Variation of electron and ion temperatures ratio over the Indian region during the period 1995-1999 as measured by SROSS-C2 satellite

The ionospheric electron and ion temperatures data recorded by RPA payload aboard SROSS-C2 satellite during 1995-1999 have been analyzed. This paper presents the electron and ion temperature ratio over Indian region (from 5°N to 35°N latitude and from 65°E to 95°E longitude) at an average altitude of ∼500 km during 1995-1997 which include solar minimum year 1995-1996 (F10.7 less than 50), and for the period from 1998 to 1999 towards the solar maximum (F10.7 greater than 50). The ionospheric electron and ion temperatures ratio has been calculated for three different seasons: summer, winter and equinoxes. The data analysis shows that the electron and ion temperatures ratio are almost unity during night hours and greater than unity during the daytime. It was maximum at sunrise hours (from 5:00 to 7:00 LT) during all seasons, which corresponds to the sunrise overshoot. The ratio generally appears to increase with the increase of solar radio flux.