Some Results of Electron Content Measurements at Delhi From Faraday Fading of S‐66 Transmissions

Abstract

This paper contams the results of analysis of the total electron content (Is) measurements made from the recordings of Faraday rotation at Delhi of the 20‐ and 40‐Mc/s transmissions of the satellite Explorer 22 (S‐<16) for the period October 1964 through June 1965, the period of low solar activity. The results show that the diurnal maximum is reached around 1300‐1400 1ST, while at night the electron content falls to low values, decreasing slowly with time until 0600 when it starts to increase. The variations in Isclosely follow the f0F2, variations. The ratio I, smax/Isminincreases from 7 for OctoberDecember 1964 through 10 for January‐March 1965 to about 25 for April‐June 1965. It is interesting to note that electron content values are more or less independent of solar activity until the 10‐cm solar flux exceeds about 80 units. Above 80 units, there is a positive correlation. The study of dependence ofIson magnetic activity shows that there is posiiive correlation during daytime, while nighttime values do not show any dependence on magnetic activity. In addition, the electron content seems to have a correlation with solar zenith angle. General features of the thickness parameter T and the ratio of total to subpeak electron contemIs//b are also given. The variations ofT are correlated with both solar flux anJ hm‐F~ variations. Preliminary examination of occurrence of scintillations is also given.