Temporal variations of the atomic oxygen on Mars' upper atmosphere derived from the O I 130.4 nm triplet observed by MAVEN/IUVS

The Imaging Ultraviolet Spectrograph (IUVS) aboard the Mars Atmosphere and Volatile EvolutioN (MAVEN) mission has systematically observed the Martian oxygen exosphere for nearly two Martian years now. The OI 130.4 nm optically thick line, observed at the dayside, is mainly produced by resonant scattering and photoelectron impact on atomic oxygen. Its study provides unprecedented information on the oxygen content of the Martian upper atmosphere. Atomic oxygen, produced by the photodissociation of the atmospheric carbon dioxide, becomes the main neutral species in the upper thermosphere and lower exosphere. This species is a key species for numerous physical processes in the Martian upper atmosphere (heating balance, dynamics, ions composition, escape). In this presentation, we will report the temporal variations of the oxygen density derived during several periods of observations from MAVEN/IUVS 130.4 nm line in thermosphere and lower exosphere from forward comparisons between observations and simulations.