High-Latitude Zonal Jets in the Martian Upper Atmosphere Driven by Non-Orographic Gravity Waves

TL;DR

This study combines observations and simulations to analyze how non-orographic gravity waves influence high-latitude zonal jets in Mars's upper atmosphere, revealing their role in modulating atmospheric circulation.

Contribution

It provides the first combined observational and modeling evidence of gravity wave impacts on Martian high-latitude jets, emphasizing wave-mean flow interactions.

Findings

Gravity waves cause jet accelerations of up to 280 m/s.

Wave saturation and wind filtering drive momentum divergence of 1,300 m/s/sol.

GWs modulate jets in the hemisphere with descending Hadley Cell branches.

Abstract

We investigate thermosphere responses to non-orographic gravity waves (GWs) using wind measurements from the Neutral Gas and Ion Mass Spectrometer onboard the Mars Atmosphere and Volatile EvolutioN mission, alongside simulations from the Mars Planetary Climate Model. We focus on zonal jets in high-latitude regions of the upper atmosphere. Jet acceleration and deceleration (280 m/s ) arise from momentum divergence (1,300 m/s/sol ) driven by wave saturation and wind filtering. Simulations and observations indicate that GWs modulate these jets in the hemisphere associated with the descending branches of the Hadley Cell, due to the absence of wave critical layers in the middle atmosphere. Interactions between GWs and the mean flow can shape the circulation and dynamics of the upper atmosphere of Mars.