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Response of the Water Cycle of West Africa and Atlantic to Radiative Forcing by Saharan DustThe responses of the atmospheric water cycle and climate of West Africa and the Atlantic to radiative forcing of Saharan dust are studied using the NASA finite volume general circulation model (fvGCM), coupled to a mixed layer ocean. We find evidence in support of the "elevated heat pump" (EHP) mechanism that underlines the responses of the atmospheric water cycle to dust forcing as follow. During the boreal summer, as a result of large-scale atmospheric feed back triggered by absorbing dust aerosols, rainfall and cloudiness are enhanced over the West Africa/Easter Atlantic ITCZ, and suppressed over the West Atlantic and Caribbean. region. Shortwave radiation absorption by dust warms the atmosphere and cools the surface, while long wave has the opposite response. The elevated dust layer warms the air over Nest Africa and the eastern Atlantic. The condensation heating associated with the induced deep convection drives and maintains an anomalous large-scale east-west overturning circulation with rising motion over West Africa/eastern Atlantic, and sinking motion over the Caribbean region. The response also includes a strengthening of the West African monsoon, manifested in northward shift of the West Africa precipitation over land, increased low-level westerlies flow over West Africa at the southern edge of the dust layer, and a near surface energy fluxes, resulting in cooling of the Nest African land and the eastern Atlantic, and a warming in the West Atlantic and Caribbean. The EHP effect is most effective for moderate to highly absorbing dusts, and becomes minimized for reflecting dust with single scattering albedo at 0.95 or higher.
Document ID
20110006356
Acquisition Source
Goddard Space Flight Center
Document Type
Conference Paper
Authors
Lau, K. M. (NASA Goddard Space Flight Center Greenbelt, MD, United States)
Kim, Kyu-Myong (Maryland Univ. Baltimore County Baltimore, MD, United States)
Sud, Yogesh C. (George Mason Univ. Fairfax, VA, United States)
Walker, Gregory L. (Lockheed Martin Corp. Laurel, MD, United States)
Date Acquired
August 25, 2013
Publication Date
October 13, 2010
Subject Category
Meteorology And Climatology
Meeting Information
Meeting: 2010 American Geophysical Union Fall Meeting
Location: San Francisco, CA
Country: United States
Start Date: December 13, 2010
End Date: December 17, 2010
Sponsors: American Geophysical Union
Funding Number(s)
CONTRACT_GRANT: NAG5-494000
Distribution Limits
Public
Copyright
Public Use Permitted.

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