Magnetic storm characteristics of the thermosphere


  • H. G. Mayr,

  • H. Volland


Energy and diffusive mass transport associated with the thermospheric circulation are considered in a self-consistent, though mathematically relatively simple, form to describe in a three-dimensional two-constitutent model magnetic storm characteristics in composition (N2, O, and He), temperature, and mass-density. It is shown that during disturbed conditions the latitudinal variations of composition and gas temperature Tg reflect the local nature of the magnetic storm heat input assumed to be primarily confined to the auroral zones. Thereby Tg and N2 increase, He decreases, and O remains constant through the auroral zones at exospheric heights (due to the superposition of temperature and diffusion effects) in agreement with Ogo 6 mass spectrometer measurements. In contrast, the magnetic storm response in the total mass density is characterized by a strong worldwide component and a relatively insignificant increase toward the poles, with the density peak occurring between 2 (poles) and 8 (equator) hours after the maximum energy input, in substantial agreement with satellite drag data. While in situ composition and satellite drag mass-density measurements can thus be reconciled, it must, however, be emphasized that the temperature derivation from the satellite drag data cannot be justified during disturbed conditions.