Author name code: davila ADS astronomy entries on 2022-09-14 author:"Davila, Joseph" ------------------------------------------------------------------------ Title: Coordination within the remote sensing payload on the Solar Orbiter mission Authors: Auchère, F.; Andretta, V.; Antonucci, E.; Bach, N.; Battaglia, M.; Bemporad, A.; Berghmans, D.; Buchlin, E.; Caminade, S.; Carlsson, M.; Carlyle, J.; Cerullo, J. J.; Chamberlin, P. C.; Colaninno, R. C.; Davila, J. M.; De Groof, A.; Etesi, L.; Fahmy, S.; Fineschi, S.; Fludra, A.; Gilbert, H. R.; Giunta, A.; Grundy, T.; Haberreiter, M.; Harra, L. K.; Hassler, D. M.; Hirzberger, J.; Howard, R. A.; Hurford, G.; Kleint, L.; Kolleck, M.; Krucker, S.; Lagg, A.; Landini, F.; Long, D. M.; Lefort, J.; Lodiot, S.; Mampaey, B.; Maloney, S.; Marliani, F.; Martinez-Pillet, V.; McMullin, D. R.; Müller, D.; Nicolini, G.; Orozco Suarez, D.; Pacros, A.; Pancrazzi, M.; Parenti, S.; Peter, H.; Philippon, A.; Plunkett, S.; Rich, N.; Rochus, P.; Rouillard, A.; Romoli, M.; Sanchez, L.; Schühle, U.; Sidher, S.; Solanki, S. K.; Spadaro, D.; St Cyr, O. C.; Straus, T.; Tanco, I.; Teriaca, L.; Thompson, W. T.; del Toro Iniesta, J. C.; Verbeeck, C.; Vourlidas, A.; Watson, C.; Wiegelmann, T.; Williams, D.; Woch, J.; Zhukov, A. N.; Zouganelis, I. Bibcode: 2020A&A...642A...6A Altcode: Context. To meet the scientific objectives of the mission, the Solar Orbiter spacecraft carries a suite of in-situ (IS) and remote sensing (RS) instruments designed for joint operations with inter-instrument communication capabilities. Indeed, previous missions have shown that the Sun (imaged by the RS instruments) and the heliosphere (mainly sampled by the IS instruments) should be considered as an integrated system rather than separate entities. Many of the advances expected from Solar Orbiter rely on this synergistic approach between IS and RS measurements.
Aims: Many aspects of hardware development, integration, testing, and operations are common to two or more RS instruments. In this paper, we describe the coordination effort initiated from the early mission phases by the Remote Sensing Working Group. We review the scientific goals and challenges, and give an overview of the technical solutions devised to successfully operate these instruments together.
Methods: A major constraint for the RS instruments is the limited telemetry (TM) bandwidth of the Solar Orbiter deep-space mission compared to missions in Earth orbit. Hence, many of the strategies developed to maximise the scientific return from these instruments revolve around the optimisation of TM usage, relying for example on onboard autonomy for data processing, compression, and selection for downlink. The planning process itself has been optimised to alleviate the dynamic nature of the targets, and an inter-instrument communication scheme has been implemented which can be used to autonomously alter the observing modes. We also outline the plans for in-flight cross-calibration, which will be essential to the joint data reduction and analysis.
Results: The RS instrument package on Solar Orbiter will carry out comprehensive measurements from the solar interior to the inner heliosphere. Thanks to the close coordination between the instrument teams and the European Space Agency, several challenges specific to the RS suite were identified and addressed in a timely manner. Title: Models and data analysis tools for the Solar Orbiter mission Authors: Rouillard, A. P.; Pinto, R. F.; Vourlidas, A.; De Groof, A.; Thompson, W. T.; Bemporad, A.; Dolei, S.; Indurain, M.; Buchlin, E.; Sasso, C.; Spadaro, D.; Dalmasse, K.; Hirzberger, J.; Zouganelis, I.; Strugarek, A.; Brun, A. S.; Alexandre, M.; Berghmans, D.; Raouafi, N. E.; Wiegelmann, T.; Pagano, P.; Arge, C. N.; Nieves-Chinchilla, T.; Lavarra, M.; Poirier, N.; Amari, T.; Aran, A.; Andretta, V.; Antonucci, E.; Anastasiadis, A.; Auchère, F.; Bellot Rubio, L.; Nicula, B.; Bonnin, X.; Bouchemit, M.; Budnik, E.; Caminade, S.; Cecconi, B.; Carlyle, J.; Cernuda, I.; Davila, J. M.; Etesi, L.; Espinosa Lara, F.; Fedorov, A.; Fineschi, S.; Fludra, A.; Génot, V.; Georgoulis, M. K.; Gilbert, H. R.; Giunta, A.; Gomez-Herrero, R.; Guest, S.; Haberreiter, M.; Hassler, D.; Henney, C. J.; Howard, R. A.; Horbury, T. S.; Janvier, M.; Jones, S. I.; Kozarev, K.; Kraaikamp, E.; Kouloumvakos, A.; Krucker, S.; Lagg, A.; Linker, J.; Lavraud, B.; Louarn, P.; Maksimovic, M.; Maloney, S.; Mann, G.; Masson, A.; Müller, D.; Önel, H.; Osuna, P.; Orozco Suarez, D.; Owen, C. J.; Papaioannou, A.; Pérez-Suárez, D.; Rodriguez-Pacheco, J.; Parenti, S.; Pariat, E.; Peter, H.; Plunkett, S.; Pomoell, J.; Raines, J. M.; Riethmüller, T. L.; Rich, N.; Rodriguez, L.; Romoli, M.; Sanchez, L.; Solanki, S. K.; St Cyr, O. C.; Straus, T.; Susino, R.; Teriaca, L.; del Toro Iniesta, J. C.; Ventura, R.; Verbeeck, C.; Vilmer, N.; Warmuth, A.; Walsh, A. P.; Watson, C.; Williams, D.; Wu, Y.; Zhukov, A. N. Bibcode: 2020A&A...642A...2R Altcode: Context. The Solar Orbiter spacecraft will be equipped with a wide range of remote-sensing (RS) and in situ (IS) instruments to record novel and unprecedented measurements of the solar atmosphere and the inner heliosphere. To take full advantage of these new datasets, tools and techniques must be developed to ease multi-instrument and multi-spacecraft studies. In particular the currently inaccessible low solar corona below two solar radii can only be observed remotely. Furthermore techniques must be used to retrieve coronal plasma properties in time and in three dimensional (3D) space. Solar Orbiter will run complex observation campaigns that provide interesting opportunities to maximise the likelihood of linking IS data to their source region near the Sun. Several RS instruments can be directed to specific targets situated on the solar disk just days before data acquisition. To compare IS and RS, data we must improve our understanding of how heliospheric probes magnetically connect to the solar disk.
Aims: The aim of the present paper is to briefly review how the current modelling of the Sun and its atmosphere can support Solar Orbiter science. We describe the results of a community-led effort by European Space Agency's Modelling and Data Analysis Working Group (MADAWG) to develop different models, tools, and techniques deemed necessary to test different theories for the physical processes that may occur in the solar plasma. The focus here is on the large scales and little is described with regards to kinetic processes. To exploit future IS and RS data fully, many techniques have been adapted to model the evolving 3D solar magneto-plasma from the solar interior to the solar wind. A particular focus in the paper is placed on techniques that can estimate how Solar Orbiter will connect magnetically through the complex coronal magnetic fields to various photospheric and coronal features in support of spacecraft operations and future scientific studies.
Methods: Recent missions such as STEREO, provided great opportunities for RS, IS, and multi-spacecraft studies. We summarise the achievements and highlight the challenges faced during these investigations, many of which motivated the Solar Orbiter mission. We present the new tools and techniques developed by the MADAWG to support the science operations and the analysis of the data from the many instruments on Solar Orbiter.
Results: This article reviews current modelling and tool developments that ease the comparison of model results with RS and IS data made available by current and upcoming missions. It also describes the modelling strategy to support the science operations and subsequent exploitation of Solar Orbiter data in order to maximise the scientific output of the mission.
Conclusions: The on-going community effort presented in this paper has provided new models and tools necessary to support mission operations as well as the science exploitation of the Solar Orbiter data. The tools and techniques will no doubt evolve significantly as we refine our procedure and methodology during the first year of operations of this highly promising mission. 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: Improving Coronal Magnetic Field Models Using Image Optimization Authors: Jones, Shaela I.; Uritsky, Vadim M.; Davila, Joseph M.; Troyan, Vladimir N. Bibcode: 2020ApJ...896...57J Altcode: We have reported previously on our development and testing of a new method for using coronal images to improve coronal magnetic field models. In this technique, which we call image-optimization, coronal magnetic field models are extrapolated from synoptic photospheric magnetograms. The resulting models are then compared to morphological constraints derived from images of the solar corona, and the photospheric magnetograms are perturbed iteratively via an optimization algorithm to achieve optimal agreement with the image-based constraints. Here we present results from the first application of this technique using Mauna Loa Solar Observatory K-Coronagraph images and Global Oscillation Network Group synoptic magnetograms to create optimized models for two time periods, 2014 November 16-29 and 2016 May 16-29. We find that for both time periods the optimization algorithm converges well and results in better agreement between the model and the images, relatively small changes to the synoptic magnetogram, and an overall increase in the amount of open magnetic flux. Title: Coronal Magnetic Field Model Selection Using Images of the Middle Corona and Solar Wind Measurements Authors: Jones, S. I.; Arge, C. N.; Uritsky, V. M.; Henney, C. J.; Davila, J. M.; Staeben, J. H. Bibcode: 2019AGUFMSH13A..08J Altcode: In order to understand the dynamic processes taking place in the middle corona, we need a way of accurately modeling it. Numerous models are available - as well as multiple sources of boundary conditions from which to build those models - but limited measurements are available with which to compare them. Available data on the middle corona consist of images and spectroscopic measurements from a highly limited number of vantage points, and these data can be difficult to compare quantitatively with models.

Recently we have developed a method for such a quantitative image-model comparison using measurements from the K-Cor and STEREO COR-1 coronagraphs. We have also devised a new method for quantitative assessment of different synoptic map inputs based on comparison between WSA solar wind predictions and in situ data. Here we detail the two methods and compare their results. Title: Slitless Solar Imaging Spectroscopy Authors: Davila, Joseph M.; Oktem, Figen S.; Kamalabadi, Farzad Bibcode: 2019ApJ...883....7D Altcode: Spectrometers provide our most detailed diagnostics of the solar coronal plasma, and spectral data is routinely used to measure the temperature, density, and flow velocity in coronal features. However, spectrographs suffer from a limited instantaneous field of view (IFOV). Conversely, imaging instruments can provide a relatively large IFOV, but extreme-ultraviolet (EUV) multilayer imaging offers very limited spectral resolution. In this paper, we suggest an instrument concept that combines the large IFOV of an imager with the diagnostic capability of a spectrograph, develop a new parametric model to describe the instrument, and evaluate a new method for “deconvolving” the data from such an instrument. To demonstrate the operating principle of this new slitless spectroscopy instrument, actual spectroscopic raster data from the Hinode/EUV Imaging Spectrometer (EIS) spectrometer is used. We assume that observations in multiple spectral orders are obtained, and then use a new inverse problem method to infer the spectral properties. Unlike previous methods, physical constraints and regularization derived from prior knowledge can be naturally incorporated as part of the solution process. We find that the fidelity of the solution is vastly improved compared to previous methods. The errors are typically only a few km s-1 over a large IFOV, with a width of a few hundred pixels and an arbitrarily large height. These errors are not much larger than the errors in current slit spectroscopic instruments with limited IFOV. A further benefit is that the performance of candidate instruments can be optimized for specific scientific objectives. We demonstrate this by deriving optimum values for the spectral dispersion and signal-to-noise ratio. Title: Effect of Transport Coefficients on Excitation of Flare-induced Standing Slow-mode Waves in Coronal Loops Authors: Wang, Tongjiang; Ofman, Leon; Sun, Xudong; Solanki, Sami K.; Davila, Joseph M. Bibcode: 2018ApJ...860..107W Altcode: 2018arXiv180503282W Standing slow-mode waves have been recently observed in flaring loops by the Atmospheric Imaging Assembly of the Solar Dynamics Observatory. By means of the coronal seismology technique, transport coefficients in hot (∼10 MK) plasma were determined by Wang et al., revealing that thermal conductivity is nearly suppressed and compressive viscosity is enhanced by more than an order of magnitude. In this study, we use 1D nonlinear MHD simulations to validate the predicted results from the linear theory and investigate the standing slow-mode wave excitation mechanism. We first explore the wave trigger based on the magnetic field extrapolation and flare emission features. Using a flow pulse driven at one footpoint, we simulate the wave excitation in two types of loop models: Model 1 with the classical transport coefficients and Model 2 with the seismology-determined transport coefficients. We find that Model 2 can form the standing wave pattern (within about one period) from initial propagating disturbances much faster than Model 1, in better agreement with the observations. Simulations of the harmonic waves and the Fourier decomposition analysis show that the scaling law between damping time (τ) and wave period (P) follows τ ∝ P 2 in Model 2, while τ ∝ P in Model 1. This indicates that the largely enhanced viscosity efficiently increases the dissipation of higher harmonic components, favoring the quick formation of the fundamental standing mode. Our study suggests that observational constraints on the transport coefficients are important in understanding both the wave excitation and damping mechanisms. Title: Evaluating Uncertainties in Coronal Electron Temperature and Radial Speed Measurements Using a Simulation of the Bastille Day Eruption Authors: Reginald, Nelson; St. Cyr, Orville; Davila, Joseph; Rastaetter, Lutz; Török, Tibor Bibcode: 2018SoPh..293...82R Altcode: Obtaining reliable measurements of plasma parameters in the Sun's corona remains an important challenge for solar physics. We previously presented a method for producing maps of electron temperature and speed of the solar corona using K-corona brightness measurements made through four color filters in visible light, which were tested for their accuracies using models of a structured, yet steady corona. In this article we test the same technique using a coronal model of the Bastille Day (14 July 2000) coronal mass ejection, which also contains quiet areas and streamers. We use the coronal electron density, temperature, and flow speed contained in the model to determine two K-coronal brightness ratios at (410.3, 390.0 nm) and (423.3, 398.7 nm) along more than 4000 lines of sight. Now assuming that for real observations, the only information we have for each line of sight are these two K-coronal brightness ratios, we use a spherically symmetric model of the corona that contains no structures to interpret these two ratios for electron temperature and speed. We then compare the interpreted (or measured) values for each line of sight with the true values from the model at the plane of the sky for that same line of sight to determine the magnitude of the errors. We show that the measured values closely match the true values in quiet areas. However, in locations of coronal structures, the measured values are predictably underestimated or overestimated compared to the true values, but can nevertheless be used to determine the positions of the structures with respect to the plane of the sky, in front or behind. Based on our results, we propose that future white-light coronagraphs be equipped to image the corona using four color filters in order to routinely create coronal maps of electron density, temperature, and flow speed. Title: Ultrahigh-Resolution Solar Imaging with Diffractive Optics Authors: Rabin, Douglas; Davila, Joseph M.; Daw, Adrian Nigel; Denis, Kevin; Shah, Neerav; Mason, Emily; Novo-Gradac, Anne-Marie; Widmyer, Thomas Bibcode: 2018tess.conf40443R Altcode: Extreme ultraviolet (EUV) and soft X-ray (SXR) telescopes rarely achieve diffraction-limited performance because conventional reflective optics of the required size typically cannot be manufactured to the requisite figure accuracy. Diffractive optics can overcome the angular-resolution limitations of EUV/SXR mirrors but present other design and performance challenges. A diffractive telescope is well-suited for probing for the first time the expected energy dissipation scales of the solar corona (<100 km). We have previously described the fabrication of photon sieves and Fresnel zone plates as large as 80-mm clear aperture, as well as laboratory measurements and vibration testing. Here we report on the design of more efficient phase zone plates, the path to larger apertures, and our approach to a virtual telescope based on formation-flying smallsats. Title: Evaluating Uncertainties in Coronal Electron Temperature and Radial Speed Measurements Using a Simulation of the Bastille-Day Eruption Authors: Reginald, Nelson Leslie; St Cyr, O. C.; Davila, Joseph M.; Rastaetter, Lutz; Torok, Tibor Bibcode: 2018tess.conf10410R Altcode: Obtaining reliable measurements of plasma parameters in the Sun's corona remains an important challenge for solar physics. We have previously conducted field experiments using MACS and ISCORE instruments to create maps of electron temperature and speed in the plane of the sky of the solar corona using K-corona brightness measurements made through four color filters in visible light. These instrumental techniques were tested for their accuracy by conducting synthetic observations on models that contained streamers and quiet areas and results were presented in (Reginald et al., 2014, Solar Phys., 289, 2021). Here, we present similar results from conducting synthetic observations on a coronal model of the Bastille-Day (July 14, 2000) coronal mass ejection that also contains streamers and quiet regions. We use the coronal electron density, temperature, and flow speed contained in the Bastille-Day model to determine two K-coronal brightness ratios at (410.0, 390.0 nm) and (423.3, 398.7 nm) along more than 4000 lines of sight on eight select frames. Now assuming that, for real observations, the only information we have for each line of sight are these two K-coronal brightness ratios, we then use a spherically symmetric model of the corona that contains no structures to interpret these two ratios for electron temperature and speed in the plane of the sky. Finally, for each line of sight, we compare the interpreted (or measured) value with the true value from the Bastille-Day model in the plane of the sky to determine the magnitude of the error. An example of the three step process applied on one frame in the Bastille-Day model is shown in the image. We show that the measured values closely match the true values in quiet areas. However, in locations of coronal structures the measured values are predictably underestimated or overestimated over the true values, but can nevertheless be used to determine the positions of the structures with respect to the plane of the sky, in front or behind. Our results show the potential for future white-light coronagraphs be equipped with four color filters instead of the customary single filter to produce synoptic maps of electron density, temperature and flow speed in the plane of the sky. Title: Excitation and Damping of Standing Slow-Mode Waves in Flaring Coronal Loops Authors: Wang, Tongjiang; Ofman, Leon; Sun, Xudong; Solanki, Sami K.; Davila, Joseph M. Bibcode: 2018tess.conf22204W Altcode: We analyze and model a flare-induced longitudinal oscillation event detected by SDO/AIA. The magnetic field extrapolation and flare emission features suggest that the wave event is generated by slipping and null-point-type reconnections in a closed fan-spine magnetic topology, and the large spine loop appears to be heated impulsively to the flare temperature before the wave disturbances travel along it. By means of the seismology technique, we determined the transport coefficients in hot (about 10 MK) plasma, and found that thermal conductivity is nearly suppressed and compressive viscosity is enhanced by more than an order of magnitude from the observed wave properties. Using a flow pulse injected at the loop's footpoint constrained by the observation, we simulate the excitation of slow-mode waves in two types of 1D loop models. We find that the models with the seismology-determined transport coefficients can excite the standing waves quickly as observed, while the models with the classical transport coefficients excites basically the reflecting propagating waves. Simulations of harmonic waves and the Fourier decomposition analysis reveal a scaling between damping time and wave period as Td ~ P in the former type of models, while Td ~ P2 in the latter type. This suggests that anomalously large viscosity can efficiently enhance the dissipation of higher harmonic components, favoring quick setup of the fundamental standing mode. Our study indicates that observational constraints on the transport coefficients are crucial in understanding both the wave excitation and damping mechanisms. Title: Relationship between the Coronal Activity and Magnetic Flux over Solar Cycle 24 Authors: Wang, Tongjiang; Reginald, Nelson Leslie; Davila, Joseph M.; St Cyr, O. C. Bibcode: 2018tess.conf10309W Altcode: It is widely accepted that the variability of the solar white-light corona is closely connected to the solar activity. Many previous studies have revealed that the temporal variation of the total radiance of the K-corona follows the solar cycle pattern (e.g., correlated with sunspot number). However, systematic studies on the origin of the coronal mass and its variability are still rare. In this study, by means of the spherically symmetric inversion (SSI) method we reconstruct 3D coronal densities for Carrington Rotations (CRs) 2079--2180 over 2009--2017 using polarized brightness (pB) images observed with STEREO/COR1 and LASCO/C2. We calculate the total coronal mass from these density reconstructions within certain radial ranges, and compare its temporal evolution with the total magnetic flux measured from SOHO/MDI and SDO/HMI. We find a high correlation between the variations of total coronal mass and magnetic flux, and the former appears to be lagged by a CR to the latter during the rising phase of Cycle 24. To confirm this finding we also compare the observed coronal masses with those calculated from global thermodynamic MHD models by Predictive Science Inc (PSI), and compare the evolution of SDO/EVE line emissions between the chromosphere and the corona. In addition, we also explore the origin of the peaks in coronal mass and magnetic flux variations during the rising phase of Cycle 24. Title: Solar Coronagraphs from the DSG Authors: Newmark, J. S.; Davila, J. M. Bibcode: 2018LPICo2063.3079N Altcode: A solar coronagraph mounted on the Deep Space Gateway will enable unprecedented observations of the low solar corona; in particular provide key observational constraints on the initiation of Coronal Mass Ejections (CMEs). Title: Space Weather Diamond: A 10x Improvement in Real-Time Forecasting Authors: St Cyr, O. C.; Davila, J. M.; Newmark, J. Bibcode: 2018LPICo2063.3057S Altcode: Space Weather Diamond is based on a constellation of four platforms that are phased into eccentric heliocentric orbits but, from the perspective of a fixed Sun-Earth line, the spacecraft appear to orbit Earth. Title: Progress on Using Image-Optimization to Improve Coronal Magnetic Field Models Authors: Jones, Shaela; Davila, Joseph M.; Uritsky, Vadim M. Bibcode: 2018AAS...23133803J Altcode: Reliable measurements of the coronal magnetic field have proven to be very elusive. Over several decades, solar physicists have developed means of extrapolating photospheric magnetic field measurements into the corona and ultimately into the heliosphere. However, these methods can be very sensitive to the photospheric measurements, with a significant range of heliospheric conditions possible within the uncertainty of the photospheric magnetograms. Recently we have presented a method to obtain morphological information about the coronal magnetic field from coronagraph images, and to incorporate this information into a PFSS coronal magnetic field model via optimization. Here we will present details of the method and recent progress in its development, including a significant speed-up of the optimization process that allows the optimization of higher-resolution coronal models. Title: Image-based optimization of coronal magnetic field models for improved space weather forecasting Authors: Uritsky, V. M.; Davila, J. M.; Jones, S. I.; MacNeice, P. J. Bibcode: 2017AGUFMSH21A2643U Altcode: The existing space weather forecasting frameworks show a significant dependence on the accuracy of the photospheric magnetograms and the extrapolation models used to reconstruct the magnetic filed in the solar corona. Minor uncertainties in the magnetic field magnitude and direction near the Sun, when propagated through the heliosphere, can lead to unacceptible prediction errors at 1 AU. We argue that ground based and satellite coronagraph images can provide valid geometric constraints that could be used for improving coronal magnetic field extrapolation results, enabling more reliable forecasts of extreme space weather events such as major CMEs. In contrast to the previously developed loop segmentation codes designed for detecting compact closed-field structures above solar active regions, we focus on the large-scale geometry of the open-field coronal regions up to 1-2 solar radii above the photosphere. By applying the developed image processing techniques to high-resolution Mauna Loa Solar Observatory images, we perform an optimized 3D B-line tracing for a full Carrington rotation using the magnetic field extrapolation code developed S. Jones at al. (ApJ 2016, 2017). Our tracing results are shown to be in a good qualitative agreement with the large-scale configuration of the optical corona, and lead to a more consistent reconstruction of the large-scale coronal magnetic field geometry, and potentially more accurate global heliospheric simulation results. Several upcoming data products for the space weather forecasting community will be also discussed. Title: The Image-Optimized Corona; Progress on Using Coronagraph Images to Constrain Coronal Magnetic Field Models Authors: Jones, S. I.; Uritsky, V. M.; Davila, J. M. Bibcode: 2017AGUFMSH11C..06J Altcode: In absence of reliable coronal magnetic field measurements, solar physicists have worked for several decades to develop techniques for extrapolating photospheric magnetic field measurements into the solar corona and/or heliosphere. The products of these efforts tend to be very sensitive to variation in the photospheric measurements, such that the uncertainty in the photospheric measurements introduces significant uncertainty into the coronal and heliospheric models needed to predict such things as solar wind speed, IMF polarity at Earth, and CME propagation. Ultimately, the reason for the sensitivity of the model to the boundary conditions is that the model is trying to extact a great deal of information from a relatively small amout of data. We have published in recent years about a new method we are developing to use morphological information gleaned from coronagraph images to constrain models of the global coronal magnetic field. In our approach, we treat the photospheric measurements as approximations and use an optimization algorithm to iteratively find a global coronal model that best matches both the photospheric measurements and quasi-linear features observed in polarization brightness coronagraph images. Here we will summarize the approach we have developed and present recent progress in optimizing PFSS models based on GONG magnetograms and MLSO K-Cor images. Title: Remote Sensing of the Solar Wind Density, Speed, and Temperature in the Region between the Sun and Parker Solar Probe Authors: Davila, J. M.; Reginald, N. L. Bibcode: 2017AGUFMSH23D2692D Altcode: A coronagraph is the tool of choice to understand and observe the structure of the corona from space. The novel coronagraph concept presented her provides a new scientific capability that will allow the measurement of density, temperature, and flow velocity in the solar atmosphere. This instrument will provide the first remote sensing measurement of the global solar wind temperature, density, and flow speed in the regions between 3 and 8 Rsun. It is in this region that the manority of the solar wind acceleration takes place, and where the ion compsition of the solar wind is "frozen in". This is also the region of the corona that links the surface of the Sun to the Parker Solar Probe and to Solar Orbiter. The observations suggested here would dramatically improve our understanding of solar wind formation and evolution in this critical region. Title: Recent Advances in Atmospheric, Solar-Terrestrial Physics and Space Weather From a North-South network of scientists [2006-2016] PART B : Results and Capacity Building Authors: Amory-Mazaudier, C.; Fleury, R.; Petitdidier, M.; Soula, S.; Masson, F.; Davila, J.; Doherty, P.; Elias, A.; Gadimova, S.; Makela, J.; Nava, B.; Radicella, S.; Richardson, J.; Touzani, A.; Girgea Team Bibcode: 2017SunGe..12S..21A Altcode: This paper reviews scientific advances achieved by a North-South network between 2006 and 2016. These scientific advances concern solar terrestrial physics, atmospheric physics and space weather. This part B is devoted to the results and capacity building.

Our network began in 1991, in solar terrestrial physics, by our participation in the two projects: International Equatorial Electrojet Year IEEY [1992-1993] and International Heliophysical Year IHY [2007-2009]. These two projects were mainly focused on the equatorial ionosphere in Africa.

In Atmospheric physics our research focused on gravity waves in the framework of the African Multidisciplinary Monsoon Analysis project n°1 [2005-2009 ], on hydrology in the Congo river basin and on lightning in Central Africa, the most lightning part of the world. In Vietnam the study of a broad climate data base highlighted global warming.

In space weather, our results essentially concern the impact of solar events on global navigation satellite system GNSS and on the effects of solar events on the circulation of electric currents in the earth (GIC). This research began in the framework of the international space weather initiative project ISWI [2010-2012].

