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Submitted Abstracts

There are 146 abstracts


Tracking Solar Wind Input from the Sun to the Magnetosphere: 2007-2012

Author(s): M. L. Mays, O. C. St. Cyr, and H. Xie

Institution(s): NASA/GSFC and CUA

Abstract:

A statistical study of stream interaction regions and CME events during solar minimum which result in storm and substorm activity has shown that combined CME and SIR events can be more geoeffective. Events are selected based on geomagnetic activity which is characterized by indices derived from ground based magnetometers and a minimum Dst threshold of -30 nT is used. For each geoeffective event, we identified CMEs in the STEREO/SECCHI coronagraphs, and SIRs in the STEREO/SECCHI Heliospheric Imagers and associated lower coronal signatures in STEREO/EUVI and SDO/AIA. Subsequent CME and/or SIR signatures were identified in ACE, WIND, THEMIS, and other in-situ data when available. CME evolution in the lower corona and properties such as acceleration, speed and width were determined along with the in-situ plasma data for ICMEs. The propagation of these structures were tracked in the STEREO Heliospheric Imagers and subsequently in-situ. Geo-effectiveness, the strength and duration of geomagnetic activity, is compared with upstream solar wind conditions. In 2007 and 2008, SIRs produce most of the storms (~75% and ~78% respectively), however the strongest storms are produced by combined ICME and SIR interactions in 2007 and SIRs in 2008. The number of SIR driven storms drops to just below half (~46%) in 2009, and the remaining storms result from an ICME followed by an SIR (~39% and strongest storm), and ICMEs (~16%). In 2011, half of the strongest storms are driven by ICMEs, 33% are hybrid events, and SIR driven storms fell to 10%. For 2012, almost all of the strongest storms are driven by ICMEs: just over half of the storms are driven by ICMEs only, 15% are from combined events, and SIR driven are comprise a small fraction (5%).




Innovative Near Real-Time Data Dissemination Tools Developed by the Space Weather Research Center

Author(s): Marlo M. Maddox (1), Richard Mullinix (1), M. Leila Mays(1, 2), Maria Kuznetsova (1), Yihua Zheng (1), Antti Pulkkinen (1, 2), Lutz Rastaetter (1)

Institution(s): (1) NASA/GSFC, (2) CUA

Abstract:

Access to near real-time and real-time space weather data is essential to accurately specifying and forecasting the space environment. The Space Weather Research Center at NASA Goddard Space Flight Center's Space Weather Laboratory provides vital space weather forecasting services primarily to NASA robotic mission operators, as well as external space weather stakeholders including the Air Force Weather Agency. A key component in this activity is the iNtegrated Space Weather Analysis System which is a joint development project at NASA GSFC between the Space Weather Laboratory, Community Coordinated Modeling Center, Applied Engineering & Technology Directorate, and NASA HQ Office Of Chief Engineer. The iSWA system was developed to address technical challenges in acquiring and disseminating space weather environment information. A key design driver for the iSWA system was to generate and present vast amounts of space weather resources in an intuitive, user-configurable, and adaptable format - thus enabling users to respond to current and future space weather impacts as well as enabling post-impact analysis. Having access to near real-time and real-time data is essential to not only ensuring that relevant observational data is available for analysis - but also in ensuring that models can be driven with the requisite input parameters at proper and efficient temporal and spacial resolutions. The iSWA system currently manages over 300 unique near-real and real-time data feeds from various sources consisting of both observational and simulation data. A comprehensive suite of actionable space weather analysis tools and products are generated and provided utilizing a mixture of the ingested data - enabling new capabilities in quickly assessing past, present, and expected space weather effects. This paper will highlight current and future iSWA system capabilities including the utilization of data from the Solar Dynamics Observatory mission. http://iswa.gsfc.nasa.gov/




Imaging Turbulent Dynamics in Post-CME Current Sheet Structures

Author(s): David E. McKenzie

Institution(s): Montana State University

Abstract:

Turbulence in current sheets is hypothesized to produce cascades from large to small length scales, both in terms of tangled or "stochastic" magnetic fields and in the creation of "micro-current sheets". The resulting conditions are likely to have profound effects on the rate of magnetic reconnection. Whereas current sheet turbulence has historically been inferred from spectroscopic measurements of, say, nonthermal broadening, recent developments in high-resolution EUV and X-ray imaging have brought turbulence into a new light, revealing a new world of complex dynamics in the sheet-like structures connecting CMEs to post-eruption flare arcades. The image sequences demonstrate significant shears in velocity, giving the appearance of vortices and stagnations; and plasma diagnostics indicate that the plasma beta can exceed unity, suggesting that the coronal magnetic fields are significantly affected by turbulent fluid processes which produce small length scales in the current sheet. Observational characterization of the turbulent conditions will help to guide modeling efforts of post-CME current sheets, particularly in regards to cascades from CME length scales to much smaller sizes. I will present findings from an exploration of the velocity fields in the supra-arcade sheet structures, as imaged by SDO/AIA and measured with local correlation tracking.




