Atmospheric gravity waves play a crucial role in driving latitudinal air currents on the Red Planet, particularly at high altitudes, according to a new study by University of Tokyo planetary researchers.
This image from the Emirates Mars Mission shows Mars and its thin atmosphere. Image credit: UAESA / MBRSC / Hope Mars Mission / EXI / AndreaLuck.
“On Earth, large-scale atmospheric waves caused by the planet’s rotation, known as Rossby waves, are the primary influence on the way air circulates in the stratosphere, or the lower part of the middle atmosphere,” said University of Tokyo’s Professor Kaoru Sato, co-author on the study.
“But our study shows that on Mars, gravity waves have a dominant effect at the mid and high latitudes of the middle atmosphere.”
“Rossby waves are large-scale atmospheric waves, or resolved waves, whereas gravity waves are unresolved waves, meaning they are too fine to be directly measured or modeled and must be estimated by more indirect means.”
“Not to be confused with gravitational waves from massive stellar bodies, gravity waves are an atmospheric phenomenon when a packet of air rises and falls due to variations in buoyancy. That oscillating motion is what gives rise to gravity waves.”
Due to the small-scale nature of them and the limitations of observational data, planetary researchers have previously found it challenging to quantify their significance in the Martian atmosphere.
So Professor Sato and her colleagues turned to the Ensemble Mars Atmosphere Reanalysis System (EMARS) dataset, produced by a range of space-based observations over many years, to analyze seasonal variations up there.
“We found something interesting, that gravity waves facilitate the rapid vertical transfer of angular momentum, significantly influencing the meridional, or north-south, in the middle atmosphere circulations on Mars,” said study’s first author Anzu Asumi, a graduate student at the University of Tokyo.
“It’s interesting because it more closely resembles the behavior seen in Earth’s mesosphere rather than in our stratosphere.”
“This suggests existing Martian atmospheric circulation models may need to be refined to better incorporate these wave effects, potentially improving future climate and weather simulations.”
The team now plans to investigate the impact of Martian dust storms on atmospheric circulation.
“So far, our analysis has focused on years without major dust storms,” Professor Sato said.
“However, these storms dramatically alter atmospheric conditions, and we suspect they may intensify the role of gravity waves in circulation.”
“Our research lays the groundwork for forecasting Martian weather, which will be essential for ensuring the success of future Mars missions.”
The study appears in the Journal of Geophysical Research: Planets.
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Anzu Asumi et al. Climatology of the Residual Mean Circulation of the Martian Atmosphere and Contributions of Resolved and Unresolved Waves Based on a Reanalysis Dataset. Journal of Geophysical Research: Planets, published online March 6, 2025; doi: 10.1029/2023JE008137