Finally, all these scientific projects have enabled young scientists from the South to publish original results and to obtain positions in their countries. These projects have also crossed disciplinary boundaries and defined a more diversified education which led to the training of specialists in a specific field with knowledge of related scientific fields. Title: ASPIICS: a giant, white light and emission line coronagraph for the ESA proba-3 formation flight mission Authors: Lamy, P. L.; Vivès, S.; Curdt, W.; Damé, L.; Davila, J.; Defise, J. -M.; Fineschi, S.; Heinzel, P.; Howard, Russel; Kuzin, S.; Schmutz, W.; Tsinganos, K.; Zhukov, A. Bibcode: 2017SPIE10565E..0TL Altcode: Classical externally-occulted coronagraphs are presently limited in their performances by the distance between the external occulter and the front objective. The diffraction fringe from the occulter and the vignetted pupil which degrades the spatial resolution prevent useful observations of the white light corona inside typically 2-2.5 solar radii (Rsun). Formation flying offers and elegant solution to these limitations and allows conceiving giant, externally-occulted coronagraphs using a two-component space system with the external occulter on one spacecraft and the optical instrument on the other spacecraft at a distance of hundred meters [1, 2]. Such an instrument ASPIICS (Association de Satellites Pour l'Imagerie et l'Interférométrie de la Couronne Solaire) has been selected by the European Space Agency (ESA) to fly on its PROBA-3 mission of formation flying demonstration which is presently in phase B (Fig. 1). The classical design of an externally-occulted coronagraph is adapted to the formation flying configuration allowing the detection of the very inner corona as close as 0.04 solar radii from the solar limb. By tuning the position of the occulter spacecraft, it may even be possible to reach the chromosphere and the upper part of the spicules [3]. ASPIICS will perform (i) high spatial resolution imaging of the continuum K+F corona in photometric and polarimetric modes, (ii) high spatial resolution imaging of the E-corona in two coronal emission lines (CEL): Fe XIV and He I D3, and (iii) two-dimensional spectrophotometry of the Fe XIV emission line. ASPIICS will address the question of the coronal heating and the role of waves by characterizing propagating fluctuations (waves and turbulence) in the solar wind acceleration region and by looking for oscillations in the intensity and Doppler shift of spectral lines. The combined imaging and spectral diagnostics capabilities available with ASPIICS will allow mapping the velocity field of the corona both in the sky plane (directly on the images) and along the line-of-sight by measuring the Doppler shifts of emission lines in an effort to determine how the different components of the solar wind, slow and fast are accelerated. With a possible launch in 2014, ASPIICS will observe the corona during the maximum of solar activity, insuring the detection of many Coronal Mass Ejections (CMEs). By rapidly alternating high-resolution imaging and spectroscopy, CMEs will be thoroughly characterized. Title: Weighing supermassive black holes with the UV photon sieve space telescope Authors: Airapetian, Vladimir; Upton, Robert S.; Davila, Joseph; Marzouk, Marzouk; Carpenter, Kenneth G.; Weaver, Kimberly Bibcode: 2017SPIE10564E..3RA Altcode: The Photon Sieve Space Telescope (PSST) is a space-based ultra high-resolution (5 mas) narrow band (λ/Δλ ≃ 1000) spectral UV imager providing spectral imaging of astronomical objects in Ly - , CIV and NV emission lines. Science obtained with this telescope will revolutionize our understanding of a whole range of astrophysical processes in the local and distant universe. There will be a dramatic increase in the number of observed moderate and large SMBH masses as well as extra-solar protoplanetary disks. The observations will also enable tracing the star formation rates in active galaxies. We present the optical design, the properties and the future implementation of the proposed UV photon sieve space telescope. Title: Toward a Next Generation Solar Coronagraph: Development of a Compact Diagnostic Coronagraph on the ISS Authors: Cho, K. -S.; Bong, S. -C.; Choi, S.; Yang, H.; Kim, J.; Baek, J. -H.; Park, J.; Lim, E. -K.; Kim, R. -S.; Kim, S.; Kim, Y. -H.; Park, Y. -D.; Clarke, S. W.; Davila, J. M.; Gopalswamy, N.; Nakariakov, V. M.; Li, B.; Pinto, R. F. Bibcode: 2017JKAS...50..139C Altcode: The Korea Astronomy and Space Science Institute plans to develop a coronagraph in collaboration with National Aeronautics and Space Administration (NASA) and to install it on the International Space Station (ISS). The coronagraph is an externally occulted one-stage coronagraph with a field of view from 3 to 15 solar radii. The observation wavelength is approximately 400 nm, where strong Fraunhofer absorption lines from the photosphere experience thermal broadening and Doppler shift through scattering by coronal electrons. Photometric filter observations around this band enable the estimation of 2D electron temperature and electron velocity distribution in the corona. Together with a high time cadence (<12 min) of corona images used to determine the geometric and kinematic parameters of coronal mass ejections, the coronagraph will yield the spatial distribution of electron density by measuring the polarized brightness. For the purpose of technical demonstration, we intend to observe the total solar eclipse in August 2017 with the filter system and to perform a stratospheric balloon experiment in 2019 with the engineering model of the coronagraph. The coronagraph is planned to be installed on the ISS in 2021 for addressing a number of questions (e.g., coronal heating and solar wind acceleration) that are both fundamental and practically important in the physics of the solar corona and of the heliosphere. Title: Effects of transport coefficients on excitation of flare-induced standing slow-mode waves Authors: Wang, Tongjiang; Ofman, Leon; Davila, Joseph Bibcode: 2017SPD....48.0202W Altcode: The flare-excited longitudinal intensity oscillations in hot flaring loops have been recently detected by SDO/AIA, and interpreted as the slow-mode standing waves. By means of the seismology technique we have, for the first time, determined the transport coefficients in the hot (>9 MK) flare plasma, and found that thermal conductivity is suppressed by at least 3 times and viscosity coefficient is enhanced by a factor of 15 as the upper limit (Wang et al. 2015, ApJL, 811, L13). In this presentation, we first discuss possible causes for conduction suppression and viscosity enhancements. Then we use the nonlinear MHD simulations to validate the seismology method that is based on linear analytical analysis, and demonstrate the inversion scheme for determining transport coefficients using numerical parametric study. Finally, we show how the seismologically-determined transport coefficients are crucial for understanding the excitation of the observed standing slow-mode waves in coronal loops and the heating of the loop plasma by a footpoint flare. Title: Mission Concepts for High-Resolution Solar Imaging with a Photon Sieve Authors: Rabin, Douglas M.; Davila, Joseph; Daw, Adrian N.; Denis, Kevin L.; Novo-Gradac, Anne-Marie; Shah, Neerav; Widmyer, Thomas R. Bibcode: 2017SPD....4811006R Altcode: The best EUV coronal imagers are unable to probe the expected energy dissipation scales of the solar corona (<100 km) because conventional optics cannot be figured to near diffraction-limited accuracy at these wavelengths. Davila (2011) has proposed that a photon sieve, a diffractive imaging element similar to a Fresnel zone plate, provides a technically feasible path to the required angular resolution. We have produced photon sieves as large as 80 mm clear aperture. We discuss laboratory measurements of these devices and the path to larger apertures. The focal length of a sieve with high EUV resolution is at least 10 m. Options for solar imaging with such a sieve include a sounding rocket, a single spacecraft with a deployed boom, and two spacecraft flying in precise formation. Title: Study of the global corona evolution from the minimum to maximum of solar cycle 24 using 3D coronal electron density reconstructions with STEREO/COR1 Authors: Wang, Tongjiang; Reginald, Nelson Leslie; Davila, Joseph; St. Cyr, Orville Chris; Thompson, William T. Bibcode: 2017SPD....4830101W Altcode: This study aims at understanding the global corona evolution of the coronal activity during Solar Cycle 24 on both long-term and short-term time scales. By using a spherically symmetric polynomial approximation (SSPA) method described and validated in Wang and Davila (2014), the 3D coronal electron density in the height range of 1.5 to 3.7 Rsun is reconstructed based on STEREO/COR1-A and -B pB data. The reconstructions span a period from the Cycle 23/24 minimum to the Cycle 24 maximum, covering Carrington rotations (CRs) 2054-2153, for a total of 100 rotations. These 3D electron density distributions are validated by comparing with similar density models derived using other methods such as tomography and a MHD model as well as using data from SOHO/LASCO-C2. Uncertainties in the density reconstruction and estimated total coronal mass are analyzed. The cycle minimum-to-maximum modulation factors (MFs) of the coronal average electron density (or the total coronal mass) at different latitudinal ranges are quantified. Wavelet analysis of the cycle-long detrended density data reveals the existence of quasi-periodic short-term (7-8 months) variations during the rising and maximum activity phases. For the total mass of streamers the MFs depend on the changes in both their total area and average density, but the short-term oscillations are mainly caused by the streamer density fluctuations. A clear asymmetry is observed in the temporal evolution of the northern and southern hemispheres, with the former leading the latter by a lapse of 7-9 months, with a mild dependence on the latitude range. Title: The VUV instrument SPICE for Solar Orbiter: performance ground testing Authors: Caldwell, Martin E.; Morris, Nigel; Griffin, Douglas K.; Eccleston, Paul; Anderson, Mark; Pastor Santos, Carmen; Bruzzi, Davide; Tustain, Samuel; Howe, Chris; Davenne, Jenny; Grundy, Timothy; Speight, Roisin; Sidher, Sunil D.; Giunta, Alessandra; Fludra, Andrzej; Philippon, Anne; Auchere, Frederic; Hassler, Don; Davila, Joseph M.; Thompson, William T.; Schuehle, Udo H.; Meining, Stefan; Walls, Buddy; Phelan, P.; Dunn, Greg; Klein, Roman M.; Reichel, Thomas; Gyo, Manfred; Munro, Grant J.; Holmes, William; Doyle, Peter Bibcode: 2017SPIE10397E..08C Altcode: SPICE is an imaging spectrometer operating at vacuum ultraviolet (VUV) wavelengths, 70.4 - 79.0 nm and 97.3 - 104.9 nm. It is a facility instrument on the Solar Orbiter mission, which carries 10 science instruments in all, to make observations of the Sun's atmosphere and heliosphere, at close proximity to the Sun, i.e to 0.28 A.U. at perihelion. SPICE's role is to make VUV measurements of plasma in the solar atmosphere. SPICE is designed to achieve spectral imaging at spectral resolution >1500, spatial resolution of several arcsec, and two-dimensional FOV of 11 x16arcmins. The many strong constraints on the instrument design imposed by the mission requirements prevent the imaging performance from exceeding those of previous instruments, but by being closer to the sun there is a gain in spatial resolution. The price which is paid is the harsher environment, particularly thermal. This leads to some novel features in the design, which needed to be proven by ground test programs. These include a dichroic solar-transmitting primary mirror to dump the solar heat, a high in-flight temperature (60deg.C) and gradients in the optics box, and a bespoke variable-line-spacing grating to minimise the number of reflective components used. The tests culminate in the systemlevel test of VUV imaging performance and pointing stability. We will describe how our dedicated facility with heritage from previous solar instruments, is used to make these tests, and show the results, firstly on the Engineering Model of the optics unit, and more recently on the Flight Model. For the keywords, select up to 8 key terms for a search on your manuscript's subject. Title: Variation in Coronal Activity from Solar Cycle 24 Minimum to Maximum Using Three-Dimensional Reconstructions of the Coronal Electron Density from STEREO/COR1 Authors: Wang, Tongjiang; Reginald, Nelson L.; Davila, Joseph M.; St. Cyr, O. Chris; Thompson, William T. Bibcode: 2017SoPh..292...97W Altcode: Three-dimensional electron density distributions in the solar corona are reconstructed for 100 Carrington rotations (CR 2054 - 2153) during 2007/03 - 2014/08 using the spherically symmetric method from polarized white-light observations with the inner coronagraph (COR1) onboard the twin Solar Terrestrial Relations Observatory (STEREO). These three-dimensional electron density distributions are validated by comparison with similar density models derived using other methods such as tomography and a magnetohydrodynamics (MHD) model as well as using data from the Solar and Heliospheric Observatory (SOHO)/Large Angle and Spectrometric Coronagraph (LASCO)-C2. Uncertainties in the estimated total mass of the global corona are analyzed based on differences between the density distributions for COR1-A and -B. Long-term variations of coronal activity in terms of the global and hemispheric average electron densities (equivalent to the total coronal mass) reveal a hemispheric asymmetry during the rising phase of Solar Cycle 24, with the northern hemisphere leading the southern hemisphere by a phase shift of 7 - 9 months. Using 14 CR (≈13 -month) running averages, the amplitudes of the variation in average electron density between Cycle 24 maximum and Cycle 23/24 minimum (called the modulation factors) are found to be in the range of 1.6 - 4.3. These modulation factors are latitudinally dependent, being largest in polar regions and smallest in the equatorial region. These modulation factors also show a hemispheric asymmetry: they are somewhat larger in the southern hemisphere. The wavelet analysis shows that the short-term quasi-periodic oscillations during the rising and maximum phases of Cycle 24 have a dominant period of 7 - 8 months. In addition, it is found that the radial distribution of the mean electron density for streamers at Cycle 24 maximum is only slightly larger (by ≈30 % ) than at cycle minimum. Title: Image-optimized Coronal Magnetic Field Models Authors: Jones, Shaela I.; Uritsky, Vadim; Davila, Joseph M. Bibcode: 2017ApJ...844...93J Altcode: 2017arXiv170607316J We have reported previously on a new method we are developing for using image-based information to improve global coronal magnetic field models. In that work, we presented early tests of the method, which proved its capability to improve global models based on flawed synoptic magnetograms, given excellent constraints on the field in the model volume. In this follow-up paper, we present the results of similar tests given field constraints of a nature that could realistically be obtained from quality white-light coronagraph images of the lower corona. We pay particular attention to difficulties associated with the line-of-sight projection of features outside of the assumed coronagraph image plane and the effect on the outcome of the optimization of errors in the localization of constraints. We find that substantial improvement in the model field can be achieved with these types of constraints, even when magnetic features in the images are located outside of the image plane. Title: Variation of Coronal Activity from the Minimum to Maximum of Solar Cycle 24 using Three Dimensional Coronal Electron Density Reconstructions from STEREO/COR1 Authors: Wang, Tongjiang; Reginald, Nelson L.; Davila, Joseph M.; St. Cyr, O. Chris; Thompson, William T. Bibcode: 2017arXiv170605116W Altcode: Three dimensional electron density distributions in the solar corona are reconstructed for 100 Carrington Rotations (CR 2054$-$2153) during 2007/03$-$2014/08 using the spherically symmetric method from polarized white-light observations with the STEREO/COR1. These three-dimensional electron density distributions are validated by comparison with similar density models derived using other methods such as tomography and a MHD model as well as using data from SOHO/LASCO-C2. Uncertainties in the estimated total mass of the global corona are analyzed based on differences between the density distributions for COR1-A and -B. Long-term variations of coronal activity in terms of the global and hemispheric average electron densities (equivalent to the total coronal mass) reveal a hemispheric asymmetry during the rising phase of Solar Cycle 24, with the northern hemisphere leading the southern hemisphere by a phase shift of 7$-$9 months. Using 14-CR (~13-month) running averages, the amplitudes of the variation in average electron density between Cycle 24 maximum and Cycle 23/24 minimum (called the modulation factors) are found to be in the range of 1.6$-$4.3. These modulation factors are latitudinally dependent, being largest in polar regions and smallest in the equatorial region. These modulation factors also show a hemispheric asymmetry, being somewhat larger in the southern hemisphere. The wavelet analysis shows that the short-term quasi-periodic oscillations during the rising and maximum phases of Cycle 24 have a dominant period of 7$-$8 months. In addition, it is found that the radial distribution of mean electron density for streamers at Cycle 24 maximum is only slightly larger (by ~30%) than at cycle minimum. Title: Electron temperature maps of the low solar corona: ISCORE results from the total solar eclipse of 1 August 2008 in China Authors: Reginald, Nelson L.; Davila, Joseph M.; St. Cyr, Orville C.; Rabin, Douglas M. Bibcode: 2017JGRA..122.5856R Altcode: We conducted an experiment in conjunction with the total solar eclipse of 1 August 2008 in China to determine the thermal electron temperature in the low solar corona close to the solar limb. The instrument, Imaging Spectrograph of Coronal Electrons (ISCORE), consisted of an 8 inch f/10 Schmidt Cassegrain telescope with a thermoelectrically cooled CCD camera at the focal plane. Results are electron temperatures of 1 MK at 1.08 R and 1.13 R from the Sun center in the polar and equatorial regions, respectively. This experiment confirms the results of an earlier experiment conducted in conjunction with the total eclipse of 29 March 2006 in Libya, and results are that at a given coronal height the electron temperature in the polar region is larger than at the equatorial region. In this paper we show the importance of using the correct photospheric spectrum pertinent to the solar activity phase at the time of the experiment, which is a required parameter for modeling the underlying theoretical concept for temperature interpretation of the measured intensity ratios using color filters. Title: Image-Optimized Coronal Magnetic Field Models Authors: Jones, S. I.; Davila, J. M.; Uritsky, V. M. Bibcode: 2016AGUFMSH43A2555J Altcode: Synoptic photospheric magnetograms suffer from a number of known issues; the evolution of the magnetic field on the far side of the sun being one of them. These issues are important because photospheric maps are often used as boundary conditions for models of the coronal magnetic field, and choices made during the construction of the maps can have a large effect on the resulting model. We have developed a method for quantifying the agreement between coronal magnetic field models and coronagraph images, which we use to strategically perturb the underlying magnetogram until an optimal agreement between the model and the images is achieved. Here we present a theoretical test of our method, and results of our first application of the method using MLSO K-Cor images. Title: Determination of transport coefficients from flare-excited standing slow-mode waves observed by SDO/AIA Authors: Wang; Tongjiang; Ofman, Leon; Davila, Joseph M. Bibcode: 2016usc..confE..36W Altcode: The flare-excited longitudinal intensity oscillations in hot flaring loops have been recently detected by SDO/AIA in 94 and 131 Angstrom bandpasses. These oscillations show similar physical properties (such as period, decay time, and trigger) as the Doppler shift oscillations previously detected by the SOHO/SUMER spectrometer in flare lines formed above 6 MK, which were mostly interpreted as the slow-mode standing waves. By applying the coronal seismology method we have, for the first time, found quantitative evidence of thermal conduction suppression in a hot (>9 MK) flare-heated loop with SDO/AIA (Wang et al. 2015, ApJL, 811, L13). This result has significant implications in two aspects. The first aspect is that the conduction suppression suggests the need of greatly enhanced compressive viscosity to interpret the observed strong wave damping. The second aspect is that the conduction suppression provides a reasonable mechanism for explaining the long-duration events where the hot plasma detected in X-rays or EUV in many flares cools much slower than expected from the classical Spitzer conductive cooling. In this presentation, we first review the observational results of the event, and then discuss possible causes for conduction suppression and viscosity enhancements. In addition, we will use the nonlinear MHD simulations to validate the seismology method that is based on linear analytical analysis, and demonstrate the inversion scheme for determining transport coefficients using numerical parametric study. Finally, as an application of our analysis, we will demonstrate how the observationally-constrained transport coefficients are crucial in providing a self-consistent explanation for the rapid excitation of standing slow-mode waves in a coronal loop by a footpoint flare. Title: Evolution of 3D electron density of the solar corona from the minimum to maximum of Solar Cycle 24 Authors: Wang, Tongjiang; Reginald, Nelson L.; Davila, Joseph M.; St Cyr, O. C. Bibcode: 2016usc..confE..53W Altcode: The variability of the solar white-light corona and its connection to the solar activity has been studied for more than a half century. It is widely accepted that the temporal variation of the total radiance of the K-corona follows the solar cycle pattern (e.g., correlated with sunspot number). However, the origin of this variation and its relationships with regard to coronal mass ejections and the solar wind are yet to be clearly understood. COR1-A and -B instruments onboard the STEREO spacecraft have continued to perform high-cadence (5 min) polarized brightness (pB) measurements from two different vantage points from the solar minimum to the solar maximum of Solar Cycle 24. With these pB observations we have reconstructed the 3D coronal density between 1.5-4.0 solar radii for 100 Carrington rotations (CRs) from 2007 to 2014 using the spherically symmetric inversion (SSI) method. We validate these 3D density reconstructions by other means such as tomography, MHD modeling, and pB inversion of LASCO/C2 data. We analyze the solar cycle variations of total coronal mass (or average density) over the global Sun and in two hemispheres, as well as the variations of the streamer area and mean density. We find the short-term oscillations of 8-9 CRs during the ascending and maximum phases through wavelet analysis. We explore the origin of these oscillations based on evolution of the photospheric magnetic flux and coronal structures. 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: 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: Computational image formation with photon sieves for milli-arcsecond solar imaging Authors: Oktem, Figen S.; Kamalabadi, Farzad; Davila, Joseph Bibcode: 2016cosp...41E1465O Altcode: A photon sieve is a modification of a Fresnel zone plate in which open zones are replaced by a large number of circular holes. This diffractive imaging element is specially suited to observations at UV and x-ray wavelengths where refractive lenses are not available due to strong absorption of materials, and reflective mirrors are difficult to manufacture with sufficient surface figure accuracy to achieve diffraction-limited resolution. On the other hand, photon sieves enable diffraction-limited imaging with much more relaxed tolerances than conventional imaging technology. In this presentation, we present the capabilities of an instrument concept that is based on computational image formation with photon sieves. The instrument enables high-resolution spectral imaging by distributing the imaging task between a photon sieve system and a computational method. A photon sieve coupled with a moving detector provides measurements from multiple planes. Then computational image formation, which involves deconvolution, is performed in a Bayesian estimation framework to reconstruct the multi-spectral images from these measurements. In addition to diffraction-limited high spatial resolution enabled by photon sieves, this instrument can also achieve higher spectral resolution than the conventional spectral imagers, since the technique offers the possibility of separating nearby spectral components that would not otherwise be possible using wavelength filters. Here, the promising capabilities and the imaging performance are shown for imaging the solar corona at EUV wavelengths. The effectiveness of various potential observing scenarios, the effects of interfering emission lines, and the appropriate form of the cost function for image deconvolution are examined. Title: Milli-Arcsecond Imaging of the Solar Corona Authors: Davila, Joseph; Kamalabadi, Farzad; Oktem, Figen S. Bibcode: 2016cosp...41E.407D Altcode: Dissipation in the solar corona is believed to occur in extremely thin current sheets of order 1-100 km. Emission from these hot but thin current sheets is visible in coronal EUV emission lines, however, this spatial scale is unresolved in existing imaging instruments. Conventional optics cannot be easily manufactured with sufficient surface figure accuracy to obtain the required resolution. A photon sieve, a diffractive imaging element similar to a Fresnel zone plate, can be manufactured to provide a few milli-arcsec (mas) resolution, with much more relaxed tolerances than conventional imaging technology. Images from photon sieves will not only show the structure of the corona at a resolution never before obtained, they will also allow a study of the temperature structure in the dissipation region. Several photon sieves have been designed, fabricated, and tested by us at Goddard Space Flight Center. To fully exploit the potential of these devices two new technologies, (1) formation flying and (2) computational image deconvolution must be used. Recent progress on photon sieve development as well as these issues will be discussed. A simple design for a sounding rocket payload is presented that obtains 80 mas (0.080 arcsec) imaging with a 100 mm diameter photon sieve to image Fe XIV 334 and Fe XVI 335 which would provide a demonstration of this technology. Title: Coronal Seismology of Flare-Excited Standing Slow-Mode Waves Observed by SDO/AIA Authors: Wang, Tongjiang; Ofman, Leon; Davila, Joseph M. Bibcode: 2016SPD....47.0632W Altcode: Flare-excited longitudinal intensity oscillations in hot flaring loops have been recently detected by SDO/AIA in 94 and 131 Å bandpasses. Based on the interpretation in terms of a slow-mode wave, quantitative evidence of thermal conduction suppression in hot (>9 MK) loops has been obtained for the first time from measurements of the polytropic index and phase shift between the temperature and density perturbations (Wang et al. 2015, ApJL, 811, L13). This result has significant implications in two aspects. One is that the thermal conduction suppression suggests the need of greatly enhanced compressive viscosity to interpret the observed strong wave damping. The other is that the conduction suppression provides a reasonable mechanism for explaining the long-duration events where the thermal plasma is sustained well beyond the duration of impulsive hard X-ray bursts in many flares, for a time much longer than expected by the classical Spitzer conductive cooling. In this study, we model the observed standing slow-mode wave in Wang et al. (2015) using a 1D nonlinear MHD code. With the seismology-derived transport coefficients for thermal conduction and compressive viscosity, we successfully simulate the oscillation period and damping time of the observed waves. Based on the parametric study of the effect of thermal conduction suppression and viscosity enhancement on the observables, we discuss the inversion scheme for determining the energy transport coefficients by coronal seismology. Title: Formation Flying Spacecraft Concept for Heliophysics Applications Authors: Novo-Gradac, Anne-Marie; Davila, Joseph; Yang, Guangning; Lu, Wei; Shah, Neerav; Li, Steven X. Bibcode: 2016SPD....4720603N Altcode: A number of space-based heliophysics instruments would benefit from formation flying spacecraft. An occulter or a focusing optic such as a photon sieve could be mounted on a separate spacecraft rather than at the end of a boom. This would enable science measurements to be made on smaller, less expensive spacecraft. To accomplish this goal, the relative position of the spacecraft must be monitored and controlled to high precision. We describe two separate optical sensing systems that monitor relative position of the spacecraft to the level required for a photon sieve mission concept wherein the photon sieve is mounted on one spacecraft while the imaging detector is mounted on another. The first system employs a novel time of flight measurement of a laser beam that includes imbedded optical data packets. The contents of the returning data packet can be compared to the departing data packet to provide an extremely high resolution distance measurement. Employing three such systems allows measurement of pitch and yaw in addition to longitudinal separation. The second optical system monitors lateral motion. A mildy divergent laser beam is transmitted from one spacecraft to a sensor array on the second spacecraft. Monitoring the position of the brightest portion of the beam on the sensor array provides a direct measurement of lateral relative motion. Employing at least two such systems enables monitoring roll of the spacecraft as well as centration. We will also discuss low force thruster systems required for high precision station keeping. Title: Milli-Arcsecond (MAS) Imaging of the Solar Corona Authors: Davila, Joseph M.; Oktem, Figen S.; Kamalabadi, Farzad; O'Neill, John; Novo-Gradac, Anne-Marie; Daw, Adrian N.; Rabin, Douglas M. Bibcode: 2016SPD....47.0310D Altcode: Dissipation in the solar corona is believed to occur in extremely thin current sheets of order 1-100 km. Emission from these hot but thin current sheets should be visible in coronal EUV emission lines. However, this spatial scale is far below the resolution of existing imaging instruments, so these dissipation sites have never been observed individually. Conventional optics cannot be manufactured with sufficient surface figure accuracy to obtain the required spatial resolution in the extreme-ultraviolet where these hot plasmas radiate. A photon sieve, a diffractive imaging element similar to a Fresnel zone plate, can be manufactured to provide a few milli-arcsec (MAS) resolution, with much more readily achievable tolerances than with conventional imaging technology. Prototype photon sieve elements have been fabricated and tested in the laboratory. A full-scale ultra-high resolution instrument will require formation flying and computational image deconvolution. Significant progress has been made in overcoming these challenges, and some recent results in these areas are discussed. A simple design for a sounding rocket concept demonstration payload is presented that obtains 80 MAS (0.080 arcsec) imaging with a 100 mm diameter photon sieve to image Fe XIV 334 and Fe XVI 335. These images will show the structure of the corona at a resolution never before obtained, and they will also allow a study of the temperature structure in the dissipation region. Title: 3D Distribution of the Coronal Electron Density and its Evolution with Solar Cycle Authors: Wang, Tongjiang; Reginald, Nelson Leslie; Davila, Joseph M.; St. Cyr, Orville Chris Bibcode: 2016SPD....47.0337W Altcode: The variability of the solar white-light corona and its connection to the solar activity has been studied for more than a half century. It is widely accepted that the temporal variation of the total radiance of the K-corona follows the solar cycle pattern (e.g., correlated with sunspot number). However, the origin of this variation and its relationships with regard to coronal mass ejections and the solar wind are yet to be clearly understood. We know that the COR1-A and -B instruments onboard the STEREO spacecraft have continued to perform high-cadence (5 min) polarized brightness measurements from two different vantage points over a long period of time that encompasses the solar minimum of Solar Cycle 23 to the solar maximum of Solar Cycle 24. This extended period of polarized brightness measurements can now be used to reconstruct 3D electron density distributions of the corona between the heliocentric heights of 1.5-4.0 solar radii. In this study we have constructed the 3D coronal density models for 100 Carrington rotations (CRs) from 2007 to 2014 using the spherically symmetric inversion (SSI) method. The validity of these 3D density models is verified by comparing with similar 3D density models created by other means such as tomography, MHD modeling, and 2D density distributions inverted from the polarized brightness images from LASCO/C2 instrument onboard the SOHO spacecraft. When examining the causes for the temporal variation of the global electron content we find that its increase from the solar minimum to maximum depends on changes to both the total area and mean density of coronal streamers. We also find that the global and hemispheric electron contents show quasi-periodic variations with a period of 8-9 CRs during the ascending and maximum phases of Solar Cycle 24 through wavelet analysis. In addition, we also explore any obvious relationships between temporal variation of the global electron content with the photospheric magnetic flux, total mass of CMEs and CME occurrence rate. Title: Optimizing Global Coronal Magnetic Field Models Using Image-based Constraints Authors: Jones, Shaela I.; Davila, Joseph M.; Uritsky, Vadim Bibcode: 2016ApJ...820..113J Altcode: 2015arXiv151103994J The coronal magnetic field directly or indirectly affects a majority of the phenomena studied in the heliosphere. It provides energy for coronal heating, controls the release of coronal mass ejections, and drives heliospheric and magnetospheric activity, yet the coronal magnetic field itself has proven difficult to measure. This difficulty has prompted a decades-long effort to develop accurate, timely, models of the field—an effort that continues today. We have developed a method for improving global coronal magnetic field models by incorporating the type of morphological constraints that could be derived from coronal images. Here we report promising initial tests of this approach on two theoretical problems, and discuss opportunities for application. Title: Evidence of thermal conduction suppression in hot coronal loops: supplementary results Authors: Wang, Tongjiang; Ofman, Leon; Sun, Xudong; Provornikova, Elena; Davila, Joseph M. Bibcode: 2016IAUS..320..202W Altcode: 2015arXiv151002750W Slow magnetoacoustic waves were first detected in hot (>6 MK) flare loops by the SOHO/SUMER spectrometer as Doppler shift oscillations in Fe xix and Fe xxi lines. Recently, such longitudinal waves have been found by SDO/AIA in the 94 and 131 Å channels. Wang et al. (2015) reported the first AIA event revealing signatures in agreement with a fundamental standing slow-mode wave, and found quantitative evidence for thermal conduction suppression from the temperature and density perturbations in the hot loop plasma of >~ 9 MK. The present study extends the work of Wang et al. (2015) by using an alternative approach. We determine the polytropic index directly based on the polytropic assumption instead of invoking the linear approximation. The same results are obtained as in the linear approximation, indicating that the nonlinearity effect is negligible. We find that the flare loop cools slower (by a factor of 2-4) than expected from the classical Spitzer conductive cooling, approximately consistent with the result of conduction suppression obtained from the wave analysis. The modified Spitzer cooling timescales based on the nonlocal conduction approximation are consistent with the observed, suggesting that nonlocal conduction may account for the observed conduction suppression in this event. In addition, the conduction suppression mechanism predicts that larger flares may tend to be hotter than expected by the EM-T relation derived by Shibata & Yokoyama (2002). Title: Performance Measurements of the Flight Detector for SPICE on SolarOrbiter Authors: Thompson, W. T.; Davila, J. M.; Caldwell, M.; Siegmund, O. Bibcode: 2015AGUFMSH31C2431T Altcode: The Spectral Imaging of the Coronal Environment (SPICE) instrument for theSolar Orbiter mission will make spectroscopic observations of the Sun's lowcorona to characterize the plasma properties of the source regions of the solarwind. The detector package for SPICE, provided by the NASA Goddard SpaceFLight Center, consists of two microchannel-plate (MCP) intensified ActivePixel Sensor (APS) detectors covering the short (702-792 Angstroms) and long(972-1050 Angstroms) wavelength bandpasses. The long wavelength detector willalso provide coverage in second order between 485-525 Angstroms. We previouslyreported on measurements of the engineering model detector. Here, we report onmeasurements made on the flight SPICE detector in the same vacuum tank facilityat the Rutherford Appleton Laboratory in Harwell, UK. These measurementsinclude the detector flat field, sensitivity, resolution, linearity, andstatistical noise. A krypton resonance lamp operating at 1236 Angstroms wasused to stimulate the detector. Results at this wavelength are combined withthe quantum efficiency measurements of the individual MCPs at this and otherwavelengths covering the entire wavelength range to provide a completecalibration curve for the instrument. A calibrated NIST photodiode was used todetermine the absolute brightness of the lamp. Title: Coronal seismology of flare-excited longitudinal slow magnetoacoustic waves in hot coronal loops Authors: Wang, T.; Ofman, L.; Sun, X.; Provornikova, E. A.; Davila, J. M. Bibcode: 2015AGUFMSH13B2435W Altcode: The flare-excited longitudinal intensity oscillations in hot flaring loops have been recently detected by SDO/AIA in 94 and 131 bandpasses. These oscillations show similar physical properties (such as period, decay time, and trigger) as those slow-mode standing waves previously detected by the SOHO/SUMER spectrometer in Doppler shift of flare lines formed above 6 MK. The multi-wavelength AIA observations with high spatio-temporal resolution and wide temperature coverage enable us to measure both thermal and wave properties of the oscillating hot plasma with unprecedented accuracy. These new measurements can be used to diagnose the complicated energy transport processes in flare plasma by a technique called coronal seismology based on the combination of observations and MHD wave theory. From a detailed case study we have found evidence for thermal conduction suppression in hot loops by measuring the polytropic index and analyzing the phase relationship between the temperature and density wave signals. This result is not only crucial for better understanding the wave dissipation mechanism but also provides an alternative mechanism to explain the puzzles of long-duration events and X-ray loop-top sources which show much slower cooling than expected by the classical Spitzer conductive cooling. This finding may also shed a light on the coronal heating problem because weak thermal conductivity implies slower cooling of hot plasma in nanoflares, so increasing the average coronal temperature for the same heating rate. We will discuss the effects of thermal conduction suppression on the wave damping and loop cooling based on MHD simulations. Title: Improving Heliospheric Field Models with Optimized Coronal Models Authors: Jones, S. I.; Davila, J. M.; Uritsky, V. M. Bibcode: 2015AGUFMSH31C2443J Altcode: The Solar Orbiter and Solar Probe Plus missions will travel closer to the sun than any previous mission, collecting unprecedented in situ data. This data can provide insight into coronal structure, energy transport, and evolution in the inner heliosphere. However, in order to take full advantage of this data, researchers need quality models of the inner heliosphere to connect the in situ observations to their coronal and photospheric sources. Developing quality models for this region of space has proved difficult, in part because the only part of the field that is accessible for routine measurement is the photosphere. The photospheric field measurements, though somewhat problematic, are used as boundary conditions for coronal models, which often neglect or over-simplify chromospheric conditions, and these coronal models are then used as boundary conditions to drive heliospheric models. The result is a great deal of uncertainty about the accuracy and reliability of the heliospheric models. Here we present a technique we are developing for improving global coronal magnetic field models by optimizing the models to conform to the field morphology observed in coronal images. This agreement between the coronal model and the basic morphology of the corona is essential for creating accurate heliospheric models. We will present results of early tests of two implementations of this idea, and its first application to real-world data. Title: Measuring Physical Parameters of CMES Authors: Reginald, N. L.; Davila, J. M.; St Cyr, O. C. Bibcode: 2015AGUFMSH21B2405R Altcode: In earlier work using eclipse observations, we have demonstrated that coronal electron density, electron temperature and their bulk flow speed can be measured. We have recently extended the associated modeling to include the passage of a CME, and we describe the preliminary results. The electron temperature in the solar corona determines the amount of Doppler broadening of the solar spectrum as it Thomson scatters off the coronal electrons. The outward flow of the coronal electrons from the solar surface causes the coronal electrons to see a red-shifted Sun and determines the amount of red-shift in the K-coronal spectrum. Thus, the intensity, smoothness and red-shift of the K-coronal spectrum along any given line of sight provide a measure of the electron density, electron temperature and electron bulk flow speed, respectively, along that line of sight. Likewise, the passing of a CME across a line of sight in the ambient corona will alter the shape of the K-coronal spectrum with respect to the ambient background. Title: Constraining Large-Scale Solar Magnetic Field Models with Optical Coronal Observations Authors: Uritsky, V. M.; Davila, J. M.; Jones, S. I. Bibcode: 2015AGUFMSH31C2444U Altcode: Scientific success of the Solar Probe Plus (SPP) and Solar Orbiter (SO) missions will depend to a large extent on the accuracy of the available coronal magnetic field models describing the connectivity of plasma disturbances in the inner heliosphere with their source regions. We argue that ground based and satellite coronagraph images can provide robust geometric constraints for the next generation of improved coronal magnetic field extrapolation models. In contrast to the previously proposed loop segmentation codes designed for detecting compact closed-field structures above solar active regions, we focus on the large-scale geometry of the open-field coronal regions located at significant radial distances from the solar surface. Details on the new feature detection algorithms will be presented. By applying the developed image processing methodology to high-resolution Mauna Loa Solar Observatory images, we perform an optimized 3D B-line tracing for a full Carrington rotation using the magnetic field extrapolation code presented in a companion talk by S.Jones at al. Tracing results are shown to be in a good qualitative agreement with the large-scalie configuration of the optical corona. Subsequent phases of the project and the related data products for SSP and SO missions as wwll as the supporting global heliospheric simulations will be discussed. 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: Evidence of Thermal Conduction Suppression in a Solar Flaring Loop by Coronal Seismology of Slow-mode Waves Authors: Wang, Tongjiang; Ofman, Leon; Sun, Xudong; Provornikova, Elena; Davila, Joseph M. Bibcode: 2015ApJ...811L..13W Altcode: 2015arXiv150900920W Analysis of a longitudinal wave event observed by the Atmospheric Imaging Assembly (AIA) onboard the Solar Dynamics Observatory is presented. A time sequence of 131 Å images reveals that a C-class flare occurred at one footpoint of a large loop and triggered an intensity disturbance (enhancement) propagating along it. The spatial features and temporal evolution suggest that a fundamental standing slow-mode wave could be set up quickly after meeting of two initial disturbances from the opposite footpoints. The oscillations have a period of ∼12 minutes and a decay time of ∼9 minutes. The measured phase speed of 500 ± 50 km s-1 matches the sound speed in the heated loop of ∼10 MK, confirming that the observed waves are of slow mode. We derive the time-dependent temperature and electron density wave signals from six AIA extreme-ultraviolet channels, and find that they are nearly in phase. The measured polytropic index from the temperature and density perturbations is 1.64 ± 0.08 close to the adiabatic index of 5/3 for an ideal monatomic gas. The interpretation based on a 1D linear MHD model suggests that the thermal conductivity is suppressed by at least a factor of 3 in the hot flare loop at 9 MK and above. The viscosity coefficient is determined by coronal seismology from the observed wave when only considering the compressive viscosity dissipation. We find that to interpret the rapid wave damping, the classical compressive viscosity coefficient needs to be enhanced by a factor of 15 as the upper limit. Title: Evidence of thermal conduction depression in hot coronal loops Authors: Wang, Tongjiang; Ofman, Leon; Sun, Xudong; Provornikova, Elena; Davila, Joseph Bibcode: 2015IAUGA..2257766W Altcode: Slow magnetoacoustic waves were first detected in hot (>6 MK) flare loops by the SOHO/SUMER spectrometer as Doppler shift oscillations in Fe XIX and Fe XXI lines. These oscillations are identified as standing slow-mode waves because the estimated phase speeds are close to the sound speed in the loop and some cases show a quarter period phase shift between velocity and intensity oscillations. The observed very rapid excitation and damping of standing slow mode waves have been studied by many authors using theories and numerical simulations, however, the exact mechanisms remain not well understood. Recently, flare-induced longitudinal intensity oscillations in hot post-flare loops have been detected by SDO/AIA. These oscillations have the similar physical properties as SUMER loop oscillations, and have been interpreted as the slow-mode waves. The multi-wavelength AIA observations with high spatio-temporal resolution and wide temperature coverage allow us to explore the wave excitation and damping mechanisms with an unprecedented detail to develope new coronal seismology. In this paper, we present accurate measurements of the effective adiabatic index (γeff) in the hot plasma from the electron temperature and density wave signals of a flare-induced longitudinal wave event using SDO/AIA data. Our results strikingly and clearly reveal that thermal conduction is highly depressed in hot (∼10 MK) post-flare loops and suggest that the compressive viscosity is the dominant wave damping mechanism which allows determination of the viscosity coefficient from the observables by coronal seismology. This new finding challenges our current understanding of thermal energy transport in solar and stellar flares, and may provide an alternative explanation of long-duration events and enhance our understand of coronal heating mechanism. We will discuss our results based on non-ideal MHD theory and simulations. We will also discuss the flare trigger mechanism based on magnetic topology derived from SDO/HMI vector magnetic fields using nonlinear force-free field extrapolations and discuss the wave excitation mechanism based on 3D MHD modeling of the active region. Title: Variations of the Electron Density of Coronal Streamers with Solar Cycle Observed with STEREO/COR1 Authors: Wang, Tongjiang; Reginald, Nelson; Davila, Joseph M. Bibcode: 2015IAUGA..2258408W Altcode: The temporal variations of the total or integrated radiance of the K-corona of the Sun were found to be correlated with solar activity (or sunspot) cycle in some previous studies. In this paper, we address the question on how the global electron content of the corona varies with the solar cycle, and relates to the evolution of photospheric magnetic flux and CME mass during Solar Cycle 23/24. We reconstructed the 3D coronal density from STEREO/COR1 pB images by using a spherically symmetric polynomial approximation (SSPA) method. The comparisons show that the SSPA 3D density is consistent well with that obtained by tomography inversion or by the 3D MHD model. We find that the total mass of the corona (mainly from streamers) within 1.5-3.7 solar radius reached a minimum at solar minimum near 2009 and then stayed stable until 2010 when the solar activity started to again increase. The coronal mass increased by a factor of about 2 during 2010-2014, compared to the minimum period and exhibited strong variations. We find that the variations of total streamer mass are highly correlated with those of total unsigned magnetic flux measured on the photosphere. In addition, we also find there is a high correlation between the total coronal mass and the average mass of CMEs as well as the CME occurrence rate. We will compare the radial electron density distribution between the streamers during the solar minimum and solar maximum periods, and discuss their implication for origin of the slow solar winds. We will also discuss the origin of coronal mass content in streamers based on 3D MHD modeling. Title: Optimization of Coronal Magnetic Field Extrapolations Using Images Authors: Jones, Shaela; Davila, Joseph M.; Uritsky, Vadim M. Bibcode: 2015TESS....120103J Altcode: The coronal magnetic field plays a significant role in every major question we have asked about the corona, as well as about other systems and bodies throughout the heliosphere. Knowledge of the magnetic field is essential for understanding and predicting many phenomena. Despite its importance, the coronal magnetic field is not well measured, due to the tenuous nature of the coronal plasma. In the absence of reliable coronal measurements, solar physicists have developed many methods for extrapolating the photospheric magnetic field out into the corona. However, these extrapolation methods must incorporate many assumptions, and it has been shown that they do not always match observed coronal features well.Here we present a new method we are developing for altering an extrapolated magnetic field to better agree with features identified in coronal images. Our method proceeds by iteratively altering the boundary condition (the photospheric magnetogram) and comparing the extrapolated field to features observed in coronal images until optimal agreement is reached. This technique can be used in combination with any extrapolation method, depending on computational capabilities. By comparing the extrapolations with coronagraph images (see related submission by Uritsky et al.), it will be possible to improve determination of sources of open flux in the inner heliosphere. Title: Turbulent photospheric drivers of multiscale solar corona Authors: Uritsky, Vadim M.; Ofman, Leon; Davila, Joseph M. Bibcode: 2015TESS....121305U Altcode: We investigate the collective dynamics of transient photospheric and coronal events detected using high-resolution solar magnetograms and coronal emission images. We focus on statistical, ensemble-averaged properties of the interacting solar regions [Uritsky et al., 2011, 2013, 2014; Uritsky and Davila, 2012], as opposed to case-oriented methodologies recruited in some previous studies. The behavior of solar events is studied in the three-dimensional space-time enabling accurate representation of the event evolution. By applying advanced data analysis methods including feature tracking algorithms, multiscale correlation analysis and scaling analysis techniques, we identify leading physical scenarios of the photosphere - corona coupling in quiet and active solar regions, and strive to identify new statistical precursors of coronal eruptions. We also discuss the possibility of modeling multiscale photosphere - corona interactions using idealized three-dimensional MHD models. The obtained results shed a new light on the origin of multiscale dissipation in the solar corona by enabling quantitative validation of several popular statistical physical scenarios, such as e.g. intermittent turbulence, self-organized criticality, and topological complexity. Title: Reconstructing the open-field magnetic geometry of solar corona using coronagraph images Authors: Uritsky, Vadim M.; Davila, Joseph M.; Jones, Shaela; Burkepile, Joan Bibcode: 2015TESS....120106U Altcode: The upcoming Solar Probe Plus and Solar Orbiter missions will provide an new insight into the inner heliosphere magnetically connected with the topologically complex and eruptive solar corona. Physical interpretation of these observations will be dependent on the accurate reconstruction of the large-scale coronal magnetic field. We argue that such reconstruction can be performed using photospheric extrapolation codes constrained by white-light coronagraph images. The field extrapolation component of this project is featured in a related presentation by S. Jones et al. Here, we focus on our image-processing algorithms conducting an automated segmentation of coronal loop structures. In contrast to the previously proposed segmentation codes designed for detecting small-scale closed loops in the vicinity of active regions, our technique focuses on the large-scale geometry of the open-field coronal features observed at significant radial distances from the solar surface. Coronagraph images are transformed into a polar coordinate system and undergo radial detrending and initial noise reduction followed by an adaptive angular differentiation. An adjustable threshold is applied to identify candidate coronagraph features associated with the large-scale coronal field. A blob detection algorithm is used to identify valid features against a noisy background. The extracted coronal features are used to derive empirical directional constraints for magnetic field extrapolation procedures based on photospheric magnetograms. Two versions of the method optimized for processing ground-based (Mauna Loa Solar Observatory) and satellite-based (STEREO Cor1 and Cor2) coronagraph images are being developed. Title: Spectroscopic Diagnosis of Propagating disturbances in coronal loops: Waves or flows? Authors: Wang, Tongjiang; Ofman, Leon; Davila, Joseph M. Bibcode: 2015arXiv150104082W Altcode: The analysis of multiwavelength properties of propagating disturbances (PDs) using Hinode/EIS observations is presented. Quasi-periodic PDs were mostly interpreted as slow magnetoacoustic waves in early studies, but recently suggested to be intermittent upflows of the order of 50-150 km/s based on the Red-Blue (RB) asymmetry analysis of spectral line profiles. Using the forward models, velocities of the secondary component derived from the RB analysis are found significantly overestimated due to the saturation effect when its offset velocities are smaller than the Gaussian width. We developed a different method to examine spectral features of the PDs. This method is assuming that the excessive emission of the PD profile against the background (taken as that prior to the PD) is caused by a hypothetic upflow. The derived LOS velocities of the flow are on the order of 10-30 km/s from the warm (1-1.5 MK) coronal lines, much smaller than those inferred from the RB analysis. This result does not support the flow interpretation but favors of the early wave interpretation. Title: New Approaches to Externally Occulted Coronagraphs Authors: Rabin, D. M.; Chamberlin, P. C.; Davila, J. M.; Shah, N. Bibcode: 2014AGUFMSH53B4226R Altcode: The rapidly advancing capabilities of low-cost space platforms prompts us to reconsider concepts for externally occulted solar coronagraphs. Placing the occulter on a separate platform offers superior diffraction control but requires an analysis of alignment and separation tolerances that is different from that applied to conventional architectures. New forms of occulter (e.g., an inflatable sphere or ellipsoid) have potential advantages such as low mass and fabrication cost, simple deployment, and less stringent demands on the relative alignment of the platforms. However, the diffraction behavior of occulters that incorporate curved surfaces (Buffington 2000) is less explored than for edge-type occulters. We illustrate the new possibilities by calculating the performance of some candidate systems using an analytic framework adapted from radio wave propagation (Vogler 1985) and alignment tolerances based on a recent concept for a two-platform guidance, navigation, and control system. Title: Exploring the Photon Sieve: Mathematical Framework and Experimental Categorization Authors: O'Neill, J. F., Jr.; Davila, J. M.; Oktem, F.; Daw, A. N. Bibcode: 2014AGUFMSH53B4234O Altcode: The photon sieve is a diffractive optical element similar to a Fresnel zone plate, however instead of alternating rings of opaque and transmissive material the sieve is made up of many holes arranged in concentric circles. A sieve provides diffraction-limited resolution where traditional reflective and refractive optics are unable to, such as in the extreme ultraviolet. We present here recent results of testing the photon sieve's properties and comparing them to theory. Such results include multiple wavelengths, point spread function analysis, and off axis imaging. We also investigate the case in which there are multiple solar spectral lines near the sieve's depth of focus. The image observed will be a combination of multiple distinct spectral lines with different intrinsic blurs. Separating these lines is mathematically similar to an inverse problem we developed for slitless spectroscopy and is considered within this same framework. Title: Automated tracing of open-field coronal structures for an optimized large-scale magnetic field reconstruction Authors: Uritsky, V. M.; Davila, J. M.; Jones, S. I. Bibcode: 2014AGUFMSH21B4108U Altcode: Solar Probe Plus and Solar Orbiter will provide detailed measurements in the inner heliosphere magnetically connected with the topologically complex and eruptive solar corona. Interpretation of these measurements will require accurate reconstruction of the large-scale coronal magnetic field. In a related presentation by S. Jones et al., we argue that such reconstruction can be performed using photospheric extrapolation methods constrained by white-light coronagraph images. Here, we present the image-processing component of this project dealing with an automated segmentation of fan-like coronal loop structures. In contrast to the existing segmentation codes designed for detecting small-scale closed loops in the vicinity of active regions, we focus on the large-scale geometry of the open-field coronal features observed at significant radial distances from the solar surface. The coronagraph images used for the loop segmentation are transformed into a polar coordinate system and undergo radial detrending and initial noise reduction. The preprocessed images are subject to an adaptive second order differentiation combining radial and azimuthal directions. An adjustable thresholding technique is applied to identify candidate coronagraph features associated with the large-scale coronal field. A blob detection algorithm is used to extract valid features and discard noisy data pixels. The obtained features are interpolated using higher-order polynomials which are used to derive empirical directional constraints for magnetic field extrapolation procedures based on photospheric magnetograms. Title: Slitless Spectroscopy: Inverse Solutions With Overlapping Lines Authors: Davila, J. M.; O'Neill, J. F., Jr. Bibcode: 2014AGUFMSH53B4216D Altcode: Spectrometers provide our most detailed diagnostics of the solar coronal plasma, and spectral data is routinely used to measure the temperature, density, and flow velocity in coronal features. However spectrographs suffer from a limited instantaneous field-of-view (IFOV), and imaging instruments, on the other hand, can provide a relatively large IFOV but offer only very limited spectral resolution. In previous work, synthetic data was produced which had spectral properties derived from the observations of the Hinode/EIS spectrometer. We assumed observations in multiple spectral orders, then used an inverse problem method to infer the spectral properties of the solar source. Physical constraints and regularization derived from prior knowledge were incorporated as part of the solution process. However in previous work a single emission line without overlapping from neighboring lines was assumed. In this paper we present solutions of a more realistic case solving for spectral line intensity, Doppler shift, and Gaussian width in the case where overlapping lines are present. Title: High-Resolution Solar Imaging With Photon Sieves Authors: Oktem, F. S.; Kamalabadi, F.; Davila, J. M. Bibcode: 2014AGUFMSH53B4219O Altcode: A photon sieve is a modification of a Fresnel zone plate in which open zones are replaced by a large number of circular holes. This lightweight optical device offers a superior image forming capability compared with the Fresnel zone plate, and is specially suited to observations at UV and x-ray wavelengths where refractive lenses are not available due to strong absorption of materials, and reflective mirrors are difficult to manufacture to achieve near diffraction-limited resolution. At these shorter wavelengths, photon sieves enable diffraction-limited imaging performance with relaxed manufacturing tolerances, and simple and low-cost fabrication. In this work, we present a new photon sieve imaging modality that, unlike previous designs, takes advantage of chromatic aberration. The fact that different wavelengths are focused at different distances from photon sieve is exploited to develop a novel multi-spectral imaging technique. The idea is to use a photon sieve imaging system with a moving detector which records images at different planes. Each measurement consists of superimposed images of different wavelengths, with each individual image being either in focus or out of focus. For spatially incoherent illumination, we study the problem of recovering the individual images from these superimposed measurements. We first formulate the discrete forward problem using the closed-form Fresnel imaging formulas. The inverse problem is then a multi-frame deconvolution problem involving multiple objects, and is formulated as a maximum posterior estimation problem. The resulting nonlinear optimization problem is solved using a fixed-point iterative algorithm. In contrast to traditional spectral imagers employing a series of wavelength filters, the proposed technique relies on a simple optical system, but incorporates powerful image processing methods to form spectral images computationally. In addition to diffraction-limited high spatial resolution enabled by photon sieves, this technique can also achieve higher spectral resolution than the conventional spectral imagers, since the technique offers the possibility of separating nearby spectral components that would not otherwise be possible using wavelength filters. These promising aspects are illustrated for solar EUV spectral imaging. Title: Image-Optimized Coronal Magnetic Field Reconstructions Authors: Jones, S. I.; Davila, J. M.; Uritsky, V. M. Bibcode: 2014AGUFMSH21B4120J Altcode: The magnetic field dominates many of the most important and puzzling processes in the corona. In the absence of direct measurements, solar physicists have struggled for decades to accurately reconstruct the coronal magnetic field using photospheric magnetograms. Even with today's excellent magnetographs, these reconstructions are plagued by several problems, among them long computation time, and poor agreement with the structures seen in EUV and coronagraph images. However no method exists for systematically improving the agreement between coronal images and magnetic reconstructions. Solar Orbiter and Solar Probe Plus will bring us closer to the sun we have ever been before, but taking full advantage of that opportunity requires accurate coronal magnetic field reconstructions so that we can connect the in situ observations offered by these unique missions to magnetic sources at the surface of the Sun. In this study we propose a method to improve coronal magnetic field reconstructions by optimizing agreement between the reconstructed field and white-light coronagraph images. Title: Global Variation of the Coronal Electron Density with Solar Cycle and its Comparison with 3D MHD Modeling Authors: Reginald, N. L.; Wang, T.; Davila, J. M. Bibcode: 2014AGUFMSH33A4123R Altcode: The temporal variations of the total or integrated radiance of the K-corona were found to be correlated with solar activity (or sunspot) cycle in some previous studies. In this study, we address the question on how the global electron content of the corona varies with the solar cycle by analyzing STEREO/COR1 pB images over a period from 2007 (near solar minimum of Solar Cycle 23) to 2014 (near solar maximum of Solar Cycle 24). We reconstruct the 3D coronal density by using a spherically symmetric polynomial approximation (SSPA) method on the COR1-A and -B data gathered over half a solar rotation. We find that the total mass of the corona within 1.5-3.7 solar radius reaches a minimum at solar minimum near 2009 and then stays stable until 2010 when the solar activity starts to again increase. The coronal mass is seen to increase by a factor ≈2 from solar minimum to solar maximum while exhibiting strong variations. We explore the cause of this variation by exploring its relationship with the temporal variation of total magnetic flux of the close fields using PFSS extrapolations to SOHO/MDI and SDO/MHI magnetic field data. In addition, for some selected solar rotations we compare the reconstructed 3D density structures with density structures predicted by the Corona Heliosphere (CORHEL) and Magnetohydrodynamics Around the Sphere (MAS) models in the Community Coordinated Modeling Center (CCMC) to understand the physical mechanism that determines the distribution and evolution of the coronal densities. Title: Slitless Solar Spectroscopy Authors: Kamalabadi, F.; Oktem, F. S.; Davila, J. M. Bibcode: 2014AGUFMSH53B4215K Altcode: Spectrometers provide our most detailed diagnostics of the solar coronal plasma, and spectral data is routinely used to measure the temperature, density, and flow velocity of coronal features. However, spectrographs suffer from a limited instantaneous field-of-view (FOV). Imaging instruments can provide a large FOV but offer only very limited spectral resolution. In this work, we present an instrument concept that combines the strengths of these two instrument classes, i.e., a large FOV and high spectral resolution. Our approach is based on computational imaging, which involves distributing the spectral imaging task between a physical and a computational system, and then digitally forming images of interest from multiplexed measurements by means of solving an inverse problem. In particular, a nonscanning spectral imaging technique is developed to enable performing spectroscopy over a two-dimensional instantaneous field-of-view. This technique combines a parametric estimation approach with a slitless spectrometer configuration. The associated inverse problem, which can be viewed as a multiframe image deblurring problem, is formulated in a Bayesian estimation framework and computationally efficient algorithms are designed to solve the resulting nonlinear optimization problems. Furthermore, statistical bounds are obtained to characterize the estimation uncertainties and performance limits, and to explore the optimized system design for specific observing requirements. We illustrate that such an instrument concept will facilitate the investigation of highly dynamic solar phenomena such as flares, CMEs, and transient brightening, with a significant reduction in hardware cost and complexity, but at an accuracy comparable with conventional designs. Title: 3D Coronal Density Reconstruction and Retrieving Coronal Magnetic Field Structures during Solar Minimum and Maximum Authors: Kramar, M.; Airapetian, V.; Davila, J. M. Bibcode: 2014AGUFMSH13A4068K Altcode: Measurement of the coronal magnetic field is a crucial ingredient in understanding the nature of solar coronal phenomena at all scales. We employ STEREO/COR1 data obtained during minimum and maximum of solar activity (Carrington rotations, CR, 2066 and 2131) to retrieve and analyze the three-dimensional (3D) coronal electron density in the range of heights from 1.5 to 4 Rsun using the tomography method and qualitatively deduce structures of the coronal magnetic field. The 3D electron density analysis is complemented by the 3D STEREO/EUVI emissivity in 195 A band obtained by tomography for the same CR periods. A global 3D thermodynamic MHD model of the solar corona was used to relate the reconstructed 3D density and emissivity to open/closed magnetic field structures. We show that the locations of density maximum can serve as an indicator of current sheet position, while the locations of the maximum of the density gradient can be a reliable indicator of closed-open magnetic field boundaries. We find that the magnetic field configuration during CR 2066 has a tendency to become radially open at heliocentric distances above 2.5 Rsun. We also find that the potential field model with a fixed source surface (PFSS) is not consistent with the positions of the boundaries between the regions with open and closed magnetic field structures. This indicates that the assumption of the potential nature of the coronal global magnetic field is not satisfied even during the deep solar minimum. Results of our 3D density reconstruction will help to constrain solar coronal field models and test the accuracy of the magnetic field approximations for coronal modeling. Title: SDO/AIA Observation and Modeling of Flare-excited Slow Waves in Hot Coronal Loops Authors: Wang, T.; Ofman, L.; Provornikova, E.; Sun, X.; Davila, J. M. Bibcode: 2014AGUFMSH13A4074W Altcode: The flare-excited standing slow waves were first detected by SOHO/SUMER as Doppler shift oscillations in hot (>6 MK) coronal loops. It has been suggested that they are excited by small or micro- flares at one loop's footpoint. However, the detailed excitation mechanism remains unclear. In this study, we report an oscillation event observed by SDO/AIA in the 131 channel. The intensity disturbances excited by a C-class flare propagated back and forth along a hot loop for about two period with a strong damping. From the measured oscillation period and loop length, we estimate the wave phase speed to be about 410 km/s. Using a regularized DEM analysis we determine the loop temperature and electron density evolution and find that the loop plasma is heated to a temperature of 8-12 MK with a mean about 9 MK. These measurements support the interpretation as slow magnetoacousic waves. Magnetic field extrapolation suggests that the flare is triggered by slipping and null-point-type reconnections in a fan-spine magnetic topology, and the injected (or impulsively evaporated) hot plasmas flowing along the large spine field lines form the oscillating hot loops. To understand why the propagating waves but not the standing waves as observed previously are excited in this event, we preform simulations using a 3D MHD model based on the observed magnetic configuration including full energy equation. Our simulations indicate that the nature of loop temperature structure is critical for the excitation of whether propagating or standing waves in a hot loop. Our result demonstrates that the slow waves may be used for heating diagnostics of coronal loops with coronal seismology. We also discuss the application of coronal seismology for estimating the average magnetic field strength in the hot loop based on the observed slow waves. Title: Spatiotemporal Organization of Energy Release Events in the Quiet Solar Corona Authors: Uritsky, Vadim M.; Davila, Joseph M. Bibcode: 2014ApJ...795...15U Altcode: 2014arXiv1404.1086U Using data from the STEREO and SOHO spacecraft, we show that temporal organization of energy release events in the quiet solar corona is close to random, in contrast to the clustered behavior of flaring times in solar active regions. The locations of the quiet-Sun events follow the meso- and supergranulation pattern of the underling photosphere. Together with earlier reports of the scale-free event size statistics, our findings suggest that quiet solar regions responsible for bulk coronal heating operate in a driven self-organized critical state, possibly involving long-range Alfvénic interactions. Title: Validation of Spherically Symmetric Inversion by Use of a Tomographically Reconstructed Three-Dimensional Electron Density of the Solar Corona Authors: Wang, Tongjiang; Davila, Joseph M. Bibcode: 2014SoPh..289.3723W Altcode: 2014arXiv1404.5925W; 2014SoPh..tmp...95W Determining the coronal electron density by the inversion of white-light polarized brightness (pB) measurements by coronagraphs is a classic problem in solar physics. An inversion technique based on the spherically symmetric geometry (spherically symmetric inversion, SSI) was developed in the 1950s and has been widely applied to interpret various observations. However, to date there is no study of the uncertainty estimation of this method. We here present the detailed assessment of this method using a three-dimensional (3D) electron density in the corona from 1.5 to 4 R as a model, which is reconstructed by a tomography method from STEREO/COR1 observations during the solar minimum in February 2008 (Carrington Rotation, CR 2066). We first show in theory and observation that the spherically symmetric polynomial approximation (SSPA) method and the Van de Hulst inversion technique are equivalent. Then we assess the SSPA method using synthesized pB images from the 3D density model, and find that the SSPA density values are close to the model inputs for the streamer core near the plane of the sky (POS) with differences generally smaller than about a factor of two; the former has the lower peak but extends more in both longitudinal and latitudinal directions than the latter. We estimate that the SSPA method may resolve the coronal density structure near the POS with angular resolution in longitude of about 50°. Our results confirm the suggestion that the SSI method is applicable to the solar minimum streamer (belt), as stated in some previous studies. In addition, we demonstrate that the SSPA method can be used to reconstruct the 3D coronal density, roughly in agreement with the reconstruction by tomography for a period of low solar activity (CR 2066). We suggest that the SSI method is complementary to the 3D tomographic technique in some cases, given that the development of the latter is still an ongoing research effort. Title: 3D Coronal Density Reconstruction and Retrieving the Magnetic Field Structure during Solar Minimum Authors: Kramar, M.; Airapetian, V.; Mikić, Z.; Davila, J. Bibcode: 2014SoPh..289.2927K Altcode: 2014SoPh..tmp...63K; 2014arXiv1405.0951K Measurement of the coronal magnetic field is a crucial ingredient in understanding the nature of solar coronal phenomena at all scales. We employed STEREO/COR1 data obtained during a deep minimum of solar activity in February 2008 (Carrington Rotation CR 2066) to retrieve and analyze the three-dimensional (3D) coronal electron density in the range of heights from 1.5 to 4 R using a tomography method. With this, we qualitatively deduced structures of the coronal magnetic field. The 3D electron-density analysis is complemented by the 3D STEREO/EUVI emissivity in the 195 Å band obtained by tomography for the same CR. A global 3D MHD model of the solar corona was used to relate the reconstructed 3D density and emissivity to open/closed magnetic-field structures. We show that the density-maximum locations can serve as an indicator of current-sheet position, while the locations of the density-gradient maximum can be a reliable indicator of coronal-hole boundaries. We find that the magnetic-field configuration during CR 2066 has a tendency to become radially open at heliocentric distances greater than 2.5 R. We also find that the potential-field model with a fixed source surface is inconsistent with the boundaries between the regions with open and closed magnetic-field structures. This indicates that the assumption of the potential nature of the coronal global magnetic field is not satisfied even during the deep solar minimum. Results of our 3D density reconstruction will help to constrain solar coronal-field models and test the accuracy of the magnetic-field approximations for coronal modeling. Title: Ground Level Enhancement in the 2014 January 6 Solar Energetic Particle Event Authors: Thakur, N.; Gopalswamy, N.; Xie, H.; Mäkelä, P.; Yashiro, S.; Akiyama, S.; Davila, J. M. Bibcode: 2014ApJ...790L..13T Altcode: 2014arXiv1406.7172T We present a study of the 2014 January 6 solar energetic particle event which produced a small ground level enhancement (GLE), making it the second GLE of this unusual solar cycle 24. This event was primarily observed by the South Pole neutron monitors (increase of ~2.5%) while a few other neutron monitors recorded smaller increases. The associated coronal mass ejection (CME) originated behind the western limb and had a speed of 1960 km s-1. The height of the CME at the start of the associated metric type II radio burst, which indicates the formation of a strong shock, was measured to be 1.61 Rs using a direct image from STEREO-A/EUVI. The CME height at the time of the GLE particle release (determined using the South Pole neutron monitor data) was directly measured as 2.96 Rs based on STEREO-A/COR1 white-light observations. These CME heights are consistent with those obtained for GLE71, the only other GLE of the current cycle, as well as cycle-23 GLEs derived using back-extrapolation. GLE72 is of special interest because it is one of only two GLEs of cycle 24, one of two behind-the-limb GLEs, and one of the two smallest GLEs of cycles 23 and 24. Title: Performance Measurements of an Intensified APS Detector for SPICE on Solar Orbiter Authors: Thompson, William T.; Davila, Joseph M.; Woytko, Gregory; Devlin, Thomas; Jordan, Patrick; Rosanova, Alberto; Chang, William; Reginald, Nelson Leslie; Plummer, Thomas; Haas, Patrick; Caldwell, Martin; Anderson, Mark; Eccleston, Paul; Griffin, Douglas; Siegmund, Oswald Bibcode: 2014AAS...22412357T Altcode: The Spectral Imaging of the Coronal Environment (SPICE) instrument for the Solar Orbiter mission will make spectroscopic observations of the Sun's low corona to characterize the plasma properties of the source regions of the solar wind. The detector package for SPICE, provided by the NASA Goddard Space FLight Center, consists of two microchannel-plate (MCP) intensified Active Pixel Sensor (APS) detectors covering the short (702-792 Angstroms) and long (972-1050 Angstroms) wavelength bandpasses. The long wavelength detector will also provide coverage in second order between 485-525 Angstroms. We report here on measurements made on the engineering model of the SPICE detector in a vacuum tank facility at the Rutherford Appleton Laboratory in Harwell, UK. These measurements include the detector flat field, sensitivity, resolution, linearity, and statistical noise. A krypton resonance lamp operating at 1236 Angstroms was used to stimulate the detector. Results at this wavelength are combined with the quantum efficiency measurements of the individual MCPs at this and other wavelengths covering the entire wavelength range to provide a complete calibration curve for the instrument. A calibrated NIST photodiode was used to determine the absolute brightness of the lamp. Title: Validation of Spherically Symmetric Inversion by Use of a Tomographic Reconstructed Three-Dimensional Electron Density of the Solar Corona Authors: Wang, Tongjiang; Kramar, Maxim; Davila, Joseph M. Bibcode: 2014AAS...22432330W Altcode: Determination of the coronal electron density by the inversion of white-light polarized brightness (pB) measurements by coronagraphs is a classic problem in solar physics. An inversion technique based on the spherically symmetric geometry (Spherically Symmetric Inversion, SSI) was developed in the 1950s, and has been widely applied to interpret various observations. In this study we present the detailed assessment of this method using a model in terms of three-dimensional (3D) electron density in the corona from 1.5 to 4 solar radii reconstructed by tomography method from STEREO/COR1 observations. We first show in theory and observation that the spherically symmetric polynomial approximation (SSPA) method and the Van de Hulst inversion technique are equivalent. Then we assess the SSPA method using synthesized pB images from the 3D density model, and find that the SSPA density values for edge-on streamers are very close to the model inputs in the plane of sky with differences generally less than a factor of two or so; the SSPA density has the lower peak but more spread in latitudinal direction than in the model. Our results confirm the previous suggestion that the SSI method is very suitable to streamers in the solar minimum. In addition, we demonstrate that the SSPA method can be used to reconstruct the 3D coronal density, roughly in agreement with that by tomography in a period of low solar activity. We suggest that the SSI method is complementary to the 3D tomographic technique in some cases, given that the development of the latter is still an ongoing research effort. Title: Evaluating the Uncertainties in the Electron Temperature and Radial Speed Measurements Using White Light Corona Eclipse Observations Authors: Reginald, Nelson L.; Davila, Joseph M.; St. Cyr, O. C.; Rastaetter, Lutz Bibcode: 2014SoPh..289.2021R Altcode: 2014SoPh..tmp....4R We examine the uncertainties in two plasma parameters from their true values in a simulated asymmetric corona. We use the Corona Heliosphere (CORHEL) and Magnetohydrodynamics Around the Sphere (MAS) models in the Community Coordinated Modeling Center (CCMC) to investigate the differences between an assumed symmetric corona and a more realistic, asymmetric one. We were able to predict the electron temperatures and electron bulk flow speeds to within ± 0.5 MK and ± 100 km s−1, respectively, over coronal heights up to 5.0 R from Sun center. We believe that this technique could be incorporated in next-generation white-light coronagraphs to determine these electron plasma parameters in the low solar corona. We have conducted experiments in the past during total solar eclipses to measure the thermal electron temperature and the electron bulk flow speed in the radial direction in the low solar corona. These measurements were made at different altitudes and latitudes in the low solar corona by measuring the shape of the K-coronal spectra between 350 nm and 450 nm and two brightness ratios through filters centered at 385.0 nm/410.0 nm and 398.7 nm/423.3 nm with a bandwidth of ≈ 4 nm. Based on symmetric coronal models used for these measurements, the two measured plasma parameters were expected to represent those values at the points where the lines of sight intersected the plane of the solar limb. Title: SDO/AIA observations and model of standing waves in hot coronal loops excited by a flare Authors: Wang, Tongjiang; Ofman, Leon; Provornikova, Elena; Davila, Joseph M. Bibcode: 2014AAS...22432354W Altcode: The strongly damped Doppler shift oscillations in hot coronal loops were first observed by SOHO/SUMER in flare lines formed at plasma temperature more than 6 MK. They were mainly interpreted as the standing slow magnetosonic waves excited by impulsive energy release at the loop’s footpoint based on the measured properties and on MHD modeling results. Longitudinal waves with similar properties have been recently observed by SDO/AIA in active region loops. In this study, we report a new event that exhibited the flare-excited intensity disturbances propagating back and forth in a hot coronal loop imaged by AIA in 131 bandpass. We measure the physical parameters of the wave and loop plasma, determine the loop geometry, and explore the triggering mechanism. We identify the wave modes (propagating or standing waves) based on these measurements and on 3D MHD modeling. A loop model is constructed with enhanced density in a hydrostatic equilibrium following potential or force-free magnetic field lines extrapolated from the photospheric magnetic field data observed by SDO/HMI. We also discuss the applications of coronal seismology to this event. Title: Slitless Solar Spectroscopy Authors: O'Neill, John Francis; Davila, Joseph M.; Oktem, Figen S Bibcode: 2014AAS...22412359O Altcode: Spectrographs have traditionally suffered from the inability to obtain line intensities, widths, and Doppler shifts over large spatial regions of the Sun quickly because of their narrow instantaneous field of view. This has limited the spectroscopic analysis of rapidly varying solar features like, flares, CME eruptions, coronal jets, and reconnection regions. Imagers, on the other hand, have provided high time resolution images of the full Sun with limited spectral resolution.In this paper we present recent advances in deconvolving spectrally dispersed images obtained through broad slits. We use this new theoretical formulation to examine the effectiveness of various potential observing scenarios, spatial and spectral resolutions, signal to noise ratio, and other instrument characteristics. We test this method on two specific observing scenarios.With the original method developed for the single spectral line case, we first analyze the effect of overlapping spectral lines on the resulting spectral parameters. Second, we determine how well the method performs when given dispersed image input with either three orders (0, +1, -1), or with two orders (0, +1). In both cases a more accurate Gauss error function calculation is employed on the dispersed images. This information will lay the foundation for a new generation of spectral imagers optimized for slitless spectral operation, enabling us to obtain spectral information in transient solar events. Title: Slitless Spectroscopy Authors: Davila, J. M.; O'Neill, J. F. Bibcode: 2013AGUFMSM52A..05D Altcode: Spectrographs provide a unique window into plasma parameters in the solar atmosphere. In fact spectrographs provide the most accurate measurements of plasma parameters such as density, temperature, and flow speed. However, traditionally spectrographic instruments have suffered from the inability to cover large spatial regions of the Sun quickly. To cover an active region sized spatial region, the slit must be rastered over the area of interest with an exposure taken at each pointing location. Because of this long cycle time, the spectra of dynamic events like flares, CME initiations, or transient brightening are obtained only rarely. And even if spectra are obtained they are either taken over an extremely small spatial region, or the spectra are not co-temporal across the raster. Either of these complicates the interpretation of the spectral raster results. Imagers are able to provide high time and spatial resolution images of the full Sun but with limited spectral resolution. The telescopes onboard the Solar Dynamics Observatory (SDO) normally take a full disk solar image every 10 seconds with roughly 1 arcsec spatial resolution. However the spectral resolution of the multilayer imagers on SDO is of order 100 times less than a typical spectrograph. Because of this it is difficult to interpret multilayer imaging data to accurately obtain plasma parameters like temperature and density from these data, and there is no direct measure of plasma flow velocity. SERTS and EIS partially addressed this problem by using a wide slit to produce monochromatic images with limited FOV to limit overlapping. However dispersion within the wide slit image remained a problem which prevented the determination of intensity, Doppler shift, and line width in the wide slit. Kankelborg and Thomas introduced the idea of using multiple images -1, 0, and +1 spectral orders of a single emission line. This scheme provided three independent images to measure the three spectral line parameters in each pixel with the Multi-Order Solar EUV Spectrograph (MOSES) instrument. We suggest a reconstruction approach based on tomographic methods with regularization. Preliminary results show that the typical Doppler shift and line width error introduced by the reconstruction method is of order a few km/s at 300 A. This is on the order of the error obtained in narrow slit spectrographs but with data obtained over a two-dimensional field of view. Title: Measuring Temperature-dependent Propagating Disturbances in Coronal Fan Loops Using Multiple SDO/AIA Channels and the Surfing Transform Technique Authors: Uritsky, Vadim M.; Davila, Joseph M.; Viall, Nicholeen M.; Ofman, Leon Bibcode: 2013ApJ...778...26U Altcode: 2013arXiv1308.6195U A set of co-aligned high-resolution images from the Atmospheric Imaging Assembly (AIA) on board the Solar Dynamics Observatory is used to investigate propagating disturbances (PDs) in warm fan loops at the periphery of a non-flaring active region NOAA AR 11082. To measure PD speeds at multiple coronal temperatures, a new data analysis methodology is proposed enabling a quantitative description of subvisual coronal motions with low signal-to-noise ratios of the order of 0.1%. The technique operates with a set of one-dimensional "surfing" signals extracted from position-time plots of several AIA channels through a modified version of Radon transform. The signals are used to evaluate a two-dimensional power spectral density distribution in the frequency-velocity space that exhibits a resonance in the presence of quasi-periodic PDs. By applying this analysis to the same fan loop structures observed in several AIA channels, we found that the traveling velocity of PDs increases with the temperature of the coronal plasma following the square-root dependence predicted for slow mode magneto-acoustic waves which seem to be the dominating wave mode in the loop structures studied. This result extends recent observations by Kiddie et al. to a more general class of fan loop system not associated with sunspots and demonstrating consistent slow mode activity in up to four AIA channels. Title: Solar Eruptive Events (SEE) 2020 Mission Concept Authors: Lin, R. P.; Caspi, A.; Krucker, S.; Hudson, H.; Hurford, G.; Bandler, S.; Christe, S.; Davila, J.; Dennis, B.; Holman, G.; Milligan, R.; Shih, A. Y.; Kahler, S.; Kontar, E.; Wiedenbeck, M.; Cirtain, J.; Doschek, G.; Share, G. H.; Vourlidas, A.; Raymond, J.; Smith, D. M.; McConnell, M.; Emslie, G. Bibcode: 2013arXiv1311.5243L Altcode: Major solar eruptive events (SEEs), consisting of both a large flare and a near simultaneous large fast coronal mass ejection (CME), are the most powerful explosions and also the most powerful and energetic particle accelerators in the solar system, producing solar energetic particles (SEPs) up to tens of GeV for ions and hundreds of MeV for electrons. The intense fluxes of escaping SEPs are a major hazard for humans in space and for spacecraft. Furthermore, the solar plasma ejected at high speed in the fast CME completely restructures the interplanetary medium (IPM) - major SEEs therefore produce the most extreme space weather in geospace, the interplanetary medium, and at other planets. Thus, understanding the flare/CME energy release process(es) and the related particle acceleration processes are major goals in Heliophysics. To make the next major breakthroughs, we propose a new mission concept, SEE 2020, a single spacecraft with a complement of advanced new instruments that focus directly on the coronal energy release and particle acceleration sites, and provide the detailed diagnostics of the magnetic fields, plasmas, mass motions, and energetic particles required to understand the fundamental physical processes involved. Title: Global Coronal Seismology in the Extended Solar Corona through Fast Magnetosonic Waves Observed by STEREO SECCHI COR1 Authors: Kwon, Ryun-Young; Kramar, Maxim; Wang, Tongjiang; Ofman, Leon; Davila, Joseph M.; Chae, Jongchul; Zhang, Jie Bibcode: 2013ApJ...776...55K Altcode: We present global coronal seismology for the first time, which allows us to determine inhomogeneous magnetic field strength in the extended corona. From the measurements of the propagation speed of a fast magnetosonic wave associated with a coronal mass ejection (CME) and the coronal background density distribution derived from the polarized radiances observed by the STEREO SECCHI COR1, we determined the magnetic field strengths along the trajectories of the wave at different heliocentric distances. We found that the results have an uncertainty less than 40%, and are consistent with values determined with a potential field model and reported in previous works. The characteristics of the coronal medium we found are that (1) the density, magnetic field strength, and plasma β are lower in the coronal hole region than in streamers; (2) the magnetic field strength decreases slowly with height but the electron density decreases rapidly so that the local fast magnetosonic speed increases while plasma β falls off with height; and (3) the variations of the local fast magnetosonic speed and plasma β are dominated by variations in the electron density rather than the magnetic field strength. These results imply that Moreton and EIT waves are downward-reflected fast magnetosonic waves from the upper solar corona, rather than freely propagating fast magnetosonic waves in a certain atmospheric layer. In addition, the azimuthal components of CMEs and the driven waves may play an important role in various manifestations of shocks, such as type II radio bursts and solar energetic particle events. Title: Vector Tomography for the Coronal Magnetic Field. II. Hanle Effect Measurements Authors: Kramar, M.; Inhester, B.; Lin, H.; Davila, J. Bibcode: 2013ApJ...775...25K Altcode: In this paper, we investigate the feasibility of saturated coronal Hanle effect vector tomography or the application of vector tomographic inversion techniques to reconstruct the three-dimensional magnetic field configuration of the solar corona using linear polarization measurements of coronal emission lines. We applied Hanle effect vector tomographic inversion to artificial data produced from analytical coronal magnetic field models with equatorial and meridional currents and global coronal magnetic field models constructed by extrapolation of real photospheric magnetic field measurements. We tested tomographic inversion with only Stokes Q, U, electron density, and temperature inputs to simulate observations over large limb distances where the Stokes I parameters are difficult to obtain with ground-based coronagraphs. We synthesized the coronal linear polarization maps by inputting realistic noise appropriate for ground-based observations over a period of two weeks into the inversion algorithm. We found that our Hanle effect vector tomographic inversion can partially recover the coronal field with a poloidal field configuration, but that it is insensitive to a corona with a toroidal field. This result demonstrates that Hanle effect vector tomography is an effective tool for studying the solar corona and that it is complementary to Zeeman effect vector tomography for the reconstruction of the coronal magnetic field. Title: Three-dimensional Magnetohydrodynamic Modeling of Propagating Disturbances in Fan-like Coronal Loops Authors: Wang, Tongjiang; Ofman, Leon; Davila, Joseph M. Bibcode: 2013ApJ...775L..23W Altcode: 2013arXiv1308.0282W Quasi-periodic propagating intensity disturbances (PDs) have been observed in large coronal loops in EUV images over a decade, and are widely accepted to be slow magnetosonic waves. However, spectroscopic observations from Hinode/EIS revealed their association with persistent coronal upflows, making this interpretation debatable. Motivated by the scenario that the coronal upflows could be the cumulative result of numerous individual flow pulses generated by sporadic heating events (nanoflares) at the loop base, we construct a velocity driver with repetitive tiny pulses, whose energy frequency distribution follows the flare power-law scaling. We then perform three-dimensional MHD modeling of an idealized bipolar active region by applying this broadband velocity driver at the footpoints of large coronal loops which appear open in the computational domain. Our model successfully reproduces the PDs with similar features as the observed, and shows that any upflow pulses inevitably excite slow magnetosonic wave disturbances propagating along the loop. We find that the generated PDs are dominated by the wave signature as their propagation speeds are consistent with the wave speed in the presence of flows, and the injected flows rapidly decelerate with height. Our simulation results suggest that the observed PDs and associated persistent upflows may be produced by small-scale impulsive heating events (nanoflares) at the loop base in the corona, and that the flows and waves may both contribute to the PDs at lower heights. Title: Fast Magnetosonic Waves and Global Coronal Seismology in the Extended Solar Corona Authors: Kwon, Ryun Young; Zhang, J.; Kramar, M.; Wang, T.; Ofman, L.; Davila, J. M. Bibcode: 2013SPD....4410303K Altcode: We present global coronal seismology, for the first time, that allows us to determine inhomogeneous magnetic field strengths in a wide range of the extended solar corona. We use observations of propagating disturbance associated with a coronal mass ejection observed on 2011 August 4 by the COR1 inner coronagraphs on board the STEREO spacecraft. We establish that the disturbance is in fact a fast magnetosonic wave as the upper coronal counterpart of the EIT wave observed by STEREO EUVI and travels across magnetic field lines with inhomogeneous speeds, passing through various coronal regions such as quiet/active corona, coronal holes, and streamers. We derive magnetic field strengths along the azimuthal trajectories of the fronts at heliocentric distances 2.0, 2.5, and 3.0 Rs, using the varying speeds and electron densities. The derived magnetic field strengths are consistent with values determined with a potential field source surface model and reported in previous works. The ranges of the magnetic field strengths at these heliocentric distances are 0.44 ± 0.29, 0.23 ± 0.15, and 0.26 ± 0.14 G, respectively. The uncertainty in determining magnetic field strengths is about 40 %. This work demonstrates that observations of fast magnetosonic waves by white-light coronagraphs can provide us with a unique way to diagnose magnetic field strength of an inhomogeneous medium in a wide spatial range of the extended solar corona. 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: Modeling coronal loop oscillations in realistic magnetic and density structures Authors: Ofman, Leon; Wang, T.; Malanushenko, A.; Davila, J. M. Bibcode: 2013SPD....4410404O Altcode: Recently, ubiquitous coronal loop oscillations were detected in active region loops by SDO/AIA. Hinode/EIS observations indicate that quasi-periodic flows are present at footpoints of loops in active regions, and related propagating disturbances (PD's) were detected in open and closed loop structures. Recent 3D MHD models in idealized (bipolar) active regions (Ofman et al. 2012; Wang et al. 2013, this meeting) have demonstrated that the flows can produce slow magnetosonic waves in loops, as well as transverse oscillations. We extend the idealized studies by considering more realistic magnetic field structures modeled by including photospheric magnetic field extrapolated to the corona as boundary and initial conditions for the 3D MHD modeling. We use potential and nonlinear magnetic field extrapolations combined with gravitationally stratified density and introduce flows at the corona-transition region boundary in our 3D MHD model. We apply coronal seismology to the resulting loop oscillations and compare to oscillation events detected by SDO/AIA. We aim to improve the accuracy of coronal seismology by modeling coronal loop oscillations in realistic magnetic geometry and density structures. Title: Three-Dimensional MHD Modeling of Propagating Disturbances in Fanlike AR Coronal Loops Authors: Wang, Tongjiang; Ofman, L.; Davila, J. M. Bibcode: 2013SPD....44...36W Altcode: Quasi-periodic propagating intensity disturbances (PDs) have been observed in cool (about 1 MK) coronal loops in EUV images over a decade. They are widely accepted to be slow magnetosonic waves since their propagation velocity is close to the coronal sound speed. However, recent spectroscopic observations from Hinode/EIS revealed their association with persistent coronal upflows, making this interpretation debatable. Motivated by the scenario that the observed persistent upflows could be cumulative result of numerous individual flow pulses generated by sporadic heating events (nanoflares) at the loop base, we constructed a broadband velocity driver with repetative tiny pulses, whose energy frequency distribution follows the flare power-law scaling distribution. We then performed 3D MHD modeling of an idealized bipolar active region by applying this broadband velocity driver at the footpoints of coronal loops which appear open in the computational domain. Our model successfully reproduced the propagating disturbances with similar features as the observed. We find, based on our simulations, that upflow pulses unavoidably excites a slow magnetosonic wave fronts propagating along the loop with the phase speed which is much larger than the local flow speed as the flow velocity decreases with height. Our modeling results support that the observed PDs are mainly the signature of waves above the footpoints of the loops, and suggest that the observed PDs and associated persistent upflows may be driven by the same mechanism such as impulsive heating at the loop base. Title: Slow mode waves and quasi-periodic upflows in the multi-temperature solar corona as seen by the SDO Authors: Uritsky, Vadim; Davila, J. M.; Viall, N.; Ofman, L. Bibcode: 2013SPD....4410405U Altcode: We report results the analysis of coronal fan loops in a non-flaring solar active region exhibiting temperature-dependent propagating optical disturbances. A 6-hour set of high resolution coronal observations provided by the Atmospheric Imaging Assembly (AIA) on board the Solar Dynamics Observatory (SDO) has been used for characterizing apparent propagating patterns at multiple coronal temperatures (131A, 171A, 193A and 211A). A new data analysis methodology has been developed enabling an identification of subvisual motions with low signal-to-noise ratios not previously examined in this context. The technique involves spatiotemporal tracking of fan loop filaments containing propagating disturbances, construction of position - time plots for different temperature channels, obtaining the waveforms of the propagating optical features, and evaluation of Fourier spectral power of the waveforms as a function of phase speed and frequency. Using this methodology, we identified the parameters of propagating optical disturbances in different magnetic geometries, and classified these events as waves and/or plasma jets. We explored coronal conditions favoring wave-like and jet-like traveling plasma density enhancements in fan loops and the mechanisms of their generation, damping and interaction. The results obtained are compared with the behavior of a resistive MHD model exhibiting both types of propagating disturbances. Title: Structure of the Coronal Streamers During Solar Minimum and Maximum Authors: Kramar, Maxim; Davila, J.; Mikic, Z. Bibcode: 2013SPD....44...11K Altcode: We analyze the meridional cross-section of the 3D coronal electron density in the range from 1.5 to 4 R_⊙ obtained by the tomography method during minimum and beginning of maximum of solar activity corresponding to February 2008 and July 2011, respectively. The importance of this coronal region is that it contains the transition from closed to open magnetic coronal structures. At the moment, only STEREO/COR1 provides observation that provides information on the coronal structure in this region. Therefore, analysis of 3D coronal density structure is critical for deriving the position where transition from closed to open magnetic coronal structures occurs. The 3D coronal density in the region of interest has been obtained by applying tomographic techniques to white light coronagraph data obtained by STEREO/COR1 instrument. It is shown that enhanced density structures associated with coronal streamers and pseudostreamers have a tendency to become radially directed at heliocentric distances of about 3 and 2 $R_\odot$ during minimum and maximum of solar activity, respectively. Potential Field models (PFSS) with several different values of the Source Surface position have been analyzed for consistency with the obtained 3D coronal density structure. Title: Global Coronal Seismology in the Extended Solar Corona through Fast Magnetosonic Waves Observed by STEREO SECCHI COR1 Authors: Kwon, Ryun Young; Zhang, Jie; Kramar, Maxim; Wang, Tongjiang; Ofman, Leon; Davila, Joseph M. Bibcode: 2013shin.confE..75K Altcode: We present global coronal seismology, for the first time, that allows us to determine inhomogeneous magnetic field strengths in a wide range of the extended solar corona. We use observations of a fast magnetosonic wave associated with a coronal mass ejection observed on 2011 August 4 by the COR1 inner coronagraphs on board the STEREO spacecraft. In order to estimate inhomogeneous magnetic field strength, we choose the azimuthal trajectories of the wave front at heliocentric distances 2.0, 2.5, and 3.0 solar radii and determine the speeds of the wave front and electron densities using polarized brightness images along the trajectories. The magnetic field strengths are derived with an uncertainty less than 40 % and consistent with values determined with a potential field source surface model and reported in previous works. The characteristics of the coronal medium revealed with our global coronal seismology are that: (1) density, magnetic field strength, plasma beta are lower in the coronal hole than in the streamers, (2) magnetic field strength decreases slowly with height but electron density decreases rapidly so that local fast magnetosonic speed increases while plasma beta falls off with height, and (3) the variations of local fast magnetosonic speed and plasma beta are in accordance with the electron density rather than magnetic field strength. These characteristics of the coronal medium imply that Moreton and EIT waves are downward shock fronts of fast magnetosonic waves refracted from the upper solar corona, rather than freely propagating fast magnetosonic waves in a certain solar atmospheric layer. In addition, the azimuthal components of CMEs may play an important role in various manifestations of shocks, such as type II radio bursts and solar energetic particle events. Title: Coronal Magnetic Field Reconstruction based on HAO/CoMP observations. Authors: Kramar, Maxim; Lin, H.; Tomczyk, S.; Davila, J. Bibcode: 2013shin.confE..89K Altcode: The magnetic field is the dominant force source in the solar coronal plasma, the one that shapes its structure. Synoptic observations that provide a direct information about the magnetic field have been recently became available by High Altitude Observatory (HAO) Coronal Multichannel Polarimeter (CoMP). The instrument provides linear polarization maps of the Fe XIII 10747 A 'forbidden' line. The observed linear polarization depends on magnetic field orientation through Hanle effect. These observation, supplied with additional photospheric magnetic field measurements and UV observations, are used for 3D reconstruction of the coronal magnetic field by applying the vector tomography technique. Title: Stochastic Coupling of Solar Photosphere and Corona Authors: Uritsky, Vadim M.; Davila, Joseph M.; Ofman, Leon; Coyner, Aaron J. Bibcode: 2013ApJ...769...62U Altcode: 2012arXiv1212.5610U The observed solar activity is believed to be driven by the dissipation of nonpotential magnetic energy injected into the corona by dynamic processes in the photosphere. The enormous range of scales involved in the interaction makes it difficult to track down the photospheric origin of each coronal dissipation event, especially in the presence of complex magnetic topologies. In this paper, we propose an ensemble-based approach for testing the photosphere-corona coupling in a quiet solar region as represented by intermittent activity in Solar and Heliospheric Observatory Michelson Doppler Imager and Solar TErrestrial RElations Observatory Extreme Ultraviolet Imager image sets. For properly adjusted detection thresholds corresponding to the same degree of intermittency in the photosphere and corona, the dynamics of the two solar regions is described by the same occurrence probability distributions of energy release events but significantly different geometric properties. We derive a set of scaling relations reconciling the two groups of results and enabling statistical description of coronal dynamics based on photospheric observations. Our analysis suggests that multiscale intermittent dissipation in the corona at spatial scales >3 Mm is controlled by turbulent photospheric convection. Complex topology of the photospheric network makes this coupling essentially nonlocal and non-deterministic. Our results are in an agreement with the Parker's coupling scenario in which random photospheric shuffling generates marginally stable magnetic discontinuities at the coronal level, but they are also consistent with an impulsive wave heating involving multiscale Alfvénic wave packets and/or magnetohydrodynamic turbulent cascade. A back-reaction on the photosphere due to coronal magnetic reconfiguration can be a contributing factor. Title: The First Ground Level Enhancement Event of Solar Cycle 24: Direct Observation of Shock Formation and Particle Release Heights Authors: Gopalswamy, N.; Xie, H.; Akiyama, S.; Yashiro, S.; Usoskin, I. G.; Davila, J. M. Bibcode: 2013ApJ...765L..30G Altcode: 2013arXiv1302.1474G We report on the 2012 May 17 ground level enhancement (GLE) event, which is the first of its kind in solar cycle 24. This is the first GLE event to be fully observed close to the surface by the Solar Terrestrial Relations Observatory (STEREO) mission. We determine the coronal mass ejection (CME) height at the start of the associated metric type II radio burst (i.e., shock formation height) as 1.38 Rs (from the Sun center). The CME height at the time of GLE particle release was directly measured from a STEREO image as 2.32 Rs, which agrees well with the estimation from CME kinematics. These heights are consistent with those obtained for cycle-23 GLEs using back-extrapolation. By contrasting the 2012 May 17 GLE with six other non-GLE eruptions from well-connected regions with similar or larger flare sizes and CME speeds, we find that the latitudinal distance from the ecliptic is rather large for the non-GLE events due to a combination of non-radial CME motion and unfavorable solar B0 angle, making the connectivity to Earth poorer. We also find that the coronal environment may play a role in deciding the shock strength. Title: Vertical kink oscillations of coronal loops triggered by recurrent jets Authors: Wang, Tongjiang; Ofman, Leon; Davila, Joseph M. Bibcode: 2013enss.confE..99W Altcode: Transverse coronal loop oscillations were first observed by TRACE in EUV images, and have been interpreted as global standing kink modes. These loop oscillations are thought to be excited by a blast wave in the form of a shock or a fast-mode wave produced by a flare or CME. In this presentation, we report simultaneous imaging and spectroscopic observations with SDO/AIA and Hinode/EIS of a vertical loop oscillations triggered by recurrent jets at the footpoints. These oscillations start with a fast disturbance traveling along the loop with the propagating speed more than 500 km/s, much faster than the apparent EUV jets. The vertical loop oscillations are associated with quasi-periodic outwardly propagating features with the speeds 30-300 km/s, suggestive of loop expansions. In addition, we perform 3D MHD modeling of a typical such event to understand the excitation of kink oscillations by impulsive flows. Title: STEREO Observations of Fast Magnetosonic Waves in the Extended Solar Corona Associated with EIT/EUV Waves Authors: Kwon, Ryun-Young; Ofman, Leon; Olmedo, Oscar; Kramar, Maxim; Davila, Joseph M.; Thompson, Barbara J.; Cho, Kyung-Suk Bibcode: 2013ApJ...766...55K Altcode: We report white-light observations of a fast magnetosonic wave associated with a coronal mass ejection observed by STEREO/SECCHI/COR1 inner coronagraphs on 2011 August 4. The wave front is observed in the form of density compression passing through various coronal regions such as quiet/active corona, coronal holes, and streamers. Together with measured electron densities determined with STEREO COR1 and Extreme UltraViolet Imager (EUVI) data, we use our kinematic measurements of the wave front to calculate coronal magnetic fields and find that the measured speeds are consistent with characteristic fast magnetosonic speeds in the corona. In addition, the wave front turns out to be the upper coronal counterpart of the EIT wave observed by STEREO EUVI traveling against the solar coronal disk; moreover, stationary fronts of the EIT wave are found to be located at the footpoints of deflected streamers and boundaries of coronal holes, after the wave front in the upper solar corona passes through open magnetic field lines in the streamers. Our findings suggest that the observed EIT wave should be in fact a fast magnetosonic shock/wave traveling in the inhomogeneous solar corona, as part of the fast magnetosonic wave propagating in the extended solar corona. Title: Reconstruction of the 3D Coronal Magnetic Field by Vector Tomography with Infrared Spectropolarimetric Observations from CoMP Authors: Kramar, M.; Lin, H.; Tomczyk, S.; Davila, J. M.; Inhester, B. Bibcode: 2012AGUFMSH42A..06K Altcode: Magnetic fields determine the static and dynamic properties of the solar corona. A significant progress has been achieved in direct measurement of the magnetically sensitive coronal emission with deployment of the HAO Coronal Multichannel Polarimeter (CoMP). The instrument provides polarization measurements of Fe XIII 10747 A forbidden line emission. The observed polarization depends on magnetic field through the Hanle and Zeeman effects. However, because the coronal measurements are integrated over line-of-site (LOS), it is impossible to derive the configuration of the coronal magnetic field from a single observation (from a single viewing direction). The vector tomography techniques based on the infrared polarimetric measurements from several viewing directions has been developed in order to resolve the 3D coronal magnetic field structure over LOS. Because of the non-linear character of the Hanle effect, the reconstruction result based on such data is not straightforward and depends on the particular coronal field configuration. For several possible cases of coronal magnetic field configuration, it has been found that even just Stokes-Q and -U data (supplied with 3D coronal density and temperature) can be used in the vector tomography to provide a realistic 3D coronal magnetic field. The 3D coronal density and temperature needed as an supplemental input are reconstructed by the scalar field tomography method using ultraviolet observations from EUVI/STEREO. We will present the reconstructed 3D coronal density, temperature and magnetic field in the range of ∼ 1.3 R obtained by the scalar and vector tomography. Title: A Space Weather Mission to the Earth's 5th Lagrangian Point (L5) Authors: Howard, R. A.; Vourlidas, A.; Ko, Y.; Biesecker, D. A.; Krucker, S.; Murphy, N.; Bogdan, T. J.; St Cyr, O. C.; Davila, J. M.; Doschek, G. A.; Gopalswamy, N.; Korendyke, C. M.; Laming, J. M.; Liewer, P. C.; Lin, R. P.; Plunkett, S. P.; Socker, D. G.; Tomczyk, S.; Webb, D. F. Bibcode: 2012AGUFMSA13D..07H Altcode: The highly successful STEREO mission, launched by NASA in 2006, consisted of two spacecraft in heliocentric orbit, one leading and one trailing the Earth and each separating from Earth at the rate of about 22.5 degrees per year. Thus the two spacecraft have been probing different probe/Sun/Earth angles. The utility of having remote sensing and in-situ instrumentation away from the Sun-Earth line was well demonstrated by STEREO. Here we propose the concept of a mission at the 5th Lagrangian "point" in the Earth/Sun system, located behind Earth about 60 degrees to the East of the Sun-Earth line. Such a mission would enable many aspects affecting space weather to be well determined and thus improving the prediction of the conditions of the solar wind as it impinges on geospace. For example, Coronal Mass Ejections can tracked for a significant distance toward Earth, new active regions can be observed before they become visible to the Earth observer, the solar wind can be measured before it rotates to Earth. The advantages of such a mission will be discussed in this presentation. Title: Hot Precursor Ejecta and Other Peculiarities of the 2012 May 17 Ground Level Enhancement Event Authors: Gopalswamy, N.; Xie, H.; Nitta, N. V.; Usoskin, I.; Davila, J. M. Bibcode: 2012AGUFMSH21A2180G Altcode: We report on the first Ground Level Enhancement (GLE) event of Solar Cycle 24, which occurred on May 17, 2012 from a well-connected region (NOAA AR 11476, N11W76) on the Sun. There has been a real dearth of GLE events during cycle 24: even though the Sun has reached its solar maximum phase, it has produced only this one GLE event. Over the first 4.5 years of solar cycle 23, there were 5 GLE events, which is roughly a third of all the events of that cycle. The recent GLE event was associated with a moderate flare with an X-ray size of only M5.1, well below the median flare size (X3.8) of cycle 23 GLE events. On the other hand, the associated CME was very fast (~2000 km/s), typical of GLE events. During cycle 23, the CME speeds in GLE events ranged from 1203 km/s to 3675 km/s with an average value of 2083 km/s (Gopalswamy et al., 2012). The speed of the cycle 24 GLE was measured accurately because it was a limb event in the SOHO coronagraphic field of view. The CME was also observed by the STEREO coronagraphs, which helped derive the initial acceleration as 1.5 km/s/s, which is also typical of GLE-producing CMEs. We were also able to directly determine the heliocentric distance of the CME (2.3 solar radii (Rs)) at the time of the release of GLE particles because there was a STEREO/COR1 image precisely at the time of the particle release. This result is consistent with what was obtained for the cycle 23 GLE events, including the distance of the CME at the time of metric type II burst onset (1.3 Rs), indicating shock formation very close to the Sun ( ~0.3 Rs above the solar surface). We infer that the shock had to travel an additional 1 Rs before the GLE particles were released. The CME had a precursor in the form of a hot ejecta some tens of minutes before the main eruption. The preceding ejecta is termed hot because it was observed only in the 94 A images obtained by the Solar Dynamics Observatory (SDO). The 94 A images correspond to coronal a temperature of ~6MK. The lower temperature images such as at 193 A did not show the ejecta. The hot ejecta was accelerating and attained a speed of ~70 km/s before it was blasted by the big GLE-producing CMEs. We suggest that the hot material of the precursor ejecta might have been further accelerated by the CME-driven shock resulting in the GLE event. Reference Gopalswamy, N.,Xie, H., Yashiro, S., Akiyama, S., Mäkelä, P., Usoskin, I. G., Properties of Ground Level Enhancement Events and the Associated Solar Eruptions During Solar Cycle 23, Space Science reviews, DOI: 10.1007/s11214-012-9890-4 Title: Exploring Small Spatial Scales in the Transition Region and Solar Corona with the Very High Angular Resolution Imaging Spectrometer (VERIS) Authors: Chua, D. H.; Korendyke, C. M.; Vourlidas, A.; Brown, C. M.; Tun-Beltran, S.; Klimchuk, J. A.; Landi, E.; Seely, J.; Davila, J. M.; Hagood, R.; Roberts, D.; Shepler, E.; Feldman, R.; Moser, J.; Shea, J. Bibcode: 2012AGUFMSH33A2217C Altcode: Theoretical and experimental investigations of the transition region and coronal loops point to the importance of processes occurring on small spatial scales in governing the strong dynamics and impulsive energy release in these regions. As a consequence, high spatial, temporal, and temperature resolution over a broad temperature range, and accuracy in velocity and density determinations are all critical observational parameters. Current instruments lack one or more of these properties. These observational deficiencies have created a wide array of opposing descriptions of coronal loop heating and questions such as whether or not the plasma within coronal loops is multi-thermal or isothermal. High spectral and spatial resolution spectroscopic data are absolutely required to resolve these controversies and to advance our understanding of the dynamics within the solar atmosphere. We will achieve this with the Very High Angular Resolution Imaging Spectrometer (VERIS) sounding rocket payload. VERIS consists of an off-axis paraboloid telescope feeding a very high angular resolution, extreme ultraviolet (EUV) imaging spectrometer that will provide the first ever, simultaneous sub-arcsecond (0.16 arcsecond/pixel) spectra in bright lines needed to study plasma structures in the transition region, quiet corona, and active region core. It will do so with a spectral resolution of >5000 to allow Doppler velocity determinations to better than 3 km/s. VERIS uses a novel two-element, normal incidence optical design with highly reflective, broad wavelength coverage EUV coatings to access a spectral range with broad temperature coverage (0.03-15 MK) and density-sensitive line ratios. Combined with Hinode Solar Optical Telescope (SOT) and ground based observatories, VERIS will deliver simultaneous observations of the entire solar atmosphere from the photosphere to the multi-million degree corona at sub-arcsecond resolution for the first time ever, allowing us to understand the missing link between chromospheric structures and the corona. VERIS will be launched from White Sands Missile Range in early 2013. This paper presents a progress report on the VERIS payload and a summary of observations planned to further our understanding of the fine-scale structure of individual coronal loops and the heating mechanisms operating within them. Title: Three-dimensional Structure and Evolution of Extreme-ultraviolet Bright Points Observed by STEREO/SECCHI/EUVI Authors: Kwon, Ryun-Young; Chae, Jongchul; Davila, Joseph M.; Zhang, Jie; Moon, Yong-Jae; Poomvises, Watanachak; Jones, Shaela I. Bibcode: 2012ApJ...757..167K Altcode: We unveil the three-dimensional structure of quiet-Sun EUV bright points and their temporal evolution by applying a triangulation method to time series of images taken by SECCHI/EUVI on board the STEREO twin spacecraft. For this study we examine the heights and lengths as the components of the three-dimensional structure of EUV bright points and their temporal evolutions. Among them we present three bright points which show three distinct changes in the height and length: decreasing, increasing, and steady. We show that the three distinct changes are consistent with the motions (converging, diverging, and shearing, respectively) of their photospheric magnetic flux concentrations. Both growth and shrinkage of the magnetic fluxes occur during their lifetimes and they are dominant in the initial and later phases, respectively. They are all multi-temperature loop systems which have hot loops (~106.2 K) overlying cooler ones (~106.0 K) with cool legs (~104.9 K) during their whole evolutionary histories. Our results imply that the multi-thermal loop system is a general character of EUV bright points. We conclude that EUV bright points are flaring loops formed by magnetic reconnection and their geometry may represent the reconnected magnetic field lines rather than the separator field lines. Title: LEMUR: Large European module for solar Ultraviolet Research. European contribution to JAXA's Solar-C mission Authors: Teriaca, Luca; Andretta, Vincenzo; Auchère, Frédéric; Brown, Charles M.; Buchlin, Eric; Cauzzi, Gianna; Culhane, J. Len; Curdt, Werner; Davila, Joseph M.; Del Zanna, Giulio; Doschek, George A.; Fineschi, Silvano; Fludra, Andrzej; Gallagher, Peter T.; Green, Lucie; Harra, Louise K.; Imada, Shinsuke; Innes, Davina; Kliem, Bernhard; Korendyke, Clarence; Mariska, John T.; Martínez-Pillet, Valentin; Parenti, Susanna; Patsourakos, Spiros; Peter, Hardi; Poletto, Luca; Rutten, Robert J.; Schühle, Udo; Siemer, Martin; Shimizu, Toshifumi; Socas-Navarro, Hector; Solanki, Sami K.; Spadaro, Daniele; Trujillo-Bueno, Javier; Tsuneta, Saku; Dominguez, Santiago Vargas; Vial, Jean-Claude; Walsh, Robert; Warren, Harry P.; Wiegelmann, Thomas; Winter, Berend; Young, Peter Bibcode: 2012ExA....34..273T Altcode: 2011ExA...tmp..135T; 2011arXiv1109.4301T The solar outer atmosphere is an extremely dynamic environment characterized by the continuous interplay between the plasma and the magnetic field that generates and permeates it. Such interactions play a fundamental role in hugely diverse astrophysical systems, but occur at scales that cannot be studied outside the solar system. Understanding this complex system requires concerted, simultaneous solar observations from the visible to the vacuum ultraviolet (VUV) and soft X-rays, at high spatial resolution (between 0.1'' and 0.3''), at high temporal resolution (on the order of 10 s, i.e., the time scale of chromospheric dynamics), with a wide temperature coverage (0.01 MK to 20 MK, from the chromosphere to the flaring corona), and the capability of measuring magnetic fields through spectropolarimetry at visible and near-infrared wavelengths. Simultaneous spectroscopic measurements sampling the entire temperature range are particularly important. These requirements are fulfilled by the Japanese Solar-C mission (Plan B), composed of a spacecraft in a geosynchronous orbit with a payload providing a significant improvement of imaging and spectropolarimetric capabilities in the UV, visible, and near-infrared with respect to what is available today and foreseen in the near future. The Large European Module for solar Ultraviolet Research (LEMUR), described in this paper, is a large VUV telescope feeding a scientific payload of high-resolution imaging spectrographs and cameras. LEMUR consists of two major components: a VUV solar telescope with a 30 cm diameter mirror and a focal length of 3.6 m, and a focal-plane package composed of VUV spectrometers covering six carefully chosen wavelength ranges between 170 Å and 1270 Å. The LEMUR slit covers 280'' on the Sun with 0.14'' per pixel sampling. In addition, LEMUR is capable of measuring mass flows velocities (line shifts) down to 2 km s - 1 or better. LEMUR has been proposed to ESA as the European contribution to the Solar C mission. Title: The Relationship Between the Expansion Speed and Radial Speed of CMEs Confirmed Using Quadrature Observations of the 2011 February 15 CME Authors: Gopalswamy, N.; Makela, P.; Yashiro, S.; Davila, J. M. Bibcode: 2012SunGe...7....7G Altcode: 2012arXiv1205.0744G It is difficult to measure the true speed of Earth-directed CMEs from a coronagraph along the Sun-Earth line because of the occulting disk. However, the expansion speed (the speed with which the CME appears to spread in the sky plane) can be measured by such coronagraph. In order to convert the expansion speed to radial speed (which is important for space weather applications) one can use empirical relationship between the two that assumes an average width for all CMEs. If we have the width information from quadrature observations, we can confirm the relationship between expansion and radial speeds derived by Gopalswamy et al. (2009a). The STEREO spacecraft were in qudrature with SOHO (STEREO-A ahead of Earth by 87oand STEREO-B 94obehind Earth) on 2011 February 15, when a fast Earth-directed CME occurred. The CME was observed as a halo by the Large-Angle and Spectrometric Coronagraph (LASCO) on board SOHO. The sky-plane speed was measured by SOHO/LASCO as the expansion speed, while the radial speed was measured by STEREO-A and STEREO-B. In addition, STEREO-A and STEREO-B images measured the width of the CME, which is unknown from Earth view. From the SOHO and STEREO measurements, we confirm the relationship between the expansion speed (Vexp) and radial speed (Vrad) derived previously from geometrical considerations (Gopalswamy et al. 2009a): Vrad=1/2 (1 + cot w)Vexp, where w is the half width of the CME. STEREO-B images of the CME, we found that CME had a full width of 7 6o, so w=3 8o. This gives the relation as Vrad=1.1 4 Vexp. From LASCO observations, we measured Vexp=897 km/s, so we get the radial speed as 10 2 3 km/s. Direct measurement of radial speed yields 945 km/s (STEREO-A) and 105 8 km/s (STEREO-B). These numbers are different only by 7.6 % and 3.4 % (for STEREO-A and STEREO-B, respectively) from the computed value. Title: Slow Magnetosonic Waves and Fast Flows in Active Region Loops Authors: Ofman, L.; Wang, T. J.; Davila, J. M. Bibcode: 2012ApJ...754..111O Altcode: 2012arXiv1205.5732O Recent extreme ultraviolet spectroscopic observations indicate that slow magnetosonic waves are present in active region (AR) loops. Some of the spectral data were also interpreted as evidence of fast (~100-300 km s-1) quasi-periodic flows. We have performed three-dimensional magnetohydrodynamic (3D MHD) modeling of a bipolar AR that contains impulsively generated waves and flows in coronal loops. The model AR is initiated with a dipole magnetic field and gravitationally stratified density, with an upflow-driven steadily or periodically in localized regions at the footpoints of magnetic loops. The resulting flows along the magnetic field lines of the AR produce higher density loops compared to the surrounding plasma by injection of material into the flux tubes and the establishment of siphon flow. We find that the impulsive onset of flows with subsonic speeds result in the excitation of damped slow magnetosonic waves that propagate along the loops and coupled nonlinearly driven fast-mode waves. The phase speed of the slow magnetosonic waves is close to the coronal sound speed. When the amplitude of the driving pulses is increased we find that slow shock-like wave trains are produced. When the upflows are driven periodically, undamped oscillations are produced with periods determined by the periodicity of the upflows. Based on the results of the 3D MHD model we suggest that the observed slow magnetosonic waves and persistent upflows may be produced by the same impulsive events at the bases of ARs. Title: Global Cooperation in the Capacity Building Activities on Sun-Earth Connection Studies Authors: Gopalswamy, Nat; Davila, Joseph; Luebken, Franz-Josef; Shepherd, Marianna; Tsuda, Toshitaka Bibcode: 2012cosp...39..650G Altcode: 2012cosp.meet..650G The importance of global cooperation in Sun-Earth connection studies can be readily seen in the formation of a number of international collaborative programs such as the Climate and Weather of the Sun Earth System (CAWSES) by SCOSTEP* and the International Space Weather Initiative (ISWI). ISWI is the continuation of the successful International Heliophysical Year (IHY) program. These programs have brought scientists together to tackle issues of solar-terrestrial phenomena. An important element of these organizations is capacity building activities, which include deployment of low-cost ground based instruments for Sun-Earth connection studies and training young people (scientists and graduate students) from developing countries to operate these instruments and become members of the international solar-terrestrial scientific community. The training also helps young people to make use of data from the vast array of space and ground based instruments currently available for Sun-Earth connection studies. This paper presents a summary of CAWSES and ISWI activities that promote space Sun-Earth connection studies via complementary approaches in international scientific collaborations, capacity building, and public outreach. *Scientific Committee on Solar Terrestrial Physics (SCOSTEP) is an Interdisciplinary Body of the International Council for Science with representations from COSPAR, IAU, IUGG/IAGA, IUPAP, IAMAS, SCAR, and URSI (http://www.yorku.ca/scostep) Title: A Global View of the Energetic Solar Eruptions during 2012 January 19-27 Authors: Gopalswamy, Nat; Davila, Joseph; Kaiser, Michael; Macdowall, Robert; Cyr, Chris; Xie, Hong; Makela, Pertti; Yashiro, Seiji; Poomvises, Watanachak Bibcode: 2012cosp...39..652G Altcode: 2012cosp.meet..652G The rise phase of solar cycle was generally unremarkable and subdued in terms of large solar eruptive events that had significant heliospheric consequences. Towards the end of the rise phase, a series of three coronal mass ejections (CMEs) originated from NOAA active region 11402 that were accompanied by M or X-class flares, significant solar energetic particle events (including the largest event as of this writing), interplanetary type II radio bursts, and shocks. While the particle radiation was very intense in two events, the plasma impact on the magnetosphere was moderate. This paper provides an overview of the eruptive events, focusing on the kinematic evolution of the CMEs in relation to the interplanetary type II radio bursts and shocks. In particular we compare the drift rate variation of the interplanetary type II bursts with the speed variation of the CMEs obtained from heliospheric imaging. We make use of data from the Solar and Heliospheric Observatory (SOHO), Solar Terrestrial Relations Observatory (STEREO), Solar Dynamics Observatory (SDO), Wind, GOES, and ground based observatories for this investigation. Title: 3D Coronal Magnetic Field reconstructed by Vector Tomography Method using CoMP data Authors: Kramar, Maxim; Lin, H.; Tomczyk, S.; Inhester, B.; Davila, J. Bibcode: 2012shin.confE.141K Altcode: Magnetic fields in the solar corona dominates the gas pressure and therefore determine the static and dynamic properties of the corona. Direct measurement of the coronal magnetic field is one of the most challenging problems in observational solar astronomy and recently a significant progress has been achieved here with deployment of the HAO Coronal Multichannel Polarimeter (CoMP). The instrument provides polarization measurements of Fe XIII 10747 A forbidden line emission. The observed polarization depends on magnetic field through the Hanle and Zeeman effects. However, because the coronal measurements are integrated over line-of-site (LOS), it is impossible to derive the configuration of the coronal magnetic field from a single observation (from a single viewing direction). The vector tomography techniques based on measurements from several viewing directions has the potential to resolve the 3D coronal magnetic field structure over LOS. Because of the non-linear character of the Hanle effect, the reconstruction result based on such data is not straightforward and depends on the particular coronal field configuration. Therefore, previously we also studied what is the sensitivity of the vector tomographic inversion to various coronal magnetic field models. For several possible cases of coronal magnetic field configuration, it has been found that even just Stokes-Q and -U data (supplied with 3D coronal density and temperature) can be used in vector tomography to provide a realistic 3D coronal magnetic field configuration. The 3D coronal density and temperature needed as an supplemental input are reconstructed by the scalar field tomography method using ultraviolet observations from EUVI/STEREO. We will present the reconstructed 3D coronal magnetic field in the range of ∼1.3 R_⊙ obtained by the vector tomographic technique that has been applied to the CoMP data. Title: Growing Transverse Oscillations of a Multistranded Loop Observed by SDO/AIA Authors: Wang, Tongjiang; Ofman, Leon; Davila, Joseph M.; Su, Yang Bibcode: 2012ApJ...751L..27W Altcode: 2012arXiv1204.1376W The first evidence of transverse oscillations of a multistranded loop with growing amplitudes and internal coupling observed by the Atmospheric Imaging Assembly on board the Solar Dynamics Observatory is presented. The loop oscillation event occurred on 2011 March 8, triggered by a coronal mass ejection (CME). The multiwavelength analysis reveals the presence of multithermal strands in the oscillating loop, whose dynamic behaviors are temperature-dependent, showing differences in their oscillation amplitudes, phases, and emission evolution. The physical parameters of growing oscillations of two strands in 171 Å are measured and the three-dimensional loop geometry is determined using STEREO-A/EUVI data. These strands have very similar frequencies, and between two 193 Å strands a quarter-period phase delay sets up. These features suggest the coupling between kink oscillations of neighboring strands and the interpretation by the collective kink mode as predicted by some models. However, the temperature dependence of the multistranded loop oscillations was not studied previously and needs further investigation. The transverse loop oscillations are associated with intensity and loop width variations. We suggest that the amplitude-growing kink oscillations may be a result of continuous non-periodic driving by magnetic deformation of the CME, which deposits energy into the loop system at a rate faster than its loss. Title: Slow-Mode Oscillations of Hot Loops Excited at Flaring Footpoints Authors: Wang, T.; Liu, W.; Ofman, L.; Davila, J. Bibcode: 2012ASPC..456..127W Altcode: 2017arXiv170605427W The analysis of a hot loop oscillation event using SOHO/SUMER, GOES SXI, and RHESSI observations is presented. Damped Doppler shift oscillations were detected in the Fe xix line by SUMER, and interpreted as a fundamental standing slow mode. The evolution of soft X-ray emission from GOES/SXI and hard X-ray sources from RHESSI suggests that the oscillations of a large loop are triggered by a small flare, which may be produced by interaction (local reconnection) of this large loop with a small loop at its footpoint. This study provides clear evidence supporting our early conjecture that the slow-mode standing waves in hot coronal loops are excited by impulsive heating (small or microflares) at the loop's footpoint. Title: Slitless Solar Spectroscopy Authors: Davila, Joseph M. Bibcode: 2012AAS...22020617D Altcode: Spectrographs provide a unique window into plasma parameters in the solar atmosphere. In the corona and elsewhere spectral line profiles have been used to infer microturbulence velocities, Doppler shifts have been used to measure flows, and line ratios have been used to measure temperatures. In fact spectrographs provide the most accurate measurements of plasma parameters such as density, temperature, and flow speed. However, traditionally spectrographic instruments have suffered from the inability to cover large spatial regions of the Sun quickly. To cover an active region sized spatial region, the slit must be rastered over the area of interest with an exposure taken at each pointing location. The raster process can easily take several minutes or longer to cover an active region sized area on the Sun. Because of this long cycle time, the spectra of dynamic events like flares, CME initiations, or transient brightening are obtained only rarely. And even if spectra are obtained they are either taken over an extremely small spatial region, or the spectra are not co-temporal across the raster. Either of these complicates the interpretation of the spectral raster results. Imagers are able to provide high time and spatial resolution images of the full Sun but with limited spectral resolution. The telescopes onboard the Solar Dynamics Observatory (SDO) normally take a full disk solar image every 10 seconds with roughly 1 arcsec spatial resolution. However the spectral resolution of the multilayer imagers on SDO is of order 100 times less than a typical spectrograph. We suggest an alternate reconstruction approach based on tomographic methods with regularization. Results show that the typical Doppler shift and line width error introduced by the reconstruction method is of order a few km/s at 300 A. Title: Propagating Intensity Disturbances in Fan-like Coronal Loops: Flows or Waves? Authors: Wang, T.; Ofman, L.; Davila, J. M. Bibcode: 2012ASPC..455..227W Altcode: 2011arXiv1101.6017W Quasi-periodic intensity disturbances propagating upward along the coronal structure have been extensively studied using EUV imaging observations from SOHO/EIT and TRACE. They were interpreted as either slow mode magnetoacoustic waves or intermittent upflows. In this study we aim at demonstrating that time series of spectroscopic observations are critical to solve this puzzle. Propagating intensity and Doppler shift disturbances in fanlike coronal loops are analyzed in multiple wavelengths using sit-and-stare observations from Hinode/EIS. We find that the disturbances did not cause the blue-wing asymmetry of spectral profiles in the warm (∼1.5 MK) coronal lines. The estimated small line-of-sight velocities also did not support the intermittent upflow interpretation. In the hot (∼2 MK) coronal lines the disturbances did cause the blue-wing asymmetry, but the double fits revealed that a high-velocity minor component is steady and persistent, while the propagating intensity and Doppler shift disturbances are mainly due to variations of the core component, therefore, supporting the slow wave interpretation. However, the cause for blueward line asymmetries remains unclear. Title: High-resolution Solar Imaging with a Photon Sieve Authors: Davila, Joseph M. Bibcode: 2012AAS...22020102D Altcode: Dissipation in the solar corona is expected to occur in extremely thin current sheets of order 1-100 km. Emission from these

