Total Electron Content Observations at Calcutta with Geostationary Satellite INTELSAT 2F2

Abstract

Observations on a geostationary satellite over the Indian subcontinent have been carried out at Haringhata Field Station of the University of Calcutta (geogr. lat., 22° 58'N, long., 88° 30'E; magnetic dip, 32°N) with the help of INTELSAT 2F2 transmitting at 136'44 MHz The Faraday fading data obtained during winter 1972-73 have been analyzed to determine electron content, slab thickness 2nd effect of magnetic activity on nighttime content at a location with sub-ionospheric latitude of 20^oN and longitude 90^oE. The diurnal curves of electron content during the winter months indicate a range of about 1: 12. A considerable day-to-day variability in the midday values as well as variability in the time of onset for the afternoon decay is observed. The rate of increase in electron content after sunrise is substantially constant at 10¹⁵ el. M^-2 min^-1 upto about 0930 hrs IST and shows an abrupt increase thereafter by nearly a factor of 3 when ionization from the equatorial region diffuses into the local ionosphere. The period under study was marked by several weak-to moderate magnetic storms, which induced high values of midnight content as large as 100% above the mean value.