Investigation for the cosmic ray ground level enhancements during solar cycle 23
Abstract
Major solar energetic particle (SEP) events associated with large solar flares can give rise to the cosmic ray ground level enhancements (GLEs). Up to December 2003 during solar activity cycle 23, 12 GLEs (Number from 55 to 66) have been recorded by the worldwide network of neutron monitors (NMs) in the 87 solar proton events (with peak flux exceeding 10 {(cm^2 sec ster)}-1 for more than 10 MeV solar protons ). Eeight of the 12 GLEs (67%) are originated from southern hemisphere and 10 of the 12 GLEs (83%) are originated from western hemisphere. Each GLE is corresponded by a solar coronal mass ejection (CME) which had the potential of producing disturbances to the geospace. Among the 12 relevant CMEs 8 large ones should be responsible for the 8 major geomagnetic storms (defined by disturbance storm time index ≤ -100 nT). The largest 3 geomagnetic storms (Dst≤ -300 nT) correspond to the 3 GLEs (No.59, No.65 and No.66) which have great proton flux with energy > 10 MeV. It seems to imply that the solar proton events having great proton flux are more likely to bring major geomagnetic storms. Furthermore, solar proton event with high flux is not a condition for creating GLE. Some proposal factors are discussed for GLE production.
- Publication:
-
35th COSPAR Scientific Assembly
- Pub Date:
- 2004
- Bibcode:
- 2004cosp...35.2410W