Thermal Tides in the Martian Atmosphere near Northern Summer Solstice Observed by ACS/TIRVIM onboard TGO

TL;DR

This study analyzes thermal tides in the Martian atmosphere near northern summer solstice using TIRVIM data, revealing dominant diurnal and semi-diurnal tides with detailed wave mode decomposition and comparison to GCM predictions.

Contribution

It provides new observational insights into Martian atmospheric thermal tides during northern summer solstice, including wave mode analysis and model comparison.

Findings

Zonal mean temperature lower by 4-6K at ~100Pa

Dominant diurnal tide with 5K amplitude

Good overall agreement with GCM but with phase differences

Abstract

Thermal tides in the Martian atmosphere are analyzed using temperature profiles retrieved from nadir observations obtained by the TIRVIM Fourier-spectrometer, part of the Atmospheric Chemistry Suite (ACS) onboard the ExoMars Trace Gas Orbiter (TGO). The data is selected near the northern summer solstice at solar longitude (LS) 75{\deg}-105{\deg} of Martian Year (MY) 35. The observations have a full local time coverage, which enables analyses of daily temperature anomalies. The observed zonal mean temperature is lower by 4-6K at ~100Pa, but higher towards the summer pole, compared to the LMD Mars General Circulation Model (GCM). Wave mode decomposition shows dominant diurnal tide and important semi-diurnal tide and diurnal Kelvin wave, with maximal amplitudes of 5K, 3K, and 2.5K, respectively, from tens to hundreds of Pa. The results generally agree well with the LMD Mars GCM, but with noticeable earlier phases of diurnal (~1h) and semi-diurnal (~3h) tides.