83rd Annual

Thursday, 13 February 2003: 11:30 AM
Impact of Deforestation on Precipitation
Somnath Baidya Roy, Princeton University, Princeton, NJ; and S. W. Pacala and C. P. Weaver
Wholesale destruction of tropical forests on continental scales has been shown in numerical experiments to produce large changes in regional climate, e.g., a decrease in precipitation. Other work has shown, however, that mesoscale landscape heterogeneity, as created, for example, by partial deforestation, can induce atmospheric circulations that can alter the intensity and spatial distribution of the pre-existing pattern of precipitation, sometimes enhancing total rainfall in a given region. The interaction between large-scale and mesoscale effects and their net impact on total rainfall for a given amount of deforestation remains an open question. Here we use high-resolution numerical experiments with the Regional Atmospheric Modeling System (RAMS) to examine the dependence of monthly-to-seasonally averaged precipitation on two factors: (i) the extent of deforestation; and (ii) the degree of forest fragmentation (patchiness). We discuss the relative roles of these two factors in determining total rainfall.

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