SOLAR-ACTIVITY DEPENDENCE OF INTERPLANETARY DISTURBANCES

Interplanetary scintillation measurements obtained inside 200 R. using the Ooty Radio Telescope during August 1986 - April 1991 have been an alysed to study the interplanetary disturbances (or events) and their occurrence rates st various phases of the solar cycle. The disturbance s are identified by the increase in the level of scintillation compare d with the expected value. In total, 735 events have been identified. The results show a rate of 0.49 events per day near solar maximum and a low rate of 0.16 events per day during minimum of activity. The resu lts are compared with coronal mass ejection (CME) rates and transients rates obtained from the Doppler scintillation measurements.