Study of major ions distribution in the outer ionosphere in the solar maximum Original Research Article

The data base created from the Bennett ion mass spectrometer measurement onboard the Intercosmos 24 satellite has been used to study altitudinal and latitudinal distributions in the altitude range of 550 to 2500 km. The behaviour of three major ions - O+, H+, and He+ during the period 1989 – 1991 (maximum of the 22nd solar cycle) in low and middle latitudes has been analysed considering seasons, local time and geomagnetic activity. Comparison of experimental profiles with the latest version of the IRI model has shown a good agreement in the case of O+ but a serious discrepancy in the case of light ions (H+ and He+) which results in an underestimate of the upper transition height by IRI.