A comparison of the lower transition height obtained with a theoretical model and with IRI

Abstract

The ionospheric low transition height obtained from a theoretical model is compared to the IRI model using the standard ion composition option and the Danilov and Yaichinikov model option, and to Oliver's model. It is found that 1) the three models agree rather well by day except in summer for low solar activity, while large differences exist by night; 2) the day-night difference of the transition height by the IRI standard option is much smaller in summer and in winter, but is larger in equinox seasons in low solar activity, while the Danilov and Yaichnikov model always yields a rather small difference; 3) increasing solar activity leads to higher theoretical levels particularly by night, while IRI shows an opposite trend. 4) due to transport by wind the simulation gives a transition height depending on local time, while both IRI options take the solar zenith angle for variable. As for the ion composition above 150 km, the distributions of the relative percentage of O + as well as NO + at noon in summer and winter under low solar activity predicted by the theoretical model are approximately consistent with those of the Danilov and Yaichnikov model.