current sheets should be visible in coronal EUV emission lines. However, this spatial scale is far below the resolution of existing imaging instruments. Conventional optics cannot be easily manufactured with sufficient surface figure accuracy to obtain the required < 0.1 arcsec resolution. A photon sieve, a diffractive imaging element similar to a Fresnel zone plate, can be manufactured to provide a few 0.001 arcsec resolution, with much more relaxed tolerances than conventional imaging technology. A simple design for a sounding rocket payload is presented that obtains 80 mas (0.080 arcsec) imaging with a 100 mm diameter photon sieve to image Fe XIV 334 and Fe XVI 335. These images will not only show the structure of the corona at a resolution never before obtained, they will also allow a study of the temperature structure in the dissipation region. Title: SDO / AIA Observations of Slow Mode Waves in Coronal Fan Loops Authors: Uritsky, Vadim; Davila, J. M.; Viall, N. M. Bibcode: 2012AAS...22032205U Altcode: We investigate slow mode waves in fan coronal loops observed by the Atmospheric Imaging Assembly (AIA) onboard the Solar Dynamics Observatory spacecraft ( 12 sec cadence, 0.6 arcsec pixels). The warm fan structure studied here was located at the periphery of quiescent active region NOAA AR 11082. A specialized software package has been developed for extracting subvisual modulations of SDO AIA intensity propagating along dynamic loop segments changing their shape and position during the observation. The processing steps include manual tracking of the segment location in time sequences of co-aligned multispectral AIA images, extracting wave-carrying filamentary segments from the surrounding background, constructing position - time diagrams representing temporal evolution of optical brightness along the filaments, and analysis of the obtained wave signatures. The results reveal a persistent wave activity in many fan loop segments characterized by a well-defined frequency and phase speed, with the best signal-to-noise ratio in 171Å and 193Å channels. For some filamentary segments, the wave parameters remained almost constant over the entire observing interval ( 6 hours). The wave parameters varied across the studied structures. The fastest wave fronts exhibited strictly outward propagation while the slower waves could travel both inward and outward. The estimated phase velocity (80-100 km/s) and period (3-4 min) of the most stable outward wave mode are in a good agreement with earlier SOHO EIT and TRACE observations of slow magnetosonic waves in fan loops. The newly observed features include (1) the remarkable coherency of the wave pattern over a course of several hours, and (2) the detailed wave form of the process enabling quantitative analysis of nonlinear propagation and damping effects. No consistent dependence of the wave speed on the distance from the hot core region of AR 11082 was identified, which challenges the traditional picture of traveling magnetoacoustic oscillations in fan loops. Title: Stereo Observations Of Fast Magnetosonic Waves In The Extended Corona Authors: Kwon, Ryun Young; Davila, J. M.; Ofman, L. Bibcode: 2012AAS...22052106K Altcode: Here, we present fast magnetosonic waves propagating across solar radial magnetic fields. STEREO COR1 and EUVI observations showed coronal disturbances associated with flares/CMEs and they propagate in the low solar corona in the form of EIT waves and in the high solar corona (above 1.5 Rs) in the form of density compressions along radial magnetic field lines above EIT wave fronts. It turns out that the coronal disturbances pass through streamers which contain a magnetic separatrix. The wave energy appears to be trapped by the streamers and this leads to stationary fronts at the footpoints of the streamers. Our results suggest that the coronal disturbances associated with flares/CMEs are fast magnetosonic waves propagating with local fast magnetosonic speeds and passing through magnetic separatrices. Moreover, we conclude that EIT waves are ‘real’ fast magnetosonic waves. The speeds of the coronal disturbances are 475 ± 14, 926 ± 19, 1217 ± 24, 1734 ± 48, and 1928 ± 42 km/s at 1.0, 1.6, 2.0, 2.5, and 3.0 Rs, respectively. Using coronal seismology, we estimated magnetic field strengths corresponding to these speeds at the heights and they are 1.81 ± 0.06, 0.98 ± 0.02, 0.70 ± 0.01, 0.55 ± 0.02, and 0.39 ± 0.01 G, respectively. Title: Growing Transverse Oscillations of a Multistranded Loop Observed by SDO/AIA Authors: Wang, Tongjiang; Ofman, L.; Davila, J. M.; Su, Y. Bibcode: 2012AAS...22020717W Altcode: The flare-excited transverse loop oscillations previously observed by TRACE have been mainly interpreted as the global fast kink modes. These oscillations typically have a rapid decay, and their damping mechanism has been a major topic of theoretical studies. In this presentation, we report an unusual case of transverse loop oscillations with growing amplitudes observed by SDO/AIA for the first time. This oscillation event was triggered by a flare associated with a CME above the limb. The multiwavelength analysis reveals that the loop consists of multithermal strands and their dynamical behaviors are temperature-dependent. These strands have very similar oscillation frequencies and appear to oscillate in-phase or in a quarter-period phase delay. These features suggest the coupling between kink oscillations of neighboring strands and the interpretation by the collective kink mode as predicted by some models. The transverse loop oscillations are also associated with intensity and loop width variations. We determine the trigger of the oscillation and measure the 3-D loop geometry using STEREO/EUVI-A data. The possible mechanisms that can excite the growing kink oscillations will be discussed. Title: Impulsively Driven Waves And Flows In Coronal Active Regions Authors: Ofman, Leon; Wang, T.; Davila, J. M.; Liu, W. Bibcode: 2012AAS...22032204O Altcode: Recent SDO/AIA and Hinode EIS observations indicate that both (super) fast and slow magnetosonic waves are present in active region (AR) magnetic structures. Evidence for fast (100-300 km/s) impulsive flows is found in spectroscopic and imaging observations of AR loops. The super-fast waves were observed in magnetic funnels of ARs. The observations suggest that waves and flow are produced by impulsive events, such as (micro) flares. We have performed three-dimensional magnetohydrodynamic (3D MHD) simulations of impulsively generated flows and waves in coronal loops of a model bi-polar active region (AR). The model AR is initiated with a dipole magnetic field and gravitationally stratified density, with impulsively driven flow at the coronal base of the AR in localized magnetic field structures. We model the excitation of the flows in hot (6MK) and cold (1MK) active region plasma, and find slow and fast magnetosonic waves produced by these events. We also find that high-density (compared to surrounding corona) loops are produced as a result of the upflows. We investigate the parametric dependence between the properties of the impulsive flows and the waves. The results of the 3D MHD modeling study supports the conjecture that slow magnetosonic waves are often produced by impulsive upflows along the magnetic field, and fast magnetosonic waves can result from impulsive transverse field line perturbations associated with reconnection events. The waves and flows can be used for diagnostic of AR structure and dynamics. Title: Multiscale Dynamics of Interacting Solar Structures Authors: Uritsky, Vadim; Davila, J. M. Bibcode: 2012AAS...22020113U Altcode: Sun is an inherently complex and multiscale system which continues to challenge theorists and experimentalists alike. Coronal holes with scales typically on the order of a solar radius are the sources of high speed solar wind streams, and coronal active region magnetic loops, with typical scales of 10,000 km, exhibit somewhat steady heating. Direct heating of the coronal plasma, unresolved in current instruments, takes place at a typical ohmic dissipation scale in the corona, which is likely to be as small as 100 km. The Sun also exhibits a broad range of temporal scales. The largest features are observed to last for months. Coronal holes and coronal streamers can persist for several 27-day solar rotations with little change, while solar flares release a vast amount of energy essentially doubling the solar luminosity for a brief period of a few minutes. It is widely believed that the ultimate power source for all energy release processes in the upper solar atmosphere is convection at the solar surface mediated by magnetic field. Multiscale and nonlocal nature of this process often prevents its direct identification. Here, we present a new data analysis framework capable of identifying multiscale spatiotemporal causality between the photospheric magnetic field and coronal dissipation. The method involves spatiotemporal tracking of photospheric magnetic structures and coronal heating events, and their cross-correlation analysis based on a generalized correlation integral algorithm. The algorithms use no a priori assumptions regarding the intrinsic spatial and temporal interaction scales. The performance of the developed approach in identifying unstable magnetic configurations controlling coronal dissipation and heating is demonstrated on a variety of solar conditions, including quiet Sun and a solar active region in flaring and quiescent states. Title: Spectroscopic Diagnosis of Propagating Disturbances in Coronal Loops: Waves or flows? Authors: Wang, T.; Ofman, L.; Davila, J. M. Bibcode: 2012ASPC..456...91W Altcode: The analysis of multiwavelength properties of propagating disturbances (PDs) using Hinode/EIS observations is presented. Quasi-periodic PDs were mostly interpreted as slow magnetoacoustic waves in early studies, but recently suggested to be intermittent upflows of the order of 50-150 km s-1 based on the Red-Blue (RB) asymmetry analysis of spectral line profiles. Using the forward models, velocities of the secondary component derived from the RB analysis are found significantly overestimated due to the saturation effect when its offset velocities are smaller than the Gaussian width. We developed a different method to examine spectral features of the PDs. This method is assuming that the excessive emission of the PD profile against the background (taken as that prior to the PD) is caused by a hypothetic upflow. The derived LOS velocities of the flow are on the order of 10-30 km s-1 from the warm (1-1.5 MK) coronal lines, much smaller than those inferred from the RB analysis. This result does not support the flow interpretation but favors of the early wave interpretation. Title: Understanding Solar Energetic Events Using the Next Generation Coronagraph: High-resolution Imaging with Diagnostic Capability Authors: Davila, Joseph M. Bibcode: 2012AAS...22042401D Altcode: What is the mechanism for CME initiation? Soon for the first time coronagraphs will image and resolve

the magnetic field structural changes in the Corona that lead to the onset of

Coronal Mass Ejections (CMEs). The data provided by these instruments will for the first time provide a time sequence of high-resolution images showing the looptop regions where reconnection leading to flares and the acceleration of energetic particles takes place. These data will enable the determination of the CME initiation mechanism, without which it is impossible

to understand the physics of the triggering of energetic events on the Sun. The determination of the cause of flare onset would be major step toward

advance forecasting of CME’s that drive the radiation environment in near Earth

space, and the solar system in general. These data will also show the magnetic connectivity of the low corona out to the orbit of Solar Probe Plus and Solar Orbiter. Title: Erratum to: Relation Between Type II Bursts and CMEs Inferred from STEREO Observations Authors: Gopalswamy, N.; Thompson, W. T.; Davila, J. M.; Kaiser, M. L.; Yashiro, S.; Mäkelä, P.; Michalek, G.; Bougeret, J. -L.; Howard, R. A. Bibcode: 2012SoPh..277..459G Altcode: 2011SoPh..tmp..421G; 2011SoPh..tmp..425G No abstract at ADS Title: Solar magnetism eXplorer (SolmeX). Exploring the magnetic field in the upper atmosphere of our closest star Authors: Peter, Hardi; Abbo, L.; Andretta, V.; Auchère, F.; Bemporad, A.; Berrilli, F.; Bommier, V.; Braukhane, A.; Casini, R.; Curdt, W.; Davila, J.; Dittus, H.; Fineschi, S.; Fludra, A.; Gandorfer, A.; Griffin, D.; Inhester, B.; Lagg, A.; Landi Degl'Innocenti, E.; Maiwald, V.; Sainz, R. Manso; Martínez Pillet, V; Matthews, S.; Moses, D.; Parenti, S.; Pietarila, A.; Quantius, D.; Raouafi, N. -E.; Raymond, J.; Rochus, P.; Romberg, O.; Schlotterer, M.; Schühle, U.; Solanki, S.; Spadaro, D.; Teriaca, L.; Tomczyk, S.; Trujillo Bueno, J.; Vial, J. -C. Bibcode: 2012ExA....33..271P Altcode: 2011arXiv1108.5304P; 2011ExA...tmp..134P The magnetic field plays a pivotal role in many fields of Astrophysics. This is especially true for the physics of the solar atmosphere. Measuring the magnetic field in the upper solar atmosphere is crucial to understand the nature of the underlying physical processes that drive the violent dynamics of the solar corona—that can also affect life on Earth. SolmeX, a fully equipped solar space observatory for remote-sensing observations, will provide the first comprehensive measurements of the strength and direction of the magnetic field in the upper solar atmosphere. The mission consists of two spacecraft, one carrying the instruments, and another one in formation flight at a distance of about 200 m carrying the occulter to provide an artificial total solar eclipse. This will ensure high-quality coronagraphic observations above the solar limb. SolmeX integrates two spectro-polarimetric coronagraphs for off-limb observations, one in the EUV and one in the IR, and three instruments for observations on the disk. The latter comprises one imaging polarimeter in the EUV for coronal studies, a spectro-polarimeter in the EUV to investigate the low corona, and an imaging spectro-polarimeter in the UV for chromospheric studies. SOHO and other existing missions have investigated the emission of the upper atmosphere in detail (not considering polarization), and as this will be the case also for missions planned for the near future. Therefore it is timely that SolmeX provides the final piece of the observational quest by measuring the magnetic field in the upper atmosphere through polarimetric observations. Title: Growing and coupled transverse oscillations of a multistranded loop observed by SDO/AIA Authors: Wang, Tongjiang; Ofman, Leon; Davila, Joseph M.; Su, Yang Bibcode: 2012decs.confE..51W Altcode: We report the first evidence of transverse oscillations of a multistranded loop with growing amplitudes and internal coupling observed by SDO/AIA. The loop oscillations were triggered by a flare-CME event occurring in an active region visible at the limb. The multiwavelength analysis reveals the temperature dependence of multiple strands, which show differences in their oscillation amplitudes, phases and emission evolution. The physical parameters of growing transverse oscillations in 171A band are measured and the 3-D loop geometry is determined using STEREO/EUVI-A data. The strands have very similar oscillation frequencies and appear to oscillate in-phase or in a quarter-period phase delay. The observed oscillation properties of the loop strands agree with theoretically expected coupling between neighboring strands of a loop that undergoes a global kink mode oscillation. The transverse loop oscillations are also associated with intensity and loop width variations. We discuss the possible mechanisms that can excite the kink oscillations with growing amplitudes, and their associations with intensity and loop width variations. Title: Modeling waves, flows, and instabilities produced by impulsive events in coronal active regions Authors: Ofman, L.; Liu, W.; Wang, T. J.; Davila, J. M.; Thompson, B. J. Bibcode: 2012decs.confE..73O Altcode: Recent high-resolution observations by SDO/AIA combined with spectral data from Hinode provide insights into the properties of MHD waves, flows, and instabilities in coronal active region plasma and their connection with impulsive energy release. Shear flow driven instabilities, such as the Kelvin-Helmholtz (KH) instability were only recently detected in detail in the corona. I will present recent results of 3D MHD models of slow and fast magnetosonic waves in active regions excited by jets and quasi-periodic flows driven by micro-flares at loops' footpoints. I will discuss models of super-fast magnetosonic waves detected recently by SDO/AIA. I will also discuss models of global (EIT) waves, and KH instabilities driven by CMEs. The relations between waves, flows, instabilities, and impulsive events such as flares and CMEs are becoming apparent thanks to the combination of observational data analysis and the 3D MHD modeling. Understanding these relations is useful for coronal seismology and for tracing the flow of energy from the transition region to the corona. Title: White Light Coronal Velocity and Temperature Diagnostics Authors: Davila, Joseph M.; Reginald, Nelson; St. Cyr, O. C. Bibcode: 2012decs.confE..55D Altcode: During the March 2006 total solar eclipse we conducted an imaging experiment using the Imaging Spectrograph of Coronal Electrons (ISCORE) to determine the coronal electron temperature and its radial flow speed in the low solar corona. This technique required taking images of the solar eclipse through four broadband filters centered at 385.0, 398.7, 410.0 and 423.3 nm. The K-coronal temperature is determined from intensity ratios from the 385.0 and 410.0 nm filters, and the K-coronal radial flow speed is determined from intensity ratios from the 398.7 and 423.3 nm filters. The theoretical model for this technique assumes a symmetric corona devoid of any features like streamers that might alter the coronal symmetry. The model also requires an isothermal temperature and a uniform outflow speed all along the line of sight. We will call this the Constant Parameter Thomson Scattering Model (CPTSM). The latter assumption may sound unreasonable but in the symmetric corona with rapid fall of the electron density with height in the solar corona, the major contributions to the K-coronal intensity along a given line of sight comes from the plasma properties in the vicinity of the plane of the sky. But the pressing question is how is the derived plasma properties by ISCORE compare with the nature of the true corona. For this we turn to the CORHEL model by Predictive Science Inc. which used magnetogram data to create a realistic model of the solar corona that are made available through the Community Coordinated Modeling Center (CCMC) at GSFC. That team has consistently produced the expected coronal image days prior to many total eclipses where the major coronal features from their model matched actual coronal image on the day of the eclipse. Using the CORHEL model data we have calculated the K-coronal intensities at 385.0, 398.7, 410.0 and 423.3 nm using the electron density, plasma temperature (assumed to be electron temperature) and the flow speeds of the plasma along the line of sight in the CORHEL model and have calculated the temperature and radial flow speed sensitive intensity ratios. Next we identify the isothermal electron temperature and the radial flow speed in the CPTSM model that would match the temperature sensitive and radial flow speed sensitive intensity ratios from the CORHEL model and compare the CPTSM temperature and flow speed values with the corresponding values in the CORHEL model in the plane of the sky. These comparisons were made for Carrington Rotation 1977 with the CORHEL model of the solar corona rotated in intervals of 45 degrees with respect to the observer located at 1 AU. The average of the difference between the electron temperatures and the radial flow speed at 5 solar radii in the East-West direction were (underestimated by 0.02 MK or an error of 1.7%) and (overestimated by 22.km/sec or an error of 18%), respectively and in the South-North direction were (underestimated by 0.04 MK or an error of 3.2%) and (overestimated by 42 km/sec or an error of 21%), respectively. Title: Multiscale Dynamics of Solar Magnetic Structures Authors: Uritsky, Vadim M.; Davila, Joseph M. Bibcode: 2012ApJ...748...60U Altcode: 2011arXiv1111.5053U Multiscale topological complexity of the solar magnetic field is among the primary factors controlling energy release in the corona, including associated processes in the photospheric and chromospheric boundaries. We present a new approach for analyzing multiscale behavior of the photospheric magnetic flux underlying these dynamics as depicted by a sequence of high-resolution solar magnetograms. The approach involves two basic processing steps: (1) identification of timing and location of magnetic flux origin and demise events (as defined by DeForest et al.) by tracking spatiotemporal evolution of unipolar and bipolar photospheric regions, and (2) analysis of collective behavior of the detected magnetic events using a generalized version of the Grassberger-Procaccia correlation integral algorithm. The scale-free nature of the developed algorithms makes it possible to characterize the dynamics of the photospheric network across a wide range of distances and relaxation times. Three types of photospheric conditions are considered to test the method: a quiet photosphere, a solar active region (NOAA 10365) in a quiescent non-flaring state, and the same active region during a period of M-class flares. The results obtained show (1) the presence of a topologically complex asymmetrically fragmented magnetic network in the quiet photosphere driven by meso- and supergranulation, (2) the formation of non-potential magnetic structures with complex polarity separation lines inside the active region, and (3) statistical signatures of canceling bipolar magnetic structures coinciding with flaring activity in the active region. Each of these effects can represent an unstable magnetic configuration acting as an energy source for coronal dissipation and heating. Title: Three-Dimensional MHD Models of Waves and Flows in Coronal Active Region Loops Authors: Ofman, L.; Wang, T.; Davila, J. M. Bibcode: 2011AGUFMSH34B..02O Altcode: Recent observations show that slow magnetosonic waves are present in active region loops, and are often associated with subsonic up-flows of coronal material. In order to study the relation between up-flows and waves we develop a 3D MHD model of an idealized bi-polar active region with flows in coronal loops. The model is initiated with a dipole magnetic field and gravitationally stratified isothermal atmosphere. To model the effects of flares, coronal material is injected in small-scale regions at the base of the model active region. The up-flows have sub-sonic speeds of ∼100 km/s and are steady or periodic, producing higher density loops by filling magnetic flux-tubes with injected material. We find that the up-flows produce fast and slow magnetosonic waves that propagate in the coronal loops. We perform a parametric study of up-flow magnitude and periodicity, and the relation with the resulting waves. As expected, we find that the up-flow speed decreases with loop height due to the diverge of the flux tubes, while the slow magnetosonic speed is independent of height. When the amplitude of the driving pulses is increased above the sound speed, we find that slow shocks are produced in the loops. Using the results of the 3D MHD model we show that observed slow magnetosonic waves in active region loops can be driven by impulsive flare-produced up-flows at the transition region/corona interface of active regions. Title: Propagating low-frequency waves in coronal streamers observed by STEREO COR1 Authors: Kwon, R.; Davila, J. M.; Ofman, L. Bibcode: 2011AGUFMSH43C1981K Altcode: Compressional and transverse propagating waves high above the solar surface may play an important role in heating and accelerating the solar wind. Waves with periods of about an hour were detected in streamers in the past using SOHO/LASCO observations. STEREO COR1 provides us with the coronagraph (~4 solar radius) with high temporal resolution (5 min time cadence) so that it allows us to study low frequency waves systematically and address line-of-sight ambiguity. We present a method to detect the periodic oscillations along coronal streamers observed by STEREO COR1 and to determine the wavelength, period and phase speed with wavelet analysis. Further, we discuss physical implications of our results and the possible origin of the waves we found. Title: Underflight Calibration of SOHO/CDS and Hinode/EIS with EUNIS-07 Authors: Wang, Tongjiang; Thomas, Roger J.; Brosius, Jeffrey W.; Young, Peter R.; Rabin, Douglas M.; Davila, Joseph M.; Del Zanna, Giulio Bibcode: 2011ApJS..197...32W Altcode: 2011arXiv1109.6598W Flights of Goddard Space Flight Center's Extreme Ultraviolet Normal Incidence Spectrograph (EUNIS) sounding rocket in 2006 and 2007 provided updated radiometric calibrations for Solar and Heliospheric Observatory/Coronal Diagnostic Spectrometer (SOHO/CDS) and Hinode/Extreme Ultraviolet Imaging Spectrometer (Hinode/EIS). EUNIS carried two independent imaging spectrographs covering wavebands of 300-370 Å in first order and 170-205 Å in second order. After each flight, end-to-end radiometric calibrations of the rocket payload were carried out in the same facility used for pre-launch calibrations of CDS and EIS. During the 2007 flight, EUNIS, SOHO/CDS, and Hinode/EIS observed the same solar locations, allowing the EUNIS calibrations to be directly applied to both CDS and EIS. The measured CDS NIS 1 line intensities calibrated with the standard (version 4) responsivities with the standard long-term corrections are found to be too low by a factor of 1.5 due to the decrease in responsivity. The EIS calibration update is performed in two ways. One uses the direct calibration transfer of the calibrated EUNIS-07 short wavelength (SW) channel. The other uses the insensitive line pairs, in which one member was observed by the EUNIS-07 long wavelength (LW) channel and the other by EIS in either the LW or SW waveband. Measurements from both methods are in good agreement, and confirm (within the measurement uncertainties) the EIS responsivity measured directly before the instrument's launch. The measurements also suggest that the EIS responsivity decreased by a factor of about 1.2 after the first year of operation (although the size of the measurement uncertainties is comparable to this decrease). The shape of the EIS SW response curve obtained by EUNIS-07 is consistent with the one measured in laboratory prior to launch. The absolute value of the quiet-Sun He II 304 Å intensity measured by EUNIS-07 is consistent with the radiance measured by CDS NIS in quiet regions near the disk center and the solar minimum irradiance recently obtained by CDS NIS and the Solar Dynamics Observatory/Extreme Ultraviolet Variability Experiment. Title: Determination of Non-thermal Velocity Distributions from SERTS Linewidth Observations Authors: Coyner, Aaron J.; Davila, Joseph M. Bibcode: 2011ApJ...742..115C Altcode: Non-thermal velocities obtained from the measurement of coronal Extreme Ultraviolet (EUV) linewidths have been consistently observed in solar EUV spectral observations and have been theorized to result from many plausible scenarios including wave motions, turbulence, or magnetic reconnection. Constraining these velocities can provide a physical limit for the available energy resulting from unresolved motions in the corona. We statistically determine a series of non-thermal velocity distributions from linewidth measurements of 390 emission lines from a wide array of elements and ionization states observed during the Solar Extreme Ultraviolet Research Telescope and Spectrograph 1991-1997 flights covering the spectral range 174-418 Å and a temperature range from 80,000 K to 12.6 MK. This sample includes 248 lines from active regions, 101 lines from quiet-Sun regions, and 41 lines were observed from plasma off the solar limb. We find a strongly peaked distribution corresponding to a non-thermal velocity of 19-22 km s-1 in all three of the quiet-Sun, active region, and off-limb distributions. For the possibility of Alfvén wave resonance heating, we find that velocities in the core of these distributions do not provide sufficient energy, given typical densities and magnetic field strengths for the coronal plasma, to overcome the estimated coronal energy losses required to maintain the corona at the typical temperatures working as the sole mechanism. We find that at perfect efficiency 50%-60% of the needed energy flux can be produced from the non-thermal velocities measured. Title: High-resolution solar imaging with a photon sieve Authors: Davila, J. M. Bibcode: 2011AGUFMSH33B2053D Altcode: Dissipation in the solar corona is expected to occur in extremely thin current sheets of order 1-100 km. Emission from these current sheets should be visible in coronal EUV emission lines. However, this spatial scale is far below the resolution of existing imaging instruments, because conventional optics cannot be easily manufactured with sufficient surface figure accuracy to obtain the required < 0.1 arcsec resolution. A photon sieve, a diffractive imaging element, can be manufactured to provide a few 10-3 arcsec resolution, with much more relaxed tolerances than conventional imaging technology. A simple design for a sounding rocket payload is presented that obtain 80 mArcsec imaging with a 100 mm diameter photon sieve to image Fe XIV 334 and Fe XVI 335. These images will not only show the structure of the corona at a resolution never before obtained, they will also allow a study of the temperature structure. Title: Technique to Measure the Coronal Electron Temperature and Radial Flow Speed Authors: Reginald, N. L.; Davila, J. M.; St Cyr, O. C. Bibcode: 2011AGUFMSH43F..02R Altcode: During the March 2006 total solar eclipse we conducted an imaging experiment using the Imaging Spectrograph of Coronal Electrons (ISCORE) to determine the coronal electron temperature and its radial flow speed in the low solar corona. This technique required taking images of the solar eclipse through four broadband filters centered at 385.0, 398.7, 410.0 and 423.3 nm. The K-coronal temperature is determined from intensity ratios from the 385.0 and 410.0 nm filters, and the K-coronal radial flow speed is determined from intensity ratios from the 398.7 and 423.3 nm filters. The theoretical model for this technique assumes a symmetric corona devoid of any features like streamers that might alter the coronal symmetry. The model also requires an isothermal temperature and a uniform outflow speed all along the line of sight. We will call this the Constant Parameter Thomson Scattering Model (CPTSM). The latter assumption may sound unreasonable but in the symmetric corona with rapid fall of the electron density with height in the solar corona, the major contributions to the K-coronal intensity along a given line of sight comes from the plasma properties in the vicinity of the plane of the sky. But the pressing question is how is the derived plasma properties by ISCORE compare with the nature of the true corona. For this we turn to the CORHEL model by Predictive Science Inc. which used magnetogram data to create a realistic model of the solar corona that are made available through the Community Coordinated Modeling Center (CCMC) at GSFC. That team has consistently produced the expected coronal image days prior to many total eclipses where the major coronal features from their model matched actual coronal image on the day of the eclipse. Using the CORHEL model data we have calculated the K-coronal intensities at 385.0, 398.7, 410.0 and 423.3 nm using the electron density, plasma temperature (assumed to be electron temperature) and the flow speeds of the plasma along the line of sight in the CORHEL model and have calculated the temperature and radial flow speed sensitive intensity ratios. Next we identify the isothermal electron temperature and the radial flow speed in the CPTSM model that would match the temperature sensitive and radial flow speed sensitive intensity ratios from the CORHEL model and compare the CPTSM temperature and flow speed values with the corresponding values in the CORHEL model in the plane of the sky. These comparisons were made for Carrington Rotation 1977 with the CORHEL model of the solar corona rotated in intervals of 45 degrees with respect to the observer located at 1 AU. The average of the difference between the electron temperatures and the radial flow speed at 5 solar radii in the East-West direction were (underestimated by 0.02 MK or an error of 1.7%) and (overestimated by 22.km/sec or an error of 18%), respectively and in the South-North direction were (underestimated by 0.04 MK or an error of 3.2%) and (overestimated by 42 km/sec or an error of 21%), respectively. Title: Multi-scale Energy Dissipation on the Sun Authors: Davila, J. M.; Uritsky, V. M. Bibcode: 2011AGUFMSH51C2021D Altcode: The outer atmosphere of the Sun is powered by the release of energy over a broad range of spatial and temporal scales. Coronal holes with scales typically on the order of a solar radius (6.95 x 10^5 km) are the sources of high speed solar wind streams, and coronal active region magnetic loops, with typical scales of 10,000 km, exhibit somewhat steady heating. Direct heating of the coronal plasma, unresolved in current instruments, takes place at a typical ohmic dissipation scale in the corona, which is likely to be as small as 100 km. The Sun also exhibits a broad range of temporal scales. The largest features are observed to last for months. Coronal holes and coronal streamers can persist for several 27-day solar rotations with little change. Solar flares release a vast amount of energy essentially doubling the solar luminosity for a brief period of a few minutes. Within these events time variability is observed down to a few milli-seconds. It is widely believed that the ultimate power source for all energy release processes in the upper solar atmosphere is convection at the solar surface. Convective flows (1) generate the magnetic field in the convection zone of the Sun, and (2) stress the field generating electrical currents allowing the buildup of energy in localized regions over time. How is the broad range of scales observed on the Sun coupled together? How is energy converted from local dissipation sites into the diffuse corona observed? How are the upper atmospheric layers, the corona and chromospheres, coupled to convective motions in the photosphere, the presumed energy source? How do these processes drive hazardous space weather events which exhibit power-law statistics characteristic of dynamical systems at criticality, and how good are our chances to predict such events considering their inherent multiscale origin? These are significant open questions that remain to be answered. Title: Vector Tomography Inversion for the 3D Coronal Magnetic Field Based on CoMP data Authors: Kramar, M.; Lin, H.; Tomczyk, S.; Inhester, B.; Davila, J. M. Bibcode: 2011AGUFMSH43B1948K Altcode: Magnetic fields in the solar corona dominates the gas pressure and therefore determine the static and dynamic properties of the corona. Direct measurement of the coronal magnetic field is one of the most challenging problems in observational solar astronomy and recently a significant progress has been achieved here with deployment of the HAO Coronal Multichannel Polarimeter (CoMP). The instrument provides polarization measurements of Fe XIII 10747 A forbidden line emission. The observed polarization depends on magnetic field through the Hanle and Zeeman effects. However, because the coronal measurements are integrated over line-of-site (LOS), it is impossible to derive the configuration of the coronal magnetic field from a single observation (from a single viewing direction). The vector tomography techniques based on measurements from several viewing directions has the potential to resolve the 3D coronal magnetic field structure over LOS. Because of the non-linear character of the Hanle effect, the reconstruction result based on such data is not straightforward and depends on the particular coronal field configuration. Therefore we study here what is the sensitivity of the vector tomographic inversion to sophisticated (MHD) coronal magnetic field models. For several important cases of magnetic field configuration, it has been found that even just Stokes-Q and -U data (supplied with 3D coronal density and temperature) can be used in vector tomography to provide a realistic 3D coronal magnetic field configuration. This vector tomograpic technique is applied to CoMP data. Title: United Nations Basic Space Science Initiative: 2010 Status Report on the International Space Weather Initiative Authors: Gadimova, S.; Haubold, H. J.; Danov, D.; Georgieva, K.; Maeda, G.; Yumoto, K.; Davila, J. M.; Gopalswamy, N. Bibcode: 2011SunGe...6....7G Altcode: 2011arXiv1108.2247G The UNBSSI is a long-term effort for the development of astronomy and space science through regional and international cooperation in this field on a worldwide basis. A series of workshops on BSS was held from 1991 to 2004 (India 1991, Costa Rica and Colombia 1992, Nigeria 1993, Egypt 1994, Sri Lanka 1995, Germany 1996, Honduras 1997, Jordan 1999, France 2000, Mauritius 2001, Argentina 2002, and China 2004) Pursuant to resolutions of the United Nations Committee on the Peaceful Uses of Outer Space (UNCOPUOS) and its Scientific and Technical Subcommittee, since 2005, these workshops focused on the International Heliophysical Year 2007 (UAE 2005, India 2006, Japan 2007, Bulgaria 2008, Ro Korea 2009) Starting in 2010, the workshops focus on the International Space Weather Initiative (ISWI) as recommended in a three-year-work plan as part of the deliberations of UNCOPUOS (www.iswi-secretariat.org/). Workshops on the ISWI have been scheduled to be hosted by Egypt in 2010 for Western Asia, Nigeria in 2011 for Africa, and Ecuador in 2012 for Latin America and the Caribbean. Currently, fourteen IHY/ISWI instrument arrays with more than five hundred instruments are operational in ninety countries. Title: Earth-Affecting Solar Causes Observatory (EASCO): a mission at the Sun-Earth L5 Authors: Gopalswamy, Nat; Davila, Joseph M.; Auchère, Frédéric; Schou, Jesper; Korendyke, Clarence M.; Shih, Albert; Johnston, Janet C.; MacDowall, Robert J.; Maksimovic, Milan; Sittler, Edward; Szabo, Adam; Wesenberg, Richard; Vennerstrom, Suzanne; Heber, Bernd Bibcode: 2011SPIE.8148E..0ZG Altcode: 2011SPIE.8148E..30G; 2011arXiv1109.2929G Coronal mass ejections (CMEs) and corotating interaction regions (CIRs) as well as their source regions are important because of their space weather consequences. The current understanding of CMEs primarily comes from the Solar and Heliospheric Observatory (SOHO) and the Solar Terrestrial Relations Observatory (STEREO) missions, but these missions lacked some key measurements: STEREO did not have a magnetograph; SOHO did not have in-situ magnetometer. SOHO and other imagers such as the Solar Mass Ejection Imager (SMEI) located on the Sun-Earth line are also not well-suited to measure Earth-directed CMEs. The Earth-Affecting Solar Causes Observatory (EASCO) is a proposed mission to be located at the Sun-Earth L5 that overcomes these deficiencies. The mission concept was recently studied at the Mission Design Laboratory (MDL), NASA Goddard Space Flight Center, to see how the mission can be implemented. The study found that the scientific payload (seven remote-sensing and three in-situ instruments) can be readily accommodated and can be launched using an intermediate size vehicle; a hybrid propulsion system consisting of a Xenon ion thruster and hydrazine has been found to be adequate to place the payload at L5. Following a 2-year transfer time, a 4-year operation is considered around the next solar maximum in 2025. Title: High-resolution solar imaging with a photon sieve Authors: Davila, Joseph M. Bibcode: 2011SPIE.8148E..0OD Altcode: 2011SPIE.8148E..22D Dissipation in the solar corona is expected to occur in extremely thin current sheets of order 1-100 km. Emission from these current sheets should be visible in coronal EUV emission lines. However, this spatial scale is far below the resolution of existing imaging instruments. Conventional optics cannot be easily manufactured with sufficient surface figure accuracy to obtain the required < 0.1 arcsec resolution. A photon sieve, a diffractive imaging element similar to a Fresnel zone plate, can be manufactured to provide a few 0.001 arcsec resolution, with much more relaxed tolerances than conventional imaging technology. A simple design for a sounding rocket payload is presented that obtains 80 mas (0.080 arcsec) imaging with a 100 mm diameter photon sieve to image Fe XIV 334 and Fe XVI 335. These images will not only show the structure of the corona at a resolution never before obtained, they will also allow a study of the temperature structure in the dissipation region. Title: New GPS constraints on active deformation along the Africa-Iberia plate boundary Authors: Koulali, A.; Ouazar, D.; Tahayt, A.; King, R. W.; Vernant, P.; Reilinger, R. E.; McClusky, S.; Mourabit, T.; Davila, J. M.; Amraoui, N. Bibcode: 2011E&PSL.308..211K Altcode: We use velocities from 65 continuous stations and 31 survey-mode GPS sites as well as kinematic modeling to investigate present day deformation along the Africa-Iberia plate boundary zone in the western Mediterranean region. The GPS velocity field shows southwestward motion of the central part of the Rif Mountains in northern Morocco with respect to Africa varying between 3.5 and 4.0 mm/yr, consistent with prior published results. Stations in the southwestern part of the Betic Mountains of southern Spain move west-southwest with respect to Eurasia (∼ 2-3 mm/yr). The western component of Betics motion is consistent with partial transfer of Nubia-Eurasia plate motion into the southern Betics. The southward component of Betics motion with respect to Iberia is kinematically consistent with south to southwest motion of the Rif Mountains with respect to Africa. We use block modeling, constrained by mapped surface faults and seismicity to estimate the geometry and rates of strain accumulation on plate boundary structures. Our preferred plate boundary geometry includes one block between Iberia and Africa including the SW Betics, Alboran Sea, and central Rif. This geometry provides a good fit to the observed motions, suggesting a wide transpressive boundary in the westernmost Mediterranean, with deformation mainly accommodated by the Gloria-Azores fault system to the West and the Rif-Tell lineament to the East. Block boundaries encompass aspects of earlier interpretations suggesting three main deformation styles: (i) extension along the NE-SW trending Trans-Alboran shear zone, (ii) dextral strike-slip in the Betics corresponding to a well defined E-W seismic lineament, and (iii) right lateral strike-slip motion extending West to the Azores and right-lateral motion with compression extending East along the Algerian Tell. We interpret differential motion in the Rif-Alboran-Betic system to be driven both by surface processes related the Africa-Eurasia oblique convergence and sub-crustal dynamic processes associated with the long history of subduction of the Neotethys ocean lithosphere. The dextral slip identified in the Betic Mountains in Southern Spain may be related to the offshore fault that produced the Great 1755 Lisbon Earthquake, and as such may represent a significant seismic hazard for the West Mediterranean region. Title: STEREO SECCHI COR1-A/B Intercalibration at 180° Separation Authors: Thompson, W. T.; Davila, J. M.; St. Cyr, O. C.; Reginald, N. L. Bibcode: 2011SoPh..272..215T Altcode: 2011SoPh..tmp..204T; 2011SoPh..tmp..324T; 2011SoPh..tmp..273T; 2011SoPh..tmp..299T The twin Solar Terrestrial Relations Observatory (STEREO) spacecraft reached a separation angle of 180° on 6 February 2011. This provided a unique opportunity to test the intercalibration between the Sun-Earth Connection Coronal and Heliospheric Investigation (SECCHI) telescopes on both spacecraft for areas above the limb. So long as the corona is optically thin, at 180° separation each spacecraft sees the same corona from opposite directions. Thus, the data should appear as mirror images of each other. We report here on the results of the comparison of the images taken by the inner coronagraph (COR1) on the STEREO-Ahead and -Behind spacecraft in the hours when the separation was close to 180°. We find that the intensity values seen by the two telescopes agree with each other to a high degree of accuracy. This validates both the radiometric intercalibration between the COR1 telescopes, and the method used to remove instrumental background from the images. The relative error between COR1-A and COR1-B is found to be less than 10−9B/B over most of the field-of-view, growing to a few ×10−9B/B for the brighter pixels near the edge of the occulter. The primary source of error is the background determination. We also report on the analysis of star observations which show that the absolute radiometric calibration of either COR1 telescope has not changed significantly since launch. Title: Analysis and study of the in situ observation of the June 1st 2008 CME by STEREO Authors: Nieves-Chinchilla, T.; Gómez-Herrero, R.; Viñas, A. F.; Malandraki, O.; Dresing, N.; Hidalgo, M. A.; Opitz, A.; Sauvaud, J. -A.; Lavraud, B.; Davila, J. M. Bibcode: 2011JASTP..73.1348N Altcode: In this work we present a combined study of the counterpart of the coronal mass ejection (CME) of June 1st of 2008 in the interplanetary medium. This event has been largely studied because of its peculiar initiation and its possible forecasting consequences for space weather. We show an in situ analysis (on days June 6th-7th of 2008) of the CME in the interplanetary medium in order to shed some light on the propagation and evolution mechanisms of the interplanetary CME (ICME). The goals of this work are twofold: gathering the whole in situ data from PLASTIC and IMPACT onboard STEREO B in order to provide a complete characterization of the ICME, and to present a model where the thermal plasma pressure is included. The isolated ICME features show a clear forward shock which we identify as an oblique forward fast shock accelerating ions to a few-hundred keV during its passage. Following the shock, a flux rope is easily defined as a magnetic cloud (MC) by the magnetic field components and magnitude, and the low proton plasma-β. During the spacecraft passage through the MC, the energetic ion intensity shows a pronounced decrease, suggesting a closed magnetic topology, and the suprathermal electron population shows a density and temperature increase, demonstrating the importance of the electrons in the MC description. The in situ evidence suggests that there is no direct magnetic connection between the forward shock and the MC, and the characteristics of the reverse shock determined suggest that the shock pair is a consequence of the propagation of the ICME in the interplanetary medium. The energetic ions measured by the SEPT instrument suggest that their enhancement is not related to any solar event, but is solely due to the interplanetary shock consistent with the fact that no flares are observed on the Sun. The changes in the polarity of the interplanetary magnetic field in the vicinity of the ICME observed by electron PADs from SWEA are in accordance with the idea that the CME originated along a neutral line over the quiet Sun.The magnetic cloud model presented in this work provides the plasma pressure as a new factor to consider in the study of the expansion and evolution of CMEs in the interplanetary medium. This model could provide a new understanding of the Sun-Earth connection because of the important role that the plasma plays in the eruption of the CME in the solar corona and the reconnection process carried out with the Earth's magnetosphere. Title: Electron Temperatures and Flow Speeds of the Low Solar Corona: MACS Results from the Total Solar Eclipse of 29 March 2006 in Libya Authors: Reginald, Nelson L.; Davila, Joseph M.; St. Cyr, O. C.; Rabin, Douglas M.; Guhathakurta, Madhulika; Hassler, Donald M.; Gashut, Hadi Bibcode: 2011SoPh..270..235R Altcode: 2011SoPh..tmp...68R; 2011SoPh..tmp...48R An experiment was conducted in conjunction with the total solar eclipse on 29 March 2006 in Libya to measure both the electron temperature and its flow speed simultaneously at multiple locations in the low solar corona by measuring the visible K-coronal spectrum. Coronal model spectra incorporating the effects of electron temperature and its flow speed were matched with the measured K-coronal spectra to interpret the observations. Results show electron temperatures of (1.10±0.05) MK, (0.70±0.08) MK, and (0.98±0.12) MK, at 1.1 R from Sun center in the solar north, east and west, respectively, and (0.93±0.12) MK, at 1.2 R from Sun center in the solar west. The corresponding outflow speeds obtained from the spectral fit are (103±92) km s−1, (0+10) km s−1, (0+10) km s−1, and (0+10) km s−1. Since the observations were taken only at 1.1 R and 1.2 R from Sun center, these speeds, consistent with zero outflow, are in agreement with expectations and provide additional confirmation that the spectral fitting method is working. The electron temperature at 1.1 R from Sun center is larger at the north (polar region) than the east and west (equatorial region). Title: Statistical Determination and Comparison of Non-thermal Velocity Distributions from EIS Full-CCD Linewidth Measurements Authors: Coyner, Aaron J.; Davila, J. M.; Kilper, G. K. Bibcode: 2011SPD....42.1816C Altcode: 2011BAAS..43S.1816C Excess broadening in the emission line spectra from non-thermal motions provide an unresolved energy input into the coronal plasma. The driving mechanism for and significance of the energy contributions of this non-thermal component has been a subject of much discussion. Observationally constraining the non-thermal contributions to line broadening in the coronal emission spectra provides valuable limitations which coronal physics models must take into account. Using full-CCD raster observations from EIS, we determine a distribution of non-thermal velocities for all lines in each full-CCD raster observation for both spatially-averaged and spatially-resolved EIS spectra. We present here composite non-thermal velocity distributions incorporating a multiple elements, ionization states and temperatures for a variety of EIS observations including both active region and quiet sun emission. We determine an expectation value for the velocity of the non-thermal component from this composite statistical approach. Initial spatially-averaged results from 7 independent EIS rasters show a strong Gaussian peak at approximately 20 km/s per second.. We address the implications of this consistent velocity and energy peak in the spatially-averaged results as well as present and compare our analysis from spatially-resolved spectra for each EIS raster included in the spatially-averaged study. Title: Evidence For Forced Kink-mode Loop Oscillations Observed By Sdo/aia Authors: Wang, Tongjiang; Ofman, L.; Davila, J. M.; Su, Y. Bibcode: 2011SPD....42.2113W Altcode: 2011BAAS..43S.2113W Transverse loop oscillations were first discovered by TRACE in EUV wavelength and interpreted as global fast kink modes. These oscillations are impulsively excited by flares or filament eruptions and often show a strong damping within few oscillation periods. The oscillations and the damping mechanism have been intensively studied in observation and theory, leading to great advance in coronal seismology. However, measurements of the damping rate remains difficult, often limited by the short length of the detectable oscillation sequence in one single filter. SDO/AIA with multiple wavebands of unprecedentedly high sensitivity and wide temperature coverage provides a good opportunity in improving the accuracy of these measurements. Here we present an example of long-lasting oscillation events observed using SDO/AIA. In this event, kink oscillations of a slowly evolving coronal loop seen in 171, 193 and 211 A bands are excited by several flow ejections. The oscillations last over one and a half hours with periods of 3-4 min and no evident decay. In particular, the amplitudes of the oscillations show increase during the period of a large flow ejection with speeds of 200-300 km/s which lasts for about a half hour, and then falls down at speeds of 60-70 km/s measured in 304 A band. We interpret the growing oscillations as driven fast magnetosonic waves by impacting flows. We perform preliminary 3D MHD study of the event using an idealized bipolar active region model. Title: 3D Structure and the Evolution of EUV Bright Points Observed by STEREO/SECCHI/EUVI: Evidence for Coronal Magnetic Reconnection Driven by Emerging Magnetic Flux? Authors: Kwon, Ryun Young; Davila, J. M.; Ofman, L. Bibcode: 2011SPD....42.1808K Altcode: 2011BAAS..43S.1808K The 3D structure of EUV bright points and its physical relation with the underlying magnetic flux concentrations are unveiled here observationally for the first time. The heights of EUV bright points have been measured within their lifetimes by 3D reconstruction method developed by Kwon, Chae, & Zhang (2010) using data sets taken from STEREO/SECCHI/EUVI. We found three distinct changes in the heights which were decreasing, increasing, and constant. In general, EUV bright points are multi-temperature loop system whose hot loops (T 106.2K) with an average height of 8.9Mm are overlying cooler loops (T < 106.0K) with an average height of 6.7Mm. This loop system has cool legs which have the peak temperature of T 104.9K and an average height of 5.2Mm. The heights were found to have remarkable correlations with lengths and distances of two opposite magnetic flux concentrations, indicating that the 3D structures of bright points were determined by the geometry of associated photospheric magnetic fluxes. Accordingly, the three types of bright points we found were associated with three distinct types of their underlying magnetic fragments: converging, diverging, and shearing. In all cases, both flux emergences and flux cancellations were observed during the lifetimes of the bright points. The flux emergences were dominant in the initial phase and the flux cancellations were significant after the intensities reached their maxima. Our results suggest that EUV bright points may be the flaring loop systems (Masuda et al. 1994) formed by coroanl magnetic reconnection and the flux emergence appears to be important to driving the coronal magnetic reconnection. Title: Deconvolution of Spatial and Spectral Information in Slitless Spectrometer Images Authors: Jones, Shaela I.; Davila, J. M. Bibcode: 2011SPD....42.1508J Altcode: 2011BAAS..43S.1508J Observation of coronal emission has greatly enhanced our understanding of the solar corona. However, to date solar scientists have been forced to choose between the large fields of view offered by imaging telescopes and the detailed spectral information offered by imaging spectrometers. In order to measure spectral characteristics over large portions of the corona, imaging spectrometers must raster over the area, a time-consuming process that lowers the effective time cadence of the resulting observations and causes confusion between spatial and temporal variation. Slitless spectrometers, which produce images with convolved spatial and spectral information from a relatively large field of view, offer the opportunity to study the emission line profiles of large regions of the corona without rastering, if the spatial and spectral information can be reliably deconvolved. Here we present a study of the potential capabilities of such an instrument, including examples showing deconvolution of artificial slitless spectrometer images based on Hinode EIS spectral measurements. We compare the expected accuracy of intensities, linewidths, and doppler shifts measured using our deconvolution technique to those derived from fitting of EIS spectral data. Title: Solar Eruptive Events (SEE) Mission for the Next Solar Maximum Authors: Lin, Robert P.; Krucker, S.; Caspi, A.; Hurford, G.; Dennis, B.; Holman, G.; Christe, S.; Shih, A. Y.; Bandler, S.; Davila, J.; Milligan, R.; Kahler, S.; Weidenbeck, M.; Doschek, G.; Vourlidas, A.; Share, G.; Raymond, J.; McConnell, M.; Emslie, G. Bibcode: 2011SPD....42.2204L Altcode: 2011BAAS..43S.2204L Major solar eruptive events consisting of both a large flare and a near simultaneous large fast coronal mass ejection (CME), are the most powerful explosions and also the most powerful and energetic particle accelerators in the solar system, producing solar energetic particles (SEPs) up to tens of GeV for ions and 10s-100s of MeV for electrons. The intense fluxes of escaping SEPs are a major hazard for humans in space and for spacecraft. Furthermore, the solar plasma ejected at high speed in the fast CME completely restructures the interplanetary medium, producing the most extreme space weather in geospace, at other planets, and in the heliosphere. Thus, the understanding of the flare/CME energy release process and of the related particle acceleration processes in SEEs is a major goal in Heliophysics. Here we present a concept for a Solar Eruptive Events (SEE) mission, consisting of a comprehensive set of advanced new instruments on the single spacecraft in low Earth orbit, that focus directly on the coronal energy release and particle acceleration in flares and CMEs. SEE will provide new focussing hard X-ray imaging spectroscopy of energetic electrons in the flare acceleration region, new energetic neutral atom (ENA) imaging spectroscopy of SEPs being accelerated by the CME at altitudes above 2 solar radii, gamma-ray imaging spectroscopy of flare-accelerated energetic ions, plus detailed EUV/UV/Soft X-ray diagnostics of the plasmas density, temperature, and mass motions in the energy release and particle acceleration regions. Together with ground-based measurements of coronal magnetic fields from ATST, FASR, and COSMO, SEE will enable major breakthroughs in our understanding of the fundamental physical processes involved in major solar eruptive events. 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: Slitless Solar Spectroscopy Authors: Davila, Joseph M. Bibcode: 2011SPD....42.1520D Altcode: 2011BAAS..43S.1520D Spectrographs have traditionally suffered from the inability to obtain line intensities, widths, and Doppler shifts over large spatial regions of the Sun quickly because of the narrow instantaneous field of view. This has limited the spectroscopic analysis of rapidly varying solar features like, flares, CME eruptions, coronal jets, and reconnection regions. Imagers have provided high time resolution images of the full Sun with limited spectral resolution.

In this paper we present recent advances in deconvolving spectrally dispersed images obtained through broad slits. We use this new theoretical formulation to examine the effectiveness of various potential observing scenarios, spatial and spectral resolutions, signal to noise ratio, and other instrument characteristics.

This information will lay the foundation for a new generation of spectral imagers optimized for slitless spectral operation, while retaining the ability to obtain spectral information in transient solar events. Title: Modeling Waves And Flows In Active Region Loops Authors: Ofman, Leon; Wang, T.; Davila, J. M. Bibcode: 2011SPD....42.1815O Altcode: 2011BAAS..43S.1815O Recent Hinode/EIS observations indicated that slow magnetosonic waves are present in active region loops. Some of the spectral data were also interpreted as evidence of quasi-periodic flows. We perform three dimensional MHD model of an active region with waves and flows in coronal loops. The model is initiated with a dipole magnetic field and gravitationally stratified density, and velocity pulses are driven periodically in localized regions at the footpoints of magnetic loops. The resulting flows produce higher density loops compared to the surrounding plasma by injecting material along the field. We find that the excitation of periodic flows with subsonic speeds result in the excitation of slow magnetosonic waves that propagate along the loops. The phase speed of the waves is 100 km/s, close to coronal sound speed. When the amplitude of the driving pulses is increased we find that slow shock trains are produced. Using the results of the 3D MHD model we suggest that the observed slow magnetosonic waves and quasi periodic-flows are driven by the same quasi-periodic impulsive events at the bases of active regions. Title: New Capabilities of the EUNIS Sounding Rocket Instrument Authors: Daw, Adrian N.; Brosius, J.; Criscuolo, E.; Davila, J.; Haas, J. P.; Hilton, G.; Linard, D.; Plummer, T.; Rabin, D.; Thomas, R.; Varney, D.; Wang, T. Bibcode: 2011SPD....42.1502D Altcode: 2011BAAS..43S.1502D The upcoming flight of the Extreme Ultraviolet Normal Incidence Spectrograph (EUNIS) sounding rocket instrument, a two-channel imaging spectrograph that observes the solar corona and transition region with high spectral resolution and a rapid cadence made possible by unprecedented sensitivity, will incorporate a new wavelength channel and cooling of the active pixel sensor (APS) arrays. The new 52.4-63.0 nm channel incorporates a Toroidal Varied Line Space (TVLS) grating coated with B4C/Ir, providing broad spectral coverage and a wide temperature range of 0.025 to 10 MK. The APS arrays for both the 52-63 nm and 30-37 nm channels will be cooled to -20 C to reduce dark current noise. With the resulting read-noise limited performance, over a dozen new diagnostic line pairs become available in the two wavelength channels. To our knowledge, this will be the first flight demonstration of cooled APS arrays. EUNIS will co-observe dynamic coronal phenomena with SDO/AIA and Hinode/EIS and will contribute to the absolute radiometric calibrations of these instruments.

