Dust-raising in the dustiest place on earth
Warren, A. and Chappell, A. and Todd, M.C. and Bristow, Charlie S. and Drake, N. and Engelstaedter, S. and Martins, V. and M'Bainayel, S. and Washington, R. (2007) Dust-raising in the dustiest place on earth. Geomorphology 92 (1-2), 25 - 37. ISSN 0169-555X.
The Bodélé in northern Chad is the dustiest place on earth. It is dusty because of the co-location of strong near-surface winds and a large exposure of low-density, friable diatomite. Data are reported from three kinds of observation on dust generation in the Bodélé: (a) two automatic weather stations and pilot balloon tracking, complemented with reanalysis data, measuring and estimating wind velocities; (b) sun-photometers, measuring atmospheric dust concentrations; (c) a vacuum-pump dust sampler and an array of MWAC sediment samplers, measuring in-situ sediment transport. With these data, we develop four hypotheses about dust generation: (1) the pulsing of dust output from the Bodélé depends primarily on the varying strength of a Low Level Jet (LLJ); i.e., at this scale, dust production is transport-limited; (2) the most prolific mechanism of dust production is the breakdown of saltating diatomite flakes as they collide with each other and with the surface; (3) disturbance of flow around the large barchans, particularly turbulence and convergence on their “horns”, is a major contributor to dust production, i.e., the dunes are “dust-mills”; (4) in consequence, dust production is localised within the main exposure of diatomite to places where there are the most dunes, as on the eastern and northern fringes of the exposure.
|Keyword(s) / Subject(s):||Low level jet, transport-limitation, self-abrasion, dune-included turbulence, Bodélé, Chad|
|School:||Birkbeck Schools and Departments > School of Science > Earth and Planetary Sciences|
|Date Deposited:||04 Aug 2011 09:38|
|Last Modified:||17 Apr 2013 12:21|
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