SOME RESULTS OF NIGHTTIME SCINTILLATIONS AT LOW-LATITUDE

Ionospheric scintillation observations of VHF radio signals from FLEET SAT satellite (73-degrees-E longitude) at Bhopal from January 1990 to December 1990 have been used to study the characteristic variations of scintillation activity. It is found that scintillation occurrence is essentially a night-time phenomenon and day-time scintillations are ve ry rare. Annual average nocturnal variation of percentage occurrence o f scintillations shows maximum at around 2100-2200 hours LT. Seasonall y, scintillations are most prominent during equinoxes and least during summer. Geomagnetic disturbances tend to decrease the occurrence of s cintillations in the pre-midnight period.