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

Thermal tides significantly influence Martian atmospheric dynamics and radiative transfer. However, the excitation mechanisms of non-migrating tides, exhibiting diverse spatial structures, remain poorly understood due to the limited number of observations. We investigated these tides using temperature observations from the Emirates Mars InfraRed Spectrometer (EMIRS) onboard the Emirates Mars Mission (EMM). The comprehensive local time coverage of the EMIRS data allows alias-free tidal mode decomposition, revealing detailed seasonal variability, spatial structure, and vertical propagation characteristics. We detect a terdiurnal westward-propagating wavenumber-1 (TW1) mode with amplitudes exceeding 1 K during a regional dust storm (C-storm) and characterize its alias-free structure in the lower atmosphere. The results demonstrate a robust link between the seasonal variations in tides and dust events. 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 atmospheric processes on Mars.