Presentation #203.09 in the session The Martian Upper Atmosphere.
Bimonthly campaigns of nightside stellar occultation observations carried out by the Imaging Ultraviolet Spectrograph (IUVS) instrument on board the MAVEN spacecraft allow us to retrieve vertical profiles of Martian ozone abundance using an ozone absorption band centred at 255 nm (the ‘Hartley Band’). At the same time, systematic offsets in spectral absorption and slope between 200 and 300 nm respectively allow us to constrain vertical profiles of aerosol optical depth together with the size distribution of sub-micron aerosol particles to first order. The spatial and temporal distribution of these observations allow us to search for longitudinal variations in these profiles that can be fully decoupled from other seasonal, latitudinal and diurnal variations. We expand on the work of Gröller et al. (2018, J. Geophys. Res. Planets 123, 1449–1483) to produce vertical profiles of mesospheric ozone local density covering a period from Martian years 32 to 36, filtering out false detections using an approach based on Teanby et al. (2019, Icarus 319, 86–98). Although we find that longitudinal variations in ozone are generally small, we do find some significant perturbations particularly in southern mid-latitudes, possibly a result of the presence of a polar vortex, as well as at latitudes in which significant longitudinal variations of aerosol are present. We also monitor the presence of detached aerosol layers in the data, and observe longitudinal wave structures together with a class of aerosol layers that are only present during perihelion.