ISBN 978-3-8439-4705-3

978-3-8439-4705-3, Reihe Physik

Pia Krause
Upper Atmospheric Thermal Properties of Venus - Investigation of non-LTE CO2 Emission Lines using Ground-Based Mid-Infrared Heterodyne Spectroscopy

229 Seiten, Dissertation Universität Köln (2020), Softcover, A5

Zusammenfassung / Abstract

Ground-based heterodyne spectroscopy of C02 at mid-infrared wavelengths is a powerful tool to study temperatures and the dynamical behavior of the atmospheres of terrestrial planets. Mesospheric non-local thermodynamic equilibrium (non-LTE) emission of C02 near 10mum is observed in the Venusian atmosphere to determine temperatures at a pressure of 1mubar. The kinetic temperature cab be calculated from the width of the observed lines and is a good proxy for the physical temperature of the emitting gas as long as stimulated emission is negligible.

The heterodyne receivers THIS and HIPWAC have observed Venus during several campaigns in the past decade resulting in a comprehensive set of wind and temperature data. The data presented in this thesis are temperature measurements derived between 2007 and 2015. A total of 319 individual observations were performed in 11 campaigns with an excellent coverage of the Venusian dayside. For the first time, the global thermal structure of the transition region was probed with a spatial resolution of a few degrees only covering an extended time range. The temperatures obtained with infrared heterodyne spectroscopy are discussed in terms of global dayside thermal structure, short-, mid- and longterm changes in mesospheric temperatures, as well as the thermal structure of the terminator region. Furthermore, the infrared heterodyne results are compared to other observing methods and existing general circulation models.