A comparative look at atomic oxygen and carbon dioxide neutral densities on Mars using data from the MAVEN satellite mission

Abstract

This thesis uses the level 2 limb scan data from the IUVS instrument onboard the MAVEN satellite to investigate the density distributions of atomic oxygen and carbon dioxide in the lower thermosphere of Mars. In addition to examining the density as a function of spatial position, the dependencies on SZA and local time are also inspected. The data used in the study are during the time interval between October 2014 and June 2018.

Results of this study show that the density of carbon dioxide, the major species on Mars, is predominantly driven by typical atmospheric forces related to solar irradiation absorption. An atmosphere wave 2 structure appears clearly when examining the average density variation over longitudes, and an inverse relationship between the solar zenith angle and density occurs above 50 degrees SZA. During the spring and autumn equinox, the density distribution peaks about the equatorial region, and the dependence on local time shows that the density peaks in the afternoon. However, the same studies with the atomic oxygen data show more variations at all altitudes, which lead to the conclusion that oxygen is being strongly affected by other driving forces even in the thermosphere as low as 120 km. The study of carbon dioxide and atomic oxygen will contribute to primary knowledge of the Martian thermosphere and improve understanding of the driving forces that affect these species.