Effective shear stress threshold on Mars from a global dune flux survey

Global circulation models (GCMs) can be used to assess sediment transport pathways on Mars surface (e.g. Rubanenko et al., 2023). This requires the knowledge of an effective shear stress threshold that, when used in conjunction with the GCM outputs, allows the prediction of potential sand fluxes. Flux seasonal variations in Nili Patera were estimated from large ripples displacements, allowing Ayoub et al. (2014) to calibrate an effective GCM shear stress threshold. Yet, fluxes derived from ripple migration are not representative of bulk sedimentary fluxes, which can be inferred for instance from dunes slip face advancements (Chojnacki et al., 2021). In addition, the seasonal impact of ice/frost in the mobility of sand on Mars, which is particularly relevant for polar regions that host the majority of dune fields, remains to be studied.We will report on an ongoing effort that seeks to use dune fluxes derived from long-term HiRISE observations of different sites and a GCM to 1) improve the calibration of a GCM effective shear stress threshold, and 2) estimate an ice thickness threshold needed to prevent sand motion on Mars. ReferencesAyoub, F., Avouac, J.-P., Newman, C. E., Richardson, M. I., Lucas, A., Leprince, S., Bridges, N. T. (2014). Threshold for sand mobility on Mars calibrated from seasonal variations of sand flux. Nature Communications, 5, 5096. https://doi.org/10.1038/ncomms6096Chojnacki, M., Vaz, D. A., Silvestro, S., Silva, D. C. A. (2021). Widespread Megaripple Activity Across the North Polar Ergs of Mars. Journal of Geophysical Research: Planets, 119. https://doi.org/10.1029/2021je006970Rubanenko, L., Gunn, A., Prez-Lpez, S., Fenton, L. K., Ewing, R. C., Soto, A., Laptre, M. G. A. (2023). Global Surface Winds and Aeolian Sediment Pathways on Mars from the Morphology of Barchan Dunes. 112. https://doi.org/10.1029/2022GL102