EUNIS is supported by NASA through the Low Cost Access to Space Program in Solar and Heliospheric Physics. Title: Slow-Mode Oscillations of Hot Coronal Loops Excited at Flaring Footpoints Authors: Wang, Tongjiang; Liu, W.; Ofman, L.; Davila, J. M. Bibcode: 2011SPD....42.2214W Altcode: 2011BAAS..43S.2214W A large number of strongly damped oscillations in hot coronal loops have been observed by SOHO/SUMER in the past decade in Doppler shifts of flaring (>6 MK) lines (Fe XIX and Fe XXI). These oscillations with periods on the order of 10-30 min were interpreted as fundamental standing slow modes. They often manifest features such as recurrence and association with a flow (100-300 km/s) pulse preceding to the oscillation, which suggests that they are likely driven by microflares at the footpoints. With coordinated RHESSI observations, we have found a dozen such events supporting this conjecture. A typical event is presetned here. By analyzing RHESSI hard X-ray and GOES/SXI soft X-ray emissions as well as SUMER Doppler shifts, we identify the flare that triggers the loop oscillations. From RHESSI spectra, we measure physical parameters such as temperature, emission measure, and thermal/non-thermal energy contents as functions of time. We discuss the wave excitation mechanism based on these observations. Our results provide important observational constraints that can be used for improving theoretical models of magnetosonic wave excitation, and for coronal seismology. Title: Earth-Affecting Solar Causes Observatory (EASCO): A potential International Living with a Star Mission from Sun-Earth L5 Authors: Gopalswamy, N.; Davila, J. M.; St. Cyr, O. C.; Sittler, E. C.; Auchère, F.; Duvall, T. L.; Hoeksema, J. T.; Maksimovic, M.; MacDowall, R. J.; Szabo, A.; Collier, M. R. Bibcode: 2011JASTP..73..658G Altcode: This paper describes the scientific rationale for an L5 mission and a partial list of key scientific instruments the mission should carry. The L5 vantage point provides an unprecedented view of the solar disturbances and their solar sources that can greatly advance the science behind space weather. A coronagraph and a heliospheric imager at L5 will be able to view CMEs broadsided, so space speed of the Earth-directed CMEs can be measured accurately and their radial structure discerned. In addition, an inner coronal imager and a magnetograph from L5 can give advance information on active regions and coronal holes that will soon rotate on to the solar disk. Radio remote sensing at low frequencies can provide information on shock-driving CMEs, the most dangerous of all CMEs. Coordinated helioseismic measurements from the Sun-Earth line and L5 provide information on the physical conditions at the base of the convection zone, where solar magnetism originates. Finally, in situ measurements at L5 can provide information on the large-scale solar wind structures (corotating interaction regions (CIRs)) heading towards Earth that potentially result in adverse space weather. Title: The International Space Weather Initiative (ISWI) Authors: Davila, Joseph M.; Gopalswamy, Nat; Thompson, Barbara J.; Bogdan, Tom; Hapgood, Mike Bibcode: 2011sswh.book..375D Altcode: No abstract at ADS Title: Tracking the Topology of the Photospheric Magnetic Network in Multiscale Space-time: Towards New Precursors of Transient Coronal Events Authors: Coyner, A. J.; Uritsky, V. M.; Davila, J. M. Bibcode: 2010AGUFMSH43B1823C Altcode: We present a new approach to exploring magnetic flux dynamics in the solar photosphere as depicted by high-resolution spacecraft observations, and provide statistical evidence for the correlated cancellation behavior of bipolar magnetic structures over a range of scales associated with meso- and supergranulation suggesting the involvement of these unstable structures in the coronal heating and flaring activity. Our methodology is based on spatio-temporal tracking of magnetic elements allowing us to rigorously identify timing and positions of magnetic emergence and submergence events. The causal relationship between these events is investigated further using the cross-correlation integral algorithm (Uritsky et al., 2010). We apply this two-step approach to an extensive set of SOHO MDI and Hinode SOT V/I magnetograms exhibiting various types of unipolar and bipolar magnetic structures observed in active and quiet regions of the solar photosphere. The results show a significant difference in the behavior of unipolar and bipolar magnetic elements, confirming previously found asymmetry in the emergence and cancellation dynamics of the photospheric magnetic flux. Our analysis also reveals characteristic spatial scales of mesogranular structures of the same and opposing magnetic polarity. Finally, we identify a distinct subset of positively correlated submergence events detected under active photospheric conditions. We argue that these events may represent the reconnection dynamics of the closed magnetic flux, and therefore be responsible for the local coronal dissipation. This possibility is tested using conjugate sets of STEREO EUVI and SOHO MDI images. Title: International Space Weather Initiative (ISWI) Authors: Gopalswamy, N.; Davila, J. M. Bibcode: 2010nspm.conf..160G Altcode: The International Space Weather Initiative (ISWI) is an international scientific program to understand the external drivers of space weather. The science and applications of space weather has been brought to prominence because of the rapid development of space based technology that is useful for all human beings. The ISWI program has its roots in the successful International Heliophysical Year (IHY) program that ran during 2007 - 2009. The primary objective of the ISWI program is to advance the science space weather by a combination of instrument deployment, analysis and interpretation of space weather data from the instruments deployed in conjunction with space data, and communicate the results to the public and students. Like the IHY, the ISWI will be a grass roots organization with key participation from national coordinators with cooperation in an international steering committee. This talk outlines the ISWI program including its organization and proposed activities. Title: Opportunities for Ionospheric Science as Part of the International Space Weather Initiative (ISWI) (Invited) Authors: Davila, J. M.; Gopalswamy, N.; Haubold, H. Bibcode: 2010AGUFMSA43C..01D Altcode: The International Heliophysical Year (IHY), which lasted for approximately two years and involved the effort of thousands of scientists from over 70 countries, ended in February 2009. The major objectives of the IHY included over 60 collaborative studies of universal physical processes in the solar system, the deployment of arrays of small instruments to observe heliophysical processes, a unique program of educational and public outreach, and the preservation of the history of the IGY. The International Space Weather Initiative (ISWI), an international effort fully supported by the United Nations, is designed to build on the momentum developed during the IHY to develop the capability to observe, understand, and predict space weather phenomena, and provide the opportunity for the deployment of new instrumentation in Africa and other regions. In this talk the basic elements of the ISWI will be discussed, and the opportunities for the deployment of new instrument will be discussed. Title: Connecting CME expansion from Sun to 1 AU Authors: Nieves-Chinchilla, T.; Colaninno, R. C.; Vourlidas, A.; Szabo, A.; Vinas, A. F.; Davila, J. M. Bibcode: 2010AGUFMSH23B1841N Altcode: EUV disk imagers and white light coronagraphs have provided for many years information on the early formation and evolution of coronal mass ejections (CMEs). More recently, the novel heliospheric imaging instruments aboard the STEREO mission are providing crucial remote sensing information on the interplanetary evolution of these events while in situ instruments complete the overall characterization of the interplanetary CMEs. In this work, we present an analysis of CMEs from the Sun to the interplanetary medium using combined data from SDO, SOHO, STEREO, WIND, and ACE spacecraft. From the remote sensing analysis, the most notable feature of a CME observed in the SECCHI suite of instruments field of view is its elliptic cross section. However, most of the models for in situ modeling impose the circular cross-section geometry. In this work, we link the remote sensing observations with the in situ data through an analytical in situ model which incorporates the distortion in the cross-section. In this study, different aspects such as the ambient solar wind, magnetic field configurations, plasma parameters, etc, have been taken into account in order to cover the widest spectrum of possible scenarios. Title: The Future of IHY Campaigns: Transition to the International Space Weather Initiative Authors: Raulin, Jean-Pierre; Davila, Joseph M.; Bogdan, Thomas; Yumoto, Kiyohumi; Leibacher, John Bibcode: 2010HiA....15..501R Altcode: We will present the relevant activities performed during the International Heliophysical Year (IHY) program during the 5 year period 2004 - 2008. The IHY was a major international effort that involved the deployment of new instrumentation, new observations from the ground and in space, and a strong education component. Under the United Nations Office for Outer Space program called Basic Space Science Initiative (UNBSSI), instrument arrays have been deployed to provide global measurements of heliophysical phenomena. As a result, significant scientific and educational collaborations emerged between the organizing groups and the host country teams. In view of the great successes achieved by the IHY during these years, we propose to continue the highly successful collaboration with the UN program to study the universal processes in the solar system that affect the interplanetary and terrestrial environments, and to continue to coordinate the deployment and operation of new and existing instrumentation arrays aimed at understanding the impacts of Space Weather on Earth and the near-Earth environment. To this end, we propose a new program, the International Space Weather Initiative (ISWI). The ISWI strongly complements the International Living With a Star (ILWS) program, providing more attention nationally, regionally, and internationally for the ILWS program. Based on a three-year program activity, the ISWI would provide the opportunity for scientists around the world to participate in this exciting quest to understand the effect of space disturbances on our Earth environment. Title: Multi-day Precursors to Prominence Eruptions Authors: Kilper, Gary; Davila, Joseph Bibcode: 2010shin.confE.103K Altcode: Prominence eruptions are highly correlated to CMEs, and a better understanding of them would enhance the ability to forecast hazardous space weather. Increases in absorption, strong flows, cavity expansion, low-level heating, and photospheric flux cancellation have all been found prior to eruptions. Our recent research has analyzed most of these properties simultaneously and found that they are related, and they collectively start a day or more prior to eruption onset. These findings can be used to predict extended windows in which a prominence eruption is unlikely to occur. Title: Towards a New Formation Flying Solar Coronagraph Authors: Lamy, P.; Vives, S.; Curdt, W.; Dame, L.; Davila, J.; Defise, J. M.; Fineschi, S.; Heinzel, P.; Kuzin, S.; Schmutz, W.; Tsinganos, K.; Turck-Chieze, S.; Zhukov, A. Bibcode: 2010ASPC..424...15L Altcode: We briefly describe an investigation aiming at the development of a giant solar coronagraph instrument onboard of two satellites, separated by about 150 m in formation flight for the detailed observation of the solar coronal plasma. The European Space Agency (ESA) has selected this instrument as the only payload onboard the Proba 3 satellites which will be launched in 2013. The Greek team is developing the command control board of the coronagraph. Title: A Complete Observational Picture of Quiet Sun Prominence Eruptions Authors: Kilper, Gary; Davila, J. Bibcode: 2010AAS...21640302K Altcode: 2010BAAS...41..878K A relation between prominence eruptions and coronal mass ejections is well established, and several possible eruption models have been formulated. However, the observational side had lacked the necessary statistical studies to permit any decisive conclusions. Recently, large databases of observations have allowed detailed and thorough analyses of the prominence plasma, surrounding cavity, and the magnetic field below. This presentation will highlight these recent results, and describe findings from our new study, which combines simultaneous observations from MLSO, SOHO-MDI and EIT, STEREO-EUVI, and Hinode-XRT. This research was supported by an appointment to the NASA Postdoctoral Program at Goddard Space Flight Center, which is administered by Oak Ridge Associated Universities through a contract with NASA. Title: Absolute Radiometric Calibration Of EUNIS, And Calibration Updates For Hinode/EIS And SOHO/CDS Authors: Wang, Tongjiang; Thomas, R. J.; Brosius, J. W.; Young, P. R.; Rabin, D. M.; Davila, J. M. Bibcode: 2010AAS...21640704W Altcode: 2010BAAS...41..860W The Extreme-Ultraviolet Normal-Incidence Spectrograph sounding rocket payload was flown in 2006 (EUNIS-06) and 2007 (EUNIS-07), each time carrying two independent imaging spectrographs covering wave bands of 300-370 Angstrom in first order and 170-205 Angstrom in second order. For each flight, the absolute radiometric response of the EUNIS long-wavelength (LW) channel was directly measured in the same facility used for pre-flight calibrations of SOHO/CDS and Hinode/EIS. The wavelength range of the EUNIS LW channel overlaps that of CDS/NIS-1, and so can provide a direct calibration update for it. The EUNIS-06 observation shows that the efficiency of CDS/NIS-1 has decreased by a factor about 1.7 compared to that of the previously implemented calibration. Here we present an update to the absolute calibration for Hinode/EIS derived with a technique that combines a direct comparison of line intensities observed in cospatial EUNIS-07 and EIS spectra, along with density- and temperature-insensitive line intensity ratios. Title: On the Vector Tomographic Reconstruction for the pre-CME Coronal Magnetic Field from Fe XIII 10747 A Emission Line Observations Authors: Kramar, Maxim; Lin, H.; Inhester, B.; Davila, J. Bibcode: 2010AAS...21630203K Altcode: Magnetic fields are the dominant fields that determine the static and dynamic properties of the solar corona. The coronal mass ejections (CMEs) involve the release of the magnetic energy stored in the magnetic field. Therefore, analyzing the magnetic field could help to understand the nature of CMEs. One of the more promising coronal magnetic field measurement methods that have been successfully demonstrated is the spectropolarimetric observations of the Fe XIII 10747 A forbidden emission line (Lin, Penn & Tomczyk 2000; Lin, Kuhn & Coulter 2004; Tomczyk et al. 2007) formed due to Hanle and Zeeman effects. However, these measurements are integrated over line-of-sight (LOS). Therefore it is impossible to determine the configuration of the coronal magnetic field from a single observation (single viewing direction).

Vector tomography based on polarimetric observations of the forbidden coronal emission lines can reconstruct the coronal magnetic field when the observations are obtained from several viewing directions. As the tomography method requires observations from many directions, a rigid rotation of the coronal structures during a half of solar rotation is assumed. However, many pre-CME magnetic configurations evolve more rapidly causing significant reduce in the number of available observing directions. Here we study the sensitivity of the vector tomographic inversion to possible pre-CME coronal magnetic field configurations and the number of available observing directions. We show that the vector tomography techniques has the potential to resolve the 3D coronal non-potential magnetic field structure. Title: The 3D Coronal Electron Density Based on STEREO/COR1 Observations for the Year of 2008 Authors: Kramar, Maxim; Davila, J.; Xie, H.; Lamb, D.; Inhester, B. Bibcode: 2010AAS...21640501K Altcode: 2010BAAS...41..889K We present a three dimensional reconstructions of the electron density in the corona at the distances from 1.5 to 4 R for the whole year of 2008, i.e. during solar minimum. The reconstructions is based on STEREO/COR1 data and performed using a regularized tomography inversion method.

The reconstructed streamer belt structure is generally consistent with the neutral magnetic line derived from a potential field extrapolation method (PFSS) for the most of the time. However for some pre-CME events this consistency is less clear. This inconsistency could indicates the non-potentiality of the pre-CME magnetic field configuration. Also it is seen a significant density decrease in the streamer belt after some CME events. This clearly indicates the streamer blow out effect. As we have 3D reconstructed density, the streamer belt mass lost due to that CMEs is estimated. Title: The June 1st 2008 CME in the Interplanetary Medium Authors: Nieves-Chinchilla, T.; F. -Vinas, A.; Gomez-Herrero, R.; Malandraki, O. E.; Dresing, N.; Hidalgo, M. A.; Davila, J. Bibcode: 2010EGUGA..1215133N Altcode: In this work we present a combined study/analysis of the counterpart of the CME of June 1st of 2008 in the interplanetary medium. This event has been largely studied because of its peculiar initiation and its possible forecasting consequences for space weather. We show an in situ analysis of the CME in the interplanetary medium in order to shed some light on the propagation and evolution mechanisms of the ICME. The energetic particles play an important role in order to understand the overall event, the source on the Sun and the effect over the Earth. The typical shock associated characteristics with the counterpart of the CMEs in the interplanetary medium has been determined, in order to understand the propagation properties. The magnetic cloud has been studied and analyzed using non force-free models as start point to incorporate expansion. To accomplish this analysis the IMPACT/STEREO B in-situ measurement have been considered in order to characterize the Interplanetary CME. Title: Propagating Intensity Disturbances In Coronal Loops: Waves Or Flows? Authors: Wang, Tongjiang; Ofman, L.; Davila, J. M. Bibcode: 2010AAS...21640715W Altcode: 2010BAAS...41..862W Quasi-periodic propagating intensity disturbances were found by SOHO/EIT and TRACE imaging observations in fanlike coronal loops 10 year ago. The 3 min and 5 min oscillations have been interpreted as propagating slow magnetoacoustic waves which originate from the photospheric p-mode oscillations due to the wave leakage. However, some cases show oscillations with periodicities of more than 10 min, which are hard to explain by wave leakage, and so were argued in some studies that they may be periodic flows. In this presentation, we report the first observation of multiple-periodic (12 and 25 min) propagating disturbances along a fan-like coronal structure simultaneously detected in both intensity and Doppler shift in the Fe XII line with EIS onboard Hinode. We measured Doppler shift amplitude of 1-2 km/s, relative intensity amplitude of (3-5)% and the apparent propagation speed of 100-120 km/s. The amplitude relationship between intensity and Doppler shift oscillations provides convincing evidence that these propagating features are a manifestation of slow magnetoacoustic waves but not flows. The feature of symmetric line profiles also confirms that the measured small Doppler-shift amplitudes are not due to the line wing enhancement caused by high-speed flows. A new application of coronal seismology is provided based on these observations, with which we determine the inclination angle of the magnetic field and the temperature of a coronal loop. We will also show the result of multi-temperature line analysis to explore the temperature-dependent behavior of this phenomenon. Title: Determination Of Non-thermal Velocity Distributions From Spatially-averaged EUV Spectra Observed With SERTS And Hinode/EIS Authors: Coyner, Aaron J.; Davila, J. M. Bibcode: 2010AAS...21640710C Altcode: 2010BAAS...41..861C Unresolved non-thermal broadenings have been reported in observations of solar EUV spectra for decades. These unresolved broadenings are generally attributed to non-thermal motions within coronal plasma loops and have been shown to provide a limitation on the maximum available energy in the coronal plasma to facilitate coronal heating. Therefore, determining an average non-thermal velocity component of the broadening in observed EUV line profiles provides a significant observational constraint for all coronal heating models to address. We have analyzed spatially-averaged spectra from both the Solar EUV Research Telescope and Spectrograph (SERTS) over the EUV bandpass from 170-420 angstroms in a variety of solar conditions, from quiet sun to active region to off-limb data. For each instrument, we construct a non-thermal velocity, <Vnth2>, distributions for active region and quiet sun emission lines respectively. We then fit each distribution with a Gaussian to determine the typical unresolved non-thermal velocities observed in both quiet sun and active region distributions. Ideally, if no non-thermal component exists the distributions would all peak at zero, but in the case of the SERTS observations, we find the distributions peak at velocities between 21-25 km/s regardless of solar activity. Building off of the SERTS analysis, we create similar distributions using spatially-averaged line profiles from Hinode/EIS observations to use the increased spectral resolution of EIS to refine the non-thermal velocity constraints determined with SERTS. Title: Emission lines of FeXI in the 257-407Å wavelength region observed in solar spectra from EIS/Hinode and SERTS Authors: Keenan, F. P.; Milligan, R. O.; Jess, D. B.; Aggarwal, K. M.; Mathioudakis, M.; Thomas, R. J.; Brosius, J. W.; Davila, J. M. Bibcode: 2010MNRAS.404.1617K Altcode: 2010MNRAS.tmp..299K; 2010arXiv1001.3627K Theoretical emission-line ratios involving FeXI transitions in the 257-407Å wavelength range are derived using fully relativistic calculations of radiative rates and electron impact excitation cross-sections. These are subsequently compared with both long wavelength channel Extreme-Ultraviolet Imaging Spectrometer (EIS) spectra from the Hinode satellite (covering 245-291Å) and first-order observations (~235-449Å) obtained by the Solar Extreme-ultraviolet Research Telescope and Spectrograph (SERTS). The 266.39, 266.60 and 276.36Å lines of FeXI are detected in two EIS spectra, confirming earlier identifications of these features, and 276.36Å is found to provide an electron density (Ne) diagnostic when ratioed against the 257.55Å transition. Agreement between theory and observation is found to be generally good for the SERTS data sets, with discrepancies normally being due to known line blends, while the 257.55Å feature is detected for the first time in SERTS spectra. The most useful FeXI electron density diagnostic is found to be the 308.54/352.67 intensity ratio, which varies by a factor of 8.4 between Ne = 108 and 1011cm-3, while showing little temperature sensitivity. However, the 349.04/352.67 ratio potentially provides a superior diagnostic, as it involves lines which are closer in wavelength, and varies by a factor of 14.7 between Ne = 108 and 1011cm-3. Unfortunately, the 349.04Å line is relatively weak, and also blended with the second-order FeX 174.52Å feature, unless the first-order instrument response is enhanced. Title: Three-Dimensional Polarimetric Coronal Mass Ejection Localization Tested Through Triangulation Authors: Moran, Thomas G.; Davila, Joseph M.; Thompson, William T. Bibcode: 2010ApJ...712..453M Altcode: We have tested the validity of the coronal mass ejection (CME) polarimetric reconstruction technique for the first time using triangulation and demonstrated that it can provide the angle and distance of CMEs to the plane of the sky. In this study, we determined the three-dimensional orientation of the CMEs that occurred on 2007 August 21 and 2007 December 31 using polarimetric observations obtained simultaneously with the Solar Terrestrial Relations Observatory/Sun Earth Connection Coronal and Heliospheric Investigation spacecraft COR1-A and COR1-B coronagraphs. We obtained the CME orientations using both the triangulation and polarimetric techniques and found that angles to the sky plane yielded by the two methods agree to within ≈ 5°, validating the polarimetric reconstruction technique used to analyze CMEs observed with the Solar and Heliospheric Observatory/Large Angle Spectrometric Coronagraph. In addition, we located the CME source regions using EUV and magnetic field measurements and found that the corresponding mean angles to the sky plane of those regions agreed with those yielded by the geometric and polarimetric methods within uncertainties. Furthermore, we compared the locations provided by polarimetric COR1 analysis with those determined from other analyses using COR2 observations combined with geometric techniques and forward modeling. We found good agreement with those studies relying on geometric techniques but obtained results contradictory to those provided by forward modeling. Title: Background Subtraction for the SECCHI/COR1 Telescope Aboard STEREO Authors: Thompson, W. T.; Wei, K.; Burkepile, J. T.; Davila, J. M.; St. Cyr, O. C. Bibcode: 2010SoPh..262..213T Altcode: 2010SoPh..tmp...26T COR1 is an internally occulted Lyot coronagraph, part of the Sun Earth Connection Coronal and Heliospheric Investigation (SECCHI) instrument suite aboard the twin Solar Terrestrial Relations Observatory (STEREO) spacecraft. Because the front objective lens is subjected to a full solar flux, the images are dominated by instrumental scattered light which has to be removed to uncover the underlying K corona data. We describe a procedure for removing the instrumental background from COR1 images. F coronal emission is subtracted at the same time. The resulting images are compared with simultaneous data from the Mauna Loa Solar Observatory Mk4 coronagraph. We find that the background subtraction technique is successful in coronal streamers, while the baseline emission in coronal holes (i.e. between plumes) is suppressed. This is an expected behavior of the background subtraction technique. The COR1 radiometric calibration is found to be either 10 - 15% lower, or 5 - 10% higher than that of the Mk4, depending on what value is used for the Mk4 plate scale, while an earlier study found the COR1 radiometric response to be ∼ 20% higher than that of the Large Angle Spectroscopic Coronagraph (LASCO) C2 telescope. Thus, the COR1 calibration is solidly within the range of other operating coronagraphs. The background levels in both COR1 telescopes have been quite steady in time, with the exception of a single contamination event on 30 January 2009. Barring too many additional events of this kind, there is every reason to believe that both COR1 telescopes will maintain usable levels of scattered light for the remainder of the STEREO mission. Title: Absolute Radiometric Calibration of the EUNIS-06 170-205 Å Channel and Calibration Update for Coronal Diagnostic Spectrometer/Normal-Incidence Spectrometer Authors: Wang, Tongjiang; Brosius, Jeffrey W.; Thomas, Roger J.; Rabin, Douglas M.; Davila, Joseph M. Bibcode: 2010ApJS..186..222W Altcode: 2009arXiv0912.2328W The Extreme-Ultraviolet Normal-Incidence Spectrograph sounding-rocket payload was flown on 2006 April 12 (EUNIS-06), carrying two independent imaging spectrographs covering wavebands of 300-370 Å in first order and 170-205 Å in second order, respectively. The absolute radiometric response of the EUNIS-06 long-wavelength (LW) channel was directly measured in the same facility used to calibrate Coronal Diagnostic Spectrometer (CDS) prior to the Solar and Heliospheric Observatory (SOHO) launch. Because the absolute calibration of the short-wavelength (SW) channel could not be obtained from the same lab configuration, we here present a technique to derive it using a combination of solar LW spectra and density- and temperature-insensitive line intensity ratios. The first step in this procedure is to use the coordinated, cospatial EUNIS and SOHO/CDS spectra to carry out an intensity calibration update for the CDS NIS-1 waveband, which shows that its efficiency has decreased by a factor about 1.7 compared to that of the previously implemented calibration. Then, theoretical insensitive line ratios obtained from CHIANTI allow us to determine absolute intensities of emission lines within the EUNIS SW bandpass from those of cospatial CDS/NIS-1 spectra after the EUNIS LW calibration correction. A total of 12 ratios derived from intensities of 5 CDS and 12 SW emission lines from Fe X to Fe XIII yield an instrumental response curve for the EUNIS-06 SW channel that matches well to a relative calibration which relied on combining measurements of individual optical components. Taking into account all potential sources of error, we estimate that the EUNIS-06 SW absolute calibration is accurate to ±20%. Title: Propagating intensity disturbances in coronal loops: Waves or flows? Authors: Wang, Tongjiang; Ofman, Leon; Davila, Joseph Bibcode: 2010cosp...38.2924W Altcode: 2010cosp.meet.2924W Quasi-periodic propagating intensity disturbances were found by SOHO/EIT and TRACE imaging observations in fanlike coronal loops 10 year ago. The 3 min and 5 min oscillations have been interpreted as propagating slow magnetoacoustic waves which originate from the photospheric p-mode oscillations due to the wave leakage. However, some cases show oscil-lations with periodicities of more than 10 min, which are hard to explain by wave leakage, and so were argued in some studies that they may be periodic flows. In this presentation, we report the first observation of multiple-periodic (12 and 25 min) propagating disturbances along a fan-like coronal structure simultaneously detected in both intensity and Doppler shift in the Fe xii line with EIS onboard Hinode. We measured Doppler shift amplitude of 1-2 km/s, relative intensity amplitude of (3-5)% and the apparent propagation speed of 100-120 km/s. The amplitude relationship between intensity and Doppler shift oscillations provides convinc-ing evidence that these propagating features are a manifestation of slow magnetoacoustic waves but not flows. The feature of symmetric line profiles also confirms that the measured small Doppler-shift amplitudes are not due to the line wing enhancement caused by high-speed flows. A new application of coronal seismology is provided based on these observations, with which we determine the inclination angle of the magnetic field and the temperature of a coronal loop. We will also show the result of multi-temperature spectral line analysis to explore the temperature-dependent behavior of this phenomenon. Title: ASPIICS / PROBA-3: a formation flying externally-occulted giant coronagraph mission Authors: Lamy, Philippe; Damé, Luc; Curdt, W.; Davila, J.; Defise, J. M.; Fineschi, S.; Heinzel, P.; Howard, R.; Kuzin, S.; Schmutz, W.; Tsinganos, K.; Turck-Chièze, S.; Zhukov, A. Bibcode: 2010cosp...38.2858L Altcode: 2010cosp.meet.2858L Classical externally-occulted coronagraphs are presently limited in their performances by the distance between the external occulter and the front objective. The diffraction fringe from the occulter and the vignetted pupil which degrades the spatial resolution prevent useful observa-tions of the white light corona inside typically 2-2.5 Rsun. Formation flying offers an elegant solution to these limitations and allows conceiving giant, externally-occulted coronagraphs us-ing a two-component space system with the external occulter on one spacecraft and the optical instrument on the other spacecraft at distances of hundred meters. Such an instrument has just been selected by ESA to fly (by the end of 2013) on its PROBA-3 mission, presently in phase B, to demonstrate formation flying. It will perform both high spatial resolution imaging of the solar corona as well as 2-dimensional spectroscopy of several emission lines (in partic-ular the forbidden line of FeXIV at 530.285 nm) from the coronal base out to 3 Rsun using a Fabry-Perot interferometer. The classical design of an externally-occulted coronagraph is adapted to the formation flying configuration allowing the detection of the very inner corona as close as 0.05 Rsun from the solar limb. By tuning the position of the occulter spacecraft, it may even be possible to try reaching the chromosphere and the upper part of the spicules. ASPIICS/PROBA-3 mission, payload and scientific objectives are detailed. Title: Estimation of coronal magnetic field using the type II radio burst associated with a fast CME Authors: Gopalswamy, Nat; Yashiro, Seiji; Akiyama, Sachiko; Freeland, Samuel; Davila, Joseph; Howard, Russell; Bougeret, J. -L. Bibcode: 2010cosp...38.1808G Altcode: 2010cosp.meet.1808G The 2008 March 25 coronal mass ejection (CME) was the second fastest among the 10 type II producing CMEs in the STEREO era. The CME was accompanied by a EUV wave and a shock discernible in the white-light data. The type II burst was observed in the metric and decameter-hectometer (DH) wavelength domains. The type II burst ended in the DH domain when the CME speed started declining at a heliocentric distance where the Alfven speed reached its peak value. Under the scenario that the type II burst was caused by a CME-driven shock, we see that the end of the type II burst corresponds to a significant weakening of the shock, making it subcritical. The standoff distance between the flux rope structure and the shock significantly increased at the time of the shock weakening. From the observed standoff distance, we estimated the upstream Alfvenic Mach number and hence the coronal magnetic field. The magnetic field derived (0.04 G) is consistent with typical quiet solar atmosphere at 7 solar radii. Title: Multi-spacecraft observation of a magnetic cloud Authors: de Lucas, Aline; Dal Lago, Alisson; Schwenn, Rainer; Clúa de Gonzalez, Alicia L.; Marsch, Eckart; Lamy, Philippe; Damé, Luc; Curdt, W.; Davila, J.; Defise, J. M.; Fineschi, S.; Heinzel, P.; Howard, R.; Kuzin, S.; Schmutz, W.; Tsinganos, K.; Turck-Chièze, S.; Zhukov, A. Bibcode: 2010cosp...38.1921D Altcode: 2010cosp.meet.1921D Classical externally-occulted coronagraphs are presently limited in their performances by the distance between the external occulter and the front objective. The diffraction fringe from the occulter and the vignetted pupil which degrades the spatial resolution prevent useful observa-tions of the white light corona inside typically 2-2.5 Rsun. Formation flying offers an elegant solution to these limitations and allows conceiving giant, externally-occulted coronagraphs us-ing a two-component space system with the external occulter on one spacecraft and the optical instrument on the other spacecraft at distances of hundred meters. Such an instrument has just been selected by ESA to fly (by the end of 2013) on its PROBA-3 mission, presently in phase B, to demonstrate formation flying. It will perform both high spatial resolution imaging of the solar corona as well as 2-dimensional spectroscopy of several emission lines (in partic-ular the forbidden line of FeXIV at 530.285 nm) from the coronal base out to 3 Rsun using a Fabry-Perot interferometer. The classical design of an externally-occulted coronagraph is adapted to the formation flying configuration allowing the detection of the very inner corona as close as 0.05 Rsun from the solar limb. By tuning the position of the occulter spacecraft, it may even be possible to try reaching the chromosphere and the upper part of the spicules. ASPIICS/PROBA-3 mission, payload and scientific objectives are presented. Title: Vector tomographic reconstruction for the coronal magnetic field from Fe XIII 10747 A emission line observations Authors: Kramar, Maxim; Lin, Haosheng; Inhester, Bernd; Davila, Joseph Bibcode: 2010cosp...38.1862K Altcode: 2010cosp.meet.1862K Magnetic fields in the solar corona are the dominant fields that determine the static and dy-namic properties of this outermost region of the solar atmosphere. It is within this tenuous region that the magnetic force dominates the gas pressure. Direct measurement of the coronal magnetic field is one of the most challenging problems in observational solar astronomy. To date, one of the promising measurement methods that have been successfully demonstrated is the spectropolarimetric measurement of the Fe XIII 10747 A forbidden emission line (Lin, Penn Tomczyk 2000; Lin, Kuhn Coulter 2004; Tomczyk et al. 2007) formed due to Hanle and Zeeman effects. However, because coronal measurements are integrated over line-of-site (LOS), it is impossible to derive the configuration of the coronal magnetic field from a single obser-vation (from a single viewing direction). In this paper, we study the sensitivity of the vector tomographic inversion to possible pre-CME coronal magnetic field configurations and number of available observations. We show that the vector tomography techniques based on Hanle and/or Zeeman effect observations has the potential to resolve the 3D coronal non-potential magnetic field structure. Title: The 3D reconstructions of the coronal electron density in the range 1.5-4 Rsun for the whole year of 2008 Authors: Kramar, Maxim; Davila, Joseph; Lamb, Derek; Xie, Hong Bibcode: 2010cosp...38.1920K Altcode: 2010cosp.meet.1920K We present a three dimensional reconstructions of the electron density in the corona at the distances from 1.5 to 4R for the whole year of 2008, i.e. during solar minimum. The recon-structions is based on STEREO/COR1 data and performed using a regularized tomography inversion method. The reconstructed streamer belt structure is generally consistent with the neutral magnetic line derived from a potential field extrapolation method (PFSS) for the most of the time. However for some pre-CME events this consistency is less clear. This inconsistency could indicates the non-potentiality of the pre-CME magnetic field configuration. Also it is seen a significant density decrease in the streamer belt after some CME events. This clearly indicates the streamer blow out effect. As we have 3D reconstructed density, the streamer belt mass lost due to that CMEs is estimated. Title: The International Space Weather Initiative Authors: Davila, Joseph; Gopalswamy, Nat Bibcode: 2010cosp...38.4192D Altcode: 2010cosp.meet.4192D The International Space Weather Initiative (ISWI) is an international program of scientific collaboration to understand the external drivers of space weather. One of the major thrusts of the ISWI is to deploy arrays of small instruments such as magnetometers, radio antennas, GPS receivers, all-sky cameras, particle detectors, etc. around the world to provide global measurements of heliospheric phenomena. Scientists from approximately 70 countries now participate in the instrument operation, data collection, analysis, and publication of scientific results, working at the forefront of science research. The purpose of the ISWI is to continue the scientific study of universal processes in the solar system that affect space weather and the terrestrial environment, and to continue to coordinate the deployment and operation of new and existing instrument arrays aimed at understanding the impacts of Space Weather on Earth and the near-Earth environment. This project provides an excellent opportunity for potential instrument providers to engage collaborators from specific geographical locations, and to broaden the coverage of existing instrument arrays. By deploying instruments in strategically chosen locations new science and a more global view of heliophysical processes is obtained. These data will also provide new inputs for global ionospheric models in the future. Title: On the 3-D reconstruction of Coronal Mass Ejections using coronagraph data Authors: Mierla, M.; Inhester, B.; Antunes, A.; Boursier, Y.; Byrne, J. P.; Colaninno, R.; Davila, J.; de Koning, C. A.; Gallagher, P. T.; Gissot, S.; Howard, R. A.; Howard, T. A.; Kramar, M.; Lamy, P.; Liewer, P. C.; Maloney, S.; Marqué, C.; McAteer, R. T. J.; Moran, T.; Rodriguez, L.; Srivastava, N.; St. Cyr, O. C.; Stenborg, G.; Temmer, M.; Thernisien, A.; Vourlidas, A.; West, M. J.; Wood, B. E.; Zhukov, A. N. Bibcode: 2010AnGeo..28..203M Altcode: Coronal Mass ejections (CMEs) are enormous eruptions of magnetized plasma expelled from the Sun into the interplanetary space, over the course of hours to days. They can create major disturbances in the interplanetary medium and trigger severe magnetic storms when they collide with the Earth's magnetosphere. It is important to know their real speed, propagation direction and 3-D configuration in order to accurately predict their arrival time at the Earth. Using data from the SECCHI coronagraphs onboard the STEREO mission, which was launched in October 2006, we can infer the propagation direction and the 3-D structure of such events. In this review, we first describe different techniques that were used to model the 3-D configuration of CMEs in the coronagraph field of view (up to 15 R⊙). Then, we apply these techniques to different CMEs observed by various coronagraphs. A comparison of results obtained from the application of different reconstruction algorithms is presented and discussed. Title: Hinode/EIS Observations of Propagating Slow Magnetoacoustic Waves in a Coronal Loop Authors: Wang, T. J.; Ofman, L.; Davila, J. M. Bibcode: 2009ASPC..415...28W Altcode: We present the first Hinode/EIS observations of 5 min quasi-periodic oscillations detected in the transition region and corona at the footpoint of a coronal loop. The oscillations are characterized by a series of wave packets with nearly constant period, typically persisting for 4--6 cycles. There is an in-phase relation between Doppler shift and intensity oscillations, indicating upwardly propagating slow magnetoacoustic waves in the loop. We find that the oscillations detected in the five coronal lines are highly correlated, and the amplitude decreases with increasing temperature. These oscillations may be caused by the leakage of the photospheric p-modes through the chromosphere and transition region into the corona, which has been suggested as the source for intensity oscillations previously observed by TRACE. The temperature dependence of the oscillation amplitudes can be explained by damping of the waves traveling along the loop with multithread structure near the footpoint. Title: Recent STEREO Observations of Coronal Mass Ejections Authors: St Cyr, O. C.; Xie, H.; Mays, M. L.; Davila, J. M.; Gilbert, H. R.; Jones, S. I.; Pesnell, W. D.; Gopalswamy, N.; Gurman, J. B.; Yashiro, S.; Wuelser, J.; Howard, R. A.; Thompson, B. J.; Thompson, W. T. Bibcode: 2009AGUFMSH11A1491S Altcode: Over 400 CMEs have been observed by STEREO SECCHI COR1 during the mission's three year duration (2006-2009). Many of the solar activity indicators have been at minimal values over this period, and the Carrington rotation-averaged CME rate has been comparable to that measured during the minima between Cycle 21-22 (SMM C/P) and Cycle 22-23 (SOHO LASCO). That rate is about 0.5 CMEs/day. During the current solar minimum (leading to Cycle 24), there have been entire Carrington rotations where no sunspots were detected and the daily values of the 2800 MHz solar flux remained below 70 sfu. CMEs continued to be detected during these exceptionally quiet periods, indicating that active regions are not necessary to the generation of at least a portion of the CME population. In the past, researchers were limited to a single view of the Sun and could conclude that activity on the unseen portion of the disk might be associated with CMEs. But as the STEREO mission has progressed we have been able to observe an increasing fraction of the Sun's corona with STEREO SECCHI EUVI and were able to eliminate this possibility. Here we report on the nature of CMEs detected during these exceptionally-quiet periods, and we speculate on how the corona remains dynamic during such conditions. Title: Electron-Temperature Maps of the Low Solar Corona: ISCORE Results from the Total Solar Eclipse of 29 March 2006 in Libya Authors: Reginald, Nelson L.; St. Cyr, O. C.; Davila, Joseph M.; Rabin, Douglas M.; Guhathakurta, Madhulika; Hassler, Donald M. Bibcode: 2009SoPh..260..347R Altcode: We conducted an experiment in conjunction with the total solar eclipse of 29 March 2006 in Libya that measured the coronal intensity through two filters centered at 3850 Å and 4100 Å with bandwidths of ≈ 40 Å. The purpose of these measurements was to obtain the intensity ratio through these two filters to determine the electron temperature. The instrument, Imaging Spectrograph of Coronal Electrons (ISCORE), consisted of an eight inch, f/10 Schmidt Cassegrain telescope with a thermoelectrically-cooled CCD camera at the focal plane. Results show electron temperatures of 105 K close to the limb to 3×106 K at 1.3R. We describe this novel technique, and we compare our results to other relevant measurements. This technique could be easily implemented on a space-based platform using a coronagraph to produce global maps of the electron temperature of the solar corona. Title: Coronal Rotation Between 1.5 and 3.5 Solar Radii at Solar Minimum Authors: Jones, S. I.; Davila, J. M. Bibcode: 2009AGUFMSH41B1655J Altcode: Here we report on coronal rotation measurements using STEREO COR1. Multiple studies have confirmed that rotation rates in the outer corona differ markedly from those of the photosphere, where a steady decline in rotation rate with latitude is observed. Emission line observations of low-lying coronal magnetic features typically correspond well with photospheric rotation rates, while white-light measurements in the upper corona indicate very rigid rotation. Some studies have reported a sudden jump in the rotation rate in the 2.3-2.5 R_sun range, indicating a transition from differentially rotating features to rigidly rotating ones. It has been suggested that the rotation rates measured in a given study may be related to the lifetimes of features observed, which should make the simultaneous observation of features rotating at different rates difficult. Using autocorrelation measurements of COR1 data we have studied rotation rates between 1.5 and 3.5 solar radii for features with lifetimes longer than one full rotation. We observe latitudinally and radially rigid rotation during 2007 and 2008, and no transition from differentially rotating to rigidly rotating features. This is consistent with the idea that longer-lived features rotate more rigidly, or with a transition from differential to rigid rotation below 1.5 R_sun. Title: Observational Constraints of Coronal Non-Thermal Velocities from Statistical Analysis of SERTS 1991-1997 Linewidth Observations Authors: Coyner, A. J.; Davila, J. M. Bibcode: 2009AGUFMSH41B1659C Altcode: The determination of non-thermal line broadening and velocities from the spectral linewidth measurements in the EUV provide an observational limits to available energy from unresolved sources within the observed coronal structures. These non-thermal velocity components can result from a number of sources including wave motions , turbulence, and electron beam interactions among others each of which has been suggested as a possible means of generating the required energy for the coronal heating process. .This study presents the determination and statistical analysis of the non-thermal velocity components of 397 identified EUV spectral lines from the combined observations of the SERTS 1991-1997 flights covering the wavelength range from 174-418Å. Similar analysis is also presented for the distributions of active region, quiet sun, and off-limb emission lines respectively which combine to form the composite distribution. We find, for all four of these velocity distributions, a strong non-thermal velocity peak corresponding to a velocity of 20-24 km/s regardless of location or activity level. These velocities suggest the majority of SERTS observed lines do not produce sufficient energy within their non-thermal components to contribute significantly to the heating process and are likely instead to observed motions of plasma cooling into the SERTS temperature range, peaked near 1.4 MK. The active region velocity distribution, however, exhibits evidence of a multi-component distribution through the existence of a high velocity shoulder which can be fit with a secondary distribution peaking near 47 km/s. This higher velocity component, does possess enough energy to overcome typical energy losses and potentially contribute to the available energy of the observed coronal plasma. Title: Streamer belt - CME interactions: A case study for 2008 Authors: Lamb, D. A.; Kramar, M.; Davila, J. M. Bibcode: 2009AGUFMSH41B1668L Altcode: We investigate the origin of mass and influence of solar coronal mass ejections (CMEs) on the coronal streamer belt. The pre- and post-CME streamer belt structure from ~1.5 to 4 R⊙ are found by a tomographic reconstruction technique from STEREO B/COR1 data for the entire year 2008. These reconstructions allow us to make a case study for several CMEs during 2008. We find that the streamer belt frequently becomes notched at the time and location of a CME, indicating significant streamer mass loss. The notched structures are present for several days after some CME eruptions. A comparison of the mass lost by the streamer to the mass of a CME observed in the COR1 field of view can give a clue to the origin of the majority of the CME mass. Title: Solar Prominence Dynamics Prior to Eruption Authors: Kilper, G. K.; Davila, J. M. Bibcode: 2009AGUFMSH23B1542K Altcode: Solar prominence eruptions are extremely important phenomena due to their association with coronal mass ejections and their effects on space weather near Earth and throughout the solar system. Some insights into the eruption mechanism have been made via MHD modeling and observational studies, but comparisons between the models and observations have been inconclusive thus far. A coordinated observational study of prominence eruptions is being carried out to measure and compare various precursors to eruption that have been found in previous studies, including: heating of the material, emerging or canceling magnetic flux, increase in cavity size, and changes in the prominence mass and its composition. Our analysis examines the timing and the relative degree of these observational trends prior to eruption, and utilizes a wide range of observatories and instruments. Title: PROPAGATION AND EVOLUTION OF THE JUNE 1st 2008 CME IN THE INTERPLANETARY MEDIUM Authors: Nieves-Chinchilla, T.; Lamb, D. A.; Davila, J. M.; Vinas, A. F.; Moestl, C.; Hidalgo, M. A.; Farrugia, C. J.; Malandraki, O.; Dresing, N.; Gómez-Herrero, R. Bibcode: 2009AGUFMSH41A1626N Altcode: In this work we present a study of the coronal mass ejection (CME) of June 1st of 2008 in the interplanetary medium. This event has been extensively studied by others because of its favorable geometry and the possible consequences of its peculiar initiation for space weather forecasting. We show an analysis of the evolution of the CME in the interplanetary medium in order to shed some light on the propagation mechanism of the ICME. We have determined the typical shock associated characteristics of the ICME in order to understand the propagation properties. Using two different non force-free models of the magnetic cloud allows us to incorporate expansion of the cloud. We use in-situ measurements from STEREO B/IMPACT to characterize the ICME. In addition, we use images from STEREO A/SECCHI-HI to analyze the propagation and visual evolution of the associated flux rope in the interplanetary medium. We compare and contrast these observations with the results of the analytical models. Title: On the Origin, 3D Structure and Dynamic Evolution of CMEs Near Solar Minimum Authors: Xie, H.; St. Cyr, O. C.; Gopalswamy, N.; Yashiro, S.; Krall, J.; Kramar, M.; Davila, J. Bibcode: 2009SoPh..259..143X Altcode: We have conducted a statistical study 27 coronal mass ejections (CMEs) from January 2007 - June 2008, using the stereoscopic views of STEREO SECCHI A and B combined with SOHO LASCO observations. A flux-rope model, in conjunction with 3D triangulations, has been used to reconstruct the 3D structures and determine the actual speeds of CMEs. The origin and the dynamic evolution of the CMEs are investigated using COR1, COR2 and EUVI images. We have identified four types of solar surface activities associated with CMEs: i) total eruptive prominence (totEP), ii) partially eruptive prominence (PEP), iii) X-ray flare, and iv) X-type magnetic structure (X-line). Among the 27 CMEs, 18.5% (5 of 27) are associated with totEPs, 29.6% (8 of 27) are associated with PEPs, 26% (7 of 27) are flare related, and 26% (7 of 27) are associated with X-line structures, and 43% (3 of 7) are associated with both X-line structures and PEPs. Three (11%) could not be associated with any detectable activity. The mean actual speeds for totEP-CMEs, PEP-CMEs, flare-CMEs, and X-line-CMEs are 404 km s−1,247 km s−1,909 km s−1, and 276 km s−1, respectively; the average mean values of edge-on and broadside widths for the 27 CMEs are 52 and 85 degrees, respectively. We found that slow CMEs (V≤400 km s−1) tend to deflect towards and propagate along the streamer belts due to the deflections by the strong polar magnetic fields of corona holes, while some faster CMEs show opposite deflections away from the streamer belts. Title: On the Tomographic Reconstruction of the 3D Electron Density for the Solar Corona from STEREO COR1 Data Authors: Kramar, M.; Jones, S.; Davila, J.; Inhester, B.; Mierla, M. Bibcode: 2009SoPh..259..109K Altcode: We present for the first time a three-dimensional reconstruction of the electron density in the corona at distances from 1.5R to 4R using COR1 STEREO observations. The reconstruction is performed using a regularized tomography inversion method for two biweekly periods corresponding to Carrington Rotations 2058 and 2066. Images from the two STEREO spacecraft are used to compare the reconstructed density structures with coronal features located by triangulation. We find that the location of a bright tip of a helmet streamer obtained from the tomographic reconstruction is in good agreement with the location obtained by triangulation. The reconstructed density structure of the equatorial streamer belt is largely consistent with the variation of the current sheet derived from a potential magnetic field extrapolation for most of the equatorial region and for an MHD model of the corona. A zero-value density region in the reconstruction is identified with a low-density region seen in an EUVI image below the reconstruction domain. Title: On 3D Reconstruction of Coronal Mass Ejections: I. Method Description and Application to SECCHI-COR Data Authors: Mierla, M.; Inhester, B.; Marqué, C.; Rodriguez, L.; Gissot, S.; Zhukov, A. N.; Berghmans, D.; Davila, J. Bibcode: 2009SoPh..259..123M Altcode: The data from SECCHI-COR1 and SECCHI-COR2 coronagraphs onboard the STEREO mission, which was launched in October 2006, provide us with the first-ever stereoscopic images of the Sun's corona. These observations were found to be useful in inferring the three-dimensional structure of coronal mass ejections (CMEs) and their propagation direction in space. We apply four methods for reconstructing CMEs: i) Forward modeling technique; ii) Local correlation tracking (to identify the same feature in COR Ahead and COR Behind images) plus tie-point reconstruction technique; iii) Center of mass of the structures in a given epipolar plane plus tie-point reconstruction technique; iv) Polarization ratio technique. The four techniques are applied to three structured CMEs observed by COR1 and COR2 instruments, respectively, on 15 May 2007, 31 August 2007, and 25 March 2008. A comparison of the results obtained from the application of the four reconstruction algorithms is presented and discussed. Title: Relation Between Type II Bursts and CMEs Inferred from STEREO Observations Authors: Gopalswamy, N.; Thompson, W. T.; Davila, J. M.; Kaiser, M. L.; Yashiro, S.; Mäkelä, P.; Michalek, G.; Bougeret, J. -L.; Howard, R. A. Bibcode: 2009SoPh..259..227G Altcode: The inner coronagraph (COR1) of the Solar Terrestrial Relations Observatory (STEREO) mission has made it possible to observe CMEs in the spatial domain overlapping with that of the metric type II radio bursts. The type II bursts were associated with generally weak flares (mostly B and C class soft X-ray flares), but the CMEs were quite energetic. Using CME data for a set of type II bursts during the declining phase of solar cycle 23, we determine the CME height when the type II bursts start, thus giving an estimate of the heliocentric distance at which CME-driven shocks form. This distance has been determined to be ∼1.5Rs (solar radii), which coincides with the distance at which the Alfvén speed profile has a minimum value. We also use type II radio observations from STEREO/WAVES and Wind/WAVES observations to show that CMEs with moderate speed drive either weak shocks or no shock at all when they attain a height where the Alfvén speed peaks (∼3Rs - 4Rs). Thus the shocks seem to be most efficient in accelerating electrons in the heliocentric distance range of 1.5Rs to 4Rs. By combining the radial variation of the CME speed in the inner corona (CME speed increase) and interplanetary medium (speed decrease) we were able to correctly account for the deviations from the universal drift-rate spectrum of type II bursts, thus confirming the close physical connection between type II bursts and CMEs. The average height (∼1.5Rs) of STEREO CMEs at the time of type II bursts is smaller than that (2.2Rs) obtained for SOHO (Solar and Heliospheric Observatory) CMEs. We suggest that this may indicate, at least partly, the density reduction in the corona between the maximum and declining phases, so a given plasma level occurs closer to the Sun in the latter phase. In two cases, there was a diffuse shock-like feature ahead of the main body of the CME, indicating a standoff distance of 1Rs - 2Rs by the time the CME left the LASCO field of view. Title: Hinode/EIS observations of propagating low-frequency slow magnetoacoustic waves in fan-like coronal loops Authors: Wang, T. J.; Ofman, L.; Davila, J. M.; Mariska, J. T. Bibcode: 2009A&A...503L..25W Altcode: 2009arXiv0908.0310W Aims: We report the first observation of multiple-periodic propagating disturbances along a fan-like coronal structure simultaneously detected in both intensity and Doppler shift in the Fe xii 195 Å line with the EUV Imaging Spectrometer (EIS) onboard Hinode. A new application of coronal seismology is provided based on this observation.
Methods: We analyzed the EIS sit-and-stare mode observation of oscillations using the running difference and wavelet techniques.
Results: Two harmonics with periods of 12 and 25 min are detected. We measured the Doppler shift amplitude of 1-2 km s-1, the relative intensity amplitude of 3%-5% and the apparent propagation speed of 100-120 km s-1.
Conclusions: The amplitude relationship between intensity and Doppler shift oscillations provides convincing evidence that these propagating features are a manifestation of slow magnetoacoustic waves. Detection lengths (over which the waves are visible) of the 25 min wave are about 70-90 Mm, much longer than those of the 5 min wave previously detected by TRACE. This difference may be explained by the dependence of damping length on the wave period for thermal conduction. Based on a linear wave theory, we derive an inclination of the magnetic field to the line-of-sight about 59 ± 8°, a true propagation speed of 128 ± 25 km s-1 and a temperature of 0.7 ± 0.3 MK near the loop's footpoint from our measurements.

Appendix is only available in electronic form at http://www.aanda.org Title: Localized Plasma Density Enhancements Observed in STEREO COR1 Authors: Jones, Shaela I.; Davila, Joseph M. Bibcode: 2009ApJ...701.1906J Altcode: Measurements of solar wind speed in the solar corona, where it is primarily accelerated, have proven elusive. One of the more successful attempts has been the tracking of outward-moving density inhomogeneities in white-light coronagraph images. These inhomogeneities, or "blobs," have been treated as passive tracers of the ambient solar wind. Here we report on the extension of these observations to lower altitudes using the STEREO COR1 coronagraph, and discuss the implications of these measurements for theories about the origin of these features. Title: Uritsky, Davila, and Jones Reply: Authors: Uritsky, Vadim M.; Davila, Joseph M.; Jones, Shaela I. Bibcode: 2009PhRvL.103c9502U Altcode: A Reply to the Comment by N. W. Watkins, S. C. Chapman, and S. Rosenberg. Title: Electron Temperature Maps of Low Solar Corona: Results from the Total Solar Eclipse of 29 March 2006 in Libya Authors: Reginald, Nelson Leslie; Davila, J.; St. Cyr, C. Bibcode: 2009SPD....40.1403R Altcode: We conducted an experiment in conjunction with the total solar eclipse of 29 March 2006 in Libya that measured the coronal intensity through two filters centered at 3850 and 4100 Angstroms with bandwidths of 40 Angstroms. The purpose of these measurements was to obtain the intensity ratio through these two filters to determine the electron temperature. The instrument, Imaging Spectrograph of Coronal Electrons (ISCORE), consisted of an 8-inch f/10 Schmidt Cassegrain telescope with a thermoelectrically cooled CCD camera at the focal plane. Results show temperatures of 105 K close to the limb to 3 MK at 1.3 solar radii. In the poster we describe this novel technique, and we compare our results to other relevant measurements. This technique could be easily implemented on a space-based platform using a coronagraph to produce global maps of the electron temperature of the solar corona. Title: Analysis of Active Region and Quiet Sun Spectra from SERTS-99 Observations Authors: Coyner, Aaron J.; Davila, J. M.; Brosius, J. W.; Ofman, L. Bibcode: 2009SPD....40.1216C Altcode: The Solar EUV Research Telescope and Spectrograph is a rocket-based instrument that uses high resolution extreme ultraviolet spectra to investigate features in the solar corona and transition region. The 1999 flight occurred on 24 June 1999 and obtained spectra from both active regions and quiet sun regions on the solar disk covering a spectral bandpass 300-355 angstroms We report here the calibrated intensities and measured linewidths determined from the spatially-averaged spectra of both active regions and quiet sun regions respectively. In addition, we determine a distribution of non-thermal velocity components from the measured linewidths of the identified lines. This distribution provides a quantitative constraint on the available energy of non-thermal origin in the observed regions which is available for coronal heating. Title: Propagating Slow Magnetoacoustic Waves in Coronal Loops Observed by Hinode/EIS Authors: Wang, T. J.; Ofman, L.; Davila, J. M. Bibcode: 2009ApJ...696.1448W Altcode: 2009arXiv0902.4480W We present the first Hinode/EUV Imaging Spectrometer observations of 5 minute quasi-periodic oscillations detected in a transition-region line (He II) and five coronal lines (Fe X, Fe XII, Fe XIII, Fe XIV, and Fe XV) at the footpoint of a coronal loop. The oscillations exist throughout the whole observation, characterized by a series of wave packets with nearly constant period, typically persisting for 4-6 cycles with a lifetime of 20-30 minutes. There is an approximate in-phase relation between Doppler shift and intensity oscillations. This provides evidence for slow magnetoacoustic waves propagating upward from the transition region into the corona. We find that the oscillations detected in the five coronal lines are highly correlated, and the amplitude decreases with increasing temperature. The amplitude of Doppler shift oscillations decrease by a factor of about 3, while that of relative intensity decreases by a factor of about 4 from Fe X to Fe XV. These oscillations may be caused by the leakage of the photospheric p-modes through the chromosphere and transition region into the corona, which has been suggested as the source for intensity oscillations previously observed by Transition Region and Coronal Explorer. The temperature dependence of the oscillation amplitudes can be explained by damping of the waves traveling along the loop with multithread structure near the footpoint. Thus, this property may have potential value for coronal seismology in diagnostic of temperature structure in a coronal loop. Title: Propagating Slow Magnetoacoustic Waves in Coronal Loops Observed by Hinode/EIS Authors: Wang, Tongjiang; Ofman, L.; Davila, J. Bibcode: 2009SPD....40.3003W Altcode: We present two cases of propagating slow magnetoacoustic waves in coronal loops observed by Hinode/EIS. In the first case, the 5-min waves were detected in a transition-region line (He II) and five coronal lines (Fe X - Fe XV) at a plage region. We find that the oscillations detected in coronal lines are highly correlated, and the amplitude decreases with increasing temperature. These waves may be caused by the leakage of the p-modes through the chromosphere and transition region into the corona. The temperature dependence of the oscillation amplitudes can be explained by damping of the waves traveling along the loop with multithermal fine structure near the footpoint. In the second case, outwardly propagating (on the order of 100 km/s) quasi-periodic disturbances along a fan-like coronal structure were for the first time detected simultaneously in intensity and Doppler shift. The measured amplitudes for the oscillations are consistent with the interpretation in terms of slow magnetoacoustic waves rather than high-speed outflows. The waves contain multiple harmonics of the periods of 12 min and 25 min. Their origin is not clear. The damping length of these low-frequency waves is distinctly longer than that of 5 min waves previously detected by TRACE in the similar structure. A new application of coronal seismology is given based on this observation, with which the true sound speed and temperature near the loop's footpoint are estimated. The work of LO and TJW was supported by NRL grant N00173-06-1-G033. LO was also supported by NASA grant NNG06GI55G. Title: Constraints On Coronal Non-thermal Velocities From SERTS 1991-1997 Observations Authors: Coyner, Aaron J.; Davila, J. M.; Ofman, L. Bibcode: 2009SPD....40.1302C Altcode: The determination of non-thermal velocities from spectral line observations provide insight into the availability of additional energy sources within the observed regions of the corona. These non-thermal velocities can be attributed to waves, electron beams, turbulent motions among other potential sources. Observationally constraining these velocities directly limits the available energy for heating within the observed coronal regions. We present the determination of non-thermal velocity distributions from the 397 identified lines from the SERTS 1991-1997 flights covering the spectral range 171-355 angstroms along with the distributions for the 253 lines identified in active regions, the 102 lines from quiet sun regions, and 42 lines from off limb observations respectively. We find that for all four the velocity distributions peak at non-thermal velocities between 23-30 km/s independent of activity level suggesting that many of these non-thermal velocities are likely the result of non-thermal motions of cooling plasma visible in both active and quiet regions; however the active region distribution does exhibit a more pronounced high velocity tail with a secondary bump which could .be the result of a component resulting from heating of the coronal plasma. Title: On The 3D Structure of the Pre- and After CME Coronal Streamer Belt Authors: Kramar, Maxim; Davila, J.; Xie, H.; Antiochos, S. Bibcode: 2009SPD....40.2211K Altcode: We select several CME events and reconstruct the 3D coronal streamer belt configurations for the periods of time before and after the corresponded CMEs. The reconstructions are based on STEREO COR1 observations and made by using a regularized tomography technique (Kramar et al. 2009). For some CME we found noticeable changes in the streamer belt structure. Particularly, for a slow CME on June 1, 2008 (Robbrecht et al. 2009) we found that for a longitudinal range of about 10 degrees in Carrington longitude centered at the CME location, the height of the overlying streamer belt was significantly reduced. This reduction in height persisted for at least 14 days. The reconstruction of the streamer belt before and after the CME allows direct estimate of the mass lost. Also it was found that positions of this and some others CME correspond to regions in the streamer belt where the latter has a double structure (i.e. splitted into two parts). Title: STEREO Observations of Slow Coronal Mass Ejections Authors: Lamb, Derek; Davila, J. M. Bibcode: 2009SPD....40.2103L Altcode: We have studied the STEREO/COR1 coronal mass ejection (CME) catalog for the period January-September 2008. Many of the observed CMEs exhibit slow liftoff speeds, commonly taking over 24 hours for the entire CME to exit the COR1 field of view. We will present a detailed overview of these slowly rising CMEs and trace their evolution from the on-disk source region, where possible, through the field of view of both STEREO coronagraphs. This is a first step towards studying the evolution of these CMEs in interplanetary space. Title: On 3D Reconstruction of Coronal Mass Ejections using SECCHI-COR Data Authors: Mierla, M.; Inhester, B.; Marque, C.; Rodriguez, L.; Gissot, S.; Zhukov, A.; Berghmans, D.; Davila, J. Bibcode: 2009EGUGA..11.1145M Altcode: The data from SECCHI-COR1 and SECCHI-COR2 coronagraphs onboard STEREO mission which was launched in October 2006 provided us with the first-ever stereoscopic images of the Sun's corona. These observations were found to be extremely useful in reconstructing the 3D structure of coronal mass ejections (CMEs). We apply four methods for reconstructing the CMEs: 1) Local correlation tracking (to identify the same feature in COR Ahead and COR Behind images) plus tie-point reconstruction technique; 2) Center of mass of the structures along the line of sight (i.e. along each epipolar lines) plus tie-point reconstruction technique; 3) Polarization ratio technique (see for e.g. Moran and Davila 2004); 4) Forward modelling technique (see Thernisien et al. 2006). The four techniques are applied on three structured CMEs observed by COR1 and COR2 instruments on 15 May 2007, 31 August 2007 and 25 March 2008. A comparison of results obtained from the application of the four reconstruction algorithms is presented and discussed. Title: Universal processes in heliophysics Authors: Davila, Joseph M.; Gopalswamy, Nat; Thompson, Barbara J. Bibcode: 2009IAUS..257...11D Altcode: The structure of the Universe is determined primarily by the interplay of gravity which is dominant in condensed objects, and the magnetic force which is dominant in the rarefied medium between condensed objects. Each of these forces orders the matter into a set of characteristic structures each with the ability to store and release energy in response to changes in the external environment. For the most part, the storage and release of energy proceeds through a number of Universal Processes. The coordinated study of these processes in different settings provides a deeper understanding of the underlying physics governing Universal Processes in astrophysics. Title: EUV Wave Reflection from a Coronal Hole Authors: Gopalswamy, N.; Yashiro, S.; Temmer, M.; Davila, J.; Thompson, W. T.; Jones, S.; McAteer, R. T. J.; Wuelser, J. -P.; Freeland, S.; Howard, R. A. Bibcode: 2009ApJ...691L.123G Altcode: We report on the detection of EUV wave reflection from a coronal hole, as observed by the Solar Terrestrial Relations Observatory mission. The EUV wave was associated with a coronal mass ejection (CME) erupting near the disk center. It was possible to measure the kinematics of the reflected waves for the first time. The reflected waves were generally slower than the direct wave. One of the important implications of the wave reflection is that the EUV transients are truly a wave phenomenon. The EUV wave reflection has implications for CME propagation, especially during the declining phase of the solar cycle when there are many low-latitude coronal holes. Title: Putting the "I" in IHY: The United Nations Report for the International Heliophysical Year 2007 Authors: Thompson, Barbara J.; Gopalswamy, Natchimuthuk; Davila, Joseph M.; Haubold, Hans J. Bibcode: 2009piih.rept.....T Altcode: No abstract at ADS Title: Relation between Coronal Mass Ejection, Type II Radio Burst, and EUV Wave during the 2008 March 25 STEREO Event Authors: Gopalswamy, N.; Yashiro, S.; Akiyama, S.; Freeland, S.; Thompson, W. T.; Davila, J. M.; Howard, R. A.; Kaiser, M. L.; Bougeret, J. - Bibcode: 2008AGUFMSH12A..02G Altcode: STEREO and SOHO observations of the March 25, 2008 coronal mass ejection (CME) provide an excellent opportunity to study its early evolution from multiple view points. The CME was fast (980 km/s) and wide (112 degrees) from the east limb of the Sun as viewed by SOHO. The STEREO spacecraft were separated by about 50 degrees, so the CME was a disk event for the STEREO-behind spacecraft and a behind-the-limb event for STEREO-ahead. The CME was associated with a well defined EUV wave as observed by the STEREO/EUVI instrument, a metric type II burst, and a multi-component type II burst observed by the STEREO/WAVES and Wind/WAVES instruments. One of the important aspect of this CME is that it was well observed by STEREO/SECCHI inner coronagraph (COR1) when the metric type II burst was in progress, so we are able to obtain the shock height with respect t the CME. This enabled us to infer the connection the coronal shock driven by the CME (inferred from type II burst) and the EUV wave. It appears that the EUV wave steepened into a shock and produced the type II burst. The multiple components of the type II burst were not harmonically related, so we examined the circumstances of the eruption. CME was ejected in the region between two streamers, so the CME-driven shock is likely to simultaneously encounter high and low- density regions of the corona, thus producing type II bursts at widely separated frequencies. This paper summarizes these observations and explains how the CME, type II radio burst, and EUV waves all fit together. Title: Outreach activities during the 2006 total solar eclipse sponsored by the International Heliophysical Year Authors: Rabello Soares, M. C.; Rabiu, A. B.; Gopalswamy, N.; Thompson, B. J.; Davila, J. M.; Sobrinho, A. A. Bibcode: 2008AdSpR..42.1792R Altcode: The International Heliophysical Year (IHY) is an international program of scientific research to advance our understanding of the physical processes that govern the Sun, Earth and heliosphere. It has a strong educational component, linking research and education. Here, we describe the outreach activities during the 2006 total solar eclipse sponsored by IHY. Title: Electron temperatures and its bulk flow speeds in the low solar corona measured during the total solar eclipse on 29 March 2006 in Libya Authors: Reginald, N. L.; Davila, J. M.; St. Cyr, O. C.; Guhathakurta, M.; Hassler, D. M. Bibcode: 2008AGUFMSH13B1535R Altcode: We conducted an experiment that measured the K-coronal spectra in the visible wavelength region, simultaneously at multiple locations in the low solar corona in conjunction with the total solar eclipse on 29 March 2006 in Libya. The shapes of these measured K-coronal spectra were then matched with K-coronal models with different combinations of electron temperatures and electron bulk flow speeds to obtain the best fit. Results show electron temperatures and bulk flow speeds of 1.10 ± 0.05 MK, 103.0 ± 92.0 kms-1; 0.98 ± 0.12 MK, 0.0 + 10.0 kms-1; 0.70 ± 0.08 MK, 0.0 + 10.0 kms-1 at 1.1 R⊙ in the solar north, east and west, respectively, and 0.93 ± 0.12 MK, 0.0 + 10.0 kms-1 at 1.2R⊙ in the solar east, in agreement with expectations. The instrument used in this experiment, (MACS)for Multi Aperture Coronal Spectrograph, used fiber optics in the focal plane of a 12 inch Schmidt Cassegrain telescope that were positioned at the locations where the above results were obtained. The light from these fibers were then simulteously fed in to a spectrograph that contained only reflective optics for the purpose of enhancing the transmission of light in the blue end of the spectrum. This was important because steep intensity gradients occurred in this region, which distinguished between different K-coronal models. Title: Measuring Electron Temperature and Flow Speed using Thomson Scattered Emission from the Corona Observed with the Solar-C Coronagraph Authors: Davila, J. M.; Reginald, N.; St. Cyr, O. C.; Kuhn, J. Bibcode: 2008AGUFMSH11A..05D Altcode: A method for measuring the density, temperature, and velocity of coronal electrons was proposed by Reginald and Davila (2000) based on an extension the Thomson scattering theory of Cram (1976) to include flows. In this method the electron density is measured in the usual way (e.g. in LASCO or MkIV coronagraph images) by observing the total coronal intensity. The electron temperature and flow speed are obtained by obtaining ratios of spectral intensity measured in 50 A passbands or by fitting a portion of the spectrum to coronal models. Observations during the total solar eclipse of 2000 near Lusaka, Zambia demonstrated the feasibility of the method (Reginald et. al., 2003) using the first generation Multi-Aperture Coronal Spectrometer (MACS-1) instrument, and with the second-generation MACS in Libya in 2006 reasonable temperature and flow speeds were obtained. In this paper we continue this work by reporting on the results of new observations taken from the ground at the Solar-C coronagraph. Although eclipse measurements provide the best observation (nearly free of scattered light but with limited duration), the Solar-C coronagraph observations allowed several days of nearly continuous observation from which the repeatability and accuracy of the measurement could be determined. To deal with the increased atmospheric scatter, observations at Solar-C were done in polarized brightness (pB). Results will be reported in this talk. Title: Reconstruction of the solar corona from STEREO COR1 observations Authors: Kramar, M.; Davila, J.; Inhester, B. Bibcode: 2008AGUFMSH13B1534K Altcode: The COR1 instruments provide white light observations of the solar corona from 1.5 to 4 Rsun where the transition from closed to open coronal structures takes a place. The reconstruction is performed by the regularized tomography inversion method and gives a 3D distribution of the electron density in the corona from 1.5 to 4 Rsun. The method allows to reconstruct only structures which are stationary during an observation period, i.e. from quarter to half a solar rotation. Title: A Quick Method for Estimating the Propagation Direction of Coronal Mass Ejections Using STEREO-COR1 Images Authors: Mierla, M.; Davila, J.; Thompson, W.; Inhester, B.; Srivastava, N.; Kramar, M.; St. Cyr, O. C.; Stenborg, G.; Howard, R. A. Bibcode: 2008SoPh..252..385M Altcode: 2008SoPh..tmp..170M We describe here a method to obtain the position of a coronal moving feature in a three-dimensional coordinate system based on height - time measurements applied to STEREO data. By using the height - time diagrams from the two SECCHI-COR1 coronagraphs onboard STEREO, one can easily determine the direction of propagation of a coronal mass ejection (i.e., if the moving plasma is oriented toward or away from the Earth). This method may prove to be a useful tool for space weather forecasting by easily identifying the direction of propagation as well as the real speed of the coronal mass ejections. Title: STEREO and RHESSI Observations of Electron Acceleration in a Partially Disk-Occulted Solar Flare Authors: Krucker, S.; Wuelser, J. -P.; Vourlidas, A.; Davila, J.; Thompson, W. T.; White, S.; Lin, R. P. Bibcode: 2008ESPM...12.2.84K Altcode: RHESSI hard X-ray observations of partially-disk occulted solar flares provide crucial information on faint coronal hard X-ray sources in the absence of generally much brighter emissions from footpoints of flare loops. Coronal hard X-ray sources can differ fundamentally from the classical footpoint sources of the flare impulsive phase and provide unique information about the supra-thermal electrons closest to the site in the corona where their acceleration is believed to occur. The different view-angles provided by the STEREO spacecraft allow us to put the partially occulted hard X-ray sources observed by RHESSI in context with the EUV flare ribbons and the EUV emission from CME observed by STEREO/EUVI.

