Response of the topside and bottomside ionosphere at low and middle latitudes to the October 2003 superstorms

The topside TECs above hmF₂ at low and middle latitudes showed significant increases during storm time; however, the bottomside TEC below hmF₂ did not show so obvious changes. Consequently, the bottomside ionosphere made only a minor contribution to the ionospheric positive phase seen in the total TEC at low and middle latitudes. Moreover, at middle latitudes F₂ peak electron densities during storm time did not have the obvious enhancements that were seen in both the ground-based and topside TECs, although they were accompanied by increases of hmF₂.

Therefore, storm time TEC changes are not necessarily related to changes in ionospheric peak densities. Our results suggest that TEC increases at low and middle latitudes are also associated with effective plasma scale height variations during storms.