COSMIC TEC tomographic vertical density reconstructions of the topside ionosphere and plasmasphere: Differences between the American and African sectors

Global Positioning System (GPS) navigation measurements have become useful in observing the ionospheric spatial electron density distribution TEC from ground-based receivers are biased by the high density around the F2 peak and therefore it is difficult to extract information about the topside ionosphere and plasmasphere. GPS measurements onboard Low Earth Orbiting (LEO) satellites provide more detailed observations of the ionospheric electron density distribution from the orbit height of the LEO satellite to GPS orbit heights. We use GPS TEC measurements onboard COSMIC satellites to reconstruct the topside ionosphere and plasmasphere electron density distribution for both geomagnetically quiet and disturbed conditions during over-flights of the American and African mid-latitude regions by the COSMIC spacecraft using algebraic tomographic reconstruction technique (ART). The reconstructions provide more detailed information of the longitudinal and vertical spatial structure of topside ionosphere and plasmasphere during both geomagnetically quiet and disturbed conditions, and indicate the great potential of evaluating ionospheric models in the topside ionosphere/plasmasphere altitude range.