In this presentation we report on the GOES C8 flare observed on December 31, 2007 peaking around 01:11UT. From Earth-view (RHESSI), the flare occurs about 12 degrees behind the eastern limb giving an occultation height of 16 Mm. From STEREO B, the flare ribbons are seen on the disk (about 10 degrees from the limb), while the flare is highly occulted (130 Mm) for STEREO A observations so that emissions related to the associated CME are seen. Despite the occultation, RHESSI observes strong non-thermal emissions up to 100 keV that entirely originate from the corona. Initially, the coronal hard X-ray emission is seen from above the EUV flare ribbons similar to what is reported in the Masuda flare. Later on, emissions from a radially extended (approximately 20 Mm) source is seen. The radial extension is in the same direction as the current sheet of the outward moving CME suggesting that the HXR emission might be a direct signature of electrons accelerated in the reconnection process. Title: Emission lines of FeX in active region spectra obtained with the Solar Extreme-ultraviolet Research Telescope and Spectrograph Authors: Keenan, F. P.; Jess, D. B.; Aggarwal, K. M.; Thomas, R. J.; Brosius, J. W.; Davila, J. M. Bibcode: 2008MNRAS.389..939K Altcode: 2008MNRAS.tmp..860K; 2008arXiv0806.3354K Fully relativistic calculations of radiative rates and electron impact excitation cross-sections for FeX are used to derive theoretical emission-line ratios involving transitions in the 174-366Å wavelength range. A comparison of these with solar active region observations obtained during the 1989 and 1995 flights of the Solar Extreme-ultraviolet Research Telescope and Spectrograph (SERTS) reveals generally very good agreement between theory and experiment. Several FeX emission features are detected for the first time in SERTS spectra, while the 3s23p52P3/2-3s23p4(1S)3d 2D3/2 transition at 195.32Å is identified for the first time (to our knowledge) in an astronomical source. The most useful FeX electron density (Ne) diagnostic line ratios are assessed to be 175.27/174.53 and 175.27/177.24, which both involve lines close in wavelength and free from blends, vary by factors of 13 between Ne = 108 and 1011cm-3, and yet show little temperature sensitivity. Should these lines not be available, then the 257.25/345.74 ratio may be employed to determine Ne, although this requires an accurate evaluation of the instrument intensity calibration over a relatively large wavelength range. However, if the weak 324.73Å line of FeX is reliably detected, the use of 324.73/345.74 or 257.25/324.73 is recommended over 257.25/345.74. Electron densities deduced from 175.27/174.53 and 175.27/177.24 for the stars Procyon and α Cen, using observations from the Extreme-Ultraviolet Explorer (EUVE) satellite, are found to be consistent and in agreement with the values of Ne determined from other diagnostic ratios in the EUVE spectra. A comparison of several theoretical extreme-ultraviolet FeX line ratios with experimental values for a θ-pinch, for which the plasma parameters have been independently determined, reveals reasonable agreement between theory and observation, providing some independent support for the accuracy of the adopted atomic data. Title: Reconstruction of the coronal electron density at heights from 1.5 to 4 Rsun Authors: Kramar, M.; Jones, S.; Davila, J.; Inhester, B.; Mierla, M. Bibcode: 2008AGUSMSP31D..01K Altcode: We present a reconstruction of the electron density structure in the solar corona from 1.5 to 4 Rsun. The reconstruction is performed by the regularized tomography inversion method and based on the STEREO COR1 pB-images. The reconstruction is made for the period of relatively quite Sun. The reconstructed density structure of the equatorial streamer belt in a most of the reconstructed domain is consistent with the variation of the current sheet derived from a potential magnetic field model. However, there are also regions where this correlation is less clear. Title: The STEREO Mission: An Introduction Authors: Kaiser, M. L.; Kucera, T. A.; Davila, J. M.; St. Cyr, O. C.; Guhathakurta, M.; Christian, E. Bibcode: 2008SSRv..136....5K Altcode: 2007SSRv..tmp..198K The twin STEREO spacecraft were launched on October 26, 2006, at 00:52 UT from Kennedy Space Center aboard a Delta 7925 launch vehicle. After a series of highly eccentric Earth orbits with apogees beyond the moon, each spacecraft used close flybys of the moon to escape into orbits about the Sun near 1 AU. Once in heliospheric orbit, one spacecraft trails Earth while the other leads. As viewed from the Sun, the two spacecraft separate at approximately 44 to 45 degrees per year. The purposes of the STEREO Mission are to understand the causes and mechanisms of coronal mass ejection (CME) initiation and to follow the propagation of CMEs through the inner heliosphere to Earth. Researchers will use STEREO measurements to study the mechanisms and sites of energetic particle acceleration and to develop three-dimensional (3-D) time-dependent models of the magnetic topology, temperature, density and velocity of the solar wind between the Sun and Earth. To accomplish these goals, each STEREO spacecraft is equipped with an almost identical set of optical, radio and in situ particles and fields instruments provided by U.S. and European investigators. The SECCHI suite of instruments includes two white light coronagraphs, an extreme ultraviolet imager and two heliospheric white light imagers which track CMEs out to 1 AU. The IMPACT suite of instruments measures in situ solar wind electrons, energetic electrons, protons and heavier ions. IMPACT also includes a magnetometer to measure the in situ magnetic field strength and direction. The PLASTIC instrument measures the composition of heavy ions in the ambient plasma as well as protons and alpha particles. The S/WAVES instrument uses radio waves to track the location of CME-driven shocks and the 3-D topology of open field lines along which flow particles produced by solar flares. Each of the four instrument packages produce a small real-time stream of selected data for purposes of predicting space weather events at Earth. NOAA forecasters at the Space Environment Center and others will use these data in their space weather forecasting and their resultant products will be widely used throughout the world. In addition to the four instrument teams, there is substantial participation by modeling and theory oriented teams. All STEREO data are freely available through individual Web sites at the four Principal Investigator institutions as well as at the STEREO Science Center located at NASA Goddard Space Flight Center. Title: Sun Earth Connection Coronal and Heliospheric Investigation (SECCHI) Authors: Howard, R. A.; Moses, J. D.; Vourlidas, A.; Newmark, J. S.; Socker, D. G.; Plunkett, S. P.; Korendyke, C. M.; Cook, J. W.; Hurley, A.; Davila, J. M.; Thompson, W. T.; St Cyr, O. C.; Mentzell, E.; Mehalick, K.; Lemen, J. R.; Wuelser, J. P.; Duncan, D. W.; Tarbell, T. D.; Wolfson, C. J.; Moore, A.; Harrison, R. A.; Waltham, N. R.; Lang, J.; Davis, C. J.; Eyles, C. J.; Mapson-Menard, H.; Simnett, G. M.; Halain, J. P.; Defise, J. M.; Mazy, E.; Rochus, P.; Mercier, R.; Ravet, M. F.; Delmotte, F.; Auchere, F.; Delaboudiniere, J. P.; Bothmer, V.; Deutsch, W.; Wang, D.; Rich, N.; Cooper, S.; Stephens, V.; Maahs, G.; Baugh, R.; McMullin, D.; Carter, T. Bibcode: 2008SSRv..136...67H Altcode: 2008SSRv..tmp...64H The Sun Earth Connection Coronal and Heliospheric Investigation (SECCHI) is a five telescope package, which has been developed for the Solar Terrestrial Relation Observatory (STEREO) mission by the Naval Research Laboratory (USA), the Lockheed Solar and Astrophysics Laboratory (USA), the Goddard Space Flight Center (USA), the University of Birmingham (UK), the Rutherford Appleton Laboratory (UK), the Max Planck Institute for Solar System Research (Germany), the Centre Spatiale de Leige (Belgium), the Institut d’Optique (France) and the Institut d’Astrophysique Spatiale (France). SECCHI comprises five telescopes, which together image the solar corona from the solar disk to beyond 1 AU. These telescopes are: an extreme ultraviolet imager (EUVI: 1 1.7 R), two traditional Lyot coronagraphs (COR1: 1.5 4 R and COR2: 2.5 15 R) and two new designs of heliospheric imagers (HI-1: 15 84 R and HI-2: 66 318 R). All the instruments use 2048×2048 pixel CCD arrays in a backside-in mode. The EUVI backside surface has been specially processed for EUV sensitivity, while the others have an anti-reflection coating applied. A multi-tasking operating system, running on a PowerPC CPU, receives commands from the spacecraft, controls the instrument operations, acquires the images and compresses them for downlink through the main science channel (at compression factors typically up to 20×) and also through a low bandwidth channel to be used for space weather forecasting (at compression factors up to 200×). An image compression factor of about 10× enable the collection of images at the rate of about one every 2 3 minutes. Identical instruments, except for different sizes of occulters, are included on the STEREO-A and STEREO-B spacecraft. Title: Heliospheric Images of the Solar Wind at Earth Authors: Sheeley, N. R., Jr.; Herbst, A. D.; Palatchi, C. A.; Wang, Y. -M.; Howard, R. A.; Moses, J. D.; Vourlidas, A.; Newmark, J. S.; Socker, D. G.; Plunkett, S. P.; Korendyke, C. M.; Burlaga, L. F.; Davila, J. M.; Thompson, W. T.; St. Cyr, O. C.; Harrison, R. A.; Davis, C. J.; Eyles, C. J.; Halain, J. P.; Wang, D.; Rich, N. B.; Battams, K.; Esfandiari, E.; Stenborg, G. Bibcode: 2008ApJ...675..853S Altcode: During relatively quiet solar conditions throughout the spring and summer of 2007, the SECCHI HI2 white-light telescope on the STEREO B solar-orbiting spacecraft observed a succession of wave fronts sweeping past Earth. We have compared these heliospheric images with in situ plasma and magnetic field measurements obtained by near-Earth spacecraft, and we have found a near perfect association between the occurrence of these waves and the arrival of density enhancements at the leading edges of high-speed solar wind streams. Virtually all of the strong corotating interaction regions are accompanied by large-scale waves, and the low-density regions between them lack such waves. Because the Sun was dominated by long-lived coronal holes and recurrent solar wind streams during this interval, there is little doubt that we have been observing the compression regions that are formed at low latitude as solar rotation causes the high-speed wind from coronal holes to run into lower speed wind ahead of it. Title: SECCHI Observations of the Sun's Garden-Hose Density Spiral Authors: Sheeley, N. R., Jr.; Herbst, A. D.; Palatchi, C. A.; Wang, Y. -M.; Howard, R. A.; Moses, J. D.; Vourlidas, A.; Newmark, J. S.; Socker, D. G.; Plunkett, S. P.; Korendyke, C. M.; Burlaga, L. F.; Davila, J. M.; Thompson, W. T.; St. Cyr, O. C.; Harrison, R. A.; Davis, C. J.; Eyles, C. J.; Halain, J. P.; Wang, D.; Rich, N. B.; Battams, K.; Esfandiari, E.; Stenborg, G. Bibcode: 2008ApJ...674L.109S Altcode: The SECCHI HI2 white-light imagers on the STEREO A and B spacecraft show systematically different proper motions of material moving outward from the Sun in front of high-speed solar wind streams from coronal holes. As a group of ejections enters the eastern (A) field of view, the elements at the rear of the group appear to overrun the elements at the front. (This is a projection effect and does not mean that the different elements actually merge.) The opposite is true in the western (B) field; the elements at the front of the group appear to run away from the elements at the rear. Elongation/time maps show this effect as a characteristic grouping of the tracks of motion into convergent patterns in the east and divergent patterns in the west, consistent with ejections from a single longitude on the rotating Sun. Evidently, we are observing segments of the "garden-hose" spiral made visible when fast wind from a low-latitude coronal hole compresses blobs of streamer material being shed at the leading edge of the hole. Title: Study of a coronal mass ejection using STEREO/SECCHI and SOHO/LASCO observations Authors: Dal Lago, Alisson; Inhester, Bernd; Davila, Joseph; Antunes Vieira, Luis Eduardo Bibcode: 2008cosp...37..634D Altcode: 2008cosp.meet..634D The Solar Terrestrial Relations Observatory - STEREO was launched on October 25th, 2006 and is composed of two nearly identical spacecrafts, one ahead of Earth in its orbit, the other trailing behind. Its objective is to study the Sun and the nature of its coronal mass ejections, or CMEs. Each spacecraft has, among others, an instrument package called Sun Earth Connection Coronal and Heliospheric Investigation (SECCHI), which is composed by 4 sets of instruments: SECCHI EUVI: Extreme UltraViolet Imager; SECCHI COR1: Inner Coronagraph; SECCHI COR2: Outer Coronagraph; SECCHI HI: Heliospheric Imager. These instruments are able to study the evolution of CMEs from birth at the Sun's surface through the corona and interplanetary medium to its eventual impact at Earth. Since 1996, the Large Angle and Spectrometric Coronagraph (LASCO), abord the Solar and Heliospheric Observatory (SOHO), is able to observe the solar corona from 1.1 to 32 solar radii (LASCO C1, C2 and C3 field of view). This observation capability has improved substantialy since STEREO SECCHI package is able to observe from 1.4 solar radii up to 1 AU (earth orbit). In this work, we study the evolution of a CMEs occurred on January 8th 2007 from 1.4 to beyond 32 solar radii, usind observations from the SECCHI package. Since the SOHO is still in operation, and since STEREO was very close proximity of the earth during this event, we were able to compare measurements from both SECCHI and LASCO instruments for this same CME. Title: Science Eclipses Politics During 2006 U.S. Eclipse Expedition to Libya Authors: St. Cyr, O. C.; Davila, Joseph M.; Guhathakurta, Madhulika; Senseney, Robert S. Bibcode: 2007EOSTr..88..539S Altcode: A total eclipse of the Sun is one of the most spectacular phenomena of nature, and it provides a unique venue to gather valuable measurements of the Sun's corona that cannot otherwise be obtained. Since the time of the first American expedition to observe the 1780 eclipse during the American Revolutionary War-with the British granting the observation vessel safe passage to Maine's Penobscot Bay-the U.S. government has had a history of supporting scientific expeditions to remote eclipse sites under difficult conditions. A recent expedition to Libya to observe and study the 29 March 2006 eclipse continues that tradition. Title: Acquisition and Preparation of Data from Libya 2006 Total Solar Eclipse Authors: Nickerson, N. S.; St Cyr, O.; Reginald, N.; Davila, J. Bibcode: 2007AGUFMSH21A0284N Altcode: Global temperature and wind speed of free electrons in the solar corona can be measured using light from the visible portion of the electromagnetic spectrum. Davila et al (SH06, Fall 2007 AGU) describe the results of a spectrometric investigation using this technique. In this report we describe a second technique based on filtergrams, which permit the entire inner corona to be imaged using ratios of individual exposures. The data gathered during the total eclipse in Libya March 29, 2006 has provided an opportunity to make such a measurement. Preparation of the data as well as calibration of the instrument played a critical role in eliminating uncertainty and obtaining useful results. In this presentation we will discuss the details of this preparation and present preliminary results. Title: Remote Sensing of the Electron Temperature and the Solar Wind Speed Near the Sun Authors: Davila, J. M.; Reginald, N.; St. Cyr, O. C. Bibcode: 2007AGUFMSH22B..04D Altcode: In-situ observations provide detailed information on the state of the solar wind at a particular observation site. But observation of the global state of the solar wind would require many observation points strategically placed throughout the heliosphere. In this paper we report the results of a new optical experiment (the Multi-Aperture Coronal Spectrograph, MACS) to obtain the electron temperature and flow speed in the solar corona by observing the visible K-coronal spectrum during the total solar eclipse on 29 March 2006 in Libya. Results show electron temperatures of 1.10 ± 0.05, 0.98 ± 0.12, and 0.70 ± 0.08 MK, at 1.1 R\odot in the solar north, east and west, respectively, and 0.93 ± 0.12 MK, at 1.2 R\odot in the solar east. The corresponding speeds obtained are 103.0 ± 92.0, 0.0 + 10.0, 0.0 + 10.0, and 0.0 + 10.0 km-s-1. The outer corona, where the solar wind speed is high, is too faint to observe during an eclipse from the ground but it is easily observed from space. Using the technique demonstrated by MACS, the next generation of solar coronagraphs will be able to provide not just density, but also the temperature and flow speed of the solar wind in the inner corona. This information will improve our models of the heliosphere, and significantly increase our understanding of the solar wind. Title: Extraction of Faint Features From STEREO COR1 Data Authors: Jones, S. I.; Davila, J. M.; Mierla, M. Bibcode: 2007AGUFMSH32A0776J Altcode: In white light coronagraph data, many kinematic properties of coronal features are measured by eye. These kinds of measurements can be difficult or impossible for features whose brightness is comparable to the noise level of the images. This could present a particular problem for those attempting to study future events coincident in the two STEREO COR1 coronagraphs. As their angular separation increases it will be increasingly difficult to see events in both instruments, since brightness falls off quickly with distance from the plane of the sky. In this work we seek to extend the intensity range of features that can be studied in COR1 data to previously intractable signal levels, using an unusual image differencing method and an angular integration technique presented by Dal Lago et al (2004). Challenges inherent to using this scheme with COR1 data will be discussed and examples of such faint features in original and enhanced versions will be presented. Title: 3D Reconstruction of the Electron Density in the Corona from COR1 STEREO Observations Authors: Kramar, M.; Jones, S.; Davila, J.; Inhester, B. Bibcode: 2007AGUFMSH42A..07K Altcode: We present 3D reconstruction for the electron density in the corona based on the COR1 STEREO observations. The reconstruction is performed by using regularized tomography inversion method. Since the solar corona is optically thin, coronal observations are essentially integrated over the line-of-sight (LOS). It is therefore impossible to resolve the structure of the corona along the LOS if observations are provided from a single view direction. Observations from different view positions are necessary to reconstruct 3D coronal structure and is the essence of the tomography inversion method. When having observations only from a single view direction, a rigid rotation of the coronal density structures with the Sun about the ecliptic must be assumed in order to apply the tomography technique. As a consequence, only structures which are stationary over half a solar rotation can be reconstructed. The STEREO observations allow us to reduce this stationarity assumption. For reconstruction we choose a period when the Sun is relatively quite. However some active events occurred, and we need to skip the data for these events. Therefore, in order to stabilize the reconstruction, the smoothness factor was used as regularization constraint during the inversion. Title: Wavelength Determination for Solar Features Observed by the EUV Imaging Spectrometer on Hinode Authors: Brown, Charles M.; Hara, Hirohisa; Kamio, Suguru; Feldman, Uri; Seely, John F.; Doschek, George A.; Mariska, John T.; Korendyke, Clarence M.; Lang, James; Dere, Kenneth P.; Culhane, Len; Thomas, Roger J.; Davila, Joseph M. Bibcode: 2007PASJ...59S.865B Altcode: A wavelength calibration of solar lines observed by the high resolution EUV Imaging Spectrometer (EIS) on the Hinode satellite is reported. Spectral features of the quiet sun and of two mildly active areas were measured and calibrated. A listing of the stronger observed lines with identification of the leading contributor ions is presented. 41 lines are reported, with 90% identified. Wavelength precisions (2σ) of ±0.0031Å for the EIS short band and ±0.0029Å for the EIS long band are obtained. These lines, typical of 1-2 ×106 K plasmas, are recommended as standards for the establishment of EIS wavelength scales. The temperature of EIS varies by about 1D.5 C around the orbit and also with spacecraft pointing. The correlation of these temperature changes with wavelength versus pixel number scale changes is reported. Title: Coexistence of Self-Organized Criticality and Intermittent Turbulence in the Solar Corona Authors: Uritsky, Vadim M.; Paczuski, Maya; Davila, Joseph M.; Jones, Shaela I. Bibcode: 2007PhRvL..99b5001U Altcode: 2006astro.ph.10130U An extended data set of extreme ultraviolet images of the solar corona provided by the SOHO spacecraft is analyzed using statistical methods common to studies of self-organized criticality (SOC) and intermittent turbulence (IT). The data exhibit simultaneous hallmarks of both regimes: namely, power-law avalanche statistics as well as multiscaling of structure functions for spatial activity. This implies that both SOC and IT may be manifestations of a single complex dynamical process entangling avalanches of magnetic energy dissipation with turbulent particle flows. Title: The Early Life Of A Coronal Mass Ejection From SECCHI And SOHO Observations Authors: Gopalswamy, N.; Yashiro, S.; Davila, J. M.; Howard, R. A.; SECCHI/COR1 Team Bibcode: 2007AAS...210.2813G Altcode: 2007BAAS...39..324G One of the key advantages of STEREO/SECCHI is the inner coronagraph (COR1), which can observe CMEs in the coronal region where CMEs attain their maximum acceleration. The first CME observed by COR1 was on 2006 December 30. The CME was also observed by the C2 and C3 coronagraphs of SOHO. We compare the morphological and height-time histories between COR1 and SOHO/LASCO data. We find that the flux rope structure evolves significantly between the COR1 and LASCO/C2 FOVs, although we can track features to get a continuous height-time history of the CME. We find excellent agreement between the two sets of data which could be combined to obtain the kinematic properties of the CME. We also superposed a STEREO/COR1 image of the CME on a STEREO/EUVI image and SOHO/C2 image to compare the solar origin and morphology. The CME originated from the southwest quadrant of the Sun and was of flux-rope type moving with an average speed of 200 km/s and an acceleration of 6 m/s/s, with a characteristic two-ribbon structure and an extended post-eruption arcade. In addition to the similarity in CME features, there was excellent correspondence between the outlying streamers in the two coronagraph images. Title: The EUV Imaging Spectrometer for Hinode Authors: Culhane, J. L.; Harra, L. K.; James, A. M.; Al-Janabi, K.; Bradley, L. J.; Chaudry, R. A.; Rees, K.; Tandy, J. A.; Thomas, P.; Whillock, M. C. R.; Winter, B.; Doschek, G. A.; Korendyke, C. M.; Brown, C. M.; Myers, S.; Mariska, J.; Seely, J.; Lang, J.; Kent, B. J.; Shaughnessy, B. M.; Young, P. R.; Simnett, G. M.; Castelli, C. M.; Mahmoud, S.; Mapson-Menard, H.; Probyn, B. J.; Thomas, R. J.; Davila, J.; Dere, K.; Windt, D.; Shea, J.; Hagood, R.; Moye, R.; Hara, H.; Watanabe, T.; Matsuzaki, K.; Kosugi, T.; Hansteen, V.; Wikstol, Ø. Bibcode: 2007SoPh..243...19C Altcode: The EUV Imaging Spectrometer (EIS) on Hinode will observe solar corona and upper transition region emission lines in the wavelength ranges 170 - 210 Å and 250 - 290 Å. The line centroid positions and profile widths will allow plasma velocities and turbulent or non-thermal line broadenings to be measured. We will derive local plasma temperatures and densities from the line intensities. The spectra will allow accurate determination of differential emission measure and element abundances within a variety of corona and transition region structures. These powerful spectroscopic diagnostics will allow identification and characterization of magnetic reconnection and wave propagation processes in the upper solar atmosphere. We will also directly study the detailed evolution and heating of coronal loops. The EIS instrument incorporates a unique two element, normal incidence design. The optics are coated with optimized multilayer coatings. We have selected highly efficient, backside-illuminated, thinned CCDs. These design features result in an instrument that has significantly greater effective area than previous orbiting EUV spectrographs with typical active region 2 - 5 s exposure times in the brightest lines. EIS can scan a field of 6×8.5 arc min with spatial and velocity scales of 1 arc sec and 25 km s−1 per pixel. The instrument design, its absolute calibration, and performance are described in detail in this paper. EIS will be used along with the Solar Optical Telescope (SOT) and the X-ray Telescope (XRT) for a wide range of studies of the solar atmosphere. Title: Advances in Solar Coronagraphy Authors: Rabin, D.; St. Cyr, O. C.; Davila, J. M. Bibcode: 2007lyot.confE..18R Altcode: Could Bernard Lyot have imagined the protean forms in which his most notable invention, the coronagraph, would appear 75 years later? Could he have foreseen that the most widely used solar coronagraphs would be based in space, or that coronagraphs would seek to image planets and disks around other stars? Perhaps so - he was far more than a builder of creative instruments. I will discuss advances in solar coronagraphy since Lyot's time, in both the science that drives the observations and the technology that sustains them. Title: Results From Observations Taken During The Total Solar Eclipse of 2006 Authors: Davila, Joseph M.; Reginald, N.; St. Cyr, O. C.; Guhathakurta, M.; Hassler, D. Bibcode: 2007AAS...21010504D Altcode: 2007BAAS...39..231D Using the Multi-Aperture Coronal Spectrometer (MACS) we measured the K-coronal spectrum in the visible wavelength range at multiple locations in the low solar corona during the total solar eclipse, which occured on 29 March 2006 In Libya. The purpose of these measurements was to obtain the thermal electron temperature, and its flow speed at those locations. The observed K-coronal spectrum was matched with models to obtain the best fit to the data. These observations could be easily performed from a space-based platform to produce global maps of the electron density, temperature, and flow speed at the base of the solar wind. Title: Early Results from STEREO SECCHI COR1 Authors: St. Cyr, Orville C.; Davila, J. M.; Thompson, W.; Thompson, B. J.; Gurman, J. B.; Burkepile, J. T.; de Toma, G. Bibcode: 2007AAS...21011903S Altcode: 2007BAAS...39..243S With the successful launch and commissioning of STEREO, routine observations of the Sun's corona by the payload began in early 2007. The COR1 internally-occulted coronagraphs, which are classically-designed Lyot instruments covering 1.4-4.0 Rsun, are performing extremely well. More than two dozen coronal mass ejections (CMEs) were detected by COR1 in the first month of observations. As the STEREO spacecraft separate away from Earth, the MK4 coronameter at MLSO will provide a third vantage point for observations of the low corona. In this presentation we will show CME observations from COR1 and MK4, and we will describe the context of these new observations. Title: The Sun To The Earth, A Panoramic View From SECCHI: Overview Authors: Moses, John Daniel; Newmark, J.; Howard, R. A.; Plunkett, S.; Socker, D.; Wang, D.; Vourlidas, A.; Halain, J.; Harrison, R. A.; Eyles, C. J.; Davila, J.; Lemen, J.; Wuelser, J. Bibcode: 2007AAS...21011904M Altcode: 2007BAAS...39..244M The Sun Earth Connection Coronal and Heliospheric Investigation (SECCHI) is the remote sensing component of the STEREO mission to explore the source, initiation, and propagation through the heliosphere of Coronal Mass Ejections (CMEs). To achieve this goal, SECCHI must continuously observe CMEs from two different perspectives beginning with the pre-event coronal configuration and ending with the propagation of the event out of the inner heliosphere. Thus, each of the two STEREO observatories carries a suite of SECCHI telescopes with 5 different fields of view providing an uninterrupted view of coronal and Heliospheric phenomena from the solar chromosphere to 1 AU. This is the first panoramic view of the inner heliosphere dedicated to observing the spatial and temporal scales characteristic of CMEs at elongation angles from 0 to almost 90 degrees.

We present first results from the SECCHI imaging suite with emphasis on the unprecedented panoramic views of the heliosphere. We show direct observations of CMEs and the solar wind from initiation on the Sun throughout the inner heliosphere to 1 AU. The SECCHI suite performance exceeds that necessary to achieve the Level 1 STEREO science objectives. Thus, as the STEREO spacecraft separate to provide views from different directions we can anticipate breakthrough observations for issues currently unresolved by plane-of-sky projections through optically thin structures.

The most current information on SECCHI can be obtained from the STEREO mission website at http://stereo.gsfc.nasa.gov and the SECCHI website at http://secchi.nrl.navy.mil. The NRL participation in the STEREO mission is supported by NASA under S-13631-Y, and by the Office of Naval Research. Title: IHY - An International Cooperative Program Authors: Rabello-Soares, M. Cristina; Davila, J.; Gopalswamy, N.; Thompson, B. Bibcode: 2007AAS...210.5701R Altcode: 2007BAAS...39..167R The International Heliophysical Year (IHY) in 2007/2008 involves thousands of scientists representing over 70 nations. It consists of four distinct elements that will be described here.

Taking advantage of the large amount of heliophysical data acquired routinely by a vast number of sophisticated instruments aboard space missions and at ground-based observatories, IHY aims to develop the basic science of heliophysics through cross-disciplinary studies of universal processes by means of Coordinated Investigation Programs (CIPs).

The second component is in collaboration with the United Nations Basic Space Science Initiative (UNBSSI) and consists of the deployment of arrays of small, inexpensive instruments such as magnetometers, radio antennas, GPS receivers, etc. around the world to provide global measurements. An important aspect of this partnership is to foster the participation of developing nations in heliophysics research.

IHY coincides with the commemoration of 50 years of the space age that started with launch of Sputnik on October 4, 1957 and it is on the brink of a new age of space exploration where the Moon, Mars and the outer planets will be the focus of the space programs in the next years. As a result, it presents an excellent opportunity to create interest for science among young people with the excitement of discovery of space. The education and outreach program forms another cornerstone of IHY.

Last but not least, an important part of the IHY activities, its forth component, is to preserve the history and memory of IGY 1957. Title: The SECCHI Experiment on the STEREO Mission Authors: Howard, R. A.; Moses, J. D.; Vourlidas, A.; Newmark, J. S.; Socker, D. G.; Wang, D.; Plunkett, S. P.; Baugh, R.; McMullin, D. R.; Davila, J. M.; Thompson, W. T.; Lemen, J. R.; Wuelser, J.; Harrison, R. A.; Waltham, N. R.; Davis, C. J.; Eyles, C. J.; Defise, J.; Halain, J.; Bothmer, V.; Delaboudiniere, J.; Auchere, F.; Mercier, R.; Ravet, M. F. Bibcode: 2007AGUSMSH33A..01H Altcode: The Sun Earth Connection Coronal and Heliospheric Investigation (SECCHI) on the NASA Solar Terrestrial Relations Observatory (STEREO) mission is a suite of remote sensing instruments consisting of an extreme ultraviolet (EUV) imager, two white light coronagraphs, and two telescopes that comprise the heliospheric imager. SECCHI will observe coronal mass ejections (CMEs) from their birth at the sun, through the corona and into the heliosphere. A complete instrument suite is being carried on each of the two STEREO spacecraft, which will provide the first sampling of a CME from two vantage points. The spacecraft, launched 25 October 2006, are orbiting the Sun, one Ahead of the Earth and the other Behind, each separating from Earth at about 22 degrees per year. The varying separation means that we will have different observational capabilities as the spacecraft separate and therefore differing science goals. The primary science objectives all are focused on understanding the physics of the CME process their initiation, 3D morphology, propagation, interaction with the interplanetary medium and space weather effects. By observing the CME from multiple viewpoints with UV and coronagraphic telescopes and by combining these observations with radio and in-situ observations from the other instruments on STEREO as well as from other satellites and ground based observatories operating at the same time, answers to some of the outstanding questions will be obtained. We will show some of the initial results. Title: Reducing The Effects Of Spacecraft Jitter In Stereo Cor1 Images Authors: Jones, Shaela I.; Davila, J.; Cremades, H.; Kramar, M. Bibcode: 2007AAS...210.2809J Altcode: 2007BAAS...39..136J The STEREO mission was launched in Oct 2006, and has currently completed lunar swingbys. The instrument is operating normally, however spacecraft jitter causes an increase in scattered light on one side of the image and a decrease on the opposite side. Because it changes from one image to the next, this scattered light requires special processing on the ground. We present a method for reducing this effect using data from the Guide Telescope. Title: On the Regularized Tomography for the Solar Corona Authors: Kramar, Maxim; Jones, S.; Davila, J.; Inhester, B. Bibcode: 2007AAS...210.2802K Altcode: 2007BAAS...39..135K Since the solar corona is optically thin, coronal observations are essentially integrated over the line-of-sight (LOS). It is therefore impossible to resolve the structure of the corona along the LOS if observations are provided from a single view direction. Observations from different view positions are necessary to reconstruct 3D coronal structure and is the essence of the tomography inversion method. When having observations only from a single view direction, a rigid rotation of the coronal density structures with the Sun about the ecliptic must be assumed in order to apply the tomography technique. As a consequence, only structures which are stationary over half a solar rotation can be reconstructed. The STEREO observations allow us to reduce this stationarity assumption.

Depending on the size of the reconstructing domain, the number of the observations, data noise, etc, the reconstruction usually is not unique. To stabilize the solution, we introduce regularization into the inversion which is essentially a smoothness factor for the density reconstruction. The introduced regularization is not isotropic in order to prevent smoothing the radial structures often observed in the corona.

Unlike usual scalar field tomography, which is essentially two-dimensional, our regularization concept and also the tilt of the Sun's axis with respect to the ecliptic requires to perform operations over the entire 3D domain during every iteration, which increases the computational resources needed for the inversion. To increase computational performance and resolution of the reconstructing domain, we apply a MPI-parallelization for the inversion code. The code is going to be used with STEREO COR1 data. Title: Stereo Observations Of The Solar Corona Using The Secchi Experiment Authors: Plunkett, Simon P.; Howard, R. A.; Moses, J. D.; Vourlidas, A.; Socker, D.; Newmark, J.; Wang, D.; Baugh, R.; Davila, J.; Thompson, W.; St. Cyr, O. C.; Lemen, J.; Wuelser, J. P.; Harrison, R. A.; Waltham, N.; Davis, C. J.; Eyles, C. J.; Defise, J. M.; Halain, J. P.; Bothmer, V.; Delaboudiniere, J. P.; Auchere, F.; Mercier, R.; Ravet, M. F. Bibcode: 2007AAS...21011901P Altcode: 2007BAAS...39..243P The Sun Earth Connection Coronal and Heliospheric Investigation (SECCHI) on the NASA Solar Terrestrial Relations Observatory (STEREO) mission is a suite of remote sensing instruments consisting of an extreme ultraviolet (EUV) imager, two white light coronagraphs, and two telescopes that comprise the heliospheric imager. The main objective of SECCHI is to observe coronal mass ejections (CMEs) from their birth at the sun, through the corona and into the heliosphere. A complete instrument suite is being carried on each of the two STEREO spacecraft, which will provide the first sampling of a CME from two vantage points as the spacecraft separate from each other at the rate of about 45 degrees per year. We will show examples of some of the data and some of the initial stereo results. Title: The Sun To The Earth, A Panoramic View From SECCHI: CME Observations Through The Inner Heliosphere Authors: Newmark, Jeffrey; Moses, J. D.; Howard, R. A.; Plunkett, S.; Socker, D.; Wang, D.; Vourlidas, A.; Halain, J. P.; Harrison, R. A.; Eyles, C. J.; Davila, J.; Lemen, J.; Wuelser, J. P. Bibcode: 2007AAS...21011905N Altcode: 2007BAAS...39..244N The STEREO SECCHI telescope suite is returning unprecedented viewsvof the Sun and inner heliosphere. The SECCHI instruments on each of the two STEREO spacecraft are observing Coronal Mass Ejections (CMEs) from their initiation, through the corona, and into interplanetary space beyond the Earth's orbit. We present a first analysis of a CME throughout the inner heliosphere. We focus on the propagation characteristics of the CME and the morphological properties of the CME as viewed from STEREO.

This first glimpse of a CME in the heliosphere clearly demonstrates the anticipated scientific returns that future STEREO observations (at larger angular separations) of CMEs in interplanetary space will provide.

The most current information can be obtained on the STEREO mission website at http://stereo.gsfc.nasa.gov and the SECCHI website at http://secchi.nrl.navy.mil. The NRL participation on SECCHI is supported by NASA under S-13631-Y, and by the Office of Naval Research. Title: Fe XIII emission lines in active region spectra obtained with the Solar Extreme-Ultraviolet Research Telescope and Spectrograph Authors: Keenan, F. P.; Jess, D. B.; Aggarwal, K. M.; Thomas, R. J.; Brosius, J. W.; Davila, J. M. Bibcode: 2007MNRAS.376..205K Altcode: 2006astro.ph.12493K; 2007MNRAS.tmp...38K Recent fully relativistic calculations of radiative rates and electron impact excitation cross-sections for Fe XIII are used to generate emission-line ratios involving 3s23p2-3s3p3 and 3s23p2-3s23p3d transitions in the 170-225 and 235-450 Å wavelength ranges covered by the Solar Extreme-Ultraviolet Research Telescope and Spectrograph (SERTS). A comparison of these line ratios with SERTS active region observations from rocket flights in 1989 and 1995 reveals generally very good agreement between theory and experiment. Several new Fe XIII emission features are identified, at wavelengths of 203.79, 259.94, 288.56 and 290.81 Å. However, major discrepancies between theory and observation remain for several Fe XIII transitions, as previously found by Landi and others, which cannot be explained by blending. Errors in the adopted atomic data appear to be the most likely explanation, in particular for transitions which have 3s23p3d 1D2 as their upper level. The most useful Fe XIII electron-density diagnostics in the SERTS spectral regions are assessed, in terms of the line pairs involved being (i) apparently free of atomic physics problems and blends, (ii) close in wavelength to reduce the effects of possible errors in the instrumental intensity calibration, and (iii) very sensitive to changes in Ne over the range 108-1011 cm-3. It is concluded that the ratios which best satisfy these conditions are 200.03/202.04 and 203.17/202.04 for the 170-225 Å wavelength region, and 348.18/320.80, 348.18/368.16, 359.64/348.18 and 359.83/368.16 for 235-450 Å. Title: The United Nations Basic Space Science Initiative for IHY 2007 Authors: Gopalswamy, Nat; Davila, Joseph; Thompson, Barbara; Haubold, Hans Bibcode: 2007IAUSS...5..295G Altcode: No abstract at ADS Title: The United Nations Basic Space Science Initiative: the TRIPOD concept Authors: Kitamura, Masatoshi; Wentzel, Don; Henden, Arne; Bennett, Jeffrey; Al-Naimiy, H. M. K.; Mathai, A. M.; Gopalswamy, Nat; Davila, Joseph; Thompson, Barbara; Webb, David; Haubold, Hans Bibcode: 2007IAUSS...5..277K Altcode: 2006physics..10149K Since 1990, the United Nations is annually holding a workshop on basic space science for the benefit of the worldwide development of astronomy. Additional to the scientific benefits of the workshops and the strengthening of international cooperation, the workshops lead to the establishment of astronomical telescope facilities through the Official Development Assistance (ODA) of Japan. Teaching material, hands-on astrophysics material, and variable star observing programmes had been developed for the operation of such astronomical telescope facilities in an university environment. This approach to astronomical telescope facility, observing programme, and teaching astronomy has become known as the basic space science TRIPOD concept. Currently, a similar TRIPOD concept is being developed for the International Heliophysical Year 2007, consisting of an instrument array, data taking and analysis, and teaching space science. Title: The International Heliophysical Year Authors: Davila, Joseph M.; Gopalswamy, Nat; Thompson, Barbara J. Bibcode: 2007RoAJ...17....3D Altcode: No abstract at ADS Title: Investigating the state of the Sun-Earth system during extreme events: First science results of a worldwide online conference series Authors: Kozyra, J. U.; Shibata, K.; Fox, N. J.; Basu, S.; Coster, A. J.; Davila, J. M.; Gopalswamy, N.; Liou, K.; Lu, G.; Mann, I. R.; Pallamraju, D.; Paxton, L. J.; Peterson, W. K.; Talaat, E. R.; Weatherwax, A. T.; Young, C. A.; Zanetti, L. J. Bibcode: 2006AGUFMSA43A..01K Altcode: This presentation reports on new science results from an online conference entitled "Return to the Auroral Oval for the Anniversary of the IGY" designed to bring together researchers worldwide: (1) to investigate newly reported features in the auroral oval during substorms that occur in the main phase of superstorms and how these features map throughout geospace, (2) to explore implications for the state of the geospace system, (3) to identify signatures associated with this geospace state from equatorial to polar latitudes, (4) to investigate the unusual aspects of the solar sources, and (5) to understand how propagation from Sun to Earth modified the observed solar drivers. The main focus of the first conference is on worldwide data exchange, the construction of global data products and assimilative global views, and identifying coupled chains of events from sun-to-Earth. The collaborative conference data products and enhanced understanding of the observed features of the events will form the basis for a follow-on conference in 2007 focused primarily on theoretical studies and collaborative simulation efforts between modeling groups, observers and data analysts. This conference is the first in a series of sun-Earth connection online conferences, sponsored by CAWSES, IHY, eGY, ICESTAR, NASA/LWS, and NSF Atmospheric Science Programs, and designed to bring interdisciplinary researchers together with the vast developing cyber-infrastructure of large international data sets, high performance computing and advanced visualizations to address grand challenge science issues in a way not previously possible. Title: The SECCHI Experiment on the STEREO Mission Authors: Howard, R. A.; Moses, D.; Vourlidas, A.; Newmark, J.; Socker, D. G.; Plunkett, S.; Wang, D.; Baugh, R.; McMullin, D.; Davila, J.; St. Cyr, C.; Thompson, W. T.; Lemen, J.; Wuelser, J.; Harrison, R. A.; Waltham, N. R.; Davis, C.; Eyles, C. J.; Defise, J.; Halain, J.; Bothmer, V.; Delaboudiniere, J.; Auchere, F.; Mercier, R.; Ravet, M. Bibcode: 2006AGUFMSM12A..02H Altcode: The Sun Earth Connection Coronal and Heliospheric Investigation (SECCHI) on the NASA Solar Terrestrial Relations Observatory (STEREO) mission is a suite of remote sensing instruments consisting of an extreme ultraviolet (EUV) imager, two white light coronagraphs, and two telescopes that comprise the heliospheric imager. SECCHI will observe coronal mass ejections (CMEs) from their birth at the sun, through the corona and into the heliosphere. A complete instrument suite is being carried on each of the two STEREO spacecraft, which will provide the first sampling of a CME from two vantage points. The spacecraft will orbit the Sun, one Ahead of the Earth and the other Behind, each separating from Earth at about 22 degrees per year. The varying separation means that we will have different observational capabilities as the spacecraft separate and therefore differing science goals. The primary science objectives all are focused on understanding the physics of the CME process their initiation, 3D morphology, propagation, interaction with the interplanetary medium and space weather effects. By observing the CME from multiple viewpoints with UV and coronagraphic telescopes and by combining these observations with radio and in-situ observations from the other instruments on STEREO as well as from other satellites and ground based observatories operating at the same time, answers to some of the outstanding questions will be obtained. STEREO follows the very successful SOHO mission. SOHO's success was primarily due to the highly complementary nature of the instruments, but it was partly due to the very stable platform. The L1 orbit enables an extremely stable thermal environment and thus very stable pointing, as well as uninterrupted solar viewing. The STEREO will have both of these characteristics, but in addition will have multi-viewpoint viewing of CMEs, which will greatly enhance the many discoveries that SOHO data have produced. We have been developing techniques to interpret the observations from multiple viewpoints and to perform 3-dimensional deconvolution of the CME observations using forward modeling and inversion techniques. A continuous downlink of STEREO data will provide a low-resolution, real- time view from all of the instruments. The full data are downlinked once a day and will be available about 24 hours later. We will present some preliminary results from the instrument, which is expected to be launched in October/November, 2006 Title: Optics and mechanisms for the Extreme-Ultraviolet Imaging Spectrometer on the Solar-B satellite Authors: Korendyke, Clarence M.; Brown, Charles M.; Thomas, Roger J.; Keyser, Christian; Davila, Joseph; Hagood, Robert; Hara, Hirohisa; Heidemann, Klaus; James, Adrian M.; Lang, James; Mariska, John T.; Moser, John; Moye, Robert; Myers, Steven; Probyn, Brian J.; Seely, John F.; Shea, John; Shepler, Ed; Tandy, Jason Bibcode: 2006ApOpt..45.8674K Altcode: The Extreme-Ultraviolet Imaging Spectrometer (EIS) is the first of a new generation of normal-incidence, two-optical-element spectroscopic instruments developed for space solar extreme-ultraviolet astronomy. The instrument is currently mounted on the Solar-B satellite for a planned launch in late 2006. The instrument observes in two spectral bands, 170-210 Å and 250-290 Å. The spectrograph geometry and grating prescription were optimized to obtain excellent imaging while still maintaining readily achievable physical and fabrication tolerances. A refined technique using low ruling density surrogate gratings and optical metrology was developed to align the instrument with visible light. Slit rasters of the solar surface are obtained by mechanically tilting the mirror. A slit exchange mechanism allows selection among four slits at the telescope focal plane. Each slit is precisely located at the focal plane. The spectrograph imaging performance was optically characterized in the laboratory. The resolution was measured using the Mg iii and Ne iii lines in the range of 171-200 Å. The He ii line at 256 Å and Ne iii lines were used in the range of 251-284 Å. The measurements demonstrate an equivalent resolution of ∼2 arc sec⁡ on the solar surface, in good agreement with the predicted performance. We describe the EIS optics, mechanisms, and measured performance. Title: Co-existence of self-organized criticality and intermittent turbulence in the solar corona Authors: Uritsky, V.; Paczuski, M.; Davila, J. M.; Jones, S. Bibcode: 2006AGUFMSH13A0397U Altcode: Turbulence and self-organized criticality (SOC) represent two major paths of dynamical complexity in driven, extended nonlinear systems. We present direct observational evidence for co-existence of these phenomena in the magnetized plasma of the solar corona. Using an extended collection of SOHO EIT images, we apply two alternative numerical analysis methods - one for analyzing avalanche statistics of bursty dissipation events and the other for studying spatial intermittency in the coronal emission field. We find that the energy and lifetime statistics of bursty dissipation in the corona obey robust scaling laws over the entire range of the observed scales. In contrast to previous studies of flare statistics, this observation is made using a spatiotemporal event detection algorithm compatible with the definition of avalanches in SOC simulations. Next, by applying statistical tools developed in fluid turbulence, we show that the same time series of emission patterns exhibits multiscaling and extended self-similarity of higher order structure functions characteristic of intermittent turbulence. The observed scaling behaviors show only weak dependence on average solar activity level and have been identified under both solar minimum and maximum conditions. Title: IHY-CAWSES Data base Authors: Young, C. A.; Thompson, B. J.; Davila, J.; Gopalswamy, N. Bibcode: 2006ihy..workE..90Y Altcode: In partnership with the CAWSES (Climate And Weather of the Sun-Earth System) program, IHY is sponsoring a series of Virtual Workshops and a special IHY/CAWSES database to provide virtual access of data collected for IHY and CAWSES campaigns. The first of the virtual workshops occurred November 13-17, 2006, and had more than 200 online participants. Online presentation and discussion tools are being refined for future workshops. The IHY/CAWSES database provides a means of entering data into the Virtual Solar Observatory (to provide the maximum and easiest possible access to the data) while still maintaining a close connection to the other data sets used in IHY/CAWSES activities. Title: International Heliophysical Year (IHY) Overview: Science, Observatory Development, Outreach and History Authors: Davila, J. M. Bibcode: 2006ihy..workE..13D Altcode: In 1957 a program of international research, inspired by the International Polar Years of 1882-83 and 1932-33, was organized as the International Geophysical Year (IGY) to study global phenomena of the Earth and geospace. The IGY involved about 60,000 scientists from 66 nations, working at thousands of stations, from pole to pole to obtain simultaneous, global observations on Earth and in space. There had never been anything like it before. On the fiftieth anniversary of the International Geophysical Year an international program of scientific collaboration will be conducted called the International Heliophysical Year (IHY). Like it predecessors, the IHY will focus on fundamental global questions of Earth and space science. The goals of the IHY are to: 1. Develop the basic science of heliophysics through cross- disciplinary studies of universal processes. 2. Determine the response of terrestrial and planetary magnetospheres and atmospheres to external drivers. 3. Promote research on the Sun-heliosphere system outward to the local interstellar medium - the new frontier. 4. Foster international scientific cooperation in the study of heliophysical phenomena now and in the future. 5. Preserve the history and legacy of the IGY on its 50th Anniversary. 6. Communicate unique IHY results to the scientific community and the general public. The IHY will help us develop a deeper understanding of physical processes in the solar system through a program of comparative study of universal processes that affect the interplanetary and terrestrial environment. The study of energetic events in the solar system will pave the way for safe human space travel to the Moon and planets in the future, and it will serve to inspire the next generation of space physicists. Title: IHY/UNBSS Program: Success Stories Authors: Gopalswamy, N.; Davila, J.; Thompson, B. J.; Haubold, H. J. Bibcode: 2006ihy..workE..15G Altcode: The United Nations Office for Outer Space Affairs, through the IHY secretariat and the United Nations Basic Space Science Initiative (UNBSSI) is assisting scientists and engineers from all over the world in participating in the International Heliophysical Year (IHY) 2007. A major thrust of the IHY/UNBSSI program is to deploy arrays of small, inexpensive instruments such as magnetometers, radio telescopes, GPS receivers, etc. around the world to provide global measurements of ionospheric and heliospheric phenomena. The small instrument program is a partnership between instrument providers, and instrument hosts in developing countries. The lead scientist will provide the instruments (or fabrication plans for instruments) in the array; the host country will provide manpower, facilities, and operational support to obtain data with the instrument typically at a local university. Existing data bases and relevant software tools can be identified to promote space science activities in developing countries. Extensive data on space science have been accumulated by a number of space missions. Similarly, long-term data bases are available from ground based observations. These data can be utilized in ways different from originally intended for understanding the heliophysical processes. This paper provides an overview of the IHY/UNBSS program, its achievements and future plans. Title: Solar and Heliospheric Observatory/Large Angle Spectrometric Coronagraph Polarimetric Calibration Authors: Moran, Thomas G.; Davila, Joseph M.; Morrill, Jeff S.; Wang, Dennis; Howard, Russel Bibcode: 2006SoPh..237..211M Altcode: 2006SoPh..tmp...13M We present a polarimetric characterization and correction for the Solar and Heliospheric Observatory/Large Angle Spectrometric Coronagraph (SOHO/LASCO) C2 and C3 white light coronagraphs. By measuring the uncorrected polarization angles in solar minimum C2 coronal images, we have determined that the coronagraph acts as an optical phase retarder which converts a small fraction of the incoming radiation polarization from linear to circular. In addition, from the measurements of polarization angle in C3 coronal images we have determined that a component of the instrumentally scattered light in that instrument is polarized. We infer the retardation angle for C2 and compute the corresponding Mueller matrix, and determine the polarized stray light spatial profile in C3. The C2 Mueller matrix and C3 polarized stray light profiles are used to correct for instrumental effects in solar minimum coronal observations to obtain polarized brightness between two and thirty-two solar radii, which show deep polar coronal holes extending to the limit of the field of view. Title: The United Nations Basic Space Science Initiative for IHY 2007 Authors: Gopalswamy, N.; Davila, J. M.; Thompson, B. J.; Haubold, H. Bibcode: 2006IAUSS...5E..47G Altcode: The United Nations, in cooperation with national and international space-related agencies and organizations, has been organizing annual workshops since 1990 on basic space science, particularly for the benefit of scientists and engineers from developing nations. The United Nations Office for Outer Space Affairs, through the IHY Secretariat and the United Nations Basic Space Science Initiative (UNBSSI) will assist scientists and engineers from all over the world in participating in the International Heliophysical Year (IHY) 2007. A major thrust of the IHY/UNBSSI program is to deploy arrays of small, inexpensive instruments such as magnetometers, radio telescopes, GPS receivers, all-sky cameras, etc. around the world to provide global measurements of ionospheric and heliospheric phenomena. The small instrument program is envisioned as a partnership between instrument providers, and instrument hosts in developing countries. The lead scientist will provide the instruments (or fabrication plans for instruments) in the array; the host country will provide manpower, facilities, and operational support to obtain data with the instrument typically at a local university. Funds are not available through the IHY to build the instruments; these must be obtained through the normal proposal channels. However all instrument operational support for local scientists, facilities, data acquisition, etc will be provided by the host nation. It is our hope that the IHY/UNBSSI program can facilitate the deployment of several of these networks world wide. Existing data bases and relevant software tools that can will be identified to promote space science activities in developing countries. Extensive data on space science have been accumulated by a number of space missions. Similarly, long-term data bases are available from ground based observations. These data can be utilized in ways different from originally intended for understanding the heliophysical processes. This paper provides an overview of the IHY/UNBSS program, its achievements and future plans. Title: A Kopp-Pneuman-like Picture of Coronal Mass Ejections Authors: Spicer, D. S.; Sibeck, D.; Thompson, B. J.; Davila, J. M. Bibcode: 2006ApJ...643.1304S Altcode: A new coronal mass ejection (CME) picture is described that utilizes a number of attributes commonly found operating during magnetotail reconnection events. We first present key observational constraints any final model of CMEs must explain. We then describe how three-dimensional reconnection occurs in the magnetotail and how magnetotail reconnection helps explain a variety of observed CME attributes. We then argue why reconnection, as usually described in the literature, cannot explain the particle acceleration process that occurs during the CME/flare process. Instead we argue that it is the flow fields that are driven by the relaxation of the magnetic stresses due to reconnection that are ultimately the cause of particle acceleration. In particular, it is the electrons that make up the discharging field-aligned currents, which connect flow field-driven cross field inertial currents in the high corona with the chromosphere, that are in fact the high-energy electrons needed to explain flare ribbons and other high-energy emissions. We compute the expected electron fluxes from these current systems and find that they are of order those required. In addition, we discuss betatron acceleration during the dipolarization process that occurs when the flux rope/CME is ejected and how the hot particles generated during the dipolarization process can lead to traps in solar loops, thereby helping to explain long-duration events. Further, we examine whether particle acceleration by shocks can contribute to the mix. We also note that our new picture eliminates a number of paradoxes, specifically elimination of magnetic flux from the Sun and how the Aly conjecture is not of consequence in our picture. Finally, we examine what will be needed to numerically simulate our picture of a CME. Title: First Results from EUNIS-06 Authors: Rabin, Douglas M.; Thomas, R. J.; Davila, J. M. Bibcode: 2006SPD....37.0106R Altcode: 2006BAAS...38..216R The Extreme Ultraviolet Normal-Incidence Spectrograph (EUNIS) sounding rocket experiment successfully completed its first flight on 12 April 2006 from White Sands Missile Range, obtaining 145 science images in each of two wavelength channels. EUNIS is designed to investigate the energetics of the solar corona and hotter transition region through high-resolution imaging spectroscopy with a rapid (2-3 second) cadence. The two independent optical systems of EUNIS simultaneously record spectra over two passbands (170-205 Å and 300-370 Å), each spatially resolved along slit lengths of about 660 arcsec. The longwave channel includes He II 304 Å and strong lines from Fe XI-XVI. The shortwave passband has a sequence of very strong Fe IX-XIII lines. Together, the EUNIS telescopes furnish a wide range of temperature and density diagnostics and enables underflight calibration of instrumental passbands on the SOHO, TRACE, Solar-B, and STEREO missions.

We present an overview of the science images from the first flight with emphasis on transient phenomena. The target was active region NOAA 10871 and adjacent quiet areas. Spectra were recorded with exposure times as short as 0.1 s, demonstrating that EUNIS is the most sensitive solar EUV spectrograph in operation, with over 100 times the throughput of its predecessor, the Solar Extreme ultraviolet Research Telescope and Spectrograph (SERTS).

