Seasonal and Diurnal Variation in Vertical Profiles of the Martian Nitric Oxide Nightglow Layer

The nitric oxide (NO) nightglow is a recombination reaction rate which traces flux between from the nightside Martian thermosphere to the mesosphere. Brighter emission occurs where descending air brings molecules deeper into the mesosphere, so we can use the reaction rate as a tracer of the dynamics between Mars’ thermosphere and mesosphere. We derive vertical profiles of NO nightglow brightness from limb-scan spectra observed by the Imaging Ultraviolet Spectrograph (IUVS) on the Mars Atmosphere and Volatile Evolution (MAVEN) spacecraft. This data set has broad seasonal, latitudinal, and local-time coverage, allowing us to comprehensively characterize the behavior of the nightglow layer by latitude, local time, and season and even analyze waves and tidal structures, greatly expanding the results of previous limb scan studies. We also compare these observations to simulations from the LMD-MGCM and corresponding insights into altitude- and temporal-dependence of temperature, downwelling wind velocity, and atomic N and O densities.