Density structures in the martian lower thermosphere as inferred by Trace Gas Orbiter accelerometer measurements

Abstract

ESA's Trace Gas Orbiter (TGO) undertook an aerobraking campaign to lower itself into the required science orbit. We present an overview of densities derived from TGO accelerometer data during aerobraking. With the addition of density data from NASA's MAVEN/NGIMS instrument, we infer that at TGO altitudes (105 km), the atmosphere is driven by dynamics, whereas at MAVEN altitudes (>140 km), the atmosphere appears to be predominantly solar EUV-driven. We explore perturbations observed within density profiles. These are extracted and interpreted as gravity waves. Wave amplitudes are found to be around 5%. We present evidence of wave growth with altitude by comparing wave characteristics with those observed at higher altitudes. Finally, TGO density profiles are compared to profiles extracted from the Laboratoire de Météorologie Dynamique Mars Climate Database.