Impact of the Ongoing Amazonian Deforestation on Local Precipitation: A GCM Simulation Study

Impact of the Ongoing Amazonian Deforestation on Local Precipitation: A GCM Simulation Study Numerical simulation experiments were conducted to delineate the influence of in situ deforestation data on episodic rainfall by comparing two ensembles of five 5-day integrations performed with a recent version of the Goddard Laboratory for Atmospheres GCM that has a simple biosphere model (SiB). The first set, called control cases, used the standard SiB vegetation cover (comprising 12 biomes) and assumed a fully forested Amazonia, while the second set, called deforestation cases, distinguished the partially deforested regions of Amazonia as savanna. Except for this difference, all other initial and prescribed boundary conditions were kept identical in both sets of integrations. The differential analyses of these five cases show the following local effects of deforestation.A discernible decrease in evapotranspiration of about 0.80 mm d1 (roughly 18) that is quite robust in the averages for 1-, 2-, and 5-day forecasts.A decrease in precipitation of about 1.18 mm d1 (roughly 8) that begins to emerge even in 12-day averages and exhibits complex evolution that extends downstream with the winds. A larger decrease in precipitation as compared to evapotranspiration produces some drying and warming. The precipitation differences are consistent with the decrease in atmospheric moisture flux convergence and are consistent with earlier simulation studies of local climate change due to large-scale deforestation.A significant decrease in the surface drag force (as a consequence of reduced surface roughness of deforested regions) that, in turn, affects the dynamical structure of moisture convergence and circulation. The surface winds increase significantly during the first day, and thereafter the increase is well maintained even in the 2- and 5-day averages. http://www.deepdyve.com/assets/images/DeepDyve-Logo-lg.png Bulletin of the American Meteorological Society American Meteorological Society

Impact of the Ongoing Amazonian Deforestation on Local Precipitation: A GCM Simulation Study

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Publisher
American Meteorological Society
Copyright
Copyright © American Meteorological Society
ISSN
1520-0477
D.O.I.
10.1175/1520-0477(1995)076<0346:IOTOAD>2.0.CO;2
Publisher site
See Article on Publisher Site

Abstract

Numerical simulation experiments were conducted to delineate the influence of in situ deforestation data on episodic rainfall by comparing two ensembles of five 5-day integrations performed with a recent version of the Goddard Laboratory for Atmospheres GCM that has a simple biosphere model (SiB). The first set, called control cases, used the standard SiB vegetation cover (comprising 12 biomes) and assumed a fully forested Amazonia, while the second set, called deforestation cases, distinguished the partially deforested regions of Amazonia as savanna. Except for this difference, all other initial and prescribed boundary conditions were kept identical in both sets of integrations. The differential analyses of these five cases show the following local effects of deforestation.A discernible decrease in evapotranspiration of about 0.80 mm d1 (roughly 18) that is quite robust in the averages for 1-, 2-, and 5-day forecasts.A decrease in precipitation of about 1.18 mm d1 (roughly 8) that begins to emerge even in 12-day averages and exhibits complex evolution that extends downstream with the winds. A larger decrease in precipitation as compared to evapotranspiration produces some drying and warming. The precipitation differences are consistent with the decrease in atmospheric moisture flux convergence and are consistent with earlier simulation studies of local climate change due to large-scale deforestation.A significant decrease in the surface drag force (as a consequence of reduced surface roughness of deforested regions) that, in turn, affects the dynamical structure of moisture convergence and circulation. The surface winds increase significantly during the first day, and thereafter the increase is well maintained even in the 2- and 5-day averages.

Journal

Bulletin of the American Meteorological SocietyAmerican Meteorological Society

Published: Mar 30, 1995

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