EUNIS is supported by the NASA Heliophysics Division's Solar & Heliospheric Physics Supporting Research and Technology and Low Cost Access to Space Program. Title: Ground-Based Low Coronal Electron Temperature And Its Flow Measurements During The Total Solar Eclipse On 29 March 2006 In Libya Authors: Reginald, Nelson L.; Davila, J. M.; St. Cyr, C. Bibcode: 2006SPD....37.0611R Altcode: 2006BAAS...38..227R We have developed ground based instruments that can simultaneously and globally measure the temperature and the flow speeds of the low coronal electrons during a total solar eclipse. These two instruments were successfully operated during the total solar eclipse on 29 March 2006 in Libya. In one instrument, MACS for Multi Aperture Coronal Spectrometer, fiber optics at the focal plane of a telescope carried visible coronal light from different latitudes and heights in the low solar corona to produce simultaneous spectra. The K-coronal spectra derived from these spectra can be used to derive the coronal electron temperature and its flow speed. In the other instrument, ISCORE for Imaging Spectroscopy of Coronal Electrons, images of the corona were produced through four filters centered at four wavelength positions in the visible region each with a bandpass of 50 Angstroms. Here the ratio of intensities of the K-coronal light from two of the filters would provide information on the coronal temperature, while the intensities through the other two filters would yield information on the flow speeds of the coronal electrons. While these two techniques compliment each other, together they can produce a global map of the coronal electron temperature and its flow speed in the low solar corona. Additionally it would also yield information on the electron acceleration. We are in the process of integrating this technique using the SolarC coronagraph located at the Mees Solar Observatory in Haleakala, Hawaii. If this proves to be successful then these techniques would yield these important coronal properties on demand. Title: A Sun-to-Earth Campaign Joining Observations from the Great Observatory with Worldwide Satellite and Ground-Based Resources to Investigate System Science Frontiers Authors: Kozyra, J. U.; Shibata, K.; Barnes, R. J.; Basu, S.; Davila, J. M.; Fox, N. J.; Gopalswamy, N.; Kuznetsova, M. M.; Pallamraju, D.; Paxton, L. J.; Ridley, A.; Weiss, M.; Young, C. A.; Zanetti, L. J. Bibcode: 2006AGUSMSM23A..03K Altcode: An Internet-based cross-disciplinary analysis campaign that will make heavy use of Great Observatory missions as well as international satellite and ground-based assets is being undertaken with joint support from the CAWSES, IHY, LWS, and ICESTAR programs planned for late April or early May 2006. An evolving list of open science questions that serve as sun-to-Earth focus areas for the worldwide campaign were identified during a small interdisciplinary CAWSES workshop at Stanford University in December 2005 as well as during a joint CAWSES/ICESTAR session at the CEDAR meeting in Boulder the preceding summer. The analysis campaign will take place over the Internet in the form of virtual poster sessions with message boards and monitors that summarize the important science issues and new results daily. Poster authors will be asked to closely monitor their message boards during the day of their poster session as well as the following day. Outreach to other disciplines and international students will take the form of tutorial talks that place campaign science issues into the context of the current state of knowledge in each discipline area. Global models and data sets (TEC, magnetometer maps, ULF wave maps, assimilative models, MHD model outputs, continuous solar images) will be available to provide context for local and regional observations. The Community Coordinated Data Center (CCMC) is developing a small number of new data display formats that extract data from global models and place it in the same format as the observations either for ground-based stations or along satellite tracks. Other ideas being explored include real time upload of additional posters in response to issues raised during the poster session, library of related articles, reference archive of observations, etc. A summary of which aspects and/or tools worked and which were less useful will be presented. Title: Science Plans for the International Heliophysical Year Authors: Davila, J. M.; Gopalswamy, N.; Harrison, R. A.; Stamper, R.; Briand, C.; Potgieter, M. S. Bibcode: 2006AGUSM.U34A..04D Altcode: On October 4, 1957, only 53 years after the beginning of flight in Kitty Hawk, the launch of Sputnik 1 marked the beginning of the space age; as mankind took the first steps to leaving the protected environment of Earth's atmosphere. Discovery of the radiation belts, the solar wind, and the structure of Earth's magnetosphere prepared the way for the inevitable human exploration to follow. Soon, Cosmonauts and Astronauts orbited Earth, and then in 1969, Astronauts landed on the Moon. Today a similar story is unfolding, the spacecraft Voyager has crossed the termination shock, and will soon leave the heliosphere. For the first time, man will begin to explore the local interstellar medium. It is inevitable that, during the next 50 years, exploration of the solar system including the Moon, Mars and the outer planets will be the focus of the space program, and like 50 years ago, unmanned probes will lead the way, followed by human exploration. The International Geophysical Year (IGY) of 1957, a broad-based and all-encompassing effort to push the frontiers of geophysics, resulted in a tremendous increase of knowledge in space physics, Sun-Earth Connection, planetary science and the heliosphere in general. Now, 50 years later, we have the unique opportunity to further advance our knowledge of the global heliosphere and its interaction with the interstellar medium through the International Heliophysical Year (IHY) in 2007, and to raise public awareness of space physics. This presentation will focus on global science planning efforts and campaigns for all participating IHY nations. Title: Planning the International Heliophysical Year (IHY) Authors: Davila, Joseph M.; Thompson, Barbara J.; Gopalswamy, Nat Bibcode: 2006UNPSA..17...37D Altcode: No abstract at ADS Title: The SECCHI Experiment on the STEREO Mission Authors: Howard, R.; Moses, D.; Vourlidas, A.; Davila, J.; Lemen, J.; Harrison, R.; Eyles, C.; Defise, J. -M.; Bothmer, V.; Ravet, M. -F.; Secchi Team Bibcode: 2006cosp...36..870H Altcode: 2006cosp.meet..870H The Sun Earth Connection Coronal and Heliospheric Investigation SECCHI on the NASA Solar Terrestrial Relations Observatory STEREO mission is a suite of remote sensing instruments consisting of an extreme ultraviolet EUV imager two white light coronagraphs and two telescopes that comprise the heliospheric imager SECCHI will observe coronal mass ejections CMEs from their birth at the sun through the corona and into the heliosphere A complete instrument suite is being carried on each of the two STEREO spacecraft which will provide the first sampling of a CME from two vantage points The spacecraft will orbit the Sun one Ahead of the Earth and the other Behind each separating from Earth at about 22 degrees per year The varying separation means that we will have different observational capabilities as the spacecraft separate and therefore differing science goals The primary science objectives all are focused on understanding the physics of the CME process - their initiation 3D morphology propagation interaction with the interplanetary medium and space weather effects By observing the CME from multiple viewpoints with UV and coronagraphic telescopes and by combining these observations with radio and in-situ observations from the other instruments on STEREO as well as from other satellites and ground based observatories operating at the same time answers to some of the outstanding questions will be obtained STEREO follows the very successful SOHO mission SOHO s success was primarily due to the highly complementary nature of the instruments but it was Title: Preparing for the International Heliophysical Year (IHY) 2007 Authors: Davila, J. M.; Gopalswamy, N.; Thompson, B. J. Bibcode: 2006ilws.conf..231D Altcode: The International Geophysical Year (IGY) of 1957, a broad-based and all-encompassing effort to push the frontiers of geophysics, resulted in a tremendous increase of knowledge in space physics, Sun-Earth Connection, planetary science and the heliosphere in general. Now, 50 years later, we have the unique opportunity to advance our knowledge of the global heliosphere and its interaction with planetary bodies and the interstellar medium through the International Heliophysical Year (IHY) in 2007. This will be an international effort, which will raise public awareness of space physics. Title: The IHY/United Nations Distributed Observatory Development Program Authors: Haubold, H.; Thompson, B. J.; Al-Naimiy, H.; Davila, J. M.; Gopalswamy, N.; Groves, K.; Scherrer, D. Bibcode: 2006cosp...36.3304H Altcode: 2006cosp.meet.3304H A major thrust of the International Heliophysical Year IHY is to deploy arrays of small inexpensive instruments such as magnetometers radio antennas GPS receivers all-sky cameras etc around the world to provide global measurements of ionospheric magnetospheric and heliospheric phenomena This program is a collaboration between the IHY and the United Nations Basic Space Science Initiative UNBSSI which has been dedicated to the IHY through 2009 The small instrument program consists of a partnership between instrument providers and instrument host countries The lead scientist provides the instrumentation or fabrication plans for instruments in the array the host country provides manpower facilities and operational support to obtain data with the instrument typically at a local university This program has been active in deploying instrumentation developing plans for new instrumentation and identifying educational opportunities for the host nations in association with this program We will discuss the program s status significant deployment activities and plans for 2007-2009 Title: International coordinated efforts for IHY 2007 Authors: Gopalswamy, N.; Davila, J.; Thompson, B. Bibcode: 2006cosp...36.2743G Altcode: 2006cosp.meet.2743G The International Heliophysical Year IHY in 2007 marks the enormous progress made since the International Geophysical Year IGY in 1957 The philosophy behind IHY is similar to that of IGY in studying the environment of our habitat except that the scope has increased to the physical space extending to the interstellar medium This paper describes the international organization of the IHY and planning for a successful program in 2007 In particular we describe the national regional and global efforts in pooling the resources to address the universal processes that govern the solar system and its interaction with the surrounding medium The efforts include identifying science questions of immediate concern and the data sets needed to address these questions The data will be acquired using a truly distributed observatory consisting of all the ground and space-based instruments that exist today and those to be constructed before 2007 The international planning also involves coordinating with the United Nations which through its Basic Space Science Initiative is facilitating the participation of the developing nations in the IHY program An update of the current status of the planning activities at the international level will be presented Title: The International Heliophysical Year (IHY) 2007 Authors: Davila, J. M.; Thompson, B. J.; Gopalswamy, N. Bibcode: 2006AfrSk..10....4D Altcode: The International Geophysical Year (IGY) of 1957, a broad-based and all-encompassing effort to push the frontiers of geophysics, resulted in a tremendous increase of knowledge in space physics, the Sun-Earth connection, planetary science, and the heliosphere in general. Now, fifty years later, we have the unique opportunity to advance our knowledge of the global heliosphere and its interaction with planetary bodies and the interstellar medium through the International Heliophysical Year (IHY) in 2007. This will be an international effort which will raise public awareness of space physics. Because of its unique geographic position, Africa is well-positioned to play a critical role. Title: A 3D Numerical Toolkit for Modeling the Heliosphere Authors: Spicer, D. S.; Davila, J. M.; Ofman, L. Bibcode: 2005AGUFMSH11A0258S Altcode: We present results from a numerical toolkit that can be used by observers, analysts, and modelers to study solar activity and its effect on the heliosphere. The core of the toolkit is a 3D AMR unstructured mesh high order Godunov code that was orginally designed to model the magnetospheric-ionospheric system. We plan to make the code available in portable code form through the CCMC. Title: First Results From EUNIS 2005 Authors: Rabin, D. M.; Thomas, R. J.; Davila, J. M.; Brosius, J. W.; Swartz, M.; Jordan, S. D. Bibcode: 2005AGUFMSH41B1122R Altcode: The Extreme Ultraviolet Normal-Incidence Spectrograph (EUNIS) is a sounding rocket experiment to investigate the energetics of the solar corona and hotter transition region through high-resolution imaging spectroscopy with a rapid (2 second) cadence. Pre-flight characterization of throughput has demonstrated that EUNIS is the most sensitive solar EUV spectrograph in existence, having over 100 times the throughput of its predecessor, the Solar Extreme ultraviolet Research Telescope and Spectrograph (SERTS). We report initial results from the first flight in November 2005 from White Sands Missile Range. The main scientific goal of the first EUNIS flight is to extend the investigation of transient phenomena, such as nanoflares and blinkers, to shorter timescales than has been possible with previous EUV spectrographs. The two independent optical systems of EUNIS record spatially co-aligned spectra over two passbands (170--205 Å and 300--370 Å) simultaneously with spectral resolution of 60 mÅ or 120 mÅ, respectively. The longwave passband includes He II 304 Å and strong lines from Fe XI--XVI. The shortwave passband has a sequence of very strong Fe IX--XIII lines. Together, the EUNIS telescopes furnish a wide range of temperature and density diagnostics and enable underflight calibration of instrumental passbands on the SOHO, TRACE, Solar-B, and STEREO missions. Title: Multi Aperture Coronal Spectrographic Technique for Simultaneous and Global Measurements of the Coronal Electron Temperature and its Bulk Flow Speed in the Low Solar Corona Authors: Reginald, N. L.; Davila, J. M.; St. Cyr, C. C. Bibcode: 2005AGUFMSH41B1123R Altcode: We describe a spectrographic technique that allows for the simultaneous and global measurements of the coronal electron temperature and its bulk flow speed in the low solar corona. This information is obtained through the measurement of the K-coronal spectrum in the 3900-4400 Angstrom region, whose shape is determined by the electron temperature and its bulk flow speed. The Multi Aperture Coronal Spectrograph allows for the simultaneous measurement of the K-coronal spectra all around the low solar corona (less than 2 solar radii). Since most of the coronal temperature and solar wind speed measurements in the literature are due to ion-based techniques, it is very important to verify that the electron-based measurements compliment the ion-based measurements. This is particularly important owing to the fact that electrons are almost 2000 times lighter than the protons. And if the electron-based measurement do not compliment the proton-based measurement then it is reasonable to explore the possibilities of these two oppositely charged particles being subject to different physical mechanisms in the solar corona. Title: Distributed Instrumentation Deployment During the IHY Authors: Davila, J. M.; Thompson, B. J.; Gopalswamy, N. Bibcode: 2005AGUFMSM21A0347D Altcode: A major thrust of the International Heliophysical Year (IHY) is to deploy arrays of small, inexpensive instruments such as magnetometers, radio antennas, GPS receivers, all-sky cameras, etc. around the world to provide global measurements of ionospheric and heliospheric phenomena. This program is a collaboration between the IHY and the United Nations Basic Space Science (UNBSS) program, which has been dedicated to the IHY through 2009. The small instrument program is envisioned as a partnership between instrument providers, and instrument host countries. The lead scientist will provide the instruments (or fabrication plans for instruments) in the array; the host country will provide manpower, facilities, and operational support to obtain data with the instrument typically at a local university. Instrument operational support for local scientists, facilities, data acquisition, etc will be provided by the host nation. Title: High-frequency Alfvén waves in multi-ion coronal plasma: Observational implications Authors: Ofman, L.; Davila, J. M.; Nakariakov, V. M.; ViñAs, A. -F. Bibcode: 2005JGRA..110.9102O Altcode: 2005JGRA..11009102O We investigate the effects of high-frequency (of order ion gyrofrequency) Alfvén and ion-cyclotron waves on ion emission lines by studying the dispersion of these waves in a multi-ion coronal plasma. For this purpose we solve the dispersion relation of the linearized multifluid and Vlasov equations in a magnetized multi-ion plasma with coronal abundances of heavy ions. We also calculate the dispersion relation using nonlinear one-dimensional hybrid kinetic simulations of the multi-ion plasma. When heavy ions are present the dispersion relation of parallel propagating Alfvén cyclotron waves exhibits the following branches (in the positive Ω - k quadrant): right-hand polarized nonresonant and left-hand polarized resonant branch for protons and each ion. We calculate the ratio of ion to proton velocities perpendicular to the direction of the magnetic field for each wave modes for typical coronal parameters and find strong enhancement of the heavy ion perpendicular fluid velocity compared with proton perpendicular fluid velocity. The linear multifluid cold plasma results agree with linear warm plasma Vlasov results and with the nonlinear hybrid simulation model results. In view of our findings we discuss how the observed nonthermal line broadening of minor ions in coronal holes may relate to the high-frequency wave motions. Title: Coronal electron velocity and temperature from Thomson scattered visible light Authors: Davila, Joseph M.; Reginald, Nelson L.; St. Cyr, O. C. Bibcode: 2005SPIE.5901...67D Altcode: The measurements of velocity and temperature of coronal electrons are of immense importance to the study of coronal dynamics, especially in the low solar corona. In this lies interesting physics yet to fully explain the theoretical reasoning for the million degree hot coronal plasma and the cause for the initial acceleration of this coronal plasma. In this regard it would be equally important if both of these coronal electron parameters, namely the velocity and the temperature of these coronal electrons, could be determined simultaneously and globally all around the low solar corona. The purpose of this paper is twin fold. First, to lay out an instrumental procedure that allows for the measurement of a coronal signature that could measure all around the low solar corona simultaneously. Second, to describe a theoretical procedure that allows for deriving both the coronal electron temperature and its bulk flow velocity from the measured coronal signature. Title: Fe XI Emission Lines in a High-Resolution Extreme-Ultraviolet Active Region Spectrum Obtained by the Solar Extreme Ultraviolet Research Telescope and Spectrograph Authors: Keenan, F. P.; Aggarwal, K. M.; Ryans, R. S. I.; Milligan, R. O.; Bloomfield, D. S.; Brosius, J. W.; Davila, J. M.; Thomas, R. J. Bibcode: 2005ApJ...624..428K Altcode: 2005astro.ph..4106K New calculations of radiative rates and electron impact excitation cross sections for Fe XI are used to derive emission-line intensity ratios involving 3s23p4-3s23p33d transitions in the 180-223 Å wavelength range. These ratios are subsequently compared with observations of a solar active region obtained during the 1995 flight of the Solar Extreme Ultraviolet Research Telescope and Spectrograph (SERTS). The version of SERTS flown in 1995 incorporated a multilayer grating that enhanced the instrumental sensitivity for features in the ~170-225 Å wavelength range, observed in second order between 340 and 450 Å. This enhancement led to the detection of many emission lines not seen on previous SERTS flights, which were measured with the highest spectral resolution (0.03 Å) ever achieved for spatially resolved active region spectra in this wavelength range. However, even at this high spectral resolution, several of the Fe XI lines are found to be blended, although the sources of the blends are identified in the majority of cases. The most useful Fe XI electron density diagnostic line intensity ratio is I(184.80 Å)/I(188.21 Å). This ratio involves lines close in wavelength and free from blends, and it varies by a factor of 11.7 between Ne=109 and 1011 cm-3 yet shows little temperature sensitivity. An unknown line in the SERTS spectrum at 189.00 Å is found to be due to Fe XI, the first time (to our knowledge) this feature has been identified in the solar spectrum. Similarly, there are new identifications of the Fe XI 192.88, 198.56, and 202.42 Å features, although the latter two are blended with S VIII/Fe XII and Fe XIII, respectively. Title: STEREO's Interactions With the Virtual Solar and Heliospheric Observatories Authors: Thompson, W. T.; Kaiser, M. L.; Kucera, T. A.; Davila, J. M.; Hourcle, J.; Schroeder, P. Bibcode: 2005AGUSMSH43B..06T Altcode: STEREO (Solar TErrestrial RElations Observatory) will observe the Sun and solar storms with two nearly identical spacecraft in heliocentric orbits, one ahead of Earth, the other trailing behind. This multi-spacecraft approach provides both stereoscopic views of the solar corona with the imaging telescopes, and multipoint observations of the heliosphere with the in-situ and radio experiments. Combined analysis with other viewpoints will be essential to STEREO science. Data archived at the NASA/GSFC STEREO Science Center will be completely integrated into the Virtual Solar Observatory (VSO), with shared resources and personnel. The in-situ and radio data will also be directly available through the Virtual Heliospheric Observatory (VHO). This dual system will ensure the maximum visibility of STEREO data to both the imaging and particle/field communities. Linkages between the VSO and VHO will allow all the STEREO data to be available through either system. Event lists will enhance the data set, and ease the data selection process. Title: Putting the Rubber to the Road: The Whos, Whys and Hows of the International Heliophysical Year 2007 Authors: Thompson, B. J.; Davila, J. M.; Drobnes, E.; Gopalswamy, N.; Wesenberg, R. P. Bibcode: 2005AGUSM.U23A..07T Altcode: In 1957 a program of international research, inspired by the International Polar Years of 1882 and 1932, was organized as the International Geophysical Year (IGY) to study global phenomena of the Earth and geospace. Fifty years later, the world's science community will again come together for international programs of scientific collaboration: the International Heliophysical Year (IHY), the electronic Geophysical Year (eGY), and the International Polar Year (IPY) 2007. This time, research will extend out into the heliosphere to focus on solar-terrestrial-planetary interactions. The ambitious plans for the IHY, eGY and IPY incorporate the activities of scientists in 191 nations, the "IGY Gold" Historical Preservation initiative, a series of coordinated campaigns involving more than 100 instruments and models, education and public outreach programs, a developing nations instrument development program, and opportunities for supported research worldwide. The presentation will focus on the efforts and operations which will make these activities possible. Title: Scientific Studies Using MACS: Coronal Reconnection Measurements and Solar Wind Acceleration Diagnostics Authors: St. Cyr, O. C.; Davila, J. M.; Reginald, N. L.; Brosius, J.; Moran, T. Bibcode: 2005AGUSMSP51B..03S Altcode: We have developed an instrument and an observational technique that exploits the shape of the K-coronal visible spectrum, 380-450 nm, to determine simultaneously both the thermal electron temperature and its bulk flow speed (see Reginald et al poster, this conference). For a given electron density along the line of sight, the shape of the K-coronal visible spectrum is influenced by the thermal electron temperature and its bulk flow speed. The bulk flow speed of the coronal electrons in the solar wind causes a Doppler-shift in the shape of the K-coronal spectrum depending on the magnitude of the speed. The simple reason for the red shift is that the wavelength-independent Thomson scattered coronal electrons observe a red-shifted photosphere as they move away from the Sun at the bulk flow speed. In addition, recent models have shown that identical streamers could be distinguished through their influence on the shape of the K-coronal visible spectrum in different wavelength regions. Modeling efforts have expanded to include a scenario where the observing line of sight passes through a coronal reconnection area. Using realistic parameters for the reconnection, and assuming that it produces bulk electron flows both toward and away from the Sun, our preliminary results indicate that the resulting red and blue-shifted K-coronal spectrum should be detectable with the MACS instrument. Title: MACS for global measurements of the thermal electron temperature and its bulk flow speed in the low solar corona through ground based experiments Authors: Reginald, N. L.; Davila, J. M.; St. Cyr, C.; Brosius, J. W.; Moran, T.; Thomas, R. Bibcode: 2005AGUSMSP51B..04R Altcode: The determination of the radial and latitudinal temperature and wind profiles of the solar corona is of immense importance in understanding the coronal heating mechanism and the dynamics of the coronal features. We have built MACS-1 (Multi Aperture Coronal Spectrometer); a fiber optic based spectrograph, to study the coronal properties during the total solar eclipses of August 1999 in Elazig, Turkey and June 2001 in Lusaka, Zambia, through the measurement of the K-coronal spectrum. In these experiments we have successfully demonstrated the feasibility of simultaneously measuring both the thermal electron temperature and its bulk flow speed at multiple locations on the solar corona. Measurement of these properties radially in the solar corona could provide valuable information on the solar wind acceleration in the low corona. We are now in the process of conducting a similar experiment on the low solar corona with an advanced spectrograph MACS-2 interfaced with the SolarC coronagraph at the Mees Solar Observatory in Haleakala, Hawaii. This if proven successful would provide an ability to measure simultaneously and globally the above coronal properties on demand. Title: Emission lines of FeXV in spectra obtained with the Solar Extreme-Ultraviolet Research Telescope and Spectrograph Authors: Keenan, F. P.; Aggarwal, K. M.; Milligan, R. O.; Ryans, R. S. I.; Bloomfield, D. S.; Srigengan, V.; O'Mullane, M. G.; Lawson, K. D.; Msezane, A. Z.; Brosius, J. W.; Davila, J. M.; Thomas, R. J. Bibcode: 2005MNRAS.356.1592K Altcode: 2004MNRAS.tmp..752K Recent R-matrix calculations of electron impact excitation rates in Mg-like FeXV are used to derive theoretical emission-line ratios involving transitions in the 243-418 Åwavelength range. A comparison of these with a data set of solar active region, subflare and off-limb spectra, obtained during rocket flights by the Solar Extreme-Ultraviolet Research Telescope and Spectrograph (SERTS), reveals generally very good agreement between theory and observation, indicating that most of the FeXV emission lines may be employed with confidence as electron density diagnostics. In particular, the 312.55-Åline of FeXV is not significantly blended with a CoXVII transition in active region spectra, as suggested previously, although the latter does make a major contribution in the subflare observations. Most of the FeXV transitions which are blended have had the species responsible clearly identified, although there remain a few instances where this has not been possible. We briefly address the long-standing discrepancy between theory and experiment for the intensity ratio of the 3s21S-3s3p 3P1 intercombination line at 417.25 Åto the 3s21S-3s3p 1P resonance transition at 284.16 Å. Title: Calibration Results for the COR-1 Coronagraph on STEREO/SECCHI Authors: Thompson, W. T.; Davila, J. M.; Mentzell, E.; Korendyke, C. Bibcode: 2004AGUFMSH21B0408T Altcode: COR-1 is the inner coronagraph of the Sun Earth Connection Coronal and Heliospheric Investigation (SECCHI) instrument suite aboard the two STEREO spacecraft. COR-1 is a classic Lyot internally occulting coronagraph, observing the solar corona in broadband red light around 656 nm, from 1.35 to 4 solar radii. A linear polarizer is used to suppress scattered light, and to extract the polarized brightness signal from the solar corona. Calibration was performed in the Naval Research Laboratory vacuum tunnel facility previously used for the LASCO experiment aboard SOHO. We report on the results for scattered light, photometric calibration, resolution, and polarization. All performance requirements are met or exceeded. Based on these results, we demonstrate that COR-1 will be able to carry out its scientific mission. Title: The Effects of Streamers on the Shape of the K-Coronal Spectrum Authors: Reginald, Nelson L.; Davila, Joseph M.; Cyr, O. C. St. Bibcode: 2004SoPh..225..249R Altcode: We conducted an experiment in conjunction with the total solar eclipse of 21 June 2001 in Lusaka, Zambia, to obtain the K-coronal spectrum simultaneously from multiple locations on the solar corona. Then we matched the observed K-coronal spectra with the modeled K-coronal spectra to determine the coronal electron temperature and its bulk flow speed. Here the models assumed a symmetric and isothermal corona with the coronal electron flowing away from the Sun at a constant flow speed. We were able to make remarkable matches between the observations and the models. In this paper we will try to explain how the anomalies in the matches could be accounted for with the introduction of streamers in the K-coronal spectral models. Title: Three-Dimensional Polarimetric Imaging of Coronal Mass Ejections Authors: Moran, Thomas G.; Davila, Joseph M. Bibcode: 2004Sci...305...66M Altcode: We present three-dimensional reconstructions of coronal mass ejections (CMEs), which were obtained through polarization analysis of single-view images recorded with the use of the Large Angle and Spectrometric Coronagraph (LASCO) C2 coronagraph on board the Solar and Heliospheric Observatory (SOHO) spacecraft. Analysis of a loop-like CME shows a complex three-dimensional structure centered at 40° from the plane of the sky, moving radially at 250 kilometers/second. Reconstruction of two halo CMEs suggests that these events are expanding loop arcades. Title: Development of MHD Wave Diagnostic and Models of Coronal Active Regions Authors: Ofman, L.; Thompson, B. J.; Davila, J. M. Bibcode: 2004AAS...204.9504O Altcode: 2004BAAS...36..826O We investigate the generation, propagation, and damping of MHD waves in active regions, with the goal to develop a diagnostic tool of active region structure, dynamics, and stability. We used 3D MHD model to study the generation and the propagation of EIT waves in a simple model of an active regions, and the interaction of EIT waves with the active region magnetic field. We model the oscillation of active region loops numerically using the 3D MHD model active regions. Such oscillations have been recently observed by TRACE. We use photospheric magnetograms as the boundary conditions for the magnetic field model, and construct an initial field using force-free extrapolation. Finite plasma temperature, density, and gravity are included in the model. We construct loop density structures in the model, guided by TRACE and EIT observations in the EUV. We demonstrate that by comparing the results of the MHD models of waves in an active region to observations we will be able to construct a diagnostic tool for the physical properties of the active regions, such as magnetic field and density structure. Title: Polarimetric Three-Dimensional Imaging of Coronal Mass Ejections Authors: Moran, T.; Davila, J. Bibcode: 2004AAS...204.1808M Altcode: 2004BAAS...36..683M We present the first three-dimensional reconstructions of coronal mass ejections (CMEs), which were obtained through polarization analysis of images recorded using the LASCO C2 coronagaph on board the SOHO spacecraft. The ratio of polarized-to-unpolarized electron-scattered emission is primarily a function of the angle between a radial through the scattering point and the plane-of-the-sky. Since the projected distance from sun center to the scattering point can be obtained from total brightness images, the brightness ratio measurement determines the point's distance from sun center and from the plane-of-the-sky. A topographical map is computed from the brightness ratio, from which 'top' and 'side' views of the CME are constructed. Three dimensional structure, position and velocity are computed for two CMEs, moving at 45 degrees and at 7 degrees from the Earth-Sun line. Analysis of the Earth-directed, or 'Halo' CME, shows a bilateral symmetry, indicating a loop arcade structure. The central loops are oriented vertically, while those at the ends tilt away from the arcade midplane. This work was funded by the NASA SR & T program. Title: Technique for simultaneous and global measurements of coronal electron temperature and solar wind speed in the lower corona Authors: Reginald, N. L.; Davila, J. M.; St. Cyr, O. C.; Brosius, J. W. Bibcode: 2004AAS...204.7302R Altcode: 2004BAAS...36..800R We have successfully demonstrated the feasibility of measuring both the coronal electron temperature and its radial flow speed simultaneously at multiple locations in the lower solar corona.

This experiment was conducted in conjunction with the total solar eclipse of 21 June 2001 using multiple fiber optic spectroscopic technique. Here one end of the multiple fibers was located at fixed radii at different latitudes in the focal plane of the telescope. The coronal light gathered by these fibers was then simultaneously fed to a spectroscope.

The required results were obtained by isolating the K-coronal spectrum in the 350-450 nm regions.

Our future plans are to locate fibers along radii to measure the acceleration of the electron flow speed in the lower corona. For this we intend to use this methodology in conjunction with the SolarC coronagraph at the Mees Solar Observatory in Haleakala, Hawaii. This would enable us to overcome the time constraints associated with eclipse observations.

The new design for the spectrograph envisages all reflective optics to minimize scattering, specialized chemical coatings to maximize capture of signal in the 350-450 nm regions and to pass the beam through a polarizer to account for the F-coronal component. Title: A Comparison of Theoretical Si <Emphasis Type="SmallCaps">VIII</Emphasis> Emission Line Ratios with Observations from Serts Authors: Keenan, F. P.; Katsiyannis, A. C.; Ramsbottom, C. A.; Bell, K. L.; Brosius, J. W.; Davila, J. M.; Thomas, R. J. Bibcode: 2004SoPh..219..251K Altcode: Recent R-matrix calculations of electron impact excitation rates in N-like Si VIII are used to derive theoretical emission line intensity ratios involving 2s22p3-2s2p4 transitions in the 216-320 Å wavelength range. A comparison of these with an extensive dataset of solar active region, quiet-Sun, sub-flare and off-limb observations, obtained during rocket flights of the Solar EUV Research Telescope and Spectrograph (SERTS), indicates that the ratio R1= I(216.94 Å)/I(319.84 Å) may provide a usable electron density diagnostic for coronal plasmas. The ratio involves two lines of comparable intensity, and varies by a factor of about 5 over the useful density range of 108-1011 cm−3. However R2= I(276.85 Å)/I(319.84 Å) and R3=I(277.05 Å)/I(319.84 Å) show very poor agreement between theory and observation, due to the severe blending of the 276.85 and 277.05 Å lines with Si VII and Mg VII transitions, respectively, making the ratios unsuitable as density diagnostics. The 314.35 Å feature of Si VIII also appears to be blended, with the other species contributing around 20% to the total line flux. Title: International heliophysical year: a program of global research continuing the tradition of previous international years Authors: Davila, Joseph M.; Poland, Arthur I.; Harrison, Richard A. Bibcode: 2004AdSpR..34.2453D Altcode: In 1957 a program of international research, inspired by the International Polar Years of 1882-1883 and 1932-1933, was organized as the International Geophysical Year (IGY) to study global phenomena of the Earth and geospace. The IGY involved about 60,000 scientists from 66 nations, working at thousands of stations from pole to pole, in an effort to obtain simultaneous, global observations on Earth and in space. There had never been anything like it before. The 50th anniversary of the International Geophysical Year will occur in 2007. We propose to organize an international program of scientific collaboration for this time period called the International Heliophysical Year (IHY). Like its predecessors, the IHY will focus on fundamental global questions of Earth science. Title: The Secchi Experiment on the Stereo Mission Authors: Howard, R.; Moses, D.; Socker, D.; Cook, J.; Davila, J.; Lemen, J.; Harrison, R.; Eyles, C.; Waltham, N.; Defise, J. -M. Bibcode: 2004cosp...35.3893H Altcode: 2004cosp.meet.3893H The Sun Earth Connection Coronal and Heliospheric Investigation (SECCHI) on the NASA Solar Terrestrial Relations Observatory (STEREO) mission is a suite of remote sensing instruments consisting of two white light coronagraphs, an extreme ultraviolet (EUV) imager, and a heliospheric imager. SECCHI will observe coronal mass ejections (CMEs) from their birth at the sun, through the corona and into the heliosphere. A complete instrument suite is being carried on each of the two STEREO spacecraft, which will provide the first sampling of a CME from two vantage points. The spacecraft will orbit the Sun, one ahead of the Earth and the other behind, separating from Earth at about 22 degrees per year. The varying separation means that we will have different observational capabilities as the spacecraft separate and therefore differing science goals. The primary science objectives all are focused on understanding the physics of the CME process - their initiation, 3D morphology, propagation, interaction with the interplanetary medium and space weather effects. By observing the CME from multiple viewpoints with UV and coronagraphic telescopes and by combining these observations with radio and in-situ observations from the other instruments on STEREO as well as from other satellites and ground based observatories operating at the same time, answers to some of the outstanding questions will be obtained. Title: Alfvén Waves in Multi-ion Coronal Plasma: Observational Implications Authors: Ofman, L.; Nakariakov, V. M.; Davila, J. M. Bibcode: 2003AGUFMSH11D1129O Altcode: We investigate low-frequency Alfvén waves in a multi-ion coronal plasma by deriving the dispersion relation of the linearized three-fluid equations in magnetized plasma with coronal parameters. We study the effect of collisions on the velocity amplitude of minor ions due to the Alfvén waves compared to the proton wave amplitude. We find that in the collisionless plasma the minor ion velocity is reduced by the factor Z/A compared to protons, where Z is the ion charge, and A is mass in units of proton mass. When the collision frequency is much larger then the Alfvén wave frequency the velocity amplitude of the minor ions is equal to the proton velocity amplitude. We show the effects of minor ions and collisions on the dispersion relation of Alfvén waves in the three fluid plasma. In view of our results we show how the observed nonthermal line broadening of minor ions relates to the wave motions of protons as a function of heliocentric distance, and the plasma physical parameters. Title: Electron Temperature and Speed Measurements in the Low Solar Corona: Results From the 2001 June Eclipse Authors: Reginald, Nelson L.; Cyr, O. C. St.; Davila, Joseph M.; Brosius, Jeffrey W. Bibcode: 2003ApJ...599..596R Altcode: We present measurements of electron temperature and bulk flow speed low in the solar corona derived from white-light spectra obtained during the total solar eclipse of 2001 June 21. Observations were obtained at two locations in the solar corona, one within a helmet streamer at the east limb and the second in a streamer cluster in the southwest. Both points were at an altitude of about 1.1 Rsolar from the solar center. The east limb and southwest locations yielded electron temperatures of 0.96+/-0.05 and 1.2+/-0.2 MK and bulk flow speeds of 72.0+281.0-72.0 and 257.0+443.0-257.0 km s-1, respectively. These measurements are unique in that they simultaneously provide both the electron temperature and its bulk flow speed; few previous measurements of electron parameters in the corona are available. The results presented here demonstrate the potential for this technique: if the instrument were used with a coronagraph, it would provide routine synoptic maps of electron temperature and bulk flow speed. Title: Development of 2D MHD Self-Consistent Empirical Model of the Corona and Solar Wind Authors: Sittler, E. C.; Ofman, L.; Gibson, S.; Holzer, T.; Davila, J.; Guhathakurta, M. Bibcode: 2003AGUFMSH42D..07S Altcode: We are developing a 2D MHD self-consistent empirical model of the solar corona and solar wind. We constrain the solution using empirically determined estimates of the effective pressure for the momentum equation and effective heat flux for the energy equation provided from coronagraph data and Ulysses plasma and magnetic field data. Our solutions are steady state and do not use a polytrope which we know is not valid in the solar corona. We have been able to achieve preliminary convergence. We will present the results of an error analysis. Our results are presently only valid during solar minimum, but are generalizing so it can be used during the transition toward solar maximum (i.e., three current sheets). We will also present some preliminary results which will allow us to apply our solutions to solar maximum conditions. Title: Development of Multidimensional MHD Model for the Solar Corona and Solar Wind Authors: Sittler, E. C.; Ofman, L.; Gibson, S.; Guhathakurta, M.; Davila, J.; Skoug, R.; Fludra, A.; Holzer, T. Bibcode: 2003AIPC..679..113S Altcode: We are developing a time stationary self-consistent 2D MHD model of the solar corona and solar wind that explicitly solves the energy equation, using a semi-empirical 2D MHD model of the corona to provide an empirically determined effective heat flux qeff (i.e., the term effective means the possible presence of wave contributions). But, as our preliminary results indicate, in order to achieve high speed winds over the poles we also need to include the empirically determined effective pressure Peff as a constraint in the momentum equation, which means that momentum addition by waves above 2 RS are required to produce high speed winds. At present our calculations do not include the Peff constraint. The estimates of Peff and qeff come from the semi-empirical 2D MHD model of the solar corona by Sittler and Guhathakurta (1999a,2002) which is based on Mk-III, Skylab and Ulysses observations. For future model development we plan to use SOHO LASCO, CDS, EIT, UVCS and Ulysses data as constraints for our model calculations. The model by Sittler and Guhathakurta (1999a, 2002) is not a self-consistent calculation. The calculations presented here is the first attempt at providing a self-consistent calculation based on empirical constraints. Title: Emission lines of Na-like ions in spectra obtained with the Solar EUV Research Telescope and Spectrograph (SERTS) Authors: Keenan, F. P.; Katsiyannis, A. C.; Brosius, J. W.; Davila, J. M.; Thomas, R. J. Bibcode: 2003MNRAS.342..513K Altcode: Theoretical emission-line ratios involving transitions in the 236-412 Å wavelength range are presented for the Na-like ions ArVIII, CrXIV, MnXV, FeXVI, CoXVII, NiXVIII and ZnXX. A comparison of these with an extensive data set of the solar active region, quiet-Sun, subflare and off-limb observations, obtained during rocket flights by the Solar EUV Research Telescope and Spectrograph (SERTS), reveals generally very good agreement between theory and experiment. This indicates that most of the Na-like ion lines are reliably detected in the SERTS observations, and hence may be employed with confidence in solar spectral analyses. However, the features in the SERTS spectra at 236.34 and 300.25 Å, originally identified as the NiXVIII 3p 2P3/2-3d 2D3/2 and CrXIV 3p 2P3/2-3d 2D5/2 transitions, respectively, are found to be due to emission lines of ArXIII (236.34 Å) and possibly SV or NiVI (300.25 Å). The CoXVII 3s 2S-3p 2P3/2 line at 312.55 Å is always badly blended with an FeXV feature at the same wavelength, but MnXV 3s 2S-3p 2P1/2 at 384.75 Å may not always be as affected by second-order emission from FeXII 192.37 Å as previously thought. On the other hand, we find that the ZnXX 3s 2S-3p 2P3/2 transition can sometimes make a significant contribution to the ZnXX/FeXIII 256.43-Å blend, and hence care must be taken when using this feature as an FeXIII electron density diagnostic. A line in the SERTS-89 active region spectrum at 265.00 Å has been re-assessed, and we confirm its identification as the FeXVI 3p 2P3/2-3d 2D3/2 transition. Title: Electron Temperature and Speed Measurements in the Lower Solar Corona: Results from the June 2001 Eclipse Authors: Reginald, N. L.; St. Cyr, O. C.; Davila, J. M.; Brosius, J. W. Bibcode: 2003SPD....34.0408R Altcode: 2003BAAS...35..811R The determination of the radial and latitudinal temperature and solar wind speed profiles of the solar corona is of immense importance in understanding the coronal heating mechanism and the dynamics of the coronal features. Cram (Sol. Phys, 48, 3, 1976) provided the theory for the formation of the K-coronal spectrum and a method for determining the radial profile of the coronal temperature.

We have modified Cram's theory to incorporate the role of the solar wind in the formation of the K-corona and have identified both temperature and speed sensitive intensity ratios. We built MACS (Multi Aperture Coronal Spectrometer); a fiber optic based spectrograph to study the total solar eclipse of June 2001 in Lusaka, Zambia. In this instrument one end of the five fiber-optic tips at the focal plane of the telescope were positioned to see different latitudes at the same radii on the solar corona. The other ends of the fibers were vertically aligned and placed at the primary focus of the collimating lens of the spectrograph.

We have succeeded in isolating the K-corona from the spectral observations made through two different fibers in MACS to match the theoretical K-coronal profiles for different temperatures and wind speeds. Results were obtained at two locations in the solar corona, one within a helmet streamer at the east limb and the second in a streamer cluster in the southwest. Both points were at an altitude of about 0.1-0.2 Rsun above the solar limb. The east limb location at the edge of a helmet streamer and the southwest location yielded electron temperatures of 0.94 +/- 0.01 MK and 1.28 +/- 0.02 MK and bulk flow speeds of 124.0 +/- 48.0 km/sec and 149.0 +/- 59.0 km/sec, respectively. This mechanism provides for simultaneous measurement of both the temperature and wind speed in the field of view of an exposed fiber to the corona. We will also present the details of this experiment. Title: The Extreme Ultraviolet Normal Incidence Spectrograph (EUNIS) Authors: Rabin, D.; Davila, J.; Thomas, R. J.; Engler, C.; Irish, S.; Keski-Kuha, R.; Novello, J.; Nowak, M.; Payne, L.; Rodriguez, I.; Saha, T.; Scott, R.; Swartz, M.; Trimble, M.; White, L.; Seshadri, S. Bibcode: 2003SPD....34.2007R Altcode: 2003BAAS...35..845R EUNIS is a high-efficiency extreme ultraviolet spectrometer that is expected to fly for the first time in 2004 as a sounding rocket payload. Using two independent optical systems, EUNIS will probe the structure and dynamics of the inner solar corona high spectral resolution in two wavelength regions: 17-21 nm with 3.5 pm resolution and 30-37 nm with 7 pm resolution. The long wavelength channel includes He II 30.4 nm and strong lines from Fe XI-XVI; the short wavelength channel includes strong lines of Fe IX-XIII. Angular resolution of 2 arcsec is maintained along a slit covering a full solar radius.

EUNIS will have 100 times the throughput of the highly successful SERTS payloads that have preceded it. There are only two reflections in each optical channel, from the superpolished, off-axis paraboloidal primary and the toroidal grating. Each optical element is coated with a high-efficiency multilayer coating optimized for its spectral bandpass. The detector in each channel is a microchannel plate image intensifier fiber-coupled to three 1K x 1K active pixel sensors.

EUNIS will obtain spectra with a cadence as short as 1 sec, allowing unprecedented studies of the physical properties of evolving and transient structures. Diagnostics of wave heating and reconnection wil be studied at heights above 2 solar radii, in the wind acceleration region. The broad spectral coverage and high spectral resolution will provide superior temperature and density diagnostics and will enable underflight calibration of several orbital instruments, including SOHO/CDS and EIT, TRACE, Solar-B/EIS, and STEREO/EUVI.