The velocity signature of coronal jets as observed with Hinode/EIS

Author(s): K. Muglach, P.R. Young

Institution(s): NASA Goddard Space Flight Center, Artep, Inc., George Mason University

Abstract:

In this contribution we show preliminary results of a study of jets in coronal holes. We use Hinode/EIS to investigate the spectroscopic signatures of the jets and SDO/AIA and HMI to derive additional information on the plasma and magnetic field evolution. EIS was scanning a low latitude coronal hole and tracking it for about 2 days as it rotated over the solar disk. The coronal jets are best revealed through Doppler and line width maps of Fe XII 195.1 A (formed at 1.5 MK), and have sizes of 10-100 arcsec. Higher spatial and time resolution is provided by SDO: coronal and chromospheric images from AIA show the time evolution of the jet and line-of-sight magnetograms show the evolution of the magnetic footpoints of the jet. We present several examples of these extended jets and describe their properties as derived from the diagnostics we have available.




The SOLAR package on the ISS, four years of operations.

Author(s): A. Michel, N. This, C. Muller, D. Moreau, S. Klai, D. D. Van Hoof, G. Thuillier, T. Foujols, D. Bolsée, D. Gillotay, G. Scmidtke, B..Nikutowski

Institution(s): B.USOC, Space Aps, IASB-BIRA, LATMOS, Fraunjoffer Institute, PMOD

Abstract:

Since March 2008, an optical package measuring the sun spectral irradiance operates in space from the ESA COLUMBUS module of the International Space Station. Three instruments compose this package: a total solar irradiance instrument SOVIM, a UV-visible-infrared spectrometer: SOLSPEC and a far UV instrument: SOL-ACES. SOVIM stopped operations due to an electrical problem six months after launch but the two other instruments are still operating and ESA plans on supporting them until 2017. However, the life of the ISS has now been extended to 2020 and if the instruments stay in the current condition, a further extension would be possible. Due to the specificities of the ISS and mechanical limitation of the SOLAR moving platform, continuous operations is not possible and is made in intervals guaranteeing both solar visibility and minimum of contamination. This excludes arrivals of vehicles at the ISS and manoeuvres using chemical propulsion. In December 2012, NASA and the ISS partners approved a specific attitude, called the “SOLAR Attitude”, allowing the bridging of two solar viewing opportunities and thus providing quasi-continuous observations during a full solar rotation. These operations and results already reviewed by the science teams will be presented with a special emphasis on the abnormal minimum of cycle 23.




Day at Goddard

Author(s): Martha Wawro, Wendy Van Norden

Institution(s): Adnet

Abstract:

Day at Goddard is an all day event for high school students that the SDO EPO team has been running for 5 years now. During the event, students are given a tour of the integration and testing facilities, shown science on a sphere, participate in a meet and greet with scientists and engineers and participate in a hands-on lab activity. The purpose of these field trips is to increase the students’ interest in STEM subjects, expose them to STEM-related careers and increase their awareness of the research that NASA conducts.




Extracting multi-height velocity information from SDO/HMI Dopplergrams

Author(s): Nagashima, Kaori (1), Gizon, Laurent (1,2), Birch, Aaron (1), Loeptien, Bjoern (1,2), Couvidat, Sebastien (3), Fleck, Bernhard(4), Stein, Robert(5)

Institution(s): (1) Max Planck Institute for Solar System Research, (2) Institut fuer Astrophysik, Georg-August-Universitaet Goettingen, (3) Stanford University, (4) ESA ,(5) Michigan State University

Abstract:

Multi-height velocity information in the solar atmosphere is useful for many studies of the structure and dynamics of the solar atmosphere. We discuss the possibility of measuring the vertical velocity at multiple layers in the solar atmosphere using the six filtergrams of the Fe I 6173A absorption line obtained by SDO/HMI. In the standard HMI pipeline processing, these filtergrams are combined to estimate a single Doppler velocity. Here we construct three Dopplergrams by computing pair-wise differences between intensities in the blue and red wings of the line. We use realistic numerical simulations of convection to evaluate the range of heights that contribute to each of our multi-height velocity estimates. The cross-spectra of the Dopplergrams contain interesting information about vertical wave propagation in the solar atmosphere.




