Density Fluctuations in the Lower Thermosphere of Mars Retrieved From the ExoMars Trace Gas Orbiter (TGO) Aerobraking

• Published in: Atmosphere Vol. 10; no. 10; p. 620
• Main Authors: Jesch, David, Medvedev, Alexander S., Castellini, Francesco, Yiğit, Erdal, Hartogh, Paul
• Format: Journal Article
• Language: English
• Published: Basel MDPI AG 01.10.2019
• Subjects: Accelerometers; Aerobraking; Altitude; Atmosphere; atmospheric dynamics; atmospheric science; Cooling; Density; Density profiles; Dependence; Distribution; Diurnal variations; Earth; Exponential functions; General circulation models; Gravitational waves; Gravity; Height; HyperText Markup Language; Lower thermosphere; Manganese; Mars; mars atmosphere; Mars thermosphere; Mean temperatures; Middle atmosphere; Predictions; Propagation; Scale height; Semantics; Solar tides; Thermosphere; Trace gases; upper atmosphere; Vertical distribution; Winter; Zonal winds; United States > US; Germany
• ISSN: 2073-4433; 2073-4433
• DOI: 10.3390/atmos10100620

The upper atmosphere of Mars is constantly perturbed by small-scale gravity waves propagating from below. As gravity waves strongly affect the large-scale dynamics and thermal state, constraining their statistical characteristics is of great importance for modeling the atmospheric circulation. We present a new data set of density perturbation amplitudes derived from accelerometer measurements during aerobraking of the European Space Agency’s Trace Gas Orbiter. The obtained data set presents features found by three previous orbiters: the lower thermosphere polar warming in the winter hemisphere, and the lack of links between gravity wave activity and topography. In addition, the orbits allowed for demonstrating a very weak diurnal variability in wave activity at high latitudes of the southern winter hemisphere for the first time. The estimated vertical damping rates of gravity waves agree well with theoretical predictions. No clear anticorrelation between perturbation amplitudes and the background temperature has been found. This indicates differences in dissipation mechanisms of gravity waves in the lower and upper thermosphere.