; Hassler, D.; Peter, H.; Aznar Cuadrado, R.; Buchlin, É.; Caminade, S.; DeForest, C.; Fredvik, T.; Haberreiter, M.; Harra, L.; Janvier, M.; Kucera, T.; Müller, D.; Parenti, S.; Schmutz, W.; Schühle, U.; Solanki, S. K.; Teriaca, L.; Thompson, W. T.; Tustain, S.; Williams, D.; Young, P. R.; Chitta, L. P. Bibcode: 2021A&A...656A..38F Altcode: 2021arXiv211011252F
Aims: We present first science observations taken during the commissioning activities of the Spectral Imaging of the Coronal Environment (SPICE) instrument on the ESA/NASA Solar Orbiter mission. SPICE is a high-resolution imaging spectrometer operating at extreme ultraviolet (EUV) wavelengths. In this paper we illustrate the possible types of observations to give prospective users a better understanding of the science capabilities of SPICE.
Methods: We have reviewed the data obtained by SPICE between April and June 2020 and selected representative results obtained with different slits and a range of exposure times between 5 s and 180 s. Standard instrumental corrections have been applied to the raw data.
Results: The paper discusses the first observations of the Sun on different targets and presents an example of the full spectra from the quiet Sun, identifying over 40 spectral lines from neutral hydrogen and ions of carbon, oxygen, nitrogen, neon, sulphur, magnesium, and iron. These lines cover the temperature range between 20 000 K and 1 million K (10 MK in flares), providing slices of the Sun's atmosphere in narrow temperature intervals. We provide a list of count rates for the 23 brightest spectral lines. We show examples of raster images of the quiet Sun in several strong transition region lines, where we have found unusually bright, compact structures in the quiet Sun network, with extreme intensities up to 25 times greater than the average intensity across the image. The lifetimes of these structures can exceed 2.5 hours. We identify them as a transition region signature of coronal bright points and compare their areas and intensity enhancements. We also show the first above-limb measurements with SPICE above the polar limb in C III, O VI, and Ne VIII lines, and far off limb measurements in the equatorial plane in Mg IX, Ne VIII, and O VI lines. We discuss the potential to use abundance diagnostics methods to study the variability of the elemental composition that can be compared with in situ measurements to help confirm the magnetic connection between the spacecraft location and the Sun's surface, and locate the sources of the solar wind.
Conclusions: The SPICE instrument successfully performs measurements of EUV spectra and raster images that will make vital contributions to the scientific success of the Solar Orbiter mission. Title: Small-Scale Solar Activity and its effect on the coronal environment Authors: Raouafi, Nour; Stenborg, Guillermo; Seaton, Daniel; DeForest, Craig; Bale, Stuart; Horbury, Timothy; Kasper, Justin; Velli, Marco; Karpen, Judith; Kumar, Pankaj; DeVore, C. Richard; Uritsky, Vadim Bibcode: 2021AGUFMSH25F2144R Altcode: Careful analysis of solar observations reveals a myriad of small-scale jetting activity (i.e., jetlets; Raouafi & Stenborg 2014). Jetlets are miniature manifestations of the typical coronal jets observed in both X-rays and extreme-ultraviolet (EUV) solar images. They are the product of near-ubiquitous magnetic reconnection. Their role in energy and mass transport to the solar corona and wind has not been yet well established. Here we provide an overview of this phenomenon and explore its role at the base of the corona and the young solar wind. We conjecture that these small dynamic features might be the source or at least one of the sources of the magnetic switchbacks observed by the Parker Solar Probe. Title: The Sun's dynamic extended corona observed in extreme ultraviolet Authors: Seaton, Daniel B.; Hughes, J. Marcus; Tadikonda, Sivakumara K.; Caspi, Amir; DeForest, Craig E.; Krimchansky, Alexander; Hurlburt, Neal E.; Seguin, Ralph; Slater, Gregory Bibcode: 2021NatAs...5.1029S Altcode: 2021arXiv210508028S; 2021NatAs.tmp..141S The `middle corona' is a critical transition between the highly disparate physical regimes of the lower and outer solar coronae. Nonetheless, it remains poorly understood due to the difficulty of observing this faint region (1.5-3 R⊙). New observations from the Solar Ultraviolet Imager of a Geostationary Operational Environmental Satellite in August and September 2018 provide the first comprehensive look at this region's characteristics and long-term evolution in extreme ultraviolet. Our analysis shows that the dominant emission mechanism here is resonant scattering rather than collisional excitation, consistent with recent model predictions. Our observations highlight that solar wind structures in the heliosphere originate from complex dynamics manifesting in the middle corona that do not occur at lower heights. These data emphasize that low-coronal phenomena can be strongly influenced by inflows from above, not only by photospheric motion, a factor largely overlooked in current models of coronal evolution. This study reveals the full kinematic profile of the initiation of several coronal mass ejections, filling a crucial observational gap that has hindered understanding of the origins of solar eruptions. These new data uniquely demonstrate how extreme ultraviolet observations of the middle corona provide strong new constraints on models seeking to unify the corona and heliosphere. Title: Mesoscale Structure in the Solar Wind Authors: Viall, N. M.; DeForest, C. E.; Kepko, L. Bibcode: 2021FrASS...8..139V Altcode: Structures in the solar wind result from two basic mechanisms: structures injected or imposed directly by the Sun, and structures formed through processing en route as the solar wind advects outward and fills the heliosphere. On the largest scales, solar structures directly impose heliospheric structures, such as coronal holes imposing high speed streams of solar wind. Transient solar processes can inject large-scale structure directly into the heliosphere as well, such as coronal mass ejections. At the smallest, kinetic scales, the solar wind plasma continually evolves, converting energy into heat, and all structure at these scales is formed en route. `Mesoscale' structures, with scales at 1 AU in the approximate spatial range of 5 Mm -10,000 Mm and temporal range of 10 s - 7 hrs, lie in the orders of magnitude gap between the two size-scale extremes. Structures of this size regime are created through both mechanisms. Competition between the imposed and injected structures with turbulent and other evolution leads to complex structuring and dynamics. The goal is to understand this interplay and to determine which type of mesoscale structures dominate the solar wind under which conditions. However, the mesoscale regime is also the region of observation space that is grossly under-sampled. The sparse in situ measurements that currently exist are only able to measure individual instances of discrete structures, and are not capable of following their evolution or spatial extent. Remote imaging has captured global and large scale features and their evolution, but does not yet have the sensitivity to measure most mesoscale structures and their evolution. Similarly, simulations cannot model the global system while simultaneously resolving kinetic effects. It is important to understand the source and evolution of solar wind mesoscale structures because they contain information on how the Sun forms the solar wind, and constrains the physics of turbulent processes. Mesoscale structures also comprise the ground state of space weather, continually buffeting planetary magnetospheres. In this paper we describe the current understanding of the formation and evolution mechanisms of mesoscale structures in the solar wind, their characteristics, implications, and future steps for research progress on this topic. Title: The CubeSat Imaging X-ray Solar Spectrometer (CubIXSS) Authors: Caspi, A.; Shih, A. Y.; Panchapakesan, S.; Warren, H. P.; Woods, T. N.; Cheung, M.; DeForest, C. E.; Klimchuk, J. A.; Laurent, G. T.; Mason, J. P.; Palo, S. E.; Seaton, D. B.; Steslicki, M.; Gburek, S.; Sylwester, J.; Mrozek, T.; Kowaliński, M.; Schattenburg, M.; The CubIXSS Team Bibcode: 2021AAS...23821609C Altcode: The CubeSat Imaging X-ray Solar Spectrometer (CubIXSS) is a 6U CubeSat proposed to NASA H-FORT. CubIXSS is motivated by a compelling overarching science question: what are the origins of hot plasma in solar flares and active regions? Elemental abundances are a unique diagnostic of how mass and energy flow into and within the corona, and CubIXSS addresses its science question through sensitive, precise measurements of abundances of key trace ion species, whose spectral signatures reveal the chromospheric or coronal origins of heated plasma across the entire temperature range from ~1 to >30 MK. CubIXSS measurements of the coronal temperature distribution and elemental abundances directly address longstanding inconsistencies from prior studies using instruments with limited, differing temperature and composition sensitivities.

CubIXSS comprises two co-optimized and cross-calibrated instruments that fill a critical observational gap:

MOXSI, a novel diffractive spectral imager using a pinhole camera and X-ray transmission diffraction grating for spectroscopy of flares and active regions from 1 to 55 Å, with spectral and spatial resolutions of 0.28-0.37 Å and 29-39 arcsec FWHM, respectively; and

SASS, a suite of four spatially-integrated off-the-shelf spectrometers for high-cadence, high-sensitivity X-ray spectra from 0.5 to 50 keV, with spectral resolution of 0.06-0.5 keV FWHM across that range.

If selected for implementation, CubIXSS will launch in late 2023 to mid-2024 to observe intense solar flares and active regions during the rising phase and peak of the solar cycle. Its 1-year prime mission is well timed with perihelia of Parker Solar Probe and Solar Orbiter, and with the launches of complementary missions such as the PUNCH Small Explorer. CubIXSS is a pathfinder for the next generation of Explorer-class missions with improved capabilities for SXR imaging spectroscopy. We present the CubIXSS motivating science background, its suite of instruments and expected performances, and other highlights from the completed Concept Study Report, including novel analysis techniques to fully exploit the rich data set of CubIXSS spectral observations. Title: Cross Sections of Coronal Loop Flux Tubes Authors: Klimchuk, J. A.; DeForest, C. Bibcode: 2021AAS...23832808K Altcode: Coronal loops reveal crucial information about the nature of both coronal magnetic fields and coronal heating. The shape of the corresponding flux tube cross section and how it varies with position are especially important properties. They are a direct indication of the expansion of the field and of the cross-field spatial distribution of the heating. We have studied 20 loops using high spatial resolution observations from the first flight of the Hi-C rocket experiment, measuring the intensity and width as a function of position along the loop axis. We find that intensity and width tend to either be uncorrelated or to have a direct dependence, such that they increase or decrease together. This implies that the flux tube cross sections are approximately circular under the assumptions that the tubes have non-negligible twist and that the plasma emissivity is approximately uniform along the magnetic field. The shape need not be a perfect circle and the emissivity need not be uniform within the cross section, but sub-resolution patches of emission must be distributed quasi-uniformly within an envelope that has an aspect ratio of order unity. This raises questions about the suggestion that flux tubes expand with height, but primarily in the line-of-sight direction so that the corresponding (relatively noticeable) loops appear to have roughly uniform width, a long-standing puzzle. It also casts doubt on the idea that most loops correspond to simple warped sheets, although we leave open the possibility of more complex manifold structures. Title: Fluxon Modeling of the Steady Solar Wind Authors: Lowder, C.; Lamb, D.; DeForest, C. Bibcode: 2021AAS...23822904L Altcode: We describe a novel method for modeling the global, steady solar wind using observed photospheric magnetic fields as a driving boundary condition. The Field Line Universal relaXer (FLUX) numerical code models the solar corona as a collection of magnetic domains, represented by a quasi-Lagrangian grid of discrete field lines (fluxons). Each fluxon represents a quantized bundle of magnetic flux and responds to computed magnetic tension and pressure forces from neighboring fluxons. The model relaxes a collection of fluxons to solve the nonlinear force-free field with a prescribed boundary and topology. Synoptic magnetogram data are used to drive initial fluxon placement and topology, providing the output of an observationally-driven relaxed coronal magnetic field. The FLUX model provides an intermediate approach between rapid heuristic methods and intensive 3D magnetohydrodynamic models, providing the best of both worlds. The FLUX model has the distinct advantages of being computationally efficient (scaling with the magnetic complexity of the two-dimensional photospheric boundary) and preserving connectivity to allow for tracking the history of a bundle of magnetic flux. Open fluxons extending from the photospheric boundary are used to compute a set of modified one-dimensional isothermal Parker solar wind solutions, with transonic solutions interpolated to an outer spherical boundary uniform grid at 21.5 solar radii for comparison with and distribution to other heliospheric models. We describe the method, the simulation code, and solar wind model results. Title: Polarimeter to UNify the Corona and Heliosphere: Science Summary and Mission Status Authors: Deforest, C.; Gibson, S.; Killough, R.; Beasley, M.; Laurent, G.; Colaninno, R.; The Punch Team Bibcode: 2021AAS...23831304D Altcode: The Polarimeter to UNify the Corona and Heliosphere (PUNCH) is a constellation mission being built within NASA's Small Explorer program. During its two year nominal mission, PUNCH will use a constellation of four spacecraft as a single visible-light "virtual coronagraph" with a 90° outer field of view and a 1.25° inner field of view, to continuously produce global, photometric, 3D images of the outer reaches of the solar corona and the solar wind itself. PUNCH uses polarization properties of Thomson scattering to extract 3D information along its single line of sight from near Earth.

The PUNCH science objectives are to understand both (1) how coronal structures become the ambient solar wind, and (2) the dynamic evolution of transient structures within the solar wind. Subtopics include mapping the evolving flow of the solar wind, identifying microstructures and turbulence in the young solar wind, locating the Alfvén surface and other natural boundaries of the corona-heliosphere system, tracking CMEs and their evolution in 3D, measuring the formation of solar wind co-rotating interaction regions, and determining the large-scale dynamics of interplanetary shocks. These are addressed through deep-field 3D imaging, using the polarization properties of Thomson-scattered light.

PUNCH is finishing up its Phase B (preliminary design), with KDP-C expected in 2021 July and a Launch Readiness Date in late 2023.

This poster summarizes the science objectives, novel approach, and current status of the mission. Title: Inward-propagating Plasma Parcels in the Solar Corona: Models with Aerodynamic Drag, Ablation, and Snowplow Accretion Authors: Cranmer, Steven R.; DeForest, Craig E.; Gibson, Sarah E. Bibcode: 2021ApJ...913....4C Altcode: 2021arXiv210312039C Although the solar wind flows primarily outward from the Sun to interplanetary space, there are times when small-scale plasma inflows are observed. Inward-propagating density fluctuations in polar coronal holes were detected by the COR2 coronagraph on board the STEREO-A spacecraft at heliocentric distances of 7-12 solar radii, and these fluctuations appear to undergo substantial deceleration as they move closer to the Sun. Models of linear magnetohydrodynamic waves have not been able to explain these deceleration patterns, so they have been interpreted more recently as jets from coronal sites of magnetic reconnection. In this paper, we develop a range of dynamical models of discrete plasma parcels with the goal of better understanding the observed deceleration trend. We found that parcels with a constant mass do not behave like the observed flows, and neither do parcels undergoing ablative mass loss. However, parcels that accrete mass in a snowplow-like fashion can become decelerated as observed. We also extrapolated OMNI in situ data down to the so-called Alfvén surface and found that the initial launch point for the observed parcels may often be above this critical radius. In other words, in order for the parcels to flow back down to the Sun, their initial speeds are probably somewhat nonlinear (i.e., supra-Alfvénic), and thus the parcels may be associated with structures such as shocks, jets, or shear instabilities. Title: Critical Science Plan for the Daniel K. Inouye Solar Telescope (DKIST) Authors: Rast, Mark P.; Bello González, Nazaret; Bellot Rubio, Luis; Cao, Wenda; Cauzzi, Gianna; Deluca, Edward; de Pontieu, Bart; Fletcher, Lyndsay; Gibson, Sarah E.; Judge, Philip G.; Katsukawa, Yukio; Kazachenko, Maria D.; Khomenko, Elena; Landi, Enrico; Martínez Pillet, Valentín; Petrie, Gordon J. D.; Qiu, Jiong; Rachmeler, Laurel A.; Rempel, Matthias; Schmidt, Wolfgang; Scullion, Eamon; Sun, Xudong; Welsch, Brian T.; Andretta, Vincenzo; Antolin, Patrick; Ayres, Thomas R.; Balasubramaniam, K. S.; Ballai, Istvan; Berger, Thomas E.; Bradshaw, Stephen J.; Campbell, Ryan J.; Carlsson, Mats; Casini, Roberto; Centeno, Rebecca; Cranmer, Steven R.; Criscuoli, Serena; Deforest, Craig; Deng, Yuanyong; Erdélyi, Robertus; Fedun, Viktor; Fischer, Catherine E.; González Manrique, Sergio J.; Hahn, Michael; Harra, Louise; Henriques, Vasco M. J.; Hurlburt, Neal E.; Jaeggli, Sarah; Jafarzadeh, Shahin; Jain, Rekha; Jefferies, Stuart M.; Keys, Peter H.; Kowalski, Adam F.; Kuckein, Christoph; Kuhn, Jeffrey R.; Kuridze, David; Liu, Jiajia; Liu, Wei; Longcope, Dana; Mathioudakis, Mihalis; McAteer, R. T. James; McIntosh, Scott W.; McKenzie, David E.; Miralles, Mari Paz; Morton, Richard J.; Muglach, Karin; Nelson, Chris J.; Panesar, Navdeep K.; Parenti, Susanna; Parnell, Clare E.; Poduval, Bala; Reardon, Kevin P.; Reep, Jeffrey W.; Schad, Thomas A.; Schmit, Donald; Sharma, Rahul; Socas-Navarro, Hector; Srivastava, Abhishek K.; Sterling, Alphonse C.; Suematsu, Yoshinori; Tarr, Lucas A.; Tiwari, Sanjiv; Tritschler, Alexandra; Verth, Gary; Vourlidas, Angelos; Wang, Haimin; Wang, Yi-Ming; NSO and DKIST Project; DKIST Instrument Scientists; DKIST Science Working Group; DKIST Critical Science Plan Community Bibcode: 2021SoPh..296...70R Altcode: 2020arXiv200808203R The National Science Foundation's Daniel K. Inouye Solar Telescope (DKIST) will revolutionize our ability to measure, understand, and model the basic physical processes that control the structure and dynamics of the Sun and its atmosphere. The first-light DKIST images, released publicly on 29 January 2020, only hint at the extraordinary capabilities that will accompany full commissioning of the five facility instruments. With this Critical Science Plan (CSP) we attempt to anticipate some of what those capabilities will enable, providing a snapshot of some of the scientific pursuits that the DKIST hopes to engage as start-of-operations nears. The work builds on the combined contributions of the DKIST Science Working Group (SWG) and CSP Community members, who generously shared their experiences, plans, knowledge, and dreams. Discussion is primarily focused on those issues to which DKIST will uniquely contribute. Title: Plumelets: Dynamic Filamentary Structures in Solar Coronal Plumes Authors: Uritsky, V. M.; DeForest, C. E.; Karpen, J. T.; DeVore, C. R.; Kumar, P.; Raouafi, N. E.; Wyper, P. F. Bibcode: 2021ApJ...907....1U Altcode: 2020arXiv201205728U Solar coronal plumes long seemed to possess a simple geometry supporting spatially coherent, stable outflow without significant fine structure. Recent high-resolution observations have challenged this picture by revealing numerous transient, small-scale, collimated outflows ("jetlets") at the base of plumes. The dynamic filamentary structure of solar plumes above these outflows, and its relationship with the overall plume structure, have remained largely unexplored. We analyzed the statistics of continuously observed fine structure inside a single representative bright plume within a mid-latitude coronal hole during 2016 July 2-3. By applying advanced edge-enhancement and spatiotemporal analysis techniques to extended series of high-resolution images from the Solar Dynamics Observatory's Atmospheric Imaging Assembly, we determined that the plume was composed of numerous time-evolving filamentary substructures, referred to as "plumelets" in this paper, that accounted for most of the plume emission. The number of simultaneously identifiable plumelets was positively correlated with plume brightness, peaked in the fully formed plume, and remained saturated thereafter. The plumelets had transverse widths of 10 Mm and intermittently supported upwardly propagating periodic disturbances with phase speeds of 190-260 km s-1 and longitudinal wavelengths of 55-65 Mm. The characteristic frequency (≍ 3.3 mHz) is commensurate with that of solar p-modes. Oscillations in neighboring plumelets are uncorrelated, indicating that the waves could be driven by p-mode flows at spatial scales smaller than the plumelet separation. Multiple independent sources of outflow within a single coronal plume should impart significant fine structure to the solar wind that may be detectable by Parker Solar Probe and Solar Orbiter. 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: Relative coronal abundance diagnostics with Solar Orbiter/SPICE Authors: Zambrana Prado, N.; Buchlin, E.; Peter, H.; Young, P. R.; Auchere, F.; Carlsson, M.; Fludra, A.; Hassler, D.; Aznar Cuadrado, R.; Caminade, S.; Caldwell, M.; DeForest, C.; Fredvik, T.; Harra, L.; Janvier, M.; Kucera, T. A.; Giunta, A. S.; Grundy, T.; Müller, D.; Parenti, S.; Schmutz, W. K.; Schühle, U.; Sidher, S.; Teriaca, L.; Thompson, W. T.; Williams, D. Bibcode: 2020AGUFMSH038..09Z Altcode: Linking solar activity on the surface and in the corona to the inner heliosphere is one of Solar Orbiter's main goals. Its UV spectrometer SPICE (SPectral Imaging of the Coronal Environment) will provide relative abundance measurements which will be key in this quest as different structures on the Sun have different abundances as a consequence of the FIP (First Ionization Potential) effect. Solar Orbiter's unique combination of remote sensing and in-situ instruments coupled with observation from other missions such as Parker Solar Probe will allow us to compare in-situ and remote sensing composition data. With the addition of modeling, these new results will allow us to trace back the source of heliospheric plasma. As high telemetry will not always be available with SPICE, we have developed a method for measuring relative abundances that is both telemetry efficient and reliable. Unlike methods based on Differential Emission Measure (DEM) inversion, the Linear Combination Ratio (LCR) method does not require a large number of spectral lines. This new method is based on linear combinations of UV spectral lines. The coefficients of the combinations are optimized such that the ratio of two linear combinations of radiances would yield the relative abundance of two elements. We present some abundance diagnostics tested on different combinations of spectral lines observable by SPICE. Title: Contemporary Analysis Methods for Coronagraph and Heliospheric Imager Data Authors: Thompson, B. J.; Attie, R.; Chhiber, R.; Cranmer, S. R.; DeForest, C.; Gallardo-Lacourt, B.; Gibson, S. E.; Jones, S. I.; Moraes Filho, V.; Reginald, N. L.; Uritsky, V. M.; Viall, N. M. Bibcode: 2020AGUFMSH031..05T Altcode: Coronagraphs, polarimeters, and heliospheric imagers are providing new insight into how structures in the solar wind form and develop as they flow from the inner corona into the heliosphere. With this comes a whole new frontier of physical observables in 3D, including kinetic (velocity and acceleration), thermodynamic (density, temperature, and shock boundary), and magnetic field properties. These measurements inform and challenge models of global solar wind flow, turbulence, and CME propagation. We will discuss recent advances in quantifying physical properties of the corona and solar wind using coronagraph and heliospheric imager data, and make predictions of what new models and instrumentation (including the in-development PUNCH mission) will bring us in the future. Title: Dynamics and thermal structure in the quiet Sun seen by SPICE Authors: Peter, H.; Aznar Cuadrado, R.; Schühle, U.; Teriaca, L.; Auchere, F.; Carlsson, M.; Fludra, A.; Hassler, D.; Buchlin, E.; Caminade, S.; Caldwell, M.; DeForest, C.; Fredvik, T.; Harra, L. K.; Janvier, M.; Kucera, T. A.; Giunta, A. S.; Grundy, T.; Müller, D.; Parenti, S.; Schmutz, W. K.; Sidher, S.; Thompson, W. T.; Williams, D.; Young, P. R. Bibcode: 2020AGUFMSH038..03P Altcode: We will present some of the early data of the Spectral Imaging of the Coronal Environment (SPICE) instrument on Solar Orbiter. One of the unique features of SPICE is its capability to record a wide range of wavelengths in the extreme UV with the possibility to record spectral lines giving access to a continuous plasma temperature range from 10.000 K to well above 1 MK. The data taken so far were for commissioning purposes and they can be used for a preliminary evaluation of the science performance of the instrument. Here we will concentrate on sample spectra covering the whole wavelength region and on the early raster maps acquired in bright lines in the quiet Sun close to disk center. Looking at different quiet Sun features we investigate the thermal structure of the atmosphere and flow structures. For this we apply fits to the spectral profiles and check the performance in terms of Doppler shifts and line widths to retrieve the structure of the network in terms of dynamics. While the amount of data available so far is limited, we will have a first look on how quiet Sun plasma responds to heating events. For this, we will compare spectral lines forming at different temperatures recorded at strictly the same time. Title: The CubeSat Imaging X-ray Solar Spectrometer (CubIXSS) Authors: Caspi, A.; Shih, A. Y.; Warren, H.; Winebarger, A. R.; Woods, T. N.; Cheung, C. M. M.; DeForest, C.; Klimchuk, J. A.; Laurent, G. T.; Mason, J. P.; Palo, S. E.; Schwartz, R.; Seaton, D. B.; Steslicki, M.; Gburek, S.; Sylwester, J.; Mrozek, T.; Kowaliński, M.; Schattenburg, M. Bibcode: 2020AGUFMSH0480007C Altcode: The CubeSat Imaging X-ray Solar Spectrometer (CubIXSS) is a 6U CubeSat currently in a formulation phase under the 2019 NASA H-FORT program. CubIXSS is motivated by a compelling overarching science question: what are the origins of hot plasma in solar flares and active regions? Elemental abundances are a unique diagnostic of how mass and energy flow into and within the corona, and CubIXSS addresses its science question through sensitive, precise measurements of abundances of key trace ion species, whose spectral signatures reveal the chromospheric or coronal origins of heated plasma across the entire range of coronal temperatures, from ~1 to >30 MK. CubIXSS measurements of the coronal temperature distribution and elemental abundances directly address longstanding inconsistencies from prior studies using instruments with limited, differing temperature and composition sensitivities.

CubIXSS comprises two co-optimized and cross-calibrated instruments that fill a critical observational gap:

MOXSI, a novel diffractive spectral imager using a pinhole camera and X-ray transmission diffraction grating to achieve spectroscopy of flares and active regions from 1 to 55 Å, with spectral resolution of 0.24 Å FWHM and a spatial resolution of 25 arcsec FWHM; and

SASS, a suite of four spatially-integrated off-the-shelf spectrometers for high-cadence, high-sensitivity measurements of soft and hard X-rays, from 0.5 to 50 keV, with spectral resolution from 0.06 to 0.5 keV FWHM.

If selected for implementation, CubIXSS will launch in mid-2023 to observe intense solar flares and active regions during the rising phase of the solar cycle. Its nominal 1-year mission is well timed with perihelia of Parker Solar Probe and Solar Orbiter, and with the launches of complementary missions such as the PUNCH Small Explorer. CubIXSS is also a pathfinder for the next generation of Explorer-class missions with improved capabilities for SXR imaging spectroscopy. We present the CubIXSS motivating science background, its suite of instruments and expected performances, and other highlights from the completed Concept Study Report, including novel analysis techniques to fully exploit the rich data set of CubIXSS spectral observations. Title: Why (And How) We Should Observe The Dynamic Middle Corona Authors: Seaton, D. B.; Caspi, A.; DeForest, C.; Hughes, M. Bibcode: 2020AGUFMSH0300001S Altcode: Although the solar corona is the primary driver of almost all plasma dynamics throughout the solar system, the precise nature of the connection between the corona and heliosphere remains poorly understood. Parker Solar Probe observations from 0.3 AU have revealed a highly structured environment shaped by flows and ejecta interacting with the corona's complex magnetic field. Critically, significant physical transitions in the middle corona — i.e. from closed to open magnetic field and, in some locations, low to high plasma beta — govern the overall connectivity between the inner corona and heliosphere. However, observations of this region remain scarce, and completely connecting PSP observations to the low corona remains a challenge. New approaches to observations, particularly in the EUV, can fully reveal this region, its dynamics, and connectivity to the outer corona, opening the door to resolving a decades-old mystery about the relationship between the solar wind, solar eruptions, and the low corona. In this talk we demonstrate how new observations will lead to the development of coherent understanding of the corona and heliosphere as a single system in a region where deep connections have previously only been inferred. We discuss the variability of the middle corona we see in these observations, and what this variability reveals about the importance of the evolving Sun's influence on the heliosphere as a whole. Title: First Results From SPICE EUV Spectrometer on Solar Orbiter Authors: Fludra, A.; Caldwell, M.; Giunta, A. S.; Grundy, T.; Guest, S.; Sidher, S.; Auchere, F.; Carlsson, M.; Hassler, D.; Peter, H.; Aznar Cuadrado, R.; Buchlin, E.; Caminade, S.; DeForest, C.; Fredvik, T.; Harra, L. K.; Janvier, M.; Kucera, T. A.; Leeks, S.; Mueller, D.; Parenti, S.; Schmutz, W. K.; Schühle, U.; Teriaca, L.; Thompson, W. T.; Tustain, S.; Williams, D.; Young, P. R. Bibcode: 2020AGUFMSH038..02F Altcode: SPICE (Spectral Imaging of Coronal Environment) is one of the remote sensing instruments onboard Solar Orbiter. It is an EUV imaging spectrometer observing the Sun in two wavelength bands: 69.6-79.4 nm and 96.6-105.1 nm. SPICE is capable of recording full spectra in these bands with exposures as short as 1s. SPICE is the only Solar Orbiter instrument that can measure EUV spectra from the disk and low corona of the Sun and record all spectral lines simultaneously. SPICE uses one of three narrow slits, 2"x11', 4''x11', 6''x11', or a wide slit 30''x14'. The primary mirror can be scanned in a direction perpendicular to the slit, allowing raster images of up to 16' in size.

We present an overview of the first SPICE data taken on several days during the instrument commissioning carried out by the RAL Space team between 2020 April 21 and 2020 June 14. We also include results from SPICE observations at the first Solar Orbiter perihelion at 0.52AU, taken between June 16-21st. We give examples of full spectra from the quiet Sun near disk centre and provide a list of key spectral lines emitted in a range of temperatures between 10,000 K and over 1 million K, from neutral hydrogen and ions of carbon, oxygen, nitrogen, neon, sulphur and magnesium. We show examples of first raster images in several strong lines, obtained with different slits and a range of exposure times between 5s and 180s. We describe the temperature coverage and density diagnostics, determination of plasma flows, and discuss possible applications to studies of the elemental abundances in the corona. We also show the first off-limb measurements with SPICE, as obtained when the spacecraft pointed at the limb. Title: New Insights into the Dynamic Relationship between Jetlets and Plumes Authors: Kumar, P.; Karpen, J. T.; Uritsky, V. M.; DeForest, C.; Raouafi, N. E.; DeVore, C. R. Bibcode: 2020AGUFMSH0240002K Altcode: Plumes are among the most fascinating large-scale coronal structures, but also are among the most puzzling and controversial features. They are significantly denser and have lower flow speeds than the inter-plume regions, and are rooted in regions of fine-scale, highly mixed magnetic polarity within predominantly unipolar coronal holes. The advent of high-resolution, high-cadence coronal observations from the Solar Dynamics Observatory's Atmospheric Imaging Assembly (SDO/AIA), coupled with photospheric magnetograms from SDO's Helioseismic and Magnetic Imager (SDO/HMI), has enabled detailed studies of plumes from their footprints outward. In particular, the detection of small transient outflows at the base of a few plumes led to the hypothesis that these "jetlets" are the long-sought source of plume mass and energy that sustain them for hours to weeks (Raouafi & Stenborg 2014). We have analyzed high-cadence multiwavelength SDO/AIA data and SDO/HMI magnetograms for a well-observed plume on 2016 July 3, focusing on the activity at the base and the fine structure within the overlying plume. In contrast to earlier studies, we used a noise-gating method (DeForest 2017) to clean the AIA and HMI data that revealed in greater detail the jetlets and other small-scale structures throughout the plume. Our investigation revealed multiple quasi-periodic jetlets within the multipolar footpoint region, throughout the period of observation, as well as evolving filamentary structures above the jetlets. This presentation will discuss the measured and derived jetlet properties, the structural and dynamic connections between the jetlets and the plume, and implications for the underlying physical processes.

DeForest C. E., Noise-gating to Clean Astrophysical Image Data, ApJ, 838, 155 (2017)

Raouafi, N. E. & G. Stenborg, Role of Transients in the Sustainability of Solar Coronal Plumes, ApJ, 787, 118 (2014) Title: Velocity Flow Fields Derived from Coronagraph Data Authors: Moraes Filho, V.; DeForest, C.; Thompson, B. J.; Uritsky, V. M. Bibcode: 2020AGUFMSH0280004M Altcode: In anticipation of the PUNCH mission, we examine deep exposure data from the special campaign of the STEREO SECCHI COR2 instrument. Data collected over April 14-16, 2014, representing altitudes of 4-15 solar radii, show clear flow structures throughout the field of view. We examine the variations in the derived flow as a function of altitude and polar angle, to present a picture of the solar wind velocities and acceleration through the corona and inner heliosphere. Title: Plumelets: Dynamic Filamentary Structures in Solar Plumes Authors: Karpen, J. T.; Uritsky, V. M.; DeForest, C.; DeVore, C. R.; Kumar, P.; Raouafi, N. E.; Wyper, P. F. Bibcode: 2020AGUFMSH0240003K Altcode: Solar plumes long seemed to possess a simple geometry supporting spatially coherent, stable outflow without significant fine structure. Recent high-resolution observations have challenged this picture by revealing numerous transient, small-scale, collimated outflows ("jetlets") at the base of plumes (see Kumar et al. presentation in this session). The dynamic filamentary structure of solar plumes above these outflows, and its relationship with the overall plume structure, have remained largely unexplored. We report a statistical analysis of continuously observed fine structure inside a bright plume within a mid-latitude coronal hole during 2016 July 2-3. By applying advanced edge-enhancement and spatiotemporal analysis techniques to extended series of highresolution images from the Solar Dynamics Observatory's Atmospheric Imaging Assembly, we determined that the plume was composed of numerous time-evolving bright filamentary substructures, referred to as "plumelets" in this paper, that accounted for most of the plume emission. The number of simultaneously identifiable plumelets varied over the observation period, was positively correlated with plume brightness, and peaked in the fully formed plume. The plumelets had transverse widths of 10 Mm and intermittently supported upwardly propagating periodic disturbances with phase speeds of 190-260 km s-1 and longitudinal wavelengths of 55-65 Mm. The characteristic frequency (3.5 mHz) is commensurate with that of solar p-modes. Oscillations in neighboring plumelets are uncorrelated, indicating that the waves could be driven by p-mode flows at spatial scales smaller than the plumelet separation. Multiple independent sources of outflow within a single coronal plume should impart significant fine structure to the fast solar wind and be detectable by Parker Solar Probe at perihelion. Title: Shear-Driven Transition to Isotropically Turbulent Solar Wind Outside the Alfvén Critical Zone Authors: Ruffolo, D. J.; Matthaeus, W. H.; Chhiber, R.; Usmanov, A. V.; Yang, Y.; Bandyopadhyay, R.; Parashar, T.; Goldstein, M. L.; DeForest, C.; Wan, M.; Chasapis, A.; Maruca, B.; Velli, M. C. M.; Kasper, J. C. Bibcode: 2020AGUFMSH0290010R Altcode: Motivated by prior remote observations of a transition from striated solar coronal structures to more isotropic "flocculated" fluctuations, we propose that the dynamics of the inner solar wind just outside the Alfvén critical zone, and in the vicinity of the first β=1 surface, is powered by the relative velocities of adjacent coronal magnetic flux tubes. We suggest that large amplitude flow contrasts are magnetically constrained at lower altitude but shear-driven dynamics are triggered as such constraints are released above the Alfvén critical zone, as suggested by global magnetohydrodynamic (MHD) simulations that include self-consistent turbulence transport. We argue that this dynamical evolution accounts for features observed by Parker Solar Probe ( PSP) near initial perihelia, including magnetic "switchbacks", and large transverse velocities that are partially corotational and saturate near the local Alfvén speed. Large-scale magnetic increments are more longitudinal than latitudinal, a state unlikely to originate in or below the lower corona. We attribute this to preferentially longitudinal velocity shear from varying degrees of corotation. Supporting evidence includes comparison with a high Mach number three-dimensional compressible MHD simulation of nonlinear shear-driven turbulence, reproducing several observed diagnostics, including characteristic distributions of fluctuations that are qualitatively similar to PSP observations near the first perihelion. The concurrence of evidence from remote sensing observations, in situ measurements, and both global and local simulations supports the idea that the dynamics just above the Alfvén critical zone boost low-frequency plasma turbulence to the level routinely observed throughout the explored solar system. This research has been supported in part by grant RTA6280002 from Thailand Science Research and Innovation and the Parker Solar Probe mission under the ISOIS project (contract NNN06AA01C) and a subcontract to University of Delaware from Princeton University (SUB0000165). M.L.G. acknowledges support from the Parker Solar Probe FIELDS MAG team. Y.Y. is supported in part by NSFC grant 11902138. Additional support is acknowledged from the NASA LWS program (NNX17AB79G) and the HSR program (80NSSC18K1210 & 80NSSC18K1648). Title: Cross Sections of Coronal Loop Flux Tubes Authors: Klimchuk, J. A.; DeForest, C. Bibcode: 2020AGUFMSH0370001K Altcode: Coronal loops reveal crucial information about the nature of both coronal magnetic fields and coronal heating. The shape of the corresponding flux tube cross section and how it varies with position are especially important properties. They are a direct indication of the expansion of the field and of the cross-field spatial distribution of the heating. We have studied 20 loops using high spatial resolution observations from the first flight of the Hi-C rocket experiment, measuring the intensity and width as a function of position along the loop axis. We find that intensity and width tend to either be uncorrelated or to have a direct dependence, such that they increase or decrease together. This implies that the flux tube cross sections are approximately circular under the assumptions that the tubes have non-negligible twist and that the plasma emissivity is approximately uniform along the magnetic field. The shape need not be a perfect circle and the emissivity need not be uniform within the cross section, but sub-resolution patches of emission must be distributed quasi-uniformly within an envelope that has an aspect ratio of order unity. This raises questions about the suggestion that flux tubes expand with height, but primarily in the line-of-sight direction so that the corresponding (relatively noticeable) loops appear to have roughly uniform width, a long-standing puzzle. It also casts doubt on the idea that most loops correspond to simple warped sheets, although we leave open the possibility of more complex manifold structures. Title: Improving Multiday Solar Wind Forecasts Authors: Elliott, H. A.; Arge, C. N.; Henney, C. J.; Dayeh, M. A.; Livadiotis, G.; Jahn, J. M.; DeForest, C. Bibcode: 2020AGUFMSM030..01E Altcode: No abstract at ADS Title: The Polarimeter to UNify the Corona and Heliosphere (PUNCH) Small Explorer Mission: Status and Next Steps Authors: DeForest, C. E.; Killough, R.; Gibson, S. E.; Beasley, M.; Henry, A.; Laurent, G. T.; Colaninno, R. C. Bibcode: 2020AGUFMSH0280002D Altcode: The Polarimeter to UNify the Corona and Heliosphere (PUNCH) is a NASA Small Explorer mission, to understand the solar corona and young solar wind as a complete system. Science objectives are to measure and understand how the ambient solar wind arises from the corona, and to understand how transient events (such as CMEs) propagate and evolve in the inner heliosphere. PUNCH uses direct, global, spatially continuous, three dimensional imaging in polarized visible light, to observe the outer corona and inner heliosphere as elements of a single, connected system. PUNCH comprises four matched and synchronized small-satellite observatories, operating as a "virtual instrument" to image Thomson-scattered light from low-Earth orbit. PUNCH is the first coronal and solar wind imaging mission designed specifically to produce 3D images from a single vantage point using the polarization properties of Thomson scattering. In addition, it will produce routine, several-times-per-day maps of solar wind flow throughout the top of the corona and bottom of the inner heliosphere, based on motion analysis of the image stream. PUNCH has an open data policy and is seeking scientific engagement throughout the heliophysics community.

PUNCH is wrapping up its Phase B (preliminary design), and is working toward a 2023 launch for a two-year nominal mission. We present a very brief overview of the mission, describe current status and next steps, and indicate how to engage with the PUNCH science team and upcoming mission. Title: Calibrating optical distortions in the Solar Orbiter SPICE spectrograph Authors: Thompson, W. T.; Schühle, U.; Young, P. R.; Auchere, F.; Carlsson, M.; Fludra, A.; Hassler, D.; Peter, H.; Aznar Cuadrado, R.; Buchlin, E.; Caldwell, M.; DeForest, C.; Fredvik, T.; Harra, L. K.; Janvier, M.; Kucera, T. A.; Giunta, A. S.; Grundy, T.; Müller, D.; Parenti, S.; Caminade, S.; Schmutz, W. K.; Teriaca, L.; Williams, D.; Sidher, S. Bibcode: 2020AGUFMSH0360029T Altcode: The Spectral Imaging of the Coronal Environment (SPICE) instrument on Solar Orbiter is a high-resolution imaging spectrometer operating at extreme ultraviolet (EUV) wavelengths from 70.4-79.0 nm and 97.3-104.9 nm. A single-mirror off-axis paraboloid focuses the solar image onto the entrance slit of the spectrometer section. A Toroidal Variable Line Space (TVLS) grating images the entrance slit onto a pair of MCP-intensified APS detectors. Ray-tracing analysis prior to launch showed that the instrument was subject to a number of small image distortions which need to be corrected in the final data product. We compare the ray tracing results with measurements made in flight. Co-alignment with other telescopes on Solar Orbiter will also be examined. Title: First results from the EUI and SPICE observations of Alpha Leo near Solar Orbiter first perihelion Authors: Buchlin, E.; Teriaca, L.; Giunta, A. S.; Grundy, T.; Andretta, V.; Auchere, F.; Peter, H.; Berghmans, D.; Carlsson, M.; Fludra, A.; Harra, L.; Hassler, D.; Long, D.; Rochus, P. L.; Schühle, U.; Aznar Cuadrado, R.; Caldwell, M.; Caminade, S.; DeForest, C.; Fredvik, T.; Gissot, S.; Heerlein, K.; Janvier, M.; Kraaikamp, E.; Kucera, T. A.; Müller, D.; Parenti, S.; Schmutz, W. K.; Sidher, S.; Smith, P.; Stegen, K.; Thompson, W. T.; Verbeeck, C.; Williams, D.; Young, P. R. Bibcode: 2020AGUFMSH0360024B Altcode: On June 16th 2020 Solar Orbiter made a dedicated observing campaign where the spacecraft pointed to the solar limb to allow some of the high resolution instruments to observe the ingress (at the east limb) and later the egress (west limb) of the occultation of the star Alpha Leonis by the solar disk. The star was chosen because its luminosity and early spectral type ensure high and stable flux at wavelengths between 100 and 122 nanometers, a range observed by the High Resolution EUI Lyman alpha telescope (HRI-LYA) and by the long wavelength channel of the SPICE spectrograph. Star observations, when feasible, allow to gather a great deal of information on the instrument performances, such as the radiometric performance and the instrument optical point spread function (PSF).

We report here the first results from the above campaign for the two instruments. Title: Spectroscopic Constraints on the Dimension of Active Region Loops Along the Line of Sight Authors: Kucera, T. A.; Young, P. R.; Klimchuk, J. A.; DeForest, C. Bibcode: 2020AGUFMSH041..05K Altcode: Understanding the cross sections of coronal loops and how they vary along the loop is important both for understanding coronal heating and how the loops are shaped by the coronal magnetic field. To better address this question we have developed a new method to constrain the dimension of loops along the line of sight by utilizing spectroscopic observations. We apply this method to a cool (5.5<logT<6.2) loop using data from the Hinode/EUV Imaging Spectrometer (EIS) with supporting data from Solar Dynamic Observatory (SDO) and the Solar TErrestrial RElations Observatory (STEREO), and discuss the results and their limitations. Our results are consistent with circular loop cross sections, but could also be consistent with aspect ratios of 2 or 3. Title: First results from combined EUI and SPICE observations of Lyman lines of Hydrogen and He II Authors: Teriaca, L.; Aznar Cuadrado, R.; Giunta, A. S.; Grundy, T.; Parenti, S.; Auchere, F.; Vial, J. C.; Fludra, A.; Berghmans, D.; Carlsson, M.; Harra, L.; Hassler, D.; Long, D.; Peter, H.; Rochus, P. L.; Schühle, U.; Buchlin, E.; Caldwell, M.; Caminade, S.; DeForest, C.; Fredvik, T.; Gissot, S.; Heerlein, K.; Janvier, M.; Kraaikamp, E.; Kucera, T. A.; Mueller, D.; Schmutz, W. K.; Sidher, S.; Smith, P.; Stegen, K.; Thompson, W. T.; Verbeeck, C.; Williams, D.; Young, P. R. Bibcode: 2020AGUFMSH0360003T Altcode: The Solar Orbiter spacecraft carries a powerful set of remote sensing instruments that allow studying the solar atmosphere with unprecedented diagnostic capabilities. Many such diagnostics require the simultaneous usage of more than one instrument. One example of that is the capability, for the first time, to obtain (near) simultaneous spatially resolved observations of the emission from the first three lines of the Lyman series of hydrogen and of He II Lyman alpha. In fact, the SPectral Imaging of the Coronal Environment (SPICE) spectrometer can observe the Lyman beta and gamma lines in its long wavelength (SPICE-LW) channel, the High Resolution Lyman Alpha (HRI-LYA) telescope of the Extreme Ultraviolet Imager (EUI) acquires narrow band images in the Lyman alpha line while the Full Disk Imager (FSI) of EUI can take images dominated by the Lyman alpha line of ionized Helium at 30.4 nm (FSI-304). Being hydrogen and helium the main components of our star, these very bright transitions play an important role in the energy budget of the outer atmosphere via radiative losses and the measurement of their profiles and radiance ratios is a fundamental constraint to any comprehensive modelization effort of the upper solar chromosphere and transition region. Additionally, monitoring their average ratios can serve as a check out for the relative radiometric performance of the two instruments throughout the mission. Although the engineering data acquired so far are far from ideal in terms of time simultaneity (often only within about 1 h) and line coverage (often only Lyman beta was acquired by SPICE and not always near simultaneous images from all three telescopes are available) the analysis we present here still offers a great opportunity to have a first look at the potential of this diagnostic from the two instruments. In fact, we have identified a series of datasets obtained at disk center and at various positions at the solar limb that allow studying the Lyman alpha to beta radiance ratio and their relation to He II 30.4 as a function of the position on the Sun (disk center versus limb and quiet Sun versus coronal holes). Title: Shear-driven Transition to Isotropically Turbulent Solar Wind Outside the Alfvén Critical Zone Authors: Ruffolo, D.; Matthaeus, W. H.; Chhiber, R.; Usmanov, A. V.; Yang, Y.; Bandyopadhyay, R.; Parashar, T. N.; Goldstein, M. L.; DeForest, C. E.; Wan, M.; Chasapis, A.; Maruca, B. A.; Velli, M.; Kasper, J. C. Bibcode: 2020ApJ...902...94R Altcode: 2020arXiv200906537R Motivated by prior remote observations of a transition from striated solar coronal structures to more isotropic "flocculated" fluctuations, we propose that the dynamics of the inner solar wind just outside the Alfvén critical zone, and in the vicinity of the first $\beta =1$ surface, is powered by the relative velocities of adjacent coronal magnetic flux tubes. We suggest that large-amplitude flow contrasts are magnetically constrained at lower altitude but shear-driven dynamics are triggered as such constraints are released above the Alfvén critical zone, as suggested by global magnetohydrodynamic (MHD) simulations that include self-consistent turbulence transport. We argue that this dynamical evolution accounts for features observed by Parker Solar Probe (PSP) near initial perihelia, including magnetic "switchbacks," and large transverse velocities that are partially corotational and saturate near the local Alfvén speed. Large-scale magnetic increments are more longitudinal than latitudinal, a state unlikely to originate in or below the lower corona. We attribute this to preferentially longitudinal velocity shear from varying degrees of corotation. Supporting evidence includes comparison with a high Mach number three-dimensional compressible MHD simulation of nonlinear shear-driven turbulence, reproducing several observed diagnostics, including characteristic distributions of fluctuations that are qualitatively similar to PSP observations near the first perihelion. The concurrence of evidence from remote sensing observations, in situ measurements, and both global and local simulations supports the idea that the dynamics just above the Alfvén critical zone boost low-frequency plasma turbulence to the level routinely observed throughout the explored solar system. Title: The Solar Orbiter SPICE instrument. An extreme UV imaging spectrometer Authors: SPICE Consortium; Anderson, M.; Appourchaux, T.; Auchère, F.; Aznar Cuadrado, R.; Barbay, J.; Baudin, F.; Beardsley, S.; Bocchialini, K.; Borgo, B.; Bruzzi, D.; Buchlin, E.; Burton, G.; Büchel, V.; Caldwell, M.; Caminade, S.; Carlsson, M.; Curdt, W.; Davenne, J.; Davila, J.; Deforest, C. E.; Del Zanna, G.; Drummond, D.; Dubau, J.; Dumesnil, C.; Dunn, G.; Eccleston, P.; Fludra, A.; Fredvik, T.; Gabriel, A.; Giunta, A.; Gottwald, A.; Griffin, D.; Grundy, T.; Guest, S.; Gyo, M.; Haberreiter, M.; Hansteen, V.; Harrison, R.; Hassler, D. M.; Haugan, S. V. H.; Howe, C.; Janvier, M.; Klein, R.; Koller, S.; Kucera, T. A.; Kouliche, D.; Marsch, E.; Marshall, A.; Marshall, G.; Matthews, S. A.; McQuirk, C.; Meining, S.; Mercier, C.; Morris, N.; Morse, T.; Munro, G.; Parenti, S.; Pastor-Santos, C.; Peter, H.; Pfiffner, D.; Phelan, P.; Philippon, A.; Richards, A.; Rogers, K.; Sawyer, C.; Schlatter, P.; Schmutz, W.; Schühle, U.; Shaughnessy, B.; Sidher, S.; Solanki, S. K.; Speight, R.; Spescha, M.; Szwec, N.; Tamiatto, C.; Teriaca, L.; Thompson, W.; Tosh, I.; Tustain, S.; Vial, J. -C.; Walls, B.; Waltham, N.; Wimmer-Schweingruber, R.; Woodward, S.; Young, P.; de Groof, A.; Pacros, A.; Williams, D.; Müller, D. Bibcode: 2020A&A...642A..14S Altcode: 2019arXiv190901183A; 2019arXiv190901183S
Aims: The Spectral Imaging of the Coronal Environment (SPICE) instrument is a high-resolution imaging spectrometer operating at extreme ultraviolet wavelengths. In this paper, we present the concept, design, and pre-launch performance of this facility instrument on the ESA/NASA Solar Orbiter mission.
Methods: The goal of this paper is to give prospective users a better understanding of the possible types of observations, the data acquisition, and the sources that contribute to the instrument's signal.
Results: The paper discusses the science objectives, with a focus on the SPICE-specific aspects, before presenting the instrument's design, including optical, mechanical, thermal, and electronics aspects. This is followed by a characterisation and calibration of the instrument's performance. The paper concludes with descriptions of the operations concept and data processing.
Conclusions: The performance measurements of the various instrument parameters meet the requirements derived from the mission's science objectives. The SPICE instrument is ready to perform measurements that will provide vital contributions to the scientific success of the Solar Orbiter mission. Title: Cross Sections of Coronal Loop Flux Tubes Authors: Klimchuk, James A.; DeForest, Craig E. Bibcode: 2020ApJ...900..167K Altcode: 2020arXiv200715085K Coronal loops reveal crucial information about the nature of both coronal magnetic fields and coronal heating. The shape of the corresponding flux tube cross section and how it varies with position are especially important properties. They are a direct indication of the expansion of the field and of the cross-field spatial distribution of the heating. We have studied 20 loops using high spatial resolution observations from the first flight of the Hi-C rocket experiment, measuring the intensity and width as a function of position along the loop axis. We find that intensity and width tend to either be uncorrelated or to have a direct dependence, such that they increase or decrease together. This implies that the flux tube cross sections are approximately circular under the assumptions that the tubes have nonnegligible twist and that the plasma emissivity is approximately uniform along the magnetic field. The shape need not be a perfect circle and the emissivity need not be uniform within the cross section, but subresolution patches of emission must be distributed quasi-uniformly within an envelope that has an aspect ratio of order unity. This raises questions about the suggestion that flux tubes expand with height, but primarily in the line-of-sight direction so that the corresponding (relatively noticeable) loops appear to have roughly uniform width, a long-standing puzzle. It also casts doubt on the idea that most loops correspond to simple warped sheets, although we leave open the possibility of more complex manifold structures. Title: A New Facility for Airborne Solar Astronomy: NASA's WB-57 at the 2017 Total Solar Eclipse Authors: Caspi, Amir; Seaton, Daniel B.; Tsang, Constantine C. C.; DeForest, Craig E.; Bryans, Paul; DeLuca, Edward E.; Tomczyk, Steven; Burkepile, Joan T.; Casey, Thomas "Tony"; Collier, John; Darrow, Donald "DD"; Del Rosso, Dominic; Durda, Daniel D.; Gallagher, Peter T.; Golub, Leon; Jacyna, Matthew; Johnson, David "DJ"; Judge, Philip G.; Klemm, Cary "Diddle"; Laurent, Glenn T.; Lewis, Johanna; Mallini, Charles J.; Parent, Thomas "Duster"; Propp, Timothy; Steffl, Andrew J.; Warner, Jeff; West, Matthew J.; Wiseman, John; Yates, Mallory; Zhukov, Andrei N.; NASA WB-57 2017 Eclipse Observing Team Bibcode: 2020ApJ...895..131C Altcode: 2020arXiv200409658C NASA's WB-57 High Altitude Research Program provides a deployable, mobile, and stratospheric platform for scientific research. Airborne platforms are of particular value for making coronal observations during total solar eclipses because of their ability both to follow the Moon's shadow and to get above most of the atmospheric air mass that can interfere with astronomical observations. We used the 2017 August 21 eclipse as a pathfinding mission for high-altitude airborne solar astronomy, using the existing high-speed visible-light and near/midwave infrared imaging suite mounted in the WB-57 nose cone. In this paper, we describe the aircraft, the instrument, and the 2017 mission; operations and data acquisition; and preliminary analysis of data quality from the existing instrument suite. We describe benefits and technical limitations of this platform for solar and other astronomical observations. We present a preliminary analysis of the visible-light data quality and discuss the limiting factors that must be overcome with future instrumentation. We conclude with a discussion of lessons learned from this pathfinding mission and prospects for future research at upcoming eclipses, as well as an evaluation of the capabilities of the WB-57 platform for future solar astronomy and general astronomical observation. Title: Imaging the Solar Corona From Within Authors: Hess, P.; Howard, R.; Vourlidas, A.; Bothmer, V.; Colaninno, R.; DeForest, C.; Gallagher, B.; Hall, J. R.; Higginson, A.; Korendyke, C.; Kouloumvakos, A.; Lamy, P.; Liewer, P.; Linker, J.; Linton, M.; Penteado, P.; Plunkett, S.; Poirer, N.; Raouafi, N.; Rich, N.; Rochus, P.; Rouillard, A.; Socker, D.; Stenborg, G.; Thernisien, A.; Viall, N. Bibcode: 2020AAS...23514907H Altcode: Parker Solar Probe (PSP), launched, in August 2018 is humanity's first probe of a stellar atmosphere. It will make measurements of the near-Sun plasma from 'within' the outer corona with gradually reduced perihelia from its first perihelia of 35 Rs in 2018-19 to 9.8 Rs in 2025. Here we report the results from the imaging observations of the electron and dust corona, whe PSP was 35-54 Rs from the solar surface, taken by the Wide-field Imager for Solar Probe (WISPR). The spacecraft was near-corotating with the solar corona throughout the observing window, which is an unprecedented situation for any type of coronal imaging. Our initial analysis uncovers a long-hypothesized depletion of the primordial dust orbiting near the Sun, reveals the plasma structure of small-scale ejections, and provides a strict test for validating model predictions of the large-scale configuration of the coronal plasma. Thus, WISPR imaging allows the study of near-Sun dust dynamics as the mission progresses. The high-resolution images of small transients, largely unresolved from 1 AU orbits, unravel the sub-structures of small magnetic flux ropes and show that the Sun continually releases helical magnetic fields in the background wind. Finally, WISPR's observations of the coronal streamer evolution confirm the large-scale topology of the solar corona but they also reveal that, as recently predicted, streamers are composed of yet smaller sub-streamers channeling continual density fluctuations at all visible scales. Title: Narrow Field Imager (NFI) for the Polarimeter to Unify the Corona and Heliosphere (PUNCH) Authors: Colaninno, R. C.; Howard, R. A.; McMullin, D. R.; Carter, M. T.; Thernisien, A.; DeForest, C.; Laurent, G. T.; Beasley, M.; Dancheck, J.; Hagood, R.; Eisenhower, K.; Hunt, T.; Chua, D. H.; Brechbiel, D.; Noya, M. Bibcode: 2019AGUFMSH41E3300C Altcode: The Narrow Field Imager (NFI) is a coronagraph designed as part of Polarimeter to Unify the Corona and Heliosphere (PUNCH) to providing the first complete, photometric, high-resolution views of the corona/solar wind transition. The PUNCH payload also includes three Wide Field Imagers (WFIs) heliospheric images provided by the Southwest Research Institute (SwRI). Together, these instruments form a single "virtual instrument" covering the entire inner solar system continuously from 6 to 180 R⊙ (1.5°-45° solar elongation). Each instrument will be hosted on a 1+3 microsatellite constellation deployed into sun-synchronous LEO. NFI implements a high heritage coronagraph design to observe the inner heliosphere from 5.4 - 32 Rʘ with an annular, sun-centered FOV. NFI achieves the PUNCH required performance within the microsatellite mission concept with a simplified design that exploits heritage from previous space-borne coronagraphs, including SOHO/LASCO C3 and STEREO/SECCHI, and extensive design effort for the similar NOAA Compact Coronagraph (CCOR). We prototyped and tested the NFI stray-light suppression assembly (SSA) at NRL which confirms the expected performance of the SSA and demonstrates the simplified NFI design for the specific application to PUNCH.

