The Sheffield University plasmasphere ionosphere model - a review

A brief description of the Sheffield University plasmasphere ionosphere model (SUPIM) is presented. In the model, time-dependent equations of continuity, momentum, and energy balance are solved along eccentric-dipole magnetic field lines for the densities, field-aligned fluxes and temperatures of the O+, H+, He+, N-2(+), O-2(+) and NO+ ions, and the electrons. A review of some of the important results from recent studies of the model is presented. The studies show that during daytime, the equatorial plasma fountain can rise to altitudes of around 800 km at the magnetic equator and can cover magnetic latitudes of about +/-30 degrees. At regions outside the fountain, plasma flows towards the magnetic equator from both hemispheres and leads to the formation of an additional layer, the F3 layer, at latitudes close to the magnetic equator (+/-10 degrees). The peak electron density of the F3 layer can exceed that of the F2 layer for a short period of time near noon when the E x B drift is large. Associated with the enhanced electron densities of the F3 layer are reduced electron temperatures. The modelled electron temperatures and densities are in accord with observations made by the Hinotori satellite at 600 km altitude. Closer agreement in the modelled and observed values is achieved if the phase and magnitude of the meridional wind, as given by the HWM90 thermospheric wind model, are modified in accordance with the observations made by the Japanese MU radar and the AE-E satellite. There is better agreement in the modelled and observed values when the equatorial vertical E x B drift velocity model used by SUPIM has an altitude variation in accord with the observations made by the AE-E satellite and at Arecibo. (C) 1997 Elsevier Science Ltd.