Analytical calculation of the minimum wind speed required to sustain wind-blown sand on Earth and Mars - Astrophysics > Earth and Planetary AstrophysicsReport as inadecuate




Analytical calculation of the minimum wind speed required to sustain wind-blown sand on Earth and Mars - Astrophysics > Earth and Planetary Astrophysics - Download this document for free, or read online. Document in PDF available to download.

Abstract: The wind-driven hopping motion of sand grains, known as saltation, formsdunes and ripples and ejects fine dust particles into the atmosphere on bothEarth and Mars. While the wind speed at which saltation is initiated, the fluidthreshold, has been studied extensively, the wind speed at which it is halted,the impact threshold, has been poorly quantified for Mars conditions. Wepresent an analytical model of the impact threshold, which we show to be inagreement with measurements and recent numerical simulations for Earthconditions. For Mars conditions, we find that the impact threshold isapproximately an order of magnitude below the fluid threshold, in agreementwith previous studies. Saltation on Mars can thus be sustained at wind speedsan order of magnitude less than required to initiate it, leading to theoccurrence of hysteresis. These results confirm earlier simulations with adetailed numerical saltation model, and have important implications for theformation of sand dunes, ripples, and dust storms on Mars.



Author: Jasper F. Kok

Source: https://arxiv.org/



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