This work was sponsored by NASA and the Chief of Naval Research. Title: Imaging the Solar Corona from Within: First Results from the Parker Solar Probe Telescope Authors: Howard, R. A.; Vourlidas, A.; Bothmer, V.; Colaninno, R. C.; DeForest, C.; Gallagher, B.; Hall, J. R.; Hess, P.; Higginson, A. K.; Korendyke, C.; Kouloumvakos, A.; Lamy, P.; Liewer, P. C.; Linker, J.; Linton, M.; Penteado, P. F.; Plunkett, S. P.; Poirier, N.; Raouafi, N.; Rich, N.; Rochus, P. L.; Rouillard, A. P.; Socker, D. G.; Stenborg, G.; Thernisien, A.; Viall, N. M. Bibcode: 2019AGUFMSH11A..04H Altcode: Parker Solar Probe (PSP) launched in August 2018 is humanity's first probe of a stellar atmosphere. It will make measurements of the near-Sun plasma from 'within' the outer corona with gradually reduced perihelia from its first perihelia of 35 Rs in 2018-19 to 9.8 Rs in 2025. Here we report the results from the imaging observations of the electron and dust corona, whe PSP was 35-54 Rs from the solar surface, taken by the Wide-field Imager for Solar Probe (WISPR). The spacecraft was near-corotating with the solar corona throughout the observing window, which is an unprecedented situation for any type of coronal imaging. Our initial analysis uncovers a long-hypothesized depletion of the primordial dust orbiting near the Sun, reveals the plasma structure of small-scale ejections, and provides a strict test for validating model predictions of the large-scale configuration of the coronal plasma. Thus, WISPR imaging allows the study of near-Sun dust dynamics as the mission progresses. The high-resolution images of small transients, largely unresolved from 1 AU orbits, unravel the sub-structures of small magnetic flux ropes and show that the Sun continually releases helical magnetic fields in the background wind. Finally, WISPR's observations of the coronal streamer evolution confirm the large-scale topology of the solar corona but they also reveal that, as recently predicted, streamers are composed of yet smaller sub-streamers channeling continual density fluctuations at all visible scales. Title: Volume-filling Simulations of Coronal Loops Heated by Nanoflares Authors: Plowman, J.; Barnes, W.; Bradshaw, S. J.; Caspi, A.; DeForest, C.; Klimchuk, J. A. Bibcode: 2019AGUFMSH53B3380P Altcode: We present results of a coronal simulation consisting of loop strands that fill the coronal volume in a self-consistent fashion. The simulation is heated by a fully controllable 3D distribution, which can be specified independent of the loop geometry and can include nanoflares and continuous heating. The heating is then mapped to the loop strands, and the physics of each strand are simulated using the HYDRAD field-aligned hydrodynamics code. The simulation is applied to a small example active region and used to produce synthetic AIA data, which are then processed to produce a distribution of coronal EUV brightening events. This distribution is then compared with that found in the real AIA data for the same region, and we use the results to determine if the observations are consistent with our prescribed heating distribution. Title: Wide-Field Imager (WFI) for the Polarimeter to Unify the Corona and Heliosphere (PUNCH) Authors: Laurent, G. T.; DeForest, C.; Beasley, M.; Brownsberger, J.; Clapp, M.; Colaninno, R. C.; Howard, R. A.; McMullin, D. R.; Nagler, A.; Shoffner, M.; Smith, K. D.; Thernisien, A.; Waltham, N. Bibcode: 2019AGUFMSH41E3299L Altcode: The Wide-Field Imager (WFI) is one of three polarizing heliospheric imagers designed as part of Polarimeter to Unify the Corona and Heliosphere (PUNCH) to providing the first complete, photometric, high-resolution views of the corona/solar wind transition. The PUNCH payload also includes a Narrow-Field Imager (NFI) provided by The U.S. Naval Research Laboratory. Together, these instruments form a single "virtual instrument" covering the entire inner solar system continuously from 6 to 180 R⊙(1.5°-45° solar elongation, ɛ). Each instrument will be hosted on a 1+3 microsatellite constellation deployed into Sun-synchronous LEO. WFI implements a high heritage planar/corral hybrid baffle design to observe the inner heliosphere from 5°-45° in ɛ. As each WFI orbits Earth, it scans the entire range of solar azimuths once per orbit. WFI achieves the PUNCH required performance within the microsatellite mission concept with a high sunlight attenuation factor of 10-16 based on heritage designs of the STEREO/HI and SoloHI heliospheric imagers. SwRI has developed, tested, and environmentally qualified a WFI prototype instrument, confirming the expected performance of the baffle and optics as designed for PUNCH. Title: Combining Remote and in situ Parker Solar Probe and STEREO Data to Understand Solar Wind Density Structures Authors: Viall, N. M.; Howard, R. A.; Vourlidas, A.; DeForest, C.; Kasper, J. C.; Korreck, K. E.; Case, A. W.; Stevens, M. L.; Whittlesey, P. L.; Larson, D. E.; Livi, R.; Szabo, A.; Kepko, L.; Lavraud, B.; Rouillard, A. P.; Velli, M. Bibcode: 2019AGUFMSH13C3432V Altcode: The instrument suite on Parker Solar Probe offers an unprecedented viewpoint of the ambient solar wind and structure therein, shortly after its formation and release from the solar corona. We take advantage of the synergistic observations of the first Parker Solar Probe encounters and the STEREO COR2 deep field campaigns covering the same time periods to study mesoscale solar wind density structures. They often occur in a quasi-periodic train, especially near the heliospheric current sheet. Some may be a consequence of the development of dynamics en route; many are remnants of the formation and release of the solar wind, and provide important constraints on solar wind models. The opportunity to combine the different observing angles and fields of view of the white light WISPR observations and white light STEREO COR2 observations with in situ density and plasma measurements from SWEAP allows better understanding of the characteristics and properties of mesoscale density structures. The in situ data measure precise size scales, plasma boundaries, and relationships between density and other parameters. They help in the interpretation of the structures seen in white light images and in unraveling projection effects. The white light images enhance the in situ data by providing global heliospheric context, as well as the occurrence rate and 2-D size scales of structures as a function of latitude and distance from the Sun. Together, these observations provide crucial constraints on the formation of structures in the solar wind. Title: Flocculation, switchbacks, and loss of Alfvenicity: Indicators of shear-driven turbulence in the young solar wind? Authors: Matthaeus, W. H.; Ruffolo, D. J.; DeForest, C.; Parashar, T.; Goldstein, M. L.; Roberts, D. A.; Chhiber, R.; Usmanov, A. V.; Dudok de Wit, T.; Bandyopadhyay, R.; Chasapis, A.; Maruca, B.; Velli, M. C. M.; Kasper, J. C. Bibcode: 2019AGUFMSH53B3374M Altcode: Since the first preliminary announcements of Parker Solar Probe results [1], there has been increased discussion of "switchbacks" and speed enhancements such as those observed in Helios data [2]. A familiar explanation relies on outward propagation of large amplitude remnants of magnetic reconnection at lower altitudes. Such a mechanism is plausible and difficult to rule out. However, another possibility exists, namely that the onset of strong shear-driven turbulence, beginning just outside the Alfvén critical region, may induce the switchbacks through large-scale perturbation of the flow. This scenario is consistent with a suite of observable effects already apparent in imaging [3] and in situ datasets [2]. DeForest et al. interpreted the transition from elongated striae to relatively isotropic flocculae as a signature of the onset of shear-driven turbulent activity some 20-80 Rs from the photosphere, where the magnetic field ceases to be a dominant constraint on transverse motions; this interpretation has received support from turbulence-driven global simulations of the solar wind [4]. The presence of velocity shears is also strongly suggested by coronal imaging at lower altitudes [5]. Somewhere above the conventional Alfvén point such shears can begin supplying turbulence energy [6] while also destroying Alfvénicity by injection of kinetic energy but not cross helicity [7]. If indeed the flocculation signifies large fluctuations or even turnover associated with vortices, then specific features of shear driven turbulence may be anticipated in imaging data from the upcoming PUNCH mission and in ongoing analysis of in situ Parker Solar Probe observations. Details of these signatures will be given here. Research supported in part by grant RTA5980003 from the Thailand Research Fund, by NASA under NNX17AB79G, 80NSSC18K1210, 80NSSC18K1648, and by the PSP ISOIS project as subcontract under NNN06AA01C.

[1] S. Bale, invited talk, 2018 Fall AGU Meeting

[2] T. Horbury, L. Matteini & D. Stansby, MNRAS 478, 1980 (2018)

[3] C. DeForest et al., Astrophys. J. 828, 66 (2016)

[4] R. Chhiber et al., Astophys. J. Lett. 856, L39 (2018)

[5] C. DeForest et al., Astrophys. J. 862, 18 (2018)

[6] G. Zank et al., JGR 101, 17093 (1996); B. Breech et al., JGR 113, A08105 (2008)

[7] D. A. Roberts et al., JGR 97, 17115 (1992); see also Fig. 3 of D. A. Roberts, Astrophys. J. 711, 1044 (2010) Title: Near-Sun observations of an F-corona decrease and K-corona fine structure Authors: Howard, R. A.; Vourlidas, A.; Bothmer, V.; Colaninno, R. C.; DeForest, C. E.; Gallagher, B.; Hall, J. R.; Hess, P.; Higginson, A. K.; Korendyke, C. M.; Kouloumvakos, A.; Lamy, P. L.; Liewer, P. C.; Linker, J.; Linton, M.; Penteado, P.; Plunkett, S. P.; Poirier, N.; Raouafi, N. E.; Rich, N.; Rochus, P.; Rouillard, A. P.; Socker, D. G.; Stenborg, G.; Thernisien, A. F.; Viall, N. M. Bibcode: 2019Natur.576..232H Altcode: Remote observations of the solar photospheric light scattered by electrons (the K-corona) and dust (the F-corona or zodiacal light) have been made from the ground during eclipses1 and from space at distances as small as 0.3 astronomical units2-5 to the Sun. Previous observations6-8 of dust scattering have not confirmed the existence of the theoretically predicted dust-free zone near the Sun9-11. The transient nature of the corona has been well characterized for large events, but questions still remain (for example, about the initiation of the corona12 and the production of solar energetic particles13) and for small events even its structure is uncertain14. Here we report imaging of the solar corona15 during the first two perihelion passes (0.16-0.25 astronomical units) of the Parker Solar Probe spacecraft13, each lasting ten days. The view from these distances is qualitatively similar to the historical views from ground and space, but there are some notable differences. At short elongations, we observe a decrease in the intensity of the F-coronal intensity, which is suggestive of the long-sought dust free zone9-11. We also resolve the fine-scale plasma structure of very small eruptions, which are frequently ejected from the Sun. These take two forms: the frequently observed magnetic flux ropes12,16 and the predicted, but not yet observed, magnetic islands17,18 arising from the tearing-mode instability in the current sheet. Our observations of the coronal streamer evolution confirm the large-scale topology of the solar corona, but also reveal that, as recently predicted19, streamers are composed of yet smaller substreamers channelling continual density fluctuations at all visible scales. Title: PUNCH: a new view on the middle corona Authors: Gibson, S. E.; DeForest, C. Bibcode: 2019AGUFMSH13A..06G Altcode: The Polarimeter to UNify the Corona and Heliosphere (PUNCH) has recently been selected by NASA as a Small Explorer mission, to be launched as early as 2022. PUNCH uses a constellation of three wide-field heliospheric imagers and a central near-field coronagraphic imager to span the interface between the corona and the inner heliosphere. Polarized and unpolarized images will be obtained with greater than ten times the sensitivity of current instruments in the region covering 6-15 solar radii, i.e., the upper portion of the "middle corona". This will provide unprecedented views of the global structure of fast/slow wind flow boundaries, CME substructure and chirality, and the Alfven zone. This last is of particular interest to this session, because the riotous torrent that is the young solar wind implies the boundary between magnetically-dominated and wind-dominated plasma is likely to be fractal and space-filling. Thus, it is a zone that likely riddles the middle corona. Title: Modeling the Steady Solar Wind with an Observationally Driven Fluxon Coronal Magnetic Field Authors: Lowder, C.; Lamb, D. A.; DeForest, C. Bibcode: 2019AGUFMSH53B3398L Altcode: Here we describe the development of a flexible and efficient framework for a real-time capable solar wind predictive model. Our model allows for the isolation of geometric expansion in open magnetic fieldlines to explore the role of geometry in setting solar wind speed and density, distinct from other effects such as intermittent reconnection. The Field Line Universal relaXer (FLUX) code models the solar corona as a collection of magnetic domains, represented by a quasi-Lagrangian grid of discrete field lines (fluxons). Each fluxon represents a defined quantity of magnetic flux and responds to magnetic tension and pressure forces from neighboring fluxons. The model relaxes a collection of fluxons to solve the nonlinear force-free field with a prescribed boundary and topology. Synoptic magnetogram data are used to drive initial fluxon placement and topology, with the output of an observationally-driven relaxed coronal magnetic field. Open fluxons extending from the photospheric boundary are used to compute a set of modified one-dimensional isothermal Parker solar wind solutions, with transonic solutions interpolated to an outer spherical boundary grid at 21.5 solar radii for comparison with and distribution to other heliospheric models. The FLUX model has the distinct advantages of being computationally efficient (scaling with the complexity of the two-dimensional boundary) and preserving connectivity to allow for tracking the history of a bundle of magnetic flux. Title: Spectral Properties and Heavy Ion Abundances of Energetic Particles in SEP and CIR events observed during the first two Parker Solar Probe Orbits Authors: Desai, M. I.; Giacalone, J.; Mitchell, D. G.; Szalay, J. R.; Allen, R. C.; Hill, M. E.; McComas, D. J.; Christian, E. R.; Schwadron, N.; McNutt, R. L., Jr.; Wiedenbeck, M. E.; Joyce, C.; Cohen, C.; Cummings, A. C.; Davis, A.; Krimigis, S. M.; Leske, R. A.; Matthaeus, W. H.; Mewaldt, R. A.; Roelof, E. C.; Labrador, A. W.; Stone, E. C.; Gibson, S. E.; DeForest, C. Bibcode: 2019AGUFMSH22A..06D Altcode: NASA's Parker Solar Probe (PSP), successfully launched on August 12 2018, has completed its first two orbits around our Sun. With perihelia ~35 Rs for both encounters, PSP has made the closest-ever observations of the solar wind plasma, electromagnetic fields, and energetic particle environment in the inner heliosphere. The Energetic Particle Instruments (EPI) of the Integrated Science Investigation of the Sun (ISOIS) suite observed a number of solar energetic particle (SEP) events associated with flaring regions on the Sun, coronal mass ejections-driven shocks, and local compression regions, as well as particle events associated with corotating or stream interaction regions. This talk surveys the spectral properties and abundances of ~0.1-2 MeV/nucleon suprathermal H-Fe nuclei during these events and compares them with prior observations of their counterparts observed at 1 AU. We discuss these new PSP results in the context of our current understanding of the origin and acceleration of suprathermal ions, the acceleration of SEPs, and on the nature of particle transport inside Earth orbit. Finally, we discuss the implications of these results for existing theoretical models of the origin of suprathermal tails, and of the acceleration and transport of SEPs and CIR-associated energetic particle events. Title: The PUNCH Bowl: Data System and Data Products for NASA's PUNCH Mission Authors: Thompson, B. J.; DeForest, C.; Gibson, S. E. Bibcode: 2019AGUFMSA11C3231T Altcode: The Polarimeter to UNify the Corona and Heliosphere (PUNCH) mission requires a flexible data system because the anticipated user base will be using the data to tackle a wide range of science problems. Some will be using PUNCH data in the classic "imager" context, while others will be accessing the data to study solar wind dynamics.

The PUNCH Bowl provide PUNCH data, metadata, analysis tools, and higher-level PUNCH data products, which are derived from heliospheric images to provide additional information about structure and motion. Additionally, the PUNCH Bowl is your access point for PUNCH Recipes: all of the tools, code and routines that optimize the use of PUNCH data and streamline your access. By running the "recipes" users can easily trace and reproduce the steps used by others with minimal effort. The PUNCH Bowl is maintained and supported by the PUNCH science team, but welcomes contributions from users to ensure that everyone is able to easily access all available tools and methods. Title: Novel observations of the middle corona during the 2017 total solar eclipse Authors: Caspi, A.; Seaton, D. B.; Tsang, C.; DeForest, C.; Bryans, P.; Samra, J.; DeLuca, E.; Tomczyk, S.; Burkepile, J.; Gallagher, P.; Golub, L.; Judge, P. G.; Laurent, G. T.; West, M.; Zhukov, A. Bibcode: 2019AGUFMSH13A..10C Altcode: Total solar eclipses offer rare opportunities to study the middle corona. This intriguing region contains complex interfaces and transitions between physical regimes, but has historically been under-observed due to the challenges of observing its dim emission so close to the bright inner corona and blinding solar disk. The unique circumstances of a total solar eclipse coupled with a high-altitude observing platform provide nearly space-quality observing conditions, including for wavelengths inaccessible by ground-based observatories, but with availability of ground-quality resources, including high-speed, high-resolution, wide-field coronography typically inaccessible from space. We used the 2017 August 21 "Great American" total solar eclipse to observe the solar corona from ~1.02 to ~3 RSun in both visible (533.9 ± 4.75 nm) and medium-wave infrared (3-5 μm) light using stabilized telescopes on two of NASA's WB-57F high-altitude research aircraft. This pathfinding mission utilized existing instrumentation to evaluate the platform performance, guide instrumentation development, and explore new discovery space for future studies of the middle corona.

We present the high-speed (30 Hz), high-resolution (3 arcsec/pixel) visible and IR observations obtained during the eclipse, and analysis of these observations in the context of coronal structure and dynamics. We discuss the limitations of the prototype data and pathways forward for future instrumentation and missions optimized for the range of observable parameters in the middle corona. We also discuss the benefits of such eclipse studies to an understanding of the corona as a single, unified system, from its origins at the solar surface to its extension into the heliosphere, particularly within the context of a developing multi- and inter-disciplinary research collaboration, COHERENT (the "Corona as a Holistic Environment" Research Network). Title: Polarimeter to UNify the Corona and Heliosphere (PUNCH): Imaging the Corona and Solar Wind as a Single System Authors: DeForest, C. E.; Gibson, S. E.; Beasley, M.; Colaninno, R. C.; Killough, R.; Kosmann, W.; Laurent, G. T.; McMullin, D. R. Bibcode: 2019AGUFMSH43B..06D Altcode: The Polarimeter to UNify the Corona and Heliosphere (PUNCH) is a Small Explorer mission from NASA, to understand the solar corona and young solar wind as a complete system. It comprises four matched cameras all operating as a "virtual instrument" to image Thomson-scattered light, from the vantage of four separate spacecraft in Sun-synchronous LEO. PUNCH is the first coronal and solar wind imager designed specifically to produce three dimensional images from a single vantage point. In addition, it will produce routine, several-times-per-day maps of solar wind flow throughout the outer corona and inner heliosphere, based on motion analysis of the image stream. Estimated launch date is early 2023 for a two-year nominal mission. We present a brief overview of the mission with emphasis on novel techniques used and exploited by the PUNCH mission, and novel analyses enabled for the science community by PUNCH. Title: Improving Forecast Lead Times for the Solar Wind, IMF, and Kp Index Authors: Elliott, H. A.; Arge, C. N.; Henney, C. J.; DeForest, C.; McComas, D. J.; Jahn, J. M.; Dayeh, M. A.; Lepri, S. T.; Azeem, S. I.; Crowley, G. Bibcode: 2019AGUFMSH32B..02E Altcode: Solar wind and Interplanetary Magnetic Field (IMF) observations near Earth now span several solar cycles; however, this information has not been fully leveraged to improve forecasts. We test the ability to produce forecast with lead times of 3-4 days for such parameters as the Kp index; the solar wind density, speed and temperature; and the IMF magnitude and vector components in GSM (Bx, By, and Bz) parameters. To do so we utilize the statistical relationships amongst combinations of these parameters. We apply these relationships to forecasts of the solar wind speed and radial magnetic field from the combined Air Force Data Assimilative Photospheric Flux Transport (ADAPT) and Wang-Sheeley-Arge (WSA) models. The WSA model produces some of the most accurate solar wind speed forecasts based on solar observations using two empirical relationships: 1) the relationship between the solar wind speed and magnetic field expansion factor, and 2) the relationship between solar wind speed and the minimum angular distance between the footpoint and open-closed field line boundary. The solar wind and IMF parameters reflect a combination of solar source properties and changes that occur en route owing to dynamic interactions between the fast and slow wind. We develop relationships that distinguish contributions from the solar sources versus those from dynamic interactions. We use the strength of the rise and fall of the solar wind speed profile to isolate the impact of dynamic interactions on the relationships between solar wind and IMF parameters. Additionally, we test removing long term trends in the solar wind and IMF parameters owing to changes in the solar source properties by developing relationships normalized by an average value from the prior solar rotation. We demonstrate that contributions from the source and dynamic interactions present in the solar wind and IMF can also be harnessed to produce long term (3-4 day) Kp forecasts. These relationships serve as individual metrics for physical models, and when combined the relationships provide a comprehensive baseline empirical model of the solar wind, IMF, and Kp index. Title: Spectroscopic Constraints on the Cross-sectional Asymmetry and Expansion of Active Region Loops Authors: Kucera, T. A.; Young, P. R.; Klimchuk, J. A.; DeForest, C. E. Bibcode: 2019ApJ...885....7K Altcode: We explore the constraints that can be placed on the dimensions of coronal loops out of the plane of the sky by utilizing spectroscopic observations from the Hinode/EUV Imaging Spectrometer (EIS). The usual assumption is that loop cross sections are circular. Changes in intensity are assumed to be the result of changing density, filling factor, and/or point of view. In this work we instead focus on the possibility that the loop dimensions may be changing along the line of sight while the filling factor remains constant. We apply these ideas to two warm (5.5≲ {log}T({{K}})< 6.2) loops observed by EIS in Active Region 11150 on 2011 February 6 with supporting observations from Solar Dynamics Observatory's Atmospheric Imaging Assembly and the Solar TErrestrial RElations Observatory-A's Extreme Ultraviolet Imager. Our results are generally consistent with nonexpanding loops but could also allow linear expansions of up to a factor of 2.5 along a 40 Mm section of one loop and up to a factor of 3.9 in another loop, both under the assumption that the filling factor is constant along the loop. Expansions in the plane of the sky over the same sections of the loops are 1.5 or less. For a filling factor of 1, the results of the analysis are consistent with circular cross sections but also with aspect ratios of 2 or greater. Count rate statistics are an important part of the uncertainties, but the results are also significantly dependent on radiometric calibration of EIS and the selection of the loop backgrounds. Title: Constraints from Hinode/EIS on the Expansion of Active Region Loops Along the Line of Sight Authors: Kucera, Therese A.; Young, Peter R.; Klimchuk, James A.; DeForest, Craig Bibcode: 2019AAS...23411706K Altcode: We explore the constraints that can be placed on the dimensions of coronal loops out of the plane of the sky by utilizing spectroscopic observations from the Hinode/EUV Imaging Spectrometer (EIS). The usual assumption is that loop cross sections are circular. Changes in intensity not constant with the measured width are assumed to be the result of changing density and/or filling factor. Here we instead focus on the possibility that the loop dimensions may be changing along the line of sight while the filling factor remains constant. We apply these ideas to two cool (5.5<logT<6.2) loops observed by EIS with supporting observations from Solar Dynamics Observatory's Atmospheric Imaging Assembly (SDO/AIA) and the Solar TErrestrial RElations Observatory-A's Extreme Ultraviolet Imager (STEREO-A/EUVI). Our results are generally consistent with non-expanding loops, but allow for line-of-sight expansion factors up to 3-4. The uncertainties are sizable and are driven by count rate statistics, radiometric calibration of EIS, and the selection of the loop backgrounds. Title: Fluxon Modeling of CMEs and the Steady Solar Wind Authors: Lowder, Chris; Lamb, Derek; DeForest, Craig Bibcode: 2019AAS...23412503L Altcode: The Field Line Universal relaXer (FLUX) code provides a framework for modeling the evolution of the solar coronal magnetic field through the use of fluxon structures. Each fluxon represents a piecewise-linear analogue for magnetic field lines, and carries a finite quantity of magnetic flux. Appropriate forces are computed and applied at vertex points along each fluxon, allowing for relaxation to an equilibrium state. For a given initial configuration, this allows for the study of fieldline topology and subsequent evolution. The nature of the FLUX model allows for enhanced efficiency when compared with grid-based MHD models, and avoids numerical reconnection issues. We describe recent enhancements to the FLUX code, including work with data assimilation, calculation of steady solar wind solutions, and CME eruption triggering. Title: Denoising off-disk regions for solar knowledge discovery Authors: Hughes, James Marcus; Monteleoni, Claire; Seaton, Daniel B.; Bain, Hazel M.; DeForest, Craig Bibcode: 2019shin.confE.124H Altcode: Machine learning methods offer great promise for image processing in solar physics. We compare methods of denoising solar EUV images with an emphasis on reconstructing low signal-to-noise off-disk regions. These regions are home to the transition corona, where plasma beta goes from low (magnetically dominated) to high (gas pressure dominated), magnetic field topology goes from mostly closed to mostly open, and the solar wind transitions from subsonic to supersonic. New observations of this region could help us develop a more robust understanding of the Sun-Heliosphere connection. Our work compares existing solar approaches to machine learning techniques. Since we do not have noise-free images to learn from, we employ an approach similar to Noise2Self, with the addition of temporal and spectral information available in the solar domain. With these new cleaned images, we perform image segmentation to produce thematic maps, images of the Sun where different structures such as coronal holes and active regions are identified, and test anomaly detection algorithms with the goal of automating discovery of scientifically interesting events. Title: COHERENT: Studying the corona as a holistic environment Authors: Caspi, Amir; Seaton, Daniel B.; Case, Traci; Cheung, Mark; Cranmer, Steven; DeForest, Craig E.; de Toma, Giuliana; Downs, Cooper; Elliott, Heather; Gold, Anne U.; Longcope, Dana; Savage, Sabrina L.; Sullivan, Susan; Viall, Nicholeen; Vourlidas, Angelos; West, Matthew J. Bibcode: 2019shin.confE.241C Altcode: The solar corona and the heliosphere must be part of a single physical system, but because the dominant physical processes change dramatically from the magnetically-dominated low corona, through the sparsely-observed middle corona, and into the plasma flow-dominated outer corona and heliospheric interface, unified frameworks to study the corona as a whole are essentially nonexistent. Understanding how physical processes shape and drive the dynamics of the corona as a global system, on all spatiotemporal scales, is critical for solving many fundamental problems in solar and heliospheric physics. However, the lack of unifying observations and models has led to a fragmentation of the community into distinct regimes of plasma parameter space, largely clustering around regions where existing instrumentation has made observations widely available and where models can be sufficiently self-contained to be tractable. We describe COHERENT, the 'Corona as a Holistic Environment' Research Network, a focused effort to facilitate interdisciplinary collaborative research to develop frameworks for unifying existing and upcoming observations, theory, models, and analytical tools to study the corona as a holistic system. Title: Modeling the Steady Solar Wind with Observationally Driven Fluxons Authors: Lowder, Chris; Lamb, Derek; DeForest, Craig Bibcode: 2019shin.confE.155L Altcode: The Field Line Universal relaXer (FLUX) code models the solar corona as a collection of discrete analogue magnetic domains, via a quasi-Lagrangian grid of discrete field lines - fluxons. Each fluxon carries a defined quantity of magnetic flux and responds to magnetic tension and pressure forces from neighboring fluxons, relaxing to a nonlinear force-free field in an equilibrium state. The FLUX model scales computationally with the complexity of the two-dimensional simulation boundary and avoids simulation grid issues, providing an efficient tool for coronal field modeling. Assimilation of synoptic magnetogram data drives fluxon placement, providing a relaxed coronal field configuration out to 21.5 solar radii. Topologically open fluxons are used to compute a set of modified isothermal Parker solar wind solutions, which are then interpolated onto an outer spherical boundary grid for comparison or input to solar wind models. The FLUX model provides a flexible and efficient framework for modeling of the coronal magnetic field and the steady solar wind. Title: Multiwavelength Study of Equatorial Coronal-hole Jets Authors: Kumar, Pankaj; Karpen, Judith T.; Antiochos, Spiro K.; Wyper, Peter F.; DeVore, C. Richard; DeForest, Craig E. Bibcode: 2019ApJ...873...93K Altcode: 2019arXiv190200922K Jets (transient/collimated plasma ejections) occur frequently throughout the solar corona and contribute mass/energy to the corona and solar wind. By combining numerical simulations and high-resolution observations, we have made substantial progress recently on determining the energy buildup and release processes in these jets. Here we describe a study of 27 equatorial coronal-hole jets using Solar Dynamics Observatory/Atmospheric Imaging Assembly and Helioseismic and Magnetic Imager observations on 2013 June 27-28 and 2014 January 8-10. Out of 27 jets, 18 (67%) are associated with mini-filament ejections; the other nine (33%) do not show mini-filament eruptions but do exhibit mini-flare arcades and other eruptive signatures. This indicates that every jet in our sample involved a filament-channel eruption. From the complete set of events, six jets (22%) are apparently associated with tiny flux-cancellation events at the polarity inversion line, and two jets (7%) are associated with sympathetic eruptions of filaments from neighboring bright points. Potential-field extrapolations of the source-region photospheric magnetic fields reveal that all jets originated in the fan-spine topology of an embedded bipole associated with an extreme ultraviolet coronal bright point. Hence, all our jets are in agreement with the breakout model of solar eruptions. We present selected examples and discuss the implications for the jet energy buildup and initiation mechanisms. Title: New solar diagnostics enabled by novel soft x-ray imaging spectroscopy, and future missions Authors: Caspi, Amir; Sylwester, Janusz; Gburek, Szymon; Crowley, Geoff; Woods, Thomas; Shih, Albert Y.; DeForest, Craig; Steslicki, Marek; Warren, Harry; Mason, James Bibcode: 2018cosp...42E.525C Altcode: Solar soft X-ray (SXR) observations provide unique diagnostics of plasma heating, during solar flares and quiescent times. Spectrally- and temporally-resolved measurements are crucial for understanding the dynamics and evolution of these energetic processes; spatially-resolved measurements are essential for understanding energy transport. A critical observational gap exists from ∼0.2 to ∼3 keV (∼4-60 Å), where spectrally-resolved stellar observations are plentiful but have not been routinely made for the Sun in many decades. This energy range includes spectral lines from highly-ionized atoms with both low and high first ionization potential (FIP), as well as thermal free-free (bremsstrahlung) and free-bound (radiative recombination) continua. These SXR emissions provide crucial diagnostics of plasma temperature distributions, as well as elemental abundances that probe plasma origins over a wide range of temperatures, that are not available from observations at other wavelengths. A better understanding of thermal plasma also informs our interpretation of hard X-ray (HXR) observations of nonthermal particles, improving our understanding of the relationships between particle acceleration, plasma heating, and the underlying release of magnetic energy during reconnection.We discuss a proposed small satellite pathfinder mission, the CubeSat Imaging X-ray Solar Spectrometer (CubIXSS), to measure spectrally- and spatially-resolved SXRs from the quiescent and flaring Sun from a 6U CubeSat platform in low-Earth orbit during a nominal 1-year mission. CubIXSS includes the Amptek X123-FastSDD silicon drift detector, a low-noise, commercial off-the-shelf (COTS) instrument enabling full-Sun SXR spectroscopy from ∼0.5 to ∼20 keV with ∼0.15 keV FWHM spectral resolution with low power, mass, and volume requirements. Multiple detectors and tailored apertures provide sensitivity to SXR emission from deep solar minimum to >X5 flares. An X123-CdTe cadmium-telluride detector is also included for ∼5-50 keV HXR spectroscopy with ∼0.5 keV FWHM resolution. The precise spectra from these instruments will provide detailed measurements of the coronal temperature distribution and elemental abundances during flares and quiescent times, and, for large flares, context information of flare-accelerated electrons.CubIXSS also includes a novel spectro-spatial imager - the first ever solar imager on a CubeSat - utilizing a custom pinhole camera and Chandra-heritage X-ray transmission diffraction grating to provide spatially- resolved, full-Sun imaging spectroscopy from ∼0.2 to ∼10 keV (∼1-60 Å), with ∼25 arcsec and ∼0.25 Å FWHM spatial and spectral resolutions, respectively. Additional pinholes with tailored filters provide non-dispersed images with coarse spectral information to seed analysis of the dispersed spectro-spatial images and for improved sensitivity to quiescent conditions. MOXSI's unique capabilities enable SXR spectroscopy and corresponding temperature and elemental abundance diagnostics of individual flares and active regions over a spectral range never before accessed by any prior solar mission.CubIXSS is a pathfinder for larger satellites with improved resolution and sensitivity. Through these groundbreaking new measurements, CubIXSS and future missions will improve our physical understanding of thermal plasma processes and impulsive energy release in the solar corona, from quiet Sun to solar flares. Title: Tracing the Origins of the Solar Wind by Tracking Flows and Disturbances in Coronagraph Data Authors: Thompson, Barbara J.; Attie, Raphael; DeForest, Craig E.; Gibson, Sarah E.; Hess Webber, Shea A.; Ireland, Jack; Kirk, Michael S. F.; Kwon, Ryun Young; McGranaghan, Ryan; Viall, Nicholeen M. Bibcode: 2018shin.confE..47T Altcode: The challenge of identifying transient motions in solar imagery has been addressed in a number of ways. A variety of methods have been developed to detect and characterize the motion and extent of coronal mass ejections, for example. We discuss the adaptation of CME and solar transient detection methods to trace smaller-scale perturbations consistent with solar wind motions in the inner heliosphere (out to 10 RSun). We evaluate several methods, and compare the speed and structure results to model predictions. In particular, we discuss how high-cadence heliospheric imagery can be used to track small scale solar density variations throughout the solar wind, serving as a proxy for in situ velocity detection, but with global and continuous coverage. Title: Using Polarized White Light Triplets Measured by STEREO to Isolate Internal Structure Authors: de Koning, Curt A.; DeForest, Craig E. Bibcode: 2018shin.confE.199D Altcode: On 2010 April 3, the SECCHI/COR2 coronagraphs on board the twin NASA/STEREO spacecraft observed a coronal mass ejection (CME) in total and polarized brightness white light. It has been suggested that exploiting the full range of white light imagery, including the polarization ratio, may enable reconstruction of CME internal features as well as CME morphology; however, noisy imagery has made this promise difficult to fulfill. Using a recently developed noise-gating process to improve the signal-to-noise ratio in COR2, we demonstrate that we can spatially isolate features within the CME. Title: The Highly Structured Outer Solar Corona Authors: DeForest, C. E.; Howard, R. A.; Velli, M.; Viall, N.; Vourlidas, A. Bibcode: 2018ApJ...862...18D Altcode: We report on the observation of fine-scale structure in the outer corona at solar maximum, using deep-exposure campaign data from the Solar Terrestrial Relations Observatory-A (STEREO-A)/COR2 coronagraph coupled with postprocessing to further reduce noise and thereby improve effective spatial resolution. The processed images reveal radial structure with high density contrast at all observable scales down to the optical limit of the instrument, giving the corona a “woodgrain” appearance. Inferred density varies by an order of magnitude on spatial scales of 50 Mm and follows an f -1 spatial spectrum. The variations belie the notion of a smooth outer corona. They are inconsistent with a well-defined “Alfvén surface,” indicating instead a more nuanced “Alfvén zone”—a broad trans-Alfvénic region rather than a simple boundary. Intermittent compact structures are also present at all observable scales, forming a size spectrum with the familiar “Sheeley blobs” at the large-scale end. We use these structures to track overall flow and acceleration, finding that it is highly inhomogeneous and accelerates gradually out to the limit of the COR2 field of view. Lagged autocorrelation of the corona has an enigmatic dip around 10 R ⊙, perhaps pointing to new phenomena near this altitude. These results point toward a highly complex outer corona with far more structure and local dynamics than has been apparent. We discuss the impact of these results on solar and solar-wind physics and what future studies and measurements are necessary to build upon them. Title: New Coronal Science from NASA WB-57F High-Altitude Aircraft Observations of the 2017 Total Solar Eclipse Authors: Caspi, Amir; DeLuca, . Edward; Tomczyk, Steven; DeForest, Craig; Bryans, Paul; Seaton, Daniel; Tsang, Constantine Bibcode: 2018cosp...42E.526C Altcode: Total solar eclipses present rare opportunities to study the complex solar corona, down to altitudes of just a few percent of a solar radius above the surface, using ground-based and airborne observatories that would otherwise be dominated by the intense solar disk and high sky brightness. Studying the corona is critical to gaining a better understanding of physical processes that occur on other stars and astrophysical objects, as well as understanding the dominant driver of space weather that affects human assets at Earth and elsewhere. For example, it is still poorly understood how the corona is heated to temperatures of 1-2 MK globally and up to 5-10 MK above active regions, while the underlying chromosphere is 100 times cooler; numerous theories abound, but are difficult to constrain due to the limited sensitivities and cadences of prior measurements. The stability of large-scale coronal structures and the extent of their reach to the middle and outer corona are also not well known, limited in large part by sensitivities and fields of view of existing observations.Airborne observations during a total eclipse provide unique advantages. By flying in the stratosphere at altitudes of 50 kft or higher, they avoid all weather, the seeing quality is enormously improved, and additional wavelengths such as near-IR also become available due to significantly reduced water absorption. An airborne observatory can also follow the Moon's shadow, increasing the total observing time by 50% or more.We present current results of solar coronal measurements from airborne observations of the 2017 Great American Total Solar Eclipse using two of NASA's WB-57 high-altitude research aircraft, each equipped with two 8.7" telescopes feeding high-sensitivity visible (green line and nearby continuum) and medium-wave IR (3-5 {μ}m) cameras operating at high cadence (30 Hz) with ∼3 arcsec/pixel platescale and ±3 R_{sun} fields of view. The aircraft flew along the eclipse path, separated by ∼110 km, to observe a summed ∼7.5 minutes of totality in both visible and MWIR. These observations enable groundbreaking studies of high-speed coherent motion - including possible Alfvén waves and nanojets - in the lower and middle corona that could shed light on coronal heating processes and the formation and stability of coronal structures. Our MWIR observations of a cool prominence and hot coronal active region plasma will be combined with spectra from the AIR-Spec instrument, flown concurrently on NCAR's HIAPER GV. We review the WB-57 eclipse mission and the current results of analysis on the visible and IR coronal measurements, along with an outlook for future analysis and missions. Title: Characterizing Coronal Structure: Contextual Predictions For Parker Solar Probe From Global MHD Simulations With Dynamical Turbulence Modeling Authors: Chhiber, Rohit; Goldstein, Mevlyn; Matthaeus, William; Usmanov, Arcadi; Parashar, Tulasi; DeForest, Craig Bibcode: 2018cosp...42E.628C Altcode: As the solar plasma flows out from the corona and transitions into the solar wind, it transforms from a magnetically structured, subsonic, and sub-Alfvénic regime into a supersonic and super-Alfvénic flow dominated by hydrodynamics. Recent analysis of remote imaging observations in solar minimum conditions by DeForest et al. (2016) has described the early stages of this transition, which may also coincide with the onset of large-scale turbulence in the solar wind. Here we extend this analysis to global magnetohydrodynamic simulation of the corona and solar wind based on inner boundary conditions that emulate solar minimum, in anticipation of the first phase of Parker Solar Probe (PSP) observations, which are expected during solar minimum as well. Taken together with the imaging analysis, the simulation results provide more detailed expectations for locations of the Alfvén critical surface and the first plasma beta unity surface moving from the corona into the dynamically active solar wind. The turbulence parameters computed from the simulations also enable estimations of the characteristic scales at which in-situ turbulence may influence the dynamics of the solar wind. Estimations of relevant parameters along a simulated PSP trajectory are presented. Issues pertaining to the use of Taylor's frozen-in hypothesis with PSP perihelion data are discussed. Title: Multiwavelength Study of 24 Equatorial Coronal-Hole Jets Authors: Kumar, Pankaj; Antiochos, Spiro; Karpen, Judy; DeForest, Craig; DeVore, C. Richard; Wyper, Peter Bibcode: 2018cosp...42E1863K Altcode: We studied 24 equatorial coronal-hole (ECH) jets using SDO/AIA and HMI observations on 27-28 June 2013 and 8-10 January 2014. Out of 24 jets (i) 16 jets (67%) are associated with mini-filament eruptions; (ii) 8 jets (34%) are triggered without mini-filament eruptions but with mini-flare arcades and other CME-like signatures; (iii) 5 jets (21%) are apparently associated with tiny flux-cancellation events at the polarity inversion line; (iv) 3 events are associated with sympathetic eruptions of filaments from neighboring jet source regions. The potential field extrapolations of the source regions reveal that almost all jets occurred in the fan-spine topology, and most of the events are in agreement with the breakout model of solar jets. We will present selected examples of each type, and discuss the implications for the jet energy-buildup and initiation mechanisms. Title: Tracking Flows and Disturbances in Coronagraph Data Authors: Thompson, Barbara J.; Attie, Raphael; DeForest, Craig E.; Gibson, Sarah E.; Hess Webber, Shea A.; Inglis, Anfew R.; Ireland, Jack; Kirk, Michael S.; Kwon, RyunYoung; Viall, Nicholeen M. Bibcode: 2018tess.conf30922T Altcode: The challenge of identifying transient motions in solar imagery has been addressed in a number of ways. A variety of methods have been developed to detect and characterize the motion and extent of coronal mass ejections, for example. We discuss the adaptation of CME and solar transient detection methods to trace smaller-scale perturbations consistent with solar wind motions in the inner heliosphere (over 10 RSun). We evaluate several methods, and compare the speed and structure results to model predictions. In particular, we discuss how high-cadence heliospheric imagery can be used to track small scale solar density variations throughout the solar wind, serving as a proxy for in situ velocity detection, but with global and continuous coverage. Title: Turtles All The Way Down: The finely structured outer corona, and its implications for PSP Authors: DeForest, Craig E.; Howard, Russell A.; Velli, Marco C. M.; Viall, Nicholeen M.; Vourlidas, Angelos Bibcode: 2018tess.conf30928D Altcode: Based on optical resolution of the starfield with SOHO/LASCO, STEREO/COR, and other coronagraphs, there is widespread intuition that the solar corona becomes more smooth with altitude. This is an optical illusion, caused by the interplay between signal-to-noise ratio (SNR) and feature size in typical coronal images. Processed, low-noise, deep-field COR2 images of the outer corona reveal rich structure at all observable scales, with surprising time variability and very short spatial correlation scales under 50 Mm, at altitudes near 10 Rs. This has deep implications not only for the solar wind and outer coronal physics, but also for the types of structure that Parker Solar Probe will encounter. We will present and discuss the fundamental result, and explore its implications for in-situ science and required context imaging from PSP. We will also make specific predictions about the environment PSP will encounter at solar altitudes of 10-15 Rs. Title: Eclipse Science from 50,000 Feet: New Coronal Results from NASA WB-57F High-Altitude Aircraft Observations of the 2017 Total Solar Eclipse Authors: Caspi, Amir; Tsang, Constantine; Seaton, Daniel B.; DeForest, Craig; Bryans, Paul; DeLuca, Edward; Tomczyk, Steven; Burkepile, Joan; Casey, Thomas Anthony; Collier, John; Darrow, Donald DD; Del Rosso, Dominic; Durda, Daniel D.; Gallagher, Peter; Gascar, Jasmine; Golub, Leon; Jacyna, Matthew; Johnson, David DJ; Judge, Philip G.; Klemm, Cary; Laurent, Glenn Thomas; Lewis, Johanna; Mallini, Charles; Parent, Thomas Duster; Propp, Timothy; Steffl, Andrew; Warner, Jeff; West, Matthew John; Wiseman, John; Yates, Mallory; Zhukov, Andrei Bibcode: 2018tess.conf31302C Altcode: Total solar eclipses present rare opportunities to study the complex solar corona, down to altitudes of just a few percent of a solar radius above the surface. Studying the corona is critical to gaining a better understanding of the dominant driver of space weather that affects human assets on Earth and elsewhere. For example, it is still poorly understood how the corona is heated to temperatures of 1-2 MK globally and up to 5-10 MK above active regions, while the underlying chromosphere is 100 times cooler. The stability of large-scale coronal structures and the extent of their reach to the middle and outer corona are also not well known, limited in large part by sensitivities and fields of view of existing observations.

Airborne observations during a total eclipse provide unique advantages. By flying in the stratosphere at altitudes of 50 kft or higher, they avoid all weather, the seeing quality is enormously improved, and additional wavelengths such as near-IR also become available due to significantly reduced water absorption. An airborne observatory can also follow the Moon's shadow, increasing the total observing time by 50% or more.

We present current results of solar coronal measurements from airborne observations of the 2017 Great American Total Solar Eclipse using two of NASA's WB-57 high-altitude research aircraft, each equipped with two 8.7-inch telescopes feeding high-sensitivity visible (green line and nearby continuum) and medium-wave IR (3-5 μm) cameras operating at high cadence (30 Hz) with ∼3 arcsec/pixel platescale and ±3 Rsun fields of view. The two aircraft flew along the eclipse path, separated by ∼110 km, to observe a total of ∼7.5 minutes of totality in both visible and MWIR. These observations enable groundbreaking studies of high-speed coherent motion - including possible Alfvén waves and nanojets - in the lower and middle corona that could shed light on coronal heating processes and the formation and stability of coronal structures. Our MWIR observations of a cool prominence and hot coronal active region plasma will be combined with spectra from the AIR-Spec instrument, flown concurrently on NCAR's HIAPER GV. We review the WB-57 eclipse mission and the current results of analysis on the visible and IR coronal measurements, along with an outlook for future analysis and missions. Title: Statistical Study of 24 Equatorial Coronal-Hole Jets Authors: Kumar, Pankaj; Karpen, Judith T.; Antiochos, Spiro K.; Fraser Wyper, Peter; DeVore, C. Richard; DeForest, Craig Bibcode: 2018tess.conf40805K Altcode: To understand the trigger mechanisms of coronal-hole jets, we analysed 24 equatorial coronal-hole (ECH) jets using SDO/AIA and HMI observations during 2013-2014. Out of 24 jets (i) 16 jets (67%) are associated with mini-filament eruptions; (ii) 8 jets (34%) are triggered without mini-filament eruptions but with mini-flare arcades and other CME-like signatures; (iii) 5 jets (21%) are apparently associated with tiny flux-cancellation events at the polarity inversion line; (iv) 3 events are associated with sympathetic eruptions of filaments from neighboring jet source regions. The potential field extrapolations of the source regions reveal that almost all jets occurred in the fan-spine topology, and most of the events are in agreement with the breakout model of solar jets. We will present selected examples of each type, and discuss the implications for the jet energy-buildup and initiation mechanisms. Title: Unifying the Solar Corona and Heliosphere Authors: DeForest, Craig E. Bibcode: 2018tess.conf31701D Altcode: The corona and solar wind are parts of a single unified system.

