The role of mineral aerosols in shaping the regional climate of West Africa
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Eltahir_The role of mineral aerosols.pdf
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Author(s)
Eltahir, Elfatih A. B.
Marcella, Marc Pace
Date Issued
November 2013
Journal
Journal of Geophysical Research: Atmospheres
Publisher
American Geophysical Union (AGU)
Citation
Marcella, Marc P., and Elfatih, A. B. Eltahir. “The Role of Mineral Aerosols in Shaping the Regional Climate of West Africa: MINERAL AEROSOLS OVER WEST AFRICA.” Journal of Geophysical Research: Atmospheres 119.10 (2014): 5806–5822. © 2013 American Geophysical Union
Version
Final published version
Abstract
This article examines the role of mineral aerosols in the regional climate of West Africa. Analysis is completed by comparing two 30 year simulations using a regional climate model (RegCM3-IBIS). The two simulations are identical in structure except one includes the representation of mineral aerosols via a fully coupled radiatively interactive dust emissions and aerosol tracer model; the other simulation does not. To discern the impact of dust on West Africa's climate, comparisons are made between the two simulations' surface climatology as well as atmospheric dynamics. It is found that RegCM3-IBIS and its dust model perform well in simulating the temporal and spatial distributions of mineral aerosols over the Sahel and Sahara. Consistent with previous studies over the region, RegCM3-IBIS simulates high-dust loading over the region (aerosol optical depth of 0.5–1.1), which results in significant incident shortwave radiation attenuation (25–50 W/m2) and temperature cooling (0.5°C–1.25°C). Depending on the underlying surface brightness, the top of atmosphere net radiative forcing may be positive (bright desert surfaces) or negative (dark, vegetated surface) with important implications on surface temperature cooling. Here it is proposed that the effects of dust on West African rainfall are distinctly different across the ocean-land border and the desert border region of the Sahel/Sahara. Nevertheless, in both regions, the change in rainfall is less than 10% of the total annual values. Therefore, this work concludes that the current, observed, dust loading over West Africa does not significantly affect rainfall via changes in the radiation budget. However, it is important to note that this work does not include mineral aerosol effects on sea surface temperatures, which may be significant in influencing the results.
MIT Department
Massachusetts Institute of Technology. Department of Civil and Environmental Engineering
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Article is made available in accordance with the publisher's policy and may be subject to US copyright law. Please refer to the publisher's site for terms of use.
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DOI of Published Version
https://doi.org/10.1002/2012jd019394
