AN EVALUATION OF THE TURBOPAUSE ALTITUDE USING n (He) OBSERVED AT PERIGEES OF AE-D SATELLITE
用AED卫星近地点上观测的n(He)估算湍流层顶高度

In this paper, variations of AE-D's perigee altitudes, the corresponding atmospheric expansion and the density distributions are analyzed. At same heights but on different latitude areas, the density of the lower thermosphere is more intense at low latitude than that at high latitude. So does the satellite drag. Therefore, the perigee is lower at low latitude and it is lower by day than at night. Besides, the data of n(He) observed at perigees are used to roughly estimate the altitudes of the turbopause Z t and their variations according the two distinct vertical distributions of atmospheric composition in low and upper atmospheres: the homogeneous mixing and the diffusive separation. The results show that Z t is almost not related to latitude at high latitude areas, while its response to the magnetic storm is very clear. On the other hand, at low latitude areas Z t increases as the latitude decreases, and the value of Z t is larger by day than at night.