Ways to improve the current IRI ion composition model with regard to low solar activity and its extension to the plasmasphere

Knowledge of the ion composition in the outer ionosphere and plasmasphere is critically important for fully understanding the propagation of radio waves in this region and for the many applications that use ray-tracing through this region. The TTS-03 model currently used in the International Reference Ionosphere (IRI) it is restricted to altitudes below 2000km and is based on data from the solar activity interval F10.7_daily= 85 to 200. Thus it does not represent well the peculiarities of the ionosphere during the very low solar activity years 2009 and 2010. By using newly available data from the satellite C/NOFS and recently restored data from the OGO-5 satellite we are working towards overcoming these shortcomings of the current IRI ion compistion model. In this talk we will firstly report about our comparisons of the TTS-03 model with measurements during the very low solar activity years 2009-2010 and wewill suggest possible improvements of the TTS-03 model. We will secondly propose an extension of the TTS-03 model to the plasmasphere with the help of the OGO-5 data. We also present a check of the consistency of the OGO-5 ion composition data, specifically, we will focus on the H+/He+ ratio. In both cases we discuss the results with assistance of the simulations with the FLIP model.