Some observations on the sporadic E-region at Calcutta

Simultaneous observations of the radio waves reflected from the E-layer and the F layer have been made at Calcutta covering a series of frequencies. The apparent reflection coefficient of the E(s) layer and its dependence on frequency have been studied for various occasions. The temporal development of the E(s) and F echoes and their independences are investigated. Attempts have also been made to estimate the time variation of the peak of ionization during the growth and decay phases of the E(s) layer. A somewhat larger wind gradient and also apecies having a lower limit of α of about 10-8cm3sec-1 are necessary to explain the time variations of the estimated ionization values