For at least five decades, solar coronal physics and solar wind physics have been divided by the instrumentation that each field uses to study essentially the same plasma. Solar wind studies have used primarily in situ sampling such as local measurement of magnetic field, solar wind parameters, and compisition, which reveal great detail and physical "ground truth" over a tiny cross-section of the solar wind. Solar coronal studies have used primarily remote imaging such as coronagraphic movies, which reveal large-scale evolution and structure, at a cost of limiting measurements to (in most cases) a photometric measure of the line-of-sight electron density. Recent advances in in-situ sampling (the development of \emph{Parker Solar Probe} and revisitation of data from the \emph{Helios} mission) enable direct sampling of the corona using the technology formerly applied to the solar wind. In parallel, advances in high-sensitivity imaging have permitted direct imaging of the solar wind itself as it forms.

I will recap the state of high sensitivity coronal imaging, which demonstrates that the phenomenology and dynamics of the outer corona (and its transition to the solar wind) are every bit as rich as the dynamics of the inner corona. Developing a fully unified understanding of this region requires not only direct sampling of the microphysics by Parker Solar Probe, but also remote measurement of the cross-scale physics of this turbulent, complex interface between the star and its environs. This understanding is central both to scientific understanding of the heliosphere, and also to improving space weather prediction, because the largest source of uncertainty in space weather at Earth is the environment through which CMEs and other disturbances propagate. Deep-field, polarized imaging of the outer corona and young solar wind are technically feasible and will reveal the "missing link" of the young solar wind, in its full global and cross-scale complexity. Title: Towards Fluxon Modeling of CMEs and the Steady Solar Wind Authors: Lowder, Chris; Lamb, Derek A.; DeForest, Craig Bibcode: 2018tess.conf10416L Altcode: The Field Line Universal relaXer (FLUX) code provides a framework for modeling MHD evolution in the solar corona. 'Fluxons' are the piecewise-linear analogue for magnetic field lines, composed of segments connecting individual vertices. Each fluxon carries a finite quantity of magnetic flux. Within the simulation, forces are calculated and applied to vertex points, relaxing to an equilibrium state. With physical quantities only defined along the fluxons, interpolation is required for calculating plasma parameters at arbitrary locations, or for interfacing with grid-based simulations. We describe recent changes to this interpolation code that result in improved interpolation results with minimal impact on computational cost. With these modifications, FLUX is a more robust tool for solar wind modeling and studying the magnetic structure of solar coronal eruptions. Title: Using Global Simulations to make Contextual Predictions for Parker Solar Probe: Critical Surfaces and Turbulence Authors: Chhiber, Rohit; Usmanov, Arcadi V.; Matthaeus, William H.; Parashar, Tulasi; Goldstein, Melvyn L.; DeForest, Craig Bibcode: 2018tess.conf31203C Altcode: The Parker Solar Probe (PSP) mission is scheduled for a summer 2018 launch, with the goal of exploring regions of the solar wind that are of crucial importance in establishing the heliosphere. The spacecraft will approach the Sun closer than any prior mission has, and will present unique and unprecedented opportunities to characterize the physical properties of the solar corona. As the PSP makes its high-resolution in-situ measurements, a knowledge of the large-scale environment of these observations will be of vital importance. In particular, one would like to have an indication of the locations of the critical surfaces that characterize the transformation of the coronal plasma from a magnetically structured, subsonic, and sub-Alfvénic regime into a supersonic and super-Alfvénic flow dominated by hydrodynamics. These surfaces - the sonic surface, the Alfvén surface, and the first plasma beta unity surface - may be associated with several phenomena of interest to PSP science, ranging from preferential heating of alpha particles to the onset of large-scale turbulence. Here we present results from global three-dimensional magnetohydrodynamic (MHD) simulations of the solar wind that we have used to localize the critical surfaces and investigate the flow in propinquitous regions. Effects of solar activity are incorporated by varying source magnetic dipole tilts and by employing magnetogram-based boundary conditions. A small-scale MHD turbulence model is self-consistently and dynamically coupled to the bulk flow equations, enabling investigation of turbulence properties of the flow in the vicinity of critical regions. The simulation results are compared with a variety of remote sensing observations. A simulated PSP trajectory is used to provide contextual predictions for the spacecraft in terms of the computed critical surfaces. We also examine the turbulence environment the PSP is likely to find itself in, and discuss issues pertaining to the use of Taylor's frozen-in hypothesis with the spacecraft's in-situ observations. Title: A Novel Soft X-ray Slitless Imaging Spectrograph for Unique Diagnostics of Hot Coronal Plasma Authors: Caspi, Amir; Shh, Albert Y.; Warren, Harry; Woods, Thomas N.; Mason, James Paul; Steslicki, MArek; Gburek, Szymon; Sylwester, Janusz; DeForest, Craig; Schwartz, Richard; Crowley, Geoff Bibcode: 2018tess.conf41006C Altcode: Solar soft X-ray (SXR) observations from ∼0.2 to ∼3 keV (∼4-60 Å), during both solar flares and quiescent times, provide crucial diagnostics that are not available from observations at other wavelengths. Specifically, SXRs reveal plasma temperature distributions, as well as elemental abundances that probe plasma origins over a wide range of temperatures. Spectrally- and temporally-resolved measurements are essential for understanding the dynamics and evolution of these energetic processes; spatially-resolved measurements are essential for understanding energy transport. The NGSPM study calls out an X-ray spectroscopic imager (T-10) as a high-priority instrument, in particular with a spectral resolution of better than 100 eV for SXR emission lines.

