Seasonal variability in winds in the north polar region of Mars

• Published in: Icarus (New York, N.Y. 1962) N.Y. 1962), 2018-07, Vol.308, p.188-196
• Main Authors: Smith, Isaac B., Spiga, Aymeric
• Format: Article
• Language: English
• Subjects: Sciences of the Universe
• ISSN: 0019-1035; 1090-2643
• DOI: 10.1016/j.icarus.2017.10.005

•We provide 3-day polar-focused mesoscale simulations from northern spring to summer at many dates.•We extract wind speed and directions to compare to atmospheric phenomena and dune orientations.•We conclude that the 3 day simulations are sufficient to explain the majority of phenomena, including cloud presence and timing and dune movement. Surface features near Mars’ polar regions are very active, suggesting that they are among the most dynamic places on the planet. Much of that activity is driven by seasonal winds that strongly influence the distribution of water ice and other particulates. Morphologic features such as the spiral troughs, Chasma Boreale, and prominent circumpolar dune fields have experienced persistent winds for several Myr. Therefore, detailing the pattern of winds throughout the year is an important step to understanding what processes affect the martian surface in contemporary and past epochs. In this study, we provide polar-focused mesoscale simulations from northern spring to summer to understand variability from the diurnal to the seasonal scales. We find that there is a strong seasonality to the diurnal surface wind speeds driven primarily by the retreat of the seasonal CO2 until about summer solstice, when the CO2 is gone. The fastest winds are found when the CO2 cap boundary is on the slopes of the north polar layered deposits, providing a strong thermal gradient that enhances the season-long katabatic effect. Mid-summer winds, while not as fast as spring winds, may play a role in dune migration for some dune fields. Late summer wind speeds pick up as the seasonal cap returns.