Diurnal Temperature Variations and Thermal Tides in the Martian Atmosphere before and during Regional Dust Storms Observed by EMIRS

Abstract

The Martian atmosphere experiences large diurnal variations due to its small thickness and low heat capacity. Driven by diurnal solar insolation and influenced by topography and radiative drivers (clouds and dust), diurnal temperature changes propagate from lower atmosphere into higher altitudes as forms of atmospheric tides. However, our understanding of diurnal variations in the Martian atmosphere is poor due to the lack of observations, especially those covering the entire planet and all local times, until recent. In its novelly designed high-altitude orbit, instruments onboard the Hope probe of the Emirates Mars Mission (EMM) could obtain a full geographic and local time coverage of Mars every 10 Martian days (Almatroushi et al., 2021). The Emirates Mars InfraRed Spectrometer (EMIRS, Edwards et al., 2021) observes surface temperature, temperature profile, dust content, water clouds, and water vapor in the lower atmosphere. Diurnal variations of such properties are derived on a planetary scale for the first time without significant gaps in local time or interference from seasonal changes. Such a rapid full planetary-scale coverage is ideal for investigating the fast-changing dust storms on Mars. In this talk, we present results of diurnal temperature variations and thermal tides before, during, and after several regional dust storms in Martian Year (MY) 36 and 37, and their coupling with dust and clouds. The results are also compared with numerical simulations by the Mars Planetary Climate Model (PCM), providing valuable information on physical processes controlling the diurnal climate of Mars. Almatroushi, H., AlMazmi, H., AlMheiri, N., AlShamsi, M., AlTunaiji, E., Badri, K., et al. (2021). Emirates Mars Mission Characterization of Mars Atmosphere Dynamics and Processes. Space Science Reviews, 217(8), 89. https://doi.org/10.1007/s11214-021-00851-6 Edwards, C. S., Christensen, P. R., Mehall, G. L., Anwar, S., Tunaiji, E. A., Badri, K., et al. (2021). The Emirates Mars Mission (EMM) Emirates Mars InfraRed Spectrometer (EMIRS) Instrument. Space Science Reviews, 217(7), 77. https://doi.org/10.1007/s11214-021-00848-