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ARS Home » Plains Area » Las Cruces, New Mexico » Range Management Research » Research » Publications at this Location » Publication #332610
Title: A numerical study on dust devils with implications to global dust budget estimates

Author
item KLOSE, MARTINA - New Mexico State University
item SHAO, YAPING - University Of Cologne

Submitted to: Aeolian Research
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 5/12/2016
Publication Date: 9/1/2016
Publication URL: http://handle.nal.usda.gov/10113/5859842
Citation: Klose, M., Shao, Y. 2016. A numerical study on dust devils with implications to global dust budget estimates. Aeolian Research. 22:47-58.

Interpretive Summary: Dust devils are small dust carrying vortices. They occur frequently on Earth and Mars, but their contributions to the terrestrial and martian dust budget are so far not well quantified. Due to their complicated flow-structure, the understanding and estimation of dust emission in dust devil is particularly difficult. Here, we use a high-resolution modeling technique (large-eddy simulation) together with a novel dust emission scheme that represents the entrainment of dust by aerodynamic forces. We show that large parts of the dust emission in dust devils can be explained by aerodynamic entrainment. Based on the numerical simulations, we introduce a method to estimate the number of dust devils and the amount of dust they transport globally. In contrast to earlier attempts, which used measurements of dust fluxes in individual dust devils, our method includes, for the first time, surface dust emission of a dust devil population.

Technical Abstract: The estimates of the contribution of dust devils (DDs) to the global dust budget have large uncertainties because the dust emission mechanisms in DDs are not yet well understood. In this study, a large-eddy simulation model coupled with a dust scheme is used to investigate DD dust entrainment. DDs are identified from the simulations using various threshold values for pressure drop and vorticity in the DD center. A vortex-tracking algorithm is presented, which automatically detects and tracks vortices based on different pressure drop and vorticity criteria. The results show that DD dust lifting can be largely explained by convective turbulent dust emission. DD dust entrainment varies strongly between individual DDs even for similar atmospheric conditions, but the maximum emissions are determined by atmospheric stability. By relating DD emission and counts to the Richardson number, we propose a new and simple method to estimate regional and global DD dust transport.