Statistical analysis of the X-ray flares (M ≥ 1) during the maximum period of solar cycle 22

¹ CCAST (World Laboratory), P.O. Box 8730, Beijing, 100080, China
² Yunnan Observatory, Kunming, China
³ Observatoire de Paris, Section de Meudon, URA 2080, 92195 Meudon Principal Cedex, France
⁴ University of Oslo, Blindern, P.O. Box 1029, Norway

Send offprint request to: B. Schmieder

Received: 19 March 1997
Accepted: 11 February 1998

Abstract

The data of the X-ray flare events of class during the interval of 1987 to 1992 corresponding to the maximum period of the 22nd solar cycle have been investigated to study the North-South (N-S) and West-East (W-E) asymmetries. During that period it has been shown the existence of a real N-S asymmetry. That confirms recent studies done by using other indicators, such as sunspot areas (Oliver & Ballester 1994). The E-W asymmetry during that period is not significant but a non uniform flare distribution in longitude has been evidenced. That result is also in good agreement with the work made by Joshi (1995) using Hα flares for the same time period. We have shown that the behaviour of the reverse tendency of Solar Cycle 21 to exhibit a predominance of the southern hemisphere in the N-S asymmetry compared to the previous Solar Cycles (19 and 20) is maintained for Solar Cycle 22. A long period cycle of the N-S asymmetry could be suspected.