DIX Planetary Science Seminar

Thermal tides are planetary-scale harmonic responses driven by diurnal solar forcing and influenced by planetary topography. Excited by solar heating absorbed by the atmosphere and energy exchange with surface, thermal tides grow in Martian atmosphere. These tides usually have large amplitudes due to the low heat capacity of Martian atmosphere, and dominate its diurnal variations. In this talk, I will present results of the analysis of thermal tides in the Martian atmosphere during aphelion season using temperature profiles retrieved using infrared spectra obtained by the TIRVIM Fourier-spectrometer, part of the Atmospheric Chemistry Suite (ACS) onboard the ExoMars Trace Gas Orbiter (TGO) and the Emirates Mars InfraRed Spectrometer (EMIRS) instrument onboard the Emirates Mars Mission (EMM) Hope spacecraft. Design of non-Sun-synchronous orbits of these spacecrafts enable the analysis of diurnal temperature variations in Martian atmosphere with full local time coverage within a short period of time. Wave mode decomposition is applied to these diurnal variations, and amplitudes of tide modes are derived. The results show good agreements with predictions derived using the Mars Planetary Climate Model (PCM), previously known as the Laboratoire de Météorologie Dynamique (LMD) Mars Global Circulation Model (GCM), except for noticeable differences in tide phases.