We describe a novel approach for a spectro-spatial imager - combining a pinhole camera with a X-ray transmission diffraction grating - that can achieve the required combination of spectral and angular resolutions at SXR energies. Such an instrument has already been demonstrated as a protoype on a sounding-rocket flight and can be proven thoroughly on a small satellite, specifically as part of the instrument complement of the proposed CubeSat Imaging X-ray Solar Spectrometer (CubIXSS) mission. CubIXSS will measure spectrally- and spatially-resolved SXRs from ~1 to 60 Å (~0.2-10 keV) with ~0.25 Å and ~25 arcsec FWHM resolutions, respectively, from the quiescent and flaring Sun from a 6U CubeSat platform in low-Earth orbit during a nominal 1-year mission. Accordingly, CubIXSS is a pathfinder for larger satellites with improved resolution (<0.1 Å, ~few arcsec) and sensitivity, that could be integrated with focusing optics if desired. Through these groundbreaking new measurements, CubIXSS and future missions will improve our physical understanding of thermal plasma processes and impulsive energy release in the solar corona, from quiet Sun to solar flares. Title: Weakened Magnetization and Onset of Large-scale Turbulence in the Young Solar Wind—Comparisons of Remote Sensing Observations with Simulation Authors: Chhiber, Rohit; Usmanov, Arcadi V.; DeForest, Craig E.; Matthaeus, William H.; Parashar, Tulasi N.; Goldstein, Melvyn L. Bibcode: 2018ApJ...856L..39C Altcode: Recent analysis of Solar-Terrestrial Relations Observatory (STEREO) imaging observations have described the early stages of the development of turbulence in the young solar wind in solar minimum conditions. Here we extend this analysis to a global magnetohydrodynamic (MHD) simulation of the corona and solar wind based on inner boundary conditions, either dipole or magnetogram type, that emulate solar minimum. The simulations have been calibrated using Ulysses and 1 au observations, and allow, within a well-understood context, a precise determination of the location of the Alfvén critical surfaces and the first plasma beta equals unity surfaces. The compatibility of the the STEREO observations and the simulations is revealed by direct comparisons. Computation of the radial evolution of second-order magnetic field structure functions in the simulations indicates a shift toward more isotropic conditions at scales of a few Gm, as seen in the STEREO observations in the range 40-60 R ⊙. We affirm that the isotropization occurs in the vicinity of the first beta unity surface. The interpretation based on early stages of in situ solar wind turbulence evolution is further elaborated, emphasizing the relationship of the observed length scales to the much smaller scales that eventually become the familiar turbulence inertial range cascade. We argue that the observed dynamics is the very early manifestation of large-scale in situ nonlinear couplings that drive turbulence and heating in the solar wind. Title: Evidence for the Magnetic Breakout Model in an Equatorial Coronal-hole Jet Authors: Kumar, Pankaj; Karpen, Judith T.; Antiochos, Spiro K.; Wyper, Peter F.; DeVore, C. Richard; DeForest, Craig E. Bibcode: 2018ApJ...854..155K Altcode: 2018arXiv180108582K Small, impulsive jets commonly occur throughout the solar corona, but are especially visible in coronal holes. Evidence is mounting that jets are part of a continuum of eruptions that extends to much larger coronal mass ejections and eruptive flares. Because coronal-hole jets originate in relatively simple magnetic structures, they offer an ideal testbed for theories of energy buildup and release in the full range of solar eruptions. We analyzed an equatorial coronal-hole jet observed by the Solar Dynamics Observatory (SDO)/AIA on 2014 January 9 in which the magnetic-field structure was consistent with the embedded-bipole topology that we identified and modeled previously as an origin of coronal jets. In addition, this event contained a mini-filament, which led to important insights into the energy storage and release mechanisms. SDO/HMI magnetograms revealed footpoint motions in the primary minority-polarity region at the eruption site, but show negligible flux emergence or cancellation for at least 16 hr before the eruption. Therefore, the free energy powering this jet probably came from magnetic shear concentrated at the polarity inversion line within the embedded bipole. We find that the observed activity sequence and its interpretation closely match the predictions of the breakout jet model, strongly supporting the hypothesis that the breakout model can explain solar eruptions on a wide range of scales. Title: Instruments for Deep Space Weather Prediction and Science Authors: DeForest, C. E.; Laurent, G. Bibcode: 2018LPICo2063.3176D Altcode: We discuss remote space weather monitoring system concepts that could mount on the Deep Space Gateway and provide predictive capability for space weather events including SEP events and CME crossings, and advance heliophysics of the solar wind. Title: Evidence for the Magnetic Breakout Model in AN Equatorial Coronal-Hole Jet Authors: Kumar, P.; Karpen, J.; Antiochos, S. K.; Wyper, P. F.; DeVore, C. R.; DeForest, C. E. Bibcode: 2017AGUFMSH52B..02K Altcode: We analyzed an equatorial coronal-hole jet observed by Solar Dynamic Observatory (SDO)/AtmosphericImaging Assembly (AIA). The source-region magnetic field structure is consistent withthe embedded-bipole topology that we identified and modeled previously as a source of coronal jets. Theinitial brightening was observed below a sigmoid structure about 25 min before the onset of an untwisting jet.A circular magnetic flux rope with a mini-filament rose slowly at the speed of ∼15 km/s , then accelerated(∼126 km/s) during the onset of explosive breakout reconnection. Multiple plasmoids, propagating upward(∼135 km/s) and downward (∼55 km/s ), were detected behind the rising flux rope shortly before andduring explosive breakout reconnection. The jet was triggered when the rising flux rope interacted with theoverlying magnetic structures near the outer spine. This event shows a clear evidence of reconnection not onlybelow the flux rope but also a breakout reconnection above the flux rope. During the breakout reconnection,we observed heating of the flux rope, deflection of loops near the spine, and formation of multiple ribbons.The explosive breakout reconnection destroyed the flux rope that produced an untwisting jet with a speed of∼380 km/s . HMI magnetograms reveal the shear motion at theeruption site, but do not show any significant flux emergence or cancellation during or 2 hours before theeruption. Therefore, the free energy powering this jet most likely originated in magnetic shear concentratedat the polarity inversion line within the embedded bipole-a mini-filament channel-possibly created by helicitycondensation. The result of of a statistical study of multiple jets will also be discussed. Title: Chasing the Great American 2017 Total Solar Eclipse: Coronal Results from NASA's WB-57F High-Altitude Research Aircraft Authors: Caspi, A.; Tsang, C.; DeForest, C. E.; Seaton, D. B.; Bryans, P.; Burkepile, J.; Casey, T. A.; Collier, J.; Darrow, D.; DeLuca, E.; Durda, D. D.; Gallagher, P.; Golub, L.; Judge, P. G.; Laurent, G. T.; Lewis, J.; Mallini, C.; Parent, T.; Propp, T.; Steffl, A.; Tomczyk, S.; Warner, J.; West, M. J.; Wiseman, J.; Zhukov, A. Bibcode: 2017AGUFMSH24A..05C Altcode: Total solar eclipses present rare opportunities to study the complex solar corona, down to altitudes of just a few percent of a solar radius above the surface, using ground-based and airborne observatories that would otherwise be dominated by the intense solar disk and high sky brightness. Studying the corona is critical to gaining a better understanding of physical processes that occur on other stars and astrophysical objects, as well as understanding the dominant driver of space weather that affects human assets at Earth and elsewhere. For example, it is still poorly understood how the corona is heated to temperatures of 1-2 MK globally and up to 5-10 MK above active regions, while the underlying chromosphere is 100 times cooler; numerous theories abound, but are difficult to constrain due to the limited sensitivities and cadences of prior measurements. The origins and stability of coronal fans, and the extent of their reach to the middle and outer corona, are also not well known, limited in large part by sensitivities and fields of view of existing observations. Airborne observations during the eclipse provide unique advantages; by flying in the stratosphere at altitudes of 50 kft or higher, they avoid all weather, the seeing quality is enormously improved, and additional wavelengths such as near- IR also become available due to significantly reduced water absorption. For an eclipse, an airborne observatory can also follow the shadow, increasing the total observing time by 50% or more. We present results of solar coronal measurements from airborne observations of the 2017 Great American Total Solar Eclipse using two of NASA's WB-57 high-altitude research aircraft, each equipped with two 8.7" telescopes feeding high-sensitivity visible (green-line) and medium-wave IR (3-5 μm) cameras operating at high cadence (30 Hz) with 3 arcsec/pixel platescale and ±3 R_sun fields of view. The aircraft flew along the eclipse path, separated by 110 km, to observe a summed 7.5 minutes of totality in both visible and NIR, enabling groundbreaking studies of high-speed wave motions and nanojets in the lower corona, the structure and extent of coronal fans, and constraints on a potential primordial dust ring around the Sun. We review the mission, and the results of analysis on the visible and IR coronal measurements. Title: Planetary Science from NASA's WB-57 Canberra High Altitude Research Aircraft During the Great American Eclipse of 2017 Authors: Tsang, C.; Caspi, A.; DeForest, C. E.; Durda, D. D.; Steffl, A.; Lewis, J.; Wiseman, J.; Collier, J.; Mallini, C.; Propp, T.; Warner, J. Bibcode: 2017AGUFMSH13B2482T Altcode: The Great American Eclipse of 2017 provided an excellent opportunity for heliophysics research on the solar corona and dynamics that encompassed a large number of research groups and projects, including projects flown in the air and in space. Two NASA WB-57F Canberra high altitude research aircraft were launched from NASA's Johnson Space Center, Ellington Field into the eclipse path. At an altitude of 50,000ft, and outfitted with visible and near-infrared cameras, these aircraft provided increased duration of observations during eclipse totality, and much sharper images than possible on the ground. Although the primary mission goal was to study heliophysics, planetary science was also conducted to observe the planet Mercury and to search for Vulcanoids. Mercury is extremely challenging to study from Earth. The 2017 eclipse provided a rare opportunity to observe Mercury under ideal astronomical conditions. Only a handful of near-IR thermal images of Mercury exist, but IR images provide critical surface property (composition, albedo, porosity) information, essential to interpreting lower resolution IR spectra. Critically, no thermal image of Mercury currently exists. By observing the nightside surface during the 2017 Great American Eclipse, we aimed to measure the diurnal temperature as a function of local time (longitude) and attempted to deduce the surface thermal inertia integrated down to a few-cm depth below the surface. Vulcanoids are a hypothesized family of asteroids left over from the formation of the solar system, in the dynamically stable orbits between the Sun and Mercury at 15-45 Rs (4-12° solar elongation). Close proximity to the Sun, plus their small theoretical sizes, make Vulcanoid searches rare and difficult. The 2017 eclipse was a rare opportunity to search for Vulcanoids. If discovered these unique, highly refractory and primordial bodies would have a significant impact on our understanding of solar system formation. Only a handful of deep searches have been conducted. Our observations will only be the second time ever a search for Vulcanoids will have been conducted in the NIR. In this presentation, I will review our NASA flight program, and focus on the planetary science observations that came from the Great American Eclipse of 2017. Title: 3D Polarized Imaging of Coronal Mass Ejections: Chirality of a CME Authors: DeForest, C. E.; de Koning, C. A.; Elliott, H. A. Bibcode: 2017ApJ...850..130D Altcode: We report on a direct polarimetric determination of the chirality of a coronal mass ejection (CME), using the physics of Thomson scattering applied to synoptic polarized images from the Solar Terrestrial Relations Observatories/COR2 coronagraph. We confirmed the determination using in situ magnetic field measurements of the same CME with the ACE spacecraft. CME chirality is related to the helicity ejected from the solar corona along with the mass and field entrained in the CME. It is also important to prediction of the space-weather-relevant Z component of the CME magnetic field. Hence, remote measurement of CME chirality is an important step toward both understanding CME physics and predicting geoeffectiveness of individual CMEs. The polarimetric properties of Thomson scattering are well known and can, in principle, be used to measure the 3D structure of imaged objects in the solar corona and inner heliosphere. However, reduction of that principle to practice has been limited by the twin difficulties of background subtraction and the signal-to-noise ratio in coronagraph data. Useful measurements of the 3D structure require relative photometry at a few percent precision level in each linear polarization component of the K corona. This corresponds to a relative photometric precision of order 10-4 in direct images of the sky before subtraction of the F corona and related signal. Our measurement was enabled by recent developments in signal processing, which enable a better separation of the photometric signal from noise in the synoptic COR2 data. We discuss the relevance of this demonstration measurement to future instrument requirements, and to the future measurements of 3D structures in CMEs and other solar wind features. Title: Global Fluxon Modeling of the Solar Corona and Inner Heliosphere Authors: Lamb, D. A.; DeForest, C. E. Bibcode: 2017AGUFMSH11B2440L Altcode: The fluxon approach to MHD modeling enables simulations of low-beta plasmas in the absence of undesirable numerical effects such as diffusion and magnetic reconnection. The magnetic field can be modeled as a collection of discrete field lines ("fluxons") containing a set amount of magnetic flux in a prescribed field topology. Due to the fluxon model's pseudo-Lagrangian grid, simulations can be completed in a fraction of the time of traditional grid-based simulations, enabling near-real-time simulations of the global magnetic field structure and its influence on solar wind properties. Using SDO/HMI synoptic magnetograms as lower magnetic boundary conditions, and a separate one-dimensional fluid flow model attached to each fluxon, we compare the resulting fluxon relaxations with other commonly-used global models (such as PFSS), and with white-light images of the corona (including the August 2017 total solar eclipse). Finally, we show the computed magnetic field expansion ratio, and the modeled solar wind speed near the coronal-heliospheric transition. Development of the fluxon MHD model FLUX (the Field Line Universal relaXer), has been funded by NASA's Living with a Star program and by Southwest Research Institute. Title: Characterizing coronal structure: Combining remote sensing observations with global MHD modeling to make predictions for Parker Solar Probe and Solar Orbiter missions Authors: Chhiber, R.; Usmanov, A. V.; Matthaeus, W. H.; DeForest, C. E.; Parashar, T.; Goldstein, M. L. Bibcode: 2017AGUFMSH23D2690C Altcode: As the solar plasma flows out from the corona and transitions into the solar wind, it transforms from a magnetically structured, subsonic, and sub-Alfvénic regime into a supersonic and super-Alfvénic flow dominated by hydrodynamics. Recent analysis of remote imaging observations in solar minimum conditions by DeForest et al. (2016) have described the early stages of this transition. Here we extend this analysis to global magnetohydrodynamics simulation of the corona and solar wind based on inner boundary conditions that emulate solar minimum, in anticipation of the first phase of Parker Solar Probe (PSP) observations, which are expected during solar minimum as well. Taken together with the imaging analysis, the simulation results provide more detailed expectations for locations of the Alfvén critical surface and the first plasma beta unity surface moving from the corona into the dynamically active solar wind. The turbulence parameters computed from the simulations also enable estimations of the characteristic scales at which in-situ turbulence may influence the dynamics of the solar wind. Estimations of relevant parameters along a simulated PSP trajectory is presented. This multi-faceted approach may be useful in the context of the upcoming Parker Solar Probe and Solar Orbiter missions, which will explore, for the first time, this transition in the inner heliosphere. Title: Using STEREO Polarized White Light Triplets to Reconstruct Features in a CME Authors: de Koning, C. A.; DeForest, C. E. Bibcode: 2017AGUFMSH22B..05D Altcode: On 2010 April 3, the twin NASA/STEREO spacecraft observed a coronal mass ejection (CME) in total and polarized brightness white light using the SECCHI/COR2 corornagraphs. It has been suggested previously that exploiting the full range of white light imagery may enable reconstruction of a CME's internal features; however, noisy imagery has made this promise difficult to fulfill. Using a recently developed noise-gating process to improve the signal-to-noise ratio in COR2, we demonstrate that we can spatially isolate features within a CME. In particular, we measure the orientation of a white-light cavity. Since such a cavity is often associated with a CME flux rope, we suggest that combining total brightness measurements and degree of polarization imagery can be used to investigate CME flux ropes. Title: Mapping The Territory: What Current Remote Sensing Tells Us To Expect For PSP Authors: DeForest, C. E.; McComas, D. J.; Vourlidas, A.; Howard, R. Bibcode: 2017AGUFMSH21C..06D Altcode: Remote sensing with current coronagraphs affords the best current estimate of plasma conditions PSP will encounter. Over the past few years, analyses of the synoptic data sets from the STEREO/COR2 and STEREO/HI1 imagers have yielded rough locations for critical loci such as the Alfvén and β=1 surfaces. We now present new results from the deepest-field coronagraph sequence made to date: the STEREO-A deep-field campaign. Recently-developed noise reduction techniques and the unique deep-exposure data set reveal small scale motions and fluctuations throughout the visible corona and give new insight into the structure of the outer corona. Title: Noise Gating Solar Images Authors: DeForest, Craig; Seaton, Daniel B.; Darnell, John A. Bibcode: 2017SPD....48.0601D Altcode: I present and demonstrate a new, general purpose post-processing technique, "3D noise gating", that can reduce image noise by an order of magnitude or more without effective loss of spatial or temporal resolution in typical solar applications.Nearly all scientific images are, ultimately, limited by noise. Noise can be direct Poisson "shot noise" from photon counting effects, or introduced by other means such as detector read noise. Noise is typically represented as a random variable (perhaps with location- or image-dependent characteristics) that is sampled once per pixel or once per resolution element of an image sequence. Noise limits many aspects of image analysis, including photometry, spatiotemporal resolution, feature identification, morphology extraction, and background modeling and separation.Identifying and separating noise from image signal is difficult. The common practice of blurring in space and/or time works because most image "signal" is concentrated in the low Fourier components of an image, while noise is evenly distributed. Blurring in space and/or time attenuates the high spatial and temporal frequencies, reducing noise at the expense of also attenuating image detail. Noise-gating exploits the same property -- "coherence" -- that we use to identify features in images, to separate image features from noise.Processing image sequences through 3-D noise gating results in spectacular (more than 10x) improvements in signal-to-noise ratio, while not blurring bright, resolved features in either space or time. This improves most types of image analysis, including feature identification, time sequence extraction, absolute and relative photometry (including differential emission measure analysis), feature tracking, computer vision, correlation tracking, background modeling, cross-scale analysis, visual display/presentation, and image compression.I will introduce noise gating, describe the method, and show examples from several instruments (including SDO/AIA , SDO/HMI, STEREO/SECCHI, and GOES-R/SUVI) that explore the benefits and limits of the technique. Title: First results from the NASA WB-57 airborne observations of the Great American 2017 Total Solar Eclipse Authors: Caspi, Amir; Tsang, Constantine; DeForest, Craig; Seaton, Daniel B.; Bryans, Paul; Tomczyk, Steven; Burkepile, Joan; Judge, Phil; DeLuca, Edward E.; Golub, Leon; Gallagher, Peter T.; Zhukov, Andrei; West, Matthew; Durda, Daniel D.; Steffl, Andrew J. Bibcode: 2017SPD....4810701C Altcode: Total solar eclipses present rare opportunities to study the complex solar corona, down to altitudes of just a few percent of a solar radius above the surface, using ground-based and airborne observatories that would otherwise be dominated by the intense solar disk and high sky brightness. Studying the corona is critical to gaining a better understanding of physical processes that occur on other stars and astrophysical objects, as well as understanding the dominant driver of space weather that affects human assets at Earth and elsewhere. For example, it is still poorly understood how the corona is heated to temperatures of 1-2 MK globally and up to 5-10 MK above active regions, while the underlying chromosphere is 100 times cooler; numerous theories abound, but are difficult to constrain due to the limited sensitivities and cadences of prior measurements. The origins and stability of coronal fans, and the extent of their reach to the middle and outer corona, are also not well known, limited in large part by sensitivities and fields of view of existing observations.Airborne observations during the eclipse provide unique advantages; by flying in the stratosphere at altitudes of 50 kft or higher, they avoid all weather, the seeing quality is enormously improved, and additional wavelengths such as near-IR also become available due to significantly reduced water absorption. For an eclipse, an airborne observatory can also follow the shadow, increasing the total observing time by 50% or more.We present the first results from airborne observations of the 2017 Great American Total Solar Eclipse using two of NASA's WB-57 research aircraft, each equipped with two 8.7" telescopes feeding high-sensitivity visible (green-line) and near-IR (3-5 µm) cameras operating at high cadence (30 Hz) with ~3 arcsec/pixel platescale and ±3 R_sun fields of view. The aircraft will fly along the eclipse path, separated by ~90 km, to observe a summed ~8 minutes of totality in both visible and NIR, enabling groundbreaking studies of high-speed wave motions and nanojets in the lower corona, the structure and extent of coronal fans, and constraints on a potential primordial dust ring around the Sun. Title: Solar Jetlets and Plumes Authors: DeForest, Craig; Antiochos, Spiro K.; DeVore, C. Richard; Karpen, Judith T.; Kumar, Pankaj; Raouafi, Nour-Eddine; Roberts, Merrill; Uritsky, Vadim; Wyper, Peter Bibcode: 2017SPD....4830401D Altcode: We present results of a careful deep-field (low-noise) analysis of evolution and structure of solar plumes using multiple wavelength channels from SDO/AIA. Using new noise-reduction techniques on SDO/AIA images, we reveal myriad small, heating events that appear to be the primary basis of plume formation and sustenance. These events ("jetlets") comprise a dynamic tapestry that forms the more distributed plume itself. We identify the "jetlets" with ejecta that have been previously observed spectroscopically, and distinguish them from the quasi-periodic slow mode waves that are seen as large collective motions. We speculate that the jetlets themselves, which are consistent with multiple interchange reconnection events near the base of the plume, are the primary energy driver heating plasma in the plume envelope.Solar polar (and low-latitude) plumes have been analyzed by many authors over many years. Plumes are bright, persistent vertical structures embedded in coronal holes over quasi-unipolar magnetic flux concentrations. They are EUV-bright in the ~1MK lines, slightly cooler (by ionization fraction) than the surrounding coronal hole, persistent on short timescales of a few hours, and recurrent on timescales of a few days. Their onset has been associated with large X-ray jets, although not all plumes are formed that way. Plumes appear to comprise myriad small "threads" or "strands", and may (or may not) contribute significantly to the solar wind, though they have been associated with myriad small, frequent eruptive ejection events.Our results are new and interesting because they are the lowest-noise, time-resolved observations of polar plumes to date; and they reveal the deep association between small-scale magnetic activity and the formation of the plumes themselves. Title: Constraints on Nonuniform Expansion in Coronal Loops Authors: Kucera, Therese A.; DeForest, Craig; Klimchuk, James A.; Young, Peter R. Bibcode: 2017SPD....4810608K Altcode: We use measurements of coronal loop properties to constrain the hypothesis that coronal loops expand differently in different directions. A long standing problem in understanding coronal loops is that although the magnetic field is expected to expand with altitude and does indeed seem to do so on scales of active regions, individual loops seem to have fairly uniform diameters along the length of the loop. Malanushenko & Schrijver (2013) have suggested that loops may be expanding, but with a non-circular cross section. In this scenario a loop might have a constant width in the plane of the sky, but expand along the line of sight. Furthermore, such loops might be easier to see from the point of view that does not show expansion. We use Hinode/EIS and SDO/AIA data to measure loop intensities, electron densities, temperatures and dimensions in order to determine the extent to which loops may be expanding along the line of sight. Title: Fluxon Global Predictions for the 2017 Eclipse Authors: DeForest, Craig; Lamb, Derek Bibcode: 2017SPD....4810702D Altcode: We present predicted coronal morphologies for the 2017 total solar eclipse, produced using quasi-stationary MHD simulation on a semi-Lagrangian grid with the FLUX code. FLUX uses the "fluxon" approach to ideal MHD: the magnetic field is modeled as a finite-element skeleton of field lines, which experience the familiar magnetic energy density ("pressure") and curvature ("tension") forces. Ongoing and recent work with FLUX enables simulation of solar wind flow and coronal density in the low-beta regime, and permits global 3-D solutions without the use of a supercomputer.Using magnetograms acquired up to one solar rotation before the eclipse, we expect to publish fluxon-derived models 2-3 weeks before the eclipse, and will present those models side-by-side with actual eclipse images to compare the model and actual coronae. Title: The CubeSat Imaging X-ray Solar Spectrometer (CubIXSS) Mission Concept Authors: Caspi, Amir; Shih, Albert Y.; Warren, Harry; DeForest, Craig; Laurent, Glenn Thomas; Schwartz, Richard A.; Woods, Thomas N.; Mason, James; Palo, Scott; Steslicki, Marek; Sylwester, Janusz; Gburek, Szymon; Mrozek, Tomasz; Kowalinski, Miroslaw; Torre, Gabriele; Crowley, Geoffrey; Schattenburg, Mark Bibcode: 2017SPD....4830503C Altcode: Solar soft X-ray (SXR) observations provide important diagnostics of plasma heating, during solar flares and quiescent times. Spectrally- and temporally-resolved measurements are crucial for understanding the dynamics, origins, and evolution of these energetic processes, providing probes both into the temperature distributions and elemental compositions of hot plasmas; spatially-resolved measurements are critical for understanding energy transport and mass flow. A better understanding of the thermal plasma improves our understanding of the relationships between particle acceleration, plasma heating, and the underlying release of magnetic energy during reconnection. We introduce a new proposed small satellite mission, the CubeSat Imaging X-ray Solar Spectrometer (CubIXSS), to measure spectrally- and spatially-resolved SXRs from the quiescent and flaring Sun from a 6U CubeSat platform in low-Earth orbit during a nominal 1-year mission. CubIXSS includes the Amptek X123-FastSDD silicon drift detector, a low-noise, commercial off-the-shelf (COTS) instrument enabling solar SXR spectroscopy from ~0.5 to ~30 keV with ~0.15 keV FWHM spectral resolution with low power, mass, and volume requirements. Multiple detectors and tailored apertures provide sensitivity to a wide range of solar conditions, optimized for a launch during solar minimum. The precise spectra from these instruments will provide detailed measurements of the coronal temperature distribution and elemental abundances from the quiet Sun to active regions and flares. CubIXSS also includes a novel spectro-spatial imager -- the first ever solar imager on a CubeSat -- utilizing a custom pinhole camera and Chandra-heritage X-ray transmission diffraction grating to provide spatially- resolved, full-Sun imaging spectroscopy from ~0.1 to ~10 keV, with ~25 arcsec and ~0.1 Å FWHM spatial and spectral resolutions, respectively. MOXSI’s unique capabilities enable SXR spectroscopy and temperature diagnostics of individual active regions and flares. Through its groundbreaking new measurements, CubIXSS will improve our physical understanding of thermal plasma processes and impulsive energy release in the solar corona, from quiet Sun to solar flares. Title: Noise-gating to Clean Astrophysical Image Data Authors: DeForest, C. E. Bibcode: 2017ApJ...838..155D Altcode: 2017arXiv170306228D I present a family of algorithms to reduce noise in astrophysical images and image sequences, preserving more information from the original data than is retained by conventional techniques. The family uses locally adaptive filters (“noise gates”) in the Fourier domain to separate coherent image structure from background noise based on the statistics of local neighborhoods in the image. Processing of solar data limited by simple shot noise or by additive noise reveals image structure not easily visible in the originals, preserves photometry of observable features, and reduces shot noise by a factor of 10 or more with little to no apparent loss of resolution. This reveals faint features that were either not directly discernible or not sufficiently strongly detected for quantitative analysis. The method works best on image sequences containing related subjects, for example movies of solar evolution, but is also applicable to single images provided that there are enough pixels. The adaptive filter uses the statistical properties of noise and of local neighborhoods in the data to discriminate between coherent features and incoherent noise without reference to the specific shape or evolution of those features. The technique can potentially be modified in a straightforward way to exploit additional a priori knowledge about the functional form of the noise. Title: Challenging Some Contemporary Views of Coronal Mass Ejections. II. The Case for Absent Filaments Authors: Howard, T. A.; DeForest, C. E.; Schneck, U. G.; Alden, C. R. Bibcode: 2017ApJ...834...86H Altcode: When a coronal mass ejection (CME) appears in a coronagraph it often exhibits three parts. This “classic” three-part configuration consists of a bright leading edge, a dark circular- or teardrop-shaped cavity, and a bright core within the cavity. It is generally accepted that these are manifestations of coronal plasma pileup, the driving magnetic flux rope, and the associated eruptive filament, respectively. The latter has become accepted by the community since coronagraph CMEs have been commonly associated with eruptive filaments for over 40 years. In this second part of our series challenging views on CMEs, we present the case that the inner core of the three-part coronagraph CME may not be, and in the most common cases is not, a filament. We present our case in the form of four exhibits showing that most of the CMEs in a broad survey are not associated with an eruptive filament at the Sun, and that the cores of those CMEs that are filament-associated do not geometrically resemble or consist of material from the associated filament. We conclude with a discussion on the possible causes of the bright CME core and what happens to the filament material postlaunch. We discuss how the CME core could arise spontaneously from the eruption of a flux rope from the Sun, or could be the result of a mathematical caustic produced by the geometric projection of a twisted flux rope. Title: Imaging the Breakup of Coronal Structure and the Onset of Turbulence in the Solar Wind Authors: DeForest, C. E. Bibcode: 2016AGUFMSH44A..05D Altcode: The slow solar wind is dominated by gusty, variable structure that has been associated by many authors with turbulence. The slow wind is thought to arise from the vicinity of the coronal streamer belt, which is dominated by quasi-stationary, highly anisotropic, radially aligned density structure shaped by the solar magnetic field. Photometric analysis of the top of the streamers, in the range of apparent distances between roughly 4° and 24° from the Sun, reveals the ultimate fate of the streamers. In the range above 10° from the Sun, where the transition from low-plasma-beta to high-plasma-beta is thought to occur, we have imaged the fading and breakup of quiescent coronal streamers, pseudostreamers, and/or rays (together, "Striae"), and the textural transition at large scales from smooth background flow with sporadic ejecta, to turbulent and variable flow. The result constrains and illuminates turbulent theories of solar wind evolution, and highlights the need for better imaging measurements in this critical transition zone between corona and solar wind - the final unexplored frontier of the heliosphere. Title: Development of a Homogenous Database of Bipolar Active Regions Spanning Four Cycles Authors: Munoz-Jaramillo, A.; Werginz, Z. A.; Vargas-Acosta, J. P.; DeLuca, M. D.; Vargas-Dominguez, S.; Lamb, D. A.; DeForest, C. E.; Longcope, D. W.; Martens, P. Bibcode: 2016AGUFMSH11A2219M Altcode: The solar cycle can be understood as a process that alternates the large-scale magnetic field of the Sun between poloidal and toroidal configurations. Although the process that transitions the solar cycle between toroidal and poloidal phases is still not fully understood, theoretical studies, and observational evidence, suggest that this process is driven by the emergence and decay of bipolar magnetic regions (BMRs) at the photosphere. Furthermore, the emergence of BMRs at the photosphere is the main driver behind solar variability and solar activity in general; making the study of their properties doubly important for heliospheric physics. However, in spite of their critical role, there is still no unified catalog of BMRs spanning multiple instruments and covering the entire period of systematic measurement of the solar magnetic field (i.e. 1975 to present).In this presentation we discuss an ongoing project to address this deficiency by applying our Bipolar Active Region Detection (BARD) code on full disk magnetograms measured by the 512 (1975-1993) and SPMG (1992-2003) instruments at the Kitt Peak Vacuum Telescope (KPVT), SOHO/MDI (1996-2011) and SDO/HMI (2010-present). First we will discuss the results of our revitalization of 512 and SPMG KPVT data, then we will discuss how our BARD code operates, and finally report the results of our cross-callibration across instruments.The corrected and improved KPVT magnetograms will be made available through the National Solar Observatory (NSO) and Virtual Solar Observatory (VSO), including updated synoptic maps produced by running the corrected KPVT magnetograms though the SOLIS pipeline. The homogeneous active region database will be made public by the end of 2017 once it has reached a satisfactory level of quality and maturity. The Figure shows all bipolar active regions present in our database (as of Aug 2016) colored according to the instrument where they were detected. The image also includes the names of the NSF-REU students in charge of the supervision of the detection algorithm and the year in which they worked on the catalog. Marker size is indicative of the total active region flux. Title: Imaging the Top of the Solar Corona and the Young Solar Wind Authors: DeForest, C. E.; Matthaeus, W. H.; Viall, N. M.; Cranmer, S. R. Bibcode: 2016AGUFMSH53A..05D Altcode: We present the first direct visual evidence of the quasi-stationary breakup of solar coronal structure and the rise of turbulence in the young solar wind, directly in the future flight path of Solar Probe. Although the corona and, more recently, the solar wind have both been observed directly with Thomson scattered light, the transition from the corona to the solar wind has remained a mystery. The corona itself is highly structured by the magnetic field and the outflowing solar wind, giving rise to radial "striae" - which comprise the familiar streamers, pseudostreamers, and rays. These striae are not visible in wide-field heliospheric images, nor are they clearly delineated with in-situ measurements of the solar wind. Using careful photometric analysis of the images from STEREO/HI-1, we have, for the first time, directly observed the breakup of radial coronal structure and the rise of nearly-isotropic turbulent structure in the outflowing slow solar wind plasma between 10° (40 Rs) and 20° (80 Rs) from the Sun. These observations are important not only for their direct science value, but for predicting and understanding the conditions expected near SPP as it flies through - and beyond - this final frontier of the heliosphere, the outer limits of the solar corona. Title: Opportunities for Suborbital Space and Atmospheric Research Facilities on Blue Origin's New Shepard Crew Capsule Authors: Wagner, E.; DeForest, C. E. Bibcode: 2016AGUFM.P53C2216W Altcode: With the emergence of the commercial space industry, researchers now have more options than ever for conducting research aboard space-going platforms. Blue Origin's New Shepard spacecraft offers a large-format crew capsule, capable of carrying a wide range of high-altitude and microgravity payloads above the Karman Line (100 km). With high flight rates and short approval timelines, investigators are able to use data from one flight to refine research objectives and quickly fly again, closing the loop on the scientific method and rapidly advancing technology development. Young investigators have ready access to real-world experiences in building flight hardware, and more involved missions are using this low-barrier environment to raise Technology Readiness Level of components or subsystems. This talk will introduce the standard interfaces and operations for payloads already flying within the New Shepard capsule. We will also explore opportunities for custom facilities that would allow researchers access to the space environment at altitudes between 60 and 100 km. We will discuss the unique science that can be conducted in this region, above where balloons can dwell, but below satellite orbits, including investigations in heliophysics, planetary science, and aeronomy. Title: The Future of Space Weather Forecasting with Polarized Wide-Field Imaging Authors: DeForest, C. E.; Howard, T. A. Bibcode: 2016AGUFMSH11C2254D Altcode: Heliospheric imaging has come of age. From the original concept of white light photometry with the Helios spacecraft through to the HIs on board STEREO and current research on the outer limits of the corona, heliospheric imagers have enabled important developments in our understanding of the solar wind and transients within. Future instruments have the potential to revolutionize space weather forecasting. We present a summary of recent progress as it relates to space weather prediction and new directions that a future instrument, which would build on lessons from Coriolis/SMEI and STEREO/HI, can take. Applications include both direct, far more precise 3-D tracking of coronal mass ejections (CMEs) across the inner solar system; measurement of CMEs' internal structures and their evolution; and a more complete, up-to-date understanding ("nowcasting") of prevailing conditions in the outer corona and solar wind. We will review of the status quo of heliospheric imaging and the latest developments in feature detection and measurement. We also explore the benefits of polarized heliospheric imaging, which we believe to be the best next step to advance heliospheric imaging and continue the scientific and operational development of this field. Title: The best of both worlds: Using automatic detection and limited human supervision to create a homogenous magnetic catalog spanning four solar cycles Authors: Muñoz-Jaramillo, Andres; Werginz, Zachary; Vargas-Acosta, Juan Pablo; DeLuca, Michael; Windmueller, J. C.; Zhang, Jie; Longcope, Dana; Lamb, Derek; DeForest, Craig; Vargas-Domínguez, Santiago; Harvey, Jack; Martens, Piet Bibcode: 2016bida.conf.3194M Altcode: 2022arXiv220311908M Bipolar magnetic regions (BMRs) are the cornerstone of solar variability. They are tracers of the large-scale magnetic processes that give rise to the solar cycle, shapers of the solar corona, building blocks of the large-scale solar magnetic field, and significant contributors to the free-energetic budget that gives rise to flares and coronal mass ejections. Surprisingly, no homogeneous catalog of BMRs exists today, in spite of the existence of systematic measurements of the magnetic field since the early 1970's. The purpose of this work is to address this deficiency by creating a homogenous catalog of BMRs from the 1970's until the present. For this purpose, in this paper we discuss the strengths and weaknesses of the automatic and manual detection of BMRs and how both methods can be combined to form the basis of our Bipolar Active Region Detection (BARD) code and its supporting human supervision module. At present, the BARD catalog contains more than 10,000 unique BMRs tracked and characterized during every day of their observation. Here we also discuss our future plans for the creation of an extended multi-scale magnetic catalog combining the SWAMIS and BARD catalogs. Title: Long-term Trends in the Solar Wind Proton Measurements Authors: Elliott, Heather A.; McComas, David J.; DeForest, Craig E. Bibcode: 2016ApJ...832...66E Altcode: 2016arXiv161006063E We examine the long-term time evolution (1965-2015) of the relationships between solar wind proton temperature (T p) and speed (V p) and between the proton density (n p) and speed using OMNI solar wind observations taken near Earth. We find a long-term decrease in the proton temperature-speed (T p-V p) slope that lasted from 1972 to 2010, but has been trending upward since 2010. Since the solar wind proton density-speed (n p-V p) relationship is not linear like the T p-V p relationship, we perform power-law fits for n p-V p. The exponent (steepness in the n p-V p relationship) is correlated with the solar cycle. This exponent has a stronger correlation with current sheet tilt angle than with sunspot number because the sunspot number maxima vary considerably from cycle to cycle and the tilt angle maxima do not. To understand this finding, we examined the average n p for different speed ranges, and found that for the slow wind n p is highly correlated with the sunspot number, with a lag of approximately four years. The fast wind n p variation was less, but in phase with the cycle. This phase difference may contribute to the n p-V p exponent correlation with the solar cycle. These long-term trends are important since empirical formulas based on fits to T p and V p data are commonly used to identify interplanetary coronal mass ejections, but these formulas do not include any time dependence. Changes in the solar wind density over a solar cycle will create corresponding changes in the near-Earth space environment and the overall extent of the heliosphere. Title: Fading Coronal Structure and the Onset of Turbulence in the Young Solar Wind Authors: DeForest, C. E.; Matthaeus, W. H.; Viall, N. M.; Cranmer, S. R. Bibcode: 2016ApJ...828...66D Altcode: 2016arXiv160607718D Above the top of the solar corona, the young, slow solar wind transitions from low-β, magnetically structured flow dominated by radial structures to high-β, less structured flow dominated by hydrodynamics. This transition, long inferred via theory, is readily apparent in the sky region close to 10° from the Sun in processed, background-subtracted solar wind images. We present image sequences collected by the inner Heliospheric Imager instrument on board the Solar-Terrestrial Relations Observatory (STEREO/HI1) in 2008 December, covering apparent distances from approximately 4° to 24° from the center of the Sun and spanning this transition in the large-scale morphology of the wind. We describe the observation and novel techniques to extract evolving image structure from the images, and we use those data and techniques to present and quantify the clear textural shift in the apparent structure of the corona and solar wind in this altitude range. We demonstrate that the change in apparent texture is due both to anomalous fading of the radial striae that characterize the corona and to anomalous relative brightening of locally dense puffs of solar wind that we term “flocculae.” We show that these phenomena are inconsistent with smooth radial flow, but consistent with the onset of hydrodynamic or magnetohydrodynamic instabilities leading to a turbulent cascade in the young solar wind. Title: A small mission concept to the Sun-Earth Lagrangian L5 point for innovative solar, heliospheric and space weather science Authors: Lavraud, B.; Liu, Y.; Segura, K.; He, J.; Qin, G.; Temmer, M.; Vial, J. -C.; Xiong, M.; Davies, J. A.; Rouillard, A. P.; Pinto, R.; Auchère, F.; Harrison, R. A.; Eyles, C.; Gan, W.; Lamy, P.; Xia, L.; Eastwood, J. P.; Kong, L.; Wang, J.; Wimmer-Schweingruber, R. F.; Zhang, S.; Zong, Q.; Soucek, J.; An, J.; Prech, L.; Zhang, A.; Rochus, P.; Bothmer, V.; Janvier, M.; Maksimovic, M.; Escoubet, C. P.; Kilpua, E. K. J.; Tappin, J.; Vainio, R.; Poedts, S.; Dunlop, M. W.; Savani, N.; Gopalswamy, N.; Bale, S. D.; Li, G.; Howard, T.; DeForest, C.; Webb, D.; Lugaz, N.; Fuselier, S. A.; Dalmasse, K.; Tallineau, J.; Vranken, D.; Fernández, J. G. Bibcode: 2016JASTP.146..171L Altcode: We present a concept for a small mission to the Sun-Earth Lagrangian L5 point for innovative solar, heliospheric and space weather science. The proposed INvestigation of Solar-Terrestrial Activity aNd Transients (INSTANT) mission is designed to identify how solar coronal magnetic fields drive eruptions, mass transport and particle acceleration that impact the Earth and the heliosphere. INSTANT is the first mission designed to (1) obtain measurements of coronal magnetic fields from space and (2) determine coronal mass ejection (CME) kinematics with unparalleled accuracy. Thanks to innovative instrumentation at a vantage point that provides the most suitable perspective view of the Sun-Earth system, INSTANT would uniquely track the whole chain of fundamental processes driving space weather at Earth. We present the science requirements, payload and mission profile that fulfill ambitious science objectives within small mission programmatic boundary conditions. Title: The SPICE Spectral Imager on Solar Orbiter: Linking the Sun to the Heliosphere Authors: Fludra, Andrzej; Haberreiter, Margit; Peter, Hardi; Vial, Jean-Claude; Harrison, Richard; Parenti, Susanna; Innes, Davina; Schmutz, Werner; Buchlin, Eric; Chamberlin, Phillip; Thompson, William; Gabriel, Alan; Morris, Nigel; Caldwell, Martin; Auchere, Frederic; Curdt, Werner; Teriaca, Luca; Hassler, Donald M.; DeForest, Craig; Hansteen, Viggo; Carlsson, Mats; Philippon, Anne; Janvier, Miho; Wimmer-Schweingruber, Robert; Griffin, Douglas; Davila, Joseph; Giunta, Alessandra; Waltham, Nick; Eccleston, Paul; Gottwald, Alexander; Klein, Roman; Hanley, John; Walls, Buddy; Howe, Chris; Schuehle, Udo Bibcode: 2016cosp...41E.607F Altcode: The SPICE (Spectral Imaging of the Coronal Environment) instrument is one of the key remote sensing instruments onboard the upcoming Solar Orbiter Mission. SPICE has been designed to contribute to the science goals of the mission by investigating the source regions of outflows and ejection processes which link the solar surface and corona to the heliosphere. In particular, SPICE will provide quantitative information on the physical state and composition of the solar atmosphere plasma. For example, SPICE will access relative abundances of ions to study the origin and the spatial/temporal variations of the 'First Ionization Potential effect', which are key signatures to trace the solar wind and plasma ejections paths within the heliosphere. Here we will present the instrument and its performance capability to attain the scientific requirements. We will also discuss how different observation modes can be chosen to obtain the best science results during the different orbits of the mission. To maximize the scientific return of the instrument, the SPICE team is working to optimize the instrument operations, and to facilitate the data access and their exploitation. Title: Inward Motions in the Outer Solar Corona between 7 and 12 R ⊙: Evidence for Waves or Magnetic Reconnection Jets? Authors: Tenerani, Anna; Velli, Marco; DeForest, Craig Bibcode: 2016ApJ...825L...3T Altcode: DeForest et al. used synoptic visible-light image sequences from the COR2 coronagraph on board the STEREO-A spacecraft to identify inbound wave motions in the outer corona beyond 7 solar radii and inferred, from the observation, that the Alfvén surface separating the magnetically dominated corona from the flow dominated wind must be located beyond at least 12 solar radii from the Sun over polar coronal holes and beyond 15 solar radii in the streamer belt. Here, we attempt identification of the observed inward signal by theoretically reconstructing height-speed diagrams and comparing them to the observed profiles. Interpretation in terms of Alfvén waves or Alfvénic turbulence appears to be ruled out by the fact that the observed signal shows a deceleration of inward motion when approaching the Sun. Fast magnetoacoustic waves are not directly ruled out in this way, as it is possible for inward waves observed in quadrature, but not propagating exactly radially, to suffer total reflection as the Alfvén speed rises close to the Sun. However, the reconstructed signal in the height-speed diagram has the wrong concavity. A final possibility is decelerating reconnection jets, most probably from component reconnection, in the accelerating wind: the profile in this case appears to match the observations very well. This interpretation does not alter the conclusion that the Alfvén surface must be at least 12 solar radii from the photosphere. Further observations should help constrain this process, never identified previously in this way, in the distance range from 7 to 12 solar radii. Title: Solar abundances with the SPICE spectral imager on Solar Orbiter Authors: Giunta, Alessandra; Haberreiter, Margit; Peter, Hardi; Vial, Jean-Claude; Harrison, Richard; Parenti, Susanna; Innes, Davina; Schmutz, Werner; Buchlin, Eric; Chamberlin, Phillip; Thompson, William; Bocchialini, Karine; Gabriel, Alan; Morris, Nigel; Caldwell, Martin; Auchere, Frederic; Curdt, Werner; Teriaca, Luca; Hassler, Donald M.; DeForest, Craig; Hansteen, Viggo; Carlsson, Mats; Philippon, Anne; Janvier, Miho; Wimmer-Schweingruber, Robert; Griffin, Douglas; Baudin, Frederic; Davila, Joseph; Fludra, Andrzej; Waltham, Nick; Eccleston, Paul; Gottwald, Alexander; Klein, Roman; Hanley, John; Walls, Buddy; Howe, Chris; Schuehle, Udo; Gyo, Manfred; Pfiffner, Dany Bibcode: 2016cosp...41E.681G Altcode: Elemental composition of the solar atmosphere and in particular abundance bias of low and high First Ionization Potential (FIP) elements are a key tracer of the source regions of the solar wind. These abundances and their spatio-temporal variations, as well as the other plasma parameters , will be derived by the SPICE (Spectral Imaging of the Coronal Environment) EUV spectral imager on the upcoming Solar Orbiter mission. SPICE is designed to provide spectroheliograms (spectral images) using a core set of emission lines arising from ions of both low-FIP and high-FIP elements. These lines are formed over a wide range of temperatures, enabling the analysis of the different layers of the solar atmosphere. SPICE will use these spectroheliograms to produce dynamic composition maps of the solar atmosphere to be compared to in-situ measurements of the solar wind composition of the same elements (i.e. O, Ne, Mg, Fe). This will provide a tool to study the connectivity between the spacecraft (the Heliosphere) and the Sun. We will discuss the SPICE capabilities for such composition measurements. Title: An Emerging Magnetic Flux Catalog for SOHO/MDI Authors: Lamb, Derek; Munoz-Jaramillo, Andres; DeForest, Craig Bibcode: 2016SPD....4730701L Altcode: We present a catalog of emerging magnetic flux events covering the entirety of the 15-year-long SOHO/MDI 96-minute magnetogram dataset. Such a catalog has myriad uses in studies of the solar dynamo and solar cycle. Our catalog is designed to mimic as nearly as possible the Emerging Flux region catalog produced for SDO/HMI, allowing continuity across missions and solar cycles. We will present details of the algorithm for identifying emerging flux events, special considerations for MDI as opposed to HMI, detailed examples of some detected emerging flux regions, and a brief overview of statistics of the entire catalog. The catalog will be available for querying through the Heliophysics Event Knowledgebase, as well as for direct downloading from Southwest Research Institute. This work has been supported by NASA Grant NNX14AJ67G through the Heliophysics Data Environment Enhancements program. Title: Imaging the Transition from Corona to Solar Wind Authors: DeForest, Craig; Howard, Tim A.; Howard, Russell A.; Tenerani, Anna Bibcode: 2016SPD....4710205D Altcode: The region around the Alfvén surface -- the last frontier of the solar system -- is largely unexplored, mostly because of the difficulty of detecting the surface itself. Many important transitions happen between the mid-to-outer corona and the innermost heliosphere, including: the transition to superAlfvénic flow; the transition from structured, highly anisotropic structure to nearly isotropic turbulent structures; and the formation of identifiable, separable fast and slow wind streams. We will report new results from two recent imaging campaigns -- one with STEREO and one with SOHO/LASCO (coincidentally performed on the 20th anniversary of the first SOHO campaign) -- to explore and image the transition to turbulent flow and the outer boundary of the corona. Title: Inward Motions in the Outer Solar Corona Between 6 And 12 R : Evidence For Waves or Magnetic Reconnection Jets? Authors: Velli, Marco; Tenerani, Anna; DeForest, Craig Bibcode: 2016SPD....4740205V Altcode: DeForest et al. (2014) used synoptic visible-light image sequences from the COR2 coronagraph on board the STEREO-A spacecraft to identify inbound wave motions in the outer corona beyond 6 solar radii and inferred, from the observation, that the Alfven surface separating the magnetically dominated corona from the ow dominated wind must be located at least 12 solar radii from the Sun over polar coronal holes and 15 solar radii in the streamer belt. Here we will discuss both this and previous observations of inflows further down and attempt identification of the observed inward signals. We will theoretically reconstruct height-speed diagrams and compare them to the observed profiles. Interpretation in terms of Alfven / magnetoacouatic modes or Alfvenic turbulence appears to be ruled out by the fact that the observed signal shows a deceleration of inward motion when approaching the Sun. Fast magnetoacoustic waves are not directly ruled out in this way, as it is possible for inward waves observed in quadrature, but not propagating exactly radially, to suffer total reflection as the Alfven speed rises close to the Sun. However, the reconstructed signal in the height speed diagram has the wrong concavity. A final possibility is decelerating reconnection jets, most probably from component reconnection, in the accelerating wind: the profile in this case appears to match the observations very well. This interpretation does not alter the conclusion that the Alfven surface must be at least 12 solar radii from the photosphere. Title: First flight of SMASH, the SwRI Miniature Assembly for Solar Hard X-rays Authors: Caspi, Amir; Laurent, Glenn Thomas; Shoffner, Michael; Higuera Caubilla, David; Meurisse, Jeremie; Smith, Kelly; Shih, Albert Y.; Saint-Hilaire, Pascal; DeForest, Craig; Mansour, Nagi N.; Hathaway, David H. Bibcode: 2016SPD....4720601C Altcode: The SwRI Miniature Assembly for Solar Hard X-rays (SMASH) was successfully flown from Antarctica in January (19-30) 2016, as a piggy-back instrument on the Gamma-Ray Imager/Polarimeter for Solar flares (GRIPS) high altitude balloon payload. SMASH is a technological demonstration of a new miniaturized hard X-ray (HXR) detector for use on CubeSats and other small spacecraft, including the proposed CubeSat Imaging X-ray Solar Spectrometer (CubIXSS).HXRs are the observational signatures of energetic processes on the Sun, including plasma heating and particle acceleration. One of the goals of CubIXSS will be to address the question of how plasma is heated during solar flares, including the relationship between thermal plasma and non-thermal particles. SMASH demonstrated the space-borne application of the commercial off-the-shelf Amptek X123-CdTe, a miniature cadmium telluride photon-counting HXR spectrometer. The CdTe detector has a physical area of 25 mm^2 and 1 mm fully-depleted thickness, with a ~100 micron Be window; with on-board thermoelectric cooling and pulse pile-up rejection, it is sensitive to solar photons from ~5 to ~100 keV with ~0.5-1.0 keV FWHM resolution. Photons are accumulated into histogram spectra with customizable energy binning and integration time. With modest resource requirements (~1/8 U, ~200 g, ~2.5 W) and low cost (~$10K), the X123-CdTe is an attractive solution for HXR measurements from budget- and resource-limited platforms such as CubeSats. SMASH flew two identical X123-CdTe detectors for redundancy and increased collecting area; the supporting electronics (power, CPU) were largely build-to-print using the Miniature X-ray Solar Spectrometer (MinXSS) CubeSat design.We review the SMASH mission, design, and detector performance during the 12-day Antarctic flight. We present current progress on our data analysis of observed solar flares, and discuss future applications of the space-qualified X123-CdTe detector, including the CubIXSS mission concept that incorporates two such detectors. Title: B-SSIPP: A Miniature Solar Observatory for Rocket or Balloon Flight Authors: DeForest, Craig; Laurent, Glenn Thomas; Diller, Jed; Brownsberger, Judy Bibcode: 2016SPD....47.0803D Altcode: The Southwest Solar Instrument Pointing Package (SSIPP) is a miniature solar observatory for flight application. Conceived as a way to lower barriers to entry to spaceflight, SSIPP conditions a broadband solar beam for use by an IR, visible, or UV instrument on an optical table -- just as do ground-based observatories. The beam is conditioned by a closed-loop tip/tilt pointing system that can lock onto the Sun over a 20° cone of angles, and maintain arcsecond-class pointing from a dynamic flight platform. SSIPP was originally conceived as an instrument platform for the XCOR Lynx suborbital sportsrocket. It has been adapted for ballloon flight, incorporating a novel coarse pointing system that measures torsional pendulation in-flight to construct a stable pointing law on-the-fly. First flight is projected for June 2016 (shortly after SPD). We present status, major design elements, and future plans for the platform. Title: Comparing Loop Cross Sections Observed with Hi-C and AIA/SDO Authors: Klimchuk, James A.; DeForest, Craig Bibcode: 2016SPD....47.0301K Altcode: Many studies have reported coronal loop widths measured with AIA/SDO, TRACE, and other data. For warm loops (T ~ 1 MK), the characteristic diameter is about 1500 km. Sub-structure is likely to exist on smaller scales, but the envelope of the "strands" has this typical size. Since 1500 km (2 arcsec) is not large compared to the spatial resolution of the observations, there remained a question about whether the loops are actually much thinner. To address this concern, we have measured the widths of several loops observed at 193 A by both AIA and the Hi-C rocket experiment. Hi-C has 3-6 times better spatial resolution, so if the loops are substantially unresolved by AIA, it should be readily apparent. We find that the measured widths are very similar. Small differences (< 25%) are explainable by uncertainties in the point spread functions. We conclude that previous measurements of loop widths made by AIA and TRACE are essentially correct. We also find little evidence for loop sub-structure at the resolution of Hi-C. The individual strands that comprise loops are therefore smaller than 200 km. These results have important implications for coronal heating. Title: The Rapid Acquisition Imaging Spectrograph Experiment (RAISE) Sounding Rocket Investigation Authors: Laurent, Glenn T.; Hassler, Donald M.; Deforest, Craig; Slater, David D.; Thomas, Roger J.; Ayres, Thomas; Davis, Michael; de Pontieu, Bart; Diller, Jed; Graham, Roy; Michaelis, Harald; Schuele, Udo; Warren, Harry Bibcode: 2016JAI.....540006L Altcode: We present a summary of the solar observing Rapid Acquisition Imaging Spectrograph Experiment (RAISE) sounding rocket program including an overview of the design and calibration of the instrument, flight performance, and preliminary chromospheric results from the successful November 2014 launch of the RAISE instrument. The RAISE sounding rocket payload is the fastest scanning-slit solar ultraviolet imaging spectrograph flown to date. RAISE is designed to observe the dynamics and heating of the solar chromosphere and corona on time scales as short as 100-200ms, with arcsecond spatial resolution and a velocity sensitivity of 1-2km/s. Two full spectral passbands over the same one-dimensional spatial field are recorded simultaneously with no scanning of the detectors or grating. The two different spectral bands (first-order 1205-1251Å and 1524-1569Å) are imaged onto two intensified Active Pixel Sensor (APS) detectors whose focal planes are individually adjusted for optimized performance. RAISE reads out the full field of both detectors at 5-10Hz, recording up to 1800 complete spectra (per detector) in a single 6-min rocket flight. This opens up a new domain of high time resolution spectral imaging and spectroscopy. RAISE is designed to observe small-scale multithermal dynamics in Active Region (AR) and quiet Sun loops, identify the strength, spectrum and location of high frequency waves in the solar atmosphere, and determine the nature of energy release in the chromospheric network. Title: The utility of polarized heliospheric imaging for space weather monitoring Authors: DeForest, C. E.; Howard, T. A.; Webb, D. F.; Davies, J. A. Bibcode: 2016SpWea..14...32D Altcode: A polarizing heliospheric imager is a critical next generation tool for space weather monitoring and prediction. Heliospheric imagers can track coronal mass ejections (CMEs) as they cross the solar system, using sunlight scattered by electrons in the CME. This tracking has been demonstrated to improve the forecasting of impact probability and arrival time for Earth-directed CMEs. Polarized imaging allows locating CMEs in three dimensions from a single vantage point. Recent advances in heliospheric imaging have demonstrated that a polarized imager is feasible with current component technology.Developing this technology to a high technology readiness level is critical for space weather relevant imaging from either a near-Earth or deep-space mission. In this primarily technical review, we developpreliminary hardware requirements for a space weather polarizing heliospheric imager system and outline possible ways to flight qualify and ultimately deploy the technology operationally on upcoming specific missions. We consider deployment as an instrument on NOAA's Deep Space Climate Observatory follow-on near the Sun-Earth L1 Lagrange point, as a stand-alone constellation of smallsats in low Earth orbit, or as an instrument located at the Sun-Earth L5 Lagrange point. The critical first step is the demonstration of the technology, in either a science or prototype operational mission context. Title: New Instruments for Spectrally-Resolved Solar Soft X-ray Observations from CubeSats, and Larger Missions Authors: Caspi, A.; Shih, A.; Warren, H. P.; DeForest, C. E.; Woods, T. N. Bibcode: 2015AGUFMSH13B2444C Altcode: 2015AGUFMSH13B2444D Solar soft X-ray (SXR) observations provide important diagnostics of plasma heating, during solar flares and quiescent times. Spectrally- and temporally-resolved measurements are crucial for understanding the dynamics and evolution of these energetic processes; spatially-resolved measurements are critical for understanding energy transport. A better understanding of the thermal plasma informs our interpretation of hard X-ray (HXR) observations of nonthermal particles, improving our understanding of the relationships between particle acceleration, plasma heating, and the underlying release of magnetic energy during reconnection. We introduce a new proposed mission, the CubeSat Imaging X-ray Solar Spectrometer (CubIXSS), to measure spectrally- and spatially-resolved SXRs from the quiescent and flaring Sun from a 6U CubeSat platform in low-Earth orbit during a nominal 1-year mission. CubIXSS includes the Amptek X123-SDD silicon drift detector, a low-noise, commercial off-the-shelf (COTS) instrument enabling solar SXR spectroscopy from ~0.5 to ~30 keV with ~0.15 keV FWHM spectral resolution with low power, mass, and volume requirements. An X123-CdTe cadmium-telluride detector is also included for ~5-100 keV HXR spectroscopy with ~0.5-1 keV FWHM resolution. CubIXSS also includes a novel spectro-spatial imager -- the first ever solar imager on a CubeSat -- utilizing a pinhole aperture and X-ray transmission diffraction grating to provide full-Sun imaging from ~0.1 to ~10 keV, with ~25 arcsec and ~0.1 Å FWHM spatial and spectral resolutions, respectively. We discuss scaled versions of these instruments, with greater sensitivity and dynamic range, and significantly improved spectral and spatial resolutions for the imager, for deployment on larger platforms such as Small Explorer missions. Title: Synthetic White-light Imagery for the Wide-field Imager for Solar Probe Plus (WISPR) Authors: Liewer, P. C.; Thernisien, A. F.; Vourlidas, A.; Howard, R.; DeForest, C. E.; DeJong, E.; Desai, A. Bibcode: 2015AGUFMSH31C2426L Altcode: The Solar Probe Plus trajectory, approaching within 10 solar radii, will enable the white light imager, WISPR, to fly through corona features now only imaged remotely. The dependency of the Thomson scattering on the imaging geometry (distance and angle from the Sun) dictates that the outer WISPR telescope will be sensitive to the emission from plasma close to the spacecraft, in contrast to the situation for imaging from Earth orbit. Thus WISPR will be the first 'local' imager providing a crucial link between the large-scale corona and SPP's in-situ measurements. The high speed at perihelion will provide tomographic-like views of coronal structures at ≤1° resolution. As SPP approaches perihelion, WISPR, with a 95° radial by 58° transverse field of view, will resolve the fine-scale structure with high spatial resolution. To prepare for this unprecedented viewing of the structure of the inner corona, we are creating synthetic white light images and animations from the WISPR viewpoint using the white-light ray-tracing package developed at NRL (available through SolarSoft). We will present simulated observations of multi-strand models of coronal streamers and flux ropes of various size and make comparisons with views from Earth, Solar Orbiter and SPP. Analysis techniques for WISPR images will also be discussed. Title: Contextualizing Solar Cycle 24: Report on the Development of a Homogenous Database of Bipolar Active Regions Spanning Four Cycles Authors: Munoz-Jaramillo, A.; Werginz, Z. A.; DeLuca, M. D.; Vargas-Acosta, J. P.; Longcope, D. W.; Harvey, J. W.; Martens, P.; Zhang, J.; Vargas-Dominguez, S.; DeForest, C. E.; Lamb, D. A. Bibcode: 2015AGUFMSH33D..06M Altcode: The solar cycle can be understood as a process that alternates the large-scale magnetic field of the Sun between poloidal and toroidal configurations. Although the process that transitions the solar cycle between toroidal and poloidal phases is still not fully understood, theoretical studies, and observational evidence, suggest that this process is driven by the emergence and decay of bipolar magnetic regions (BMRs) at the photosphere. Furthermore, the emergence of BMRs at the photosphere is the main driver behind solar variability and solar activity in general; making the study of their properties doubly important for heliospheric physics. However, in spite of their critical role, there is still no unified catalog of BMRs spanning multiple instruments and covering the entire period of systematic measurement of the solar magnetic field (i.e. 1975 to present).In this presentation we discuss an ongoing project to address this deficiency by applying our Bipolar Active Region Detection (BARD) code on full disk magnetograms measured by the 512 (1975-1993) and SPMG (1992-2003) instruments at the Kitt Peak Vacuum Telescope (KPVT), SOHO/MDI (1996-2011) and SDO/HMI (2010-present). First we will discuss the results of our revitalization of 512 and SPMG KPVT data, then we will discuss how our BARD code operates, and finally report the results of our cross-callibration.The corrected and improved KPVT magnetograms will be made available through the National Solar Observatory (NSO) and Virtual Solar Observatory (VSO), including updated synoptic maps produced by running the corrected KPVT magnetograms though the SOLIS pipeline. The homogeneous active region database will be made public by the end of 2017 once it has reached a satisfactory level of quality and maturity. The Figure shows all bipolar active regions present in our database (as of Aug 2015) colored according to the sign of their leading polarity. Marker size is indicative of the total active region flux. Anti-Hale regions are shown using solid markers. Title: Remote sensing of plasma motion and turbulence near the Alfvén surface Authors: DeForest, C. E. Bibcode: 2015AGUFMSH44A..01D Altcode: Despite a rich nearly-century-long history, Thomson scattering has not been fully exploited as a remote-sensing tool in the corona and nascent solar wind. In particular, stable deep-space coronagraphs such as SOHO/LASCO and STEREO/SECCHI enable time-dependent, photometric analyses that transcend basic feature tracking and brightness estimation. These techniques offer direct insight into the plasma conditions in the outer corona. In particular, fluctuations in the outer coronal brightness comprise both the familiar inhomogeneous "blobs" of material first tracked quantitatively with SOHO/LASCO, and also a recently-discovered compressive wave field that permits remote probing of the plasma even though individual wave fronts do not stand out visually. I will discuss recent and current measurements of this wave field in the outer corona as a means to probe outer coronal heating and wind acceleration near the transition from corona to heliosphere (known as the Alfvén surface); and present current results from a study of the transition from mostly smooth to mostly turbulent flow in the nascent solar wind. Title: 2-D and 3-D Heliospheric Imaging from LEO, L1 and L5: Instruments, Vantage Points, and Applications Authors: DeForest, C. E. Bibcode: 2015AGUFMSH14A..03D Altcode: Heliospheric imaging has come of age scientifically, and multiple heliospheric imagers are either operating or being built to operate on scientific missions. Much study and effort has been put into the advantages of solar wind imaging for space weather prediction. For example, CME tracking (either in 3-D with polarization, or in an image plane from a vantage far from Earth) has the potential to greatly increase arrival time predictions. Likewise, higher spatial and temporal resolution could provide critical clues about the important N/S component of the entrained magnetic field, by connecting signed surface magnetograms of the Sun to particular structures observed in the corona and, later, in the ICME. I will discuss the current state of understanding of polarized and/or high resolution heliospheric imaging as it relates to space weather forecasting, the relative advantages of an instrument at LEO, L1, or L5, and desiderata to exploit currently-validated and under-consideration techniques in an operational, prototype, or scientific next-generation solar wind imaging experiment. Title: Requirements for an Operational Coronagraph Authors: Howard, R.; Vourlidas, A.; Harrison, R. A.; Bisi, M. M.; Plunkett, S. P.; Socker, D. G.; Eyles, C. J.; Webb, D. F.; DeForest, C. E.; Davies, J. A.; Howard, T. A.; de Koning, C. A.; Gopalswamy, N.; Davila, J. M.; Tappin, J.; Jackson, B. V. Bibcode: 2015AGUFMSH14A..02H Altcode: Coronal mass ejections (CMEs) have been shown to be the major driver of the non-recurrent space weather events and geomagnetic storms. The utility of continuously monitoring such events has been very effectively demonstrated by the LASCO experiment on the SOHO mission. However SOHO is aging, having been launched 20 years ago on Dec 2, 1995. The STEREO mission, in which two spacecraft in orbits about the sun are drifting away from earth, has shown the utility of multiple viewpoints off the sun-earth line. Up to now the monitoring of CMES has been performed by scientific instruments such as LASCO and SECCHI with capabilities beyond those required to record the parameters that are needed to forecast the impact at earth. However, there is great interest within the US NOAA and the UK Met Office to launch operational coronagraphs to L1 and L5. An ad-hoc group was formed to define the requirements of the L5 coronagraph. In this paper we present some requirements that must be met by operational coronagraphs. The Office of Naval Research is gratefully acknowledged. Title: Erratum: “Feasibility of Heliospheric Imaging from Near Earth” (2015, ApJ, 804, 126) Authors: DeForest, C. E.; Howard, T. A. Bibcode: 2015ApJ...813..139D Altcode: No abstract at ADS Title: Turbulence in the Solar Wind Measured with Comet Tail Test Particles Authors: DeForest, C. E.; Matthaeus, W. H.; Howard, T. A.; Rice, D. R. Bibcode: 2015ApJ...812..108D Altcode: By analyzing the motions of test particles observed remotely in the tail of Comet Encke, we demonstrate that the solar wind undergoes turbulent processing enroute from the Sun to the Earth and that the kinetic energy entrained in the large-scale turbulence is sufficient to explain the well-known anomalous heating of the solar wind. Using the heliospheric imaging (HI-1) camera on board NASA's STEREO-A spacecraft, we have observed an ensemble of compact features in the comet tail as they became entrained in the solar wind near 0.4 AU. We find that the features are useful as test particles, via mean-motion analysis and a forward model of pickup dynamics. Using population analysis of the ensemble's relative motion, we find a regime of random-walk diffusion in the solar wind, followed, on larger scales, by a surprising regime of semiconfinement that we attribute to turbulent eddies in the solar wind. The entrained kinetic energy of the turbulent motions represents a sufficient energy reservoir to heat the solar wind to observed temperatures at 1 AU. We determine the Lagrangian-frame diffusion coefficient in the diffusive regime, derive upper limits for the small scale coherence length of solar wind turbulence, compare our results to existing Eulerian-frame measurements, and compare the turbulent velocity with the size of the observed eddies extrapolated to 1 AU. We conclude that the slow solar wind is fully mixed by turbulence on scales corresponding to a 1-2 hr crossing time at Earth; and that solar wind variability on timescales shorter than 1-2 hr is therefore dominated by turbulent processing rather than by direct solar effects. Title: Feasibility of Heliospheric Imaging from Near Earth Authors: DeForest, C. E.; Howard, T. A. Bibcode: 2015ApJ...804..126D Altcode: Imaging solar wind structures via Thomson scattered sunlight has proved important to understanding the inner heliosphere. The principal challenge of heliospheric imaging is background subtraction: typical solar wind features are fainter than the zodiacal light and starfield by 2-3 orders of magnitude. Careful post-processing is required to separate the solar wind signal from the static background. Remnant background, and not photon noise, is the dominant noise source in current STEREO data. We demonstrate that 10× shorter exposure times would not strongly affect the noise level in these data. Further, we demonstrate that current processing techniques are sufficient to separate not only the existing background of the STEREO images but also diffuse variable backgrounds such as are expected to be seen from low Earth orbit. We report on a hare-and-hounds style study, demonstrating blind signal extraction from STEREO/HI-2 data that have been degraded by the addition of large-scale, time-dependent artifacts to simulate viewing through airglow or high-altitude aurora. We demonstrate removal of these effects via image processing, with little degradation compared to the original. Even with as few as three highly degraded source images over 48 hr, it is possible to detect and track large coronal mass ejections more than 40° from the Sun. This implies that neither the high altitude aurora discovered by Coriolis/SMEI, nor airglow effects seen from low Earth orbit, are impediments to a hypothetical next-generation heliospheric imager in low Earth orbit; and also that post-processing is as important to heliospheric image qualitiy as are optical contamination effects. Title: Measuring the Turbulent Solar Wind Authors: DeForest, Craig; Matthaeus, William; Howard, Tim Bibcode: 2015TESS....110806D Altcode: The slow solar wind is turbulent, a fact that may explain the variability of the slow wind at Earth. But the nature and strength of the turbulence has been hard to quantify because measurements have been limited to in-situ detection of variations in measurable parameters. Remote imaging of comet tails offers a unique opportunity to study the paths of localized "test particles" in the solar wind, and to analyze the motion in the same way that hydrodynamicists might study turbulence in water with test particles. We report on a careful analysis of the motion of 230 individually tracked features in the tail of a comet observed with STEREO/HI-1, which interacted strongly with the solar wind between 0.2 and 0.3 AU during the observation period, and draw deep conclusions about the nature of solar wind variability. Title: RAISE (Rapid Acquisition Imaging Spectrograph Experiment): Results and Instrument Status Authors: Laurent, Glenn T.; Hassler, Donald; DeForest, Craig; Ayres, Tom; Davis, Michael; DePontieu, Bart; Diller, Jed; Graham, Roy; Schule, Udo; Warren, Harry Bibcode: 2015TESS....140203L Altcode: We present initial results from the successful November 2014 launch of the RAISE (Rapid Acquisition Imaging Spectrograph Experiment) sounding rocket program, including intensity maps, high-speed spectroheliograms and dopplergrams, as well as an update on instrument status. The RAISE sounding rocket payload is the fastest high-speed scanning-slit imaging spectrograph flown to date and is designed to observe the dynamics and heating of the solar chromosphere and corona on time scales as short as 100-200ms, with arcsecond spatial resolution and a velocity sensitivity of 1-2 km/s. The instrument is based on a class of UV/EUV imaging spectrometers that use only two reflections to provide quasi-stigmatic performance simultaneously over multiple wavelengths and spatial fields. The design uses an off-axis parabolic telescope mirror to form a real image of the sun on the spectrometer entrance aperture. A slit then selects a portion of the solar image, passing its light onto a near-normal incidence toroidal grating, which re-images the spectrally dispersed radiation onto two array detectors. Two full spectral passbands over the same one-dimensional spatial field are recorded simultaneously with no scanning of the detectors or grating. The two different spectral bands (1st-order 1205-1243Å and 1526-1564Å) are imaged onto two intensified Active Pixel Sensor (APS) detectors whose focal planes are individually adjusted for optimized performance. RAISE reads out the full field of both detectors at 5-10 Hz, allowing us to record over 1,500 complete spectral observations in a single 5-minute rocket flight, opening up a new domain of high time resolution spectral imaging and spectroscopy. RAISE is designed to study small-scale multithermal dynamics in active region (AR) loops, explore the strength, spectrum and location of high frequency waves in the solar atmosphere, and investigate the nature of transient brightenings in the chromospheric network. Title: Status of the SWAMIS Emerging Flux Detection and Feature Tracking Codes Authors: Lamb, Derek A.; DeForest, Craig; Davey, Alisdair R. Bibcode: 2015TESS....140308L Altcode: We describe recent improvements to the SWAMIS magnetic feature tracking code for SDO/HMI data. In particular, we detail recent substantial improvements in the detection of emerging flux regions in near-real-time magnetograms, show detailed examples of the detected events, and report on the status of the code in the HMI analysis pipeline. In addition, we describe some recent improvements in efficiently analyzing full-resolution, full disk HMI magnetograms, and describe our plans for future code development. Title: Spatio-temporal Patterns in Arcsecond-scale Flux Emergence Events Authors: Lamb, Derek A.; DeForest, Craig Bibcode: 2015TESS....111106L Altcode: Active regions’ pattern of magnetic flux emergence across latitude and time has been well described for nearly a century, and is generally understood in the context of the solar cycle. The pattern of emergence at smaller scales is thought to be basically random in space and time. Case studies of certain small-scale emergence events have suggested the possibility that some of these events are related to others in some way: the observations typically show simultaneous emergence events in close proximity to each other, and in some cases also with a similarity in the geometric orientation of the events. Whether these events are merely chance encounters, or signify a subsurface topological connection has not been addressed. Here we present SDO/HMI observations of some case studies of this clustered flux emergence, as well as a catalog of flux emergence events over a short time period, obtained through both manual and automated methods. Finally, we present a preliminary statistical analysis of the flux emergence events to determine whether these are simply an effect of an acute, imaginative human visual system or significantly unlikely to be chance encounters. Title: Chromospheric Rapid Blueshifted Excursions Observed with IBIS and their Association with Photospheric Magnetic Field Evolution Authors: Deng, Na; Chen, Xin; Liu, Chang; Jing, Ju; Tritschler, Alexandra; Reardon, Kevin P.; Lamb, Derek A.; Deforest, Craig E.; Denker, Carsten; Wang, Shuo; Liu, Rui; Wang, Haimin Bibcode: 2015ApJ...799..219D Altcode: 2014arXiv1412.4038D Chromospheric rapid blueshifted excursions (RBEs) are suggested to be the disk counterparts of type II spicules at the limb and believed to contribute to the coronal heating process. Previous identification of RBEs was mainly based on feature detection using Dopplergrams. In this paper, we study RBEs on 2011 October 21 in a very quiet region at the disk center, which were observed with the high-cadence imaging spectroscopy of the Ca II 8542 Å line from the Interferometric Bidimensional Spectrometer (IBIS). By using an automatic spectral analysis algorithm, a total of 98 RBEs are identified during an 11 minute period. Most of these RBEs have either a round or elongated shape, with an average area of 1.2 arcsec2. The detailed temporal evolution of spectra from IBIS makes possible a quantitative determination of the velocity (~16 km s-1) and acceleration (~400 m s-2) of Ca II 8542 RBEs, and reveals an additional deceleration (~-160 m s-2) phase that usually follows the initial acceleration. In addition, we also investigate the association of RBEs with the concomitant photospheric magnetic field evolution, using coordinated high-resolution and high-sensitivity magnetograms made by Hinode. Clear examples are found where RBEs appear to be associated with the preceding magnetic flux emergence and/or the subsequent flux cancellation. However, further analysis with the aid of the Southwest Automatic Magnetic Identification Suite does not yield a significant statistical association between these RBEs and magnetic field evolution. We discuss the implications of our results in the context of understanding the driving mechanism of RBEs. Title: Observations of a Solar Wind Domain Boundary Extending 1 AU from the Sun Authors: Howard, T. A.; DeForest, C. E. Bibcode: 2015ApJ...800L..25H Altcode: We present measurements of a spatially coherent structure that extended over 0.5 AU through the solar wind. This is the first observation of such a feature in white light, and it is rare, possibly unique. While we cannot present conclusive evidence of its origin and nature, we speculate, based on white-light observation and measurement, that it is a domain boundary between fast and slow solar wind streams, possibly arising from the flank of a coronal mass ejection that erupted some 10 hr prior to its appearance. The puzzling aspect of this feature is that it maintained its structural integrity for several days in the solar wind at distances near 1 AU, yet it showed no signs of turbulent break up. This is despite an expectation, which we derive from basic hydrodynamic theory, that turbulence induced by the Kelvin-Helmholtz instability should at least be present there. We present our observations, measurements, and speculations and conclude with an appeal to the wider community for suggestions as to the source, nature, and uniqueness of this feature. Title: Instant: An Innovative L5 Small Mission Concept for Coordinated Science with Solar Orbiter and Solar Probe Plus Authors: Lavraud, B.; Liu, Y. D.; Harrison, R. A.; Liu, W.; Auchere, F.; Gan, W.; Lamy, P. L.; Xia, L.; Eastwood, J. P.; Wimmer-Schweingruber, R. F.; Zong, Q.; Rochus, P.; Maksimovic, M.; Temmer, M.; Escoubet, C. P.; Kilpua, E.; Rouillard, A. P.; Davies, J. A.; Vial, J. C.; Gopalswamy, N.; Bale, S. D.; Li, G.; Howard, T. A.; DeForest, C. E. Bibcode: 2014AGUFMSH21B4109L Altcode: We will present both the science objectives and related instrumentation of a small solar and heliospheric mission concept, INSTANT: INvestigation of Solar-Terrestrial Activity aNd Transients. It will be submitted as an opportunity to the upcoming ESA-China S-class mission call later this year. This concept was conceived to allow innovative measurements and unprecedented, early determination of key properties of Earthbound CMEs from the L5 vantage point. Innovative measurements will include magnetic field determination in the corona thanks to Hanle measurement in Lyman-α and polarized heliospheric imaging for accurate determination of CME trajectories. With complementary in situ measurements, it will uniquely permit solar storm science, solar storm surveillance, and synergy with Solar Orbiter and Solar Probe Plus (the ESA-China S2 mission launch is planned in 2021). Title: Magnetic Feature Tracking in the SDO Era: Past Sacrifices, Recent Advances, and Future Possibilities Authors: Lamb, D. A.; DeForest, C. E.; Van Kooten, S. Bibcode: 2014AGUFMSH34A..01L Altcode: When implementing computer vision codes, a common reaction to the high angular resolution and the high cadence of SDO's image products has been to reduce the resolution and cadence of the data so that it "looks like" SOHO data. This can be partially justified on physical grounds: if the phenomenon that a computer vision code is trying to detect was characterized in low-resolution, low cadence data, then the higher quality data may not be needed. But sacrificing at least two, and sometimes all four main advantages of SDO's imaging data (the other two being a higher duty cycle and additional data products) threatens to also discard the perhaps more subtle discoveries waiting to be made: a classic baby-with-the-bath-water situation. In this presentation, we discuss some of the sacrifices made in implementing SWAMIS-EF, an automatic emerging magnetic flux region detection code for SDO/HMI, and how those sacrifices simultaneously simplified and complicated development of the code. SWAMIS-EF is a feature-finding code, and we will describe some situations and analyses in which a feature-finding code excels, and some in which a different type of algorithm may produce more favorable results. In particular, because the solar magnetic field is irreducibly complex at the currently observed spatial scales, searching for phenomena such as flux emergence using even semi-strict physical criteria often leads to large numbers of false or missed detections. This undesirable behavior can be mitigated by relaxing the imposed physical criteria, but here too there are tradeoffs: decreased numbers of missed detections may increase the number of false detections if the selection criteria are not both sensitive and specific to the searched-for phenomenon. Finally, we describe some recent steps we have taken to overcome these obstacles, by fully embracing the high resolution, high cadence SDO data, optimizing and partially parallelizing our existing code as a first step to allow fast magnetic feature tracking of full resolution HMI magnetograms. Even with the above caveats, if used correctly such a tool can provide a wealth of information on the positions, motions, and patterns of features, enabling large, cross-scale analyses that can answer important questions related to the solar dynamo and to coronal heating. Title: New Platforms for Suborbital Astronomical Observations and In Situ Atmospheric Measurements: Spacecraft, Instruments, and Facilities Authors: Rodway, K.; DeForest, C. E.; Diller, J.; Vilas, F.; Sollitt, L. S.; Reyes, M. F.; Filo, A. S.; Anderson, E. Bibcode: 2014AGUFMSH52B..06R Altcode: Suborbital astronomical observations have over 50 years' history using NASA's sounding rockets and experimental space planes. The new commercial space industry is developing suborbital reusable launch vehicles (sRLV's) to provide low-cost, flexible, and frequent access to space at ~100 km altitude. In the case of XCOR Aerospace's Lynx spacecraft, the vehicle design and capabilities work well for hosting specially designed experiments that can be flown with a human-tended researcher or alone with the pilot on a customized mission. Some of the first-generation instruments and facilities that will conduct solar observations on dedicated Lynx science missions include the SwRI Solar Instrument Pointing Platform (SSIPP) and Atsa Suborbital Observatory, as well as KickSat sprites, which are picosatellites for in situ atmospheric and solar phenomena measurements. The SSIPP is a demonstration two-stage pointed solar observatory that operates inside the Lynx cockpit. The coarse pointing stage includes the pilot in the feedback loop, and the fine stage stabilizes the solar image to achieve arcsecond class pointing. SSIPP is a stepping-stone to future external instruments that can operate with larger apertures and shorter wavelengths in the solar atmosphere. The Planetary Science Institute's Atsa Suborbital Observatory combines the strengths of ground-based observatories and space-based observing to create a facility where a telescope is maintained and used interchangeably with either in-house facility instruments or user-provided instruments. The Atsa prototype is a proof of concept, hand-guided camera that mounts on the interior of the Lynx cockpit to test target acquisition and tracking for human-operated suborbital astronomy. KickSat sprites are mass-producible, one inch printed circuit boards (PCBs) populated by programmable off the shelf microprocessors and radios for real time data transmission. The sprite PCBs can integrate chip-based radiometers, magnetometers, accelerometers, etc. This low-cost, customizable platform provides researchers the ability to design immediately responsive, repeatable, high resolution experiments. Title: The Distribution and Behaviour of Photospheric Magnetic Features Authors: Parnell, C. E.; Lamb, D. A.; DeForest, C. E. Bibcode: 2014AGUFMSH34A..05P Altcode: Over the past two decades enormous amounts of data on the magnetic fields of the solar photosphere have been produced by both ground-based (Kitt Peak & SOLIS), as well as space-based instruments (MDI, Hinode & HMI). In order to study the behaviour and distribution of photospheric magnetic features, efficient automated detection routines need to be utilised to identify and track magnetic features. In this talk, I will discuss the pros and cons of different automated magnetic feature identification and tracking routines with a special focus on the requirements of these codes to deal with the large data sets produced by HMI. By patching together results from Hinode and MDI (high-res & full-disk), the fluxes of magnetic features were found to follow a power-law over 5 orders of magnitude. At the strong flux tail of this distribution, the power law was found to fall off at solar minimum, but was maintained over all fluxes during solar maximum. However, the point of deflection in the power-law distribution occurs at a patching point between instruments and so questions remain over the reasons for the deflection. The feature fluxes determined from the superb high-resolution HMI data covers almost all of the 5 orders of magnitude. Considering both solar mimimum and solar maximum HMI data sets, we investigate whether the power-law over 5 orders of magnitude in flux still holds. Furthermore, we investigate the behaviour of magnetic features in order to probe the nature of their origin. In particular, we analyse small-scale flux emergence events using HMI data to investigate the existence of a small-scale dynamo just below the solar photosphere. Title: DELPHI: A Pathfinder to LCAS on board the International Space Station Authors: DeForest, C. E.; Howard, T. A.; Laurent, G. T.; Diller, J. Bibcode: 2014AGUFMSH53B4232D Altcode: NASA's venerable LCAS sounding rocket program has been the primary means to test new space instrumentation for space physics, for over 60 years. Recently, new LCAS pathways have been introduced for instruments and science that require longer exposure than a sounding rocket affords. The International Space Station (ISS) offers similar infrastructure to a sounding rocket, with ample mass and volume, controlled attitude, and predefined and generous power and telemetry interfaces. The DEmonstration LEO Polarizing Heliospheric Imager is an LCAS mission that pioneers replacing the SPARCS+black brant stack with the ISS itself, to exploit the environment afforded by the ISS and demonstrate new instrumentation on-orbit. DELPHI is a solar off-pointed heliospheric imager that demonstrates the use of pB/B and quantitative photometry to locate solar wind features in 3-D with high spatial resolution, in a few-month mission. It makes use of the stable environment and high telemetry volume (1Mbps) on ISS to improve image quality with ground postprocessing. It is built on the ISS-standard ExPA interface and robotically deployed from the Space-X Dragon trunk to an external mount location. We will discuss some of the engineering and programmatic trades go with designing an orbital sounding-rocket-class instrument, and advocate using ISS as a future platform for instrument development. Title: The Pre- and Post-Launch Configuration of a CME Flux Rope Authors: Howard, T. A.; DeForest, C. E. Bibcode: 2014AGUFMSH13A4082H Altcode: While the standard picture of a coronal mass ejection (CME) remains largely unchanged from the early 1990s, we continue to develop our understanding of the finer structures comprising the CME anatomy. Our efforts are impeded by an assortment of inconveniences involving the detection and tracking of CMEs: namely that they are two-dimensional manifestations of an extended three-dimensional structure, they are optically-thin, have asymmetric geometries that evolve at different kinematic rates, and when observed by coronagraphs their appearances are subject to the laws of Thomson scattering. Even in the STEREO era we have rarely had an opportunity to explore in 3-D the finer structures comprising CMEs and their greater counterparts. Through careful analysis of a CME observed during such an opportunity, we have constructed a detailed narrative describing the pre-launch configuration of the magnetic configuration that gave rise to the CME, and its launch and evolution through the corona and solar wind. We present our narrative using observational evidence from EUV imagers, coronagraphs and heliospheric imagers. We offer insight into the implications of its 3-D structure for CME observation, including the difficulties presented by geometry, kinematics and Thomson scattering. Title: Hi-C Observations and the Structure of Coronal Loops Authors: DeForest, C. E.; Klimchuk, J. A. Bibcode: 2014AGUFMSH31C..04D Altcode: Despite nearly four decades of study since the launch of Skylab, the physical structure of coronal loops remains an enigma. Loops are guided by the magnetic field and, in the common EUV emission lines, appear to be composed of stranded structures reminiscent of field lines. This stranded structure appears to have constant or nearly-constant width, at odds with naive understanding of flux tube behavior in a field gradient. Possible explanations range from physical solutions such as twisted magnetic structure or peculiar properties of separators and quasi-separators, to observation effects that invoke finite resolution or anisotropy of the field containing each strand. The uncertainty affects many aspects of basic coronal physics, because some of the possible explanations for stranded structure have strong implications for other mysteries such as the anomalously tall scale height of the EUV corona. The Hi-C EUV images are the highest resolution coronal images to date, and offer new insights into the structure of coronal loops. We present an overview of research to date, show results from a detailed analysis of several dozen well-presented loops that are visible in the Hi-C data set, and speculate on the implications for the rest of the corona. Title: The High-Resolution Coronal Imager (Hi-C) Authors: Kobayashi, Ken; Cirtain, Jonathan; Winebarger, Amy R.; Korreck, Kelly; Golub, Leon; Walsh, Robert W.; De Pontieu, Bart; DeForest, Craig; Title, Alan; Kuzin, Sergey; Savage, Sabrina; Beabout, Dyana; Beabout, Brent; Podgorski, William; Caldwell, David; McCracken, Kenneth; Ordway, Mark; Bergner, Henry; Gates, Richard; McKillop, Sean; Cheimets, Peter; Platt, Simon; Mitchell, Nick; Windt, David Bibcode: 2014SoPh..289.4393K Altcode: 2014SoPh..tmp..104K The High-Resolution Coronal Imager (Hi-C) was flown on a NASA sounding rocket on 11 July 2012. The goal of the Hi-C mission was to obtain high-resolution (≈ 0.3 - 0.4''), high-cadence (≈ 5 seconds) images of a solar active region to investigate the dynamics of solar coronal structures at small spatial scales. The instrument consists of a normal-incidence telescope with the optics coated with multilayers to reflect a narrow wavelength range around 19.3 nm (including the Fe XII 19.5-nm spectral line) and a 4096×4096 camera with a plate scale of 0.1'' pixel−1. The target of the Hi-C rocket flight was Active Region 11520. Hi-C obtained 37 full-frame images and 86 partial-frame images during the rocket flight. Analysis of the Hi-C data indicates the corona is structured on scales smaller than currently resolved by existing satellite missions. Title: The Formation and Launch of a Coronal Mass Ejection Flux Rope: A Narrative Based on Observations Authors: Howard, T. A.; DeForest, C. E. Bibcode: 2014ApJ...796...33H Altcode: We present a data-driven narrative of the launch and early evolution of the magnetic structure that gave rise to the coronal mass ejection (CME) on 2008 December 12. The structure formed on December 7 and launched early on December 12. We interpret this structure as a flux rope based on prelaunch morphology, postlaunch magnetic measurements, and the lack of large-scale magnetic reconnection signatures at launch. We ascribe three separate onset mechanisms to the complete disconnection of the flux rope from the Sun. It took 19 hr for the flux rope to be fully removed from the Sun, by which time the segment that first disconnected was around 40 R ⊙ away. This implies that the original flux rope was stretched or broken; we provide evidence for a possible bisection. A transient dark arcade was observed on the Sun that was later obscured by a bright arcade, which we interpret as the strapping field stretching and magnetically reconnecting as it disconnected from the coronal field. We identify three separate structures in coronagraph images to be manifestations of the same original flux rope, and we describe the implications for CME interpretation. We cite the rotation in the central flux rope vector of the magnetic clouds observed in situ by ACE/Wind and STEREO-B as evidence of the kink instability of the eastern segment of the flux rope. Finally, we discuss possible alternative narratives, including multiple prelaunch magnetic structures and the nonflux rope scenario. Our results support the view that, in at least some CMEs, flux rope formation occurs before launch. Title: Spatial Nonlocality of the Small-scale Solar Dynamo Authors: Lamb, D. A.; Howard, T. A.; DeForest, C. E. Bibcode: 2014ApJ...788....7L Altcode: 2014arXiv1404.3259L We explore the nature of the small-scale solar dynamo by tracking magnetic features. We investigate two previously explored categories of the small-scale solar dynamo: shallow and deep. Recent modeling work on the shallow dynamo has produced a number of scenarios for how a strong network concentration can influence the formation and polarity of nearby small-scale magnetic features. These scenarios have measurable signatures, for which we test using magnetograms from the Narrowband Filter Imager (NFI) on board Hinode. We find no statistical tendency for newly formed magnetic features to cluster around or away from network concentrations, nor do we find any statistical relationship between their polarities. We conclude that there is no shallow or "surface" dynamo on the spatial scales observable by Hinode/NFI. In light of these results, we offer a scenario in which the subsurface field in a deep solar dynamo is stretched and distorted via turbulence, allowing the small-scale field to emerge at random locations on the photosphere. Title: The Turbulent Origin of the Slow Solar Wind Authors: DeForest, Craig; Matthaeus, Bill; Howard, Tim A. Bibcode: 2014AAS...22432363D Altcode: We report on preliminary analyses of early solar wind turbulence via heliospheric imaging: both the brightness structure function in the STEREO-A HI-1 field of view and paths taken by individual boli of comet-tail material in the solar wind. The analyses are complementary and preliminary results indicate that turbulent processing is underway even within the early HI-1 field of view (as low as 20-30 Rs). Title: Inbound Waves in the Solar Corona: A Direct Indicator of Alfvén Surface Location Authors: DeForest, C. E.; Howard, T. A.; McComas, D. J. Bibcode: 2014ApJ...787..124D Altcode: 2014arXiv1404.3235D The tenuous supersonic solar wind that streams from the top of the corona passes through a natural boundary—the Alfvén surface—that marks the causal disconnection of individual packets of plasma and magnetic flux from the Sun itself. The Alfvén surface is the locus where the radial motion of the accelerating solar wind passes the radial Alfvén speed, and therefore any displacement of material cannot carry information back down into the corona. It is thus the natural outer boundary of the solar corona and the inner boundary of interplanetary space. Using a new and unique motion analysis to separate inbound and outbound motions in synoptic visible-light image sequences from the COR2 coronagraph on board the STEREO-A spacecraft, we have identified inbound wave motion in the outer corona beyond 6 solar radii for the first time and used it to determine that the Alfvén surface is at least 12 solar radii from the Sun over the polar coronal holes and 15 solar radii in the streamer belt, well beyond the distance planned for NASA's upcoming Solar Probe Plus mission. To our knowledge, this is the first measurement of inbound waves in the outer solar corona and the first direct measurement of lower bounds for the Alfvén surface. Title: Observing MHD Waves in the Solar Wind Acceleration Region Authors: DeForest, Craig; McComas, Dave; Howard, Tim A. Bibcode: 2014AAS...22440801D Altcode: We have, for the first time, observed and characterized compressive waves propagating both outward and inward in the outer solar corona above 4 Rs. In addition to detecting the waves, we have used them to measure outflow in the all-important wind acceleration region. Because the corona is an MHD system, any disturbance in the corona launches low-frequency waves that propagate at the familiar MHD speeds and serve to communicate that disturbance to other parts of the system. Through careful filtration of synoptic STEREO-A/COR-2 data, we have been able to measure both inbound and outbound waves at all locations in the solar corona. By measuring in/out asymmetries in the wave characteristics we have been able to estimate the solar wind acceleration profile. Further, we are able to estimate the location of the Alfvén surface - the hard-to-measure transition between the corona and the superalfvénic solar wind, and the boundary at which solar magnetic field lines transition from "closed" to "open". There is a great deal of work to be done beyond these preliminary results, which - it is hoped - open a new avenue for understanding coronal dynamics and the origin of the solar wind. Title: Sparkling Extreme-ultraviolet Bright Dots Observed with Hi-C Authors: Régnier, S.; Alexander, C. E.; Walsh, R. W.; Winebarger, A. R.; Cirtain, J.; Golub, L.; Korreck, K. E.; Mitchell, N.; Platt, S.; Weber, M.; De Pontieu, B.; Title, A.; Kobayashi, K.; Kuzin, S.; DeForest, C. E. Bibcode: 2014ApJ...784..134R Altcode: 2014arXiv1402.2457R Observing the Sun at high time and spatial scales is a step toward understanding the finest and fundamental scales of heating events in the solar corona. The high-resolution coronal (Hi-C) instrument has provided the highest spatial and temporal resolution images of the solar corona in the EUV wavelength range to date. Hi-C observed an active region on 2012 July 11 that exhibits several interesting features in the EUV line at 193 Å. One of them is the existence of short, small brightenings "sparkling" at the edge of the active region; we call these EUV bright dots (EBDs). Individual EBDs have a characteristic duration of 25 s with a characteristic length of 680 km. These brightenings are not fully resolved by the SDO/AIA instrument at the same wavelength; however, they can be identified with respect to the Hi-C location of the EBDs. In addition, EBDs are seen in other chromospheric/coronal channels of SDO/AIA, which suggests a temperature between 0.5 and 1.5 MK. Based on their frequency in the Hi-C time series, we define four different categories of EBDs: single peak, double peak, long duration, and bursty. Based on a potential field extrapolation from an SDO/HMI magnetogram, the EBDs appear at the footpoints of large-scale, trans-equatorial coronal loops. The Hi-C observations provide the first evidence of small-scale EUV heating events at the base of these coronal loops, which have a free magnetic energy of the order of 1026 erg. Title: The Future of Heliospheric Imaging Authors: DeForest, Craig Bibcode: 2014cosp...40E.659D Altcode: Heliospheric Imaging uses Thomson scattering to image structures in the solar wind plasma, revealing morphology and total density of features that previously were visible only through a combination of imagination and inference from a few timeseries of in-situ measurements. With the first successful routine, quantitative imaging of solar wind features by emph{STEREO}/HI it is time to consider the next generation of heliospheric imaging instruments to improve and exploit the techniques opened by STEREO. Higher sensitivity, higher resolution, and polarization measurements are obvious desiderata. Further, each heliospheric imaging instrument built to date has revealed surprising and counter-intuitive limitations and advantages of particular techniques. I will summarize important lessons learned from past and current heliospheric imaging instruments, directions in which those instruments can and should be improved, and ideas for the next generation of imagers. Title: Understanding CME Propagation through Combined Imaging and In-Situ Measurements Authors: DeForest, Craig; Howard, Timothy Bibcode: 2014cosp...40E.658D Altcode: NASA's STEREO mission is the first observatory to track CMEs approximately continuously from their pre-initiation state in the corona to impact with in-situ probes near 1 AU from the Sun, via direct imaging of Thomson-scattered light. This affords positive identification of structures detected in-situ, with particular features in the pre-eruption solar corona. It also permits, for the first time, direct observation of the morphology and evolution of CMEs as they propagate and interact with the surrounding media in interplanetary space. We report on recent results obtained by tracking CMEs and other ejecta from the corona to impact with in-situ probes, discuss their importance to understanding the relationship between solar activity and geospace events, and present ideas for future measurements to improve on these results. Title: Asymmetry of the Mars Ionosphere Boundary Altitude during a Solar Energetic Particle Event Authors: Frahm, R. A.; Elliott, H. A.; Winningham, J. D.; Sharber, J. R.; DeForest, C. E.; Howard, T. A.; Kallio, E. J.; McKenna-Lawlor, S.; Duru, F.; Morgan, D. D.; Coates, A. J.; Odstrcil, D.; Lundin, R. N.; Futaana, Y.; Barabash, S. V. Bibcode: 2013AGUFM.P21A1712F Altcode: The Electron Spectrometer (ELS) and the Ion Mass Spectrometer (IMA) from the Analyzer of Space Plasmas and Energetic Atoms (ASPERA-3) experiment on the ESA's Mars Express (MEx) spacecraft have been used to study a Solar Energetic Particle (SEP) event associated with a Class X solar flare on on January 27, 2012. Arrival of the SEP at Mars about 46 minutes later is observed as an increase in the background of these plasma instruments. The background counts were observed to increase sharply, followed by a gradual decrease that lasted for about 4 days. During this time, ELS and IMA also recorded passages across the Martian ionospheric boundary on the dusk side of the planet, twice during each MEx orbit. The altitude of the ionospheric boundary was thereby found to have behaved differently in the northern and southern hemispheres. The boundary increased in altitude in each hemisphere with a time delay as the flare pumped energy into the Mars system. After reaching peak altitude, the ionospheric boundary returned to its original configuration faster in the northern than in the southern hemisphere. This suggests that the main difference between the northern and southern hemispheres at Mars, namely the presence in the south of crustal magnetic fields, is responsible for the dissipation of the energy input at a slower rate in the southern than in the northern hemisphere. Title: Anti-parallel EUV Flows Observed along Active Region Filament Threads with Hi-C Authors: Alexander, Caroline E.; Walsh, Robert W.; Régnier, Stéphane; Cirtain, Jonathan; Winebarger, Amy R.; Golub, Leon; Kobayashi, Ken; Platt, Simon; Mitchell, Nick; Korreck, Kelly; DePontieu, Bart; DeForest, Craig; Weber, Mark; Title, Alan; Kuzin, Sergey Bibcode: 2013ApJ...775L..32A Altcode: 2013arXiv1306.5194A Plasma flows within prominences/filaments have been observed for many years and hold valuable clues concerning the mass and energy balance within these structures. Previous observations of these flows primarily come from Hα and cool extreme-ultraviolet (EUV) lines (e.g., 304 Å) where estimates of the size of the prominence threads has been limited by the resolution of the available instrumentation. Evidence of "counter-steaming" flows has previously been inferred from these cool plasma observations, but now, for the first time, these flows have been directly imaged along fundamental filament threads within the million degree corona (at 193 Å). In this work, we present observations of an AR filament observed with the High-resolution Coronal Imager (Hi-C) that exhibits anti-parallel flows along adjacent filament threads. Complementary data from the Solar Dynamics Observatory (SDO)/Atmospheric Imaging Assembly (AIA) and Helioseismic and Magnetic Imager are presented. The ultra-high spatial and temporal resolution of Hi-C allow the anti-parallel flow velocities to be measured (70-80 km s-1) and gives an indication of the resolvable thickness of the individual strands (0.''8 ± 0.''1). The temperature of the plasma flows was estimated to be log T (K) = 5.45 ± 0.10 using Emission Measure loci analysis. We find that SDO/AIA cannot clearly observe these anti-parallel flows or measure their velocity or thread width due to its larger pixel size. We suggest that anti-parallel/counter-streaming flows are likely commonplace within all filaments and are currently not observed in EUV due to current instrument spatial resolution. Title: Decline and Recovery of the Interplanetary Magnetic Field during the Protracted Solar Minimum Authors: Smith, Charles W.; Schwadron, Nathan A.; DeForest, Craig E. Bibcode: 2013ApJ...775...59S Altcode: The interplanetary magnetic field (IMF) is determined by the amount of solar magnetic flux that passes through the top of the solar corona into the heliosphere, and by the dynamical evolution of that flux. Recently, it has been argued that the total flux of the IMF evolves over the solar cycle due to a combination of flux that extends well outside of 1 AU and is associated with the solar wind, and additionally, transient flux associated with coronal mass ejections (CMEs). In addition to the CME eruption rate, there are three fundamental processes involving conversion of magnetic flux (from transient to wind-associated), disconnection, and interchange reconnection that control the levels of each form of magnetic flux in the interplanetary medium. This is distinct from some earlier models in which the wind-associated component remains steady across the solar cycle. We apply the model of Schwadron et al. that quantifies the sources, interchange, and losses of magnetic flux to 50 yr of interplanetary data as represented by the Omni2 data set using the sunspot number as a proxy for the CME eruption rate. We do justify the use of that proxy substitution. We find very good agreement between the predicted and observed interplanetary magnetic flux. In the absence of sufficient CME eruptions, the IMF falls on the timescale of ~6 yr. A key result is that rising toroidal flux resulting from CME eruption predates the increase in wind-associated IMF. Title: Solar Magnetic Tracking. IV. The Death of Magnetic Features Authors: Lamb, D. A.; Howard, T. A.; DeForest, C. E.; Parnell, C. E.; Welsch, B. T. Bibcode: 2013ApJ...774..127L Altcode: 2013arXiv1307.4019L The removal of magnetic flux from the quiet-Sun photosphere is important for maintaining the statistical steady state of the magnetic field there, for determining the magnetic flux budget of the Sun, and for estimating the rate of energy injected into the upper solar atmosphere. Magnetic feature death is a measurable proxy for the removal of detectable flux, either by cancellation (submerging or rising loops, or reconnection in the photosphere) or by dispersal of flux. We used the SWAMIS feature tracking code to understand how nearly 2 × 104 magnetic features die in an hour-long sequence of Hinode/SOT/NFI magnetograms of a region of the quiet Sun. Of the feature deaths that remove visible magnetic flux from the photosphere, the vast majority do so by a process that merely disperses the previously detected flux so that it is too small and too weak to be detected, rather than completely eliminating it. The behavior of the ensemble average of these dispersals is not consistent with a model of simple planar diffusion, suggesting that the dispersal is constrained by the evolving photospheric velocity field. We introduce the concept of the partial lifetime of magnetic features, and show that the partial lifetime due to Cancellation of magnetic flux, 22 hr, is three times slower than previous measurements of the flux turnover time. This indicates that prior feature-based estimates of the flux replacement time may be too short, in contrast with the tendency for this quantity to decrease as resolution and instrumentation have improved. This suggests that dispersal of flux to smaller scales is more important for the replacement of magnetic fields in the quiet Sun than observed bipolar cancellation. We conclude that processes on spatial scales smaller than those visible to Hinode dominate the processes of flux emergence and cancellation, and therefore also the quantity of magnetic flux that threads the photosphere. Title: Structure of solar coronal loops: from miniature to large-scale Authors: Peter, H.; Bingert, S.; Klimchuk, J. A.; de Forest, C.; Cirtain, J. W.; Golub, L.; Winebarger, A. R.; Kobayashi, K.; Korreck, K. E. Bibcode: 2013A&A...556A.104P Altcode: 2013arXiv1306.4685P
Aims: We use new data from the High-resolution Coronal Imager (Hi-C) with its unprecedented spatial resolution of the solar corona to investigate the structure of coronal loops down to 0.2''.
Methods: During a rocket flight, Hi-C provided images of the solar corona in a wavelength band around 193 Å that is dominated by emission from Fe xii showing plasma at temperatures around 1.5 MK. We analyze part of the Hi-C field-of-view to study the smallest coronal loops observed so far and search for the possible substructuring of larger loops.
Results: We find tiny 1.5 MK loop-like structures that we interpret as miniature coronal loops. Their coronal segments above the chromosphere have a length of only about 1 Mm and a thickness of less than 200 km. They could be interpreted as the coronal signature of small flux tubes breaking through the photosphere with a footpoint distance corresponding to the diameter of a cell of granulation. We find that loops that are longer than 50 Mm have diameters of about 2'' or 1.5 Mm, which is consistent with previous observations. However, Hi-C really resolves these loops with some 20 pixels across the loop. Even at this greatly improved spatial resolution, the large loops seem to have no visible substructure. Instead they show a smooth variation in cross-section.
Conclusions: That the large coronal loops do not show a substructure on the spatial scale of 0.1'' per pixel implies that either the densities and temperatures are smoothly varying across these loops or it places an upper limit on the diameter of the strands the loops might be composed of. We estimate that strands that compose the 2'' thick loop would have to be thinner than 15 km. The miniature loops we find for the first time pose a challenge to be properly understood through modeling.

