Research Note

Distribution of Hα flares during solar cycle 23 ^*

Aryabhatta Research Institute of Observational Sciences, Naini Tal - 263 129, Uttaranchal, India e-mail: [bhuwan;ppant]@upso.ernet.in

Received: 10 September 2004
Accepted: 6 November 2004

Abstract

The paper presents the results of an analysis of the north-south (N-S) and east-west (E-W) distribution of Hα solar flares from 1996 to 2003. This period of investigation corresponds to the ascending phase, the maximum and part of descending phase of solar cycle 23. It has been found that the flare activity during this cycle is low compared to previous solar cycles. The pattern of N-S distribution of flare occurrence shows that after solar activity minimum in 1996 the northern hemisphere was more active in producing flares than the southern one. The dominance of northern hemisphere is shifted towards the southern hemisphere after the solar maxima in 2000 and remained there in successive years. In both hemispheres (N and S), the flares are most prolific between 11° to 20° latitudes. Although the asymmetry in the E-W distribution of flare events is low, a consistent western dominance has been found. In more intense flares (Importance ≥1) there are some longitudinal bands where flare occurrence is higher than in adjacent bands.