An Assimilative Version of TIE-GCM using PDAF

The TIE-GCM (Thermosphere Ionosphere Electrodynamics General Circulation Model) is a numerical model of the upper atmosphere, providing extensive information about the neutral and charged particles therein. It enables simulations of the neutral density that is required to compute the drag acceleration acting on satellites. We have developed an assimilative version of the TIE-GCM using PDAF (Parallel Data Assimilation Framework), to improve the neutral density modeling and the derived drag acceleration. Here, we present an experiment in which we assimilate neutral densities from a calibrated empirical model into the TIE-GCM: In a first step, we have scaled the NRLMSIS2.0 with densities derived from the CHAMP accelerometer, then evaluated it on a regular grid and finally assimilated the neutral densities into the TIE-GCM. We assess the performance of the assimilation framework using densities derived from the CHAMP and GRACE acceleromerters. The investigated time period includes quiet and stormy conditions.