Are Mars Aeolian Features Controlled by the Strongest Winds? A Mesoscale Modelling Investigation

Mars aeolian studies commonly compare mapped surface features such as dunes, ripples, and wind streaks with atmospheric model outputs in order to infer formative wind regimes. In practice, these comparisons are often based on only the strongest modelled winds, typically the upper 5% of wind speeds, under the assumption that sediment transport and streak formation are dominated by rare high-wind events. However, the extent to which this assumption is universally valid across different Martian environments remains poorly tested. Here, we investigate whether restricting analyses to the top 5% of modelled winds provides the most representative comparison with observed aeolian orientations across three contrasting regions on Mars: Mawrth Vallis, Ares Vallis, and Syrtis Major.

We use mesoscale simulations produced with the Laboratoire de Météorologie Dynamique Mars Mesoscale Model [1], forced using the Open access to Mars Assimilated Remote Soundings (OpenMARS) assimilated atmospheric boundary conditions [2], and compare modelled wind direction distributions against mapped dune slip faces and wind streaks derived from CTX imagery [3]. We quantify correspondence between observed and modelled directional distributions using Earth Mover’s Distance metrics [4]. Our results suggest that the common approach of focusing on the strongest modelled winds is broadly appropriate at two of the study sites, where the upper tail of the wind distribution provides the closest agreement with mapped aeolian orientations. However, results from the third site reveal a substantially more complex relationship between surface feature orientation and atmospheric circulation. The complexity of the local environment appears to exert a stronger control on the observed aeolian record, implying that site-specific atmospheric dynamics must be considered when interpreting surface wind indicators.

These findings suggest that while threshold-based approaches remain useful, applying a universal “fastest winds create the landforms” assumption across Mars may not always be appropriate, oversimplifying the relationship between atmospheric circulation and aeolian landscape evolution.

[1] Spiga, A. and Forget, F. (2009) JGR-Planets, 114(E2) [2] Holmes, J. A. et al. (2020) Planet. Space Sci., 188, 104962 [3] Dickson, J. L. et al. (2024) Earth and space Sci., 11(7) [4] Rubner, Y., Tomasi, C., and Guibas, L. J. (2000) Int. J. Comput. Vis., 40(2), 99–121.