HR: 1340h
AN: A53A-0860    [Abstracts]
TI: Modeling and Evaluating the Impact of Deforestation on Precipitation over Central America
AU: * Oglesby, R J
EM: robert.j.oglesby@nasa.gov
AF: NASA/MSFC, 320 Sparkman Dr., Huntsville, AL 35805 United States
AU: Erickson, D J
EM: ericksondj@ornl.gov
AF: ORNL/CSM, PO Box 2008, MS-6367, Oak Ridge, TN 37831 United States
AU: Hernandez, J
EM: hernandezfj@ornl.gov
AF: ORNL/CSM, PO Box 2008, MS-6367, Oak Ridge, TN 37831 United States
AU: Irwin, D
EM: dan.irwin@nasa.gov
AF: NASA/MSFC, 320 Sparkman Dr., Huntsville, AL 35805 United States
AB: Deforestation in the countries comprising Central America can have a profound effect on climate, especially precipitation. Deforestation can induce these important local and regional effects through changes in the surface albedo and the evapotranspiration of water back into the atmosphere. In particular, the increased surface albedo and decline in evapotranspiration that follow the removal of forests both act to reduce precipitation, especially convective thunderstorms, by stabilizing the atmosphere and by reducing the amount of water available to contribute to rainfall. Surface roughness changes are also thought to be important in changing moisture transport. Deforestation can also act to modify or change the way in which Central America is influenced by interannual climate variability, especially the changes due to ENSO. Because of the importance of small-scale orography and land use issues, large-scale models and reanalyses by themselves are insufficient to fully understand and model precipitation variability over C.A. Regional modeling capabilities are critical as a means to examine how large-scale forcing gets downscaled by orographic effects, and to explore the impact of land surface state. We have made runs with the regional climate version of MM5 with the OSU (NOAH) land surface scheme, and with a simpler bucket hydrology scheme. When forests are replaced with grassland (pastureland), temperatures warm over almost all of Central America (and southwest Mexico) by up to 6 deg. C. Precipitation also shows a sharp decrease across much of the region. Changes are largest where the land mass is largest (i.e., smallest changes are found over the narrow countries of Panama and Costa Rica). Evaluating these results includes estimating how much deforestation has actually occurred, and at what rate, as well as using all available observational datasets (especially TRMM) to evaluate model capabilities at simulating precipitation variability over Central America.
DE: 3322 Land/atmosphere interactions
DE: 3309 Climatology (1620)
DE: 1812 Drought
DE: 1833 Hydroclimatology
SC: Atmospheric Sciences [A]
MN: 2004 AGU Fall Meeting