Daytime amplitude scintillations at a low latitude station, Calcutta

Abstract

The paper deals with ionospheric scintillations of the 136 MHz signal from the geostationary satellite ETS-II observed during daytime at Calcutta (23°N; 88.5°E; 32°N dip) which is situated well outside the equatorial electrojet region. Observations over a solar cycle (1977-1986) show that daytime scintillation occurrence with sunspot number. Simultaneous record of Faraday polarization angle of the satellite signal shows that all the cases of daytime scintillations occur when there are definite signatures of travelling ionospheric disturbances (TIDs) which are manifestations of atmospheric gravity waves. However, the reverse is not true. There are days when the Faraday rotation record exhibited periodic structures but no scintillation in amplitude was observed.