RHYTHM OF SOLAR ACTIVITIES AND PREDICTION OF THE OCCURRENCE DURATIONS OF LARGE FLARES^①

Since the minimum of September in 1986, the increase in the solar activities of Cycle 22 has been kept up. The increase in the gradient of the sunspot relative number surpasses that of one of the cycle with the sun spot records. The monthly average of the sunspot relative number in December, 1988, reached to 179.4 and the smoothed average of the number in June, 1988, amounted to 118.1(1). However, the duration of large flares began from January 2, 1988, when an X1.4/3B flare erupted. Then, the eruption of large flares gradually got frequent, with the intensity being increasing. From January 1, 1988 to January 31, 1989, there erupted 44 optical flares all over Importance 2, including 3 flares of 3B, 19 X-ray flares of X and 7 proton events and all of them resulted in different geophysical effects.