HR: 1340h
AN: SH13A-0297    [Abstracts]
TI: Variability of Size Distributions of Solar Flares
AU: * Bai, T A
EM: bai@quake.stanford.edu
AF: Stanford University, MC 4085, Stanford, CA 94305 United States
AB: In this talk, I will report an extensive study of flare size distributions for solar cycles 20--23, using Solrad and GOES data. The size distribution is variable: it varies from year to year and from cycle to cycle, and it varies with the phase of the 153-d period and with active region types. During the maximum phase of this periodicity, the size distribution is flatter. Flares from active regions producing X-class flares exhibit flat size distributions. Dependence of the size distribution on active region types is found to be the underlying cause of temporal variability of the size distribution. If complex active regions, whose flares exhibit flatter size distributions, constitute a higher percentage of the total number of active regions for a given time interval (or during the peak phase of the 153-d periodicity), the size distribution for that interval (or phase interval) becomes flatter. Ubiquity of variability of the size distribution is not compatible with an avalanche flare model.
DE: 7519 Flares
DE: 7539 Stellar astronomy
SC: SPA-Solar and Heliospheric Physics [SH]
MN: Fall Meeting 2005