NORTH AND SOUTH MAJOR FLARE PERIODICITIES DURING SOLAR-CYCLE-20

The periodicities of monthly values of major flare numbers and compreh ensive major flare Index (CFI) have been studied for the 20(th) solar cycle. It has been proved that the periodicity 152 days exists also in the southern (S) solar hemisphere. This periodicity has been previous ly defined in the earlier cycles to be a northern (N) periodicity, but It has migrated to the southern hemisphere (S) during the cycles 19, 20, 21. For the whole solar disk data, it has been found that the peri odicity at 78.43(d) is much remarkable than its first harmonic at 156. 863. We have also detected very strong periodicity at 548.96(d) in N-h emisphere while a strong one has been found near 100(d) in both solar hemispheres. The detected periodicities at 80-(+)2(d) and 101-(+)1(d) seems to have a global origin. The 87.1(d) periodicity is present and it is suggested that it is related to 88(d) periodicity attributed to the tidal influence of the planet Mercury on sunspots. Both hemisphere s present their periodicities independently.