Appendices are available in electronic form at http://www.aanda.org Title: STEREO/SECCHI Level 2 Heliospheric Data: Status and Availability Authors: DeForest, Craig; Howard, T. A. Bibcode: 2013SPD....44..132D Altcode: We are currently processing the STEREO/SECCHI heliospheric imaging data to separate the starfield, and depositing them into the SDAC and STEREO data repository. We present an overview of the data, the quality, how to use (and how not to overinterpret) them scientifically, and status of the processing project.Abstract (2,250 Maximum Characters): We are currently processing the STEREO/SECCHI heliospheric imaging data to separate the starfield, and depositing them into the SDAC and STEREO data repository. We present an overview of the data, the quality, how to use (and how not to overinterpret) them scientifically, and status of the processing project. Title: Detecting Nanoflare Heating Events in Subarcsecond Inter-moss Loops Using Hi-C Authors: Winebarger, Amy R.; Walsh, Robert W.; Moore, Ronald; De Pontieu, Bart; Hansteen, Viggo; Cirtain, Jonathan; Golub, Leon; Kobayashi, Ken; Korreck, Kelly; DeForest, Craig; Weber, Mark; Title, Alan; Kuzin, Sergey Bibcode: 2013ApJ...771...21W Altcode: The High-resolution Coronal Imager (Hi-C) flew aboard a NASA sounding rocket on 2012 July 11 and captured roughly 345 s of high-spatial and temporal resolution images of the solar corona in a narrowband 193 Å channel. In this paper, we analyze a set of rapidly evolving loops that appear in an inter-moss region. We select six loops that both appear in and fade out of the Hi-C images during the short flight. From the Hi-C data, we determine the size and lifetimes of the loops and characterize whether these loops appear simultaneously along their length or first appear at one footpoint before appearing at the other. Using co-aligned, co-temporal data from multiple channels of the Atmospheric Imaging Assembly on the Solar Dynamics Observatory, we determine the temperature and density of the loops. We find the loops consist of cool (~105 K), dense (~1010 cm-3) plasma. Their required thermal energy and their observed evolution suggest they result from impulsive heating similar in magnitude to nanoflares. Comparisons with advanced numerical simulations indicate that such dense, cold and short-lived loops are a natural consequence of impulsive magnetic energy release by reconnection of braided magnetic field at low heights in the solar atmosphere. Title: Remotely Measuring Features in the Solar Wind Using Polarimetry Authors: Howard, Tim A.; DeForest, C.; Odstrcil, D. Bibcode: 2013SPD....44..124H Altcode: The theory of Thomson scattering, while well understood when applied to features observed in the corona, has been misunderstood by many when applied to features in the heliosphere. The confusion arises when assumptions applied to analyzing coronagraph data are extended to heliospheric imagers, where the consequences of the theory are somewhat different. Two crucial problems are the assumption of close proximity to the Thomson surface and detectability being governed by the background F and K corona. We demonstrate that these assumptions do not apply to heliospheric imagers. Further, we explore polarized heliospheric imaging in the context of transient feature detection. We show that not only are features detectable above the background, but also that additional information on transients such as coronal mass ejections can be extracted from a combination of polarized and unpolarized images than from unpolarized imaging alone.Abstract (2,250 Maximum Characters): The theory of Thomson scattering, while well understood when applied to features observed in the corona, has been misunderstood by many when applied to features in the heliosphere. The confusion arises when assumptions applied to analyzing coronagraph data are extended to heliospheric imagers, where the consequences of the theory are somewhat different. Two crucial problems are the assumption of close proximity to the Thomson surface and detectability being governed by the background F and K corona. We demonstrate that these assumptions do not apply to heliospheric imagers. Further, we explore polarized heliospheric imaging in the context of transient feature detection. We show that not only are features detectable above the background, but also that additional information on transients such as coronal mass ejections can be extracted from a combination of polarized and unpolarized images than from unpolarized imaging alone. Title: The Launch and Early Evolution of a CME Flux Rope Authors: Howard, Tim A.; DeForest, C. Bibcode: 2013SPD....44...14H Altcode: We present a narrative of the launch and early evolution of a flux rope comprised within the coronal mass ejection (CME) that left the Sun on 12 December 2008. The two STEREO spacecraft were near quadrature at that time, so we were afforded a unique view of this flux rope from along its edge and down its barrel simultaneously using STEREO's EUVI cameras. We find that a sequence of seemingly separate CMEs observed in the corona and solar wind were actually manifestations of the same flux rope passing through the imagers' fields of view at different times. The launch begins with a small solar flare at the northern-most end of a pre-formed flux rope, which lifts off from this end first via the tether-cutting mechanism. Other segments of the flux rope follow this launch, and a filament is observed to roll over the top of these segments and pour back into the solar disk, thereby indicating the mass draining mechanism at play. The southern end of the flux rope remains fixed to the Sun, leading to an eventual stress-fracture and bisection of the flux rope. The severed southern end eventually disconnects from the Sun a day later via what appears to be the kink instability mechanism. This narrative, describing the interplay between three separate onset mechanisms for simple CME during a period of extremely low solar activity, demonstrates the complexity of the physics of CME onset. Title: Imaging the Inner Boundary of the Solar Wind Authors: DeForest, Craig; Howard, T. A.; Matthaeus, W. H. Bibcode: 2013SPD....44..131D Altcode: We have begun analyzing photometric background-subtracted images from STEREO/SECCHI's HI-1 instrument. The images show a clear "flocculated" pattern to the solar wind that is reminiscent of more familiar turbulent flows and more uniformly structured than the top of the corona seen with LASCO C-3 or STEREO/SECCHI COR2. We will present initial quantitative results of this analysis, indicating whether the flocculation pattern is produced locally or advected intact from the corona. This bears heavily on the question of the origin of the variable slow solar wind. Title: Progress toward high resolution EUV spectroscopy Authors: Korendyke, C.; Doschek, G. A.; Warren, H.; Young, P. R.; Chua, D.; Hassler, D. M.; Landi, E.; Davila, J. M.; Klimchuck, J.; Tun, S.; DeForest, C.; Mariska, J. T.; Solar C Spectroscopy Working Group; LEMUR; EUVST Development Team Bibcode: 2013SPD....44..143K Altcode: HIgh resolution EUV spectroscopy is a critical instrumental technique to understand fundamental physical processes in the high temperature solar atmosphere. Spectroscopic observations are used to measure differential emission measure, line of sight and turbulent flows, plasma densities and emission measures. Spatially resolved, spectra of these emission lines with adequate cadence will provide the necessary clues linking small scale structures with large scale, energetic solar phenomena. The necessary observations to determine underlying physical processes and to provide comprehensive temperature coverage of the solar atmosphere above the chromosphere will be obtained by the proposed EUVST instrument for Solar C. This instrument and its design will be discussed in this paper. Progress on the VEry high Resolution Imaging Spectrograph (VERIS) sounding rocket instrument presently under development at the Naval Research Laboratory will also be discussed. Title: Update on SWAMIS Emerging Flux Detection and Magnetic Feature Tracking for SDO/HMI Authors: Lamb, Derek; DeForest, C.; Davey, A. R.; Timmons, R. Bibcode: 2013SPD....44..100L Altcode: The SWAMIS-EF emerging magnetic flux detection algorithm has been operating in the SDO/HMI data pipeline since 2011. We present an update on the status of the module and improvements to the algorithm since it began reporting Emerging Flux HEK events. We will show detailed examples of emerging flux events, and provide some summary information. Finally, we will provide an update on the state of SWAMIS magnetic feature tracking for full-disk, full-resolution HMI line-of-sight magnetograms.Abstract (2,250 Maximum Characters): The SWAMIS-EF emerging magnetic flux detection algorithm has been operating in the SDO/HMI data pipeline since 2011. We present an update on the status of the module and improvements to the algorithm since it began reporting Emerging Flux HEK events. We will show detailed examples of emerging flux events, and provide some summary information. Finally, we will provide an update on the state of SWAMIS magnetic feature tracking for full-disk, full-resolution HMI line-of-sight magnetograms. Title: Status of RAISE, the Rapid Acquisition Imaging Spectrograph Experiment Authors: Laurent, Glenn T.; Hassler, D. M.; DeForest, C.; Ayres, T. R.; Davis, M.; De Pontieu, B.; Schuehle, U.; Warren, H. Bibcode: 2013SPD....44..145L Altcode: The Rapid Acquisition Imaging Spectrograph Experiment (RAISE) sounding rocket payload is a high speed scanning-slit imaging spectrograph designed to observe the dynamics and heating of the solar chromosphere and corona on time scales as short as 100 ms, with 1 arcsec spatial resolution and a velocity sensitivity of 1-2 km/s. The instrument is based on a new class of UV/EUV imaging spectrometers that use only two reflections to provide quasi-stigmatic performance simultaneously over multiple wavelengths and spatial fields. The design uses an off-axis parabolic telescope mirror to form a real image of the sun on the spectrometer entrance aperture. A slit then selects a portion of the solar image, passing its light onto a near-normal incidence toroidal grating, which re-images the spectrally dispersed radiation onto two array detectors. Two full spectral passbands over the same one-dimensional spatial field are recorded simultaneously with no scanning of the detectors or grating. The two different spectral bands (1st-order 1205-1243Å and 1526-1564Å) are imaged onto two intensified Active Pixel Sensor (APS) detectors whose focal planes are individually adjusted for optimized performance. The telescope and grating are coated with B4C to enhance short wavelength (2nd order) reflectance, enabling the instrument to record the brightest lines between 602-622Å and 761-780Å at the same time. RAISE reads out the full field of both detectors at 5-10 Hz, allowing us to record over 1,500 complete spectral observations in a single 5-minute rocket flight, opening up a new domain of high time resolution spectral imaging and spectroscopy. We present an overview of the project, a summary of the maiden flight results, and an update on instrument status.Abstract (2,250 Maximum Characters): The Rapid Acquisition Imaging Spectrograph Experiment (RAISE) sounding rocket payload is a high speed scanning-slit imaging spectrograph designed to observe the dynamics and heating of the solar chromosphere and corona on time scales as short as 100 ms, with 1 arcsec spatial resolution and a velocity sensitivity of 1-2 km/s. The instrument is based on a new class of UV/EUV imaging spectrometers that use only two reflections to provide quasi-stigmatic performance simultaneously over multiple wavelengths and spatial fields. The design uses an off-axis parabolic telescope mirror to form a real image of the sun on the spectrometer entrance aperture. A slit then selects a portion of the solar image, passing its light onto a near-normal incidence toroidal grating, which re-images the spectrally dispersed radiation onto two array detectors. Two full spectral passbands over the same one-dimensional spatial field are recorded simultaneously with no scanning of the detectors or grating. The two different spectral bands (1st-order 1205-1243Å and 1526-1564Å) are imaged onto two intensified Active Pixel Sensor (APS) detectors whose focal planes are individually adjusted for optimized performance. The telescope and grating are coated with B4C to enhance short wavelength (2nd order) reflectance, enabling the instrument to record the brightest lines between 602-622Å and 761-780Å at the same time. RAISE reads out the full field of both detectors at 5-10 Hz, allowing us to record over 1,500 complete spectral observations in a single 5-minute rocket flight, opening up a new domain of high time resolution spectral imaging and spectroscopy. We present an overview of the project, a summary of the maiden flight results, and an update on instrument status. Title: Observations of Synchronous Magnetic Flux Emergence Authors: Lamb, Derek; DeForest, C. Bibcode: 2013SPD....44..106L Altcode: We report on observations of spatially-separated, nearly simultaneous small-scale magnetic flux emergence seen in SDO/HMI magnetograms. In the prototypical event, two pairs of bipoles emerge with a nearly identical north-south orientation, the beginning of the separate emergence events begins within 3 hours of each other, and the distance between the pair is approximately twice the bipolar separation distance. This suggests a common subsurface origin. We present a detailed analysis of this emergence event and the associated evolving coronal magnetic field topology, show other examples of similar events, and present a preliminary statistical analysis of the likelihood of such events occurring by chance. Title: The Onset, Evolution, and Solar Connectivity of a Slow Coronal Mass Ejection Authors: Howard, Tim A.; DeForest, Craig E.; McComas, David J. Bibcode: 2013shin.confE.144H Altcode: We have combined new remote sensing images with near-Earth in-situ datasets to track a complete CME from its onset in the low corona through the inner heliosphere to 1 AU. This CME, observed in December 2008, is slow, and erupted during the lowest activity interval of the last solar minimum. We observe the launch of the initial flux rope and its likely launch mechanisms, identify the magnetic structures both within and surrounding the flux rope, and track their behavior to 1 AU where they are confirmed using solar wind, IMF, and energetic particle in-situ data. We find that the magnetic structure consists of the flux rope core surrounded by layers of fields that are connected to the Sun in a variety of ways. Moving outwards from the core we find a doubly-connected `strapping' field, surrounded by a closed `coronal sheath', which in turn pushes against a draping singly-connected `wind sheath'. All of these structures are observed at 1 AU, indicating that at least for this slow CME the strapping field was stretched out to large distances. Title: Observing Coronal Nanoflares in Active Region Moss Authors: Testa, Paola; De Pontieu, Bart; Martínez-Sykora, Juan; DeLuca, Ed; Hansteen, Viggo; Cirtain, Jonathan; Winebarger, Amy; Golub, Leon; Kobayashi, Ken; Korreck, Kelly; Kuzin, Sergey; Walsh, Robert; DeForest, Craig; Title, Alan; Weber, Mark Bibcode: 2013ApJ...770L...1T Altcode: 2013arXiv1305.1687T The High-resolution Coronal Imager (Hi-C) has provided Fe XII 193Å images of the upper transition region moss at an unprecedented spatial (~0.''3-0.''4) and temporal (5.5 s) resolution. The Hi-C observations show in some moss regions variability on timescales down to ~15 s, significantly shorter than the minute-scale variability typically found in previous observations of moss, therefore challenging the conclusion of moss being heated in a mostly steady manner. These rapid variability moss regions are located at the footpoints of bright hot coronal loops observed by the Solar Dynamics Observatory/Atmospheric Imaging Assembly in the 94 Å channel, and by the Hinode/X-Ray Telescope. The configuration of these loops is highly dynamic, and suggestive of slipping reconnection. We interpret these events as signatures of heating events associated with reconnection occurring in the overlying hot coronal loops, i.e., coronal nanoflares. We estimate the order of magnitude of the energy in these events to be of at least a few 1023 erg, also supporting the nanoflare scenario. These Hi-C observations suggest that future observations at comparable high spatial and temporal resolution, with more extensive temperature coverage, are required to determine the exact characteristics of the heating mechanism(s). Title: The coronal mass ejection interaction with the induced magnetosphere of Mars due to the 27 January 2012 solar storm Authors: Frahm, R. A.; Sharber, J. R.; Winningham, J. D.; Elliott, H. A.; Howard, T. A.; DeForest, C. E.; Odstrĉil, D.; Kallio, E.; McKenna-Lawlor, S.; Barabash, S. Bibcode: 2013AIPC.1539..398F Altcode: An X-class flare on 27 January 2012 generated a high-energy particle stream advancing along the interplanetary magnetic field (IMF) which arrived at Mars in about 39 minutes, with a coronal mass ejection (CME) released from the same active region arriving at Mars several days later. The Electron Spectrometer (ELS), part of the Analyzer of Space Plasmas and Energetic Atoms (ASPERA-3) experiment on the European Mars Express (MEx) Spacecraft, is used to show that the effect of the CME plasma caused an increase in the intensity of the electron distribution function within the Martian magnetosheath. Models of this event predicted the speed, morphology, and Martian impact of the CME. The Mars reaction, being an induced magnetosphere, responds to changes in solar wind conditions by continually self adjusting its magnetosheath to stand off the solar wind. Since the ion component of the solar wind interaction carries momentum away from the Sun, it is the electrons with their significantly greater mobility that must self adjust in order to maintain charge neutrality and the proper induced current flow in order to stand-off changes in the solar wind. Title: Solar energetic particle arrival at Mars due to the 27 January 2012 solar storm Authors: Frahm, R. A.; Sharber, J. R.; Winningham, J. D.; Elliott, H. A.; Howard, T. A.; DeForest, C. E.; Odstrĉil, D.; Kallio, E.; McKenna-Lawlor, S.; Barabash, S. Bibcode: 2013AIPC.1539..394F Altcode: On January 27, 2012, an X-class flare brightened on the Sun at 18:15 UT. This event was associated with the generation of a high-energy stream of Solar Energetic Particles (SEPs) advancing along the Interplanetary Magnetic Field (IMF) which arrived at Mars in about 39 minutes. A Coronal Mass Ejection (CME) arrived at Mars several days later. The Electron Spectrometer (ELS), a part of the Analyzer of Space Plasmas and Energetic Atoms (ASPERA-3) experiment on the European Mars Express (MEx) Spacecraft, associatively detected elevated background levels of penetrating particle radiation which abruptly increased above the baseline level by two orders of magnitude within several hours after first arrival, allowing the particle arrival time to be accurately determined from this gradual SEP. As Mars reacted to the SEP, the atmosphere heated driving expansion of the ionosphere. Title: The Detectability of Features in Unpolarized and Polarized Heliospheric Imagers Authors: Howard, Tim A.; DeForest, Craig E.; Odstrcil, Dusan Bibcode: 2013shin.confE..41H Altcode: We explore the consequences of the theory of Thomson scattering on the detectability of features observed by white light heliospheric imagers. This involves a closer look at the so-called Thomson surface, which represents a sphere describing the locus of points along all lines of sight that are closest to the Sun. We describe how the scattering physics acts to de-emphasize the importance of the Thomson surface to feature detectability, where features are observed with near-equal efficiency across a large range of angles surrounding the surface. This gives rise to what we have termed the `Thomson plateau', and we show how the analysis of features on the plateau is reduced to problems of only density and geometry. Further, we show how the plateau is eliminated when observing in polarized light, and therefore how additional information about features can be extracted using polarimetry rather than unpolarized imagery alone. Title: Exploring Polarized Heliospheric Imaging Authors: Howard, T. A.; DeForest, C.; Tappin, S. J.; Odstrcil, D. Bibcode: 2013AGUSMSH42B..01H Altcode: Heliospheric imagers (first SMEI then the HIs) currently involve the imaging of unpolarized scattered light from free electrons in the solar wind plasma. Heliospheric imager datasets have a number of advantages over those of coronagraphs, primarily because of the broad nature of the Thomson scattering function that we call the "Thomson plateau". This means that the effects of scattering can be largely ignored over large angular extents, thereby reducing the problem of analysis to simply one of density and geometry. A further advantage that is exploited with coronagraphs but not yet with heliospheric imagers is with the use of polarimetry. Polarized images contain additional directional information and reduce numerous background noise sources, thereby enabling the extraction of additional information on coronal mass ejections and other solar wind transients. Using examples of polarized heliospheric images of a simulated CME, we explore how such information could be extracted from a future polarizing heliospheric imager for the utility of space weather forecasting. Title: Tracking Coronal Features from the Low Corona to Earth: A Quantitative Analysis of the 2008 December 12 Coronal Mass Ejection Authors: DeForest, C. E.; Howard, T. A.; McComas, D. J. Bibcode: 2013ApJ...769...43D Altcode: We have tracked a slow magnetic cloud associated coronal mass ejection (CME) continuously from its origin as a flux rope structure in the low solar corona over a four-day passage to impact with spacecraft located near Earth. Combining measurements from the STEREO, ACE, and Wind space missions, we are able to follow major elements with enough specificity to relate pre-CME coronal structure in the low corona to the corresponding elements seen in the near-Earth in situ data. Combining extreme ultraviolet imaging, quantitative Thomson scattering data throughout the flight of the CME, and "ground-truth" in situ measurements, we: (1) identify the plasma observed by ACE and Wind with specific features in the solar corona (a segment of a long flux rope); (2) determine the onset mechanism of the CME (destabilization of a filament channel following flare reconnection, coupled with the mass draining instability) and demonstrate that it is consistent with the in situ measurements; (3) identify the origin of different layers of the sheath material around the central magnetic cloud (closed field lifted from the base of the corona, closed field entrained during passage through the corona, and solar wind entrained by the front of the CME); (4) measure mass accretion of the system via snowplow effects in the solar wind as the CME crossed the solar system; and (5) quantify the kinetic energy budget of the system in interplanetary space, and determine that it is consistent with no long-term driving force on the CME. Title: Imaging the Variable Solar Wind Authors: DeForest, C.; Howard, T. A.; Matthaeus, W. H. Bibcode: 2013AGUSMSH31B..07D Altcode: With the advent of wide-field Thomson scattering imagery from STEREO/SECCHI, it is possible to image the solar wind continuously from its origin in the low corona to large fractions of 1AU from the Sun. Although it is sensitive only to non-stationary density structures, Thomson imaging yields morphological insight and global perspective that are not directly available from in-situ data. I will review recent work on both large and small scale analysis. On large scales, it is now possible to track well-presented CMEs from the pre-eruptive structure to impact with in-situ probes, yielding positive identification of flux rope structure based on both positively tracked morphology and direct magnetic measurement. In some cases, plasma detected in-situ can be positively identified with particular pieces of pre-eruptive anatomy in the low corona. Some observed large-scale features are as-yet unexplained. In quiet solar wind, small ejecta and blobs are readily distinguished from disconnection events that may be identified by their morphology, and all can be tracked through the Alfvén surface boundary at 20-50 Rs into the solar wind proper. In the HI-1 field of view, the solar wind takes on a flocculated appearance, though most of the individual features lose image structure and cannot be tracked across the entire field of view. Analysis of individual ejecta and of the statistical properties of the flocculation pattern is yielding insights into the nature of fluctuations and origin of variability in the slow solar wind. Title: Plasma Characteristic Determination During the Coronal Mass Ejection Associated with the January 27, 2012 Solar Storm Authors: Frahm, Rudy A.; Howard, Timothy; DeForest, Craig; Odstrcil, Dusan; Kallio, Esa; Mckenna-Lawler, Susan; Barabash, Stas; Winningham, J. David; Sharber, James R.; Elliott, Heather A. Bibcode: 2013EGUGA..1514062F Altcode: On January 27, 2012, an X-class flare was launched from the Sun at 18:15 UT. The X-class flare generated a high-energy particle stream flowing along the Interplanetary Magnetic Field (IMF) which arrived at Mars in about 39 minutes, with the resulting Coronal Mass Ejection (CME) arriving at Mars several days later. The Electron Spectrometer (ELS), part of the Analyzer of Space Plasmas and Energetic Atoms (ASPERA-3) experiment on the European Mars Express (MEx) Spacecraft, is used to show that the effect of the CME plasma caused an increase in the intensity of the energy flux within the Martian magnetosheath. Models of this event predicted the speed of the CME, which is used to identify which increase of the magnetosheath signature is due to the CME relating to this flare as several increases in Martian magnetosheath plasma are observed during the flare period. The Mars reaction, being an induced magnetosphere, responds to changes in solar wind conditions by continually self adjusting its magnetosheath to stand off the solar wind. Since the ion component of the solar wind interaction carries momentum away from the Sun, it is the electrons which must self adjust in order to maintain charge neutrality within the plasma and the proper induced current flow in order to stand-off changes in the solar wind. Here we examine the electron plasma properties during the forward CME shock in the Martian magnetosheath and describe the plasma conditions. Title: Point-spread Functions for the Extreme-ultraviolet Channels of SDO/AIA Telescopes Authors: Poduval, B.; DeForest, C. E.; Schmelz, J. T.; Pathak, S. Bibcode: 2013ApJ...765..144P Altcode: We present the stray-light point-spread functions (PSFs) and their inverses we characterized for the Atmospheric Imaging Assembly (AIA) EUV telescopes on board the Solar Dynamics Observatory (SDO) spacecraft. The inverse kernels are approximate inverses under convolution. Convolving the original Level 1 images with them produces images with improved stray-light characteristics. We demonstrate the usefulness of these PSFs by applying them to two specific cases: photometry and differential emission measure (DEM) analysis. The PSFs consist of a narrow Gaussian core, a diffraction component, and a diffuse component represented by the sum of a Gaussian-truncated Lorentzian and a shoulder Gaussian. We determined the diffraction term using the measured geometry of the diffraction pattern identified in flare images and the theoretically computed intensities of the principal maxima of the first few diffraction orders. To determine the diffuse component, we fitted its parameterized model using iterative forward-modeling of the lunar interior in the SDO/AIA images from the 2011 March 4 lunar transit. We find that deconvolution significantly improves the contrast in dark features such as miniature coronal holes, though the effect was marginal in bright features. On a percentage-scattering basis, the PSFs for SDO/AIA are better by a factor of two than that of the EUV telescope on board the Transition Region And Coronal Explorer mission. A preliminary analysis suggests that deconvolution alone does not affect DEM analysis of small coronal loop segments with suitable background subtraction. We include the derived PSFs and their inverses as supplementary digital materials. Title: The Thomson Surface. II. Polarization Authors: DeForest, C. E.; Howard, T. A.; Tappin, S. J. Bibcode: 2013ApJ...765...44D Altcode: 2012arXiv1207.5894D The solar corona and heliosphere are visible via sunlight that is Thomson-scattered off free electrons, yielding a radiance against the celestial sphere. In this second part of a three-article series, we discuss linear polarization of this scattered light parallel and perpendicular to the plane of scatter in the context of heliospheric imaging far from the Sun. The difference between these two radiances (pB) varies quite differently with scattering angle, compared to the sum that would be detected in unpolarized light (B). The difference between these two quantities has long been used in a coronagraphic context for background subtraction and to extract some three-dimensional information about the corona; we explore how these effects differ in the wider-field heliospheric imaging case where small-angle approximations do not apply. We develop an appropriately simplified theory of polarized Thomson scattering in the heliosphere, discuss signal-to-noise considerations, invert the scattering equations analytically to solve the three-dimensional object location problem for small objects, discuss exploiting polarization for background subtraction, and generate simple forward models of several classes of heliospheric feature. We conclude that pB measurements of heliospheric material are much more localized to the Thomson surface than are B measurements, that the ratio pB/B can be used to track solar wind features in three dimensions for scientific and space weather applications better in the heliosphere than corona, and that,as an independent measurement of background signal, pB measurements may be used to reduce the effect of background radiances including the stably polarized zodiacal light. Title: The Thomson Surface. III. Tracking Features in 3D Authors: Howard, T. A.; Tappin, S. J.; Odstrcil, D.; DeForest, C. E. Bibcode: 2013ApJ...765...45H Altcode: In this, the final installment in a three-part series on the Thomson surface, we present simulated observations of coronal mass ejections (CMEs) observed by a hypothetical polarizing white light heliospheric imager. Thomson scattering yields a polarization signal that can be exploited to locate observed features in three dimensions relative to the Thomson surface. We consider how the appearance of the CME changes with the direction of trajectory, using simulations of a simple geometrical shape and also of a more realistic CME generated using the ENLIL model. We compare the appearance in both unpolarized B and polarized pB light, and show that there is a quantifiable difference in the measured brightness of a CME between unpolarized and polarized observations. We demonstrate a technique for using this difference to extract the three-dimensional (3D) trajectory of large objects such as CMEs. We conclude with a discussion on how a polarizing heliospheric imager could be used to extract 3D trajectory information about CMEs or other observed features. Title: Energy release in the solar corona from spatially resolved magnetic braids Authors: Cirtain, J. W.; Golub, L.; Winebarger, A. R.; de Pontieu, B.; Kobayashi, K.; Moore, R. L.; Walsh, R. W.; Korreck, K. E.; Weber, M.; McCauley, P.; Title, A.; Kuzin, S.; Deforest, C. E. Bibcode: 2013Natur.493..501C Altcode: It is now apparent that there are at least two heating mechanisms in the Sun's outer atmosphere, or corona. Wave heating may be the prevalent mechanism in quiet solar periods and may contribute to heating the corona to 1,500,000 K (refs 1, 2, 3). The active corona needs additional heating to reach 2,000,000-4,000,000 K this heat has been theoretically proposed to come from the reconnection and unravelling of magnetic `braids'. Evidence favouring that process has been inferred, but has not been generally accepted because observations are sparse and, in general, the braided magnetic strands that are thought to have an angular width of about 0.2 arc seconds have not been resolved. Fine-scale braiding has been seen in the chromosphere but not, until now, in the corona. Here we report observations, at a resolution of 0.2 arc seconds, of magnetic braids in a coronal active region that are reconnecting, relaxing and dissipating sufficient energy to heat the structures to about 4,000,000 K. Although our 5-minute observations cannot unambiguously identify the field reconnection and subsequent relaxation as the dominant heating mechanism throughout active regions, the energy available from the observed field relaxation in our example is ample for the observed heating. Title: Imaging the origins of solar wind variability Authors: DeForest, C.; Howard, T. A. Bibcode: 2012AGUFMSH52A..08D Altcode: STEREO/SECCHI permits near-continuous imaging of of solar plasma packets as they form and propagate from the low, middle, and high corona into the heliosphere. The plasma packets in the solar wind "should" be visible as they leave the Sun. So why are they hard to view? Partly because it is difficult to identify the relevant phenomena against the changing, bright background of the corona itself. We will show recently produced movies from the COR and HI instruments in the STEREO/SECCHI suite, using new motion-filtering and background subtraction techniques that highlight variable features over the fixed and slowly-evolving streamer belt. These data reveal several potential sources of the solar wind variability, including packets of departing coronal material, signs of turbulent instabilities that may break up some streamers, and possible turbulent mixing in the low heliosphere. We will present initial results and discuss the course of future work. Title: Loop Evolution Observed with AIA and Hi-C Authors: Mulu-Moore, F.; Winebarger, A. R.; Cirtain, J. W.; Kobayashi, K.; Korreck, K. E.; Golub, L.; Kuzin, S.; Walsh, R. W.; DeForest, C.; De Pontieu, B.; Title, A. M.; Weber, M. Bibcode: 2012AGUFMSH33A2225M Altcode: In the past decade, the evolution of EUV loops has been used to infer the loop substructure. With the recent launch of High Resolution Coronal Imager (Hi-C), this inference can be validated. In this presentation we discuss the first results of loop analysis comparing AIA and Hi-C data. Title: The Fundamental Structure of Coronal Loops Authors: Winebarger, A. R.; Warren, H. P.; Cirtain, J. W.; Kobayashi, K.; Korreck, K. E.; Golub, L.; Kuzin, S.; Walsh, R. W.; DeForest, C.; De Pontieu, B.; Title, A. M.; Weber, M. Bibcode: 2012AGUFMSH31B..06W Altcode: During the past ten years, solar physicists have attempted to infer the coronal heating mechanism by comparing observations of coronal loops with hydrodynamic model predictions. These comparisons often used the addition of sub-resolution strands to explain the observed loop properties. On July 11, 2012, the High Resolution Coronal Imager (Hi-C) was launched on a sounding rocket. This instrument obtained images of the solar corona was 0.2-0.3'' resolution in a narrowband EUV filter centered around 193 Angstroms. In this talk, we will compare these high resolution images to simultaneous density measurements obtained with the Extreme Ultraviolet Imaging Spectrograph (EIS) on Hinode to determine whether the structures observed with Hi-C are resolved. Title: Observations of solar eruptions in the heliosphere Authors: DeForest, C.; Howard, T. A. Bibcode: 2012AGUFMSH54A..01D Altcode: The STEREO/SECCHI instrument suite now permits quantitative imaging of heliospheric plasmas. This capability realizes the vision of SECCHI: complete, quantitative Sun-to-Earth tracking of eruptive events large and small. Current analyses show that all currently analyzed CMEs preserve coronal flux structures intact from Sun to Earth, albeit with distortions that appear inconsistent with symmetric "magnetic cloud" models; that visible, impulsive flux disconnection events may set the equilibrium value of the interplanetary magnetic field; that ongoing force driving results in mass accretion rather than event acceleration; and that, while some slow solar wind packets appear to erupt from the corona, others may form in flight. We will present these new results and report a new project to post-process and make available the entire SECCHI-A heliospheric data set. Title: Evolution of Coronal Bright Points and Photospheric Magnetic Fields Authors: Lamb, D. A.; Saar, S.; DeForest, C. Bibcode: 2012AGUFMSH33A2227L Altcode: Coronal bright points are excellent probes of the connection between the photosphere and corona, and occur in sufficiently larger numbers all over the Sun to make statistical or ensemble studies necessary and useful. We present initial results on the evolution of coronal bright points and the state of the associated photospheric magnetic field. Using an automated bright point detection algorithm that has found thousands of bright points in multiple SDO/AIA passbands, combined with an automated magnetic feature tracking algorithm on SDO/HMI magnetograms, we explore the magnetic conditions necessary for bright point formation and destruction. Title: Revelations on Heliospheric Imaging of Polarized Light Authors: Howard, T. A.; DeForest, C.; Tappin, J.; Odstrcil, D. Bibcode: 2012AGUFMSH41B2103H Altcode: We report on recent developments on the theory of observing the inner heliosphere with heliospheric imagers. We have extended the theory of Thomson scattering, which governs the appearance of features observed by heliospheric imagers, to polarized light observations, and consider potential benefits to the analysis of features observed with a polarizing heliospheric imager. We find that when observing in unpolarized light (as do the current generation of heliospheric imagers), it is difficult to identify the 3-D location of observed features because of the broad nature of the scattering function (causing the Thomson surface to be a Thomson plateau). The broadening does not occur in polarized light observations, enabling the accurate 3-D location of features to be determined. Our theory is validated by recent unpolarized light observations from the STEREO/HI-2 heliospheric imager, and with polarized light simulations of coronal mass ejection simulations using the ENLIL model. Title: White-light Observations of Solar Wind Transients and Comparison with Auxiliary Data Sets Authors: Howard, T. A.; DeForest, C. E.; Reinard, A. A. Bibcode: 2012ApJ...754..102H Altcode: This paper presents results utilizing a new data processing pipeline for STEREO/SECCHI. The pipeline is used to identify and track 24 large- and small-scale solar wind transients from the Sun out to 1 AU. This comparison was performed during a few weeks around the minimum at the end of Solar Cycle 23 and the start of Cycle 24 (2008 December to 2009 January). We use coronagraph data to identify features near the Sun, track them through HI-2A, and identify their signatures with in situ data at the Earth and STEREO-B. We provide measurements and preliminary analysis of the in situ signatures of these features near 1 AU. Along with the demonstration of the utility of heliospheric imagers for tracking even small-scale structures, we identify and discuss an important limitation in using geometric triangulation for determining three-dimensional properties. Title: The Thomson Surface. I. Reality and Myth Authors: Howard, T. A.; DeForest, C. E. Bibcode: 2012ApJ...752..130H Altcode: The solar corona and heliosphere are visible via sunlight that is Thomson-scattered off free electrons and detected by coronagraphs and heliospheric imagers. It is well known that these instruments are most responsive to material at the "Thomson surface," the sphere with a diameter passing through both the observer and the Sun. It is less well known that in fact the Thomson scattering efficiency is minimized on the Thomson surface. Unpolarized heliospheric imagers such as STEREO/HI are thus approximately equally responsive to material over more than a 90° range of solar exit angles at each given position in the image plane. We call this range of angles the "Thomson plateau." We observe that heliospheric imagers are actually more sensitive to material far from the Thomson surface than close to it, at a fixed radius from the Sun. We review the theory of Thomson scattering as applied to heliospheric imaging, feature detection in the presence of background noise, geometry inference, and feature mass measurement. We show that feature detection is primarily limited by observing geometry and field of view, that the highest sensitivity for detection of density features is to objects close to the observer, that electron surface density inference is independent of geometry across the Thomson plateau, and that mass inference varies with observer distance in all geometries. We demonstrate the sensitivity results with a few examples of features detected by STEREO, far from the Thomson surface. Title: Quantitative Imaging of the Solar Wind: CME Mass Evolution and the Interplanetary Magnetic Flux Balance Authors: DeForest, Craig Bibcode: 2012AAS...22051504D Altcode: We recently developed post-processing techniques for heliospheric images from the STEREO spacecraft; the new data sets enable, for the first time, quantitative photometric studies of evolving wind features at distances up to 1 A.U. from the Sun. We have used the new data to trace several CMEs and magnetic disconnection events to their origins in the solar corona, and to infer the force balance and entrained magnetic flux in those features. We present recent results showing the relationship between ICME and CME anatomy, in particular the origin of an observed interplanetary flux rope and the relationship between original launched solar material and piled-up sheath material and flux in the storm at 1. A.U. We discuss implications for understanding space weather physics and predicting individual events, and point out the importance of future imaging technologies such as polarized heliospheric imaging. Title: Fix Up Your AIA Images: A Complete Empirically Determined Set of PSFs And Their Inverses for the AIA EUV Channels Authors: DeForest, Craig; Poduval, B.; Schmelz, J. Bibcode: 2012AAS...22020704D Altcode: All EUV imagers to date have had significant stray "light" in the instrument point-spread function, taking the form of very broad, low-level wings that disperse low, hard-to-measure amounts of radiance into pixels far from the core of the PSF -- but whose integrated intensity is a significant fraction of total received energy. This results in a hazy appearance to EUV images of the Sun. Thus, to obtain quantitative results from any EUV imager it is necessary to characterize the PSF via forward modeling of a distributed object rather than only (as is done on the ground) with a bright point source.

We have prepared and tested empirical PSF functions for each of the six EUV channels in the SDO/AIA instrument, and present them here. We have also prepared inverse PSFs that can be used for simple deconvolution of stray light from Level 1 AIA data: simply convolve the subject data with the inverse PSF to improve its stray light characteristics.

