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  • 2010-2014  (4)
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  • 1
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    Dichotomy of Solar Coronal Jets: Standard Jets and Blowout Jets (2010)
    In:  CASI
    Details
    Publication Date: 2019-07-19
    Description: By examining many X-ray jets in Hinode/XRT coronal X-ray movies of the polar coronal holes, we found that there is a dichotomy of polar X-ray jets. About two thirds fit the standard reconnection picture for coronal jets, and about one third are another type. We present observations indicating that the non-standard jets are counterparts of erupting-loop H alpha macrospicules, jets in which the jet-base magnetic arch undergoes a miniature version of the blowout eruptions that produce major CMEs. From the coronal X-ray movies we present in detail two typical standard X-ray jets and two typical blowout X-ray jets that were also caught in He II 304 Angstrom snapshots from STEREO/EUVI. The distinguishing features of blowout X-ray jets are (1) X-ray brightening inside the base arch in addition to the outside bright point that standard jets have, (2) blowout eruption of the base arch's core field, often carrying a filament of cool (T ~10(exp 4) - 10(exp 5) K) plasma, and (3) an extra jet-spire strand rooted close to the bright point. We present cartoons showing how reconnection during blowout eruption of the base arch could produce the observed features of blowout X-ray jets. We infer that (1) the standard-jet/blowout-jet dichotomy of coronal jets results from the dichotomy of base arches that do not have and base arches that do have enough shear and twist to erupt open, and (2) there is a large class of spicules that are standard jets and a comparably large class of spicules that are blowout jets.
    Keywords: Solar Physics
    Type: M10-0868 , 4th Hinode Science Meeting; Oct 11, 2010 - Oct 15, 2010; Palermo; Italy
    Format: application/pdf
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    NASA TECHNICAL REPORTS
  • 2
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    A New Tool for Forecasting Solar Drivers of Severe Space Weather (2010)
    In:  CASI
    Details
    Publication Date: 2019-07-13
    Description: This poster describes a tool that is designed to forecast solar drivers for severe space weather. Since most severe space weather is driven by Solar flares and Coronal Mass Ejections (CMEs) - the strongest of these originate in active regions and are driven by the release of coronal free magnetic energy and There is a positive correlation between an active region's free magnetic energy and the likelihood of flare and CME production therefore we can use this positive correlation as the basis of our empirical space weather forecasting tool. The new tool takes a full disk Michelson Doppler Imager (MDI) magnetogram, identifies strong magnetic field areas, identifies these with NOAA active regions, and measures a free-magnetic-energy proxy. It uses an empirically derived forecasting function to convert the free-magnetic-energy proxy to an expected event rate. It adds up the expected event rates from all active regions on the disk to forecast the expected rate and probability of each class of events -- X-class flares, X&M class flares, CMEs, fast CMEs, and solar particle events (SPEs).
    Keywords: Solar Physics
    Type: M10-0794 , 38th Scientife Assembly of the Committee on Space Research (CSPAR); Jul 18, 2010 - Jul 25, 2010; Bremen`; Germany
    Format: application/pdf
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    NASA TECHNICAL REPORTS
  • 3
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    Onset of a Solar Filament Eruption Without a Slow-Rise Phase (2013)
    In:  CASI
    Details
    Publication Date: 2019-07-19
    Description: We observe a filament eruption of 23 Jan 2012 using Atmospheric Imaging Array (AIA) data from the Solar Dynamics Observatory (SDO) satellite. Relatively cool emissions (193 Ang. channel) show a filament with a rise-toward-eruption trajectory that is relatively smooth, without a distinct, linearly-increasing "slow rise" followed by an abrupt "fast rise," as is often seen in other events. Detailed investigations of some of those two-phase events suggested that they were triggered by magnetic flux cancellation. Here however, observations of hotter emissions (335 Ang. channel) show an adjacent eruption, invisible in 193 Ang., occurred just prior to the filament's eruption start. We surmise that the hotter eruption destabilized the 193 Ang. filament, triggering its eruption onset. In this way, the filament's smooth eruption trajectory is indicative of a non-tether-cutting eruption-onset mechanism for the filament.
    Keywords: Solar Physics
    Type: M13-2877 , 2013 American GeophySical Union (AGlD Fall Meeting; Dec 09, 2013 - Dec 13, 2013; San Francisco, CA; United States
    Format: application/pdf
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  • 4
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    A Tool for Empirical Forecasting of Major Flares, Coronal Mass Ejections, and Solar Particle Events from a Proxy of Active-Region Free Magnetic Energy (2010)
    In:  CASI
    Details
    Publication Date: 2019-07-19
    Description: This presentation describes a new forecasting tool developed for and is currently being tested by NASA s Space Radiation Analysis Group (SRAG) at JSC, which is responsible for the monitoring and forecasting of radiation exposure levels of astronauts. The new software tool is designed for the empirical forecasting of M and X-class flares, coronal mass ejections, as well as solar energetic particle events. Its algorithm is based on an empirical relationship between the various types of events rates and a proxy of the active region s free magnetic energy, determined from a data set of approx.40,000 active-region magnetograms from approx.1,300 active regions observed by SOHO/MDI that have known histories of flare, coronal mass ejection, and solar energetic particle event production. The new tool automatically extracts each strong-field magnetic areas from an MDI full-disk magnetogram, identifies each as an NOAA active region, and measures a proxy of the active region s free magnetic energy from the extracted magnetogram. For each active region, the empirical relationship is then used to convert the free magnetic energy proxy into an expected event rate. The expected event rate in turn can be readily converted into the probability that the active region will produce such an event in a given forward time window. Descriptions of the datasets, algorithm, and software in addition to sample applications and a validation test are presented. Further development and transition of the new tool in anticipation of SDO/HMI is briefly discussed.
    Keywords: Solar Physics
    Type: M10-0261 , 38th COSPAR Scientific Assembly; Jul 18, 2010 - Jul 25, 2010; Bremen, Germany; Germany
    Format: application/pdf
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