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TOPIC: Saltation

Blobrana

L

Posts: 131433

Date: Jan 23 14:01 2012

Aeolian saltation	Permalink

Title: The physics of wind-blown sand and dust Authors: Jasper F. Kok, Eric J. R. Parteli, Timothy I. Michaels, Diana Bou Karam The transport of dust and sand by wind is a potent erosional force, creates sand dunes and ripples, and loads the atmosphere with suspended dust aerosols. This article presents an extensive review of the physics of wind-blown sand and dust on Earth and Mars. Specifically, we review the physics of aeolian saltation, the formation and development of sand dunes and ripples, the physics of dust aerosol emission, the weather phenomena that trigger dust storms, and the lifting of dust by dust devils and other small-scale vortices. We also discuss the physics of wind-blown sand and dune formation on Venus and Titan. Read more (4950kb, PDF) __________________

Blobrana

L

Posts: 131433

Date: Mar 4 20:59 2010

Mars Dunes	Permalink

Mars Dunes New studies of ripples and dunes shaped by the winds on Mars testify to variability on that planet, identifying at least one place where ripples are actively migrating and another where the ripples have been stationary for 100,000 years or more. Patterns of dunes and the smaller ripples present some of the more visually striking landforms photographed by cameras orbiting Mars. Investigations of whether they are moving go back more than a decade. Read more __________________

Blobrana

L

Posts: 131433

Date: Jan 28 23:32 2010

Saltation	Permalink

Title: Analytical calculation of the minimum wind speed required to sustain wind-blown sand on Earth and Mars Authors: Jasper F. Kok The wind-driven hopping motion of sand grains, known as saltation, forms dunes and ripples and ejects fine dust particles into the atmosphere on both Earth and Mars. While the wind speed at which saltation is initiated, the fluid threshold, has been studied extensively, the wind speed at which it is halted, the impact threshold, has been poorly quantified for Mars conditions. We present an analytical model of the impact threshold, which we show to be in agreement with measurements and recent numerical simulations for Earth conditions. For Mars conditions, we find that the impact threshold is approximately an order of magnitude below the fluid threshold, in agreement with previous studies. Saltation on Mars can thus be sustained at wind speeds an order of magnitude less than required to initiate it, leading to the occurrence of hysteresis. These results confirm earlier simulations with a detailed numerical saltation model, and have important implications for the formation of sand dunes, ripples, and dust storms on Mars. Read more (372kb, PDF) __________________

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