Astronomers compare Mars's weather patterns with those on Earth. (© Artsiom P - stock.adobe.com)
In a nutshell
• Tiny atmospheric ripples called gravity waves, not large planetary waves, are the main drivers of Mars’s weather patterns, especially in the middle and upper atmosphere.
• Mars’s atmospheric circulation resembles Earth’s mesosphere (50-85 km up) rather than our lower atmosphere, with winds reaching speeds of 63 mph during Martian winter.
• This discovery will help scientists create more accurate weather forecasting models for Mars, which is crucial for the safety and success of future exploration missions.
TOKYO — How’s the weather up there? On Mars, weather forecasts haven’t always been right at our fingertips. Now, recent research from the University of Tokyo has upended what scientists thought they knew about the Red Planet’s atmosphere, revealing that its circulation has more in common with Earth’s upper atmosphere than our everyday weather.
The Surprising Drivers of Martian Weather
Research published in the Journal of Geophysical Research: Planets recently revealed something unexpected: tiny atmospheric waves play a huge role in how air moves around Mars. This discovery challenges what scientists previously thought about how the Red Planet’s atmosphere works.
“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. But our study shows that on Mars, gravity waves (GWs) have a dominant effect at the mid and high latitudes of the middle atmosphere,” says study author Kaoru Sato, a professor from the University of Tokyo, in a statement.
What are gravity waves? Despite their name, they’re not the space-time ripples Einstein talked about. They’re waves that form when air rises and falls because of buoyancy. Think of them as ripples in the atmosphere. On Earth, we see their effects in cloud patterns that look like ripples on water.
These small waves were previously overlooked because they’re hard to detect and measure with current technology. Yet they appear to be driving Mars’s weather patterns in significant ways.
How Mars Weather Actually Works
The thermal impact of dust storms on Mars is significant, and is thought to play a similar role to that of water vapor in Earth’s atmosphere. (CREDIT:
NASA CC0)
The researchers studied what scientists call residual mean circulation, which describes how air slowly moves across a planet’s atmosphere over long timescales. Unlike daily weather patterns, this circulation helps transport heat and gases across latitudes, shaping seasonal and long-term climate trends. Gravity waves appear to be a dominant driver of this circulation.
“It’s interesting because it more closely resembles the behavior seen in Earth‘s mesosphere rather than in our stratosphere,” says study author Anzu Asumi, a University of Tokyo graduate student.
The team analyzed data from the Ensemble Mars Atmosphere Reanalysis System (EMARS), which combines observations from Mars spacecraft with computer models. They specifically looked at four Martian years of data, carefully avoiding periods with global dust storms that would scramble the normal patterns.
They found that during winter and summer, air flows from the summer hemisphere toward the winter hemisphere at certain heights. While this general pattern resembles Earth’s atmospheric circulation, there are key differences: Mars’s circulation covers more territory and moves much faster than Earth’s.
In the Northern Hemisphere winter, they recorded north-south winds moving northward at about 63 mph at certain altitudes. During the Northern Hemisphere summer, southward winds reached about 43 mph, still substantial but noticeably weaker than the winter flows.
Why This Matters for Mars Exploration
NASA’s Perseverance Mars rover took this selfie in July 2024. (Credit: NASA/JPL-Caltech/MSSS)
“Looking ahead, we plan to investigate the impact of Martian dust storms on atmospheric circulation. So far, our analysis has focused on years without major dust storms,” says Sato. “However, these storms dramatically alter atmospheric conditions, and we suspect they may intensify the role of GWs in circulation. Our research lays the groundwork for forecasting Martian weather, which will be essential for ensuring the success of future Mars missions.”
Every new discovery about Mars reminds us how much we still have to learn about our solar system neighbors. The recognition that gravity waves, not large planetary waves, drive Martian weather highlights the dangers of assuming other planets work just like Earth. For mission planners and future explorers, this deeper understanding of Mars’s atmospheric behavior isn’t just academically interesting; it’s potentially life-saving information. Accurate forecasting could help mission planners avoid dangerous conditions and better interpret atmospheric data collected on the planet. The Red Planet’s weather forecast has just become more readable, though no less alien.
Paper Summary
Methodology
The researchers used the EMARS dataset, which combines spacecraft observations with atmospheric models. They focused on four Martian years (MY 29-32), deliberately excluding periods with global dust storms. Using a framework called the transformed Eulerian mean equation system, they analyzed circulation patterns and distinguished between large-scale “resolved waves” and smaller “unresolved waves.” Their innovative approach allowed them to indirectly estimate the effects of small-scale gravity waves that couldn’t be measured directly.
Results
The study revealed that Mars’s atmospheric circulation varies drastically throughout its annual cycle. During winter and summer, strong residual mean meridional flows (north-south winds) travel from the summer hemisphere to the winter hemisphere at middle atmosphere altitudes (30-40 km). In Northern Hemisphere winter, these northward winds reached 28.5 m/s (63 mph), while in Northern Hemisphere summer, southward winds peaked at 19.2 m/s (43 mph). Most significantly, small-scale gravity waves, not large planetary waves, were found to be the primary drivers of this circulation, especially above 50 km altitude.
Limitations
The study’s approach for estimating unresolved wave forcing only works in off-equatorial regions where angular momentum contours are continuous from surface to upper atmosphere. The EMARS dataset has limited spatial resolution, meaning some atmospheric phenomena remain undetected. The analysis focused only on periods without global dust storms, leaving questions about how these major events affect circulation patterns. While the research identified the importance of gravity waves, it couldn’t determine their exact origins or classify them into specific types.
Discussion and Takeaways
This research fundamentally reshapes our understanding of Mars’s atmospheric dynamics. The Martian atmosphere behaves more like Earth’s mesosphere than its stratosphere, with small-scale waves being the primary circulation drivers. This has significant implications for Mars exploration, as accurate weather prediction will be crucial for mission planning and safety. Current atmospheric models might need to be improved to better account for gravity wave effects. The findings open avenues for future research, particularly into how dust storms affect atmospheric circulation patterns.
Funding and Disclosures
The research was supported by the Japan Society for the Promotion of Science (Grant 22H00169). The researchers used the libraries of GFD-DENNOU Club for data analyses and figure production. No conflicts of interest were reported.
Publication Information
The study titled “Climatology of the Residual Mean Circulation of the Martian Atmosphere and Contributions of Resolved and Unresolved Waves Based on a Reanalysis Dataset” was authored by Anzu Asumi, Kaoru Sato, and Masashi Kohma from the University of Tokyo, and Yoshi-Yuki Hayashi from Kobe University. It was published in the Journal of Geophysical Research: Planets on March 6, 2025.