A morphological study of VHF scintillations at Agra

Abstract

A morphological study of scintillations in the VHF signals at 244.16 MHz from satellite, FLEETSAT, has been made at Agra (geogr. Lat., 27.2°N; geogr. Long., 78°E) and reported in this paper. It is shown that the scintillations occurred at Agra mostly during nighttime, predominantly in pre-midnight hours, with peak-to-peak amplitude variation of less than 15 dB. The occurrence is highly increased during equinoxes and considerably reduced during summer. The activity is found to vary substantially during magnetically disturbed periods in the post- and pre-midnight hours of winter and summer. The daytime scintillations are slow and weak and occur rarely. The scintillation index for nighttime scintillation fluctuates between 20 and 45% from pre- to post-midnight hours in winter and equinoxes and falls smoothly below 10% in summer. Most of the present results are found to be similar to those at Varanasi (another station outside the anomaly zone), but differ markedly with those at other stations near and inside the zone.