Non-Migrating Thermal Tides in the Martian Lower Atmosphere observed by EMM/EMIRS

Abstract

Thermal tides significantly influence Martian atmospheric dynamics and radiative transfer, yet the excitation mechanisms of non-migrating tides, exhibiting diverse spatial structures, remain poorly understood due to observational limitations. We investigate these tides using temperature observations from the Emirates Mars InfraRed Spectrometer (EMIRS) onboard the Emirates Mars Mission (EMM). Leveraging EMM’s comprehensive local-time coverage allows alias-free tidal mode decomposition, revealing detailed seasonal variability, spatial structure, and vertical propagation characteristics. Notably, we detect a previously unrecognized terdiurnal westward-propagating wavenumber-1 tidal mode, exhibiting amplitudes exceeding 1 K during a regional dust storm event. Results demonstrate a robust link between tidal seasonal variations and dust activity. Observed vertical phase shears and partial wave reflections imply significant nonlinear interactions and feedback processes within the dusty Martian troposphere. These findings underscore the critical influence of aerosols on tidal dynamics, enhancing our understanding of broader atmospheric processes on Mars.