EUNIS is supported by NASA through the Low Cost Access to Space Program in Solar and Heliospheric Physics. Title: Nanoflare Frequency Distribution Scaling from Wave Heating: Results of Nonlinear Loop Modeling Authors: Davila, J. M.; Ofman, L.; Davila, J. M.; Ofman, L. Bibcode: 2003SPD....34.1601D Altcode: 2003BAAS...35..832D The statistics of nanoflare events observed by TRACE in the EUV and Yohkoh in soft X-rays exhibits a power law relation between the peak thermal energy and the number of events per energy interval. Using 1D coronal loop model with nonlinear coupling to the chromosphere (Ofman, Klimchuk, and Davila 1998) we calculate the distribution of heating events due to the dissipation of waves driven by a random Alfven wave source. Initial results show that the number of heating events per energy bin scale with energy with the power of 2+/- 0.4. The scaling is consistent with the observed value of 1.86+/-0.07 at 171Å and 1.81+/-0.10 at 195Å found with TRACE (Aschwanden and Parnell 2002). Thus, we conclude that in the nanonflare energy range (E<1028 erg) the observed frequency distribution of peak energy is consistent with wave heating. Title: Electron Temperature and Speed Measurements In the Low Solar Corona: Results from the June 2001 Eclipse Authors: Reginald, N. L.; St. Cyr, O. C.; Davila, J. M.; Brosius, J. W. Bibcode: 2003EAEJA....11383R Altcode: The determination of the radial and latitudinal temperature and solar wind speed profiles of the solar corona is of immense importance in understanding the coronal heating mechanism and the dynamics of the coronal features. Cram (Sol. Phys, 48,3, 1976) provided the theory for the formation of the K-coronal spectrum and a method for determining the radial profile of the coronal temperature. A slit-based spectroscopic study was performed by Ichimoto et.al (PASJ, 48, 545, 1996) on the solar corona in conjunction with the total solar eclipse of 1994 to evaluate the temperature profiles of the solar corona. We have modified Cram's theory to incorporate the role of the solar wind in the formation of the K-corona and have identified both temperature and speed sensitive intensity ratios. We built MACS (Multi Aperture Coronal Spectrometer); a fiber optic based spectrograph to study the total solar eclipse of June 2001 in Lusaka, Zambia. In this instrument one end of the five fiber-optic tips at the focal plane of the telescope were positioned to see different latitudes at the same radii on the solar corona. The other ends of the fibers were vertically aligned and placed at the primary focus of the collimating lens of the spectrograph. We have succeeded in isolating the K-corona from the spectral observations made through two different fibers in MACS to match the theoretical K-coronal profiles for different temperatures and wind speeds. Results were obtained at two locations in the solar corona, one within a helmet streamer at the east limb and the second in a streamer cluster in the southwest. Both points were at an altitude of about 0.1-0.2 RSun above the solar limb. The east limb location at the edge of a helmet streamer and the southwest location yielded electron temperatures of 0.94 ± 0.01 MK and 1.28 ± 0.02 MK and bulk flow speeds of 124.0 ± 48.0 km/sec and 149.0 ± 59.0 km/sec, respectively. This mechanism provides for simultaneous measurement of both the temperature and wind speed in the field of view of an exposed fiber to the corona. We will also present the details of this experiment. Title: RHESSI and non-thermal solar physics in the IHY Authors: Hudson, H.; Davila, J.; Dennis, B.; Emslie, G.; Lin, R.; Ryan, J.; Share, G. Bibcode: 2003EAEJA.....7939H Altcode: The signatures of non-thermal activity on the Sun - X-rays, gamma-rays, and high-energy particles - present us with the closest possible view of the essential physics underlying solar activity and its heliospheric consequences. During the International Heliophysical Year (2007) we will have a rich harvest of measurements from current sunspot maximum from an unprecedented array of observations from space. This poster will present the most recent observations from the newest spacecraft, RHESSI (the Reuven Ramaty High-Energy Solar Spectroscopic Imager) in the context of the IHY and possible future programs. The RHESSI data discussed emphasize the gamma-ray line flare of July 23, 2002 as well as discoveries made in the April 21, 2002 and other events. Title: COR1 inner coronagraph for STEREO-SECCHI Authors: Thompson, William T.; Davila, Joseph M.; Fisher, Richard R.; Orwig, Larry E.; Mentzell, John E.; Hetherington, Samuel E.; Derro, Rebecca J.; Federline, Robert E.; Clark, David C.; Chen, Philip T. C.; Tveekrem, June L.; Martino, Anthony J.; Novello, Joseph; Wesenberg, Richard P.; StCyr, Orville C.; Reginald, Nelson L.; Howard, Russell A.; Mehalick, Kimberly I.; Hersh, Michael J.; Newman, Miles D.; Thomas, Debbie L.; Card, Gregory L.; Elmore, David F. Bibcode: 2003SPIE.4853....1T Altcode: The Solar Terrestrial Relations Observatory (STEREO) is a pair of identical satellites that will orbit the Sun so as to drift ahead of and behind Earth respectively, to give a stereo view of the Sun. STEREO is currently scheduled for launch in November 2005. One of the instrument packages that will be flown on each of the STEREO spacecrafts is the Sun Earth Connection Coronal and Heliospheric Investigation (SECCHI), which consists of an extreme ultraviolet imager, two coronagraphs, and two side-viewing heliospheric imagers to observe solar coronal mass ejections all the way from the Sun to Earth. We report here on the inner coronagraph, labeled COR1. COR1 is a classic Lyot internally occulting refractive coronagraph, adapted for the first time to be used in space. The field of view is from 1.3 to 4 solar radii. A linear polarizer is used to suppress scattered light, and to extract the polarized brightness signal from the solar corona. The optical scattering performance of the coronagraph was first modeled using both the ASAP and APART numerical modeling codes, and then tested at the Vacuum Tunnel Facility at the National Center for Atmospheric Research in Boulder, Colorado. In this report, we will focus on the COR1 optical design, the predicted optical performance, and the observed performance in the lab. We will also discuss the mechanical and thermal design, and the cleanliness requirements needed to achieve the optical performance. Title: Advanced spectroscopic and coronographic explorer: science payload design concept Authors: Gardner, Larry D.; Kohl, John L.; Daigneau, Peter S.; Smith, Peter L.; Strachan, Leonard, Jr.; Howard, Russell A.; Socker, Dennis G.; Davila, Joseph M.; Noci, Giancarlo C.; Romoli, Marco; Fineschi, Silvano Bibcode: 2003SPIE.4843....1G Altcode: The Advanced Spectroscopic and Coronagraphic Explorer (ASCE) was proposed in 2001 to NASA's Medium-Class Explorer (MIDEX) program by the Smithsonian Astrophysical Observatory in collaboration with the Naval Research Laboratory, Goddard Space Flight Center and the Italian Space Agency. It is one of four missions selected for Phase A study in 2002. ASCE is composed of three instrument units: an Advanced Ultraviolet Coronagraph Spectrometer (AUVCS), an Advanced Large Aperture visible light Spectroscopic Coronagraph (ALASCO), and an Advanced Solar Disk Spectrometer (ASDS). ASCE makes use of a 13 m long boom that is extended on orbit and positions the external occulters of AUVCS and ALASCO nearly 15 m in front of their respective telescope mirrors. The optical design concepts for the instruments will be discussed. Title: Si IX Emission Lines in Spectra Obtained with the Solar euv Research Telescope and Spectrograph (Serts) Authors: Keenan, F. P.; Katsiyannis, A. C.; Aggarwal, K. M.; Mathioudakis, M.; Brosius, J. W.; Davila, J. M.; Thomas, R. J. Bibcode: 2003SoPh..212...65K Altcode: Theoretical electron-density-sensitive emission line ratios involving 2s22p2-2s2p3 transitions in Si ix between 223 and 350 Å are presented. A comparison of these with an extensive dataset of solar-active-region, quiet-Sun, subflare and off-limb observations, obtained during rocket flights by the Solar EUV Research Telescope and Spectrograph (SERTS), reveals generally very good agreement between theory and experiment. This provides support for the accuracy of the line-ratio diagnostics, and hence the atomic data on which they are based. In particular, the density-sensitive intensity ratio I(258.10 Å)/I(349.87 Å) offers an especially promising diagnostic for studies of coronal plasmas, as it involves two reasonably strong emission lines and varies by more than an order of magnitude over the useful density range of 109-1011 cm−3. The 2s22p2 1S0-2s2p3 1P1 transition at 259.77 Å is very marginally identified for the first time in the SERTS database, although it has previously been detected in solar flare observations. Title: Empirically Constrained Multidimensional MHD Model for the Solar Corona and Solar Wind Authors: Sittler, E. C.; Ofman, L.; Gibson, S.; Guthathakurta, M.; Skoug, R.; Fludra, A.; Davila, J.; Holzer, T. Bibcode: 2002AGUFMSH21A0502S Altcode: We are developing a time stationary self-consistent 2D MHD model of the solar corona and solar wind that explicitly solves the energy equation, using a semi-empirical 2D MHD model of the corona to provide an empirically determined effective heat flux qeff (i.e., the term effective means the possible presence of wave contributions) for the energy equation and effective pressure Peff for the momentum equation. Preliminary results indicated that in order to achieve high speed winds over the poles we not only needed to use qeff in the energy equation, but also needed to include the empirically determined effective pressure Peff as a constraint in the momentum equation, which means that momentum addition by waves above 2 RS are required to produce high speed winds. A solution which only included qeff showed high acceleration over the poles below 2 RS, but then drooped above that radial distance indicating we needed momentum addition above that height to get high speed flows over the poles. We will show new results which include the added constraint of Peff in the momentum equation. This method will allows us to estimate the momentum addition term due to waves as a function of height and latitude within the corona. The estimates of Peff and qeff come from the semi-empirical 2D MHD model of the solar corona by Sittler and Guhathakurta (1999, 2002) which is based on Mk-III, Skylab and Ulysses observations. For future model development we plan to use SOHO LASCO, CDS, EIT, UVCS, Spartan 201-05 and Ulysses data as constraints for our model calculations. The model by Sittler and Guhathakurta (1999, 2002) is not a self-consistent calculation. The calculations presented here are a continuing effort to provide a self-consistent calculation based on empirical constraints. Title: The Advanced Spectroscopic and Coronagraphic Explorer (ASCE) Mission Concept Study Authors: Kohl, J.; Howard, R.; Davila, J.; Noci, G.; Gardner, L.; Socker, D.; Romoli, M.; Strachan, L.; Floyd, L.; Cranmer, S.; Raymond, J.; van Ballegooijen, A. Bibcode: 2002AGUFMSH52A0463K Altcode: The ASCE Mission is currently in a Phase A feasibility study as a candidate for the upcoming MIDEX selection. The ASCE science payload provides next generation spectroscopic and polarimetric instrumentation aimed at identifying the physical processes governing solar wind generation and coronal mass ejections (CMEs). During the current phase, engineering design and analyses have demonstrated the feasibility of accomplishing the original mission objectives within the MIDEX mission constraints. The launch is planned for early 2007 and the operations and analyses are expected to continue for 5 years. ASCE data along with data analysis software and calibration data will be unrestricted and available to the scientific community via an automated web site. A Guest Investigator program is planned with an average of 15 grants running concurrently during 2008 to 2012. Grants would be awarded in response to proposals submitted during the first and subsequent years of the mission. Title: The International Heliophysical Year (IHY) Authors: Davila, J. M.; Harrison, R.; Poland, A.; Thompson, B.; Gopalswamy, N. Bibcode: 2002AGUFMSH21A0518D Altcode: In 1957 a program of international research, inspired by the International Polar Years of 1882-83 and 1932-33, was organized as the International Geophysical Year (IGY) to study global phenomena of the Earth and geospace. The IGY involved about 60,000 scientists from 66 nations, working at thousands of stations, from pole to pole to obtain simultaneous, global observations on Earth and in space. There had never been anything like it before. The fiftieth anniversary of the International Geophysical Year will occur in 2007. We propose to organize an international program of scientific collaboration for this time period called the International Heliophysical Year (IHY). Like it predecessors, the IHY will focus on fundamental global questions of Earth science. Title: SHARPI: Solar High Angular Resolution Photometric Imager Authors: Rabin, D.; Davila, J.; Content, D.; Keski-Kuha, R.; Michael, S. Bibcode: 2002AAS...200.5606R Altcode: 2002BAAS...34..735R Observing the lower solar atmosphere with enough linear resolution (< 100 km) to study individual magnetic flux tubes and other features on scales comparable to the photon mean free path remains a challenging and elusive goal. Space-borne instruments based on conventional heavy optics proved to be too expensive, and adaptive optics on the ground made slow progress for many years. Yet, the scientific case for high-resolution imaging and magnetography has only become more compelling over the last ten years. Today, ground-based adaptive optics is a promising approach for small fields of view at visible wavelengths. Space experiments will need to employ lightweight optics and low-cost platforms. The Sunrise balloon experiment is one example. We describe a concept for a sounding rocket experiment that will achieve 0.1-arcsecond imaging using a lightweight, ultraprecise 55-cm mirror in the far ultraviolet (160 nm continuum, Lyman alpha, and possibly C IV 155 nm). The f/1.2 parabolic primary mirror is entering the final stages of production. The mirror is a ULE honeycomb design with front and back face sheets. The front sheet will be figured to 6.3 nm rms with microroughness 1 nm or better. For the initial proof of concept, we describe a no-frills, high-cadence imager aboard a Black Brant sounding rocket. Development of lightweight UV/EUV optics at Goddard Space Flight Center has been supported by the GSFC Internal Research and Development program. Title: A New Diagnostic Technique for the Solar Corona Authors: Davila, J. M.; Nelson, R.; St. Cyr, O. C. Bibcode: 2002AAS...200.5607D Altcode: 2002BAAS...34..735D Over the last 30-40 years spectroscopic observation of the EUV line emission has proved invaluable as a diagnostic of the solar coronal plasma state. Line ratios have been used to determine electron density, electron temperature and ion flow velocity. In this paper, we present results obtained with a new measurement technique that uses spectroscopic observations of the white light corona to obtain the electron density, temperature, and flow velocity. A prototype instrument has been designed and built to obtain visible light spectra (3800-4300 A) with modest resolution. This instrument was used to obtain coronal observations during the June 2001 eclipse in Zambia. The data were corrected for sky and instrument transmission to derive the electron temperature and flow speed. Results from these measurements will be discussed. Title: Science Prospects for the STEREO Mission Authors: Davila, J.; St-Cyr, O. Bibcode: 2002cosp...34E.478D Altcode: 2002cosp.meetE.478D The solar magnetic field is constantly generated beneath the surface of the Sun by the solar dynamo. To balance this flux generation, there is constant dissipation of magnetic flux at and above the solar surface. The largest phenomenon associated with this dissipation is the Coronal Mass Ejection (CME). The Solar and Heliospheric Observatory (SOHO) has provided remarkable views of the corona and CMEs, and served to highlight how these large interplanetary disturbances can have terrestrial consequences. STEREO is the next logical step to study the physics of CME origin, propagation, and terrestrial effects. Two spacecraft with identical instrument complements will be launched on a single launch vehicle in November 2007. One spacecraft will drift ahead and the second behind the Earth at a separation rate of 22 degrees per year. Observation from these two vantage points will for the first time allow the observation of the threedimensional structure of CMEs and the coronal structures where they originate Each STEREO spacecraft carries a complement of 10 instruments, which include (for the first time) an extensive set of BOTH remote sensing and in-situ instruments. The remote sensing suite is capable of imaging CMEs from the solar surface out to beyond EarthSs orbit (1 AU), and in-situ instruments are able to measure distribution functions for electrons, protons, and ions over a broad energy range, from the normal thermal solar wind plasma to the most energetic solar particles. It is anticipated that these studies will ultimately lead to an increased understanding of the CME process and eventually to the ability to predict CME occurrence and thereby - SforecastS the condition of the near-Earth environment. Title: The International Heliophysical Year Concept Authors: Davila, J.; Harrison, R.; Poland, A.; St-Cyr, O.; Thompson, B. Bibcode: 2002cosp...34E.529D Altcode: 2002cosp.meetE.529D In 1957 a program of international research, inspired by the International Polar Years of 1882-83 and 1932-33, was organized as the International Geophysical Year (IGY) to study global phenomena of the Earth and geospace. The IGY involved about 60,000 scientists from 66 nations, working at thousands of stations, from pole to pole to obtain simultaneous, global observations on Earth and in space. There had never been anything like it before. The fiftieth anniversary of the International Geophysical Year will occur in 2007. We propose to organize an international program of scientific collaboration for this time period called the International Heliophysical Year (IHY). Like its predecessors, the IHY will focus on fundamental global questions of Earth science. Title: International Polar Year 2007: An Integrated Heliospheric and Oceanographic Program? Authors: Johnson, G.; Davila, J. Bibcode: 2002cosp...34E1194J Altcode: 2002cosp.meetE1194J An international symposium SPerspectives of Modern Polar ResearchT was convened - in Bad Durkeim, Germany 2001 to celebrated the 175the anniversary of the birth of Georg von Neumayer. At that symposium the Nermayer Declaration was adopted to commemorate the 125th anniversary of the IPY in 2007. SA 125th year IPY program be initiated using new and present technologies to determine: 1 . Causes and effects of climatic variability-air/sea/ice interactins, and 2. Lithosphere dynamicsUevolution and history of crust and sedimentary cover. The po lar regions would be the focus.T Polar oceanographic contributions to global climate change are still a matter of conjecture, and to a large extent so are the extraterrestrial contributions. The proposed IPY would focus on these issues. As part of the global heat engine, the polar regions hav a major role in the worldSs transfer of energy, and the ocean/stmosphere system is known to be both an indicator and a componenet of climate change. It is clear that acomplex suite of significant, interrelated, atmospheric, oceanic and terrestrial changes has occurred in the the polsar regions in recent decades. These events are affecting every part of the polar environment and are having repercussions on society. In a similar vein an International Heliophysical Year (IHY) has been proposed to obtain a coordinated set of observations to study at the largest scale the solar genergated events that affect life and climate on Earth as has been documented in the Holocene sedimentary recofd. A modeling capability is the ultimate goal so the physical process can be tracked throughout the entire Sun-Earth system. This program will require an integrated, holistic system approach encompassing a side range of disciplines with new and improved technologies for long term measurements on the seabed, in the water column and in space over all seasons. Coordination, collaboration and documentation of an interated science plan with international scientific organizations/scientists via joint workshops are the next steps. Title: New Observations of Oscillating Coronal Loops Authors: Reeves, K. K.; Shoer, J.; Deluca, E. E.; Winebarger, A. R.; Ofman, L.; Davila, J. M. Bibcode: 2001AGUFMSH11A0704R Altcode: One of the most promising discoveries of the TRACE mission is the first observations of transverse oscillations in coronal loops (Aschwanden et al 1999, Nakariakov et al 1999). Loops are set into motion from nearby flares, oscillate with a well defined frequency and decay on a time scale of 10 minutes. While the theoretical study of MHD waves in the corona has a long history, observational support has dramatically increased over the past 10 years as coronal instruments have improved. The transverse oscillations have been identified as standing kink modes for the 14-July-1998 observations cited above. In this paper we present clear evidence for a decaying global kink modes observed by TRACE on 15-Apr-2001. Six different loops have been observed to oscillate with a frequency in the range: 15-20 mHz (compared with 4 mHz for 14-July-1998) and a decay time in the range: 8-23 minutes (compared with 11 minutes for the earlier event). The implications for these results for coronal diagnostics and solar coronal seismology will be discussed. Title: EUNIS: a solar EUV normal-incidence spectrometer Authors: Thomas, Roger J.; Davila, Joseph M. Bibcode: 2001SPIE.4498..161T Altcode: GSFC is in the process of assembling a solar EUV Normal-Incidence Spectrometer called EUNIS, to be flown as a sounding rocket payload. This instrument builds on the many technical innovations pioneered by our highly successful SERTS experiment over its past ten flights. The new design has improved spatial and spectral resolutions, as well as 100 times greater sensitivity, permitting EUV spectroscopy with a temporal resolution near 1 second for the first time ever. To achieve such high time cadence, a novel Active-Pixel-Sensor detector is being developed as a key component of our design. The high sensitivity of EUNIS allows entirely new studies of transient coronal phenomena, such as the rapid loop dynamics seen by TRACE, and searches for non-thermal motions indicative of magnetic reconnection or wave heating. The increased sensitivity also permits useful EUV spectra at heights of 2-3 solar radii above the limb, where the transition between the static corona and the solar wind might occur. In addition, the new design features two independent optical systems, more than doubling the spectral bandwidth covered on each flight. Its 300-370A bandpass includes He II 304A and strong lines from Fe XI-XVI, extending the current SERTS range of 300-355A to further improve our ongoing series of calibration under-flights for SOHO/CDS and EIT. The second bandpass of 170-205A has a sequence of very strong Fe IX-XIII lines, and allows under-flight support for two more channels on SOHO/EIT, two channels on TRACE, one on Solar-B/EIS, and all four channels on the STEREO/EUVI instrument. First flight of the new EUNIS payload is presently scheduled for 2002 October. Title: The Advanced Spectroscopic and Coronagraphic Explorer Mission Authors: Kohl, J. L.; Howard, R.; Davila, J.; Noci, G.; Esser, R.; Ciaravella, A.; Cranmer, S.; Fineschi, S.; Gardner, L.; Raymond, J.; Romoli, M.; Smith, P.; Socker, D.; Strachan, L.; Van Ballegooijen, A. Bibcode: 2001AGUFMSH31B0711K Altcode: SOHO has provided profound insights into the physics of solar wind acceleration and coronal mass ejections. Although significant progress has been made, most of the dominant physical processes controlling these phenomena are still not identified. The Advanced Spectroscopic and Coronagraphic Explorer Mission provides next generation spectroscopic and polarimetric instrumentation aimed at identifying these processes. The launch is planned for March 2007 with mission operations and data analysis continuing for 5 years. The data will be unrestricted and available to the community. The envisioned program includes a Guest Investigator Program with an average of 15 grants to be awarded in response to proposals submitted during the first year of the mission. Information about the proposed scientific goals and instrumentation will be presented. Title: Three-Fluid 2.5-dimensional Magnetohydrodynamic Model of the Effective Temperature in Coronal Holes Authors: Ofman, L.; Davila, J. M. Bibcode: 2001ApJ...553..935O Altcode: Recent SOHO Ultraviolet Coronagraph Spectrometer (UVCS) observations show that protons and minor ions are hot (Tp>106 K, Ti>107 K) and anisotropic in coronal holes. A possible cause of the large perpendicular motions is unresolved Alfvénic fluctuations in the solar wind. Using the three-fluid 2.5-dimensional MHD model, we have shown that the unresolved Alfvénic fluctuations lead to apparent proton temperature and anisotropy consistent with UVCS observations. However, Alfvén waves with realistic amplitudes cannot reproduce the O5+ perpendicular temperature and anisotropy deduced from UVCS observations. This suggests that the minor ions are heated by a different mechanism than protons. Title: Spectroscopy of Coronal Electrons -- White-light Measurements Authors: Reginald, N.; Davila, J. M.; St. Cyr, O. C. Bibcode: 2001AGUSM..SH32B03R Altcode: We report on our continuing efforts to refine the technique described by Reginald and Davila (2000) where white-light spectroscopy is used to measure the solar wind velocity and electron temperature globally. This method is complementary to those that have been used to date (e.g., UV and EUV spectral measurements; visible line ratios; interplanetary radio scintillation, and semi-empirical modeling). This paper will concentrate on instrumentation issues, and modeling efforts relevant to the technique are reported elsewhere in this volume. Results from the 1999 total eclipse in Turkey will be shown, and preparations for the 2001 eclipse in Africa will be discussed. A second related technique using passband filters will also be deployed in 2001 for direct comparison to the spectroscopic method. A groundbased coronagraph is under development to extend this technique beyond eclipse opportunities. But the low stray light levels available on a spacebased platform, along with the heritage of coronagraphic techniques, should make this technique a strong candidate for future spaceflight opportunities. Title: Modeling the Spectrum of the K-corona with Embedded Streamers Authors: Reginald, N.; Davila, J. M. Bibcode: 2001AGUSM..SH41B23R Altcode: The white light emission from the corona is generated by the Thomson scattering of photospheric emission by electrons. Recently Reginald and Davila (Solar Phys, 2000) have developed models, assuming a radially symmetric coronal electron density, that suggest that spectral measurements of the K-coronal emission can be used to determine the electron temperature, and the radial outflow velocity of electrons in the low corona. These measurements could provide for continuous remote-sensing observation of the solar wind speed from a spacecraft located at say L1. Recently these models have been extended to include the effect of streamers. Streamers are modeled simply as localized density enhancements along the line of sight. During this paper, the results of these models will be discussed, and the effect on the measurement of electron temperature and velocity will be assesed. Experimental efforts to verify these model predictions will be discussed in a separate paper also presented at this meeting. Title: Multifluid and Hybrid Modeling of Waves in Coronal Holes: Implications for Heating Theories Authors: Ofman, L.; Davila, J. M. Bibcode: 2001AGUSM..SH22E01O Altcode: Recent SOHO Ultraviolet Coronagraph Spectrometer (UVCS) observations show that protons and minor ions are hot (Tp>106 K, Ti>107 K) and anisotropic in coronal holes. A possible cause of the large perpendicular motions is unresolved Alfvénic fluctuations in the solar wind. Using the three-fluid 2.5D MHD model we have shown that the unresolved Alfvénic fluctuations lead to apparent proton temperature and anisotropy consistent with UVCS observations. However, \Alfven waves with realistic amplitudes can not reproduce the O5+ perpendicular temperature and anisotropy deduced from UVCS observations. We use the hybrid model to investigate constrains on the anisotropy of the minor ions. Our results suggests that the minor ions are heated and accelerated by high-frequency waves ( ~103 Hz), while proton heating occurs by low frequency waves ( ~10-3 Hz). Title: EUNIS: Extreme-Ultraviolet Normal-Incidence Spectrometer Authors: Thomas, R. J.; Davila, J. M. Bibcode: 2001AGUSM..SP21B05T Altcode: GSFC is in the process of assembling an Extreme-Ultraviolet Normal-Incidence Spectrometer called EUNIS, to be flown as a sounding rocket payload. This instrument builds on the many technical innovations pioneered by our highly successful SERTS experiment, which has now flown a total of ten times, most recently last summer. The new design will have somewhat improved spatial and spectral resolutions, as well as two orders of magnitude greater sensitivity, permitting high signal/noise EUV spectroscopy with a temporal resolution near 1~second for the first time ever. In order to achieve such high time cadence, a novel detector system is being developed, based on Active-Pixel-Sensor electronics, a key component of our design. The high sensitivity of EUNIS will allow entirely new studies of transient coronal phenomena, such as the rapid loop dynamics seen by TRACE, and searches for non-thermal motions indicative of magnetic reconnection or wave heating. Another observing mode will be to raster a two dimensional region on the disk, giving data on much larger solar areas than could be covered with SERTS. The increased sensitivity will also permit useful EUV spectra at heights of 2--3~Rsun above the limb, where the transition between the static corona and the solar wind might occur. In addition, the new design features two independent optical systems, which more than double the spectral bandwidth covered on each flight. Its 300--370Å bandpass includes He~II 304Å and strong lines from Fe~XI--XVI, extending the current SERTS range of 300--355Å to further improve our ongoing series of calibration under-flights for SOHO/CDS and EIT. The second bandpass of 170--230Å has a sequence of very strong Fe~IX--XIV lines, and will allow under-flight support for two more channels on SOHO/EIT, two channels on TRACE, one on Solar-B/EIS, and all four channels on the STEREO/EUVI instrument. First flight of the new EUNIS payload is scheduled for 2002 October from White Sands Missile Range, New Mexico. This work is supported under NASA RTOP 344-17-38. Title: Huge Coronal Structure and Heating Constraints Determined from SERTS Observations Authors: Falconer, D. A.; Davila, J. M. Bibcode: 2001ApJ...547.1109F Altcode: Intensities of the extreme-ultraviolet (EUV) spectral lines were measured as a function of radius off the solar limb by two flights of the Goddard's Solar Extreme-Ultraviolet Rocket Telescope and Spectrograph (SERTS) for three quiet-Sun regions. Density scale heights were determined for the different spectral lines. Limits on the filling factor were determined. In the one case where an upper limit was determined it was much less than unity. Coronal heating above 1.15 solar radii is required for all three regions studied. For reasonable filling factors, local heating is needed. Title: Overview of the Solar Ultraviolet Magnetograph Investigation Authors: West, Edward A.; Porter, Jason G.; Davis, John M.; Gary, G. Allen; Rabin, Douglas M.; Thomas, Roger J.; Davila, Joseph M. Bibcode: 2000SPIE.4139..350W Altcode: Traditional magnetographs measure the solar magnetic field at the visible 'surface' of the Sun, the photosphere. The Solar Ultraviolet Magnetograph Investigation (SUMI) is a hardware development study for an instrument to measure the solar magnetic field higher in the atmosphere, in the upper chromosphere and in the transition region at the base of the corona. The magnetic pressure at these levels is much stronger than the gas pressure (in contrast to the situation at the photosphere), so the field controls the structure and dynamics of the atmosphere. Rapid changes in the magnetic structure of the atmosphere become possible at this height, with the release of energy. Measurements of the vector magnetic field in this region will significantly improve our understanding of the physical processes heating the Sun's upper atmosphere and driving transient phenomena such as flares and coronal mass ejections. The instrument will incorporate new technologies to achieve the polarization efficiencies required to measure the magnetic splitting of lines in the VUV an UV (CIV at 1550 angstrom and MgII at 2800 angstrom). We describe the scientific goals, the optical components that are being developed for a sounding rocket program, and the SUMI baseline design. Title: Analysis of a Solar Active Region Extreme-Ultraviolet Spectrum from SERTS-97 Authors: Brosius, Jeffrey W.; Thomas, Roger J.; Davila, Joseph M.; Landi, Enrico Bibcode: 2000ApJ...543.1016B Altcode: Goddard Space Flight Center's Solar EUV Research Telescope and Spectrograph was flown on 1997 November 18, carrying an intensified CCD detector and a multilayer-coated toroidal diffraction grating with enhanced sensitivity over that of a standard gold-coated grating throughout the instrument's 299-353 Å spectral bandpass. Spectra and spectroheliograms of NOAA Active Region 8108 (N21°, E18°) were obtained with a spectral resolution (instrumental FWHM) of 115 mÅ. Nearly 100 emission lines were observed in the spatially averaged active region spectrum. Spectra and spectroheliograms of quiet areas south of the region were also obtained. An end-to-end radiometric calibration of the rocket instrument was carried out at the Rutherford-Appleton Laboratory in the same facility that was used to calibrate the Coronal Diagnostic Spectrometer experiment on SOHO and using the same EUV light source. The accuracy of this calibration is confirmed by the excellent agreement between the measured and theoretical values of density- and temperature-insensitive line intensity ratios. Nine emission lines of Fe XV are identified in our spectrum; however, large differences between wavelengths in the CHIANTI database and some of the measured solar wavelengths, as well as inconsistencies of various theoretical intensity ratios, suggest a need for improvement in the Fe XV atomic physics parameters and/or the presence of unidentified blending lines. Density-sensitive line intensity ratios of Fe XI λλ308.55/352.67, Fe XII λλ338.27/352.11, Fe XIII λλ320.80/312.17, and Fe XV λλ321.78/327.03 yield logarithmic electron densities (in cm-3) of 9.92+/-0.28, 9.74+/-0.28, 9.52+/-0.30, and 9.62+/-0.26, respectively. Using the strongest emission line observed for each ionization stage of Fe from X through XVI and Ni XVIII, we find that all of the measured nonthermal line widths yield velocities consistent with 35 km s-1. The differential emission measure curve derived from the observed line intensities exhibits a relative minimum at logT~5.7, a broad maximum centered around logT~6.3, and a rapid decline for temperatures above logT~6.6. Title: The Solar Terrestrial Relations Observatory - Mission Overview Authors: Davila, J. M.; Rust, D. M.; Sharer, P. J. Bibcode: 2000SPD....31R0293D Altcode: 2000BAAS...32.1291D Starting in 2004, the two identical STEREO spacecraft will drift slowly off the Sun-Earth line, providing a series of differing perspectives on CMEs and other solar and heliospheric structures. At the end of the prime science (2-year) mission, the spacecraft will each be about 45 degrees from Earth, one leading Earth and one trailing. Each spacecraft will carry a cluster of telescopes, including coronagraphs, EUV imagers, and particle detectors. When the images are combined with solar magnetograms and other data from observatories on the ground or in low Earth orbit, both the buildup of magnetic energy and the lift off and trajectory of CMEs can be studied. Interpreting the STEREO data will pose a new challenge to the solar community. We discuss the STEREO mission design, instrument complement and the development of the trajectory design that, we believe, maximizes the scientific potential of the mission. Title: Space Weather Diamond: a four spacecraft monitoring system Authors: Cyr, O. C. S.; Mesarch, M. A.; Maldonado, H. M.; Folta, D. C.; Harper, A. D.; Davila, J. M.; Fisher, R. R. Bibcode: 2000JASTP..62.1251C Altcode: 2000JATP...62.1251C We report here preliminary results of a mission analysis for a space weather monitoring system that provides continuous transmission of solar wind conditions 0.10 A.U. upstream from Earth. The system is based on four platforms that are phased into eccentric heliocentric orbits but, from the perspective of a fixed Sun-Earth line, the spacecraft appear to orbit Earth. This system offers a /10× improvement in reporting solar wind plasma and magnetic field characteristics beyond similar platforms located at the Lagrangian /L-1 point. We describe launch and energy considerations, along with a preliminary analysis of communication requirements. The Space Weather Diamond offers significant potential for scientific insight into problems requiring coordinated observations from multiple vantage points by providing the ability to separate spatial from temporal variations. We discuss examples for payloads including both in situ and remote sensing instrumentation. Title: MACS for Global measurement of the Solar wind velocity and the Thermal electron temperature during the Total solar eclipse on 11 August 1999 Authors: Reginald, Nelson L.; Davila, Joseph M. Bibcode: 2000SoPh..195..111R Altcode: MACS for Multi-Aperture Coronal Spectrometer is a fiber-optic-based spectrograph designed and used to perform global measurement of the solar wind velocity and the thermal electron temperature of the solar corona during the total solar eclipse on 11 August 1999. The motivation for the construction of MACS was provided by the theory formulated by Cram (1976) for the formation of the K-coronal spectrum and a method for determining the radial profile of the thermal electron temperature of the solar corona. Based on this theory a subsequent application was carried out by Ichimoto et al. (1996) using a slit-based spectroscopic study during the total solar eclipse on 3 November 1994. We have modified Cram's theory to incorporate the role of the solar wind velocity in the formation of the K-corona and have identified wind and temperature sensitive intensity ratios. Instead of a slit-based spectrograph MACS consists of twenty fiber optic tips placed at the focal plane of the telescope and positioned to see different radii and latitudes of the solar corona. Another fiber is placed at the center of the frame and uses the lunar shadow for a measure of the background signal. The other ends of the fibers are vertically aligned and placed at the primary focus of the collimating lens of the spectrograph thus providing simultaneous spectra from all of the fibers. In this first paper (Paper I) we describe our instrument and the obtained coronal spectra. The final and complete results will be presented in Paper II (Reginald and Davila, 2000). Title: Three-dimensional MHD modeling of an impulsive excitation of a coronal loop motivated by TRACE observations Authors: Ofman, L.; Davila, J. M. Bibcode: 2000SPD....31.0604O Altcode: 2000BAAS...32..838O Recently, decaying transversal oscillations of bright coronal loops in the 171 Angstroms and 195 Angstroms emission lines were observed with the imaging telescope on-board the TRACE satellite. The loop oscillations were excited impulsively by a solar flare in the adjacent active region. Using 3D MHD model of the loop the period and the decay rate of the oscillations, together with the loop geometry, density, and temperature can be used to determine the average magnetic field of the loop, and the magnetic or viscous Reynolds number (R). Recently, Nakariakov et al. (1999) used the R1/5 heating time scaling to determine the range of the dissipation coefficients in the loop observed with TRACE. Using the linearized 3D MHD model we investigate the coupling of the decaying transverse mode and the internal Alfvén mode, and examine the relation between the decay time of the transverse oscillations and the heating time of the loop for a range of Reynolds numbers, and wavenumbers. We use the nonlinear 3D MHD model with more realistic loop geometry, boundary conditions, and mode coupling to study the relaxation of the impulsively excited coronal loop oscillation. We find that when the Reynolds number is large (R=104) the nonlinear effects become important at the resonant dissipation layer, and the heating time decreases compared to the linear case. We plan to expand the nonlinear 3D model to include the effects of gravity, and loop curvature to better model the loop oscillations observed by TRACE. LO would like to acknowledge support by the NASA SR&T, and the HPCC programs. Title: Re-Calibration of SOHO by SERTS-99 Authors: Thomas, R. J.; Davila, J. M.; Thompson, W. T.; Kent, B. J.; Hollandt, J. Bibcode: 2000SPD....31.0215T Altcode: 2000BAAS...32..813T GSFC's Solar EUV Research Telescope and Spectrograph (SERTS) is a rocket instrument that obtains imaged high-resolution spectra of individual solar features to study the Sun's corona and upper transition region. As with SERTS-97, an additional goal of the SERTS-99 flight on 1999 June 24 was to provide radiometric and wavelength calibrations for several experiments on the SOHO satellite mission. For that purpose, a second end-to-end radiometric calibration of SERTS was carried out last fall at RAL in the same facility used to characterize the SOHO/CDS experiment, using the same EUV light source specially re-calibrated by PTB against the synchrotron radiation standard of the BESSY-I electron storage ring. Measurements at a single SERTS aperture position were made to determine the instrument's absolute response within 25% at 12 wavelengths covering its bandpass of 300 -- 365 Angstroms. These were converted into full-aperture values through relative response measurements over a complete range of radial aperture positions. Also, post-flight wavelength calibrations were done at GSFC using well known laboratory lines of He II and Ne II. SERTS-99 again carried an EUV solar flux monitor kindly provided by USC; its readings were used to validate our calculations of atmospheric EUV transmission over the rocket's trajectory, and to provide an updated calibration for one of the SOHO/CELIAS channels. During the flight, SERTS-99 and CDS observed the same solar locations, as demonstrated by subsequent data co-registration with simultaneous SOHO/EIT images, allowing the SERTS calibrations to be directly applied to both CDS and EIT. Since it clearly resolves the strong Si XI and He II lines blended in EIT's 304 Angstroms channel, SERTS gives information on the spectral composition of those images as well. Examples of various cross-calibrations will be compared with results from November 1997, prior to SOHO's temporary loss of pointing control. This work is supported under NASA RTOP 344-17-38. Title: The Role of Velocity Redistribution in Enhancing the Intensity of the HE II 304 Å Line in the Quiet-Sun Spectrum Authors: Andretta, Vincenzo; Jordan, Stuart D.; Brosius, Jeffrey W.; Davila, Joseph M.; Thomas, Roger J.; Behring, William E.; Thompson, William T.; Garcia, Adriana Bibcode: 2000ApJ...535..438A Altcode: We present observational evidence of the effect of small-scale (``microturbulent'') velocities in enhancing the intensity of the He II λ304 line with respect to other transition region emission lines, a process we call ``velocity redistribution,''. We first show results from the 1991 and 1993 flights of SERTS (Solar EUV Rocket Telescope and Spectrograph). The spectral resolution of the SERTS instrument was sufficient to infer that, at the spatial resolution of 5", the line profile is nearly Gaussian both in the quiet Sun and in active regions. We were then able to determine, for the quiet Sun, a lower limit for the amplitude of nonthermal motions in the region of formation of the 304 Å line of the order of 10 km s-1. We estimated that, in the presence of the steep temperature gradients of the solar transition region (TR), velocities of this magnitude can significantly enhance the intensity of that line, thus at least helping to bridge the gap between calculated and observed values. We also estimated the functional dependence of such an enhancement on the relevant parameters (nonthermal velocities, temperature gradient, and pressure). We then present results from a coordinated campaign, using SOHO/CDS and Hα spectroheliograms from Coimbra Observatory, aimed at determining the relationship between regions of enhanced helium emission and chromospheric velocity fields and transition region emission in the quiescent atmosphere. Using these data, we examined the behavior of the He II λ304 line in the quiet-Sun supergranular network and compared it with other TR lines, in particular with O III λ600. We also examined the association of 304 Å emission with the so-called coarse dark mottle, chromospheric structures seen in Hα red-wing images and associated with spicules. We found that all these observations are consistent with the velocity redistribution picture. Title: Three-dimensional MHD modeling of an impulsive excitation of a coronal loop motivated by TRACE observations. Authors: Ofman, L.; Davila, J. M. Bibcode: 2000BAAS...32..837O Altcode: No abstract at ADS Title: Coronal seismology: using oscillations to understand coronal structure. Authors: Davila, J. M. Bibcode: 2000BAAS...32R.837D Altcode: No abstract at ADS Title: MACS for global measurements of the thermal electron temperature and the solar wind velocity in the solar corona during the total solar eclipse of 11 August 1999 Authors: Reginald, N. L.; Davila, J. M. Bibcode: 2000SPD....31.1605R Altcode: 2000BAAS...32..849R The determination of the radial and latitudinal temperature and wind profiles of the solar corona is of immense importance in understanding the coronal heating mechanism and the dynamics of the coronal features. Cram (1976) provides the theory for the formation of the K-coronal spectrum and a method for determining the radial profile of the coronal temperature. A slit-based spectroscopic study was performed by Ichimoto et.al (1996) on the solar corona in conjunction with the total solar eclipse of 1994 to evaluate the temperature profiles of the solar corona. We have modified Cram's theory to incorporate the role of the solar wind in the formation of the K-corona and have identified both temperature and wind sensitive intensity ratios. We built MACS (Multi Aperture Coronal Spectrometer); a fiber optic based spectrograph to study the total solar eclipse of August 1999 in Elazig, Turkey. In this instrument one end of the twenty fiber optic tips at the focal plane of the telescope were positioned to see different radii and latitudes of the solar corona. The other ends of the fibers were vertically aligned and placed at the primary focus of the collimating lens of the spectrograph. By isolating the K-coronal spectrum and calculating the temperature and the wind sensitive intensity ratios we have simultaneously measured both the thermal electron temperatures and the solar wind velocities at some discrete locations on the solar corona. Title: Analysis of an Active Region EUV Spectrum from SERTS-97 Authors: Brosius, J. W.; Thomas, R. J.; Davila, J. M.; Landi, E. Bibcode: 2000SPD....31.0214B Altcode: 2000BAAS...32..813B Goddard Space Flight Center's Solar EUV Research Telescope and Spectrograph (SERTS) was flown on 1997 November 18, carrying a CCD-intensified detector and a multilayer-coated toroidal diffraction grating that enhanced the sensitivity over that of a standard gold-coated grating throughout the instrument's first-order waveband (299 -- 353 Angstroms). Spectra and spectroheliograms of NOAA active region 8108 (N21 E18) were obtained with a spectral resolution (instrumental FWHM) ~ 118 m Angstroms. Spectra and spectroheliograms of quiet areas southeast of the active region were also obtained. An end-to-end radiometric calibration of the rocket instrument was carried out at Rutherford-Appleton Laboratory in the same facility used to calibrate the Coronal Diagnostic Spectrometer (CDS) on the Solar and Heliospheric Observatory (SOHO) satellite, using the same EUV light source. The accuracy of this calibration is confirmed by the excellent agreement between measured and theoretical values of density- and temperature-insensitive line intensity ratios among some of the nearly 100 spectral lines observed in the spatially averaged active region spectrum. We present the spectrum itself, and discuss measurements of the plasma density, non-thermal mass motions, relative wavelength shifts, and the differential emission measure. This work is supported by NASA through RTOP grants and contract NAS5-99145. Title: Coronal Seismology: Using Oscillations to Understand Coronal Structure Authors: Davila, J. M. Bibcode: 2000SPD....31.0602D Altcode: 2000BAAS...32Q.838D Recent high resolution observations from TRACE have demonstrated that oscillations in the corona can be observed from space. In this paper we consider the following question. What is the nature of these motions, and how can they be used to understand something about the corona? We briefly review some of the observational results, and discuss the interpretation of these results within the framework of MHD wave propagation and damping in coronal loops, open flux tubes, and loops with cusp structures. The prospect for future improvements in the theory and observations will be discussed. Title: New Diagnostics of Coronal Heating and Solar Wind Acceleration Processes Achievable With The Advanced Solar Coronal Explorer (ASCE) Authors: Cranmer, S. R.; Kohl, J. L.; Gardner, L. D.; Raymond, J. C.; Strachan, L.; Smith, P. L.; Howard, R. A.; Davila, J. M.; Fisher, R. R.; Noci, G.; Tondello, G.; Socker, D. G.; Moses, D. Bibcode: 2000SPD....31.0297C Altcode: 2000BAAS...32..828C The Advanced Solar Coronal Explorer (ASCE) is a proposed NASA Medium-class Explorer (MIDEX) mission that underwent a detailed Concept Study in 1999. The science payload includes large aperture EUV and visible light coronagraphs. ASCE's unprecedented spectral range, spatial resolution, and sensitivity (30 to 100 times the EUV sensitivity of UVCS/SOHO) provide measurements needed to investigate the role of high-frequency and low-frequency waves in heating and accelerating the fast and slow speed solar wind. This presentation will outline the advanced capabilities of ASCE for obtaining detailed empirical descriptions of solar wind acceleration regions, specifying coronal temperatures, flow speeds, densities, and elemental abundances. Velocity distributions for electrons and more than 10 to 20 ion species with mass-to-charge ratios from 4 to 1 (including singly ionized helium) can be measured by ASCE in coronal holes and streamers. This information is sufficient to derive the wavenumber power spectrum of magnetic fluctuations that affect the primary electron/proton plasma. The main goal is to identify the physical processes responsible for heating and acceleration of the primary particles and minor ions in the fast and slow speed solar wind. Title: SUMI: The Solar Ultraviolet Magnetograph Authors: Davis, J. M.; Porter, J. G.; Gary, G. A.; West, E. A.; Rabin, D. M.; Thomas, R. J.; Davila, J. M. Bibcode: 2000SPD....31.0299D Altcode: 2000BAAS...32..828D A major focus of solar physics is the measurement of the temporal and spatial variability of solar magnetic fields from the photosphere into the lower corona, together with the study of how their behavior produces the dynamic phenomena in this region such as flares and CMEs. Considerable success has been achieved in the characterization of the full vector field in the photosphere, where β , the ratio of the gas pressure to the magnetic pressure, is gtrsim1. At higher levels in the atmosphere where β <<1, the magnetic field (through the Lorentz force) controls the structure and dynamics of the solar atmosphere, and rapid changes in structure with release of energy become possible. However, observations of the field at these higher levels have proven to be difficult, placing a serious limitation on our understanding of the physical processes occurring there. This poster will discuss the Solar Ultraviolet Magnetograph Investigation (SUMI), a hardware development study for an instrument capable of measuring the polarization in ultraviolet lines of C IV and Mg II formed in the transition region and upper chromosphere. We are currently developing optical technologies necessary to build an instrument that will achieve a major advance in performance over that of earlier attempts (e.g., SMM/UVSP). Initially configured as a sounding rocket payload, such a UV magnetograph would allow us to make exploratory measurements extending the observation of solar magnetic fields into new and dynamic regimes. This work is supported by NASA through the SEC Program in Solar Physics and the program for Technology Development for Explorer Missions and Sofia. Title: Mission to Provide First Stereo Views of Solar Eruptions Authors: Guhathakurta, M.; Davila, J. M. Bibcode: 2000SPD....31.1603G Altcode: 2000BAAS...32..849G STEREO mission will for the first time unveil the Sun in three dimensions. Its objective is to address the origin, evolution and interplanetary consequences of one the most massive disturbances in our solar system called the coronal mass ejection (CME). This will be achieved by sending two identically instrumented spacecraft, both at 1 AU orbit around the Sun, but one flying well ahead of the Earth and one behind. The instrument suite for STEREO will characterize the CME plasma all the way from the solar surface to the orbit of the Earth. These instruments will measure physical characteristics of CME's with remote sensing and local sensing instruments, allowing scientists to determine solar origins of CME's, their propagation into the interplanetary medium and ultimately their consequences on Earth's magnetic field. By viewing CME's from two different vantage points, STEREO will be able to pinpoint their speed and distance from Earth, and thus more accurately time the arrival of the plasma cloud. The planned 2004 launch date will enable STEREO to make observations during the simpler, declining phase of the current activity cycle, which is expected to reach solar maximum around the year 2000. The STEREO mission is a multilateral international collaboration involving participants from France, Germany, the United States, and United Kingdom. STEREO is the third mission within NASA's Solar-Terrestrial Probe (STP) Program, under the Agency's Sun-Earth Connections Theme. Title: SERTS-97 Measurements Of Relative Wavelength Shifts In Coronal Emission Lines Across A Solar Active Region Authors: Brosius, J. W.; Thomas, R. J.; Davila, J. M.; Thompson, W. T. Bibcode: 2000SoPh..193..117B Altcode: We used slit spectra from the 18 November 1997 flight of Goddard Space Flight Center's Solar EUV Rocket Telescope and Spectrograph (SERTS-97) to measure relative wavelength shifts of coronal emission lines as a function of position across NOAA active region 8108. The shifts are measured relative to reference wavelengths derived from spectra of the region's nearby quiet surroundings (not necessarily at rest) because laboratory rest wavelengths for the coronal EUV lines have not been measured to sufficient accuracy for this work. An additional benefit to this approach is that any systematic uncertainties in the wavelength measurements are eliminated from the relative shifts by subtraction. We find statistically significant wavelength shifts between the spatially resolved active region slit spectra and the reference spectrum. For He ii 303.78 Å the maximum measured relative red shift corresponds to a Doppler velocity ∼+13 km s−1, and the maximum relative blue shift corresponds to a Doppler velocity ∼−3 km s−1. For Si x 347.40 Å, Si xi 303.32 Å, Fe xiv 334.17 Å, and Fe xvi 335.40 Å the corresponding maximum relative Doppler velocities are ∼+19 and ∼−14, ∼+23 and ∼−7, ∼+10 and ∼−10, and ∼+13 and ∼−5 km s−1, respectively. The active region appears to be divided into two different flow areas; hot coronal lines are predominantly red-shifted in the northern half and either blue-shifted or nearly un-shifted in the southern half. This may be evidence that material flows up from the southern part of the region, and down into the northern part. Qualitatively similar relative wavelength shifts and flow patterns are obtained with SOHO/CDS spectra. Title: Winds from Luminous Late-Type Stars. I. The Effects of Nonlinear Alfvén Waves Authors: Airapetian, V. S.; Ofman, L.; Robinson, R. D.; Carpenter, K.; Davila, J. Bibcode: 2000ApJ...528..965A Altcode: We present the results of magnetohydrodynamic (MHD) modeling of winds from luminous late-type stars using a 2.5-dimensional, nonlinear MHD computer code. We assume that the wind is generated within an initially hydrostatic atmosphere and is driven by torsional Alfvén waves generated at the stellar surface. Two cases of atmospheric topology are considered: case I has longitudinally uniform density distribution and isotropic radial magnetic field over the stellar surface, and case II has an isotropic, radial magnetic field with a transverse density gradient, which we refer to as an ``atmospheric hole.'' We use the same set of boundary conditions for both models.The calculations are designed to model a cool luminous star, for which we assume an initial hydrostatic pressure scale height of 0.072 R*, an Alfvén wave speed of 92 km s-1 at the surface, and a wave period of 76 days, which roughly corresponds with the convective turnover time. For case I the calculations produce a wind with terminal velocity of ~22 km s-1 and a mass loss rate comparable to the expected value of 10-6 Msolar yr-1. For case II we predict a two-component wind: a fast (25 km s-1) and relatively dense wind outside of the atmospheric hole and a slow (15 km s-1), rarefied wind inside of the hole. Title: SERTS-95 Measurements of Wavelength Shifts in Coronal Emission Lines Across a Solar Active Region Authors: Brosius, Jeffrey W.; Thomas, Roger J.; Davila, Joseph M. Bibcode: 1999ApJ...526..494B Altcode: We used slit spectra from the 1995 flight of Goddard Space Flight Center's Solar EUV Rocket Telescope and Spectrograph (SERTS-95) to measure wavelength shifts of coronal emission lines in the core of NOAA active region 7870 relative to its immediate surroundings (its ``edge''). This method circumvents the unavailability of reliable laboratory rest wavelengths for the observed lines by using wavelengths from the edge spectrum as references. We derived the SERTS-95 wavelength calibration from measurements of a post-flight laboratory spectrum containing 28 He II and Ne II EUV standard wavelengths known to high accuracy. Wavelength measurements for lines of He I, Ne III, and additional lines of Ne II in the laboratory calibration spectrum provide more accurate values than were previously available, enabling these lines also to serve as future calibration standards. Six solar lines were chosen for this study, namely, He II at 303.78 Å, Fe XII at 193.51 Å, Fe XIII at 202.05 Å, Fe XIV at 211.33 Å, Fe XV at 284.15 Å, and Fe XVI at 335.41 Å. Because these lines are free from known blends in the SERTS-95 spectra and are either intrinsically strong or near the SERTS-95 peak sensitivity, they are our most reliable lines for measuring relative wavelength shifts in the spatially resolved active-region core spectra. The iron ions are the hottest ions ever used for this type of analysis. All six lines reveal statistically significant spatial variations in their measured relative wavelength shifts in the active-region core, including mixtures of blueshifts and redshifts (each with maximum values corresponding to relative Doppler velocities ~15 km s-1), indicating a dynamic, turbulent corona. For each of these lines we calculated weighted-average relative Doppler velocities from the wavelength shifts in the spatially resolved core spectra by weighting the shifts in the individual spatial pixels with their respective measurement uncertainties. This yields velocities of 3.3+/-1.1 km s-1 for He II, 5.2+/-1.6 km s-1 for Fe XII, 0.7+/-1.5 km s-1 for Fe XIII, -2.1+/-1.4 km s-1 for Fe XIV, 1.0+/-1.1 km s-1 for Fe XV, and -1.1+/-0.8 km s-1 for Fe XVI. We also calculated intensity-weighted relative Doppler velocities from the wavelength shifts in the spatially averaged core spectrum, obtaining corresponding values of 5.8+/-0.6 km s-1, 5.7+/-0.9 km s-1, 0.4+/-0.7 km s-1, -2.1+/-1.0 km s-1, 0.8+/-0.8 km s-1, and -1.1+/-0.5 km s-1. Combining the above six lines with several additional ones that are strong enough in both the edge and average core spectra to provide reliable centroid measurements, we find statistically significant net relative redshifts for lines of He II, Fe X, Fe XI, and Fe XII; lines of Fe XIII and Fe XV show no significant shift while lines of Si XI, Fe XIV, and Fe XVI show a small net relative blueshift. Where multiple lines are available for a given ion, the directions (red or blue) and magnitudes (except for Fe XI) of the relative shifts are mutually consistent. The net relative blueshift observed in the hottest active-region coronal lines in our sample, combined with the net relative redshift observed in the cooler active-region coronal lines, suggests a net upflow of heated material cospatially and cotemporally with a net downflow of cooler material. Title: Concept Study Report: Extreme-Ultraviolet Imaging Spectrometer Solar-B Authors: Doschek, George A.; Brown, Charles M.; Davila, Joseph M.; Dere, Kenneth P.; Korendyke, Clarence M.; Mariska, John T.; Seely, John F. Bibcode: 1999STIN...0011153D Altcode: We propose a next generation Extreme-ultraviolet Imaging Spectrometer (EIS) that for the first time combines high spectral, spatial, and temporal resolution in a single solar spectroscopic instrument. The instrument consists of a multilayer-coated off-axis telescope mirror and a multilayer-coated grating spectrometer. The telescope mirror forms solar images on the spectrometer entrance slit assembly. The spectrometer forms stigmatic spectra of the solar region located at the slit. This region is selected by the articulated telescope mirror. Monochromatic images are obtained either by rastering the solar region across a narrow entrance slit, or by using a very wide slit (called a slot) in place of the slit. Monochromatic images of the region centered on the slot are obtained in a single exposure. Half of each optic is coated to maximize reflectance at 195 Angstroms; the other half to maximize reflectance at 270 Angstroms. The two Extreme Ultraviolet (EUV) wavelength bands have been selected to maximize spectral and dynamical and plasma diagnostic capabilities. Spectral lines are observed that are formed over a temperature range from about 0.1 MK to about 20 MK. The main EIS instrument characteristics are: wavelength bands - 180 to 204 Angstroms; 250 to 290 Angstroms; spectral resolution - 0.0223 Angstroms/pixel (34.3km/s at 195 Angstroms and 23.6 km/s at 284 Angstroms); slit dimensions - 4 slits, two currently specified dimensions are 1" x 1024" and 50" x 1024" (the slot); largest spatial field of view in a single exposure - 50" x 1024"; highest time resolution for active region velocity studies - 4.4 s. Title: The Role of Velocity Redistribution in Enhancing the Intensity of the He II 304 A Line in the Quiet Sun Spectrum Authors: Andretta, Vincenzo; Jordan, Stuart D.; Brosius, Jeffrey W.; Davila, Joseph M.; Thomas, Roger J.; Behring, William E.; Thompson, William T.; Garcia, Adriana Bibcode: 1999STIN...9909151A Altcode: We present observational evidence of the effect of small scale ("microturbulent") velocities in enhancing the intensity of the He II lambda304 line with respect to other transition region emission lines, a process we call "velocity redistribution". We first show results from the 1991 and 1993 flights of SERTS (Solar EUV Rocket Telescope and Spectrograph). The spectral resolution of the SERTS instrument was sufficient to infer that, at the spatial resolution of 5", the line profile is nearly gaussian both in the quiet Sun and in active regions. We were then able to determine, for the quiet Sun, a lower limit for the amplitude of non-thermal motions in the region of formation of the 304 A line of the order of 10 km/s. We estimated that, in the presence of the steep temperature gradients of the solar Transition Region (TR), velocities of this magnitude can significantly enhance the intensity of that line, thus at least helping to bridge the gap between calculated and observed values. We also estimated the functional dependence of such an enhancement on the relevant parameters (non-thermal velocities, temperature gradient, and pressure). We then present results from a coordinated campaign, using SOHO/CDS and H-alpha spectroheliograms from Coimbra Observatory, aimed at determining the relationship between regions of enhanced helium emission and chromospheric velocity fields and transition region emission in the quiescent atmosphere. Using these data, we examined the behavior of the He II lambda304 line in the quiet Sun supergranular network and compared it with other TR lines, in particular with O III lambda600. We also examined the association of 304 A emission with the so-called "coarse dark mottle", chromospheric structures seen in H-alpha red wing images and associated with spicules. We found that all these observations are consistent with the velocity redistribution picture. Title: Spectroscopic study of the solar eclipse of August 1999 to understand the radial and latitudinal profiles of wind and temperature Authors: Reginald, N. L.; Davila, J. M. Bibcode: 1999AAS...19410802R Altcode: The determination of the radial temperature and the wind profiles of the solar corona is of immense importance in understanding the coronal heating mechanism and the dynamics of the coronal features. Cram (1976) provides the theory for the formation of the K-coronal spectrum and a method for determining the radial profile of the coronal temperature. A slit-based spectroscopic study has been performed by Ichimoto et.al (1996) on the solar corona in conjunction with a solar eclipse to evaluate the radial temeperature profiles of the solar corona. We have modified Cram's theory to incorporate the role of the solar wind in the formation of the K-corona. We are building a fiber optic based spectrograph to study the solar eclipse of August 1999. In this instrument one end of the twenty-five fiber tips at the focal plane of the telescope are positioned to see different radii and latitudes of the solar corona. The other ends of the fibers are vertically aligned and placed at the primary focus of the collimating lens of the spectrograph. By calculating the intensity ratios at wind and temperature sensitive wavelengths we believe that both the temperature and wind profiles could be determined at different radii and latitudes. Title: TRACE observation of damped coronal loop oscillations: Implications for coronal heating Authors: Nakariakov, V. M.; Ofman, L.; Deluca, E. E.; Roberts, B.; Davila, J. M. Bibcode: 1999Sci...285..862N Altcode: The imaging telescope on board the Transition Region and Coronal Explorer (TRACE) spacecraft observed the decaying transversal oscillations of a long [(130 ± 6) × 106 meters], thin [diameter (2.0 ± 0.36) × 106 meters], bright coronal loop in the 171 angstrom FeIX emission line. The oscillations were excited by a solar flare in the adjacent active region. The decay time of the oscillations is 14.5 ± 2.7 minutes for an oscillation with a frequency 3.90 ± 0.13 millihertz. The coronal dissipation coefficient is estimated to be eight to nine orders of magnitude larger than the theoretically predicted classical value. The larger dissipation coefficient may solve existing difficulties with wave heating and reconnection theories. Title: Two-fluid 2.5D MHD model of the fast solar wind and the effective proton temperature Authors: Ofman, L.; Davila, J. M. Bibcode: 1999AIPC..471..405O Altcode: 1999sowi.conf..405O Recent SOHO/UVCS observations indicate that the perpendicular proton and ion temperatures are much larger than electron temperatures (Kohl et al. 1997). In the present study we simulate numerically the solar wind flow in a coronal hole with the two-fluid approach. For simplicity, we neglect electron inertia. We investigate the effects of electron and proton temperatures on the solar wind acceleration by nonlinear waves. In the model the nonlinear waves are generated by Alfvén waves with frequencies in the 10-3 Hz range, driven at the base of the coronal hole. The resulting electron and proton flow profile exhibits density and velocity fluctuations. The fluctuations may steepen into shocks as they propagate away from the sun. We construct the proton velocity distribution and a synthetic Ly-α line profile by including the combined effects of temperature and velocity fluctuations in the model, and compare them to the UVCS observations. Title: The SERTS-97 Cross-Calibration of CDS & EIT on SOHO Authors: Thomas, R. J.; Davila, J. M.; Thompson, W. T.; Kent, B. J.; Hollandt, J. Bibcode: 1999AAS...194.1606T Altcode: 1999BAAS...31Q.850T GSFC's Solar EUV Rocket Telescope and Spectrograph (SERTS) obtains imaged high-resolution spectra of individual solar features, giving information about the Sun's corona and upper transition region. Its flight on 1997 November 18 had the additional goal of providing radiometric and wavelength calibrations for several experiments on the Solar and Heliospheric Observatory (SOHO) satellite mission. For that purpose, an end-to-end radiometric calibration of the rocket instrument was carried out at RAL in the same facility used to characterize the CDS experiment on SOHO, and using the same EUV light source specially re-calibrated by PTB against the synchrotron radiation of the electron storage ring BESSY, which is a primary EUV radiometric standard. Scans of the SERTS aperture over a range of pitch and yaw angles were made to determine the instrument's absolute spectral sensitivity to <= 25% at 12 wavelengths covering its range of 300 -- 365 Angstroms. Also, pre- and post-flight wavelength calibrations were done at GSFC using well known lines of He II and Ne II within the SERTS bandpass. For the first time, SERTS-97 carried an EUV solar flux monitor kindly provided by USC; its readings were used to validate our calculations of atmospheric EUV transmission over the rocket's trajectory. During the flight, SERTS-97 and CDS observed the same solar locations, as demonstrated by subsequent data co-registration with EIT images, allowing the SERTS calibrations to be directly applied to both CDS and EIT. Since SERTS clearly resolves the strong Si XI and He II lines blended in EIT's 304 Angstroms channel, SERTS measurements give information on the spectral composition of these images as well. Examples of the various cross-calibrations will be shown. This work has been supported through RTOP grants for the SERTS and SOHO programs from the Solar Physics Office of NASA's Space Physics Division. Title: SERTS-95 Measurements of Wavelength Shifts in Coronal Emission Lines Across a Solar Active Region Authors: Brosius, J. W.; Thomas, R. J.; Davila, J. M. Bibcode: 1999AAS...19410004B Altcode: 1999BAAS...31..997B We used slit spectra from the 1995 flight of Goddard Space Flight Center's Solar EUV Rocket Telescope and Spectrograph (SERTS-95) to measure wavelength shifts of coronal emission lines across the core of NOAA active region 7870 relative to its immediate surroundings (its ``edge"). This method circumvents the absence of reliable laboratory wavelengths for the observed lines by using lines from the edge spectrum as effective standards. We derived the SERTS-95 wavelength calibration from measurements of a post-flight laboratory spectrum containing 28 He II and Ne II EUV standard wavelengths known to high accuracy. Wavelength measurements for lines of He I, Ne III, and additional lines of Ne II in the laboratory calibration spectrum provide more accurate values than were previously available, enabling these lines also to serve as future calibration standards. Six solar lines were chosen for this study because they are free from known blends and are either intrinsically strong or near the SERTS-95 peak sensitivity: He II at 303.78 Angstroms, Fe XII at 193.51 Angstroms, Fe XIII at 202.05 Angstroms, Fe XIV at 211.33 Angstroms, Fe XV at 284.15 Angstroms, and Fe XVI at 335.41 Angstroms. The iron ions are the hottest ions ever used for this type of analysis. All six lines reveal statistically significant variations in their measured wavelength shifts across the active region core, including mixtures of blueshifts and redshifts, indicating a dynamic, turbulent corona. For each line we calculated weighted-average Doppler velocities, obtaining 3.3 +/- 1.1 km s(-1) for He II, 5.2 +/- 1.6 km s(-1) for Fe XII, 0.7 +/- 1.5 km s(-1) for Fe XIII, -2.1 +/- 1.4 km s(-1) for Fe XIV, 1.0 +/- 1.1 km s(-1) for Fe XV, and -1.1 +/- 0.8 km s(-1) for Fe XVI. This suggests a net upflow of heated material cospatially and cotemporally with a net downflow of cooler material. We acknowledge NASA support for this research. Title: Determination of the Reynolds number from TRACE Observation of Damped Coronal Loop Oscillations Induced by a Flare Authors: Ofman, L.; Nakariakov, V. M.; Deluca, E.; Roberts, B.; Davila, J. M. Bibcode: 1999AAS...194.7909O Altcode: 1999BAAS...31..964O The Transition Region and Coronal Expolorer (TRACE) observes the solar corona with unprecedented spatial and temporal resolution. We analyzed active region loop observation in the 171 Angstroms Fe IX emission line, and report the direct observations of damped transverse oscillations of a long (130+/-6 Mm) thin (diameter 2+/-0.36 Mm) bright active region loop. The oscillations were detected following a flare in the adjacent active region. We determined the oscillation frequency and the decay time by the least-square fit of an exponentially decaying sinusoidal function. Using the dispersion relation for the transverse oscillations, and the observed loop geometry we estimated the Alfven crossing time in the loop. The Alfven time can be used to determine the magnetic field strength in the loop if the density is known. All parts of the loop were observed to oscillate transversly in-phase, implying that the ocillation is a global mode of the loop. Using dissipative MHD model for resonant absorption of global mode oscillations for the coronal loop we determined the Reynolds number that produces the observed damping rate of the observed global mode. The value of the Reynolds number is in the 10(5-10^6) range, which is eight to nine orders of magnitude smaller than the classical coronal value. We discuss the important implication of the small Reynolds number on coronal heating theories. Title: The Advanced Solar Coronal Explorer Mission (ASCE) Authors: Kohl, J.; Cranmer, S.; Gardner, L.; Golub, L.; Raymond, J.; Smith, P. L.; Strachan, L.; Howard, R.; Moses, D.; Socker, D.; Wang, D.; Fisher, R. R.; Davila, J.; St. Cyr, C.; Noci, G.; Tondello, G. Bibcode: 1999AAS...194.6506K Altcode: 1999BAAS...31Q.928K The Advanced Solar Coronal Explorer (ASCE) mission was selected for a Phase A Concept Study in the current round of proposed MIDEX missions. It addresses three fundamental problems: 1) What physical processes heat coronal holes and drive the fast solar wind? 2) What physical processes heat streamers and drive the slow solar wind? and 3) How are coronal mass ejections (CMEs) heated and accelerated, and what role to they play in the evolution of the solar magnetic field. ASCE has two instruments, the Spectroscopic and Polarimetric Coronagraph (SPC) and the Extreme Ultraviolet Imager (EUVI). A deployable boom supports a distant external occulter that allows large aperture optics for the SPC coronagraphic channels. SPC's EUV channels will provide spectroscopy of the extended solar corona with 30 - 200 times the sensitivity of UVCS/SOHO and the first He II 30.4 nm spectroscopy of the extended corona. SPC's Large Aperture Spectroscopic Coronagraph channel will provide two orders of magnitude improvement in stray light suppression for wide field visible spectroscopy and 2 arcsec resolution elements for imaging and polarimetry. EUVI provides full disk imaging with 0.9 arcsec resolution elements and extremely high cadence. ASCE is designed to determine the thermal, kinetic, and wave energy densities in coronal structures, determine the rates of transformation among these forms of energy, their flow in space, and their loss to radiation, and determine the composition and ionization state of the corona in static and transient conditions. Title: The SERTS-97 rocket experiment to study activity on the Sun: flight 36.167-GS on 1997 November 18. Authors: Swartz, Marvin; Condor, Charles E.; Davila, Joseph M.; Haas, J. Patrick; Jordan, Stuart D.; Linard, David L.; Miko, Joseph J.; Nash, I. Carol; Novello, Joseph; Payne, Leslie J.; Plummer, Thomas B.; Thomas, Roger J.; White, Larry A.; Brosius, Jeffrey W.; Thompson, William T. Bibcode: 1999sret.book.....S Altcode: This paper describes mainly the 1997 version of the Solar EUV Rocket Telescope and Spectrograph (SERTS-97), a scientific experiment that operated on NASA's suborbital rocket flight 36.167-GS. Its function was to study activity on the Sun and to provide a cross calibration for the CDS instrument on the SOHO satellite. Title: Two-fluid 2.5D MHD Simulations of the Fast Solar Wind in Coronal Holes and the Relation to UVCS Observations Authors: Davila, J. M.; Ofman, L. Bibcode: 1999SSRv...87..165D Altcode: Recent SOHO/UVCS observations indicate that the perpendicular proton and ion temperatures are much larger than electron temperatures. In the present study we simulate numerically the solar wind flow in a coronal hole with the two-fluid approach. We investigate the effects of electron and proton temperatures on the solar wind acceleration by nonlinear waves. In the model the nonlinear waves are generated by Alfvén waves with frequencies in the 10-3 Hz range, driven at the base of the coronal hole. The resulting electron and proton flow profile exhibits density and velocity fluctuations. The fluctuations may steepen into shocks as they propagate away from the sun. We calculate the effective proton temperature by combining the thermal and wave velocity of the protons, and find qualitative agreement with the proton kinetic temperature increase with height deduced from the UVCS Ly-α observations by Kohl et al. (1998). Title: Spectroscopic study of the solar eclipse of August 1999 to understand the radial and latitudinal profiles of wind and temperature. Authors: Reginald, N. L.; Davila, J. M. Bibcode: 1999BAAS...31Q1241R Altcode: No abstract at ADS Title: Solar Active Region and Quiet-Sun Extreme-Ultraviolet Spectra from SERTS-95 Authors: Brosius, Jeffrey W.; Davila, Joseph M.; Thomas, Roger J. Bibcode: 1998ApJS..119..255B Altcode: Goddard Space Flight Center's Solar EUV Rocket Telescope and Spectrograph was flown on 1995 May 15 (SERTS-95), carrying a multilayer-coated toroidal diffraction grating that enhanced the instrumental sensitivity in its second-order wave band (171-225 Å). Spectra and spectroheliograms of NOAA active region 7870 (N09 W22) were obtained in this wave band with a spectral resolution (instrumental FWHM) ~30 mÅ and in the first-order wave band (235-335 Å) with a spectral resolution ~55 mÅ. Spectra and spectroheliograms of quiet-Sun areas northeast of the active region were also obtained. We derived the SERTS-95 relative radiometric calibration directly from flight data by means of density- and temperature-insensitive line intensity ratios. Most theoretical values for such ratios were obtained from the CHIANTI database. A total of 44 different lines were used to derive the relative radiometric calibration in the two spectral orders, most of them coming from seven (Fe X-Fe XVI) of the nine (Fe IX-Fe XVII) observed ionization stages of iron. The resulting relatively calibrated line intensities agree well with their corresponding normalized theoretical values. This supports the overall accuracy of the atomic physics parameters and demonstrates the power of the technique. The present work extends earlier work by Brosius, Davila, & Thomas, who determined the SERTS-95 second-order response using this technique. Many of the ratios employed here can be used to carry out a similar calibration exercise on spectra from the Coronal Diagnostic Spectrometer (CDS) aboard the Solar and Heliospheric Observatory (SOHO). We placed the line intensities onto an absolute scale by forcing our quiet-Sun He II λ303.8 + Si XI λ303.3 intensity to match that from previous observations. The resulting active region and quietSun absolutely calibrated line lists contain 127 and 20 lines, respectively. Active region densities derived from density-sensitive line intensity ratios of Fe X, XI, XIII, and XIV are mutually consistent with log ne ~ 9.4 +/- 0.2; densities derived from Fe XII are significantly greater (log ne ~ 10). Title: The SERTS-97 Cross-Calibration of CDS & EIT on SOHO Authors: Thomas, R. J.; Davila, J. M.; Thompson, W. T.; Kent, B. J.; Hollandt, J. Bibcode: 1998AAS...19310006T Altcode: 1998BAAS...30Q1398T GSFC's Solar EUV Rocket Telescope and Spectrograph (SERTS) obtains imaged high-resolution spectra of individual solar features, giving information about the Sun's corona and upper transition region. Its flight on 1997 November 18 had the additional goal of providing radiometric and wavelength calibrations for several experiments on the Solar and Heliospheric Observatory (SOHO) satellite mission. For that purpose, an end-to-end radiometric calibration of the rocket instrument was carried out at RAL in the same facility used to characterize the CDS experiment on SOHO, and using the same EUV light source specially re-calibrated by PTB against the primary standard BESSY synchrotron. Scans of the SERTS aperture over a range of pitch and yaw angles were made to determine the instrument's absolute spectral sensitivity to <= 25% at 12 wavelengths covering its range of 300 -- 365 Angstroms. Also, pre- and post-flight wavelength calibrations were done at GSFC using well known lines of He II and Ne II within the SERTS bandpass. For the first time, SERTS-97 carried an EUV solar flux monitor kindly provided by USC; its readings were used to validate our calculations of atmospheric EUV transmission over the rocket's trajectory. During the flight, SERTS-97 and CDS observed the same solar locations, as demonstrated by subsequent data co-registration with EIT images, allowing the SERTS calibrations to be directly applied to both CDS and EIT. Since SERTS clearly resolves the strong Si XI and He II lines blended in EIT's 304 Angstroms channel, SERTS measurements give information on the spectral composition of these images as well. Examples of the various cross-calibrations will be shown. Title: Solar wind acceleration by large-amplitude nonlinear waves: Parametric study Authors: Ofman, L.; Davila, J. M. Bibcode: 1998JGR...10323677O Altcode: We investigate the parametric dependence of the solar wind acceleration by large-amplitude nonlinear (LAN) magnetohydrodynamic waves. For this purpose we model numerically the self-consistent problem of the solar wind with waves by solving time-dependent, nonlinear, resistive 2.5-dimensional (three-dimensional with azimuthal symmetry) MHD equations driven by Alfvén waves. We find that when the Alfvén wave amplitude is above a parameter-dependent threshold, LAN waves are generated in the model coronal hole. For typical coronal parameters the solar wind speed and density fluctuate considerably on a timescale of ~10-40 min and with an amplitude of up to several hundred kmilometers per second near the Sun (r<~10RS) in agreement with recent interplanetary scintillation observations. The solar wind speed is inversely dependent on the driving frequency in the range 0.35-3 mHz. The amplitude of the velocity fluctuations increases with the amplitude of the magnetic field and the driving Alfvén waves at the base of the corona and decreases with the coronal temperature. We found that for the same typical solar wind and Alfvén wave parameters and an isothermal initial atmosphere, the WKB model predicts 30% higher flow velocities far from the Sun (32RS) than our self-consistent wave model with high-frequency Alfvén waves (f=2.78mHz), conforming to the WKB approximation. However, our model predicts significantly higher average flow speed near the Sun. When low-frequency non-WKB waves drive the wind, our model predicts 25% higher solar wind speed than the WKB model far from the Sun. This result of our model is in agreement with linear studies of solar wind acceleration by Alfvén waves that take into account Alfvén wave reflection. Title: Using Strong Solar Coronal Emission Lines as Coronal Flux Proxies Authors: Falconer, David A.; Jordan, Stuart D.; Brosius, Jeffrey W.; Davila, Joseph M.; Thomas, Roger J.; Andreatta, Vicenzo; Hara, Hirohisa Bibcode: 1998SoPh..180..179F Altcode: We investigate the possibility that strong EUV lines observed with the Goddard Solar EUV Rocket Telescope and Spectrograph (SERTS) provide good proxies for estimating the total coronal flux over shorter wavelength ranges. We use coordinated SERTS and Yohkoh observations to obtain both polynomial and power-law fits relating the broad-band soft X-ray fluxes to the intensities of Fexvi 335 Ú and 361 Ú, Fexv 284 Ú and 417 Ú, and Mgix 368 Ú measured with SERTS. We found that the power-law fits best cover the full range of solar conditions from quiet Sun through active region, though not surprisingly the `cooler' Mgix 368 Ú line proves to be a poor proxy. The quadratic polynomial fits yield fair agreement over a large range for all but the Mgix line. However, the linear fits fail conspicuously when extrapolated into the quiet-Sun regime. The implications of this work for the Heii 304 Ú line formation problem are also briefly considered. Title: Calibration of the SERTS-95 Spectrograph from Iron Line Intensity Ratios Authors: Brosius, Jeffrey W.; Davila, Joseph M.; Thomas, Roger J. Bibcode: 1998ApJ...497L.113B Altcode: Goddard Space Flight Center's Solar EUV Rocket Telescope and Spectrograph was flown on 1995 May 15 (SERTS-95), carrying a multilayer-coated toroidal diffraction grating which enhanced the instrumental sensitivity within its second-order wave band (170-225 Å). Spectra and spectroheliograms of NOAA Active Region 7870 (N09/W22) were obtained in this wave band with a spectral resolution (instrumental FWHM) ~30 mÅ. We developed and applied a technique for deriving the relative radiometric calibration independent of laboratory calibration measurements by employing a method proposed by Neupert & Kastner for monitoring variations in the sensitivities of orbiting EUV spectrometers by means of density- and temperature-insensitive line intensity ratios. Numerous ratios of emission lines from Fe X-XIV are mutually consistent and yield an instrumental response curve that matches the design characteristics of the multilayer coating. This supports the accuracy of the atomic physics parameters and demonstrates the power of the technique. Many of the ratios employed here can be used to carry out a similar calibration exercise on spectra from the Coronal Diagnostic Spectrometer's Grazing Incidence Spectrograph (CDS/GIS) aboard the Solar and Heliospheric Observatory. Because they are relatively free from blending with nearby strong lines, the following density-sensitive ratios are particularly well suited for analysis with the GIS: Fe X λ175.265/λ174.526, Fe X λ175.265/λ184.534, Fe XII λ186.867/λ195.117, Fe XIII λ203.820/λ202.042, Fe XIII λ200.017/λ202.042, and Fe XIV λ219.121/λ211.317. Densities derived from Fe X, XIII, and XIV yield log ne~9.4+/-0.2. Title: The Magnetic Reconnection Explorer (MAGREX) Authors: Schühle, U.; Antionchos, S. K.; Barbee, T. W., Jr.; Bixler, J. V.; Brown, C. M.; Carter, P. H., II; Curdt, W.; Davila, J. M.; Doschek, G.; Feldman, U.; Goldstein, W. H.; Kordas, J.; Lemaire, P.; Mariska, J. T.; Marsch, E.; Moses, J. D.; Seely, J. F.; Wilhelm, K.; Woods, T. N. Bibcode: 1998ESASP.417..289S Altcode: 1998cesh.conf..289S No abstract at ADS Title: Observing the inner heliosphere from new perspectives Authors: Davila, Joseph M. Bibcode: 1998AdSpR..21..319D Altcode: In the solar corona, the density scale height is large, a considerable fraction of a solar radius. Because of this, observations of the Sun from a single vantage point produce images which show an unavoidable overlapping of many structures along the line of sight. This makes it difficult, and sometimes impossible, to determine the true nature of the feature being observed. This difficulty can be overcome by obtaining simultaneous observations from multiple vantage points. Using these observations, and a reconstructions process similar to that used in medical imaging applications, the true three-dimensional nature of the solar corona can be deduced. The same process can be used to follow the formation of coronal mass ejections (CME's) in the low corona and the propagation of CME's through interplanetary space. Title: A Self-consistent Model for the Resonant Heating of Coronal Loops: The Effects of Coupling with the Chromosphere Authors: Ofman, L.; Klimchuk, J. A.; Davila, J. M. Bibcode: 1998ApJ...493..474O Altcode: We present the first model of resonant heating of coronal loops that incorporates the dependence of the loop density on the heating rate. By adopting the quasi-static equilibrium scaling law ρ ~ Q5/7, where ρ is the density and Q is the volumetric heating rate, we are able to approximate the well-known phenomena of chromospheric evaporation and chromospheric condensation, which regulate the coronal density. We combine this scaling law with a quasi-nonlinear MHD model for the resonant absorption of Alfvén waves in order to study the spatial and temporal dependence of the heating. We find that the heating is concentrated in multiple resonance layers, rather than in the single layer of previous models, and that these layers drift throughout the loop to heat the entire volume. These newfound properties are in much better agreement with coronal observations. Title: European Plans for the Solar/Heliospheric Stereo Mission Authors: Bothmer, V.; Bougeret, J. -L.; Cargill, P.; Davila, J.; Delaboudiniere, J. -P.; Harrison, R.; Koutchmy, S.; Liewer, P.; Maltby, P.; Rust, D.; Schwenn, R. Bibcode: 1998ESASP.417..145B Altcode: 1998cesh.conf..145B No abstract at ADS Title: Two-Component Winds from Luminous Late-Type Stars Authors: Airapetian, V. S.; Offman, L.; Robinson, R.; Carpenter, K.; Davila, J. Bibcode: 1998BAAS...30..760A Altcode: We present the results of a magnetohydrodynamic (MHD) simulation of winds from luminous late-type stars using a 2.5D, non-linear MHD computer code. In this simulation we assume that the wind is generated within a hydrostatic atmosphere with an initial isothermal pressure scale height of 0.072 Rstar and a radial magnetic field. We also assume a transverse density gradient which we we refer to as a ``chromospheric hole''. Tortional Alfven waves are generated at the stellar surface by a forcing function having a single frequency, which is comparable to the turn-over frequency of convective cells in giant stars. To ensure that we are accurately assessing the terminal velocity of the wind, we carried out the calculations to a height of 20 stellar radii and a time period of more than 180 Alfven transit times, which ensures that a steady state has been reached. In the higher density (low Alfven velocity) regions outside of the ``chromospheric hole'' the Alfven waves are freely propagating. Ponderomotive forces associated with these waves drive radial, compressive motions and contribute to stellar wind acceleration. The compressive motions then excite slow magnetosonic waves which non-linearly steepen into solitary waves that propagate on top of a background flow similar to the case of solar coronal holes. This produces a fast (40-80 km/s) and relatively dense component of the wind. In the lower density ``chromospheric hole'' region the Alfven waves are strongly reflected and produce an outflow with both radial and azimuthal velocities which are ~ 10% of the local Alfven speed. This component of the wind is slow ( ~ 10-30 km/s) and less dense than the wind initiated outside of the hole. Depending on the magnetic topology in the atmosphere of a luminous late - type star, we may therefore expect either one (fast) or two components to the wind. Our results are consistent with recent observations of two discrete components to the wind in the K5 III hybrid star gamma Dra. These components were detected in the Mg II h and k resonance lines and had velocities of 67 and 30 km/s, with the higher velocity component having a mass loss rate which is 10 times that of the slower speed wind. Title: Atmospheric Dynamics of Luminous Late-Type Stars Authors: Airapetian, V. S.; Ofman, L.; Robinson, R. D.; Carpenter, K.; Davila, J. Bibcode: 1998ASPC..154.1569A Altcode: 1998csss...10.1569A We present first results of magnetohydrodynamic (MHD) calculations of winds from luminous late-type stars using an existing, 2.5D, non-linear MHD code recently developed by Ofman & Davila (e.g., Ofman & Davila 1997). We assume that the wind is initiated in a hydrostatic atmosphere with an isothermal pressure scale height of 0.072 R* and a ``chromospheric hole'' modeled by a transverse density structure and a radial magnetic field. To ensure that we are accurately assessing the terminal velocity of the wind, we carried out the calculations to a height of 20 stellar radii. We find that in the higher density (low Alfven velocity) regions outside of the ``chromospheric hole'' the Alfven waves are freely propagating. Ponderomotive forces associated with these waves drive radial, compressive motions and contribute to stellar wind acceleration. The compressive motions then excite slow magnetosonic waves which non-linearly steepen into solitary waves that propagate on top of a background flow. This situation is similar to solar coronal hole models. In the lower density ``chromospheric hole'' region the Alfven wave are strongly reflected, and produce a substantial outflow, with both radial and azimuthal velocities approaching the local Alfven speed. Our results are in qualitative agreement with observational signatures of winds in cool, luminous late-type stars. Title: Coordinated Observations with SOHO/CDS and SERTS Authors: Thompson, W. T.; Thomas, R. J.; Davila, J. M.; Jordan, S. D.; Brosius, J. W. Bibcode: 1998AAS...191.7316T Altcode: 1998BAAS...30..758T On November 18, 1997, coordinated observations were made between the Coronal Diagnostic Spectrometer (CDS) aboard the Solar and Heliospheric Observatory (SOHO), and with the Solar Extreme-ultraviolet Rocket Telescope and Spectrograph (SERTS). One of the primary goals of this sounding rocket flight was to serve as a calibration underflight for SOHO. SERTS observes resolved spectra over most of the short wavelength channel of the CDS Normal Incidence Spectrograph, as well as the He II 304 Angstroms line which is observed by CDS in second order in the long wavelength channel. Observations were also made of the full sun with the SOHO Extreme ultraviolet Imaging Telescope (EIT) in its 304 Angstroms channel, allowing coalignment between all three instruments. EIT also serves as a transfer standard of the alignment to other full-sun observations. We will report on the status of the data analysis from the SERTS-97 flight, and its comparison to CDS. Title: IPS Observations of the Solar Wind Velocity and the Acceleration Mechanism Authors: Ofman, L.; Davila, J. M.; Coles, W. A.; Grall, R. R.; Klinglesmith, M. T. Bibcode: 1997ESASP.415..361O Altcode: 1997cpsh.conf..361O No abstract at ADS Title: The Measurement of Solar Active Region Properties with EUV Spectra and Spectroheliograms from SERTS Authors: Brosius, J. W.; Davila, J. M.; Thomas, R. J.; White, S. M. Bibcode: 1997AAS...191.7315B Altcode: 1997BAAS...29.1323B The Goddard Space Flight Center's Solar EUV Rocket Telescope and Spectrograph (SERTS) was successfully flown on six different occasions, and results from several of those flights are presented here. For the flight of 1995 May 15, SERTS included a multilayer coated toroidal diffraction grating which enhanced the throughput above that of a standard gold coated grating for wavelengths between about 170 and 220 Angstroms, with a peak response around 192 Angstroms. Emission lines in this wavelength range are seen in second order. First order lines between about 235 and 335 Angstroms are also detected. A total of nearly 140 lines are identifiable in the combined first and second order wavebands. These include lines from several ionization stages of Ca, Mg, Ni, S, and Si, as well as lines from at least nine ionization stages of Fe (IX -- XVII). Many of the lines are useful for calibration verification, plasma diagnostics, or both. Results from analyses of the high spectral resolution (30 m Angstroms in second order, and 55 m Angstroms in first), spatially resolved (4.4 arcsec spatial resolution) active region spectra are presented. For the flight of 1993 August 17, SERTS included a multilayer coated grating which enhanced the instrumental sensitivity within the first order waveband. For this flight we also obtained coordinated Very Large Array (VLA) radio observations at 20 and 6 cm wavelengths. Because the radio emission is sensitive to the coronal magnetic field while the EUV emission is not, we were able to derive solar coronal magnetograms from the combined SERTS and VLA observations. (This work was supported by NASA grants NASW-96006 and NASW-4933.) Title: Fast Solar Wind Acceleration by Nonlinear Waves in Coronal Holes Authors: Ofman, L.; Davila, J. M. Bibcode: 1997AAS...191.7414O Altcode: 1997BAAS...29.1326O We use the 2.5D (3D with azimuthal symmetry) MHD equations to model numerically the solar wind acceleration in a nonhomogeneous coronal hole. We investigate the parametric dependence of the solar wind acceleration by nonlinear MHD waves with a monochromatic and a broad band driving source. We find that when the Alfven wave amplitude is above a parameter dependent threshold , large amplitude nonlinear longitudinal waves are generated and contribute to the radial acceleration. The calculated solar wind speed and density fluctuates considerably on a time scale of tens of minutes with an amplitude of up to several hundred km/s near the sun (4R_sun<r<10R_sun). The amplitude of the fluctuations decreases with the distance from the sun. Using the monochromatic driver we find that the solar wind speed and the amplitude of the nonlinear waves is inversely dependent on the driving frequency in the range 0.3-3 mHz. The acceleration due to the broad band driver depends on the power spectrum of the driver. The amplitude of the nonlinear waves and the acceleration increases with the magnitude of the magnetic field and decreases with the temperature of the coronal hole. Title: Results from the November 1997 Flight of the Solar Extreme-ultraviolet Rocket Telescope and Spectrograph (SERTS) Authors: Davila, J. M.; Thomas, R. J.; Swartz, M.; Condor, C.; Linard, D., II; Haas, P.; Miko, J.; Payne, L. Bibcode: 1997AAS...191.7312D Altcode: 1997BAAS...29.1322D The SERTS current instrument obtains spatially resolved spectra of the Sun in the wavelength range of 300-350 Angstroms. These spectra provide information on the density and temperature of the solar corona in the temperature range of 50,000 K to 5,000,000 K. The SERTS instrument has been flown before, however the unique aspect of the most recent flight is the opportunity to obtain fully calibrated spectral data. (See companion paper on the calibration procedure by R. Thomas, et al.) In additon during this flight co-observation with SOHO as well as Yohkoh and the VLA will be obtained. The first look at these results will be presented and discussed. Title: Coronal Magnetography of a Solar Active Region Using Coordinated SERTS and VLA Observations Authors: Brosius, Jeffrey W.; Davila, Joseph M.; Thomas, Roger J.; White, Stephen M. Bibcode: 1997ApJ...488..488B Altcode: We observed NOAA region 7563 simultaneously with Goddard Space Flight Center's Solar EUV Rocket Telescope and Spectrogaph (SERTS) and with the Very Large Array (VLA) on 1993 August 17. SERTS obtained spectra in the 280-420 Å wavelength range, and images in the lines of Mg IX λ368.1, Fe XV λ284.1, and Fe XVI λ335.4. The VLA obtained microwave images at 20 and 6 cm wavelengths. The microwave emission depends upon the coronal temperature, density, column emission measure, and magnetic field; therefore, the coronal magnetic field can be derived when all of these other quantities are measured. Here we demonstrate this approach by using the SERTS data to derive all the relevant plasma parameters and then fitting the radio observations to a magnetic field model in order to determine the magnetic field structure.

We used the method of Monsignori-Fossi & Landini and the coronal elemental abundances of Feldman et al. to derive the differential emission measure (DEM) curve for region 7563 from numerous EUV emission lines in spatially averaged SERTS spectra. A similar curve was estimated for each point (i.e., each pixel or each spatial location) in the two-dimensional region by scaling the average DEM curve with corresponding pixel intensities in the Mg IX, Fe XV, and Fe XVI images. We integrated each such DEM over narrow temperature ranges to obtain the column emission measure (CEM) as a function of temperature, CEM(T). We also obtained electron density measurements from EUV line intensity ratios in the spatially averaged spectrum for several ionization stages of iron. These were used to derive a functional relation between density and temperature, ne(T).

We derived the temperature dependence of the coronal magnetic field [B(T)] at each point in the two-dimensional region by incorporating CEM(T) and ne(T) into expressions for the thermal bremsstrahlung and the gyroresonance opacities, and varying B(T) so as to minimize the difference between the calculated and the observed microwave intensities. The resulting calculated 20 and 6 cm microwave intensity images reproduce the observed images very well. We found that thermal bremsstrahlung alone is not sufficient to produce the observed microwave intensities: gyroemission is required. Further, contrary to several earlier studies, we found no evidence for cool, absorbing plasma in the solar corona above the active region. The coronal magnetic fields derived with our method typically exceed the coronal fields extrapolated with a simple potential model, suggesting the presence of coronal electric currents. However, in the diminutive sunspot which dominates the 6 cm emission this difference is relatively small, suggesting that the sunspot magnetic field itself is nearly potential. Although we cannot firmly establish the uniqueness of our solution in this particular case, the method is quite powerful and should be repeated with other similar data sets. Variations in the coronal elemental abundances could affect the determination of the microwave emission mechanism(s), introduce evidence for the presence of cool coronal plasma, and alter the strengths of the derived coronal magnetic fields. Title: Obtaining the 3D Structure of Coronal Magnetic Loops from Stereo Observations Authors: Davila, Joseph M. Bibcode: 1997BAAS...29Q1119D Altcode: No abstract at ADS Title: The Solar-B Mission Authors: Antiochos, Spiro; Acton, Loren; Canfield, Richard; Davila, Joseph; Davis, John; Dere, Kenneth; Doschek, George; Golub, Leon; Harvey, John; Hathaway, David; Hudson, Hugh; Moore, Ronald; Lites, Bruce; Rust, David; Strong, Keith; Title, Alan Bibcode: 1997STIN...9721329A Altcode: Solar-B, the next ISAS mission (with major NASA participation), is designed to address the fundamental question of how magnetic fields interact with plasma to produce solar variability. The mission has a number of unique capabilities that will enable it to answer the outstanding questions of solar magnetism. First, by escaping atmospheric seeing, it will deliver continuous observations of the solar surface with unprecedented spatial resolution. Second, Solar-B will deliver the first accurate measurements of all three components of the photospheric magnetic field. Solar-B will measure both the magnetic energy driving the photosphere and simultaneously its effects in the corona. Solar-B offers unique programmatic opportunities to NASA. It will continue an effective collaboration with our most reliable international partner. It will deliver images and data that will have strong public outreach potential. Finally, the science of Solar-B is clearly related to the themes of origins and plasma astrophysics, and contributes directly to the national space weather and global change programs. Title: Relative Elemental Abundances of the Quiet Solar Corona as Determined by SERTS Authors: Falconer, D. A.; Davila, J. M.; Thomas, R. J. Bibcode: 1997ApJ...482.1050F Altcode: Intensities of extreme-ultraviolet (EUV) spectral lines were measured as a function of radius off the solar limb by two flights (1989 May 5 and 1991 May 7) of the Solar Extreme-ultraviolet Rocket Telescope and Spectrograph (SERTS) for three quiet solar regions. The line-ratio density, line-ratio temperature, and emission measure were determined. The relative abundances of silicon, aluminum, and chromium to iron were determined. Results agreed with standard coronal relative elemental abundances for one observation, but did not agree for the other, in which aluminum was overabundant. Title: Coronal Magnetography of a Solar Active Region Using Coordinated SERTS and VLA Observations Authors: Brosius, J. W.; Davila, J. M.; Thomas, R. J.; White, S. M. Bibcode: 1997SPD....28.0135B Altcode: 1997BAAS...29..885B We observed NOAA region 7563 simultaneously with Goddard Space Flight Center's Solar EUV Rocket Telescope and Spectrograph (SERTS) and with the Very Large Array (VLA) on 1993 August 17. SERTS obtained spectra in the 280 to 420 Angstroms wavelength range, and images in the lines of Mg IX lambda 368.1, Fe XV lambda 284.1, and Fe XVI lambda 335.4. The VLA obtained microwave images at 20 and 6 cm wavelengths. The microwave emission depends upon the coronal temperature, density, column emission measure, and magnetic field; therefore, the coronal magnetic field can be derived when all of these other quantities are measured. Here we demonstrate this approach by using the SERTS data to derive all the relevant plasma parameters and then fitting the radio observations to a magnetic field model in order to determine the magnetic field structure. We derived the temperature dependence of the coronal magnetic field (B(T)) at each point (i.e., each pixel or each spatial location) in the two dimensional region by incorporating the corresponding column emission measure (CEM(T)) and electron density (n_e(T)) into expressions for the thermal bremsstrahlung and gyroresonance opacities, and varying B(T) so as to minimize the difference between the calculated and the observed microwave intensities. The resulting calculated 20 and 6 cm microwave intensity images reproduce the observed images very well. Thermal bremsstrahlung emission alone is not sufficient to produce the observed microwave intensities: gyroemission is required. Further, contrary to several earlier studies, we found no evidence for cool, absorbing plasma in the solar corona above the active region. The coronal magnetic fields derived with our method typically exceed the coronal fields extrapolated with a simple potential model, suggesting the presence of coronal electric currents. However, in the diminutive sunspot which dominates the 6 cm emission this difference is relatively small, suggesting that the sunspot magnetic field itself is nearly potential. (This work was supported by NASA grant NASW-4933.) Title: A Self-Consistent Model for the Resonant Heating of Coronal Loops: the Effects of Coupling with the Chromosphere Authors: Klimchuk, J. A.; Ofman, L.; Davila, J. M. Bibcode: 1997SPD....28.0504K Altcode: 1997BAAS...29..909K The physical nature of coronal heating remains one of the great problems of solar physics. One of the several theories that are being pursued is the resonant absorption of MHD waves. While promising in several respects, this theory has suffered from a glaring deficiency: the computed heating is incompatible with both the assumed density and the observed structure of coronal loops. We present the first model of resonant heating of coronal loops that incorporates the dependence of the loop density on the heating rate. By adopting the quasi-static equilibrium scaling law rho ~ Q(5/7) , where rho is the density and Q is the volumetric heating rate, we are able to approximate the well-known phenomena of chromospheric evaporation and chromospheric condensation, which regulate the coronal density. We combine this scaling law with a linearized MHD model for the resonant absorption of Alfven waves to study the spatial and temporal dependence of the heating. We find that the heating is concentrated in multiple resonance layers, rather than the single layer of previous models, and that these layers drift throughout the loop to heat the entire volume. These new properties are in much better agreement with coronal observations, including recent observations from the CDS and EIT instruments on SOHO, as well as earlier observations from the SXT instrument on Yohkoh. Title: The Structure and Properties of Solar Active Regions and Quiet-Sun Areas Observed in Soft X-Rays with Yohkoh/SXT and in the Extreme-Ultraviolet with SERTS Authors: Brosius, Jeffrey W.; Davila, Joseph M.; Thomas, Roger J.; Saba, Julia L. R.; Hara, Hirohisa; Monsignori-Fossi, Brunella C. Bibcode: 1997ApJ...477..969B Altcode: We observed two solar active regions (NOAA regions 7563 and 7565), quiet-Sun areas, and a coronal hole region simultaneously with Goddard Space Flight Center's Solar EUV Rocket Telescope and Spectrograph (SERTS) and with the Yohkoh Soft X-ray Telescope (SXT) on 1993 August 17. SERTS provided spatially resolved active region and quiet-Sun slit spectra in the 280 to 420 Å wavelength range, and images in the lines of He II λ303.8, Mg IX λ368.1, Fe XV λ284.1, and Fe XVI λλ335.4 and 360.8 SXT provided images through multiple broadband filters in both the full-frame imaging mode and the partial-frame imaging mode.

The SERTS images in Fe XV (log Tmax = 6.33, where Tmax is the temperature which maximizes the fractional ion abundance in the available ionization equilibrium calculations, i.e., the formation temperature) and Fe XVI (log Tmax = 6.43) exhibit remarkable morphological similarity to the SXT images. Whereas the Fe XV and XVI images outline the loop structures seen with SXT, the cooler He II (log Tmax = 4.67) and Mg IX (log Tmax = 5.98) images outline loop footpoints. In addition, the Mg IX emission outlines other structures not necessarily associated with the hot loops; these may be cool (T <~ 1 × 106 K) loops.

From the spatially resolved slit spectra, we obtained emission-line profiles for lines of He II λ303.8, Mg IX λ368.1, Fe XIII λ348.2, Si XI λ303.3, Fe XIV λ334.2, Fe XV λ284.1, and Fe XVI λ335.4 for each spatial position. Based upon the spatial variations of the line intensities, active region 7563 systematically narrows when viewed with successively hotter lines, and appears narrowest in the broadband soft X-ray emission. The active region width (full width at half-maximum intensity) diminishes linearly with log Tmax; the linear fit yields an extrapolated effective log Tmax of 6.51 +/- 0.01 for the X-ray emission. The most intense, central core straddles the magnetic neutral line.

Active region and quiet-Sun one-dimensional temperature scans were derived from intensity ratios of spatially resolved SERTS slit spectral lines, and from coregistered SXT filter ratios. The highest plasma temperatures were measured in the most intense, central core of region 7563. The temperatures derived from Fe XVI λ335.4/Fe XV λ284.1 and Fe XVI λ335.4/Fe XIV λ334.2 vary significantly (based upon the measurement uncertainties) but not greatly (factors of less than 1.5) across the slit. The average log T values derived from the above two ratios for region 7563 are 6.39 +/- 0.04 and 6.32 +/- 0.02, respectively. Somewhat larger systematic variations were obtained from all available SXT filter ratios. The average active region log T values derived from the SXT AlMgMn/thin Al, thick Al/thin Al, and thick Al/AlMgMn filter ratios are 6.33 +/- 0.03, 6.45 +/- 0.02, and 6.49 +/- 0.03, respectively.

Active region and quiet-Sun one-dimensional density scans were derived from intensity ratios of spatially resolved SERTS slit spectral lines of Fe XIII and Fe XIV. The derived densities show neither systematic nor significant variations along the slit in either the active region or the quiet-Sun, despite the fact that the intensities themselves vary substantially. This indicates that the product of the volume filling factor and the path length (fΔl) must be greater by factors of 3-5 in the active region core than in the outskirts. Furthermore, the derived active region densities are ~2 times the quiet-Sun densities. This density difference is adequate to explain the factor of ~4 intensity difference in Fe XII and Fe XIII between the active and quiet areas, but it is not adequate to explain the factor of ~8 intensity difference in Fe XIV between the active and quiet areas. We attribute the latter to a greater fΔl in the active regions.

