NORTH-SOUTH ASYMMETRY IN THE SOLAR-FLARE INDEX

This paper reports the results of a study of the N-S asymmetry in the flare index using the results of Knoska (1985) combined with our resul ts for the solar cycles 17 to the current cycle 22. By comparing the t ime-variation of the asymmetry curve with the solar activity variation of the 11-year cycle, we have found that the flare index asymmetry cu rve is not in phase with the solar cycle and that the asymmetry peaks during solar minimum. A periodic behaviour in the N-S asymmetry appear s: the activity in one hemisphere is more important during the ascendi ng part of the cycle whereas during the descending part the activity b ecomes more important in the other hemisphere. The dominance of flare activity in the southern hemisphere continues during cycle 22 and, acc ording to our findings, this dominance will increase gradually during the following cycle 23.