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Albedo as a modulator of climate response to tropical deforestationAn atmospheric general circulation model with land surface properties represented by the simplified Simple Biosphere model is used to investigate the effects on local climate due to tropical deforestation for the Amazon basin. One control and three anomaly integrations of 4 years' duration are performed. In the anomaly integrations, rain forest in South America is replaced by degraded grassland. The anomaly integrations differ only in the optical properties of the grassland vegetation, with net surface albedos ranging from the same as to 0.09 lighter than that of rain forest. It is found that the change in climate, particularly rainfall, is strongly dependent on the change in surface albedo that accompanies deforestation. Replacement of forest by grass causes a reduction in transpiration and reduces frictional convergence by decreasing surface roughness. However, precipitation averaged over the deforested area is not necessarily reduced. Average precipitation decreases when the increase in albedo is greater than 0.03. If surface albedo is not increased appreciably as a result of deforestation, moisture flux convergence driven by the increase in surface temperature can offset the other effects, and average precipitation increases. As albedo is increased, surface temperature does not change, but surface latent and sensible heat flux decreases due to reduced radiational energy absorbed at the surface, resulting in a reduction in convection and precipitation. A change in the distribution of precipitation due to deforestation that appears to be independent of the albedo is observed.
Document ID
19950034655
Acquisition Source
Legacy CDMS
Document Type
Reprint (Version printed in journal)
External Source(s)
Authors
Dirmeyer, Paul A.
(Center for Ocean-Land-Atmosphere Studies, Calverton, MD United States)
Shukla, J.
(Center for Ocean-Land-Atmosphere Studies, Calverton, MD United States)
Date Acquired
August 16, 2013
Publication Date
October 20, 1994
Publication Information
Publication: Journal of Geophysical Research
Volume: 99
Issue: D10
ISSN: 0148-0227
Subject Category
Geophysics
Accession Number
95A66254
Funding Number(s)
CONTRACT_GRANT: NSF ATM-90-19296
CONTRACT_GRANT: NAGW-2661
CONTRACT_GRANT: NAGW-1269
Distribution Limits
Public
Copyright
Other

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