Statistically significant Doppler shifts are not detected in region 7563 or in the quiet-Sun with any of the EUV lines. Title: Do First Results from SOHO UVCS Indicate That the Solar Wind Is Accelerated by Solitary Waves? Authors: Ofman, L.; Davila, J. M. Bibcode: 1997ApJ...476L..51O Altcode: The Ultraviolet Coronagraph Spectrometer (UVCS) on board the recently launched US-European Solar and Heliospheric Observatory (SOHO) satellite has found O VI and H I emission lines with a broad component that corresponds to ~300 km s-1 unresolved motions at about 0.7 solar radii above the photosphere. These motions appear to be independent of ion mass. We suggest that the large Doppler broadening of the ion emission lines observed by the UVCS are signatures of solitary waves in the solar wind plasma. According to our recent 2.5-dimensional (i.e., three-dimensional with azimuthal symmetry) MHD simulations, these waves may contribute significantly to the solar wind acceleration and may generate velocity fluctuations with a magnitude that agrees with the above observations. Title: Solar Wind Acceleration by Solitary Waves in Coronal Holes Authors: Ofman, L.; Davila, J. M. Bibcode: 1997ApJ...476..357O Altcode: Coronal holes are well-known sources of the high-speed solar wind; however, the exact acceleration mechanism of the fast wind is still unknown. We solve numerically the time-dependent, nonlinear, resistive 2.5-dimensional MHD equations and find that solitary waves are generated in coronal holes nonlinearly by torsional Alfvén waves. The solitary wave phase velocity was found to be slightly above the sound speed in the coronal hole; for example, with the driving Alfvén wave amplitude vd ~ 36 km s-1 and plasma β = 5%, the solitary wave phase speed is ~185 km s-1. We show with a more simplified analytical model of the coronal hole that sound waves are generated nonlinearly by Alfvén waves. We find numerically that these waves steepen nonlinearly into solitary waves. In addition, ohmic heating takes place in the coronal hole inhomogeneities owing to phase-mixing of the torsional Alfvén waves. When solitary waves are present, the solar wind speed and density fluctuate considerably on timescales of ~20-40 minutes in addition to the Alfvénic fluctuations. The solitary wave-driven wind might be in better qualitative agreement with observations than the thermally driven and WKB Alfvén wave solar wind models. Title: Possible Signatures of Nonlinear MHD Waves in the Solar Wind: UVCS Observatio ns and Models Authors: Ofman, L.; Romoli, M.; Davila, J. M.; Poletto, G.; Kohl, J.; Noci, G. Bibcode: 1997ESASP.404..571O Altcode: 1997cswn.conf..571O No abstract at ADS Title: Solitary waves in coronal holes-predicted signatures close to the sun Authors: Ofman, L.; Davila, J. M. Bibcode: 1997AIPC..385..227O Altcode: 1997recs.conf..227O Coronal holes are well known sources of the high speed solar wind, however, the exact acceleration mechanism of the wind is still unknown. We find that solitary waves may be generated in coronal holes nonlinearly by Alfvén waves. The solitary waves may efficiently accelerate the fast solar wind in addition to thermal conduction. We solve numerically the time-dependent, nonlinear, resistive 2.5-D MHD equations in spherical geometry with azimuthal symmetry to model solar wind acceleration by waves in coronal holes. Torsional Alfvén waves are driven at the base of the model coronal hole and propagate into the corona. Ohmic heating layers are found to occur at the coronal hole boundaries due to phase-mixing of the torsional Alfvén waves. The nonlinear coupling of the perpendicular (to the background magnetic field) components of the velocity and the magnetic field to the radial component of the momentum equation leads to the acceleration of the solar wind in the radial direction and to the generation of solitary waves. The solitary wave phase velocity was found to be above the sound speed in the coronal hole, with the driving Alfvén wave amplitude vd~25 km s-1, and plasma β=2.5%. We discuss the implication of our results to the proposed in-situ observations in the region r<10Rs with the future solar probe mission. Title: A New Mechanism for Solar Wind Acceleration Authors: Ofman, L.; Davila, J. M. Bibcode: 1997IAUJD..19E..34O Altcode: We investigate the parametric dependence of a new solar wind acceleration mechanism by nonlinear magneto-hydrodynamic waves, by solving numerically the time-dependent, nonlinear, resistive 2.5-D MHD equations. We find that large amplitude nonlinear longitudinal waves are generated in coronal holes by torsional Alfven waves for a broad range of parameters in the 10^6 K magnetized plasma. The structure and the dependence of the phase speed on the amplitude of these waves are similar to solitary waves. We find that the solar wind speed and density fluctuate considerably on a time scales of ~20-40 min with an amplitude of several hundred km s^{-1}. The amplitude of the radial velocity fluctuations increases with the amplitude of the driving torsional Alfven waves at the base of the corona and the magnetic field strength, decreases with the temperature, and nearly independent of the driving frequency. The typical driving frequency of the Alfven waves is in the mHz range, determined by wave reflection in the radially stratified coronal hole, with an amplitude of 30-60 km s^{-1}. For typical coronal hole parameters the nonlinear wave driven wind accelerates to more than twice the Parker's solar wind speed and is in qualitative agreement with recent SOHO observations. Title: The structure of the solar corona as observed by the Solar Extreme Ultraviolet Rocket Telescope and Spectrograph Authors: Davila, Joseph M.; Thomas, Roger J.; Brosius, Jeffrey; Poland, Arthur Bibcode: 1997AdSpR..20.2293D Altcode: Data from the Solar Extreme-ultraviolet Rocket Telescope and Spectrograph (SERTS) have been used to address a number of important scientific problems. The primary strength of the SERTS data is the fact that this spectral range is rich with emission lines. Over 270 lines are seen in the SERTS active Sun spectrum, from 57 different ions. For example, multiple (>= 4) lines are observed for all ionization states of iron from Fe IX to Fe XVII. Temperatures and densities have been derived for a number of active and quiet Sun regions, the coronal magnetic field strength has been estimated for both a plage region and an active region. Title: STEREO: a solar terrestrial event observer mission concept Authors: Socker, Dennis G.; Antiochos, S. K.; Brueckner, Guenter E.; Cook, John W.; Dere, Kenneth P.; Howard, Russell A.; Karpen, J. T.; Klimchuk, J. A.; Korendyke, Clarence M.; Michels, Donald J.; Moses, J. Daniel; Prinz, Dianne K.; Sheely, N. R.; Wu, Shi T.; Buffington, Andrew; Jackson, Bernard V.; Labonte, Barry; Lamy, Philippe L.; Rosenbauer, H.; Schwenn, Rainer; Burlaga, L.; Davila, Joseph M.; Davis, John M.; Goldstein, Barry; Harris, H.; Liewer, Paulett C.; Neugebauer, Marcia; Hildner, E.; Pizzo, Victor J.; Moulton, Norman E.; Linker, J. A.; Mikic, Z. Bibcode: 1996SPIE.2804...50S Altcode: A STEREO mission concept requiring only a single new spacecraft has been proposed. The mission would place the new spacecraft in a heliocentric orbit and well off the Sun- Earth line, where it can simultaneously view both the solar source of heliospheric disturbances and their propagation through the heliosphere all the way to the earth. Joint observations, utilizing the new spacecraft and existing solar spacecraft in earth orbit or L1 orbit would provide a stereographic data set. The new and unique aspect of this mission lies in the vantage point of the new spacecraft, which is far enough from Sun-Earth line to allow an entirely new way of studying the structure of the solar corona, the heliosphere and solar-terrestrial interactions. The mission science objectives have been selected to take maximum advantage of this new vantage point. They fall into two classes: those possible with the new spacecraft alone and those possible with joint measurements using the new and existing spacecraft. The instrument complement on the new spacecraft supporting the mission science objectives includes a soft x-ray imager, a coronagraph and a sun-earth imager. Telemetry rate appears to be the main performance determinant. The spacecraft could be launched with the new Med-Lite system. Title: Tomography of the solar corona and the inner heliosphere: the solar imaging of coronal extended structures (SLICES) Authors: Davila, Joseph M. Bibcode: 1996SPIE.2804...62D Altcode: In the solar corona, the density scale height is large, a considerably fraction of a solar radius. Because of this, observations of the Sun from a single vantage point produce images which show an unavoidable overlapping of many structures along the line of sight. This makes it difficult, and sometimes impossible, to determine the true nature of the feature being observed. This difficulty can be overcome by obtaining simultaneous observations from multiple vantage points. Using these observations, and a reconstructions process similar to that used in medical imaging applications, the true 3D nature of the solar corona can be deduced. The same process can be used to follow the formation of coronal mass ejections (CME's) in the low corona and the propagation of CME's through interplanetary space. Title: Conceptual design for a solar instrument on the proposed SPARTAN Lite spacecraft Authors: Amato, Michael; Thomas, Roger J.; Davila, Joseph M.; Polidan, Ronald S. Bibcode: 1996SPIE.2804..206A Altcode: Spartan Lite is a proposed series of very low-cost spacecraft missions which offer potential flight opportunities for pointed solar experiments. Early versions will be launched as Space Shuttle attached payloads with the capability of being released for free flight. They would not be recovered, allowing useful lifetimes of six months to one year. An expendable launch vehicle option will be added later. The spacecraft is 3-axis stabilized with a cylindrical instrument cavity 100 cm long and 36 cm in diameter. If approved, the program would provide multiple launch opportunities during the upcoming solar maximum. A conceptual instrument design for a solar pointed mission on Spartan Lite is shown and discussed. The Extreme-Ultraviolet Normal Incidence Spectrograph will observe the solar spectrum between 290 and 466 A with high spatial and spectral resolutions. The large bandpass is due to the compact design, fitting two optical systems into the instrument cavity, each observing a different, but overlapping, wavelength range. Title: Solar Terrestrial Relations Observatory (STEREO) Authors: Davila, Joseph M.; Rust, David M.; Pizzo, Victor J.; Liewer, Paulett C. Bibcode: 1996SPIE.2804...34D Altcode: The solar output changes on a variety of timescales, from minutes, to years, to tens of years and even to hundreds of years. The dominant timescale of variation is, of course, the 11-year solar cycle. Observational evidence shows that the physics of solar output variation is strongly tied to changes in the magnetic field, and perhaps the most dramatic manifestation of a constantly changing magnetic field is the Coronal Mass Ejection (CME). On August 5 - 6, 1996 the Second Workshop to discuss missions to observe these phenomena from new vantage points, organized by the authors, was held in Boulder, Colorado at the NOAA Space Environmental Center. The workshop was attended by approximately 20 scientists representing 13 institutions from the United States and Europe. The purpose of the Workshop was to discuss the different concepts for multi- spacecraft observation of the Sun which have been proposed, to develop a list of scientific objectives, and to arrive at a consensus description of a mission to observe the Sun from new vantage points. The fundamental goal of STEREO is to discover how coronal mass ejections start at the Sun and propagate in interplanetary space. The workshop started with the propositions that coronal mass ejections are fundamental manifestations of rapid large-scale change in the global magnetic structure of the Sun, that CME's are a major driver of coronal evolution, and that they may play a major role in the solar dynamo. Workshop participants developed a mission concept that will lead to a comprehensive characterization of CME disturbances through build-up, initiation, launch, and propagation to Earth. It will also build a clear picture of long-term evolution of the corona. Participants in the workshop recommended that STEREO be a joint mission with the European scientific community and that it consist of four spacecraft: `East' at 1 AU near L4, 60 deg from EArth to detect active regions 5 days before they can be seen by terrestrial telescopes. `West' at L5 views the sources of energetic particle events reaching Earth. `Earth Orbiter' to view the Sun, solar plasma and Earth's magnetosphere, and `North-South' in a 1 AU orbit tilted 30 deg from the ecliptic plane to provide measurements of polar fields and high-latitude activity. All spacecraft will carry solar activity imagers (e.g., EUV telescope and white-light coronagraph) and radio burst detectors to support a tomography program. All will carry sensitive polarimeters that will image CME's from 40 solar radii to 1 AU, and all will carry instruments for situ plasma and energetic particle sampling. East and North-South have solar vector magnetographs. Title: Coronal Temperature, Density and Nonthermal Velocity Derived from SERTS EUV Spectra Authors: Moon, Yong-Jae; Yun, Hong Sik; Davila, J. M.; Park, Young Deuk Bibcode: 1996JKAS...29..207M Altcode: To derive coronal temperature, electron density and nonthermal velocity, we have analyzed high resolution spectra (e.g., Fe XII 338.3, Fe XII 352.1, Fe XIV 334.2, Fe XIV 353.8, Fe XV 284.2, Fe XV 321.8, Fe XV 327.0, Fe XVI 335.4, and Fe XVI 360.8) taken from AR 6615 by SERTS (Solar Extreme Ultraviolet Rocket Telescope and Spectrograph). Important findings emerging from the present study are as follows: (1) Temperature estimated from Fe XVI 335.4 and Fe XIV 334.2 is about 2.4 times 10E6 K and no systematic difference in temperature is found between the active region and its adjacent quiet region; (2) Mean electron density estimated from Fe XV is about 3*10E9/cm3 and about 10E10/cm3 from Fe XII and Fe XIV; (3) Mean density of the active region is found to be higher than that of the quiet region by a factor of 2; (4) Nonthermal velocity estimated from Fe XV and Fe XVI is 20-25 km/s which decreases with increasing ionization temperatures. This supports the notion that the nonthermal velocity declines outwards above the transition region. Title: Measuring Active and Quiet-Sun Coronal Plasma Properties with Extreme-Ultraviolet Spectra from SERTS Authors: Brosius, Jeffrey W.; Davila, Joseph M.; Thomas, Roger J.; Monsignori-Fossi, Brunella C. Bibcode: 1996ApJS..106..143B Altcode: We obtained high-resolution extreme-ultraviolet (EUV) spectra of solar active regions, quiet-Sun areas, and off-limb areas during 1991 May 7 and 1993 August 17 flights of NASA/Goddard Space Flight Center's Solar EUV Rocket Telescope and Spectrograph (SERTS). The 1991 flight was the first time a multilayer coated diffraction grating was ever used in space. Emission lines from the eight ionization stages of iron between Fe+9 (Fe x) and Fe+16 (Fe XVII) were observed. Values of numerous density- and temperature-insensitive line intensity ratios agree with their corresponding theoretical values.

Intensity ratios among various lines originating in a common stage of ionization provide measurements of coronal electron density. Numerous density-sensitive ratios are available for Fe xiii, and they yield active region density (cm-3) logarithms of 9.66±0.49 and 9.60±0.54 for the 1993 and 1991 flights, respectively, and a quiet-Sun density of 9.03±0.28 for the 1993 flight. Filling factors, calculated from the derived densities assuming a path length of 1 × 109 cm, range from several thousandths to nearly unity.

Intensity ratios among lines originating in different ionization stages of iron yield measurements of coronal electron temperature in the isothermal approximation. The line ratios yield temperatures ranging from 1.1 × 106 to 5.2 × 106 K for the active regions, and 1.0 × 106 to 2.1 × 106 K for the quiet Sun, depending upon the ionization stages used. The derived temperature diminishes with decreasing ionization stages. Fe XVII emission, detected in the active regions but not in the quiet areas, accounts for the higher maximum active region temperature. Derived active region temperatures are greater than their quiet-Sun counterparts for ratios that include lines from Fe xiv through Fe XVI; however, the derived active region and quiet-Sun temperatures are not statistically significantly different for line intensity ratios that involve only Fe x through Fe xiii. The latter similarity in derived temperatures suggests the presence of similar thermal structures in all the areas observed, although the active regions also harbor hotter material.

Differential emission measure (DEM) distributions were constructed for the active region and quiet- Sun observations obtained during both flights. The two quiet-Sun DEM curves and the 1993 active region DEM curve all show peaks between log T = 6.1 and 6.2. The 1993 active region DEM has a second peak between log T = 6.6 and 6.7, and the 1991 active region DEM has only one peak, between log T = 6.5 and 6.6. Thus, the 1993 active region DEM curve appears, in some sense, to be a composite of the quiet-Sun DEM curve and the 1991 active region DEM curve. The 1991 active region exhibited flaring activity, yielded higher line ratio temperatures, and contained greater photo spheric magnetic fields than the 1993 active region. Title: Heating of coronal holes by the resonant absorption and dissipation of Alfvén waves Authors: Ofman, L.; Davila, J. M. Bibcode: 1996AIPC..382..149O Altcode: Coronal hole regions are well known sources of high-speed solar wind, however to account for the observed properties of the solar wind a source of energy must be included in addition to heat conduction. Alfvén waves were suggested as the possible source of heating that accelerates the solar wind. We investigate the heating and propagation of Alfvén waves in coronal holes via 2-D MHD simulation in slab geometry. Resonance heating layers are found to occur when shear Alfvén waves are driven at the coronal boundary and a continuous density profile is assumed for the coronal hole. The heating is enhanced by phase mixing when coronal hole inhomogeneities (i.e., plumes) are included. We investigate the dependence of the heating rate on the driver frequency and the Lundquist number S and find a good agreement with the analytical S1/3 scaling of the dissipation length for uniform background magnetic field. We find that when S=104 the low frequency Alfvén waves can be a significant source of heating of coronal holes at several solar radii. At larger values of S nonlinear effects may reduce the effective dissipation length. We also find that the radial dependence of the heating rate has the same form as the observed scale height temperature radial profiles observed by SPARTAN 201-01. Title: Long-period oscillations of the sun's interior Authors: Davila, Joseph M.; Chitre, S. M. Bibcode: 1996BASI...24..309D Altcode: No abstract at ADS Title: The Structure and Properties of Solar Active Regions and Quiet Sun Areas Observed With SERTS and YOHKOH Authors: Brosius, J. W.; Davila, J. M.; Thomas, R. J.; Hara, H. Bibcode: 1996AAS...188.3715B Altcode: 1996BAAS...28..880B We observed solar active regions, quiet sun areas, and a coronal hole simultaneously with Goddard Space Flight Center's Solar EUV Rocket Telescope and Spectrograph (SERTS), and with the Yohkoh Soft X-Ray Telescope (SXT) on 1993 August 17. SERTS provided spatially resolved active region and quiet sun spectra in the 280 to 420 Angstroms wavelength range, and images in the lines of He II 304 Angstroms, Mg IX 368 Angstroms, Fe XV 284 Angstroms, and Fe XVI 335 Angstroms and 360 Angstroms. The SERTS waveband is accessible to CDS, SUMER, and EIT on SOHO. SXT provided images through multiple broadband filters. The SERTS images in Fe XV (T=2 MK) and XVI (T=2.5 MK) exhibit remarkable morphological similarity to the SXT images. Whereas the Fe XV and XVI images outline the loop structures seen with SXT, the cooler He II (T=0.1 MK) and Mg IX (T=1 MK) images seem to outline loop footpoints. From the spatially resolved spectra, we obtained emission line profiles for lines of Fe X (1 MK) through Fe XVI, and Mg IX and Ni XVIII (3.2 MK) for each spatial position. Based upon the spatial variations of the line intensities, the active region systematically narrows as it is viewed with successively hotter lines. The active region appears narrowest in the X-ray emission, which is consistent with our understanding that Yohkoh is most sensitive to the hottest plasma in its line of sight. EUV emission from Fe XVII (T=5 MK) is weak but detectable in the active region core. The most intense, central core straddles the magnetic neutral line. Temperature maps obtained with SERTS image ratios and with SXT filter ratios are compared. Line intensity ratios indicate that the active region temperature is greatest in the central core, but that the density varies very little across the region. Significant Doppler shifts are not detected in the EUV lines. Title: Acceleration of the Solar Wind by Solitary Waves in Coronal Holes Authors: Ofman, L.; Davila, J. M. Bibcode: 1996AAS...188.8602O Altcode: 1996BAAS...28..963O Coronal holes are well known sources of the high speed solar wind, however, the exact acceleration mechanism of the wind is still unknown. We solve numerically the time-dependent, nonlinear, resistive 2(1)/(2)-D MHD equations and find that solitons are generated in coronal holes nonlinearly by torsional Alfven waves. Initially, the ponderomotive force due to Alfven waves excites longitudinal magnetosonic waves by coupling to the radial component of the momentum equation. Next, these waves steepen into solitons that accelerate the solar wind to supersonic speed in the radial direction even in a low-beta plasma. The solitary wave phase velocity was found to be slightly above the sound speed in the coronal hole; for example, with the driving Alfven wave amplitude v_d~40 km s(-1) , and plasma beta =5% the soliton phase speed ~ 200 km s(-1) . We investigate the parametric dependence of the soliton wavelength and frequency on the plasma beta , and on the driving Alfven wave amplitude and frequency. More simplified analytical model of the coronal hole leads to the Benjamin-Ono equation that predicts the generation of solitons analytically. The compressive dissipation of solitary waves may contribute significantly to coronal hole heating. In addition, Ohmic heating takes place near the coronal hole boundaries due to phase-mixing of the torsional Alfven waves in the inhomogeneous regions. When solitary waves are present the solar wind fluctuates considerably on long time scales and on small spatial scales in addition to the Alfvenic fluctuations. This is in better qualitative agreement with observations than the thermally driven and WKB Alfven wave solar wind models. Title: Signatures of Global Mode Alfven Resonance Heating in Coronal Loops Authors: Ofman, L.; Davila, J. M.; Shimizu, T. Bibcode: 1996ApJ...459L..39O Altcode: The Yohkoh Soft X-Ray Telescope (SXT) observations of active region coronal loops transient brightening is analyzed, and the scaling of the thermal energy release with loop lengths is found to be Eth ~ L1.60+/-0.09. The numerically determined scaling of the global mode heating rate for the resonant absorption of Alfven waves, H ~ L, is found to agree with the heating rate deduced from the observed thermal energy scaling, provided that the magnetic field scales as B ~ L-0.70+/-0.05 and the waves are driven with a omega -1 spectrum. Previous analytical and numerical studies have shown that the heating due to resonant absorption of Alfven waves is most efficient at the global mode frequency. In agreement with these studies, we suggest that coronal loop transient X-ray brightenings occur when a given length coronal loop is perturbed at its global mode frequency by random footpoint motions, which results in more efficient heating of the loop. Title: X-Ray Pulsar Two-Line Spectra from a Two-Component Accretion Column Authors: Alexander, S. G.; Davila, J.; Dimattio, D. J. Bibcode: 1996ApJ...459..666A Altcode: Several X-ray pulsars exhibit line structure in their spectra that has been interpreted as originating from cyclotron processes in the accreting plasma. A few of these objects also show evidence of a second spectral feature that, traditionally, has been thought to be the second cyclotron harmonic. Detailed calculations of the emitted flux spectra are presented that incorporate a simple two-component model of the accretion cap. The two components are modeled as slabs separated by a shock wave, where the postshock slab is the thermalized high-density and -temperature plasma that creates the radiation via bremsstrahlung processes and the preshock material is represented by a relatively cool, low-density plasma that is moving near the free-fall velocity. Results show that two spectral features are easily produced, one representing the fundamental cyclotron harmonic of the postshock plasma, and another that is a Doppler-shifted line produced by scattering in the preshock plasma. Title: Measurements of Active and Quiet Sun Coronal Plasma Properties with SERTS EUV Spectra Authors: Brosius, J. W.; Davila, J. M.; Thomas, R. J.; Monsignori-Fossi, B. C.; Saba, J. L. R. Bibcode: 1996mpsa.conf..421B Altcode: 1996IAUCo.153..421B No abstract at ADS Title: Solar EUV spectroscopy with serts: measurements of active and quiet Sun properties. Authors: Brosius, J. W.; Davila, J. M.; Thomas, R. J.; Jordan, S. D.; Monsignori-Fossi, B. C. Bibcode: 1996uxsa.conf...83B Altcode: 1996uxsa.coll...83B The Solar EUV Rocket Telescope and Spectrograph (SERTS) was developed by the Laboratory for Astronomy and Solar Physics at NASA/Goddard Space Flight Center. It was successfully flown in 1989, 1991, 1993, and (very recently) 1995, providing spectra and images of a variety of solar features on each occasion. SERTS data have been used to address numerous problems in solar physics, of which the following are discussed below: (1) measurement of coronal temperature and density, (2) derivation of differential emission measure distribution, (3) verification of atomic physics parameters, (4) determination of relative elemental abundances, (5) formation of the He II 304 Å line, (6) mass flows, and (7) coronal magnetography. Title: Nonlinear Excitation of Global Modes and Heating in Randomly Driven Coronal Loops Authors: Ofman, L.; Davila, J. M. Bibcode: 1996ApJ...456L.123O Altcode: We solve the nonlinear three-dimensional MHD equations for fully compressible, low- beta , resistive plasma to model resonant Alfven wave heating of a coronal loop. Alfven waves are driven in the loop by a (pseudo)random time-dependent forcing with a bounded amplitude. We find that global modes are excited and resonantly heat the loop in the nonlinear regime in three dimensions. Resonant heating occurs in several narrow layers accompanied by high velocity and magnetic field shear. The narrow dissipation layers are affected by the self-consistent velocity shear and are carried around by the flow. Consequently, the topology of the perpendicular magnetic field and the ohmic heating regions differs significantly from the linear or single-frequency driver regimes, and the heating is spread more uniformly inside the loop. The heating rate varies significantly on a timescale of one to several global mode periods. We conclude that, in solar active regions, random field-line motions can excite global mode oscillations and resonantly heat the loops with a time-varying heating rate. Title: Alfvén wave heating of coronal holes and the relation to the high-speed solar wind Authors: Ofman, L.; Davila, J. M. Bibcode: 1995JGR...10023413O Altcode: Coronal hole regions are well-known sources of high-speed solar wind; however, to account for the observed properties of the solar wind, a source of energy must be included in addition to heat conduction. Alfvén waves were suggested as the possible source of heating that accelerates the solar wind. We investigate the heating and propagation of the fast and shear Alfvén waves in coronal holes via numerical solution of the time-dependent, linearized, resistive, low-β, two-dimensional MHD equations in slab geometry. The waves are driven at the lower boundary of the coronal hole and propagate into the corona. We find that fast waves are partially reflected at the coronal hole boundary and significant part of the wave energy leaks out of the coronal hole. We compare the calculated wavelengths and the attenuation rate of the fast waves in the leaky waveguide formed by the coronal hole with the analytical ideal MHD solutions for ky=0, where ky is the perpendicular wavenumber, and find an excellent agreement. When ky≠0 the fast waves couple to the shear Alfvén waves and transfer energy across field lines.

Resonance heating layers are found to occur when shear Alfvén waves are driven and a continuous density profile is assumed for the coronal hole. When resonance absorption is considered, the leakage is small compared to the heating rate. The heating is enhanced by phase mixing when coronal hole inhomogeneities (i.e., plumes) are included. We investigate the dependence of the heating rate on the driver frequency and the Lundquist number S and find a good agreement with the analytical S1/3 scaling of the dissipation length. We find that when S=104 the low-frequency Alfvén waves can be a significant source of heating of coronal holes at several solar radii. At larger values of S, nonlinear effects might reduce the effective dissipation length. We discuss the relation of our results to the observed properties of high-speed solar wind and coronal holes. Title: Nonlinear resonant absorption of Alfvén waves in three dimensions, scaling laws, and coronal heating Authors: Ofman, L.; Davila, J. M. Bibcode: 1995JGR...10023427O Altcode: The nonlinear evolution of the resonant absorption of standing and propagating Alfvén waves in an inhomogeneous plasma is studied via solution of the time-dependent, three-dimensional, low-β, resistive MHD equations over a wide parameter range. When the nonlinear effects become important, the velocities at the dissipation layer were found to be lower than the linear scaling of S1/3 would predict, where S is the Lundquist number. Highly sheared velocities that are subject to the Kelvin-Helmholtz-like instability were found at the narrow dissipation layers. Three-dimensional Kelvin-Helmholtz-like vortices appear at and near the dissipation layers and propagate along the slab of plasma when traveling Alfvén wave solution are considered. The narrow resonant heating layers are deformed by the self-consistent shear flow. In the solar active regions where the resonant absorption of Alfvén waves is believed to occur, the instability may lead to turbulent enhancement of the dissipation parameters and account for the observed turbulent velocities inferred from the nonthermal broadening of x-ray and EUV emission lines. The self consistent J×B force changes significantly the density structure of the loop that leads to a shift in the global mode frequency response of the loop and a subsequent drop in the heating rate. In the solar corona the density evolution of the loop is likely to be dominated by evaporation of material from the transition region. Title: Performance comparison of two Wolter type II telescopes in the far ultraviolet Authors: Leviton, Douglas B.; Wright, Geraldine A.; Thomas, Roger J.; Davila, Joseph M.; Epstein, Gabriel L. Bibcode: 1995ApOpt..34.6459L Altcode: Experimental results for image quality and scatter in far-UV light are used to choose between the conventionally polished Solar Extreme-Ultraviolet Rocket Telescope and Spectrograph (SERTS-A) and computer-controlled polished SERTS-C Wolter type II solar rocket telescopes for an extreme-UV flight instrument. In 124-nm light the SERTS-C telescope image had a 0.67-arcsec full width at half-maximum (FWHM), compared with a 1.25-arcsec FWHM for the SERTS-A telescope. In addition SERTS-C had twice the peak irradiance of SERTS-A and an order of magnitude lower near-angle scatter. The inflight performance of the telescopes is consistent with laboratory findings. Title: Reply to “Comment on nonlinear studies of coronal heating by the resonant absorption of Alfvén waves” by J. V. Hollweg Authors: Ofman, L.; Davila, J. M.; Steinolfson, R. S. Bibcode: 1995GeoRL..22.2679O Altcode: No abstract at ADS Title: Heating of coronal holes by the resonant absorption and dissipation of Alfven waves and its relation to solar wind acceleration Authors: Ofman, L.; Davila, J. M. Bibcode: 1995sowi.confQ..66O Altcode: Coronal hole regions are well known sources of high-speed solar wind, however to account for the observed properties of the solar wind a source of momentum and heat must be included. Alfven waves were suggested as the possible source of heating that accelerates the solar wind. We investigate the propagation of the Alfven waves in coronal holes via numerical solution of the linearized 2-D resistive MHD equations in slab geometry. The Alfven waves are driven at the lower boundary of the coronal hole and propagate into the corona. The waves are reflected at the coronal hole boundary and part of the wave energy leaks out of the coronal hole. We compare the calculated wavelengths and the attenuation rate of the fast mode Alfven waves in the leaky waveguide formed by the coronal hole with the analytical ideal MHD solutions. The formation of resonance heating layers is found to occur when shear Alfven waves propagate in an inhomogeneous coronal hole. The heating is enhanced when fast mode waves couple to the shear Alfven waves. The narrow heating layers are formed near the location of the ideal resonance, which might occur near the coronal hole boundary for a nearly constant density coronal hole, surrounded by a higher density plasma. We investigate the dependence of the heating on the driver frequency, the Lundquist number, and on the heliocentric distance. and find that the low frequency Alfven waves can be an efficient source of heating at large distances from the Sun. We discuss the relation of our results to the observed properties of high-speed solar wind and coronal holes. Title: Coronal Heating by the Resonant Absorption of Alfven Waves: Wavenumber Scaling Laws Authors: Ofman, L.; Davila, J. M.; Steinolfson, R. S. Bibcode: 1995ApJ...444..471O Altcode: The importance of global modes in coronal loop heating is well established. In the present work the scaling of the global-mode resonant heating rate with the perturbation wavenumbers is studied with the numerical solution of the linearized time-dependent MHD equations for a full compressible, low-beta, resistive plasma using an implicit integration scheme. The numerical simulations demonstrate that the dissipation on inhomogeneities in the background Alfven speed occurs in narrow resonant layer with the highest heating rate at the global-mode frequency. The global-mode heating rate H r was found to scale as H (Sub r) approximately k y 1.03 when k z = 0.1, and as H r approximately k y -1.93 when k z = 0.75, where k y and k z are the wavenumbers in the perpendicular and parallel to the magnetic field directions, respectively, while the dependence of H r on k z is more complex. The quality factor Q of the MHD resonance cavity scales as Q approximately k y -1.8 for k z = 0.75 and as Q approximately k y -1.46 for k z = 0.1. The numerically determined heating rate scaling, the global-mode fequency, and the quality factor are in good agreement with the analytical linear theory. The magnitude of the perturbed velocities was found to decrease with k y. Assuming typical coronal loop parameters (B 0 = 100-200 G, upsilon A = 2000-4000 km/s), the Alfven waves can supply the required heating to a low-Q loops. Title: Heating of Coronal Holes by the Resonant Absorption and Dissipation of Alfvén Waves Authors: Ofman, L.; Davila, J. M. Bibcode: 1995SPD....26..907O Altcode: 1995BAAS...27..974O No abstract at ADS Title: Measurements of Active and Quiet Sun Coronal Plasma Properties with SERTS EUV Spectra Authors: Brosius, J. W.; Davila, J. M.; Thomas, R. J.; Monsignori-Fossi, B. C. Bibcode: 1995SPD....26..607B Altcode: 1995BAAS...27..962B No abstract at ADS Title: Are Spicules Evidence for Small-scale Motions that Redistribute HE II Ions to Produce Enhanced 304A Line Emission? Authors: Jordan, S. D.; Davila, J. M.; Thomas, R. J.; Garcia, A. Bibcode: 1995SPD....26..508J Altcode: 1995BAAS...27..958J No abstract at ADS Title: Nonlinear studies of coronal heating by the resonant absorption of Alfvén waves Authors: Ofman, L.; Davila, J. M.; Steinolfson, R. S. Bibcode: 1994GeoRL..21.2259O Altcode: The first nonlinear study of the instability of the resonant absorption is presented in this paper. The nonlinear evolution of the resonant absorption of Alfvén waves in an inhomogeneous plasma is studied via solution of the time-dependent 3-D, low-β, resistive MHD equations. Highly sheared velocities that are subject to the Kelvin-Helmholtz like instability are found at the narrow dissipation layers. Three dimensional Kelvin-Helmholtz like vortices appear at and near the dissipation layers and propagate along the slab of plasma. The narrow resonant heating layers are deformed by the self-consistent shear flow. In the solar active regions where the resonant absorption of Alfvén waves is believed to occur the instability may lead to turbulent enhancement of the dissipation parameters and account for the observed turbulent velocities inferred from the non-thermal broadening of x-ray and EUV emission lines. Title: Solar Coronal Temperature Diagnostics Using Emission Lines from Multiple Stages of Ionization of Iron Authors: Brosius, Jeffrey W.; Davila, Joseph M.; Thomas, Roger J.; Thompson, William T. Bibcode: 1994ApJ...425..343B Altcode: We obtained spatially resolved extreme-ultraviolet (EUV) spectra of AR 6615 on 1991 May 7 with NASA/ Goddard Space Flight Center's Solar EUV Rocket Telescope and Spectrograph (SERTS). Included are emission lines from four different stages of ionization of iron: Fe(+15) lambda 335 A, Fe(+14) lambda 327 A, Fe(+13) lambda 334 A, and Fe(+12) lambda 348 A. Using intensity ratios from among these lines, we have calculated the active region coronal temperature along the Solar Extreme Ultraviolet Telescope and Spectrograph (SERTS) slit. Temperatures derived from line ratios which incorporate adjacent stages of ionization are most sensitive to measurement uncertainties and yield the largest scatter. Temperatures derived from line ratios which incorporate nonadjacent stages of ionization are less sensitive to measurement uncertainties and yield little scatter. The active region temperature derived from these latter ratios has an average value of 2.54 x 106 K, with a standard deviation approximately 0.12 x 106 K, and shows no significant variation with position along the slit. Title: Solar Tomography Authors: Davila, Joseph M. Bibcode: 1994ApJ...423..871D Altcode: Tomographic imaging has provided the medical profession with unprecedented three-dimensional views of the internal structure of the human body. Similar techniques can provide solar physicists with an equally spectacular view of the three-dimensional structure of the solar corona, providing a new tool for addressing the problems of coronal structure, energy balance, and evolution. For the reconstruction process, images of the solar corona observed from different angular positions within the ecliptic are needed, and these are not yet available. The purpose is to demonstrate the utility and the practicality of solar tomography with a series of computer simulations of the process, while exploring the sensitivity of the results to some of the parameters of the observing process, e.g., the number of observations, angular spacing, and signal to noise. The results show that tomography can be a powerful technique for determining the three-dimensional nature of active region magnetic fields, coronal loops, helmet streamers, coronal holes, and other structures in the corona. Title: Coronal Heating by the Resonant Absorption of Alfven Waves Authors: Ofman, L.; Davila, J. M.; Steinolfson, R. S. Bibcode: 1994scs..conf..473O Altcode: 1994IAUCo.144..473O Nonlinear evolution and stability of the resonant absorption layer is considered by solving the time-dependent 3D, low-β, resistive MHD equations with the Lax-Wendroff explicit method. The narrow resonant heating layers are deformed by the self-consistent shear flow. When the driver amplitude is small compared to the average Alfvén speed the dissipation layer appears to be stable and the driver-period-averaged ohmic heating rate saturates at a slightly higher than the linear rate. When the driver amplitude is large (Fd ≍ 1) the resonant heating may become unstable. Title: Coronal Heating by the Resonant Absorption of Alfven Waves: The Effect of Viscous Stress Tensor Authors: Ofman, L.; Davila, J. M.; Steinolfson, R. S. Bibcode: 1994ApJ...421..360O Altcode: The time-dependent linearized magnetohydrodynamics (MHD) equations for a fully compressible, low-beta, viscoresistive plasma are solved numerically using an implicit integration scheme. The full viscosity stress tensor (Braginskii 1965) is included with the five parameters etai i = 0 to 4. In agreement with previous studies, the numerical simulations demonstrate that the dissipation on inhomogeneities in the background Alfven speed occurs in a narrow resonant layer. For an active region in the solar corona the values of etai are etao = 0.65 g/cm/s, eta1 = 3.7 x 10-12 g/cm/s, eta2 = 4 eta1, eta3 = 1.4 x 10-6 g/cm/s, eta4 = 2 eta3, with n = 1010/cu cm, T = 2 x 106 K, and B = 100 G. When the Lundquist number S = 104 and R1 much greater than S (where R1 is the dimensionless shear viscous number) the width of the resistive dissipation layer dr is 0.22a (where a is the density gradient length scale) and dr approximately S-1/3. When S much greater than R1 the shear viscous dissipation layer width dr scales as R1-1/3. The shear viscous and the resistive dissipation occurs in an overlapping narrow region, and the total heating rate is independent of the value of the dissipation parameters in agreement with previous studies. Consequently, the maximum values of the perpendicular velocity and perpendicular magnetic field scale as R1-1/3. It is evident from the simulations that for solar parameters the heating due to the compressive viscosity (R0 = 560) is negligible compared to the resistive and the shear viscous (R1) dissipation and it occurs in a broad layer of order a in width. In the solar corona with S approximately equals 104 and R1 approximately equals 1014 (as calculated from the Braginskii expressions), the shear viscous resonant heating is of comparable magnitude to the resistive resonant heating. Title: The Effects of Kelvin-Helmholtz Instability on Resonance Absorption Layers in Coronal Loops Authors: Karpen, Judith T.; Dahlburg, Russell B.; Davila, Joseph M. Bibcode: 1994ApJ...421..372K Altcode: One of the long-standing uncertainties in the wave-resonance theory of coronal heating is the stability of the resonance layer. The wave motions in the resonance layer produce highly localized shear flows which vary sinusoidally in time with the resonance period. This configuration is potentially susceptible to the Kelvin-Helmholtz instability (KHI), which can enhance small-scale structure and turbulent broadening of shear layers on relatively rapid ideal timescales. We have investigated numerically the response of a characteristic velocity profile, derived from resonance absorption models, to finite fluid perturbations comparable to photospheric fluctuations. We find that the KHI primarily should affect long (approximately greater than 6 x 104 km) loops where higher velocity flows (M approximately greater than 0.2) exist in resonance layers of order 100 km wide. There, the Kelvin-Helmholtz growth time is comparable to or less than the resonance quarter-period, and the potentially stabilizing magnetic effects are not felt until the instability is well past the linear growth stage. Not only is the resonance layer broadened by the KHI, but also the convective energy transport out of the resonance layer is increased, thus adding to the efficiency of the wave-resonance heating process. In shorter loops, e.g., those in bright points and compact flares, the stabilization due to the magnetic field and the high resonance frequency inhibit the growth of the Kelvin-Helmholtz instability beyond a minimal level. Title: Potential IR Observations of the Solar Corona Authors: Kumar, C. K.; Davila, J. Bibcode: 1994IAUS..154...81K Altcode: No abstract at ADS Title: Solar Tomography Authors: Davila, J. M. Bibcode: 1993AAS...183.5907D Altcode: 1993BAAS...25.1387D Images obtained by observing the solar corona from a single spacecraft typically measure the line-of-sight integral of the volumetric emissivity through the source. The resulting two-dimensional observations have an unavoidable ambiguity along the line of sight that can be removed only by making assumptions about the three dimensional nature of the emission. These ambiguities can be removed by observing the Sun from different vantage points, at the same time, i.e. solar tomography. The basic concept of tomographic is fairly simple. For an optically thin emission source, like the solar corona, each pixel in an image represents the line of sight integration of the volumetric emissivity of the plasma at the wavelength of observation. By obtaining several of these observations, from various angles, the underlying three dimensional structure of the emission can be deduced. This principle has been used extensively in the Medical community for the imaging of internal structure of the body with such techniques as Computer Aided Tomography (CAT) scanners and Magnetic Resonance Imaging (MRI). The purpose of this paper is to take an intial look at the following two questions: (1) Is tomography feasible with a few spacecraft?; and (2) What scientific objectives can be addressed? Title: A High-Resolution Solar Spectrum in the EUVE Bandpass Authors: Thomas, Roger J.; Davila, Joseph M. Bibcode: 1993AAS...183.0804T Altcode: 1993BAAS...25.1301T The Solar EUV Rocket Telescope and Spectrograph (SERTS) obtains imaged spectra of solar features with resolution around 0.04 Angstroms and high sensitivity. Its spectral range of 170 -- 450 Angstroms overlaps large portions of the Medium Wavelength and Long Wavelength Spectrographs on EUVE, and so may provide help in interpreting the lower resolution EUVE spectra of late-type stellar sources. As an example, we compare SERTS observations averaged over a typical solar active region with EUVE calibration spectra of Capella, a G6 + G2 binary. The Capella spectra include prominent spectral features at 256.5, 284.7, 304.2, 335.4, and 360.3 Angstroms. The SERTS spectrum indicates that, although these features are generally dominated by a single emission line, they may also be contaminated to some degree by blends of other lines at the resolutions of the EUVE spectrographs, which are approximately 1.0 and 2.0 Angstroms. This high-resolution solar active region spectrum from SERTS is now available electronically by request to thomas@jet.gsfc.nasa.gov, as are emission line catalogs derived from it. This work was supported under NASA RTOP 170-38-52. Title: Nonlinear Evolution of Coronal Heating by the Resonant Absorption of Alfven Waves Authors: Ofman, L.; Davila, J. M.; Steinolfson, R. S. Bibcode: 1993AAS...183.5904O Altcode: 1993BAAS...25.1386O The nonlinear 3-D MHD equations for a fully compressible, low-beta, visco-resistive plasma are solved numerically using the Lax-Wendroff integration scheme (the explicit integration scheme was found to converge considerably faster in terms of physical time per CPU time than the Alternating Direction Implicit method). The calculations are initiated with the solutions of the linearized version of the MHD equations (Ofman, Davila, and Steinolfson 1994, Ap.J., in press), with inhomogeneous background density, and a constant magnetic field. The numerical simulations demonstrate that the narrow dissipation layer is affected by the self-consistent velocity shear: i.e., the regions of high ohmic heating are carried around by the flow. Consequently, the topology of the perpendicular magnetic field and the ohmic heating regions differs significantly from the linear case. Additional harmonics of the driver frequency appear in the temporal oscillations with the dominant frequency of double the driver frequency. When the Lundquist number is S=10(3) the average width of the resistive dissipation layer is 0.4a (where a is the density gradient length scale) and consistent with the linear results. When the driver amplitude is small compared to the average Alfven speed the dissipation layer appears to be stable and the ohmic heating rate is enhanced by about 15% over the linear heating rate. When the driver amplitude is comparable to the average Alfven speed the nonlinear effects dominate the evolution and the resonant heating layer may become unstable. A parametric study of the instability is presented. The effect of the self-consistent velocity on the instability is considered by generalizing the linear theory (Davila 1987) to include shear flow and solving the linearized dispersion relation of the resonant absorption with the background shear flow. (*) NRC-NAS Resident Research Associate. Title: Heating Constraints on the Solar Corona Determined from SERTS Observations Authors: Falconer, D. A.; Davila, J. M.; Thomas, R. J.; Thompson, W. T. Bibcode: 1993AAS...183.5905F Altcode: 1993BAAS...25.1386F EUV emission above the quiet solar limb up to 1.2Rsun was studied using observations made from two different flights of the Goddard Solar EUV Rocket Telescope and Spectrograph (SERTS) covering three different spatial locations. The spectral line intensities from a number of EUV spectral lines as a function of height were analyzed. Ratio of iron line intensities from Fe XIII, Fe XIV, Fe XV and Fe XVI were used to determine the electron temperature. The emission measure was determined from the iron line intensities and the electron temperature. Since in all three cases the line ratio temperature increased with height, a source of heating is required at some location above the maximum observed height, which was 1.15Rsun for two locations and 1.2Rsun for the third location. The maximum divergence of heat flux was determined from the variation of temperature versus radius. The total radiatiative power was obtained from the emission measure and temperature. By comparing the divergence of heat flux and the total radiatiative power, heating was also shown to be necessary for two of the three cases throughout the region below 1.15Rsun. (*) ARC Title: Coronal Heating by the Resonant Absorption of Alfven Waves: Importance of the Global Mode and Scaling Laws Authors: Steinolfson, Richard S.; Davila, Joseph M. Bibcode: 1993ApJ...415..354S Altcode: Numerical simulations of the MHD equations for a fully compressible, low-beta, resistive plasma are used to study the resonance absorption process for the heating of coronal active region loops. Comparisons with more approximate analytic models show that the major predictions of the analytic theories are, to a large extent, confirmed by the numerical computations. The simulations demonstrate that the dissipation occurs primarily in a thin resonance layer. Some of the analytically predicted features verified by the simulations are (a) the position of the resonance layer within the initial inhomogeneity; (b) the importance of the global mode for a large range of loop densities; (c) the dependence of the resonance layer thickness and the steady-state heating rate on the dissipation coefficient; and (d) the time required for the resonance layer to form. In contrast with some previous analytic and simulation results, the time for the loop to reach a steady state is found to be the phase-mixing time rather than a dissipation time. This disagreement is shown to result from neglect of the existence of the global mode in some of the earlier analyses. The resonant absorption process is also shown to behave similar to a classical driven harmonic oscillator. Title: Simultaneous Observations of Solar Plage with the Solar Extreme Ultraviolet Rocket Telescope and Spectrograph (SERTS), the VLA, and the Kitt Peak Magnetograph Authors: Brosius, Jeffrey W.; Davila, Joseph M.; Thompson, William T.; Thomas, Roger J.; Holman, Gordon D.; Gopalswamy, N.; White, Stephen M.; Kundu, Mukul R.; Jones, Harrison P. Bibcode: 1993ApJ...411..410B Altcode: We obtained simultaneous images of solar plage on 1991, May 7 with SERTS, the VLA,4 and the NASA/National Solar Observatory spectromagnetograph at the NSO/Kitt Peak Vacuum Telescope. Using intensity ratios of Fe XVI to Fe XV emission lines, we find that the coronal plasma temperature is (2.3-2.9) x 10 exp 6 K throughout the region. The column emission measure ranges from 2.5 x 10 exp 27 to l.3 x 10 exp 28 cm exp -5. The calculated structure and intensity of the 20 cm wavelength thermal bremsstrahlung emission from the hot plasma observed by SERTS is quite similar to the observed structure and intensity of the 20 cm microwave emission observed by the VLA. Using the Meyer (1991, 1992) revised coronal iron abundance, we find no evidence either for cool absorbing plasma or for contributions from thermal gyroemission. Using the observed microwave polarization and the SERTS plasma parameters, we calculate a map of the coronal longitudinal magnetic field. The resulting values, about 30-60 G, are comparable to extrapolated values of the potential field at heights of 5000 and 10,000 km. Title: Tomography of the Solar Corona Authors: Davila, J. M. Bibcode: 1993BAAS...25.1191D Altcode: No abstract at ADS Title: Solar Coronal Plasma and Magnetic Field Diagnostics Using SERTS and Coordinated VLA Observations Authors: Brosius, J. W.; Davila, J. M.; Thompson, W. T.; Thomas, R. J.; Holman, G. D.; Gopalswamy, N.; White, S. M.; Kundu, M. R.; Jones, H. P. Bibcode: 1993BAAS...25.1224B Altcode: No abstract at ADS Title: Properties of the Quiet Solar Corona up to 1. 2 Solar Radii Derived from SERTS Observations Authors: Falconer, D. A.; Davila, J. M.; Thomas, R. J. Bibcode: 1993BAAS...25.1200F Altcode: No abstract at ADS Title: Flows Observed in the Solar Corona with SERTS Authors: Davila, J. M. Bibcode: 1993BAAS...25.1210D Altcode: No abstract at ADS Title: Coronal Heating by the Resonant Absorption of Alfven Waves: The Effects of Viscous Stress Tensor Authors: Ofman, L.; Davila, J. M.; Steinolfson, R. S. Bibcode: 1993BAAS...25.1202O Altcode: No abstract at ADS Title: Analysis of EUV, Microwave and Magnetic Field Observations of Solar Plage Authors: Brosius, J. W.; Davila, J. M.; Jones, H. P.; Thompson, W. T.; Thomas, R. J.; Holman, G. D.; White, S. W.; Gopalswamy, N.; Kundu, M. R. Bibcode: 1993ASPC...46..291B Altcode: 1993mvfs.conf..291B; 1993IAUCo.141..291B No abstract at ADS Title: First flight of an extreme-ultraviolet spectrometer with a multilayer grating. Authors: Davila, J. M.; Thomas, R. J.; Thompson, W. T.; Keski-Kuha, R. A. M.; Neupert, W. M. Bibcode: 1993uxrs.conf..301D Altcode: 1993uxsa.conf..301D The authors report the first space flight of an extreme-ultraviolet (EUV) spectrograph incorporating a multilayer coated normal incidence grating in the Solar Extreme-ultraviolet Rocket Telescope and Spectrograph (SERTS). Pre-flight performance evaluation showed that the application of a 10-layer Ir/Si multilayer coating to the 3600 l/mm, blazed, toroidal replica grating produced a factor of nine enhancement in peak efficiency near the design wavelength around 30 nm in first order over the standard gold coating used in earlier flights. In addition, a spectral resolution of better than 5000 was maintained. This technology, now proven in space flight, is applicable to most normal incidence spectrographs used for astronomical observation in the ultraviolet, far and extreme ultraviolet and soft X-ray regions of the spectrum. Title: Underneath coronal loops: MSDP observations coordinated with SERTS 4 and NIXT flights. Authors: Schmieder, B.; Mein, N.; Golub, L.; Davila, J. M.; Thomas, R.; Brosius, J. Bibcode: 1992ESASP.348..257S Altcode: 1992cscl.work..257S Ground-based coordinated observations with the multichannel subtractive double pass spectrograph (MSDP) allowed to portray the chromospheric intensity and velocity fields below coronal structures during recent launchs of sounding rockets. During SERTS 4 observations (May 7, 1991), two different active regions presenting flare and filament have been coaligned with UV structures. In July 11, 1991 (eclipse day) large Hα ejection material in AR 6713 was detected during the NIXT flight. Preliminary results are displayed. Title: The Effects of Kelvin-Helmholtz Instability on Resonance Absorption Layers in Coronal Loops Authors: Karpen, J. T.; Dahlberg, R. B.; Davila, J. M. Bibcode: 1992AAS...180.5507K Altcode: 1992BAAS...24..820K No abstract at ADS Title: Analysis of EUV, Microwave, and Magnetic Field Observations of a Solar Active Region Authors: Brosius, J. W.; Davila, J. M.; Jones, H. P.; Thompson, W. T.; White, S. M.; Gopalswamy, N.; Kundu, M. R. Bibcode: 1992AAS...180.4002B Altcode: 1992BAAS...24R.792B No abstract at ADS Title: Results of the Fourth Flight of SERTS Authors: Davila, J. M.; Thomas, R. J.; Thompson, W. T. Bibcode: 1992AAS...180.4001D Altcode: 1992BAAS...24..792D No abstract at ADS Title: The Coronal Density and Temperature for 1.05 <R < 1.5 Derived from SERTS Observation Authors: Falconer, D. A.; Davila, J. M.; Thomas, R. J. Bibcode: 1992AAS...180.4003F Altcode: 1992BAAS...24..792F No abstract at ADS Title: A Rotating Tomographic Imager for Solar Extreme-Ultraviolet/Soft X-Ray Emission Authors: Davila, Joseph M.; Thompson, W. T. Bibcode: 1992ApJ...389L..91D Altcode: A concept is presented for a high-resolution EUV/soft-X-ray imager that has much in common with the medical imaging procedure of tomography. The resulting instrument is compatible with a simpler, less costly spin-axis-stabilized spacecraft. To demonstrate the fidelity of the reconstruction procedure, the observation and reconstruction is simulated to compare the results with the original image. Title: Rocket flight of a multilayer coated high-density EUV toroidal grating Authors: Keski-Kuha, Ritva A. M.; Thomas, Roger J.; Davila, Joseph M. Bibcode: 1992SPIE.1546..614K Altcode: A multilayer coated high density toroidal grating was flown on a sounding rocket experiment in the Solar EUV Rocket Telescope and Spectrograph (SERTS) instrument. To our knowledge this is the first space flight of a multilayer coated grating. Pre-flight performance evaluation showed that the application of a 10-layer Ir/Si multilayer coating to the 3600 l/mm blazed toroidal replica grating produced a factor of 9 enhancement in peak efficiency near the design wavelength around 30 nm in first order over the standard gold coating, with a measured EUV efficiency that peaked at 3.3 percent. In addition, the grating's spectral resolution of better than 5000 was maintained. The region of enhanced grating efficiency due to the multilayer coating is clearly evident in the flight data. Within the bandpass of the multilayer coating, the recorded film densities were roughly equivalent to those obtained with a factor of six longer exposure on the previous flight of the SERTS instrument. Title: Magnetoacoustic Heating of the Solar Chromosphere Authors: Davila, Joseph M.; Chitre, S. M. Bibcode: 1991ApJ...381L..31D Altcode: Long-period acoustic waves generated in the solar convection zone can propagate radially outward through the overlying atmosphere and get resonantly absorbed in the magnetic arches of the low-lying chromospheric canopy. The resulting Poynting and acoustic flux that enters the magnetic canopy in the network regions is demonstrated to be adequate to account for the observed chromospheric emission. Title: Simultaneous EUV, Microwave, and Magnetic Field Observations of Solar Active Regions Authors: Brosius, J. W.; Davila, J. M.; Thompson, W. T.; Gopalswamy, N.; White, S. M.; Jones, H. P.; Metcalf, T. R. Bibcode: 1991BAAS...23.1388B Altcode: No abstract at ADS Title: Recent Observations of the Solar Corona with SERTS, an EUV Multilayer Spectrograph Authors: Davila, J. M.; Thomas, R. J.; Thompson, W. T.; Keski-Kuha, R. A. M.; Neupert, W. M. Bibcode: 1991BAAS...23.1387D Altcode: No abstract at ADS Title: The Resonant Absorption of p-Modes by Sunspots with Twisted Magnetic Fields Authors: Chitre, S. M.; Davila, Joseph M. Bibcode: 1991ApJ...371..785C Altcode: A simplified inhomogeneous sunspot model with an axial current (twisted magnetic field) is considered. The absorption of incoming acoustic modes in a narrow resonance layer inside the sunspot flux tube is investigated, and the energy loss is estimated. For nonaxisymmetric modes the results are consistent with previous calculations. However, contrary to previous work, it is demonstrated that the existence of an azimuthal component of the magnetic field can lead to significant absorption of even the axisymmetric modes. If the absorption rate calculated in this paper is used in conjunction with the observed wavelength dependence of the absorption coefficient, it is found that the sunspot flux tube must have significant twist in the subsurface layers. Furthermore, the presence of twist in the magnetic field leads to a natural explanation for the observed dependence on m, the azimuthal wave mode number, and the magnitude of the absorption coefficient can be accounted for in a self-consistent way. Title: Solar Tomography: Deducing the Three-dimensional Structure of the Corona from Stereoscopic Images of Optically Thin Line Emission Authors: Davila, J. M. Bibcode: 1991BAAS...23.1063D Altcode: No abstract at ADS Title: Magnetoacoustic Heating of the Solar Chromosphere (With 1 Figure) Authors: Chitre, S. M.; Davila, J. M. Bibcode: 1991mcch.conf..402C Altcode: No abstract at ADS Title: Resonance Absorption Heating (With 5 Figures) Authors: Davila, J. M. Bibcode: 1991mcch.conf..464D Altcode: No abstract at ADS Title: Sunspot Seismology Theory Authors: Davila, Joseph M. Bibcode: 1990IAUS..142..149D Altcode: Physical mechanisms proposed to explain the absorption of significant p-mode wave power by sunspots are reviewed, and their viability in view of the current knowledge of the scattering process is discussed. It is concluded that there is no satisfactory theoretical model for the absorption of p-modes by sunspots available at present. It is argued that the resonance absorption model is able to obtain the large absorption coefficients observed for nonaxisymmetric perturbations. For axisymmetric perturbations, departures from perfect cylindrical symmetry or the inclusion of a slight twist in the sunspot flux tube may be able to resolve the problem with the absorption of m = 0 wave modes. Other dissipative models, which do not incorporate the background gradient effects inherent in the resonance absorption mechanism, require inconveniently large dissipation coefficients within the sunspot. Title: Resonant Absorption of P-Modes by Sunspots Authors: Chitre, S. M.; Davila, Joseph M. Bibcode: 1990IAUS..142..187C Altcode: Explanations for the observed p-mode absorption in sunspots are examined. It is demonstrated that any dissipative process like radiative, viscous, or resistive dissipation leads to the resonant absorption of acoustic waves incident on the sunspot tube, and that the resultant heating rate can be shown to be consistent with the observed absorption of the p-mode power impinging on an isolated inhomogeneously structured sunspot. Title: The Scattering of Solar P-Modes by Sunspots Authors: Davila, J.; Jensen, K. Bibcode: 1989BAAS...21.1110D Altcode: No abstract at ADS Title: Sunspot Seismology Authors: Chitre, S. M.; Davila, J. M. Bibcode: 1989BAAS...21.1110C Altcode: No abstract at ADS Title: A Theory for the Scattering of Solar P-Modes by Sunspots Authors: Jensen, K.; Davila, J. Bibcode: 1989BAAS...21..837J Altcode: No abstract at ADS Title: The Accretion of Interplanetary Dust by AP and AM Stars Authors: Kumar, C. Krishna; Davila, Joseph M.; Rajan, R. Sundar Bibcode: 1989ApJ...337..414K Altcode: Accretion of interplanetary dust and comets by A-type stars is investigated to see whether this process can explain the overabundances of heavy elements in Ap and Am stars. The dust particles spiral in by the Poynting-Robertson effect and evaporate above the star. This process is evaluated by considering the evolution of silicate and graphite particles in the radiation field of Alpha Leo (B7 V). It is found that graphite particles evaporate above 20 stellar radii and silicate dust grains above 50 stellar radii. The evaporated atoms will be quickly ionized. In the case of Am stars the ions will wander off and not reach the photosphere, but in the case of Ap stars they can be trapped by the magnetic field of the star and reach the surface. The magnetosphere of a typical Ap star is modeled, and the fate of the ions is studied. The efficiency of accretion from the magnetosphere is sensitive to the presence of any plasma in the magnetosphere. The comet impact process is found capable of producing the abundance anomalies in Ap as well as Am stars, assuming that the comet impact rate is 0.03/yr, nearly the same as in the solar system. Title: A Theory for the Radiation of Magnetohydrodynamic Surface Waves and Body Waves into the Solar Corona Authors: Davila, Joseph M. Bibcode: 1988ApJ...332.1076D Altcode: The Green's function for the slab coronal hole is obtained explicitly. The Fourier integral representation for the radiated field inside and outside the coronal hole waveguide is obtained. The radiated field outside the coronal hole is calculated using the method of steepest descents. It is shown that the radiated field can be written as the sum of two contributions: (1) a contribution from the integral along the steepest descent path and (2) a contribution from all the poles of the integrand between the path of the original integral and the steepest descent path. The free oscillations of the waveguide can be associated with the pole contributions in the steepest descent representation for the Green's function. These pole contributions are essentially generalized surface waves with a maximum amplitude near the interface which separates the plasma inside the coronal hole from the surrounding background corona. The path contribution to the integral is essentially the power radiated in body waves. Title: Guided Waves in Diverging Coronal Hole Waveguides Authors: Davila, J. M. Bibcode: 1988BAAS...20..704D Altcode: No abstract at ADS Title: The heating of coronal loops by MHD waves. Authors: Davila, Joseph M. Bibcode: 1988sscd.conf...97D Altcode: The purpose of this paper is to discuss some of the important developments of the last few years and to illustrate the basic physics of the resonant absorption process by considering dissipation in a simple coronal loop model. It is concluded that resonance absorption is a viable mechanism for the heating of solar active region coronal loops. Title: Resonance Absorption Heating in the Solar Corona Authors: Davila, Joseph M.; Warnock, A., III Bibcode: 1987BAAS...19..937D Altcode: No abstract at ADS Title: Heating of the Solar Corona by the Resonant Absorption of Alfven Waves Authors: Davila, Joseph M. Bibcode: 1987ApJ...317..514D Altcode: An improved method for calculating the resonance absorption heating rate is discussed and the results are compared with observations in the solar corona. To accomplish this, the wave equation for a dissipative, compressible plasma is derived from the linearized magnetohydrodynamic equations for a plasma with transverse Alfven speed gradients. For parameters representative of the solar corona, it is found that a two-scale description of the wave motion is appropriate. The large-scale motion, which can be approximated as nearly ideal, has a scale which is on the order of the width of the loop. The small-scale wave, however, has a transverse scale much smaller than the width of the loop, with a width of about 0.3-250 km, and is highly dissipative. These two wave motions are coupled in a narrow resonance region in the loop where the global wave frequency equals the local Alfven wave frequency. Formally, this coupling comes about from using the method of matched asymptotic expansions to match the inner and outer (small and large scale) solutions. The resultant heating rate can be calculated from either of these solutions. A formula derived using the outer (ideal) solution is presented, and shown to be consistent with observations of heating and line broadening in the solar corona. Title: The Acceleration of Winds by MHD Waves in Open Magnetic Structures Authors: Davila, J. M. Bibcode: 1987sowi.conf..107D Altcode: No abstract at ADS Title: Heating of the solar corona by the resonant absorption of Alfvén waves. Authors: Davila, Joseph M. Bibcode: 1986NASCP2442..445D Altcode: 1986copp.nasa..445D An improved method for calculating the resonance absorption heating rate is discussed and the results are compared with observations in the solar corona. The primary conclusion to be drawn from these calculations is that to the level of the approximation adopted, the observations of the heating rate and nonthermal line broadening in the solar corona are consistent with heating by the resonance absorption mechanism. Title: Heating the Solar Corona by the Resonant Absorption of MHD Waves Authors: Davila, J. M. Bibcode: 1986BAAS...18..677D Altcode: No abstract at ADS Title: MHD Wave-Driven Winds from Open Magnetic Structures Authors: Davila, Joseph M. Bibcode: 1986LNP...254..463D Altcode: 1986csss....4..463D No abstract at ADS Title: A leaky magnetohydrodynamic waveguide model for the acceleration of high-speed solar wind streams in coronal holes Authors: Davila, J. M. Bibcode: 1985ApJ...291..328D Altcode: It is well established observationally that high-speed solar wind streams originate in coronal hole regions in the solar corona. One suggested source for the additional momentum of these streams is "wave pressure" generated by magnetohydrodynamic (MHD) waves. In the paper the effect of coronal hole magnetic structure on the propagation of MHD waves of all periods is considered. It is found that the coronal hole structure acts as a "leaky" MHD waveguide, i.e., wave flux which enters at the base of the coronal hole is only weakly guided by the coronal hole structure. The force on the coronal hole plasma due to the propagation of the leaky wave modes is calculated. It is found that the net force consists of two terms: (1) magnetic wave pressure and (2) magnetic wave tension. The calculations imply that the coupling of the solar wind plasma to the turbulence in the photosphere may not be as efficient as previous theories of wave propagation in the corona have indicated. Title: MHD Flux Leakage from a Turbulently Driven Coronal Hole Authors: Davila, Joseph M. Bibcode: 1985BAAS...17..637D Altcode: No abstract at ADS Title: A leaky waveguide model for MHD wave driven winds from coronal holes. Authors: Davila, J. M. Bibcode: 1985NASCP2358..183D Altcode: 1985onhm.rept..183D High speed solar wind streams are now known to originate in discrete open field magnetic structures within the solar corona called coronal holes. The simple model presented in this paper demonstrates that coronal holes can act as waveguides for MHD waves. These waves serve as a source of additional acceleration for the solar wind. Title: The interplanetary scattering mean free path - Collisionless wave-damping effects Authors: Davila, J. M.; Scott, J. S. Bibcode: 1984ApJ...285..400D Altcode: The role of dissipation in the scattering of charged particles in the interplanetary medium (IPM) is analyzed to obtain a model for the interplanetary magnetic turbulence spectrum that yields particle free paths (PEP) which agree with observational data. The scattering processes are attributed to waves with small wavelengths intersected by particles with zero pitch angles. The waves, being strongly damped by collisionless cyclotron damping in the ambient thermal plasma, produce reduced scattering and longer MFPs. The model, which includes the damping factor, was used to generate proton propagation maps at kinetic energy levels of under, over, and within the 5 MeV-2 GeV range. The results, when compared with observational data, displayed good agreement. The same held true for the MFP propagation of energetic electrons. Title: Coronal Holes: A Driven MHD Waveguide Model Authors: Davila, J. M. Bibcode: 1984BAAS...16..928D Altcode: No abstract at ADS Title: The scattering of energetic particles by waves in a finite beta plasma Authors: Davila, J. M.; Scott, J. S. Bibcode: 1984ApJ...280..334D Altcode: Solutions to the dispersion relation for waves propagating parallel to the ambient magnetic field in a plasma of arbitrary β are obtained, where β is the ratio of the thermal pressure to the magnetic pressure. The results of previous authors for wave frequencies, ω, much less than the ion cyclotron frequency, Ωi, are extended to include all frequencies less than the electron cyclotron frequency, Ωe. It is found that the cyclotron turnovers, which occur at Ωei) for the right-hand (left-hand) circularly polarized waves in a cold plasma, occur at significantly lower frequencies in a finite β plasma. The precise limitations of the "high β" approximation are established and details of wave propagation in plasmas with intermediate values of β are examined. Title: Coronal Holes: Leaky MHD Waveguides Authors: Davila, J. M. Bibcode: 1984BAAS...16..452D Altcode: No abstract at ADS Title: Wave Propagation in Magnetic Coronal Loops Authors: Davila, J. M. Bibcode: 1983BAAS...15R.700D Altcode: No abstract at ADS Title: Resolution of the Solar Cosmic Ray Mean Free Path Controversy Authors: Davila, J. M.; Scott, J. S. Bibcode: 1982BAAS...14..977D Altcode: No abstract at ADS Title: The Propagation of Energetic Particles in Finite Temperature Astrophysical Plasmas. Authors: Davila, Joseph Michael Bibcode: 1982PhDT........24D Altcode: Solutions to the dispersion relation for waves propagating parallel to the static magnetic field in a plasma of arbitrary (beta) are obtained. ((beta) is the ratio of thermal to magnetic pressure.) Resonant scattering by these waves is evaluated. It is found that the magnetostatic approximation, used extensively in the past, breaks down for particles with pitch angles near 90(DEGREES), and one must consider the more complicated process of particle scattering in electromagnetic turbulence. Many aspects of particle propagation in a finite temperature plasma can be discussed without assuming magnetostatic turbulence. This is accomplished by using a graphical method to obtain the solutions of the resonance condition. Results show that in a high (beta) plasma, wave damping causes a gap, or hole, in (mu)-space where the resonant particle scattering rate is severely depressed. It is found that only high energy ((gamma) (GREATERTHEQ) 10('5)) electrons can be trapped within a typical supernova remnant. When the notion of electromagnetic resonance is applied to particle propagation in the interplanetary ((beta)(, )<(, )1) plasma, it is found that significant modifications to the conventional scattering picture must be made. It is found that a resonance gap exists which is similar to the one in a high (beta) plasma. For electrons, this gap provides a natural explanation for scatter-free events. Theory predicts that these events should occur for kinetic energies T (LESSTHEQ) 300 keV while observations indicate that the majority have T (LESSTHEQ) 500 keV. For protons and energetic electrons, the scattering mean free path is critically dependent on the non-resonant scattering rate for particles within the gap. This fact provides a way to resolve the well known discrepancy between the theoretical and observational values for the mean free path, (lamda). Title: The propagation of energetic particles in finite temperature astrophysical plasmas Authors: Davila, Joseph Michael Bibcode: 1982pepf.book.....D Altcode: No abstract at ADS Title: The propagation of energetic particles in finite temperature astrophysical plasmas Authors: Davila, Joseph Michael Joe Bibcode: 1982PhDT........73D Altcode: No abstract at ADS Title: Effects of particle drift on the transport of cosmic rays. IV - More realistic diffusion coefficients Authors: Jokipii, J. R.; Davila, J. M. Bibcode: 1981ApJ...248.1156J Altcode: Results from numerical simulations of cosmic-ray modulations by the solar wind are presented which show that the scattering mean free path should be larger than the particle gyroradius in the average magnetic field. It is found that the difference between drift and no-drift solutions is not as great as in previous simulations, which violated the mean free path constraint stated. Profound effects are still noted for the drifts, which determine the origin of the bulk of the cosmic rays seen at any given time in the inner solar system. Accordingly, during the 1975 solar minimum, the positively charged cosmic rays seen in the inner solar system came primarily from the outer boundary near the heliospheric poles while negative particles came from the equatorial regions of the boundary. Title: A Radiation Model for the VELA Pulsar Authors: Davila, J.; Wright, C.; Benford, G. Bibcode: 1980Ap&SS..71...51D Altcode: We model the Vela emission in radio, optical and gamma wavelengths. We assume that radio emission occurs near the polar axis deep in the magnetosphere. Optical and gamma radiation arises through ordinary synchrotron mechanisms in a wide hollow cone, near the light cylinder. Fitting of observed frequencies and luminosities in the gamma and optical give reasonable plasma parameters, and indicate that field-plasma pressure balance breaks down before the light cylinder, as required by the picture. Some optical coherence is necessary if we attribute both radio and optical emission to the same species of particles, with γ∼100, but it is not required otherwise. Gamma-ray pulses arise from γ∼105 electrons. We suggest a single-pole orthogonal rotor picture which might account for the Vela pulse phases.