Parameterisation of the local and non-local processes in the thermospheric energy budget based on DE-2 satellite data

Abstract

Though the mechanism redistributing the energy and momentum between the neutral and ionised species of the upper atmosphere i.e. thermosphere and ionosphere system (TIS) over low and equatorial latitudes are understood reasonably well, only few individual processes could be modeled so far. As a result, the most widely used thermospheric model (MSIS) is found to fall short of the true prediction of low latitude thermospheric temperatures and its variabilities. Large scale local processes like equatorial ionisation anomaly (EIA) and equatorial temperature and wind anomaly (ETWA) do affect the thermal structure of this region significantly. Apart from that, the effect of the processes which are essentially non-local in origin like the one that could be represented by the variabilities in earth's ring currents, also contribute to the thermal structure and its variabilities. The present paper deals with parameterisation of these local and non-local processes and suggests ways of incorporating the same in the existing MSIS model. It has been demonstrated that the whole exercise leads to a significant improvement in the MSIS which is now able to make very good predictions, with regard to the variabilities and in terms of absolute magnitudes on more than 50-60% of the events studied. The present results take us closer towards a realistic model for low/equatorial latitudes.