Nighttime radio wave scintillation at equatorial stations in Indian and American zones

Results are presented on VHF radio wave scintillation at 244 MHz recorded during nighttime at the Trivandrum station (India) since July 1985. These are compared with the data on scintillations at 137 MHz observed at another equatorial station, Huancayo in the American sector, for the period June 1969-May 1970. It was found that whereas in the Indian sector the seasonal variation of scintillatons exhibit maxima during the two equinoxes, the scintillations observed in the American sector exhibit only single maxima, which were observed during the December solstices. Moreover, with a decrease of solar activity, the scintillation activity decreases in the Indian sector much faster than in the American sector.