We present our results and some sample images, together with the imaging improvements afforded by known-PSF deconvolution. The bottom line: AIA performs notably better than past instruments but still requires care when interpreting "diffuse" brightness in the images. We will demonstrate how deconvolution affects a particular photometric application: DEM determination of different coronal features. Title: SWAMIS Magnetic Feature Tracking for SDO Authors: DeForest, Craig; Lamb, D.; Davey, A.; Timmons, R. Bibcode: 2012AAS...22020705D Altcode: Flux emergence is central to a host of problems in solar dynamics, from the birth of new active regions and the space weather effects that result, to the maintenance of quiet sun magnetism at all phases of the solar cycle. The Southwest Automatic Magnetic Identification Suite emerging magnetic flux region detection module (SWAMIS-EF) is running on near-real-time magnetograms from the Helioseismic and Magnetic Imager on the Solar Dynamics Observatory. This enables near-real-time automated detection and cataloging of emerging flux regions from the active region scale down to the scale of the supergranular magnetic network. We will present an overview of the emerging flux detection algorithm, show some detailed observations of emerging flux at a variety of spatial scales, and describe some of the emerging flux region summary quantities that are output to the Heliophysics Event Knowledgebase. Finally, we will describe current progress in developing Scientific SWAMIS, an adaptation and optimization of the SWAMIS tracking algorithm to run on full disk, full resolution HMI line-of-sight magnetograms. Title: PSF Correction for AIA Using Lunar Limb Data Authors: DeForest, Craig; Poduval, Bala Bibcode: 2012decs.confE.121D Altcode: PSF correction is important for myriad inferences that can be made from EUV imagery, including heating distribution and impulsivity; DEM; and wave amplitude measurements. Using lunar limb and solar flare data, we have prepared model PSF functions to describe the scattering performance of the six EUV channels of AIA. We have not attempted to model the core of the PSF (focus), only its wings (stray light) of each channel. We find that, typically, about half of the scattered light is in the diffuse component of the PSF model, although there is significant variation across the channels. The diffraction component of the PSF was determined by direct inspection of the diffraction pattern from flaring images, with some a priori knowledge of the physics and nature of the diffraction grid (following the methods of Gburek on TRACE and more recently, Cheung on AIA); and the diffuse component was determined by iteratively fitting imaging performance around the lunar limb in eclipse images, with the assumption that the Moon is dark in the EUV. We present the PSFs and summary data, along with a preliminary comparision with the diffraction-only models developed at SAO, and describe where to get both the quantitative PSF models and their inverses (for direct deconvolution) in FITS format. Title: Inner Heliospheric Flux Rope Evolution via Imaging of Coronal Mass Ejections Authors: Howard, T. A.; DeForest, C. E. Bibcode: 2012ApJ...746...64H Altcode: Understanding the evolution of flux ropes in coronal mass ejections (CMEs) is of importance both to the scientific and technological communities. Scientifically their presence is critical to models describing CME launch and they likely play a role in CME evolution. Technologically they are the major contributor to severe geomagnetic storms. Using a new processing technique on the STEREO/SECCHI heliospheric imaging data, we have tracked a magnetic flux rope observed by the Wind spacecraft in December 2008 to its origins observed by coronagraphs. We thereby establish that the cavity in the classic three-part coronagraph CME is the feature that becomes the magnetic cloud. This implies that the bright material ahead of the cavity is piled-up coronal or solar wind material. We track the evolution of the cavity en-route and find that its structure transforms from concave inward (curving away from the Sun) to concave outward (toward the Sun) around 0.065 AU from the Sun. The pileup was tracked and its leading edge remained concave inward throughout its journey. Two other CMEs in January 2009 are also inspected and a similar cavity is observed in each, suggesting that they too each contained a flux rope. The results presented here are the first direct observation, through continuous tracking, associating a particular flux rope observed in situ with the same flux rope before ejection from the corona. We speculate that detailed heliospheric imagery of CMEs may lead to a means by which flux ropes can be identified remotely in the heliosphere. Title: Computer Vision for the Solar Dynamics Observatory (SDO) Authors: Martens, P. C. H.; Attrill, G. D. R.; Davey, A. R.; Engell, A.; Farid, S.; Grigis, P. C.; Kasper, J.; Korreck, K.; Saar, S. H.; Savcheva, A.; Su, Y.; Testa, P.; Wills-Davey, M.; Bernasconi, P. N.; Raouafi, N. -E.; Delouille, V. A.; Hochedez, J. F.; Cirtain, J. W.; DeForest, C. E.; Angryk, R. A.; De Moortel, I.; Wiegelmann, T.; Georgoulis, M. K.; McAteer, R. T. J.; Timmons, R. P. Bibcode: 2012SoPh..275...79M Altcode: 2011SoPh..tmp..144M; 2011SoPh..tmp..213M; 2011SoPh..tmp....8M In Fall 2008 NASA selected a large international consortium to produce a comprehensive automated feature-recognition system for the Solar Dynamics Observatory (SDO). The SDO data that we consider are all of the Atmospheric Imaging Assembly (AIA) images plus surface magnetic-field images from the Helioseismic and Magnetic Imager (HMI). We produce robust, very efficient, professionally coded software modules that can keep up with the SDO data stream and detect, trace, and analyze numerous phenomena, including flares, sigmoids, filaments, coronal dimmings, polarity inversion lines, sunspots, X-ray bright points, active regions, coronal holes, EIT waves, coronal mass ejections (CMEs), coronal oscillations, and jets. We also track the emergence and evolution of magnetic elements down to the smallest detectable features and will provide at least four full-disk, nonlinear, force-free magnetic field extrapolations per day. The detection of CMEs and filaments is accomplished with Solar and Heliospheric Observatory (SOHO)/Large Angle and Spectrometric Coronagraph (LASCO) and ground-based Hα data, respectively. A completely new software element is a trainable feature-detection module based on a generalized image-classification algorithm. Such a trainable module can be used to find features that have not yet been discovered (as, for example, sigmoids were in the pre-Yohkoh era). Our codes will produce entries in the Heliophysics Events Knowledgebase (HEK) as well as produce complete catalogs for results that are too numerous for inclusion in the HEK, such as the X-ray bright-point metadata. This will permit users to locate data on individual events as well as carry out statistical studies on large numbers of events, using the interface provided by the Virtual Solar Observatory. The operations concept for our computer vision system is that the data will be analyzed in near real time as soon as they arrive at the SDO Joint Science Operations Center and have undergone basic processing. This will allow the system to produce timely space-weather alerts and to guide the selection and production of quicklook images and movies, in addition to its prime mission of enabling solar science. We briefly describe the complex and unique data-processing pipeline, consisting of the hardware and control software required to handle the SDO data stream and accommodate the computer-vision modules, which has been set up at the Lockheed-Martin Space Astrophysics Laboratory (LMSAL), with an identical copy at the Smithsonian Astrophysical Observatory (SAO). Title: Disconnecting Open Solar Magnetic Flux Authors: DeForest, C. E.; Howard, T. A.; McComas, D. J. Bibcode: 2012ApJ...745...36D Altcode: 2011arXiv1111.7211D Disconnection of open magnetic flux by reconnection is required to balance the injection of open flux by coronal mass ejections and other eruptive events. Making use of recent advances in heliospheric background subtraction, we have imaged many abrupt disconnection events. These events produce dense plasma clouds whose distinctive shape can now be traced from the corona across the inner solar system via heliospheric imaging. The morphology of each initial event is characteristic of magnetic reconnection across a current sheet, and the newly disconnected flux takes the form of a "U-"shaped loop that moves outward, accreting coronal and solar wind material. We analyzed one such event on 2008 December 18 as it formed and accelerated at 20 m s-2 to 320 km s-1, thereafter expanding self-similarly until it exited our field of view 1.2 AU from the Sun. From acceleration and photometric mass estimates we derive the coronal magnetic field strength to be 8 μT, 6 R ⊙ above the photosphere, and the entrained flux to be 1.6 × 1011 Wb (1.6 × 1019 Mx). We model the feature's propagation by balancing inferred magnetic tension force against accretion drag. This model is consistent with the feature's behavior and accepted solar wind parameters. By counting events over a 36 day window, we estimate a global event rate of 1 day-1 and a global solar minimum unsigned flux disconnection rate of 6 × 1013 Wb yr-1 (6 × 1021 Mx yr-1) by this mechanism. That rate corresponds to ~ - 0.2 nT yr-1 change in the radial heliospheric field at 1 AU, indicating that the mechanism is important to the heliospheric flux balance. Title: Flux Ropes and Small-Scale Interplanetary Transients - New Revelations from STEREO/SECCHI Authors: Howard, T. A.; DeForest, C. E.; Reinard, A. A.; Tappin, S. J. Bibcode: 2011AGUFMSH23C1966H Altcode: We present scientific results using a new processing pipeline from the SECCHI instrument suite on STEREO-A. This pipeline reduces stellar and F coronal noise to an unprecedented level to where very small and faint solar wind transients can be observed and tracked. This allows the accomplishment of new revelations about small-scale transients and about the anatomy of coronal mass ejections (CMEs) en-route through the inner heliosphere. Our results are from the time period corresponding to the lowest part of the deep minimum of Solar Cycle 23-24 (December 2009 - January 2009) and find a dynamic solar wind even when at its quietest. We identify solar wind puffs and blobs, likely disconnection events, and a number of CMEs, and we track them through the SECCHI suite to distances out to and beyond 1 AU. We are therefore able to unambiguously identify each of their signatures upon their arrival at in-situ spacecraft. For the CMEs we track magnetic flux ropes (called magnetic clouds) back to their coronagraph origins and identify them as the cavity component of the so-called classic three-part CME structure. Finally we track the evolution of the structure of the flux ropes through the heliosphere, and find significant distortion. Title: Investigations to Determine the Origin of the Solar Wind with the SPICE EUV Imaging Spectrograph and the Solar Orbiter Mission Authors: Hassler, D. M.; Deforest, C.; Spice Team Bibcode: 2011AGUFMSH33B2054H Altcode: At large spatial scales, the structure of the solar wind and it's mapping back to the solar corona, is thought to be reasonably well understood. However, the detailed structure of the various source regions at chromospheric and transition region heights is extremely complex, and less well understood. Determining this connection between heliospheric structures and their source regions at the Sun is one of the overarching objective of the Solar Orbiter mission. During perihelion segments of its orbit, when the spacecraft is in quasi-corotation with the Sun, Solar Orbiter will determine the plasma parameters and compositional signatures of the solar wind, which can be compared directly with the spectroscopic signatures of coronal ions with differing charge-to-mass ratios and FIP. One of the key instruments on the Solar Orbiter mission to make these remote sensing measurements is the SPICE (Spectral Imaging of the Coronal Environment) imaging spectrograph. SPICE will provide the images and plasma diagnostics needed to characterize the plasma state in different source regions, from active regions to quiet Sun to coronal holes. By comparing composition, plasma parameters, and low/high FIP ratios of structures remotely, with those measured directly at the Solar Orbiter spacecraft, Solar Orbiter will provide the first direct link between solar wind structures and their source regions at the Sun. This talk will provide a background of previous compositional correlation measurements and an outline of the method to be used for comparing the spectroscopic and in-situ plasma parameters to be measured with Solar Orbiter. Title: Imaging the Turbulent Solar Wind with STEREO/SECCHI Authors: DeForest, C.; Howard, T. A.; Matthaeus, W. H. Bibcode: 2011AGUFMSH44B..02D Altcode: Newly processed data from STEREO/SECCHI offer a glimpse into the development of turbulence in the heliospheric current sheet and the slow solar wind. Careful background subtraction yields photometrically calibrated images of "moving feature excess density" throughout the inner heliosphere near the plane of the ecliptic. We report on initial work extracting the structure function of dense features via remote sensing of the Thomson scattered sunlight from free electron clouds in the inner heliosphere. Precise imaging results of this type show promise in enabling extraction of quantitative information about interplanetary turbulence from direct imaging. Title: Observations of Emerging Flux Regions with SWAMIS-EF Authors: Lamb, Derek A.; DeForest, Craig E.; Davey, Alisdair R.; Timmons, Ryan P. Bibcode: 2011sdmi.confE..59L Altcode: The SWAMIS magnetic feature tracking algorithm is working in the SDO pipeline to detect emerging flux regions from the size of active regions down to ephemeral regions. We will present a brief overview of the emerging flux detection algorithm, show a sample of events as one would see them in the HEK, and show some examples illustrating the underlying performance of the algorithm in more detail than is available in the HEK. Finally, we will present some measurements of the amount of magnetic flux emergence detected by the algorithm over a month-long time period and compare that with previously-published estimates of the magnetic flux emergence rate. SWAMIS-EF enables such previously-difficult measurements to now be routinely made. Title: Observations of Detailed Structure in the Solar Wind at 1 AU with STEREO/HI-2 Authors: DeForest, C. E.; Howard, T. A.; Tappin, S. J. Bibcode: 2011ApJ...738..103D Altcode: 2011arXiv1104.1615D We present images of solar wind electron density structures at distances of 1 AU, extracted from the STEREO/HI-2 data. Collecting the images requires separating the Thomson-scattered signal from the other background/foreground sources that are 103 times brighter. Using a combination of techniques, we are able to generate calibrated imaging data of the solar wind with sensitivity of a few × 10-17 B sun, compared to the background signal of a few × 10-13 B sun, using only the STEREO/HI-2 Level 1 data as input. These images reveal detailed spatial structure in coronal mass ejections (CMEs) and the solar wind at projected solar distances in excess of 1 AU, at the instrumental motion-blur resolution limit of 1°-3°. CME features visible in the newly reprocessed data from 2008 December include leading-edge pileup, interior voids, filamentary structure, and rear cusps. "Quiet" solar wind features include V-shaped structures centered on the heliospheric current sheet, plasmoids, and "puffs" that correspond to the density fluctuations observed in situ. We compare many of these structures with in situ features detected near 1 AU. The reprocessed data demonstrate that it is possible to perform detailed structural analyses of heliospheric features with visible light imagery, at distances from the Sun of at least 1 AU. Title: Fluxon Simulations of Magnetic Reconnection at Coronal Hole Boundaries Authors: Lamb, Derek Allen; DeForest, Craig E. Bibcode: 2011shin.confE.172L Altcode: Because the equatorial extensions of polar coronal holes rotate more rigidly than the underlying photosphere, they have long been assumed to have substantial magnetic reconnection at their boundaries. However, evidence for this reconnection has been sparse until very recently. We assume that reconnection facilitated by the evolving small-scale magnetic fields can drive at least some of the coronal hole boundary evolution. We hypothesize that a bias in the direction of that reconnection, perhaps imposed by the faster rotation of the upper corona, is sufficient to give equatorial coronal holes their rigid rotation. We present some preliminary simulations using FLUX, a reconnection-controlled coronal MHD simulation framework, of the reconnection at coronal hole - quiet sun boundaries. Title: Small-Scale Magnetic Reconnection at Equatorial Coronal Hole Boundaries Authors: Lamb, Derek; DeForest, C. E. Bibcode: 2011SPD....42.1832L Altcode: 2011BAAS..43S.1832L Coronal holes have long been known to be the source of the fast solar wind at both high and low latitudes. The equatorial extensions of polar coronal holes have long been assumed to have substantial magnetic reconnection at their boundaries, because they rotate more rigidly than the underlying photosphere. However, evidence for this reconnection has been sparse until very recently. We present some evidence that reconnection due to the evolution of small-scale magnetic fields may be sufficient to drive coronal hole boundary evolution. We hypothesize that a bias in the direction of that reconnection is sufficient to give equatorial coronal holes their rigid rotation. We discuss the prospects for investigating this using FLUX, a reconnection-controlled coronal MHD simulation framework. This work was funded by the NASA SHP-GI program. Title: Imaging The Solar Wind At 1 AU. With Stereo/hi-2 Authors: DeForest, Craig; Howard, T.; Tappin, J. Bibcode: 2011SPD....42.1402D Altcode: 2011BAAS..43S.1402D The STEREO/HI-2 wide-field imagers have demonstrated the importance of heliospheric imaging to understanding CMEs and the solar wind, but the difficulty of background subtraction has precluded full exploitation of this rich resource: current results are based mainly on morphological studies of running difference movies and time-elongation "J-plots". With a combination of several commonly used image processing techniques, we have developed a pipeline to extract quantitative wind imagery from HI-2 at elongation angles as high as 70 degrees from the Sun and brightness ranges 3-4 orders of magnitude fainter than the background.

The processed data reveal to direct view a surprising menagerie of features in the solar wind: voids within CMEs, remnant loop structures, disconnected plasmoids, current sheets, interacting streams, and compressive wave fronts. Despite motion blur of 1-3 degrees in the HI-2 instrument, in some cases the images are clear enough to reveal striated "tracer” structures that appear to follow the magnetic field, just as in the solar corona. We will briefly summarize the reduction pipeline, demonstrate its output with spectacular movies of Earth-directed events and "quiet Sun", and present preliminary results from examination of the quantitative data. This work was supported in major part by NASA's SHP-GI program. Title: Investigations to Determine the Origin of the Solar Wind with SPICE and SolarOrbiter Authors: Hassler, Donald M.; DeForest, C.; Wilkinson, E.; Davila, J.; SPICE Team Bibcode: 2011SPD....42.2402H Altcode: 2011BAAS..43S.2402H At large spatial scales, the structure of the solar wind and it's mapping back to the solar corona, is thought to be reasonably well understood. However, the detailed structure of the various source regions at chromospheric and transition region heights is extremely complex, and less well understood. Determining this connection between heliospheric structures and their source regions at the Sun is one of the overarching objective of the Solar Orbiter mission.

During perihelion segments of its orbit, when the spacecraft is in quasi-corotation with the Sun, Solar Orbiter will determine the plasma parameters and compositional signatures of the solar wind, which can be compared directly with the spectroscopic signatures of coronal ions with differing charge-to-mass ratios and FIP. One of the key instruments on the Solar Orbiter mission to make these remote sensing measurements is the SPICE (Spectral Imaging of the Coronal Environment) imaging spectrograph. SPICE will provide the images and plasma diagnostics needed to characterize the plasma state in different source regions, from active regions to quiet Sun to coronal holes. By comparing composition, plasma parameters, and low/high FIP ratios of structures remotely, with those measured directly at the Solar Orbiter spacecraft, Solar Orbiter will provide the first direct link between solar wind structures and their source regions at the Sun.

This talk will provide a background of previous compositional correlation measurements and an outline of the method to be used for comparing the spectroscopic and in-situ plasma parameters to be measured with Solar Orbiter. Title: Solar Orbiter Core Science With the SPICE Spectral Imager Authors: DeForest, Craig; Hassler, D.; Wilkinson, E.; SPICE Science Team Bibcode: 2011SPD....42.1503D Altcode: 2011BAAS..43S.1503D SPICE is a novel spectral imager designed for deployment on Solar Orbiter, and directly addresses the core science using high level science data products including Dopplergrams, "FIPograms" and "QMograms" to correlate solar wind source regions at the surface of the Sun with in situ measurements made simultaneously on board Solar Orbiter.

SPICE data are critical to the key motivating questions for the Solar Orbiter mission, and the data products and observing plans draw heavily from lessons learned in the SOHO mission to yield accessible data products that can be compared easily with other types of solar data. We describe key questions that Solar Orbiter will address, and how SPICE data products enable answering them. Title: The Evolution Of Coronal Mass Ejections And Large Solar Wind Structures Authors: Howard, Tim A.; DeForest, C. E.; Reinard, A. A. Bibcode: 2011SPD....42.1308H Altcode: 2011BAAS..43S.1308H Processing of STEREO/HI-2 heliospheric image data has reached a level where extremely faint structures can be tracked through their entire trajectory to 1 AU. This enables detailed comparison with auxiliary datasets allowing an unambiguous identification of solar wind transient structures from the Sun to 1 AU and beyond. These transients are in the scale range from large CMEs to "puffs" only a few hundred Mm across. For events that impact in-situ spacecraft, we are able to make quantitative measurements of these transients without the confusion involving the identification of heliospheric image features. We present results utilizing a new processing pipeline of HI-2 data developed by DeForest et al. (2011) that link transient features observed by white light coronagraphs with in-situ datasets near 1 AU. The results include attempts of three-dimensional reconstruction, trajectory and kinematic evolution of these features, along with a detailed in-situ analysis of the magnetic field and plasma comprising each of the features. Title: Preliminary PSF Inversion for SDO/AIA Lunar Occutation Data Authors: DeForest, Craig; Poduval, B. Bibcode: 2011SPD....42.2127D Altcode: 2011BAAS..43S.2127D We present initial results from PSF inversion of the AIA eclipse data from fall 2010. Initial stray light estimates for the 171 band are favorable compared to TRACE, and comparable to STEREO/EUVI. Title: A Microsatellite Heliospheric Imaging Network for Science and Space Weather Authors: Deforest, C. E.; Howard, T. A.; Kief, C.; Chime Mission Development Team Bibcode: 2010AGUFMSH41A1779D Altcode: Heliospheric imaging has been shown to yield new insight into ICME physics, and to improve greatly space weather prediction at Earth. However, all existing heliospheric imagers are either well past prime mission (SMEI) or soon to be unable to view near-Earth space (STEREO/HI). We present a novel approach to heliospheric imaging, using a constellation of microsatellites in Sun-synchronous LEO. Recent developments in component miniaturization and standardization allow very inexpensive, very small spacecraft, dominated by an optical baffle in the 30cm size range, to image propagating features in the solar wind. Such spacecraft can be produced and deployed as a constellation to improve imaging cadence and reveal new physics of Earthbound CMEs and other solar wind features. Further, using a constellation improves reliability into the operational class (mean time between failures well over 100 years for the network as a whole), for a fraction of the cost of a single traditional operational-class instrument that can monitor ICMEs to predict space weather. Other advantages conferred by using low-cost LEO microsatellites outweigh challenges of designing to the small form factor. Sensitivity analysis shows that such a microsatellite constellation will enable new scientific measurements relevant to ICME evolution, shock formation, and solar wind propagation that are inaccessible from existing heliospheric imagers and conventional instrument designs, answering fundamental questions about how solar effects interact with the heliosphere. Title: Finding Magnetic Features and Emerging Flux Regions in HMI Data with SWAMIS Authors: Lamb, D. A.; Deforest, C. Bibcode: 2010AGUFMSH22A..06L Altcode: We present an adaptation of the Southwest Automatic Magnetic Identification Suite (SWAMIS) feature tracking algorithm for use in the SDO-HMI pipeline. Feature tracking algorithms have been used by several groups to identify features in what are now relatively small magnetogram datasets. They have been used across a large range of scales, from active regions to the smallest features visible with Hinode SOT. SWAMIS is being incorporated into the SDO-HMI pipeline in two forms: to identify large flux emergence regions, and to track every feature seen by HMI. This will enable real-time detection of events of interest to space weather forecasters, as well as large statistical studies of HMI data. We will describe the status of this code in the HMI pipeline and provide some examples of its use. A stand-alone version of the software for use on fixed-size datasets is also available. Title: Solar Magnetic Tracking. III. Apparent Unipolar Flux Emergence in High-resolution Observations Authors: Lamb, D. A.; DeForest, C. E.; Hagenaar, H. J.; Parnell, C. E.; Welsch, B. T. Bibcode: 2010ApJ...720.1405L Altcode: Understanding the behavior of weak magnetic fields near the detection limit of current instrumentation is important for determining the flux budget of the solar photosphere at small spatial scales. Using 0farcs3-resolution magnetograms from the Solar Optical Telescope's Narrowband Filter Imager (NFI) on the Hinode spacecraft, we confirm that the previously reported apparent unipolar magnetic flux emergence seen in intermediate-resolution magnetograms is indeed the coalescence of previously existing flux. We demonstrate that similar but smaller events seen in NFI magnetograms are also likely to correspond to the coalescence of previously existing weak fields. The uncoalesced flux, detectable only in the ensemble average of hundreds of these events, accounts for 50% of the total flux within 3 Mm of the detected features. The spatial scale at which apparent unipolar emergence can be directly observed as coalescence remains unknown. The polarity of the coalescing flux is more balanced than would be expected given the imbalance of the data set, however without further study we cannot speculate whether this implies that the flux in the apparent unipolar emergence events is produced by a granulation-scale dynamo or is recycled from existing field. Title: Symmetric Coronal Jets: A Reconnection-controlled Study Authors: Rachmeler, L. A.; Pariat, E.; DeForest, C. E.; Antiochos, S.; Török, T. Bibcode: 2010ApJ...715.1556R Altcode: Current models and observations imply that reconnection is a key mechanism for destabilization and initiation of coronal jets. We evolve a system described by the theoretical symmetric jet formation model using two different numerical codes with the goal of studying the role of reconnection in this system. One of the codes is the Eulerian adaptive mesh code ARMS, which simulates magnetic reconnection through numerical diffusion. The quasi-Lagrangian FLUX code, on the other hand, is ideal and able to evolve the system without reconnection. The ideal nature of FLUX allows us to provide a control case of evolution without reconnection. We find that during the initial symmetric and ideal phase of evolution, both codes produce very similar morphologies and energy growth. The symmetry is then broken by a kink-like motion of the axis of rotation, after which the two systems diverge. In ARMS, current sheets formed and reconnection rapidly released the stored magnetic energy. In FLUX, the closed field remained approximately constant in height while expanding in width and did not release any magnetic energy. We find that the symmetry threshold is an ideal property of the system, but the lack of energy release implies that the observed kink is not an instability. Because of the confined nature of the FLUX system, we conclude that reconnection is indeed necessary for jet formation in symmetric jet models in a uniform coronal background field. Title: Hinode Solar Optical Telescope Observations of the Source Regions and Evolution of "Type II" Spicules at the Solar Polar Limb Authors: Sterling, Alphonse C.; Moore, Ronald L.; DeForest, Craig E. Bibcode: 2010ApJ...714L...1S Altcode: We examine solar spicules using high-cadence Ca II data of the north pole coronal hole region, using the Solar Optical Telescope (SOT) on the Hinode spacecraft. The features we observe are referred to as "Type II" spicules by De Pontieu et al. in 2007. By convolving the images with the inverse-point-spread function for the SOT Ca II filter, we are able to investigate the roots of some spicules on the solar disk, and the evolution of some spicules after they are ejected from the solar surface. We find that the source regions of at least some of the spicules correspond to locations of apparent-fast-moving (~few × 10 km s-1), transient (few 100 s), Ca II brightenings on the disk. Frequently the spicules occur when these brightenings appear to collide and disappear. After ejection, when seen above the limb, many of the spicules fade by expanding laterally (i.e., roughly transverse to their motion away from the solar surface), splitting into two or more spicule "strands," and the spicules then fade without showing any downward motion. Photospheric/chromospheric acoustic shocks alone likely cannot explain the high velocities (~100 km s-1) of the spicules. If the Ca II brightenings represent magnetic elements, then reconnection among those elements may be a candidate to explain the spicules. Alternatively, many of the spicules could be small-scale magnetic eruptions, analogous to coronal mass ejections, and the apparent fast motions of the Ca II brightenings could be analogs of flare loops heated by magnetic reconnection in these eruptions. Title: Computer Vision for SDO: First Results from the SDO Feature Finding Algorithms Authors: Martens, Petrus C.; Attrill, G.; Davey, A.; Engell, A.; Farid, S.; Grigis, P.; Kasper, J.; Korreck, K.; Saar, S.; Su, Y.; Testa, P.; Wills-Davey, M.; Bernasconi, P.; Raouafi, N.; Georgoulis, M.; Deforest, C.; Peterson, J.; Berghoff, T.; Delouille, V.; Hochedez, J.; Mampaey, B.; Verbeek, C.; Cirtain, J.; Green, S.; Timmons, R.; Savcheva, A.; Angryk, R.; Wiegelmann, T.; McAteer, R. Bibcode: 2010AAS...21630804M Altcode: The SDO Feature Finding Team produces robust and very efficient software modules that can keep up with the relentless SDO data stream, and detect, trace, and analyze a large number of phenomena including: flares, sigmoids, filaments, coronal dimmings, polarity inversion lines, sunspots, X-ray bright points, active regions, coronal holes, EIT waves, CME's, coronal oscillations, and jets. In addition we track the emergence and evolution of magnetic elements down to the smallest features that are detectable, and we will also provide at least four full disk nonlinear force-free magnetic field extrapolations per day.

During SDO commissioning we will install in the near-real time data pipeline the modules that provide alerts for flares, coronal dimmings, and emerging flux, as well as those that trace filaments, sigmoids, polarity inversion lines, and active regions. We will demonstrate the performance of these modules and illustrate their use for science investigations. Title: Emerging Flux Detection for the Solar Dynamics Observatory Authors: DeForest, Craig; Peterson, J. Bibcode: 2010AAS...21640209D Altcode: 2010BAAS...41..874D We present an emerging-flux detection method and code that are being incorporated into the early warning pipeline for the Solar Dynamics Observatory. SWAMIS is a magnetic feature tracking code that has been used primarily to probe the small scale solar dynamo; we have adapted it to find large scale bipolar emergences of new flux in time series of HMI full-disk line of sight magnetograms. The new code, SWAMIS-EF, performs feature identification and tracking on multiple spatial scales to identify large flux emergence events that, at full instrument resolution, segment into large clusters of small feature motions. SWAMIS-EF generates flux-emergence event records that highlight all large scale flux emergences (>10 EMx of magnetic flux) in the favorable portion of the solar disk (nominally, within 0.86 Rs of disk center). A variant on the code, "SWAMIS-S", will describe the motion and interactions of every single resolvable magnetic feature on the Sun, and is anticipated by the end of Mission Year 1. The SWAMIS-EF event stream will enable both improved space weather prediction and retrospective "data mining" studies of the solar dynamo and the effect of flux emergence on the chromosphere and corona. Title: Solar Polar Spicules Observed with Hinode Authors: Sterling, Alphonse C.; Moore, R. L.; DeForest, C. E. Bibcode: 2010AAS...21640303S Altcode: 2010BAAS...41Q.878S We examine solar polar region spicules using high-cadence Ca II data from the Solar Optical Telescope (SOT) on the Hinode spacecraft. We sharpened the images by convolving them with the inverse-point-spread function of the SOT Ca II filter, and we are able to see some of the spicules originating on the disk just inside the limb. Bright points are frequently at the root of the disk spicules. These ``Ca II brightenings'' scuttle around at few x 10 km/s, live for 100 sec, and may be what are variously known as ``H2V grains,'' ``K2V grains,'' or "K2V bright points.'' When viewed extending over the limb, some of the spicules appear to expand horizontally or spit into two or more components, with the horizontal expansion or splitting velocities reaching 50 km/s. This work was funded by NASA's Science Mission Directorate through the Living With a Star Targeted Research and Technology Program, the Supporting Research and Program, the Heliospheric Guest Investigator Program, and the Hinode project. Title: The Cubesat Heliospheric Imaging Experiment for Space Weather Prediction Authors: DeForest, Craig; Howard, T.; Dickinson, J.; Epperly, M.; Kief, C. Bibcode: 2010AAS...21640702D Altcode: 2010BAAS...41..859D Heliospheric imaging data have been shown to improve space weather prediction by an order of magnitude, and heliospheric monitoring by the SMEI and STEREO-HI instruments have proven to be extremely useful for understanding heliospheric conditions near Earth. However, SMEI is approaching end-of-life and the STEREOs are drifting away from favorable Earth-viewing geometry just as the new solar cycle begins.

CHIME is an innovative, miniaturized, fully functional space weather heliospheric monitor that fits within the 3U CubeSat envelope and can be flown individually (as a scientific or demonstrator mission) or in a swarm (to attain operational-class reliability) at a small fraction of the cost of a conventional mission.

Here we describe the CHIME concept and its use with the automated processing pipeline AICMED to improve space weather prediction. Title: Scientific Revelations Using Heliospheric Imager Observations of Coronal Mass Ejections Authors: Howard, Timothy A.; DeForest, C.; Tappin, J. Bibcode: 2010AAS...21640616H Altcode: 2010BAAS...41..882H The recent emergence of heliospheric imagers (SMEI (2003), HI (2006)) has enabled for the first time the tracking of coronal mass ejections (CMEs) constantly across large distances, to 1 AU and beyond. This allows not only a study of the evolutionary nature of CMEs through the inner heliosphere, but also the extraction of additional three-dimensional (3-D) information that is not available in coronagraphs. This is because the linearity imposed on white light coronagraph images breaks down across large distances, allowing, with careful analysis of geometry and Thomson scattering, the extraction of 3-D structural and kinematic properties of CMEs. Additional scientific information is therefore available through heliospheric imagers. We present scientific results using such analysis on an Earth-directed event observed in November 2007. Our 3-D reconstruction analysis reveals that the event is a combination of a CME with a corotating interaction region (CIR), and we offer suggestions as to how this combined structure arose. Title: Solar Observing from Next-Generation Suborbital Platforms Authors: Deforest, C. Bibcode: 2010LPICo1534...25D Altcode: No abstract at ADS Title: Automated Feature and Event Detection with SDO AIA and HMI Data Authors: Davey, Alisdair; Martens, P. C. H.; Attrill, G. D. R.; Engell, A.; Farid, S.; Grigis, P. C.; Kasper, J.; Korreck, K.; Saar, S. H.; Su, Y.; Testa, P.; Wills-Davey, M.; Savcheva, A.; Bernasconi, P. N.; Raouafi, N. -E.; Delouille, V. A.; Hochedez, J. F. .; Cirtain, J. W.; Deforest, C. E.; Angryk, R. A.; de Moortel, I.; Wiegelmann, T.; Georgouli, M. K.; McAteer, R. T. J.; Hurlburt, N.; Timmons, R. Bibcode: 2010cosp...38.2878D Altcode: 2010cosp.meet.2878D The Solar Dynamics Observatory (SDO) represents a new frontier in quantity and quality of solar data. At about 1.5 TB/day, the data will not be easily digestible by solar physicists using the same methods that have been employed for images from previous missions. In order for solar scientists to use the SDO data effectively they need meta-data that will allow them to identify and retrieve data sets that address their particular science questions. We are building a comprehensive computer vision pipeline for SDO, abstracting complete metadata on many of the features and events detectable on the Sun without human intervention. Our project unites more than a dozen individual, existing codes into a systematic tool that can be used by the entire solar community. The feature finding codes will run as part of the SDO Event Detection System (EDS) at the Joint Science Operations Center (JSOC; joint between Stanford and LMSAL). The metadata produced will be stored in the Heliophysics Event Knowledgebase (HEK), which will be accessible on-line for the rest of the world directly or via the Virtual Solar Observatory (VSO) . Solar scientists will be able to use the HEK to select event and feature data to download for science studies. Title: The Density of Coronal Null Points from Hinode and MDI Authors: Longcope, D.; Parnell, C.; DeForest, C. Bibcode: 2009ASPC..415..178L Altcode: 2009arXiv0901.0865L Magnetic null points can be located numerically in a potential field extrapolation or their average density can be estimated from the Fourier spectrum of a magnetogram. We use both methods to compute the null point density from a quiet Sun magnetogram made with Hinode's NFI and from magnetograms from SOHO's MDI in both its high-resolution and low-resolution modes. All estimates of the super-chromospheric column density (z>1.5 Mm) agree with one another and with the previous measurements: 3×10-3 null points per square Mm of solar surface. Title: First Light with SHAZAM (the Stereoscopic High-speed Zeeman Magnetograph) Authors: Deforest, C. E.; Peterson, J. Bibcode: 2009AGUFMSH51A1265D Altcode: The Stereoscopic High-speed Zeeman Magnetograph (SHAZAM) is a visible-light solar magnetograph that is designed to deliver quantitative magnetograms as fast as possible. It uses the principle of "stereoscopic spectroscopy" to extract Zeeman splitting information throughout a 2-D focal plane, from a single six-beam exposure. SHAZAM is capable of operating at or close to the diffraction limit of its host telescope, with exposure times short enough to beat atmospheric seeing and a cadence of 8-10 Hz, fast enough for speckle reconstruction of near-diffraction-limited images. SHAZAM has been deployed at the NSO's Dunn Solar Telescope and is intended to deploy at the 1.0m Swedish Solar Telescope on La Palma and/or the new 1.6m telescope at the Big Bear Solar Observatory. It prototypes a high-speed instrument intended for installation at the planned ATST facility on Maui. We present the motivation, principle of operation, and first-light results from the first six-beam SHAZAM run at the DST in May of 2009. Title: Fluxon modeling of breakout CMEs Authors: Rachmeler, L. A.; Deforest, C. E.; DeVore, C. R.; Antiochos, S. K. Bibcode: 2009AGUFMSH41B1675R Altcode: The pivotal element of the classic breakout model of CME initiation is reconnection that occurs above inner magnetic field sheared by rotation. We research this model with the FLUX code both with and without reconnection. Without reconnection an eruption occurs after several turns have been injected into the active region. The resultant expansion or eruption is more like a kink-unstable flux rope than a classic breakout CME. By varying whether and where reconnection is allowed, we determine the location of magnetic free energy release in the breakout model. Title: Fluxon modeling of breakout CMEs Authors: Rachmeler, Laurel A.; DeForest, C. E. Bibcode: 2009shin.confE..16R Altcode: The pivotal element of the classic quadrupolar breakout model of CME initiation is reconnection that occurs above inner magnetic field sheared by rotation. We research this model with the FLUX code both with and without reconnection. Without reconnection an eruption occurs after several turns have been injected into the active region. The resultant slow expansion or eruption is more like a kink-unstable flux rope than a classic breakout CME. We expect that a global reconnection threshold within FLUX will produce a more classic breakout evolution with initial reconnection occurring across the null just above the sheared field. By varying whether and where reconnection is allowed, we determine the location of magnetic free energy release in the breakout model. Title: A Power-Law Distribution of Solar Magnetic Fields Over More Than Five Decades in Flux Authors: Parnell, C. E.; DeForest, C. E.; Hagenaar, H. J.; Johnston, B. A.; Lamb, D. A.; Welsch, B. T. Bibcode: 2009ApJ...698...75P Altcode: Solar flares, coronal mass ejections, and indeed phenomena on all scales observed on the Sun, are inextricably linked with the Sun's magnetic field. The solar surface is covered with magnetic features observed on many spatial scales, which evolve on differing timescales: the largest features, sunspots, follow an 11-year cycle; the smallest seem to follow no cycle. Here, we analyze magnetograms from Solar and Heliospheric Observatory (SOHO)/Michelson Doppler Imager (full disk and high resolution) and Hinode/Solar Optical Telescope to determine the fluxes of all currently observable surface magnetic features. We show that by using a "clumping" algorithm, which counts a single "flux massif" as one feature, all feature fluxes, regardless of flux strength, follow the same distribution—a power law with slope -1.85 ± 0.14—between 2 × 1017 and 1023 Mx. A power law suggests that the mechanisms creating surface magnetic features are scale-free. This implies that either all surface magnetic features are generated by the same mechanism, or that they are dominated by surface processes (such as fragmentation, coalescence, and cancellation) in a way which leads to a scale-free distribution. Title: Computer Vision for The Solar Dynamics Observatory Authors: Martens, Petrus C.; Angryk, R. A.; Bernasconi, P. N.; Cirtain, J. W.; Davey, A. R.; DeForest, C. E.; Delouille, V. A.; De Moortel, I.; Georgoulis, M. K.; Grigis, P. C.; Hochedez, J. E.; Kasper, J.; Korreck, K. E.; Reeves, K. K.; Saar, S. H.; Savcheva, A.; Su, Y.; Testa, P.; Wiegelmann, T.; Wills-Davey, M. Bibcode: 2009SPD....40.1711M Altcode: NASA funded a large international consortium last year to produce a comprehensive system for automated feature recognition in SDO images. The data we consider are all AIA and EVE data plus surface magnetic field images from HMI. Helioseismology is addressed by another group.

We will produce robust and very efficient software modules that can keep up with the relentless SDO data stream and detect, trace, and analyze a large number of phenomena, including: flares, sigmoids, filaments, coronal dimmings, polarity inversion lines, sunspots, X-ray bright points, active regions, coronal holes, EIT waves, CME's, coronal oscillations, and jets. In addition we will track the emergence and evolution of magnetic elements down to the smallest features that are detectable, and we will also provide at least four full disk nonlinear force-free magnetic field extrapolations per day.

A completely new software element that rounds out this suite is a trainable feature detection module, which employs a generalized image classification algorithm to produce the texture features of the images analyzed. A user can introduce a number of examples of the phenomenon looked and the software will return images with similar features. We have tested a proto-type on TRACE data, and were able to "train" the algorithm to detect sunspots, active regions, and loops. Such a module can be used to find features that have not even been discovered yet, as, for example, sigmoids were in the pre-Yohkoh era.

Our codes will produce entries in the Helio Events Knowledge base, and that will permit users to locate data on individual events as well as carry out statistical studies on large numbers of events, using the interface provided by the Virtual Solar Observatory. Title: First Results from a Novel Magnetograph (SHAZAM) Authors: DeForest, Craig; Rimmele, T.; Berger, T.; Peterson, J. Bibcode: 2009SPD....40.3301D Altcode: The magnetic energy flux through the Sun's surface is dominated by small features at all currently observable spatial scales; hence there is a strong need to improve the spatial resolution of magnetic measurements, which are increasingly photon starved as telescopes improve. The Solar High-speed Zeeman Magnetograph (SHAZAM) is a line-of-sight magnetograph based on the principle of spectral stereoscopy. It is designed to acquire magnetograms quickly enough to beat image fluctuations due to both solar evolution and terrestrial seeing, even on scales under 100 km on the Sun. It is over 100x more photon efficient than existing quantitative magnetographs such as SOHO/MDI. We present first results from an observing run at the National Solar Observatory's Dunn Solar Telescope in May 2009, hopefully including near-diffraction-limited, time resolved magnetogram sequences with better than 150km resolution on the surface of the Sun. Title: Quadrupolar CME Initiation with Flux Authors: Rachmeler, Laurel; DeForest, C. E. Bibcode: 2009SPD....40.3706R Altcode: We present initial results of reconnectionless fluxon simulations of a full sun quadrupolar system for CME initiation. This research sets a baseline control case for studying the specific effects of reconnection in the the breakout reconnection CME model. We are studying this system with no reconnection, with a globally determined resistivity, and with targeted reconnection below and above the inner sheared arcade to determine when and where the magnetic energy is released in the classic breakout scenario. Title: A Power-law Distribution of Solar Magnetic Fields Over More Than Five Decades in Flux Authors: Parnell, Clare; DeForest, C. E.; Hagenaar, H. J.; Johnston, B. A.; Lamb, D. A.; Welsch, B. T. Bibcode: 2009SPD....40.0603P Altcode: The surface of the Sun is covered with magnetic features observed on many spatial scales, which evolve on differing time scales: the largest features, sunspots, follow an 11 year cycle; the smallest apparently follow no cycle. Magnetograms from SoHO/MDI (full disk and high-resolution) and Hinode/SOT are analysed to determine the fluxes of all currently observable surface magnetic features. To identify features we use a 'clumping' algorithm, which defines a single feature as a group of contiguous, same-sign pixels, each of which exceeds an absolute flux cutoff. We show that, using this feature identification method, all feature fluxes, regardless of flux strength, follow the same distribution - a power-law with slope -1.85±0.14 - between 2x 1017 and 1023 Mx. This result implies that the processes that determine the spatial structure of surface magnetic features are scale-free. Hence, suggesting that either all surface magnetic features are generated by the same mechanism, or that their spatial structure is dominated by processes in the interior or at the surface (e.g., fragmentation, coalescence and cancellation) that produce a scale-free distribution. We will discuss the likelihood of these two mechanisms for generating the powerlaw distribution of feature fluxes. Title: Reconnectionless CME Eruption: Putting the Aly-Sturrock Conjecture to Rest Authors: Rachmeler, L. A.; DeForest, C. E.; Kankelborg, C. C. Bibcode: 2009ApJ...693.1431R Altcode: 2008arXiv0812.3199R We demonstrate that magnetic reconnection is not necessary to initiate fast Coronal mass ejections (CMEs). The Aly-Sturrock conjecture states that the magnetic energy of a given force-free boundary field is maximized when the field is open. This is problematic for CME initiation because it leaves little or no magnetic energy to drive the eruption, unless reconnection is present to allow some of the flux to escape without opening. Thus, it has been thought that reconnection must be present to initiate CMEs. This theory has not been subject to rigorous numerical testing because conventional magnetohydrodynamics (MHD) numerical models contain numerical diffusion, which introduces uncontrolled numerical reconnection. We use a quasi-Lagrangian simulation technique to run the first controlled experiments of CME initiation in the complete lack of reconnection. We find that a flux rope confined by an arcade, when twisted beyond a critical amount, can escape to an open state, allowing some of the surrounding arcade to shrink, and releasing magnetic energy from the global field. This mechanism includes a true ideal MHD instability. We conclude that reconnection is not a necessary trigger for fast CME eruptions. Title: Solar Coronal Structure and Stray Light in TRACE Authors: DeForest, C. E.; Martens, P. C. H.; Wills-Davey, M. J. Bibcode: 2009ApJ...690.1264D Altcode: 2008arXiv0808.3980D Using the 2004 Venus transit of the Sun to constrain a semiempirical point-spread function (PSF) for the TRACE EUV solar telescope, we have measured the effect of stray light in that telescope. We find that 43% of 171 Å EUV light that enters TRACE is scattered, either through diffraction off the entrance filter grid or through other nonspecular effects. We carry this result forward, via known-PSF deconvolution of TRACE images, to identify its effect on analysis of TRACE data. Known-PSF deconvolution by this derived PSF greatly reduces the effect of visible haze in the TRACE 171 Å images, enhances bright features, and reveals that the smooth background component of the corona is considerably less bright (and hence more rarefied) than might otherwise be supposed. Deconvolution reveals that some prior conclusions about the Sun appear to have been based on stray light in the images. In particular, the diffuse background "quiet corona" becomes consistent with hydrostatic support of the coronal plasma; feature contrast is greatly increased, possibly affecting derived parameters such as the form of the coronal heating function; and essentially all existing differential emission measure studies of small features appear to be affected by contamination from nearby features. We speculate on further implications of stray light for interpretation of EUV images from TRACE and similar instruments, and advocate deconvolution as a standard tool for image analysis with future instruments. Title: Generation, Evolution and Destruction of Solar Magnetic Fields Authors: Keil, Stephen; Rimmele, Thomas; DeForest, Craig Bibcode: 2009astro2010S.153K Altcode: No abstract at ADS Title: Quiet-Sun: A Comparison of MDI and SOT Fluxes Authors: Parnell, C. E.; Deforest, C. E.; Hagenaar, H. J.; Lamb, D. A.; Welsch, B. T. Bibcode: 2008ASPC..397...31P Altcode: The SOT-NFI on Hinode has both higher resolution and better sensitivity than MDI on SOHO. Line-of-sight magnetograms of the quiet Sun taken simultaneously by both MDI and SOT are investigated to show how the observed flux differs between the two instruments. We find that: (i) the total unsigned flux observed by SOT is approximately 50% greater than that observed by MDI and (ii) the total signed flux remains approximately constant. Thus, the extra flux observed by SOT is made up of equal amounts of positive and negative flux. By comparing the observed flux distributions from MDI and SOT we find that the extra flux is contained in features with fluxes less than the smallest observed by MDI. Indeed, the smallest features in SOT have just ≥ 10^{16} Mx, a factor of thirty less than the smallest observed by MDI.

