Subtropical Dust Storms and Downslope Wind Events

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Authors

Pokharel, Ashok K.
Kaplan, Michael L.
Fiedler, Stephanie

Issue Date

2017

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Article

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buoyancy , downslope winds , dust storms , subtropical|TKE , wind shear

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Abstract

We performed detailed mesoscale observational analyses and Weather Research and Forecasting (WRF) model simulations to study the terrain-induced downslope winds that generated dust-emitting winds at the beginning of three strong subtropical dust storms in three distinctly different regions of North Africa and the Arabian Peninsula. We revisit the Harmattan dust storm of 2 March 2004, the Saudi dust storm of 9 March 2009, and the Bodele Depression dust storm of 8 December 2011 and use high-resolution WRF modeling to assess the dynamical processes during the onset of the storms in more depth. Our results highlight the generation of terrain-induced downslope winds in response to the transition of the atmospheric flow from a subcritical to supercritical state in all three cases. These events precede the unbalanced adjustment processes in the lee of the mountain ranges that produced larger-scale dust aerosol mobilization and transport. We see that only the higher-resolution data sets can resolve the mesoscale processes, which are mainly responsible for creating strong low-level terrain-induced downslope winds leading to the initial dust storms.

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Citation

Pokharel, A. K., Kaplan, M. L., & Fiedler, S. (2017). Subtropical Dust Storms and Downslope Wind Events. Journal of Geophysical Research: Atmospheres, 122(19), 10,191–10,205. doi:10.1002/2017jd026942

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2169-897X

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