Revisiting the SHH and SEP Link
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==Introduction== | ==Introduction== | ||
| - | Two previous Nuggets have debated the possibility of a link between solar energetic particle (SEP) events and "soft-hard-harder" (SHH) spectral behavior in solar flares. In [http://sprg.ssl.berkeley.edu/~tohban/nuggets/?page=article&article_id=46 "Soft-Hard-Harder"], Sam Krucker and Hugh Hudson discussed five RHESSI flares that confirmed this relation, but Gerry Share and Allan Tylka later questioned the link when considering five more RHESSI and Yohkoh events in [http://sprg.ssl.berkeley.edu/~tohban/wiki/index.php/SEPs_Link_not_Confirmed "SEPs Link not Confirmed"]. | + | Two previous Nuggets have debated the possibility of a link between solar energetic particle (SEP) events and "soft-hard-harder" (SHH) spectral behavior in solar flares. In [http://sprg.ssl.berkeley.edu/~tohban/nuggets/?page=article&article_id=46 "Soft-Hard-Harder"], Sam Krucker and Hugh Hudson discussed five ''RHESSI'' flares that confirmed this relation, but Gerry Share and Allan Tylka later questioned the link when considering five more ''RHESSI'' and ''Yohkoh'' events in [http://sprg.ssl.berkeley.edu/~tohban/wiki/index.php/SEPs_Link_not_Confirmed "SEPs Link not Confirmed"]. |
| - | This correlation was originally studied by [http://adsabs.harvard.edu/abs/1995ApJ...453..973K Alan Kiplinger], using 10 years of data from the Hard X-ray Burst Spectrometer aboard the ''Solar Maximum Mission''. Kiplinger found that 96% of SEP-producing flares were predicted by SHH behavior, suggesting that the two processes are somehow linked. This strong statistical correlation alone is | + | This correlation was originally studied by [http://adsabs.harvard.edu/abs/1995ApJ...453..973K Alan Kiplinger], using 10 years of data from the Hard X-ray Burst Spectrometer aboard the ''Solar Maximum Mission''. Kiplinger found that 96% of SEP-producing flares were predicted by non-thermal, hard X-ray (HXR) SHH behavior, suggesting that the two processes are somehow linked. This strong statistical correlation alone is interesting for space-weather prediction applications, but confirming or discrediting the link is also important for motivating further investigation into the actual dynamics that could relate the two phenomena. |
| - | Here we present the results of [http://www.iop.org/EJ/abstract/0004-637X/707/2/1588/ our recent study] on the subject. Our findings appear to ratify the correlation between SHH and SEP occurrence, in agreement with Kiplinger. | + | Here we present the results of [http://www.iop.org/EJ/abstract/0004-637X/707/2/1588/ our recent study] on the subject. Our findings appear to ratify the statistical correlation between SHH and SEP occurrence, in agreement with Kiplinger's work. |
| - | == | + | ==Online Catalog of Events== |
| - | + | For this study, we initially gathered ''RHESSI'' observations of all 661 X- and M-class flares from 2002 February 12 through the end of Solar Cycle 23 . Flares were also limited to solar locations between West 30<math>^\mathrm{o}</math> and West 90<math>^\mathrm{o}</math>, as these western longitudes are more likely to connect SEPs to Earth by interplanetary magnetic field lines. After eliminating flares without sufficient observational coverage by ''RHESSI'' and those without non-thermal HXR emission above background levels, we were left with 84 flares that were further analyzed for SHH behavior. SEP events were determined by particle flux observations at Earth. The data we used included ''GOES'' proton flux measurements and both proton and electron data from the 3DP instrument aboard ''WIND''. | |
| - | == | + | A full catalog of all our flares, along with SEP event data and SHH analysis is [http://sprg.ssl.berkeley.edu/~jgrayson/ available online]. The online catalog also serves as a quick general reference of all ''RHESSI'' observations of major flares, complete with spectrograms and accompanying ''GOES'' soft X-ray lightcurves. |
| + | |||
| + | ==Spectral and Energetic Particle Analysis == | ||
==Conclusion== | ==Conclusion== | ||
Revision as of 03:03, 18 January 2010
Contents |
Introduction
Two previous Nuggets have debated the possibility of a link between solar energetic particle (SEP) events and "soft-hard-harder" (SHH) spectral behavior in solar flares. In "Soft-Hard-Harder", Sam Krucker and Hugh Hudson discussed five RHESSI flares that confirmed this relation, but Gerry Share and Allan Tylka later questioned the link when considering five more RHESSI and Yohkoh events in "SEPs Link not Confirmed".
This correlation was originally studied by Alan Kiplinger, using 10 years of data from the Hard X-ray Burst Spectrometer aboard the Solar Maximum Mission. Kiplinger found that 96% of SEP-producing flares were predicted by non-thermal, hard X-ray (HXR) SHH behavior, suggesting that the two processes are somehow linked. This strong statistical correlation alone is interesting for space-weather prediction applications, but confirming or discrediting the link is also important for motivating further investigation into the actual dynamics that could relate the two phenomena.
Here we present the results of our recent study on the subject. Our findings appear to ratify the statistical correlation between SHH and SEP occurrence, in agreement with Kiplinger's work.
Online Catalog of Events
For this study, we initially gathered RHESSI observations of all 661 X- and M-class flares from 2002 February 12 through the end of Solar Cycle 23 . Flares were also limited to solar locations between West 30o and West 90o, as these western longitudes are more likely to connect SEPs to Earth by interplanetary magnetic field lines. After eliminating flares without sufficient observational coverage by RHESSI and those without non-thermal HXR emission above background levels, we were left with 84 flares that were further analyzed for SHH behavior. SEP events were determined by particle flux observations at Earth. The data we used included GOES proton flux measurements and both proton and electron data from the 3DP instrument aboard WIND.
A full catalog of all our flares, along with SEP event data and SHH analysis is available online. The online catalog also serves as a quick general reference of all RHESSI observations of major flares, complete with spectrograms and accompanying GOES soft X-ray lightcurves.
