Semi-empirical models of the neutral atmosphere based on turbopause height and exospheric temperature variations

Abstract

Based on mass spectrometer observations of the satellites Ogo 6 and Esro 4 the long periodic density variations of He, O, N 2 and Ar are interpreted to be a result of combined variations of the exospheric temperature and the turbopause height. Only these two parameters are used in the models. Thus in comparison with previous models the number of parameters needed is significantly reduced. This simplification does not diminish the accuracy of the analytic representation of the observations and provides new physical insight into the processes which govern the dynamic behaviour of the neutral thermosphere. The annual variation of the turbopause height is found to cover the height range between 90 and 115 km and is approximately equal for both the Ogo 6 and the Esro 4 data.