Dependence of the topside ion composition on the solar flux and its implication to IRI model Original Research Article

Statistical analyses of the ion density data at 1100 km altitude during the solar maximum of cycle 21 have revealed that the H+ density has negative correlation with the solar flux F10.7 while O+ has positive correlation. He+ has generally positive correlation with solar flux in the nighttime but it has negative correlation in the daytime, resulting in almost no correlation if globally averaged. The implication of these characteristics to the International Reference Ionosphere model is discussed.