Windsysteme und Dünenbildung im Galekrater, Mars
Zusammenfassung der Projektergebnisse
The goal of this project was to model wind systems and sediment transport in Gale Crater, Mars, with consideration of this crater’s strong local topography. While previous models were designed to investigate dunes over a flat horizontal ground at the bedform scale, this project has paved the way toward regional geomorphodynamic simulations of Aeolian sediment landscapes, with consideration of real complex topography and concatenated wind patterns. Gale Crater provides an excellent laboratory for investigating topographic effects on regional transport patterns, given its central mountain (Aeolis Mons) that rises 5.5 km high from the crater floor. By means of CFD simulations, we identify areas to the east and west of Aeolis Mons in which wind speed is below threshold for sand transport without regard of the incident wind direction, i.e., such regions may play an important role for sand deposition. Moreover, simulations with northerly winds — considered primary with regard to Aeolian processes in Gale Crater — produce funnelling of the wind flow around Aeolis Mons’ flanks. This finding is consistent with the observed main orientation of Western and Eastern dune fields in Gale crater and corroborates the main thesis of this proposal, that topography-induced flow patterns are crucial to understand Gale crater dune fields. Furthermore, while no substantial recirculation is observed in the mount wake due to northely winds, simulations using southerly winds yield wind speeds that could be substantial enough to entrain sediments near the southern rim of Gale crater. Despite the initial progress achieved in this project, there is a long road toward a reliable, fullscale model of Gale crater sedimentary processes. A better understanding of the threshold wind speeds for sand transport on Mars is needed to correctly estimate the sand fluxes from predicted shear stresses throughout Gale crater. This threshold may be reduced substantially by tribocharging (as we found from modelling in this project), while thermal creep in the Martian subsoil may further decrease the minimal wind speed for transport initiation on Mars. We also developed a model for the angle of repose as a function of gravity, which predicts slightly steeper slopes of dune slip faces on Mars compared to Earth. However, this model should be now improved by adding thermal creep and electrostatics. Moreover, our project should be continued by incorporating katabatic winds, unsteady flow patterns over dunes and the effect of the Martian thick viscous sublayer on the morphodynamic model of Martian dunes. These extensions are crucial to resolve sand flux in the transitional flow regime and to model dunes on Mars and other celestial bodies of our Solar System, as for instance the methane ice dune fields that surround Pluto’s Al-Idrisi Montes. Overall, the model development performed in this project finds application for Aeolian process modelling on our own planet, and shall be now used to improve the quantitative assessment of climate change and anthropogenic effects on Earth’s sand desert processes at regional scale.
Projektbezogene Publikationen (Auswahl)
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Planetary Aeolian Geomorphology. Aeolian Geomorphology, 261-286. Wiley.
Bourke, Mary C.; Balme, Matthew; Lewis, Stephen; Lorenz, Ralph D. & Parteli, Eric
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Lifting of Tribocharged Grains by Martian Winds. The Planetary Science Journal, 2(6), 238.
Kruss, Maximilian; Salzmann, Tim; Parteli, Eric; Jungmann, Felix; Teiser, Jens; Schönau, Laurent & Wurm, Gerhard
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Physics and Modeling of Wind-Blown Sand Landscapes. Treatise on Geomorphology, 20-52. Elsevier.
Parteli, Eric J.R.
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Wind shear stress over Gale Crater, Mars, from CFD simulations . Copernicus GmbH.
Jankowiak, Joel; Seybold, Hansjörg; Tirsch, Daniela & Parteli, Eric
