The investigators improve specification of the topside electron density and ion composition, using the International Reference Ionosphere (IRI) model. Investigating the global and temporal variations of previously determined topside model parameters, they establish a functional description of these variations in terms of universal time, local time, season, solar cycle, magnetic activity and geographic and geomagnetic coordinates. Using incoherent scatter data, they investigate the profile shape near the F peak, an activity necessary in merging the new topside model with F peak models applied in IRI. In addition, they study global and temporal variation patterns of characteristic topside ion composition parameters; like the upper transition height, where ion gas consists to equal parts of light ions and atomic oxygen ions, and the ratio of ionized helium to ionized hydrogen. The ultimate goal of these systematic evaluations is to establish parameters that are most influential in different altitude regimes and the underlying physics.
