On the role of F3 layers as well as solar flux in modulating the topside ionization over Indian region: An analysis

The behavior of ionization in the topside ionosphere above F region peak is quite different from the lower ionosphere owing to the diverse processes operational there. This paper presents a comprehensive study on the topside ionosphere and brings out the role of F3 layers as well as increase in solar flux in modulating the topside ionization. Data used comprises of the electron density obtained from COSMIC satellite for the period 2007 to 2012 as well as RaBIT tomograms for the period May to December 2011. This study clearly shows that the ionization in the height region of 300 km-400 km is affected by the presence of F3 layer while above 450 km ionization is not significantly altered by the formation of F3 layer during the solar minimum period. The important factor which affects topside ionization above this altitude is the solar flux. The present study has generated an empirical relationship between the topside electron density and F10.7 cm solar flux during the rising phase of solar cycle 24. This empirical relationship is compared using tomographic observations obtained from RaBIT (Radio Beacon for Ionospheric Tomography) data over Indian region.