New advances in empirical modelling of ion composition in the outer ionosphere

A new global empirical model of the relative ion composition in the outer ionosphere (altitude range of 500–2500 km) for the most important ions (O +, H +, He + and N +) has been developed. It is based on the solar minimum data from the Atmospheric Explorer satellites which have been verified over the last two decades, and on the data of the maximum of the 22nd solar cycle recorded on board the Intercosmos 24 satellite (ACTIVE mission) by a Bennett ion mass spectrometer (BIMS), the only data from a period of high solar activity in the altitude range studied. In this paper, the following is presented. (1) Validation of the ACTIVE mass spectrometer data by comparing it with newly processed results of measurements made on board the same spacecraft. (2) Linear interpolation of the logarithm of relative ion density between both solar activity extremes (to obtain model values under any level of solar activity) and comparison with OGO-6 results. (3) Comparison of the upper transition height provided by the proposed model with other transition height models.