Improving the 75 to 300 km ion composition model of the IRI

Abstract Mainly based upon a detailed analysis of many mass spectrometer rocket measurements in the 100 to 200 km height range a new ion composition model for the 75 to 300 km altitude range has been developed in terms of relative ion concentrations. Above 200 km the decrease of molecular and increase of atomic ions could be specified by using additional data from other techniques. Below 100 km clustered ions are considered as one additional species. The new model may be usable as a substitute of the corresponding block in the present IRI.