HAO Colloquium - Gunther March, TU Delft

Thermosphere density and wind from satellite acceleration observations

The CHAMP, GRACE, GOCE and Swarm satellites have been very productive missions to improve the understanding of atmospheric dynamics and coupling processes in the thermosphere-ionosphere region. Accelerometers and GPS-receivers on board of these satellites provided, and are providing, high-resolution thermosphere products. However, scale differences of such satellite data with respect to empirical models have so far been largely neglected or removed using ad hoc scale factors. The source of these differences arises from errors in the satellite geometry, aerodynamics and gas-surface interactions (GSI) modelling. Previously used simplified models could not provide high-fidelity information about satellite outer surfaces and energy exchanges between atmospheric particles and satellites.

Within the presented research, we aim to reduce these uncertainties by using an enhanced geometry and aerodynamic modelling with a better characterization of gas-surface interactions. The satellite accelerations have been reprocessed using newly estimated GSI parameters leading to high-fidelity density and wind estimates. Long periods and attitude manoeuvres have been investigated in order to provide an overview of GSI modelling influence and the associated thermospheric products sensitivity. The improved densities and winds are presented and compared with empirical atmospheric models. The presented improved products are expected to be useful to the thermosphere-ionosphere science community to further increase the understanding of atmospheric dynamics as well as the effects of space weather and space climate on satellite orbits.

Date and time: 
Wednesday, June 12, 2019 - 2:00pm to 3:00pm