Estimation of the plasmasphere electron density and O+/H+ transition height from Irkutsk incoherent scatter data and GPS total electron content

Observations obtained using the Irkutsk Incoherent Scatter Radar (ISR) and GPS Total Electron Content (TEC) were used for estimation of the O+/H+ transition level and electron density distribution in the upper topside ionosphere and in the plasmasphere. We use a modified Chapman function where O+/H+ transition level is one of parameters to develop a model. On the base of this model we consider some examples of O+/H+ transition height dynamics and estimate the uncertainty of the method. We show that the transition height dynamics is very sensitive to parameters of neutral wind and it has specific variation on Irkutsk ISR site. The plasmasphere can contribute more than 50% to GPS TEC, and the input from plasmasphere can produce significant influence on GPS TEC variations.