COSMIC-RAY MODULATION NEAR THE ONSET AND MAXIMUM PHASES OF SOLAR-ACTIVITY CYCLE-22

Solar activity cycle (SAC) 22 has been full of surprises. Using data obtained with the neutron monitors located at Huancayo and Deep River, we have studied the cosmic ray modulation of the five-year developmental phase of SAC 22. The main characteristics of the observed modulation are compared with those of cycle 19. The similarities and differences between the two cycles are noted. The data indicate that the amplitude of the observed modulation is larger at higher and lower primary rigidities than that for cycle 19, which still remains the most active cycle. The lowest ever monthly-mean counting rates were obtained in June 1991. Even so, based upon our prior experience, we expect the recovery of the cosmic ray intensity in SAC 22 to follow the pattern observed for cycles 20 and 18, rather than that for cycle 19.