The distributions of feature fluxes observed by the two instruments are also compared. We find that by using a `clumping' algorithm, which counts a single `flux massif' as one feature, the fluxes in MDI and SOT follow the same distribution - a power-law - between 2× 10^{17} and 10^{20} Mx. Thus, the mechanism producing network and intranetwork features appears to be the same. Furthermore, the power-law index of this distribution is found to be -1.85. This value is neither the Kolomogrov -5/3 slope of hydrodynamic turbulence nor the Krichenen -2 slope of magneto-hydrodynamic turbulence, although both of these numbers may be within the error bars of our analysis. Title: WHI Targeted Campaigns on Coronal Holes and Quiet Sun: High Resolution Observations of the Lower Atmosphere With IBIS Authors: Cauzzi, G.; Reardon, K. P.; Rimmele, T.; Tritschler, A.; Uitebroek, H.; Woeger, F.; Deforest, C.; McIntosh, S. Bibcode: 2008AGUSMSH51A..02C Altcode: The Interferometric BIdimensional Spectrometer (IBIS) is a dual Fabry-Perot instrument installed at the Dunn Solar Telescope that allows two-dimensional spectroscopic observations in a variety of spectral lines. The IBIS/DST will participate in the WHI targeted campaigns on coronal holes (April 3-9) and quiet Sun dynamics (April 10-16) performing simultaneous high-resolution observations of the dynamics of the photosphere and chromosphere in the coordinated targets. The aim is to obtain insights on the role of the lower atmosphere's dynamics and energetics into the structuring of the coronal plasma and, possibly, into the origin of the solar wind. In this paper we will present the observations obtained as well as first results, and attempt to relate them with recent work performed on quiet Sun chromospheric dynamics. Title: The Small-Scale Field Measured With Hinode/SOT and Feature Tracking: Where is the mixed- polarity flux? Authors: Deforest, C. E.; Lamb, D. A.; Berger, T.; Hagenaar, H.; Parnell, C.; Welsch, B. Bibcode: 2008AGUSMSP51D..01D Altcode: We report on the results of the first feature tracking study of the solar magnetic field with Hinode/SOT. We processed a SOT Na-D line-of-sight magnetogram sequence with five different magnetic tracking codes. The SOT data allow us to probe the evolving magnetic field on the granular scale for hours at a time, something that was not possible with either ground-based observations (which are limited to short periods of good seeing) or prior space-based observations (which are limited to arcsecond spatial scales). We find that the field is much less mixed than previously supposed: while Hinode resolves small-scale structure within features that, to SOHO/MDI, would appear as monolithic flux concentrations, this substructure has but a single sign. Furthermore, the average distance between identifiable flux concentrations of opposite sign remains nearly unchanged at the higher resolution, a result that is quite surprising in light of the common picture of a sea of strong mixed-polarity flux concentrations dotting the inter-granular lanes. We discuss possible mechanisms for this surprising result, and implications for the small-scale dynamo. Title: The Effect of Scattered Light on EUV Coronal Observations Authors: Deforest, C. E. Bibcode: 2008AGUSMSP54A..03D Altcode: I have measured the stray light profile of the TRACE 171 A channel using the 2004 Venus occultation data. I find that ~35 percent of the incident EUV is scattered into a kernel with over 200" diameter. This is nearly twice the estimated energy of the known diffraction pattern from the TRACE aluminum filter support grids. Deconvolving with the fitted PSF greatly improves contrast in TRACE images and may affect scientific results derived from them. I conclude that PSF measurement and deconvolution is necessary for correct interpretation of images not just from TRACE but other spaceborne telescopes, note that the night-time and ground-based solar observing communities have already adopted stray light deconvolution as a standard procedure, and call for deconvolution as a standard part of the data reduction pipeline from future solar space missions. Title: Modeling Coronal Jets with FLUX Authors: Rachmeler, L. A.; Pariat, E.; Antiochos, S. K.; Deforest, C. E. Bibcode: 2008AGUSMSP43B..01R Altcode: We report on a comparative study of coronal jet formation with and without reconnection using two different simulation strategies. Coronal jets are features on the solar surface that appear to have some properties in common with coronal mass ejections, but are less energetic, massive, and broad. Magnetic free energy is built up over time and then suddenly released, which accelerates plasma outward in the form of a coronal jet. We compare results from the ARMS adaptive mesh and FLUX reconnection-less codes to study the role of reconnection in this system. This is the first direct comparison between FLUX and a numerical model with a 3D spatial grid. Title: Solar Magnetic Tracking. II. The Apparent Unipolar Origin of Quiet-Sun Flux Authors: Lamb, D. A.; DeForest, C. E.; Hagenaar, H. J.; Parnell, C. E.; Welsch, B. T. Bibcode: 2008ApJ...674..520L Altcode: We investigate the origin of small-scale flux concentrations in the quiet Sun. In apparent violation of the physical requirement for flux balance, 94% of the features containing newly detected flux are unipolar at a resolution of 1.2''. We analyze 2619 of these apparent unipolar emergences in an image sequence from the SOHO MDI magnetograph and compare the ensemble average to a model of asymmetric bipolar emergence that could in principle hide opposing flux under the noise floor of MDI. We examine the statistical consequences of this mechanism and find that it cannot be responsible for more than a small fraction of the unipolar emergences. We conclude that the majority of the newly detected flux in the quiet Sun is instead due to the coalescence of previously existing but unresolved flux into concentrations that are large and strong enough to be detected. We estimate the rate of coalescence into arcsecond-scale magnetic features averaged over the solar surface to be 7 × 1021 Mx hr-1, comparable to the reported flux injection rate due to ephemeral regions. This implies that most flux in the solar network has been processed by very small scale shredding, emergence, cancellation, and/or coalescence that is not resolved at 1.2'', and it suggests that currently unresolved emergences may be at least as important as ephemeral region emergences to the overall flux budget. Title: The effect of reconnection on a confined flux rope Authors: Rachmeler, L. A.; Deforest, C. E.; Kankelborg, C. C. Bibcode: 2007AGUFMSH31A0233R Altcode: Coronal mass ejections are among the most energetic events in our solar system, but their initiation mechanisms are still not well known. One possibility is loss of stability of a twisted flux rope confined by an overlying arcade. We present here a continuation of our research studying the role of reconnection on this system. We examine the relationship between critical-current reconnection and stability of a simple confined flux rope in simulations free from numerical reconnection. The current work focuses on imposing various reconnection rates on the system to determine how reconnection effects the stability of the confined rope. Title: Feature Tracking of Hinode Magnetograms Authors: Lamb, D.; Deforest, C. E.; Hagenaar, H. J.; Parnell, C. E.; Welsch, B. T. Bibcode: 2007AGUFMSH53A1066L Altcode: We present results of applying feature tracking to a sequence of Hinode magnetograms. The single line wing Na D 5896 magnetograms have a high signal-to-noise ratio, allowing the detection of flux approximately 30 times weaker than in MDI magnetograms. We find evidence that, even with Hinode's improved resolution and sensitivity, we do not always detect the bipolar emergence of new magnetic flux. This suggests that we have not reached the ultimate resolution to observe the fundamental flux generation processes in the photosphere. Title: Solar Magnetic Tracking. I. Software Comparison and Recommended Practices Authors: DeForest, C. E.; Hagenaar, H. J.; Lamb, D. A.; Parnell, C. E.; Welsch, B. T. Bibcode: 2007ApJ...666..576D Altcode: 2007arXiv0704.2921D Feature tracking and recognition are increasingly common tools for data analysis, but are typically implemented on an ad hoc basis by individual research groups, limiting the usefulness of derived results when selection effects and algorithmic differences are not controlled. Specific results that are affected include the solar magnetic turnover time, the distributions of sizes, strengths, and lifetimes of magnetic features, and the physics of both small scale flux emergence and the small-scale dynamo. In this paper, we present the results of a detailed comparison between four tracking codes applied to a single set of data from SOHO/MDI, describe the interplay between desired tracking behavior and parameterization tracking algorithms, and make recommendations for feature selection and tracking practice in future work. Title: Are ``EIT Waves'' Fast-Mode MHD Waves? Authors: Wills-Davey, M. J.; DeForest, C. E.; Stenflo, J. O. Bibcode: 2007ApJ...664..556W Altcode: 2007arXiv0704.2828W We examine the nature of large-scale, coronal, propagating wave fronts (``EIT waves'') and find they are incongruous with solutions using fast-mode MHD plane-wave theory. Specifically, we consider the following properties: nondispersive single pulse manifestations, observed velocities below the local Alfvén speed, and different pulses which travel at any number of constant velocities, rather than at the ``predicted'' fast-mode speed. We discuss the possibility of a soliton-like explanation for these phenomena, and show how it is consistent with the above-mentioned aspects. Title: Fluxon Modeling of Eruptive Events With and Without Reconnection Authors: DeForest, Craig; Rachmeler, L.; Davey, A.; Kankelborg, C. Bibcode: 2007AAS...210.5305D Altcode: 2007BAAS...39..165D Fluxon MHD models represent the coronal magnetic field as a "skeleton" of discretized field lines. This quasi-Lagrangian approach eliminates numerical resistivity and allows 3-D time-dependent plasma simulation in a desktop workstation.Using our fluxon code, FLUX, we have demonstrated that ideal MHD instabilities can drive fast eruptive events even in the complete absence of magnetic reconnection. The mechanism ("herniation") is probably not the main driver of fast CMEs but may be applicable to microjets, macrospicules, or other small scale events where vortical flows are present in the solar atmosphere. In this presentation, we use time-dependent simulations to demonstrate energy release in several idealized plasma systems with and without magnetic reconnection.This work was funded by NASA's LWS and SHP-SR&T programs. Title: On the Size of Structures in the Solar Corona Authors: DeForest, C. E. Bibcode: 2007ApJ...661..532D Altcode: 2006astro.ph.10178D Fine-scale structure in the corona appears not to be well resolved by current imaging instruments. Assuming this to be true offers a simple geometric explanation for several current puzzles in coronal physics, including the apparent uniform cross section of bright threadlike structures in the corona, the low EUV contrast (long apparent scale height) between the top and bottom of active region loops, and the inconsistency between loop densities derived by spectral and photometric means. Treating coronal loops as a mixture of diffuse background and very dense, unresolved filamentary structures addresses these problems with a combination of high plasma density within the structures, which greatly increases the emissivity of the structures, and geometric effects that attenuate the apparent brightness of the feature at low altitudes. It also suggests a possible explanation for both the surprisingly high contrast of EUV coronal loops against the coronal background, and the uniform ``typical'' height of the bright portion of the corona (about 0.3 Rsolar) in full-disk EUV images. Some ramifications of this picture are discussed, including an estimate (10-100 km) of the fundamental scale of strong heating events in the corona. Title: CMEs Driven by Flux Rope Herniation Authors: Rachmeler, Laurel; DeForest, C. E. Bibcode: 2007AAS...210.2908R Altcode: 2007BAAS...39R.138R Much numerical work has been done on the magnetic kink instability as a CME driver, but thus far it is all subject to numerical diffusion which can bias results toward eruption. We present further results on this instability in the absence of reconnection. We have found that a highly twisted metastable magnetic configuration consisting of a fluxrope contained by an arcade is capable of creating an impulsive CME through herniation and without any reconnection. Title: Magnetic Network Formation Due to Sub-arcsecond Flux Processing Authors: Lamb, Derek; DeForest, C. E.; Parnell, C. E.; Hagenaar, H. J.; Welsch, B. T. Bibcode: 2007AAS...210.9213L Altcode: 2007BAAS...39Q.210L Kinematic models of solar magnetic network formation typically employ the breakup of ephemeral regions by granular and supergranular flow. We show that the coalescence of sub-arcsecond-scale magnetic flux concentrations into features detectable with MDI is responsible for injecting as much flux into the magnetic network as the published emergence rate of ephemeral regions. We also show that the few fresh bipoles we do detect have no preferential alignment, and thus violate Joy's law at the arcsecond scale. These two items suggest that at least half of the flux that makes its way into the network has been processed at spatial scales below 1 arcsecond, indicative of a local dynamo. Title: The Sensitivity of Hybrid Differential Stereoscopy for Spectral Imaging Authors: DeForest, Craig E.; Kankelborg, Charles C. Bibcode: 2007arXiv0704.2058D Altcode: 2007arXiv0704.2058K Stereoscopic spectral imaging is an observing technique that affords rapid acquisition of limited spectral information over an entire image plane simultaneously. Light from a telescope is dispersed into multiple spectral orders, which are imaged separately, and two or more of the dispersed images are combined using an analogy between the (x,y,\lambda) spectral data space and conventional (x,y,z) three-space. Because no photons are deliberately destroyed during image acquisition, the technique is much more photon-efficient in some observing regimes than existing techniques such as scanned-filtergraph or scanned-slit spectral imaging. Hybrid differential stereoscopy, which uses a combination of conventional cross-correlation stereoscopy and linear approximation theory to extract the central wavelength of a spectral line, has been used to produce solar Stokes-V (line-of-sight) magnetograms in the 617.34 nm Fe I line, and more sophisticated inversion techniques are currently being used to derive Doppler and line separation data from EUV images of the solar corona collected in the neighboring lines of He-II and Si-XI at 30.4 nm. In this paper we develop an analytic a priori treatment of noise in the line shift signal derived from hybrid differential stereoscopy. We use the analysis to estimate the noise level and measurement precision in a high resolution solar magnetograph based on stereoscopic spectral imaging, compare those estimates to a test observation made in 2003, and discuss implications for future instruments. Title: Fluxon modeling of low-beta plasmas Authors: Deforest, C. E.; Kankelborg, C. C. Bibcode: 2007JASTP..69..116D Altcode: 2007JATP...69..116D; 2006astro.ph..9508D We have developed a new, quasi-Lagrangian approach for numerical modeling of magnetohydrodynamics in low to moderate β plasmas such as the solar corona. We introduce the concept of a “fluxon”, a discretized field line. Fluxon models represent the magnetic field as a skeleton of such discrete field lines, and interpolate field values from the geometry of the skeleton where needed, reversing the usual direction of the field line transform. The fluxon skeleton forms the grid for a collection of 1-D Eulerian models of plasma along individual flux tubes. Fluxon models have no numerical resistivity, because they preserve topology explicitly. Our prototype code, FLUX, is currently able to find 3-D nonlinear force-free field solutions with a specified field topology, and work is ongoing to validate and extend the code to full magnetohydrodynamics. FLUX has significant scaling advantages over conventional models: for “magnetic carpet” models, with photospheric line-tied boundary conditions, FLUX simulations scale in complexity like a conventional 2-D grid although the full 3-D field is represented. The code is free software and is available online. In this current paper we introduce fluxons and our prototype code, and describe the course of future work with the code. Title: Fluxon Modeling of Active Region Evolution Authors: Deforest, C. E.; Kankelborg, C. C.; Davey, A. R.; Rachmeler, L. Bibcode: 2006AGUFMSH31B..07D Altcode: We present current results and status on fluxon modeling of free energy buildup and release in active regions. Our publicly available code, FLUX, has the unique ability to track magnetic energy buildup with a truly constrained topology in evolving, nonlinear force-free conditions. Recent work includes validation of the model against Low &Lou force-free field solutions, initial evolution studies of idealized active regions, and inclusion of locally parameterized reconnection into the model. FLUX is uniquely able to simulate complete active regions in 3-D on a single workstation; we estimate that a parallelized fluxon model, together with computer vision code to ingest solar data, could run faster than real time on a cluster of \textasciitilde 30 CPUs and hence provide a true predictive space weather model in the style of predictive simulations of terrestrial weather. Title: CME Initiation due to the Kink Instability in the Absence of Reconnection Authors: Rachmeler, L. A.; Deforest, C. E. Bibcode: 2006AGUFMSH33B0402R Altcode: We present results from a controlled numerical experiment to determine whether CME onset requires reconnection or can be driven primarily by loss of magnetic equilibrium. We have simulated kink-unstable CME liftoff in the complete absence of numerical reconnection by inducing twist in a line-tied photospheric boundary using a fluxon simulation code. Our initial results suggest that it is possible to drive slow CMEs entirely via the kink instability even in the absence of a large reconnection event such as breakout or a solar flare. We further describe ongoing work, which includes studying the relative importance of reconnection and of mass draining on CME onset. Title: Goals and Progress of the LWS Focused Science Topic on the CME--ICME Connection Authors: Mikic, Z.; Deforest, C.; Devore, R.; Georgoulis, M.; Jackson, B.; Nitta, N.; Pizzo, V.; Odstrcil, D. Bibcode: 2006AGUFMSH21B..05M Altcode: Our team addresses the NASA Living With a Star (LWS) Focused Science Topic "to determine the solar origins of the plasma and magnetic flux observed in an interplanetary Coronal Mass Ejection (ICME)." In short, this team is examining the CME--ICME connection. Our team was formed as a result of awards from the LWS Targeted Research &Technology competition in the fall of 2004. Our team is investigating the detailed relationship between the plasma and magnetic fields in active regions, the source regions of CMEs, and subsequent in situ measurements in interplanetary magnetic clouds. We plan to study this connection through detailed numerical simulations of CME initiation and propagation, theoretical investigations, and studies of the properties of active regions, CMEs, and magnetic clouds. We will discuss the goals of our team, how it fits into NASA's missions, and our progress so far. Research supported by NASA's Living With a Star Program. Title: On the Origin of "Unipolar" Magnetic Flux Emergence: The Emergence you See is not the True Emergence Authors: Lamb, D. A.; Deforest, C. E. Bibcode: 2006ESASP.617E..70L Altcode: 2006soho...17E..70L No abstract at ADS Title: Active Region Loops: Not So Strange After All Authors: DeForest, Craig Bibcode: 2006SPD....37.0122D Altcode: 2006BAAS...38..219D Active region loops are enigmatic. Despite a great deal of work many pecularities remain hard to explain, such as their nonthermal apparent scale height, apparent uniform thickness, extreme thermal inhomogeneity, and rapid evolution on timescales shorter than the apparent cooling time. All of these effects can be explained via the assumption that bright threads in active regions do in fact follow the morphology of the force-free field (i.e. do not have uniform thickness) but are not fully resolved by TRACE. I find that nearly-hydrostatic, force-free active region loops with isolated localized heating are the simplest physical scenario for active region loop formation. In this scenario, the threads are >10x more dense than the surrounding media, with a radiative cooling time as short as 30 seconds; the anomalous apparent scale heights are caused by a geometric effect on unresolved (or poorly resolved) spatial scales. In addition, the picture provides a ready explanation both for threads' rapid appearance and disappearance in TRACE movies and also for the surprising existence of transient, smooth, threaded, cool active region loops in TRACE FUV images. Whether this scenario proves true, it serves to demonstrate an important geometrical effect that, if ignored, can cause large problems for interpretation of EUV and FUV active region images. Title: "EIT Waves" as Coronal Solitons: Explaining The Nature of Large-Scale Coronal Pulse Waves Authors: Wills-Davey, Meredith; DeForest, C. E.; Stenflo, J. O. Bibcode: 2006SPD....37.1006W Altcode: 2006BAAS...38..238W We find that a soliton solution is applicable in a fully non-linear, coronal MHD environment, and the compressive component of this solution results in a pulse wave similar to the large-scale coronal propagating wavefronts (``EIT waves'') observed by the SOHO-EIT and TRACE telescopes. Properties of EIT wave waves that have previously appeared incongruous using plane-wave theory are resolved in the context of the soliton solution. Specifically, we show: why the observed wave speed can be expected to be less than the local Alfvén speed, how a wave pulse can instigate loop oscillations, and how a single pulse can be channeled to propagate through the lower corona. We also discuss the nature of likely triggers, and find that coronal mass ejections are an ideal wave instigator. Title: The Origin of "Unipolar" Magnetic Flux Emergence Authors: Lamb, Derek; DeForest, C. E. Bibcode: 2006SPD....37.0706L Altcode: 2006BAAS...38..228L Automated tracking of magnetograms provides the ability to detect magnetic features in an unbiased manner. Such feature tracking shows many apparent unipolar flux emergences. Flux conservation dictates that this cannot be a real phenomenon and thus must be due to processes below the detection limit of routine measurements. We use large numbers of these apparent unipolar events to distinguish between two models of small-scale magnetic flux formation. We find that asymmetric flux emergence, in which the poles of the emerging flux tube have different cross sections or incidence angles at the photosphere, can account for at most half of the events. Convergence of like-polarity poles due to flows at sub-resolution scales provides a better explanation for the majority of the events. Title: Exploring the Dynamics of the Solar Corona with RAISE (Rapid Acquisition Imaging Spectrograph Experiment) Authors: Gantner, Brennan; Hassler, D.; DeForest, C. Bibcode: 2006SPD....37.0603G Altcode: 2006BAAS...38Q.226G The Rapid Acquisition Imaging Spectrograph Experiment (RAISE) instrument will launch fall of 2006 on a NASA sounding rocket and contains an extremely high speed scanning-slit imaging spectrograph to observe and analyze dynamics and heating of the solar chromosphere and corona on time scales as short as 100 ms, with TRACE-like spatial resolution and a velocity sensitivity of 1 km/sec. High speed imaging from TRACE has shown that rapid motions and reconnection are central to the physics of the transition region and corona, but cannot resolve the differences between propagating phenomena and bulk motion. SoHO/CDS and SoHO/SUMER have yielded intriguing measurements of motion and heating in the solar atmosphere, and Solar-B/EIS will capture EUV spectra of flares in progress; but no currently operating instrument can capture spectral information in the chromosphere, transition region, or cool corona on the 1-10 Hz time scale required for few-second cadence spectral imaging or rapid wave motion studies. RAISE is uniquely suited to exploring this hard-to-reach domain. The complete investigation will probe three general topics that are accessible only with our instrument's unique capabilities, and that can be advanced with a single rocket flight: 1) Small-scale multithermal dynamics in active-region loops; 2) the strength, spectrum, and location of high frequency waves in the solar atmosphere; and 3) the nature of transient brightenings in the solar network. Title: Exploring High Time Resolution Coronal Dynamics with the Rapid Acquisition Imaging Spectrograph (RAISE) Sounding Rocket Program Authors: Hassler, Donald W.; DeForest, C. E.; McIntosh, S.; Slater, D.; Ayres, T.; Thomas, R.; Scheuhle, U.; Michaelis, H.; Mason, H. Bibcode: 2006SPD....37.3706H Altcode: The Rapid Acquisition Imaging Spectrograph (RAISE) is a next-generation high resolution imaging spectrograph to study the dynamics of the solar chromosphere and corona on time scales as short as 100 ms. High speed imaging from TRACE has shown that rapid motions and reconnection are central to the physics of the transition region and corona, but cannot resolve the differences between propagating phenomena and bulk motion. SoHO/CDS and SoHO/SUMER have yielded intriguing measurements of motion and heating in the solar atmosphere, and Solar-B/EIS will capture EUV spectra of flares in progress; but no currently planned instrument can capture spectral information in the chromosphere, transition region, or cool corona on the 1-10 Hz time scale required for few-second cadence spectral imaging or rapid wave motion studies. RAISE is uniquely suited to exploring this hard-to-reach domain.The first flight of RAISE is scheduled for October 24, 2006 (Flight 36.219 US) and will focus on the study of high frequency, small-scale dynamics of active region structures and the high frequency wave structure associated with these active regions. Title: Is Reconnection Necessary for Kinked CME Onset? Authors: Rachmeler, Laurel; DeForest, C. E.; Gibson, S. E.; Fan, Y. Bibcode: 2006SPD....37.0902R Altcode: 2006BAAS...38..236R We present initial results from a controlled numerical experiment to determine whether CME onset requires reconnection or can be driven primarily by loss of plasma equilibrium. The early onset of the kink instability proceeds with little reconnection in traditional MHD simulations, but still at a nonzero rate. After the initial onset of the instability, reconnection proceeds rapidly across the newly formed current sheet, contributing to the ejection of the kink. We have simulated the kink instability driven purely by loss of plasma equilibrium - in the absence of numerical reconnection - as an early step to understanding the role of reconnection in CME evolution. Title: Relationship between Solar Wind and Coronal Heating: Scaling Laws from Solar X-Rays Authors: Schwadron, N. A.; McComas, D. J.; DeForest, C. Bibcode: 2006ApJ...642.1173S Altcode: Pevtsov et al. recently showed that the luminosity of solar and stellar X-rays from closed magnetic structures scales nearly linearly with magnetic flux over 12 decades. We show here that the total power available to accelerate the solar wind also scales linearly with magnetic flux, provided that its sources inject a roughly constant energy per particle prior to losses from heat conducted by electrons into radiation. Using a recently developed model of the solar wind energy source and particle source, we calculate the available solar wind power and convert it into an equivalent X-ray luminosity to explore whether the same process that drives solar wind may also power coronal heating. The quantitative results agree remarkably well with the Pevtsov et al. X-ray observations and with GOES X-ray observations over almost two solar cycles from 1985 to 2004. The model for the solar wind energy and particle source relies on the continual reconfiguration of the supergranular network through the emergence of small bipolar or more complex closed magnetic fields. This naturally leads to an energy flux proportional to field strength on large-scale field structures with field strengths larger than the emerging flux. We conclude that the sources of energy for the solar wind and coronal heating are linked, likely through the emergence of new magnetic flux that continually reconfigures large-scale solar magnetic fields and powers and heats the corona. Title: Initial fluxon models of CME onset: loss-of-equilibrium, breakout, tether-cutting Authors: Deforest, C. Bibcode: 2005AGUFMSH13A0277D Altcode: I will present results from initial models of CME onset using a new force-free magnetic evolution code, FLUX, that uses the novel fluxon approach to MHD modeling. FLUX is a quasi-Lagrangian solver that is free of numerical reconnection and that I am making available as free software. It is currently suitable for studying evolving force-free equilibria in the presence of only controlled reconnection; development work is ongoing to add plasma static and dynamic forces. I plan to consider three simple configurations typical of three current genres of CME onset model: loss of equilibrium under smooth motion by the photosphere; "tether-cutting" (reconnection of a containment field underneath a twisted prominence field); and "breakout" (reconnection of a containment field above a twisted prominence field). In each case I will estimate the magnetic energy available to accelerate mass, and discuss the resulting shape of the remnant open field regions ("dimming regions") after liftoff. Title: On the Magnetic Correspondence between the Photosphere and the Heliosphere Authors: Deforest, C. E.; Hassler, D. M.; Schwadron, N. A. Bibcode: 2005SoPh..229..161D Altcode: The solar magnetic field maps every point in the corona to a corresponding place on the solar surface. Identifying the magnetic connection map is difficult at low latitudes near the heliospheric current sheet, but remarkably simple in coronal hole interiors. We present a simple analytic magnetic model (`pseudocurrent extrapolation') that reproduces the global structure of the corona, with significant physical advantages over other nearly analytic models such as source-surface potential field extrapolation. We use the model to demonstrate that local horizontal structure is preserved across altitude in the central portions of solar coronal holes, up to at least 30 Rs, in agreement with observations. We argue that the preserved horizontal structure may be used to track the magnetic footpoint associated with the location of a hypothetical spacecraft traveling through the solar corona, to relate in situ measurements of the young solar wind at ∼10-30 Rs to particular source regions at the solar surface. Further, we discuss the relationship between readily observable geometrical distortions and physical parameters of interest such as the field-aligned current density. Title: Destruction Mechanisms of Quiet-Sun Magnetic Flux Authors: Lamb, D. A.; Deforest, C. E.; Hagenaar, H. J.; Parnell, C. E.; Welsch, B. T. Bibcode: 2005AGUSMSP41B..02L Altcode: We use SWAMIS, a freely available magnetic feature tracking suite, to analyze the destruction of solar small-scale magnetic flux. We track a sequence of high resolution MDI magnetograms to find the destruction rates in a patch of quiet sun. We state criteria for defining the individual magnetochemical destruction mechanisms of merging, cancellation, and disappearance, and determine the contribution of each process to the removal of detected flux from the photosphere. Destruction mechanisms are important to determine because, together with formation mechanisms, they provide information as to the nature of the small-scale dynamo. We present preliminary results and discuss the implications of these rates on models of quiet-sun magnetic flux generation. Title: High-Frequency Waves Detected in the Solar Atmosphere Authors: DeForest, C. E. Bibcode: 2004ApJ...617L..89D Altcode: A spectrum of weakly guided waves in the solar atmosphere at frequencies as high as 100 mHz (10 s period) has been detected with high-cadence solar image sequences from the Transition Region and Coronal Explorer (TRACE) spacecraft. The waves are visible in the TRACE 1600 Å far-UV passband and were detected as faint ridges in an energy spectrum produced by Fourier transformation of subfields of TRACE image sequences. They have phase speeds as high as 1 Mm s-1 and group speeds of ~100 km s-1. From the 1600 Å data alone, it is not possible to determine whether the waves are in the chromosphere or transition region. The waves are not energetically significant to the chromosphere but may be significant in the transition region. Two possible excitation mechanisms, small-scale magnetic reconnection or chromospheric shock formation, are identified and will guide future work. The waves may prove to be a useful probe into local conditions and energy release into the solar atmosphere. Title: Stereoscopic Spectroscopy for Efficient Spectral Imaging and Magnetography Authors: DeForest, Craig; Elmore, D. F.; Bradford, M. P.; Elrod, J.; Gilliam, D. L. Bibcode: 2004ApJ...616..600D Altcode: Stereoscopic imaging spectroscopy is a novel technique that uses multiple spectral orders and stereoscopic reconstruction to eliminate the need for a slit in a dispersive spectrograph, potentially increasing photon efficiency by 1-2 orders of magnitude compared with conventional spectral imaging. We present advances in stereoscopic reconstruction, allowing detection of the first moments of a spectral line simultaneously over a complete two-dimensional image plane. Using the Advanced Stokes Polarimeter on the Dunn Solar Telescope at the National Solar Observatory, we have created the first solar magnetograms made with this technique. With a simple prototype optical layout, we were able to generate Stokes V magnetograms using the Fe I photospheric absorption line at 617.34 nm (6173.4 Å). We calculate that an optimized instrument using this technique could acquire solar magnetograms with ~10 G rms shot noise in 150 ms using this spectral line at the host telescope's diffraction limit. Stereoscopic techniques are useful not only for the solar photosphere but also for photon-starved imaging spectroscopy in general. Title: High Time Cadence Observations with the Rapid Acquisition Imaging Spectrograph (RAISE) Rocket Program Authors: Ayres, T. R.; Hassler, D. M.; Slater, D.; DeForest, C. E.; Mason, H.; McIntosh, S.; Thomas, R. J. Bibcode: 2004AAS...204.9704A Altcode: 2004BAAS...36..828A The Rapid Acquisition Imaging Spectrograph (RAISE) is a next-generation high resolution imaging spectrograph scheduled to fly on a NASA sounding rocket in 2006 to study the dynamics of the solar chromosphere and corona on time scales as short as 100 ms. High speed imaging from TRACE has shown that rapid motions and reconnection are central to the physics of the transition region and corona, but cannot resolve the differences between propagating phenomena and bulk motion. SoHO/CDS and SoHO/SUMER have yielded intriguing measurements of motion and heating in the solar atmosphere, and Solar-B/EIS will capture EUV spectra of flares in progress; but no currently planned instrument can capture spectral information in the chromosphere, transition region, or cool corona on the ∼ 1-10 Hz time scale required for few-second cadence spectral imaging or rapid wave motion studies. RAISE is uniquely suited to exploring this hard-to-reach domain.

This work is supported by NASA Grant NNG04WC01G to the Southwest Research Institute. Title: Clustering of the Small-Scale Field Authors: DeForest, C. E.; Lamb, D. A. Bibcode: 2004AAS...204.2008D Altcode: 2004BAAS...36..687D The face of the Sun is covered by small ephemeral magnetic regions that form, interact, and disappear on spatial scales of a few megameters and time scales of a few hours. By examining the history of each ephemeral region, it is possible to make inferences about the nature of the small-scale dynamo. We have examined timeseries of MDI magnetic data with a sensitive tracking code. We are able to resolve discrepancies in the size distribution of flux elements as determined by two other tracking efforts (those of Hagenaar and of Parnell). We find that only a small percentage of ephemeral regions actually emerge intact: the dominant process on small scales is asymmetric coalescence, suggesting that supergranular scale dynamo action plays only a minor role in the creation and maintenance of the network. We also report on a first-order clustering analysis of ephemeral regions, and discuss its implications for the origin of the ``magnetic carpet''. Title: A Soliton Solution for the Solar Corona: ``EIT Waves'' Explained Authors: Wills-Davey, M. J.; DeForest, C. E.; Stenflo, J. O. Bibcode: 2004AAS...204.2901W Altcode: 2004BAAS...36..695W Many aspects of ``EIT wave'' observations have proved incongruous with linear, plane-wave solutions. We find that solitons, rather than plane waves, produce a viable non-linear MHD solution for a single-pulse coronal compression wave. Aspects of the soliton solution describe properties of EIT waves, in particular: \begin{itemize}

coherence and integrity over large distances,

propagation velocities that can be substantially slower than expected Alfvén or fast-mode speeds, and

displacements that can potentially instigate loop oscillations. Additionally, this solution's very non-linearity may explain why EIT waves are so strongly correlated with coronal mass ejections. This research was funded by a grant from NASA. Title: Magnetic Element Tracking and Clustering Analysis Authors: Lamb, D. A.; DeForest, C. E. Bibcode: 2004AAS...204.3710L Altcode: 2004BAAS...36R.710L We have developed flux concentration tracking software to track and identify flux concentration behavior and origin events in photospheric magnetogram sequences. The tracking software is switchable to test and compare the behavior of two existing tracking codes, those of Hagenaar et al. (1999) and Parnell (2002). We present initial results from the use of the software on a deep-field sequence of MDI magnetograms. In particular, the two tracking methods yield significantly different distributions of flux concentration sizes. Furthermore, based on the ratio of coherent and incoherent origin of magnetic flux concentrations in a sequence of deep-field MDI magnetograms, it appears that ephemeral regions are not typically formed by emergence but rather by random coalescence of groups of smaller, unresolved flux concentrations. Hence, the size distribution of the solar network magnetic field may not be determined by the scale of the small-scale dynamo but rather by the clustering statistics of magnetic field elements in the surface flow field. We present a preliminary analysis and discuss the implications of flux emergence clustering in the quiet sun. Title: On Re-sampling of Solar Images Authors: DeForest, C. E. Bibcode: 2004SoPh..219....3D Altcode: Digital image data are now commonly used throughout the field of solar physics. Many steps of image data analysis, including image co-alignment, perspective reprojection of the solar surface, and compensation for solar rotation, require re-sampling original telescope image data under a distorting coordinate transformation. The most common image re-sampling methods introduce significant, unnecessary flaws into the data. More correct techniques have been known in the computer graphics community for some time but remain little known within the solar community and hence deserve further presentation. Furthermore, image distortion under specialized coordinate transformations is a powerful analysis technique with applications well beyond image resizing and perspective compensation. Here I give a brief overview of the mathematics of data re-sampling under arbitrary distortions, present a simple algorithm for optimized re-sampling, give some examples of distortion as an analysis tool, and introduce scientific image distortion software that is freely available over the Internet. Title: Future Observations with the Rapid Acquisition Imaging Spectrograph (RAISE) Authors: Hassler, D. M.; Deforest, C. E.; Slater, D.; Ayres, T.; Mason, H.; McIntosh, S.; Thomas, R. Bibcode: 2004cosp...35.2280H Altcode: 2004cosp.meet.2280H The Rapid Acquisition Imaging Spectrograph (RAISE) is a next-generation high resolution imaging spectrograph scheduled to fly on a NASA sounding rocket in 2006 to study the dynamics of the solar chromosphere and corona on time scales as short as 100 ms. High speed imaging from TRACE has shown that rapid motions and reconnection are central to the physics of the transition region and corona, but cannot resolve the differences between propagating phenomena and bulk motion. SoHO/CDS and SoHO/SUMER have yielded intriguing measurements of motion and heating in the solar atmosphere, and Solar-B/EIS will capture EUV spectra of flares in progress; but no currently planned instrument can capture spectral information in the chromosphere, transition region, or cool corona on the ~1-10 Hz time scale required for few-second cadence spectral imaging or rapid wave motion studies. RAISE is uniquely suited to exploring this hard-to-reach domain. Title: Magnetic Element Tracking and the Small-Scale Solar Dynamo Authors: Lamb, D.; Deforest, C. E. Bibcode: 2003AGUFMSH42B0530L Altcode: We have developed flux concentration tracking software to track and identify flux concentration behavior and origin events in photospheric magnetogram sequences. The tracking software is switchable to test and compare the behavior of two existing tracking codes, those of Hagenaar et al. (1999) and Parnell (2002). We present initial results from the use of the software on a deep-field sequence of MDI magnetograms. In particular, the two tracking methods yield significantly different distributions of flux concentration sizes. Furthermore, based on the ratio of coherent and incoherent origin of magnetic flux concentrations in a sequence of deep-field MDI magnetograms, we conclude that ephemeral regions are not typically formed by emergence but rather by random coalescence of groups of smaller, unresolved flux concentrations. Hence, the size distribution of the solar network magnetic field is not determined by the scale of the small-scale dynamo but rather by the clustering statistics of magnetic field elements in the surface flow field. Title: Stereoscopic Spectrosopy for Magnetic Field Measurements Authors: Deforest, C. E.; Hassler, D. M. Bibcode: 2003AGUFMSH41D..07D Altcode: We present a novel, photon-efficient technique for measuring the Zeeman splitting of a spectral line everywhere in an image plane. The technique, differential stereoscopy}, allows extraction of spectral line profiles from multiple dispersed, slitless ``smearogram'' images of the Sun such as are formed by a slitless, multi-order (``stereoscopic'') spectrograph. Because stereoscopic spectrographs admit all photons of interest, they can be over an order of magnitude more photon-efficient than traditional techniques. We will discuss the technique in the context of chromospheric and coronal magnetic fields, and present results from an initial proof-of-concept photospheric test using the ASP at the National Solar Observatory. Title: Results from the SwRI/LASP MXUVI Sounding Rocket Experiment (Feb. 8, 2002) Authors: Hassler, D. M.; DeForest, C. E.; Slater, D. C.; Woods, T. N. Bibcode: 2003SPD....34.2010H Altcode: 2003BAAS...35..845H We present results of the Multiple XUV Imager (MXUVI) experiment from the February 8, 2002 LASP sounding rocket flight (NASA Flight 36.192, Tom Woods, PI). The MXUVI experiment had the dual purpose of providing inter-calibration for the SOHO/EIT and TRACE instruments and providing a constraint on the coronal helium abundance by direct comparison of the coronal Ly-alpha lines of He II (304 angstroms) and H I (1216 angstroms). The MXUVI provided full-disk solar images of Fe IX/X 171 and H I Ly-alpha 1216 for inter-calibration with the SOHO/EIT and TRACE instruments, respectively, as well as off-limb observations of the He II 304 and H I 1216 angstrom lines to provide a constraint on the coronal helium abundance.

