Low latitude, topside ionosphere composition and its variation with changeable solar activity

Abstract

The ions composition and their densities have been studied for different solar activity periods - along with their diurnal, seasonal and annual variations - for half of the 23rd solar cycle, covering solar minima (1995) to solar maxima (2000) over Indian sector (65–95ᵒE and 5–35ᵒN) at an average altitude of ~500 km. The study has been done by processing the data obtained from in situ measurement made by separate Retarding Potential Analyser (RPA) for electrons and ions, aboard Indian satellite SROSS C2. The plasma density has been found to be rich in O+ ion for all instances of time and showed a direct increase with solar activity. H+ has been observed to be in plenty during night time, especially from moderate to high solar activity period. The difference between H+ and O+ densities widens with increasing value of F10.7. He+ always constitutes a small part of plasma but its density exceeds H+ - during moderate to high solar activity period. O2+ has beenfound to be a minor constituent, even 3-4 folds lesser than He+ density. A positive correlation with solar activity has been found for O2+.