Periodic behavior of solar electron flares during descending phase of cycle 23

Abstract

We report for the first time the short and intermediate-term periodicities in solar electron flares in two different energy bands during the recent solar minimum of cycle 23 using 5.7- year data (1 June 2003 to 31 December 2008) from the Geostationary Operational Environmental Satellites (GOES). The wavelet power spectrum analysis shows a number of quasi-periodic oscillations in both data sets. In the high frequency range, prominent periods of 10- 16 days, 22-35 days including 27-day oscillation are detected. Other quasi-periods such as 40-60 days, 100-110 days, 120-130 days, 140-160 days, 180-190 days, around 250 days, ∼ 400 days and ∼1.3 years are found in different phases of descending epoch of cycle 23. Possible explanations of the observed periodicities are given in terms of solar rmode oscillations.