SDO AIA Observations of Large-Scale Coronal Disturbances in the Form of Propagating Fronts

Author(s): Nitta, Nariaki V. (1), Schrijver, Carolus J. (1), Title, Alan M. (1), Liu, Wei (1) (2)

Institution(s): (1) Lockheed Martin Advanced Technology Center (2) Stanford University

Abstract:

One of the most spectacular phenomena detected by SOHO EIT was the large-scale propagating fronts associated with solar eruptions. Initially these 'EIT' waves were thought to be coronal counterparts of chromospheric Moreton waves. However, different spatial and kinematic properties of the fronts seen in H-alpha and EUV images, and far more frequent occurrences of the latter have led to various interpretations that are still actively debated by a number of researchers. A major factor for the lack of closure was the various limitation in EIT data, including the cadence that was typically every 12 minutes. Now we have significantly improved data from SDO AIA, which have revealed some very interesting phenomena associated with EIT waves. However, the studies so far conducted using AIA data have primarily dealt with single or a small number of events, where selection bias and particular observational conditions may prevent us from discovering the general and true nature of EIT waves. Although automated detection of EIT waves was promised for AIA images some time ago, it is still not actually implemented in the data pipeline. Therefore we have manually found nearly 200 examples of large-scale propagating fronts, going through movies of difference images from the AIA 193 A channel up to January 2013. We present our study of the kinematic properties of the fronts in a subset of about 150 well-observed events in relation with other phenomena that can accompany EIT waves. Our emphasis is on the relation of the fronts with the associated coronal eruptions often but not always taking the form of full-blown CMEs, utilizing STEREO data for a subset of more than 80 events that have occurred near the limb as viewed from one of the STEREO spacecraft. In these events, the availability of data from the STEREO inner coronagraph (COR1) as well as from the EUVI allows us to trace eruptions off the solar disk during the times of our propagating fronts. The representative relations between the fronts and CMEs will be discussed in terms of the evolution of EIT waves observed in different channels of AIA, which provide information of the thermal properties of the fronts. Our study will further clarify the variety of solar eruptions and their associated manifestations in the corona.




Stray Light Correction for HMI Data

Author(s): A.A. Norton, T. Duvall, J. Schou, M. Cheung

Institution(s): Stanford University

Abstract:

Our goal is to find a deconvolution routine that can remove scattered light in sunspot umbrae without introducing extraneous power in high spatial frequencies in helioseismology analysis of the same data. Using ground-based calibration data, a third-order polynomial fit was obtained for the instrumental modulation transfer function (MTF). Images of the solar limb and the limb and disk of Venus during its transit were used to model stray light. An Airy function and a Lorentzian are used in combination to model the instrumental point spread function (PSF) for HMI which is made to be positive definite everywhere and zero above the ideal optical Nyquist frequency. Deconvolution was carried out using a Lucy-Richardson algorithm on a graphics processing unit. The deconvolved image is then compared to the original to determine the extent of introduced Gibb's phenomenon (ringing) and how the power changes as a function of spatial frequency.




New frontiers in wave studies and coronal seismology

Author(s): Leon Ofman

Institution(s): CUA/NASA GSFC

Abstract:

The launch of the SDO and the unprecedented high resolution, high cadence observations with AIA provide new details on wave activity in the solar corona. These observations, supplemented by spectroscopic data from Hinode/EIS, theory, and numerical modeling open new frontiers in wave studies and in coronal seismology - the use of waves for the determination of the physical parameters (such as the magnetic field and density) in the corona. The idealized theoretical wave studies were recently expanded by sophisticated there-dimensional MHD models that include additional phenomena, such as more realistic coronal loop magnetic and density structure, broad band waves, and quasi-periodic flows, enabling further expansion of coronal seismology as a tool for coronal plasma diagnostics. I will review the recent progress in observational and theoretical studied of waves and the development of coronal seismology.





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Last Updated on Tuesday, 29 March 2011 09:36