This work has been funded in part by NASA under grant NAG5-5140 to Southwest Research Institute. Title: A High Frequency Wave Search using TRACE Authors: De Forest, C. E.; De Pontieu, B. D.; Hassler, D. M. Bibcode: 2003SPD....34.0111D Altcode: 2003BAAS...35..807D We report on a possible detection of 100-milliHz band fast-mode waves in the solar chromosphere, seen with TRACE. Near the end of 2002, TRACE collected extremely high cadence images in the 1600 Å continuum; initial studies show a possible signature of waves propagating near the coronal Alfveń speed with periods as low as 10 seconds. Waves at this frequency are near the high frequency limit because the period is only 10-100 times the ion-electron collision time. We present these initial results and the outcome of an ongoing follow-on study. Title: EUV Solar Spectroscopic Explorer (ESSEX): Mission Concept for a Next Generation Imaging Spectrograph Authors: Hassler, Donald M.; DeForest, Craig E.; Slater, David C. Bibcode: 2003SPIE.4853...71H Altcode: We discuss a mission concept (ESSEX) for probing energy and mass transport in the solar atmosphere. The primary instrument on ESSEX is a high-speed EUV imaging spectrograph designed to extract plasma diagnostics from the small-scale, rapidly varying events that are thought to heat the solar atmosphere. We argue that spectral resolution is required to determine the physics that underlies the spectacular solar coronal images returned by TRACE and other EUV imaging telescopes. Previous and current spectrographs are severely limited in time resolution, and we present two rapid imaging spectrograph designs that are optimized for different tasks: the ESSEX spectrograph, intended as a pure science instrument to identify the physical mechanisms of energy and mass transport in generic solar features; and a synoptic spectrograph, intended as an operational instrument to quantify momentum and energy release in coronal mass ejections and filament liftoff events. If flown, ESSEX will provide high cadence observations required to trace the flow of energy through reconnection and wave motion in the solar atmosphere. It will achieve sub-arcsecond resolution in the transition region and corona with both spectroscopy and imaging over a continuous temperature range from 10,000 K to 10 million K, and will sample chromospheric wave motion at frequencies over 100 Hz. Title: Stereoscopic Spectroscopy: A New Technique for Rapid Magnetography Authors: Deforest, C. E. Bibcode: 2003ASPC..307...75D Altcode: No abstract at ADS Title: Book Review: Storms from the sun; the emerging science of space weather / Joseph Henry Press, Washington, D.C., 256 pp., 2002, ISBN 0-3090-7642-0. Authors: DeForest, Craig Bibcode: 2002Ast....30l..92D Altcode: No abstract at ADS Title: Book Review: The Cambridge Encyclopedia of the Sun / Cambridge University Press, New York, 256 pp., 2001, ISBN 0-521-78093-4. Authors: DeForest, Craig Bibcode: 2002Ast....30c..89D Altcode: No abstract at ADS Title: Book Review: Storms from the sun : the emerging science of space weather / Joseph Henry Press, 2002 Authors: Deforest, Craig Bibcode: 2002Ast....30...92D Altcode: No abstract at ADS Title: Book Review: Extreme stars: at the edge of creation / Cambridge University Press, New York, 236 pp., 2001, ISBN 0-521-40262-X. Authors: DeForest, Craig Bibcode: 2002Ast....30a..98D Altcode: No abstract at ADS Title: Relationships between CME's and prominences Authors: Schmieder, B.; van Driel-Gesztelyi, L.; Aulanier, G.; Démoulin, P.; Thompson, B.; De Forest, C.; Wiik, J. E.; Saint Cyr, C.; Vial, J. C. Bibcode: 2002AdSpR..29.1451S Altcode: We have studied the erupting prominences which were associated with coronal mass ejections during a series of campaigns involving both spacecraft and ground-based observatories. The evolution of the physical conditions within the prominences was established from Hα and magnetic field observations. Particular attention ahs been paid to the presence of mixed amgnetic polarity in the filament channel, the evolution of the shear of the large-scale magnetic field, and the existence of multiple magnetic inversion lines. We conclude that reconnection of large-scale coronal magnetic fields is responsible for both the CME and filament eruption. Title: Solar Polar Plume Lifetime and Coronal Hole Expansion: Determination from Long-Term Observations Authors: DeForest, C. E.; Lamy, P. L.; Llebaria, A. Bibcode: 2001ApJ...560..490D Altcode: We have generated off-limb polar synoptic charts of polar plume evolution at various solar altitudes using EUV Imaging Telescope and Large Angle and Spectrometric Coronagraph data from 1996 December. The charts allow direct measurement of the altitude expansion of the solar minimum coronal holes. We find expansion values that are consistent with the conventional picture of superradial expansion and inconsistent with radial expansion. Using visible red line data as a bridge between EUV and white-light images of the corona, we are able to confirm that the coronal structure seen at the base of the corona is preserved throughout the considered altitude range of 1.1-3.0 Rsolar. We show that polar plumes are episodic in nature, lasting perhaps 24 hr but recurring for up to weeks at a time; this strengthens the picture that they are caused by magnetic heating under the influence of supergranulation. Title: Book Review: The 23rd cycle: learning to live with a stormy star / Columbia University Press, New York, 207 pp., 2001, ISBN 0-231-12078-8. Authors: DeForest, Craig Bibcode: 2001Ast....29h..84D Altcode: No abstract at ADS Title: Fluxon Modeling of Force Free Magnetic Fields: Voronoi Method Authors: DeForest, C. E.; Kankelborg, C. C.; Longcope, D. W. Bibcode: 2001AGUSM..SH41A18D Altcode: We present a promising new form of quasi-Lagrangian magnetic model for the corona, a ``fluxon model''. Fluxons are discrete representations of field lines. Fluxon-based models are similar to traditional Lagrangian field models in that they have no numerical resistivity because field topology is explicitly preserved. They differ from traditional Lagrangian models in two ways: there is no fixed set of proximity relationships between the discrete elements of the model, preventing numerial runaway in evolving systems; and div B is explicitly maintained at 0. In a force-free field, the magnetic pressure and tension forces are in equilibrium. The fluxon formulation reduces determination of the field to a relaxation process. Calculation of the magnetic pressure and tension forces at each step in the relaxation is reduced to a variant of known, solved problems in computational geometry. In this presentation, we demonstrate a computationally efficient method of calculating these forces, using an approximation to the ``Voronoi foam'' of spatial neighborhoods defined by a particular collection of fluxons. Magnetic field modeling with fluxons offers several advantages: (1) it facilitates detailed investigation of field topology; (2) reconnection is completely controllable, because there is no numerical resistivity; (4) the modeled structures may be critically sampled, raising the prospect of unprecedented computational efficiency. These advantages together will ultimately allow explicit modeling of stability and reconnection in complex, slowly evolving coronal features such as polar plumes, prominences, and active regions. Title: Simultaneous Magnetographic and XUV Observations of a Coronal Jet Authors: McKenzie, D. E.; DeForest, C. Bibcode: 2001AGUSM..SH41A14M Altcode: On 03 November 2000, a jet of hot plasma appeared in the solar corona, and was observed by the Yohkoh Soft X-ray Telescope (SXT) and the TRACE coronal imager. The jet of magnetically channeled plasma, measuring over 280 megameters in length, serendipitously occurred within the high-resolution field of view of the SOHO Michelson Doppler Interferometer (MDI). We present the X-ray, extreme ultraviolet, and magnetographic observations, and attempt to draw conclusions about the evolution of the jet based upon the evolution of the magnetic field. Title: Lagrangian Modeling of Force Free Fields and Current Sheets: Fluxon representation and the Kernel Method Authors: Kankelborg, C. C.; Longcope, D. W.; DeForest, C. E. Bibcode: 2001AGUSM..SH41A17K Altcode: In force free magnetic fields, the magnetic pressure and tension forces are balanced. These forces may be represented in terms of arrangements of field lines (``fluxons''). We demonstrate a novel Lagrangian technique for modeling of force-free configurations in 2D and 3D with and without current sheets. The fundamental computational element in our model is the fluxon, a field-line-like entity that represents the configuration of a finite quantity of magnetic flux. The magnetic field in a volume is represented as a collection of fluxons, each with a geometry defined by a connected series of points. The magnetic curvature force is easily determined by finite differencing along a fluxon. A smoothing kernel is used to evaluate magnetic field strength and its gradient. By these means, the Lorentz force is determined. Relaxation to a force free state is accomplished by displacing the fluxons in the direction indicated by the Lorentz force. Further calculations with the smoothing kernel allow the evaluation of stored magnetic energy and mapping of current distributions in the volume. Magnetic field modeling in the fluxon representation offers several advantages: (1) it facilitates detailed investigation of field topology; (2) reconnection is completely controllable --- it cannot occur unless it is explicitly inserted into the model; (3) there is no numerical resistivity; (4) current sheets are critically sampled, raising the prospect of unprecedented computational efficiency. Title: Observation of Polar Plumes at High Solar Altitudes Authors: DeForest, C. E.; Plunkett, S. P.; Andrews, M. D. Bibcode: 2001ApJ...546..569D Altcode: Using the Large-Angle Spectrometric Coronagraph (LASCO) aboard the Solar and Heliospheric Observatory (SOHO) spacecraft, we have imaged polar plumes extending 30 Rsolar from disk center in the image plane and ~45 Rsolar in three-dimensional space, a factor of 2-3 farther than previous imaging measurements and well into the constant-velocity regime of wind flow. We find that the plumes maintain their overall linear morphology and density enhancement to at least this altitude range. Using LASCO photometry and a modeled cylindrical plume geometry, we derive the density excess within the plumes 30 Rsolar above the Sun (in three dimensions). At this altitude, the plumes are (2-4)×103 cm-3 above the background interplume density, with an estimated plasma β of order 300. The excess electron densities are a factor of 20-30 greater than the average total electron density estimates obtained from extrapolation of in situ measurements by Ulysses at 1 AU. The contrast between the high plume excess densities that we observe and the uniformity of the wind seen by Ulysses may best be explained by wind models that include horizontal mixing in the lower heliosphere between 45 Rsolar and Ulysses's altitude of ~200 Rsolar. Title: Solar Activity: The Earth Sun Connection near Solar Maximum Authors: DeForest, C. Bibcode: 2000AAS...197.2601D Altcode: 2000BAAS...32.1442D The Sun is currently in the maximum activity phase of its 11-year sunspot cycle, marking the reversal of its magnetic dipole moment and a peak in the number of sunspots, coronal mass ejections, and solar flares. Solar activity has long been known to affect the Earth and its geospace environment, but detailed understanding of the complex interaction between our star and its environment has remained elusive because solar and planetary data have been rich enough to identify events but not complete enough to constrain their physics. The unprecedented number and variety of spacecraft and ground based instruments that are observing the Sun, inner heliosphere, and Earth is at last providing data sets that can encompass the events of solar maximum from the detailed astrophysics of their origin, to their effects at Earth. The data are not only spectacular; they are also profoundly changing our understanding of the Sun's astrophysics and of its relevance to the Earth environment. Title: The origin and development of the May 1997 magnetic cloud Authors: Webb, D. F.; Lepping, R. P.; Burlaga, L. F.; DeForest, C. E.; Larson, D. E.; Martin, S. F.; Plunkett, S. P.; Rust, D. M. Bibcode: 2000JGR...10527251W Altcode: A complete halo coronal mass ejection (CME) was observed by the SOHO Large-Angle and Spectrometric Coronagraph (LASCO) coronagraphs on May 12, 1997. It was associated with activity near Sun center, implying that it was aimed earthward. Three days later on May 15 an interplanetary shock and magnetic cloud/flux rope transient was detected at the Wind spacecraft 190 RE upstream of Earth. The long enduring southward magnetic fields associated with these structures triggered a geomagnetic storm. The CME was associated with a small coronal arcade that formed over a filament eruption with expanding double ribbons in Hα emission. The flare was accompanied by a circular EUV wave, and the arcade was flanked by adjacent dimming regions. We surmise that these latter regions marked the feet of a flux rope that expanded earthward into the solar wind and was observed as the magnetic cloud at Wind. To test this hypothesis we determined key parameters of the solar structures on May 12 and compared them with the modeled flux rope parameters at Wind on May 15. The measurements are consistent with the flux rope originating in a large coronal structure linked to the erupting filament, with the opposite-polarity feet of the rope terminating in the depleted regions. However, bidirectional electron streaming was not observed within the cloud itself, suggesting that there is not always a good correspondence between such flows and ejecta. Title: Polar Plumes Authors: Deforest, C. Bibcode: 2000eaa..bookE2075D Altcode: Polar plumes (figure 1) are thin, bright, linear structures that are seen to emanate from the poles of the Sun during the `minimum' phase of the solar cycle, when there are well-developed polar CORONAL HOLES. They may be seen with the naked eye during a solar eclipse or at any time with coronagraph instruments sensitive to visible or ultraviolet light. When seen with visible light, they are often... Title: Solar Flares: Relation to Coronal Mass Ejections Authors: Deforest, C. Bibcode: 2000eaa..bookE2294D Altcode: SOLAR FLARES and SOLAR CORONAL MASS EJECTIONS have both been associated with geomagnetic activity such as the AURORA, radio interference and `geomagnetic storms' caused by large currents flowing through the Earth's magnetosphere. They are also both associated with high fluxes of energetic particles (`proton events') in near-Earth space. However, they are different types of event.... Title: Correction to “Change in photospheric magnetic flux during coronal mass ejections” Authors: Lara, Alejandro; Gopalswamy, Nat; DeForest, Craig Bibcode: 2000GeoRL..27.1863L Altcode: No abstract at ADS Title: Change in photospheric magnetic flux during coronal mass ejections Authors: Lara, Alejandro; Gopalswamy, Nat; DeForest, Craig Bibcode: 2000GeoRL..27.1435L Altcode: We report on the variations of photospheric magnetic flux during coronal mass ejections (CMEs). Using magneograms from the SOHO/MDI instrument, we have computed the magnetic flux of 7 active regions and one disappearing filament region associated with CMEs. When we plotted the flux versus time over a period of few days before, during and after the CME event, we found changes in the mean magnetic flux per pixel (∼4 arcsec²), ranging from ∼0.4 to ∼3.1 × 1017 Mx, in structures of size smaller than the active region. Flare onsets and the filament disappearance clearly occurred during periods of significant variations in the measured magnetic flux. Title: Magnetic Heating in Action: Life Cycles of Small Open Coronal Structures Authors: DeForest, C. E. Bibcode: 2000SPD....31.0202D Altcode: 2000BAAS...32..811D Magnetic reconnection and the accompanying release of energy are the prime candidate mechanism for coronal heating. Recent results (e.g. Hagenaar, Schrijver, and Title) from the SOHO/MDI instrument have shown that there is sufficient energy contained in the changing small-scale magnetic field to heat the corona. However, it is not at all clear that the continual reconnection of this ``magnetic carpet'' actually releases sufficient energy into the corona. Small, isolated, relatively long-lived structures such as coronal bright points and polar plumes are ideal places to search for the hypothetical energy deposition from the magnetic field into the quiet corona, because these structures are relatively isolated from the more complex surrounding corona. Polar plumes, in particular, require approximately continuous input of energy to exist and hence are good model structures for the quiet corona. High sensitivity 32-minute averaged around-the-clock sequences of magnetograms from MDI have recently become available, allowing the first detailed studies comparing the behavior of polar plumes with their footpoints' detailed evolution over the complete life cycle of several plumes. I will present data from joint TRACE/MDI and EIT/MDI studies relating plume genesis, life, and death to changes in the small scale magnetic configuration within the polar coronal holes. This work was funded through the SEC Guest Investigator program and via NASA grant NASG-5077. Title: Structure of a Large low-Latitude Coronal Hole Authors: Bromage, B. J. J.; Alexander, D.; Breen, A.; Clegg, J. R.; Del Zanna, G.; DeForest, C.; Dobrzycka, D.; Gopalswamy, N.; Thompson, B.; Browning, P. K. Bibcode: 2000SoPh..193..181B Altcode: Coronal holes on the Sun are the source of high-speed solar wind streams that produce magnetic disturbances at the Earth. A series of multi-wavelength, multi-instrument observations obtained during the 1996 `Whole Sun Month' campaign examined a large coronal hole in greater detail than ever before. It appeared on the Sun in August, and extended from the north pole to a large active region in the southern hemisphere. Its physical and magnetic structure and subsequent evolution are described. Title: In-Flight Determination of the Plate Scale of the Extreme-Ultraviolet Imaging Telescope Authors: Auchère, F.; DeForest, C. E.; Artzner, G. Bibcode: 2000ApJ...529L.115A Altcode: Using simultaneous observations of the Michelson Doppler Imager and Extreme-Ultraviolet Imaging Telescope (EIT) on board the Solar and Heliospheric Observatory spacecraft, we determined in flight the plate scale of the EIT. We found a value of 2.629"+/-0.001" pixel-1, in fair agreement with the 2.627"+/-0.001" pixel-1 value deduced from recent laboratory measurements of the focal length and much higher by 7 σ than the 2.622" pixel-1 value of the preflight calibrations. The plate scale is found to be constant across the field of view, confirming the negligible distortion level predicted by the theoretical models of the EIT. Furthermore, the 2 σ difference between our results and the latest laboratory measurements, although statistically small, may confirm a recent work suggesting that the solar photospheric radius may be 0.5 Mm lower than the classically adopted value of 695.99 Mm. Title: 3-D Magnetic Configurations for Filaments and Flares: The Role of ``Magnetic Dips'' and ``Bald Patches'' Authors: Aulanier, G.; Schmieder, B.; van Driel-Gesztelyi, L.; Kucera, T.; Démoulin, P.; Fang, C.; Mein, N.; Vial, J. -C.; Mein, P.; Tang, Y. H.; Deforest, C. Bibcode: 2000AdSpR..26..485A Altcode: The 3-D magnetic configuration of a filament and of a low energy flare is reconstructed, using linear mag- netohydrostatic (lmhs) extrapolations. In both cases, we find observational signatures of energy release at the locations of computed ``bald patches'' separatrices, characterised by field lines which are tangent to the photosphere.The filament was observed on Sept. 25, 1996, in Hα with the MSDP on the German VTT, Tenerife, as well as in Si IV with SOHO/SUMER. It is modeled as a twisted flux-tube deformed by the magnetic polarities observed with SOHO/MDI. The shape and location of the computed dipped field lines are in good agreement with the shape of the filament and its feet observed in Hα. Some ``bald patches'' (BPs) are present where the distribution of dips reaches the photosphere. We show that some of the large scale field lines rooted in BPs can be related to bright fine structures in Si IV. We propose that the plasma there is heated by ohmic dissipation from the currents expected to be present along the BP separatrices.The flare was observed on May 18, 1994, in soft X-rays with Yohkoh/SXT, and in Hα at Mitaka (Japan). The magnetic field is directly extrapolated from a photospheric magnetogram from Kitt Peak Observatory. The intersections with the photosphere of the computed separatrices match well the bright Hα ribbons. The later are associated to three BPs, with overlaying dipped field lines. We show that enhanced densities are present in these dips, which can be correlated with dark Hα fibrils.Both cases show the importance of dipped field lines and BPs in the solar atmosphere. Energy release via ohmic dissipation as well as reconnection along BP separatrices is proposed to provide heating observed as UV brightenings in filament channels and even as small flares Title: Comparisons of Interplanetary Scintillation and Optical Measurements of Solar Wind Acceleration with Model Results Authors: Breen, A. R.; de Forest, C. F.; Thompson, B. J.; McKenzie, J. F.; Modigliani, A.; Moran, P. J.; Williams, P. J. S. Bibcode: 2000AdSpR..26..781B Altcode: Observations of the fast, high latitude solar wind show that acceleration of the fast wind is complete by 10 solar radii (R), while measurements from the LASCO instrument on SOHO show that most of the acceleration takes place inside 5 R. A series of observations were made in September 1997 using EISCAT and the C2 and C3 coronagraphs aboard SOHO to measure the solar wind velocity profile from 3 R out to beyond 30 R. The overlapping fields of view of the instruments allowed direct comparisons to be made between IPS and optical estimations of flow velocity. Together, these measurements provide strong constraints on any model seeking to provide an explanation of the acceleration of the fast solar wind. We present the results of a comparison between out observations and the most recent version of the Lindau-Warsaw solar wind acceleration model Title: Numerical Simulations of Trapped Slow Magnetosonic Waves in Solar Coronal Plumes Authors: Ofman, L.; Deforest, C. E. Bibcode: 2000AdSpR..25.1909O Altcode: Recent observations of polar plumes in the southern solar coronal hole by the Extreme ultraviolet Imaging Telescope (EIT) on board the SOHO spacecraft show signatures of quasi-periodic compressional waves. Here, we present the results of a nonlinear, 2D MHD simulation of the slow magnetosonic waves in plumes for typical coronal conditions consistent with observations. Our numerical simulations confirm the interpretation of the observed intensity fluctuations as propagating slow magnetosonic waves. On March 7 1996 DeForest and Gurman (1998) detected quasi-periodic intensity variations of 10-20% in the EIT Fe IX and X line emission at 171A&ring that propagate outward in several polar plumes at 75-150 km s-1 with a period of 10-15 minutes. The observed propagation velocity agrees well with the expected sound velocity inside the plumes. The lower phase speed in the plumes than in the ambient plasma leads to partial trapping of the slow magnetosonic waves in the plumes. The slow magnetosonic waves may contribute to the heating of the lower corona by compressive dissipation Title: In Flight Determination of the Plate Scale of the EIT Authors: Auchere, F.; DeForest, C. E.; Artzner, G. Bibcode: 1999astro.ph.12213A Altcode: Using simultaneous observations of the MDI and EIT instruments on board the SoHO spacecraft, we determined in flight the plate scale of the EIT. We found a value of 2.629+-0.001 arc seconds per pixel, in fair agreement with the 2.627+-0.001 arc seconds per pixel value deduced from recent laboratory measurements of the focal length, and much higher by 7 sigma than the 2.622 arc seconds per pixel value of the pre-flight calibrations. The plate scale is found to be constant across the field of view, confirming the negligible distortion level predicted by the theoretical models of the EIT. Furthermore, the 2 sigma difference between our results and the latest laboratory measurements, although statistically small, may confirm a recent work suggesting that the solar photospheric radius may be 0.5 Mm lower than the classically adopted value of 695.99 Mm. Title: Long-Term Evolution Of Emissivity And Heating In A Solar Active Region Authors: van Driel-Gesztelyi, L.; Thompson, B.; Démoulin, P.; Orlando, S.; Bocchialini, K.; Oláh, K.; Kövári, Z.; Deforest, C.; Khan, J.; Fludra, A.; Mandrini, C. Bibcode: 1999ESASP.446..663V Altcode: 1999soho....8..663V We study the evolution of the heating and emissivity of an active region from its birth throughout its decay during six solar rotations (July-Nov. 1996). We analyse multi-wavelength and multi-instrument data obtained from SOHO (EIT, SUMER, CDS, MDI), Yohkoh (SXT), GOES and 10.7cm radio data from DRAO, Canada. We take one "snapshot" per rotation at the time of the central meridian passage (CMP) of the AR, outside of time of flares, which appears to be representative enough to allow us to make some general conclusions about the long-term evolution. Deriving physical parameters like intensity (flux), temperature and emission measure of the entire AR vs. time, we formulate mathematically the change in radiation emitted by the decaying AR at several wavelengths. Combining the emissivity data with the evolution of magnetic flux density as the flux is being dispersed by small- and larger-scale convective motions, we make an attempt to understand the physics behind the emission and heating. We also analyse the effects of flaring on the heating of the AR, and study whether and how the flare properties evolve during the life of the active region. Title: Polar Plumes Observed at Extreme Coronal Altitudes Authors: Deforest, C. E.; Plunkett, S. P. Bibcode: 1999AAS...19410801D Altcode: Polar plumes, unipolar high density structures in the polar coronal holes, are key to our understanding of solar wind acceleration and coronal heating. Because unipolar magnetic flux concentrations in the coronal hole account for approximately 50 leaves the coronal hole (DeForest et al., 1996), plumes (which arise from some such concentrations) are tracers of a type of magnetic structure that fills nearly half of the solar system at solar minimum. Plumes have been observed up to altitudes of about 10 solar radii with the LASCO instrument (DeForest et al., 1996), above which they fade into the coronal background. There is some contention (Habbal and Woo, 1997; Paetzold and Bird, 1998) over whether plumes extend into the interplanetary medium or become mixed with the interplume solar wind at altitudes between 10 and 100 solar radii. Several mechanisms, including the Kelvin-Helmholtz two-stream instability and cross-mode resonant wave scattering near the alfvenic point in the wind's acceleration, have been proposed that could break up the structure of the observed plumes. Using the LASCO C-3 instrument aboard SOHO (Brueckner et al, 1995) to accumulate multiple images that we then recombine, we have generated coronal images with effective exposure times in the thousands of seconds and actual durations of less than four hours. These images clearly show polar plumes extending to altitudes of 25 solar radii or more, very close to the outer edge of the C-3 field of view and above the likely alfvenic point of the wind flow. Title: Polar plumes observed at extreme coronal altitudes. Authors: Deforest, C. E.; Plunkett, S. P. Bibcode: 1999BAAS...31.1241D Altcode: No abstract at ADS Title: Magnetic Field Evolution and Topology of an AR Authors: Mandrini, C. H.; Deng, Y. Y.; Schmieder, B.; Démoulin, P.; Rudawy, P.; Nitta, N.; Newmark, J.; de Forest, C. Bibcode: 1999ASPC..184..276M Altcode: Active region 7968 was observed during runs of a coordinated SOHO, Yohkoh and ground-based observatory program (Joint Observing Program, JOP, 17). The region appeared and decayed in a seven day period (June 3 to 10, 1996). In this time, mainly during June 6, it presented a very dynamical behaviour. Flux emerged in between the two main polarities and Arch Filament Systems (AFS) were observed to be linked to this emergence. We analyze the evolution of some over dark arches observed during flux emergence, forming two systems of AFS. Modelling the magnetic field, we find that these systems were associated to field lines having dips tangent to the photosphere (the so called "bald patches", BPs). We discuss their evolution in terms of emergence of the dipped portion of the lines or of magnetic field reconnection. Title: Long-Term Magnetic Evolution of an AR and its CME Activity Authors: van Driel-Gesztelyi, L.; Mandrini, C. H.; Thompson, B.; Plunkett, S.; Aulanier, G.; Démoulin, P.; Schmieder, B.; de Forest, C. Bibcode: 1999ASPC..184..302V Altcode: Using SOHO/MDI full-disc magnetic maps, we follow the magnetic evolution of a solar active region for several months in the period of July-November 1996. We extrapolate the photospheric magnetic fields in the linear force-free approximation and match the modelled field lines with the soft X-ray loops observed with the Yohkoh/SXT in order to diagnose the coronal magnetic shear. We find that while the turbulent motions diffuse the flux, the differential rotation, and possibly twisted flux emergence, increase the magnetic shear. Flares are observed during the first three rotations, while CME events (observed by SOHO/EIT and LASCO) originate from this AR from its emergence throughout its decay. Several early CMEs, while none of the late CMEs, are related to flare events above the GOES B1 level. We find that the late CMEs occur when the magnetic shear, after accumulating for four rotations, reaches a high level and saturates. We propose that CME activity serves as a valve through which the AR could get rid of excess shear and helicity. Title: Is the chromosphere hotter in coronal holes? Authors: Gopalswamy, N.; Shibasaki, K.; Thompson, B. J.; Gurman, J. B.; Deforest, C. E. Bibcode: 1999AIPC..471..277G Altcode: 1999sowi.conf..277G Coronal holes are brighter than the quiet Sun in microwaves. Microwave emission from the quiet Sun is optically thick thermal bremsstrahlung from the upper chromosphere. Therefore, the optically thick layer in the coronal hole chromosphere must be hotter than the corresponding layer in the quiet chromosphere. We present microwave and SOHO observations in support of this idea. Because of the availability of simultaneous EUV and microwave images it is now possible to obtain more details of this enigmatic phenomenon. In this paper, we highlight the primary properties of the microwave enhancement in coronal holes and point out some related phenomena. Finally, we summarize the possible explanations of the radio enhancement. Title: Microwave enhancement and variability in the elephant's trunk coronal hole: Comparison with SOHO observations Authors: Gopalswamy, N.; Shibasaki, K.; Thompson, B. J.; Gurman, J.; DeForest, C. Bibcode: 1999JGR...104.9767G Altcode: We report on an investigation of the microwave enhancement and its variability in the elephant's trunk coronal hole observed during the Whole Sun Month campaign (August 10 to September 9, 1996). The microwave images from the Nobeyama radioheliograph were compared with magnetograms and EUV images obtained simultaneously by the Michelson Doppler imager and the extreme ultraviolet imaging telescope (EIT) on board the SOHO spacecraft. The combined data set allowed us to understand the detailed structure of the microwave enhancement in the spatial and temporal domains. We find that the radio enhancement is closely associated with the enhanced unipolar magnetic regions underlying the coronal hole. The radio enhancement consists of a smooth component originating from network cell interiors and a compact component associated with network magnetic elements. When a minority polarity is present near a majority polarity element, within the coronal hole, the resulting mixed polarity region is associated with a bright-point-like emission in coronal EUV lines such as the Fe XII 195 Å. These coronal bright points are also observed distinctly in the EIT 304 Å band, but not in microwaves. On the other hand, the lower-temperature line emission (304 Å) and the microwave enhancement are associated with the unipolar magnetic flux elements in the network. We found strong time variability of the radio enhancement over multiple timescales, consistent with the initial results obtained by SOHO instruments. The microwave enhancement is most probably due to temperature enhancement in the chromosphere and may be related to the origin of solar wind. Title: Temporal Evolution and Physical Properties of North Polar Coronal Hole from SPARTAN 201-05, SOHO, TRACE and Mk3 Authors: Guhathakurta, M.; Deforest, C.; Fisher, R. R.; Ofman, L.; Kucera, T.; Gibson, S.; Spartan201 Team Bibcode: 1999AAS...194.3203G Altcode: 1999BAAS...31..870G Polar coronal rays/plumes as long lived structures that extend out to 6 R_sun were first observed during the first flight of SPARTAN 201 spacecraft during April 11-12 of 1993. In this paper we will present detail observations from the WLC aboard Spartan 201 spacecraft (31 Oct.- 2 Nov.,1998) of the north polar coronal hole and comapre its physical properties to the past three Spartan missions. We will present comparisons of the Spartan WL observations with the Mk3 pB observations, SOHO LASCO and EIT observations, and finally the high resolution TRACE 171 Angstroms observations, to characterize the north polar coronal hole all the way from the base of the corona out to 30 R_sun. We will also look for signatures of waves (quasi-period variations) in the coronal hole plumes and interplume regions in the high cadence Spartan pB observations obtained during this mission. Title: Slow Magnetosonic Waves in Coronal Plumes Authors: Ofman, L.; Nakariakov, V. M.; DeForest, C. E. Bibcode: 1999ApJ...514..441O Altcode: Recent observations of polar plumes in the southern solar coronal hole by the Extreme-Ultraviolet Imaging Telescope (EIT) on board the SOHO spacecraft show signatures of quasi-periodic compressional waves with periods of 10-15 minutes. The relative wave amplitude was found to increase with height in the plumes up to about 1.2 Rsolar. Using a one-dimensional linear wave equation for the magnetosonic wave, we show that the waves are propagating and that their amplitude increases with height. The observed propagation velocity agrees well with the expected sound velocity inside the plumes. We present the results of the first nonlinear, two-dimensional, magnetohydrodynamic (MHD) simulation of the magnetosonic waves in plumes for typical coronal conditions consistent with observations and gravitationally stratified solar corona. We find numerically that outward-propagating slow magnetosonic waves are trapped, and nonlinearly steepen in the polar plumes. The nonlinear steepening of the magnetosonic waves may contribute significantly to the heating of the lower corona by compressive dissipation. Title: SOHO Observations of Density Fluctuations in Coronal Holes Authors: Ofman, L.; Romoli, M.; Noci, G.; Poletto, G.; Kohl, J. L.; Howard, R. A.; Cyr, C. St.; Deforest, C. E. Bibcode: 1999SSRv...87..287O Altcode: In recent UVCS/SOHO White Light Channel (WLC) observations we found quasi-periodic variations in the polarized brightness (pB) in the polar coronal holes at heliocentric distances of 1.9 to 2.45 solar radii. The motivation for the observation is the 2.5D MHD model of solar wind acceleration by nonlinear waves, that predicts compressive fluctuations in coronal holes. In February 1998 we performed new observations using the UVCS/WLC in the coronal hole and obtained additional data. The new data corroborate our earlier findings with higher statistical significance. The new longer observations show that the power spectrum peaks in the 10 12 minute range. These timescales agree with EIT observations of brightness fluctuations in polar plumes. We performed preliminary LASCO/C2 observations in an effort to further establish the coronal origin of the fluctuations. Title: The Solar Minimum Active Region 7978, Its X2.6/1B Flare, CME, and Interplanetary Shock Propagation of 9 July 1996 Authors: Dryer, M.; Andrews, M. D.; Aurass, H.; DeForest, C.; Galvin, A. B.; Garcia, H.; Ipavich, F. M.; Karlický, M.; Kiplinger, A.; Klassen, A.; Meisner, R.; Paswaters, S. E.; Smith, Z.; Tappin, S. J.; Thompson, B. J.; Watari, S. I.; Michels, D. J.; Brueckner, G. E.; Howard, R. A.; Koomen, M. J.; Lamy, P.; Mann, G.; Arzner, K.; Schwenn, R. Bibcode: 1998SoPh..181..159D Altcode: The first X-class flare in four years occurred on 9 July 1996. This X2.6/1B flare reached its maximum at 09:11 UT and was located in active region 7978 (S10° W30°) which was an old-cycle sunspot polarity group. We report the SOHO LASCO/EIT/MDI and SOONSPOT observations before and after this event together with Yohkoh SXT images of the flare, radio observations of the type II shock, and GOES disk-integrated soft X-ray flux during an extended period that included energy build-up in this active region. Title: 3-D magnetic configurations supporting prominences. II. The lateral feet as a perturbation of a twisted flux-tube Authors: Aulanier, G.; Demoulin, P.; van Driel-Gesztelyi, L.; Mein, P.; Deforest, C. Bibcode: 1998A&A...335..309A Altcode: In a previous paper we have shown that a twisted flux-tube is the most probable magnetic configuration supporting prominences. The model interprets many observations in a natural way (in particular the magnetic measurements in prominences and the chirality properties). Moreover, prominence feet appear as a direct consequence of the parasitic polarities present in the filament channel. Here we investigate further the link between feet and parasitic polarities by modelling explicitly these polarities. We show that the prominence lateral feet appear naturally, above secondary photospheric inversion lines and we describe the morphological change of feet as parasitic polarities evolve. This approach is applied to an observed filament in Hα with the MSDP on the German VTT (Tenerife) where SOHO/MDI magnetograms are available. We show that the shape of the prominence is defined by the distribution of the dips in the computed magnetic configuration. Then we analyse the topology of the magnetic field using the quasi-separatrix layers (QSLs) method. We describe the basic changes in the topology as the parasitic polarities evolve, in particular how the configuration pass from an OX to an OF topology. We find a correspondance between the computed QSLs and some of the chromospheric brightenings, observed around the feet of filaments in the y line (Ca II, 8542 Angstroms). It confirms the deduced magnetic configuration and shows that energy release is present at a low level in the complex topology of the filament configuration. Title: Observation of Quasi-periodic Compressive Waves in Solar Polar Plumes Authors: DeForest, C. E.; Gurman, J. B. Bibcode: 1998ApJ...501L.217D Altcode: On 1996 March 7, the Solar and Heliospheric Observatory spacecraft conducted a multi-instrument campaign to observe polar plumes in the south polar coronal hole. Recent time-domain analyses of EUV Imaging Telescope images from that campaign show filamentary substructure in the plumes, on a length scale of ~5", which changes on timescales of a few minutes, and coherent quasi-periodic perturbations in the brightness of Fe IX and Fe X line emission at 171 Å from the plumes. The perturbations amount to 10%-20% of the plumes' overall intensity and propagate outward at 75-150 km s-1, taking the form of wave trains with periods of 10-15 minutes and envelopes of several cycles. We conclude that the perturbations are compressive waves (such as sound waves or slow-mode magnetosonic waves) propagating along the plumes. Assuming that the waves are sonic yields a mechanical energy flux of 150-400 W m-2 (1.5-4 ×105 ergs cm-2 s-1) in the plumes. Title: Multiwavelength Observations of a Coronal Hole Authors: Gopalswamy, N.; Shibasaki, K.; Deforest, C. E.; Bromage, B. J. I.; Del Zanna, G. Bibcode: 1998ASPC..140..363G Altcode: 1998ssp..conf..363G No abstract at ADS Title: Evolution of the Magnetic Field and Chromospheric Fine Structure in a Filament Channel Authors: van Driel-Gesztelyi, L.; Mein, P.; Mein, N.; Schmieder, B.; Malherbe, J. -M.; Aulanier, G.; Démoulin, P.; Deforest, C.; Staiger, J. Bibcode: 1998ASPC..155..321V Altcode: 1998sasp.conf..321V No abstract at ADS Title: Non potentiality of coronal loops above active regions Authors: Aulanier, G.; Schmieder, B.; Démoulin, P.; van Driel-Gesztelyi, L.; Deforest, C. Bibcode: 1998ASPC..155..105A Altcode: 1998sasp.conf..105A No abstract at ADS Title: Filament Disparition Brusque and CME - September 25-26, 1996 Event Authors: van Driel-Gesztelyi, L.; Schmieder, B.; Aulanier, G.; Demoulin, P.; Martens, P. C. H.; Zarro, D.; Deforest, C.; Thompson, B.; St. Cyr, C.; Kucera, T.; Burkepile, J. T.; White, O. R.; Hanaoka, Y.; Nitta, N. Bibcode: 1998ASPC..150..366V Altcode: 1998IAUCo.167..366V; 1998npsp.conf..366V No abstract at ADS Title: 3-D Modelling of a Filament Observed in Hα and with SOHO Authors: Aulanier, G.; Schmieder, B.; Démoulin, P.; Mein, N.; van Driel-Gesztelyi, L.; Mein, P.; Vial, J. C.; Deforest, C. Bibcode: 1998ESASP.417..217A Altcode: 1998cesh.conf..217A No abstract at ADS Title: New Images of the Solar Corona Authors: Gurman, Joseph B.; Thompson, Barbara J.; Newmark, Jeffrey A.; Deforest, Craig E. Bibcode: 1998ASPC..154..329G Altcode: 1998csss...10..329G In 1.5 years of operation, The Extreme Ultraviolet Imaging Telescope (EIT) on SOHO has obtained over 40,000 images of the Sun in four wavebands between 171 Angstroms and 304 Angstroms, with spatial resolution limited only by the pixel scale of 2.59 arcsec. These images, and in particular compilations of time series of images into digital movies, have changed several of our ideas about the corona at temperatures of 0.9 - 2.5 MK. For the first time, we are able to see outflow in polar plumes and microjets inputting momentum into the high-speed, polar wind flow. For the first time, in conjunction with the LASCO coronagraphs and ground-based He I imagers, we have been able to see all the structures involved in coronal mass ejections (CMEs), from the surface of the Sun to 30 solar radii above it. In several cases, we have been able to observe directly the dramatic Moreton waves emanating from the active region where the CMEs originate, and radiating across virtually the entire visible hemisphere of the Sun. We interpret these large-scale coronal disturbances as fast-mode waves. Such events appear in the SOHO-LASCO coronagraphs as earthward-directed, and several have been detected by solar wind monitoring experiments on SOHO and other spacecraft. We have been able to view a variety of small-scale phenomena as well, including motions in prominences and filaments, macrospicular and polar microjet eruptions, and fine structures in the polar crown filament belt. The multi-wavelength capability of EIT makes it possible to determine the temperature of the coronal plasma and, here, too, we have been afforded a novel view: the heating in coronal active regions occurs over a considerably larger area than the high-density loops structures alone (i.e., bright features) would indicate. Title: 3-D Modelling of a Filament Observed in Hα and with SOHO/MDI Authors: Aulanier, G.; Démoulin, P.; van Driel-Gesztelyi, L.; Mein, P.; Deforest, C. Bibcode: 1998ASPC..155..326A Altcode: 1998sasp.conf..326A No abstract at ADS Title: Polar plume dynamics: an observational overview Authors: Deforest, C. Bibcode: 1998ESASP.421...63D Altcode: 1998sjcp.conf...63D No abstract at ADS Title: Magnetic Flux in Modeled Magnetic Clouds at 1 AU and Some Specific Comparisons to Associated Photospheric Flux Authors: Lepping, R. P.; Szabo, A.; DeForest, C. E.; Thompson, B. J. Bibcode: 1997ESASP.415..163L Altcode: 1997cpsh.conf..163L No abstract at ADS Title: The Structure and Evolution of Solar Coronal Holes Observed by SOHO During August and September 1996 Authors: Bromage, B. J. I.; del Zanna, G.; Fludra, A.; DeForest, C.; Thompson, B. Bibcode: 1997ESASP.415..307B Altcode: 1997cpsh.conf..307B No abstract at ADS Title: Polar Plume Anatomy: Results of a Coordinated Observation Authors: DeForest, C. E.; Hoeksema, J. T.; Gurman, J. B.; Thompson, B. J.; Plunkett, S. P.; Howard, R.; Harrison, R. C.; Hasslerz, D. M. Bibcode: 1997SoPh..175..393D Altcode: On 7 and 8 March 1996, the SOHO spacecraft and several other space- and ground-based observatories cooperated in the most comprehensive observation to date of solar polar plumes. Based on simultaneous data from five instruments, we describe the morphology of the plumes observed over the south pole of the Sun during the SOHO observing campaign. Individual plumes have been characterized from the photosphere to approximately 15 R⊙ yielding a coherent portrait of the features for more quantitative future studies. The observed plumes arise from small (∼ 2-5 arc sec diameter) quiescent, unipolar magnetic flux concentrations, on chromospheric network cell boundaries. They are denser and cooler than the surrounding coronal hole through which they extend, and are seen clearly in both Feix and Fexii emission lines, indicating an ionization temperature between 1.0-1.5 x 106 K. The plumes initially expand rapidly with altitude, to a diameter of 20-30 Mm about 30 Mm off the surface. Above 1.2 R⊙ plumes are observed in white light (as `coronal rays') and extend to above 12 R⊙. They grow superradially throughout their observed height, increasing their subtended solid angle (relative to disk center) by a factor of ∼10 between 1.05 R⊙ and 4-5 R⊙ and by a total factor of 20-40 between 1.05 R⊙ and 12 R⊙. On spatial scales larger than 10 arc sec, plume structure in the lower corona (R < 1.3 R⊙) is observed to be steady-state for periods of at least 24 hours; however, on spatial scales smaller than 10 arc sec, plume XUV intensities vary by 10-20% (after background subtraction) on a time scale of a few minutes. Title: Time Variability of Polar Plumes as observed with SoHO/EIT and SoHO/MDI Authors: Deforest, C. E.; Gurman, J. B.; Moses, J. D. Bibcode: 1997SPD....28.0803D Altcode: 1997BAAS...29..912D Polar plumes are magnetically open high density structures that are observed in the polar coronal holes. They arise from unipolar magnetic footpoints in between chromospheric network cells, and expand as they rise through the corona to altitudes of at least 15-20 solar radii. On timescales of hours, plumes are remarkably stable, quiescent structures; however, we find that plumes vary significantly in XUV intensity on time scales of a few minutes and length scales of about an arc minute, based on high cadence observations in the EIT 171A and 195A passbands. The observed variations propagate outward with speeds of about 300 km/sec. We demonstrate this effect in several plumes observed during different EIT high cadence pole observations; compare observed variations in the photospheric field, as measured simultaneously by MDI, to the intensity variations in the plumes; and suggest whether the outward motions represent physical structures or wave motion. Title: Initial Comparison of MDI Photospheric Magnetic Movies and CDS Transition Region Movies in Quiet Sun Authors: Tarbell, T.; Brekke, P.; Fludra, A.; Deforest, C.; Saba, J.; Covington, J. Bibcode: 1997SPD....28.0111T Altcode: 1997BAAS...29..881T We present simultaneous, coaligned movies of photospheric magnetic fields and transition region (TR) intensities in very quiet sun near disk center obtained by SOHO in January, 1997. For example, the 22 Jan 1997 CDS movies show He I 584 (2x10(4) K) and O V 630 (2.4 x 10(5) K) from 16:51 to 19:54 UT, with a 310 x 240 arcsecond field of view, 105 second cadence, and 1.7 arcsecond pixels. MDI photospheric longitudinal magnetograms, with 60 second cadence and 0.6 arcsecond pixels, have been coaligned with these. Bright TR emission correlates more strongly with close bipoles in the photospheric magnetic field than with magnetic flux alone. Some strong photospheric flux tubes are barely visible in the TR emission, appearing only occasionally in connections with nearby weak opposite polarity fields. Bright transient emissions in the TR are located at places of cancelling opposite polarities in photospheric magnetic fields. The flux cancellation continues for tens of minutes or hours in the magnetic movies. Searches for more rapid magnetic counterparts to these TR transients and for emerging magnetic flux regions in the movies are under way. This work was supported by NASA grant NAG5-3077 at Stanford and Lockheed Martin. Title: Structure and Rotation of the Solar Interior: Initial Results from the MDI Medium-L Program Authors: Kosovichev, A. G.; Schou, J.; Scherrer, P. H.; Bogart, R. S.; Bush, R. I.; Hoeksema, J. T.; Aloise, J.; Bacon, L.; Burnette, A.; de Forest, C.; Giles, P. M.; Leibrand, K.; Nigam, R.; Rubin, M.; Scott, K.; Williams, S. D.; Basu, Sarbani; Christensen-Dalsgaard, J.; Dappen, W.; Rhodes, E. J., Jr.; Duvall, T. L., Jr.; Howe, R.; Thompson, M. J.; Gough, D. O.; Sekii, T.; Toomre, J.; Tarbell, T. D.; Title, A. M.; Mathur, D.; Morrison, M.; Saba, J. L. R.; Wolfson, C. J.; Zayer, I.; Milford, P. N. Bibcode: 1997SoPh..170...43K Altcode: The medium-l program of the Michelson Doppler Imager instrument on board SOHO provides continuous observations of oscillation modes of angular degree, l, from 0 to ∽ 300. The data for the program are partly processed on board because only about 3% of MDI observations can be transmitted continuously to the ground. The on-board data processing, the main component of which is Gaussian-weighted binning, has been optimized to reduce the negative influence of spatial aliasing of the high-degree oscillation modes. The data processing is completed in a data analysis pipeline at the SOI Stanford Support Center to determine the mean multiplet frequencies and splitting coefficients. The initial results show that the noise in the medium-l oscillation power spectrum is substantially lower than in ground-based measurements. This enables us to detect lower amplitude modes and, thus, to extend the range of measured mode frequencies. This is important for inferring the Sun's internal structure and rotation. The MDI observations also reveal the asymmetry of oscillation spectral lines. The line asymmetries agree with the theory of mode excitation by acoustic sources localized in the upper convective boundary layer. The sound-speed profile inferred from the mean frequencies gives evidence for a sharp variation at the edge of the energy-generating core. The results also confirm the previous finding by the GONG (Gough et al., 1996) that, in a thin layer just beneath the convection zone, helium appears to be less abundant than predicted by theory. Inverting the multiplet frequency splittings from MDI, we detect significant rotational shear in this thin layer. This layer is likely to be the place where the solar dynamo operates. In order to understand how the Sun works, it is extremely important to observe the evolution of this transition layer throughout the 11-year activity cycle. Title: The Solar Minimum X2. 6/1B Flare and CME of 9 July 1996; Part 1: Solar Data Authors: Andrews, M. D.; Dryer, M.; Aurass, H.; DeForest, C.; Kiplinger, A. L.; Meisner, R.; Paswaters, S. E.; Smith, Z.; Tappipn, S. J.; Thompson, B. J.; Watari, S. I.; Lamy, P.; Mann, G.; Schwenn, R.; Michels, D. J.; Brueckner, G. E.; Howard, R. A.; Koomen, M. Bibcode: 1997ESASP.404..169A Altcode: 1997cswn.conf..169A No abstract at ADS Title: Quasi-Periodic Compressive Waves in Polar Plumes Authors: Deforest, C. E.; Gurman, J. B. Bibcode: 1997ESASP.404..775D Altcode: 1997cswn.conf..775D No abstract at ADS Title: Solar Magnetic Field Events related to CMEs observed with SOHO (MDI, EIT, SUMER, LASCO) Authors: Schmieder, B.; van Driel-Gesztelyi, L.; Wiik, J. E.; Thompson, B.; de Forest, C.; Saint Cyr, C.; Vial, J. -C.; Nitta, N.; Simnett, G. Bibcode: 1997IAUJD..19E..42S Altcode: We shall present two CMEs observed by LASCO during the minimum of activity of the Sun. These are associated with filament disparitions brusques (DB). CME and DB definitively seem to be consequences of global magnetic field instability, which causes reconnection of pre-existing field lines in the corona. We shall demonstrate how cancelling flux and converging magnetic field in photosphere may destabilize coronal streamers overlying one or two filament channels. Title: The Solar Minimum X2. 6/1B Flare and CME of 9 July 1996; Part 2: Propagation Authors: Dryer, M.; Andrews, M. D.; Aurass, H.; DeForest, C.; Karlicky, M.; Kiplinger, A.; Klassen, A.; Meisner, R.; Ipavich, F. M.; Galvin, A. B.; Paswaters, S. E.; Smith, Z.; Tappin, S. J.; Thompson, B. J.; Watari, S. -I.; Michels, D. J.; Brueckner, G. E.; Howard, R. A.; Koomen, M. J.; Lamy, P.; Mann, G.; Arzner, K.; Schwenn, R. Bibcode: 1997ESASP.404..331D Altcode: 1997cswn.conf..331D No abstract at ADS Title: Internal structure and rotation of the Sun: First results from MDI data Authors: Kosovichev, A. G.; Schou, J.; Scherrer, P. H.; Bogart, R. S.; Bush, R. I.; Hoeksema, J. T.; Aloise, J.; Bacon, L.; Burnette, A.; De Forest, C.; Giles, P. M.; Leibrand, K.; Nigam, R.; Rubin, M.; Scott, K.; Williams, S. D.; Basu, Sarbani; Christensen-Dalsgaard, J.; Däppen, W.; Rhodes, E. J., Jr.; Duvall, T. L., Jr.; Howe, R.; Thompson, M. J.; Gough, D. O.; Sekii, T.; Toomre, J.; Tarbell, T. D.; Title, A. M.; Mathur, D.; Morrison, M.; Saba, J. L. R.; Wolfson, C. J.; Zayer, I.; Milford, P. N. Bibcode: 1997IAUS..181..203K Altcode: No abstract at ADS Title: Prominence Activity Related to CME Observed by SOHO, YOHKOH and Ground-Based Observatories Authors: Schmieder, B.; van Driel-Gesztelyi, L.; Wiik, J. E.; Kucera, T.; Thompson, B.; de Forest, C.; Saint Cyr, C.; Simnett, G. M. Bibcode: 1997ESASP.404..663S Altcode: 1997cswn.conf..663S No abstract at ADS Title: Time-Distance Helioseismology with the MDI Instrument: Initial Results Authors: Duvall, T. L., Jr.; Kosovichev, A. G.; Scherrer, P. H.; Bogart, R. S.; Bush, R. I.; de Forest, C.; Hoeksema, J. T.; Schou, J.; Saba, J. L. R.; Tarbell, T. D.; Title, A. M.; Wolfson, C. J.; Milford, P. N. Bibcode: 1997SoPh..170...63D Altcode: In time-distance helioseismology, the travel time of acoustic waves is measured between various points on the solar surface. To some approximation, the waves can be considered to follow ray paths that depend only on a mean solar model, with the curvature of the ray paths being caused by the increasing sound speed with depth below the surface. The travel time is affected by various inhomogeneities along the ray path, including flows, temperature inhomogeneities, and magnetic fields. By measuring a large number of times between different locations and using an inversion method, it is possible to construct 3-dimensional maps of the subsurface inhomogeneities. The SOI/MDI experiment on SOHO has several unique capabilities for time-distance helioseismology. The great stability of the images observed without benefit of an intervening atmosphere is quite striking. It has made it possible for us to detect the travel time for separations of points as small as 2.4 Mm in the high-resolution mode of MDI (0.6 arc sec pixel-1). This has enabled the detection of the supergranulation flow. Coupled with the inversion technique, we can now study the 3-dimensional evolution of the flows near the solar surface. Title: An Equatorial Coronal Hole at Solar Minimum Authors: Bromage, B. J. I.; Del Zanna, G.; DeForest, C.; Thompson, B.; Clegg, J. R. Bibcode: 1997ESASP.404..241B Altcode: 1997cswn.conf..241B No abstract at ADS Title: Coordinated SOHO Observations of Polar Plumes Authors: Deforest, C. E.; Scherrer, P. H.; Tarbell, T.; Harrison, R. A.; Fludra, A.; Delaboudiniere, J. P.; Gurman, J. B.; Wilhelm, K.; Lemaire, P.; Hassler, D. M.; Kohl, J. L.; Noci, G.; Fineschi, S.; Brueckner, G. E.; Howard, R. A.; Cyr, O. C. St. Bibcode: 1996AAS...188.4909D Altcode: 1996BAAS...28R.898D On 7 and 8 March 1996, SOHO instruments engaged in their first joint science operation, a 12-hr observation of polar plumes over the South polar coronal hole. The observing mini-campaign included observations from SOHO, other spacecraft, and ground-based observatories. Contributing SOHO instruments -- in order of altitude, MDI, CDS, SUMER, EIT, UVCS, and LASCO -- made overlapping, simultaneous observations of plume structures from the photosphere out to the LASCO C3 limit of 32 solar radii. MDI provided line-of-sight surface magnetograms with a one-min cadence and 0.6 arcsec resolution; CDS, SUMER, and EIT supplied temperature-sensitive images of the lower corona with varying cadences and resolutions; UVCS measured fluctuations in Ly B intensity across the coronal hole with a one-min cadence at 1.4 R0; and LASCO imaged the entire corona out to 30 R0 in various visible passbands. Plume footpoints in the lower corona are observed by EIT and CDS to vary by a factor of two in EUV brightness with a timescale of tens of minutes, while the structures above are (as as been previously observed) quiescent on at least a ten-hr time scale. We present preliminary results of cross-instrument analysis of the observed plumes, and suggest how this and similar future data sets can be used to constrain quiet-sun wind acceleration and coronal heating models for the coronal hole. This research is supported by the SOI-MDI NASA contract NAG5-3077 at Stanford University. SOHO is project of international cooperation between NASA and ESA. Title: Initial Results from SOI/MDI High Resolution Magnetograms Authors: Title, A.; Tarbell, T.; Frank, Z.; Schrijver, C.; Shine, R.; Wolfson, J.; Zayer, I.; Scherrer, P.; Bush, R.; Deforest, C.; Hoeksema, T. Bibcode: 1996AAS...188.6915T Altcode: 1996BAAS...28..938T The Michelson Doppler Imager (MDI) on SoHO takes magnetogram s with resolutions of 1.2 (high resolution) and 4 (full disk) arcseconds. Movies of 16 hour duration have been constructed in full disk and high resolution mode. High resolution movies of the south polar region also have been obtained. In sums of nine high resolution magnetograms it is possible to detect fields as low as 5 gauss and total fluxes as low as 5 10(1) 6 Mx. In mid latitude regions new flux is observed to emerge everywhere. At all latitudes below 60 degrees flux is mixed on the scale of supergranulation. In the polar region above 60 degrees only fields of a single polarity are observed above the detection limit. Title: SOI/MDI Measurements of Horizontal Flows in the South Polar Region of the Sun by Correlation Tracking and Doppler Shifts Authors: Simon, G.; Frank, Z.; Hurlburt, N.; Schrijver, C.; Shine, R.; Tarbell, T.; Title, A.; Deforest, C. Bibcode: 1996AAS...188.6913S Altcode: 1996BAAS...28R.937S On 7 March 1996, the SOHO spacecraft was offset from its usual disk center pointing for an 11-hour observation of the South Polar region. MDI took a continuous time series of high resolution longitudinal magnetograms during this period, in support of the SOHO-wide Joint Observing Program on polar plumes. It also ran several hours each of two other programs: one to map the horizontal flows near the pole by correlation tracking and Doppler shifts, and another to study wave propagation (e.g., by time-distance helioseismology) at these high latitudes. In this poster we present preliminary results from the first program. Both techniques yield measurements of the differential rotation profile near the pole and of horizontal flows of supergranulation. These results are compared with each other and with corresponding measurements in low latitudes. The location of magnetic features in the horizontal flows is also shown. The SOI/MDI program is supported by NASA grant NAG5-3077. Title: Multi-Spectral Solar Telescope Array IX: quantitative measurements of the solar corona Authors: DeForest, Craig E.; Walker, Arthur B.; Allen, Maxwell J.; Hoover, Richard B.; Barbee, Troy W. Bibcode: 1995SPIE.2515..273D Altcode: The Multi-Spectral Solar Telescope Array (MSSTA) is a rocket borne cluster of normal- incidence multilayer coated telescopes for the high-resolution study of the solar atmosphere and corona. In previous papers, we have described the design, calibration, and flight of the MSSTA, and reported qualitative results of those solar observations. In the present paper, we describe the MSSTA's measured quantitative instrument response to the optically thin solar coronal plasma, and present an example of the derivation of solar temperature and density diagnostic information from four photographic images obtained during the instrument's successful inaugural flight in 1991. Title: Design and performance of thin foil XUV filters for the Multi-Spectral Solar Telescope Array II Authors: Plummer, James E.; DeForest, Craig E.; Martinez-Galarce, Dennis S.; Kankelborg, Charles C.; Gore, David B.; O'Neal, Ray H.; Walker, Arthur B.; Powell, Forbes R.; Hoover, Richard B.; Barbee, Troy W.; Weed, J. W. Bibcode: 1995SPIE.2515..565P Altcode: The redesigned payload of the Multi-Spectral Solar Telescope Array (MSSTA), the MSSTA II, was successfully flown on November 3, 1994. The multilayer mirrors used in the normal incidence optical systems of the MSSTA II are efficient reflectors for soft x-ray/extreme ultraviolet (EUV) radiation at wavelengths that satisfy the Bragg condition, thus allowing a narrow band of the soft x-ray/EUV spectrum to be isolated. When applied to solar observations the temperature response of an optical system is quite sensitive to telescope bandpass because of the high density of lines in the coronal spectrum. We have designed a set of thin foil filters in conjunction with our multilayer optics to eliminate contaminant lines and specular reflectivity, thus enhancing the temperature diagnostic capabilities of our instruments. Extensive measurements have recently been carried out on the thin foil filters at the Stanford Synchrotron Radiation Laboratory. We describe here the design and performance of thin foil filters developed for the MSSTA II. Title: Multi-Spectral Solar Telescope Array VIII: the second flight Authors: Walker, Arthur B.; Allen, Maxwell J.; DeForest, Craig E.; Kankelborg, Charles C.; Martinez-Galarce, Dennis S.; Plummer, James E.; Hoover, Richard B.; Barbee, Troy W.; Gore, David B. Bibcode: 1995SPIE.2515..182W Altcode: The Multi Spectral Solar Telescope Array (MSSTA) is a rocket borne observatory that utilizes an array of multi-layer and interference film coated telescopes to observe the solar atmosphere from the chromosphere to the corona, over a broad spectral range (VUV - soft x rays). The MSSTA is continuously evolved to incorporate new instruments, and to improve its ability to investigate specific topics related to the structure and dynamics of the solar atmosphere. We describe chromospheric and coronal observations recorded during the second flight of the MSSTA on November 3, 1994 at 1915 UT. Title: Calibration of multilayer mirrors for the Multi-Spectral Solar Telescope Array II Authors: Kankelborg, Charles C.; Plummer, James E.; Martinez-Galarce, Dennis S.; O'Neal, Ray H.; DeForest, Craig E.; Walker, Arthur B.; Barbee, Troy W.; Weed, J. W.; Hoover, Richard B.; Powell, Forbes R. Bibcode: 1995SPIE.2515..436K Altcode: The Multi-Spectral Solar Telescope Array II (MSSTA II), a rocket-borne solar observatory, was successfully flown on November 3, 1994 obtaining solar images in multiple XUV and FUV bands with an array of compact multilayer telescopes. Extensive measurements have recently been carried out on some of the multilayer telescopes at the Stanford Synchrotron Radiation Laboratory. These measurements are the first high spectral resolution calibrations of newly introduced MSSTA II instruments and instruments with lambda0 less than 130 angstrom. Previous measurements and/or calculations of telescope throughputs have been confirmed with greater accuracy. Results are presented on Mo/Si multilayer bandpasses, and multilayer bandpass changes with time. Title: Multi-Spectral Observation and Modeling of Polar Plumes in the Solar Corona Authors: Deforest, C. E.; Walker, A. B. C., Jr.; Hoover, R. B.; Barbee, T. W., Jr. Bibcode: 1995SPD....26..604D Altcode: 1995BAAS...27..961D No abstract at ADS Title: High-Resolution Multi-Spectral Observations of Solar Coronal Open Structures: Polar and Equatorial Plumes and Rays. Authors: Deforest, Craig Edward Bibcode: 1995PhDT........10D Altcode: XUV emissions from the lower corona (R ~1.5 R odot) have been observed by the Multi-Spectral Solar Telescope Array (MSSTA), a cluster of normal-incidence XUV telescopes that flew in 1991 and 1994, and by the MSSTA's predecessor, the Stanford/MSFC/LLNL Rocket Spectroheliograph, in 1987. In 1987 and 1994, observations of the Sun at 173 A and comparison with concurrent magnetogram images, show narrow ( ~10 arc sec), radially expanding polar plumes with unipolar footpoints in the polar coronal holes. The 1991 observation, taken near solar maximum, does not show these features over the poles of the Sun, though plume -like footpoints are observed. The 1991 observation does show another class of plume, "Equatorial plumes", that have narrow (~10 arc sec) footpoints which appear to be unipolar, and that expand super-radially with a solid angle expansion factor of ~25 at R = 2 R odot. In this dissertation, I provide a brief overview of some previous observations and of our instruments (Chap. I), describe the MSSTA instruments' theoretical response to the coronal plasma (Chap. II), and present quantitative results of these observations (Chaps. III and IV). A brace of appendices describe some details of the MSSTA film calibration, and illustrate the filter design process that was used for the 1994 flight. Title: High-resolution multi-spectral observations of solar coronal open structures: Polar and equatorial plumes and rays Authors: DeForest, Craig Edward Bibcode: 1995PhDT.......173D Altcode: No abstract at ADS Title: Performance of the multilayer-coated mirrors for the MultiSpectral Solar Telescope Array Authors: Allen, Maxwell J.; Willis, Thomas D.; Kankelborg, Charles C.; O'Neal, Ray H.; Martinez-Galarce, Dennis S.; Deforest, Craig E.; Jackson, Lisa R.; Plummer, James D.; Walker, Arthur B.; Barbee, Troy W.; Weed, J. W.; Hoover, Richard B. Bibcode: 1994SPIE.2011..381A Altcode: The Multi-Spectral Solar Telescope Array, a rocket-borne solar observatory, was successfully flown in May, 1991, obtaining solar images in eight XUV and FUV bands with 12 compact multilayer telescopes. We report on recent measurements of the performance of multilayer coated mirrors for the Multi Spectral Solar Telescope Array, carried out at the Stanford Synchrotron Radiation Laboratory. Title: X-ray/EUV/FUV calibration of photographic films for solar research Authors: Hoover, Richard B.; Walker, Arthur B.; Deforest, Craig E.; Allen, Maxwell J.; Gore, David B. Bibcode: 1994SPIE.2011..504H Altcode: Film was chosen as the detector for the Multi-Spectral Solar Telescope Array (MSSTA), a sub-orbital solar observatory designed to operate over the entire soft x-ray, extreme ultraviolet (EUV), and far ultraviolet (FUV) spectral regime. In order to accurately calibrate the solar images obtained on the initial May 13, 1991 MSSTA flight, and to optimize the film loads for the diverse telescopes being developed for the MSSTA re-flight, we performed extensive calibrations at the NIST SURF II and the Stanford Synchrotron Radiation Laboratory synchrotrons. In addition to detailed studies of the MSSTA flight films (XUV-100 and 649), we also measured the performance characteristics of Kodak Technical Pan 2415 film, and the Agfa 10E56, 10E75 and Ilford HOTEC holographic emulsions. These measurements yielded valuable information concerning the soft x-ray/EUV/FUV response of the films and provided important insights into the physical properties of the films and their behavior after prolonged exposure to high vacuum. Title: Thermal and Density Structure of Polar Plumes Authors: Walker, A. B. C., Jr.; Deforest, C. E.; Hoover, R. B.; Barbee, T. W., Jr. Bibcode: 1993SoPh..148..239W Altcode: Normal incidence multilayer coated EUV/XUV optical systems provide a powerful technique for the study of the structure of the solar corona. Such systems permit the imaging of the full solar disk and corona with high angular resolution in narrow wavelength bands that are dominated by a single line or a line multiplet excited over a well defined range of temperatures. We have photometrically analysed, and derived temperature and density information from, images of polar plumes obtained with a multilayer Cassegrain telescope operating in the wavelength interval λ = 171 to 175 å, which is dominated by FeIX and FeX emission. This observation was obtained in October 1987, and is the first high resolution observation of an astronomical object obtained with normal incidence multilayer optics techniques. We find that photometric data taken from this observation, applied to a simple, semi-empirical model of supersonic solar wind flow, are consistent with the idea that polar plumes are a source of the solar wind. However, we are not able to uniquely trace high speed streams to polar plumes. The temperatures that we observed are typically ∼ 1 500 000 K for both the plumes and the interplume regions, with the plume temperatures slightly higher than those of the surrounding atmosphere. Typical electron densities of the plume and interplume regions, respectively, are 5 × 109 cm−3 and 1 × 108 cm−3 at the limb of the Sun. Title: Thermal and Density Structure of Polar Polumes II: Analysis of the Transition to the Solar Wind, using EUV and Visible Light Observations Authors: Deforest, C. E.; Walker, A. B. C., Jr.; Sime, D.; Hoover, R. B.; Barbee, T. W., Jr. Bibcode: 1993BAAS...25.1203D Altcode: No abstract at ADS Title: Ultrahigh-resolution photographic films for x-ray/EUV/FUV astronomy Authors: Hoover, Richard B.; Walker, Arthur B. C., Jr.; Deforest, Craig E.; Watts, Richard; Tarrio, Charles Bibcode: 1993SPIE.1742..549H Altcode: The quest for ultrahigh resolution full-disk images of the Sun at soft x-ray/EUV/FUV wavelengths has increased the demand for photographic films with broad spectral sensitivity, high spatial resolution, and wide dynamic range. These requirements were made more stringent by the recent development of multilayer telescopes and coronagraphs capable of operating at normal incidence at soft x-ray/EUV wavelengths. Photographic films are the only detectors now available with the information storage capacity and dynamic range such as is required for recording images of the solar disk and corona simultaneously witharc second spatial resolution. During the Stanford/MSFC/LLNL Rocket X-Ray Spectroheliograph and Multi-Spectral Solar Telescope Array (MSSTA) programs, we utilized photographic films to obtain high resolution full-disk images of the Sun at selected soft x-ray/EUV/FUV wavelengths. In order to calibrate our instrumentation for quantitative analysis of our solar data and to select the best emulsions and processing conditions for the MSSTA reflight, we recently tested several photographic films. These studies were carried out at the NIST SURF II synchrotron and the Stanford Synchrotron Radiation Laboratory. In this paper, we provide the results of those investigations. Title: Calibration of the multispectral solar telescope array multilayer mirrors and XUV filters Authors: Allen, Maxwell J.; Willis, Thomas D.; Kankelborg, Charles C.; O'Neal, Ray H.; Martinez-Galarce, Dennis S.; Deforest, Craig E.; Jackson, Lisa R.; Lindblom, Joakim F.; Walker, Arthur B.; Barbee, Troy W., Jr.; Weed, J. W.; Hoover, Richard B.; Powell, Forbes R. Bibcode: 1993SPIE.1742..562A Altcode: The Multi-Spectral Solar Telescope Array (MSSTA), rocket-borne solar observatory, was successfully flown in May, 1991, obtaining solar images in eight XUV and FUV bands with 12 compact multilayer telescopes. Extensive measurements have recently been carried out on the multilayer telescopes and thin film filters at the Stanford Synchrotron Radiation Laboratory. These measurements are the first high spectral resolution calibrations of the MSSTA instruments. Previous measurements and/or calculations of telescope throughputs have been confirmed with greater accuracy. Results are presented on Mo/Si multilayer bandpass changes with time and experimental potassium bromide and tellurium filters. Title: The density structure of polar plumes. Authors: Walker, A. B. C., Jr.; Deforest, C. E.; Barbee, T. W., Jr.; Hoover, R. B. Bibcode: 1992BAAS...24.1073W Altcode: No abstract at ADS Title: Solar observations with the Multi-Spectral Solar Telescope Array Authors: Hoover, Richard B.; Walker, Arthur B. C., Jr.; Lindblom, Joakim; Allen, Maxwell; O'Neal, Ray; Deforest, Craig; Barbee, Troy W., Jr. Bibcode: 1992SPIE.1546..175H Altcode: The Multi-Spectral Solar Telescope Array (MSSTA) is a sounding rocket-borne solar observatory which was succesfully launched on May 13, 1991, from the White Sands Missile Range, NM. Ultrahigh resolution, full-disk solar X-ray, EUV, and FUV images were obtained with the MSSTA Herschelian, Cassegrain, and Ritchey-Chretien telescopes. We describe the payload and provide some preliminary scientific results from the flight. Title: The Multi-Spectral Solar Telescope Array. II - Soft X-ray/EUV reflectivity of the multilayer mirrors Authors: Barbee, Troy W., Jr.; Weed, J. W.; Hoover, Richard B. C., Jr.; Allen, Max J.; Lindblom, Joakim F.; O'Neal, Ray H.; Kankelborg, Charles C.; Deforest, Craig E.; Paris, Elizabeth S.; Walker, Arthur B. C. Bibcode: 1992SPIE.1546..432B Altcode: 1992SPIE.2011..432B We have developed seven compact soft X-ray/EUV (XUV) multilayer coated and two compact FUV interference film coated Cassegrain and Ritchey-Chretien telescopes for a rocket borne observatory, the Multi-Spectral Solar Telescope Array. We report here on extensive measurements of the efficiency and spectral bandpass of the XUV telescopes carried out at the Stanford Synchrotron Radiation Laboratory. Title: Photographic films for the Multi-Spectral Solar Telescope Array Authors: Hoover, Richard B.; Walker, Arthur B. C., Jr.; Deforest, Craig E.; Allen, Maxwell J.; Lindblom, Joakim F.; Gilliam, Lou; November, Larry; Brown, Todd; Dewan, Clyde A. Bibcode: 1992SPIE.1546..188H Altcode: 1992SPIE.2011..188H The rocketborne Multi-Spectral Solar Telescope Array (MSSTA) uses an array of Ritchey-Chretien, Cassegrain, and Herschelian telescopes to produce ultrahigh-resolution full-disk images of the sun within the soft X-ray, EUV, and FUV ranges. Such imaging of the solar disk and corona out to several solar radii placed great demands on the MSSTA's data storage capabilities; in addition, its photographic films required very low outgassing rates. Results are presented from calibration tests conducted on the MSSTA's emulsions, based on measurements at NIST's synchrotron facility. Title: Performance of the Multi-Spectral Solar Telescope Array. Pt. 3. Optical characteristics of the Ritchey-Chrétien and Cassegrain telescopes. Authors: Hoover, Richard B.; Baker, Phillip C.; Hadaway, James B.; Johnson, R. B.; Peterson, Cynthia; Gabardi, David R.; Walker, Arthur B., Jr.; Lindblom, J. F.; Deforest, Craig; O'Neal, R. H. Bibcode: 1991SPIE.1343..189H Altcode: The Multi-Spectral Solar Telescope Array (MSSTA) is a sounding rocket borne observatory for investigations of the Sun in the soft X-ray/EUV and FUV regimes of the electromagnetic spectrum. At soft X-ray wavelengths (λλ < 100 Å), the MSSTA utilizes single reflection multilayer coated Herschelian telescopes. For selected wavelengths in the EUV (100 - 1000 Å) the MSSTA employs five doubly reflecting, multilayer coated Ritchey-Chrétien and two Cassegrain telescopes. In the FUV (λλ > 1000 Å) the MSSTA utilizes two Ritchey-Chrétien telescopes, with optics coated with thin film interference coatings. The authors describe the interferometric alignment, testing, focusing, visible light testing, and optical performance characteristics of the Ritchey-Chrétien and Cassegrain telescopes. Title: Multi-spectral solar telescope array. V. Temperature diagnostic response to the optically thin solar plasma. Authors: Deforest, C. E.; Krankelborg, C. C.; Allen, M. J.; Paris, E. S.; Willis, T. D.; Lindblom, J. F.; O'Neal, R. H.; Walker, A. B. C., Jr.; Barbee, T. W., Jr.; Hoover, R. B.; Barbee, T. W., III Bibcode: 1991OptEn..30.1125D Altcode: The authors have developed compact soft X-ray, extreme ultraviolet (EUV), and far-ultraviolet multilayer coated telescopes for the study of the solar chromosphere, corona, and corona/solar wind interface. In addition to permitting traditional normal incidence optical configurations to be used at soft X-ray/EUV wavelengths, multilayer coatings also allow a narrow wavelength band (λ/Δλ ≡ 15 - 100) to be selected for imaging. The resulting telescopes provide a very powerful and flexible diagnostic instrument for the study of both the fine-scale structure of the chromosphere/corona interface and the large-scale structure of the corona and corona/solar wind interface. The authors report on the ability of the MSSTA payload to obtain temperature diagnostic information about the optically thin solar plasma. They also discuss applications of this information to studies of coronal structure. Title: EUV/FUV response characteristics of photographic films for the multi-spectral solar telescope array. Authors: Hoover, Richard B.; Walker, Arthur B. C., Jr.; Deforest, Craig E.; Allen, Maxwell J.; Lindblom, Joakim F. Bibcode: 1991OptEn..30.1116H Altcode: The Multi-Spectral Solar Telescope Array (MSSTA) is a sounding rocket-borne observatory designed to produce ultrahigh-resolution full-disk images of the sun. The desire for ultrahigh-resolution (≡0.1 to 0.3″ images of the solar disk and corona out to 1.5 Rsun demands an information storage capacity that at the present time can be met only by the highest quality photographic emulsions. The authors describe the performance and characteristics required of the MSSTA photographic films for solar observations in the soft X-ray/EUV and FUV wavelength regimes. They discuss the properties of the important new emulsions selected for flight. Title: Multi-spectral solar telescope array II: Soft X-ray/EUV reflectivity of the multilayer mirrors. Authors: Barbee, T. W., Jr.; Weed, J. W.; Hoover, R. B.; Allen, M. J.; Lindblom, J. F.; O'Neal, R. H.; Kankelborg, C. C.; Deforest, C. E.; Paris, E. S.; Walker, A. B. C., Jr.; Willis, T. D.; Gluskin, E.; Pianetta, P.; Baker, P. C. Bibcode: 1991OptEn..30.1067B Altcode: The authors have developed seven compact soft X-ray/EUV (XUV) multilayer-coated and two compact FUV interference-film-coated Cassegrain and Ritchey-Chrétien telescopes for a rocket-borne observatory, the Multi-Spectral Solar Telescope Array. They report on extensive measurements of the efficiency and spectral bandpass of the XUV telescopes. Title: The Density Structure of Polar Plumes Authors: Walker, A. B. C., Jr.; Lindblom, J. F.; Deforest, C. E.; Paris, E. S.; Allen, M. J.; Hoover, R. B.; Barbee, T. W., Jr. Bibcode: 1991BAAS...23.1264W Altcode: No abstract at ADS Title: The Ultra High Resolution XUV Spectroheliograph. Pt. 2. Predicted performance. Authors: Walker, A. B. C., Jr.; Lindblom, J. F.; Timothy, J. G.; Allen, M. J.; Deforest, C. E.; Kankelborg, C.; O'Neal, R. H.; Paris, E. S.; Willis, T.; Barbee, T. W., Jr.; Hoover, R. B. Bibcode: 1991SPIE.1343..319W Altcode: The authors have developed an Ultra High Resolution XUV Spectroheliograph (UHRXS) for flight among the initial scientific instruments to be placed on the Space Station "Freedom". The principal UHRXS instruments are nine multilayer Ritchey-Chrétien telescopes covering the spectral range from ≡70 Å to ≡300 Å. The XUV images will be recorded on high resolution photographic film, allowing angular resolutions as high as 0.1″to be achieved for a 1.0° field. The authors present an analysis of the expected sensitivity and resolving power of the UHRXS telescopes, and the diagnostic response of the various UHRXS instruments to structures in the solar atmosphere between 10,000K and 100,000,000K. Title: Performance of the Multi-Spectral Solar Telescope Array VI: performance and characteristics of the photographic films Authors: Hoover, Richard B.; Walker, Arthur B.; Deforest, Craig E.; Allen, Maxwell J.; Lindblom, Joakim F. Bibcode: 1991SPIE.1343..175H Altcode: No abstract at ADS Title: Performance of the Multi-Spectral Solar Telescope Array V: temperature diagnostic response to the optically thin solar plasma Authors: Deforest, Craig E.; Kankelborg, Charles C.; Allen, Maxwell J.; Paris, Elizabeth S.; Willis, Thomas D.; Lindblom, Joakim F.; O'Neal, Ray H.; Walker, Arthur B.; Barbee, Troy W.; Hoover, Richard B.; Barbee, Troy W.; Gluskin, Efim S. Bibcode: 1991SPIE.1343..404D Altcode: No abstract at ADS Title: Performance of compact multilayer coated telescopes at soft x-ray/EUV and far-ultraviolet wavelengths I Authors: Hoover, Richard B.; Barbee, Troy W.; Baker, Phillip C.; Lindblom, Joakim F.; Allen, Maxwell J.; Deforest, Craig E.; Kankelborg, Charles C.; O'Neal, Ray H.; Paris, Elizabeth S.; Walker, Arthur B. Bibcode: 1990SPIE.1235..821H Altcode: No abstract at ADS Title: Multi-Spectral Solar Telescope Array Authors: Walker, A. B. C., Jr.; Allen, M. J.; Deforest, C.; Kankelborg, C.; Lindblom, J. F.; O'Neal, R. H.; Paris, E.; Hoover, R. B.; Barbee, T. W., Jr. Bibcode: 1990BAAS...22..808W Altcode: No abstract at ADS