“…This is popularly known as the "Fountain Effect." The various aspects of equatorial anomaly have been studied quite extensively both experimentally and theoretically (RASTOGI, 1959(RASTOGI, , 1966RASTOGI and RAJARAM, 1971;DUNCAN, 1960;LYON, 1963;MOFFETT and HANSON, 1965;BRAMLEY and PEART, 1965;HANSON and MOFFETT, 1966;ANDERSON, 1971;RAJARAM and RASTOGI, 1974; Rotation measurements, which give ionospheric Total Electron Content (TEC), are being widely used for ionospheric studies. Latitudinal variation of TEC has been studied by various workers (BASU and DAS GUPTA, 1968;TITHERIDGE and SMITH, 1969;MENDONCA et al, 1969;GOLTON and WALKER, 1971;RASTOGI et al, 1973RASTOGI et al, , 1975IYER et al, 1976).…”