Drivers of Irregular Spatio-temporal Variations of Far Ultraviolet Dayglow at Mars Observed by EMM EMUS
Abstract
The Emirates Mars Ultraviolet Spectrometer (EMUS) onboard the Emirates Mars Mission observes the Martian dayglow at far and extreme ultraviolet wavelengths. EMUS disk observations show expected variations with emission angle, and a dawn-dusk asymmetry attributed to local time differences in advection, but also show unexpected variations in O I 130.4 nm, O I 135.6 nm, and CO Fourth Positive Group disk emission features. Variations in the brightness of these dayglow features are observed with irregular shapes occurring in approximately 25% of the disk images. These variations display local time and hemispheric asymmetry in their occurrence rates. England et al. (2022) examined the spatial structure, occurrence, and spectral characteristics of these variations and suggested that they are associated with variations in composition and photoelectron flux. We further investigate the potential drivers for the unexpected variations in EMUS disk observations by incorporating vertical profiles of densities and temperatures retrieved from limb scan observations by the Imaging Ultraviolet Spectrograph (IUVS) onboard MAVEN. We use IUVS dayglow limb scan observations, retrieved densities, and temperatures to identify signatures of dynamics, including planetary waves and circulation, that correlate with unexpected variations in EMUS disk observations. We also investigate correlations between variations in inert species (N2, Ar) and variations observed in photochemically active species (O and CO).
- Publication:
-
AGU Fall Meeting Abstracts
- Pub Date:
- December 2022
- Bibcode:
- 2022AGUFM.P42F2457E