Retrieval of CO2 and N2 in the Martian thermosphere using dayglow observations by IUVS on MAVEN. Issue 21 (5th November 2015) - Evans, J. S.
Abstract: We present direct number density retrievals of carbon dioxide (CO2 ) and molecular nitrogen (N2 ) for the upper atmosphere of Mars using limb scan observations during October and November 2014 by the Imaging Ultraviolet Spectrograph on board NASA's Mars Atmosphere and Volatile EvolutioN (MAVEN) spacecraft. We use retrieved CO2 densities to derive temperature variability between 170 and 220 km. Analysis of the data shows (1) low‐mid latitude northern hemisphere CO2 densities at 170 km vary by a factor of about 2.5, (2) on average, the N2 /CO2 increases from 0.042 ± 0.017 at 130 km to 0.12 ± 0.06 at 200 km, and (3) the mean upper atmospheric temperature is 324 ± 22 K for local times near 14:00. Key Points: Retrieved CO2 densities at 170 km vary by a factor of about 2.5 On average, N2 /CO2 increases from 4% at 130 km to 12% at 200 km Mean Martian upper atmospheric temperature over the sampled time frame is 324 {±} 22 K