Scientists have now roughly determined the global wind patterns on Mars, based on the orientation of one type of crescent-shaped dune called barchan dunes.

The global map above and the north pole map to the right come from figure 2 of the paper. The colored letters indicate the location of additional close-up images. On the polar map Olympia Undae is Mars’ largest dune field. From the abstract:

Crescent-shaped sand dunes are prevalent across the deserts of Mars. Here, we use the physical relationship between the shape of these dunes and the winds that form them to infer the directions of surface winds on Mars on a global scale. We find that dunes typically adhere to the global circulation patterns of Mars’ atmosphere, and that local topographic winds are mostly important in areas with high topographic roughness such as inside deep impact craters. Our global wind map can serve to calibrate numerical climate models, which in turn can help us learn about the recent and modern-day climate of Mars.

The arrows on both maps indicate the direction of the prevailing winds. This data will also help clarify the orientation of many surface features seen by Mars Reconnaissance Orbiter’s high resolution camera. This data also helps explain why the lander InSight never got a burst of wind to clear the dust from its solar panels, while the rovers Spirit and Opportunity did. The rovers were located in regions with clear prevailing winds. InSight was not.