HR: 14:15h
AN: B22C-03    [PDF]
TI: Global Retrieval of Roughness Length from EOS-Terra Satellite Products and Limited Field Study Data
AU: * Schaudt, K J
EM: schaudt@physics.arizona.edu
AF: University of Arizona, Department of Physics 1118 E. 4th St., Tucson, AZ 85721-0081 United States
AU: Dickinson, R E
EM: robert.dickinson@eas.gatech.edu
AF: Georgia Institute of Technology, School of Earth and Atmospheric Science, Atlanta, GA 30332-0340 United States
AB: Global and regional retrievals, which illustrate the seasonality, of roughness length will be presented. Roughness length is a key factor in estimating the sensible and latent heat fluxes in climate models. In the past the lack of observations made it necessary for most climate models to use relatively crude estimates for roughness length. Typically the roughness length was assigned a constant value for each of the land cover classifications. In reality roughness length depends upon the average height, shape, density and Leaf Area Index (LAI) of the vegetation present. The retrievals presented here depend on these four variables, and they represent a significant improvement over past approaches. The parameterization of roughness length in terms of the four variables (average height, shape, density and LAI) is based on the work of Raupach and Lindroth. The roughness length is formulated in such a way that roughness length can be found either by remote sensing or by variables used in climate models with interactive canopies. The EOS-Terra satellite products used are the overstory plant density and LAI for the seven treed IGBP land cover classes (evergreen and deciduous needle-leaf, evergreen and deciduous broad-leaf and mixed forests, savannah and woody savannah). The tree crown shape (the canopy height-to-width ratio) is based on field studies; it depends on the tree's basic shape (conical or elliptical) and on latitude. At present, the height is of all the vegetation is the average height for the various land cover classifications found in numerous field studies. Limitations of the current retrieval and future improvements will be discussed.
DE: 0400 Biogeosciences
DE: 1615 Biogeochemical processes (4805)
DE: 1640 Remote sensing
DE: 1878 Water/energy interactions
SC: Biogeosciences [B]
MN: 2003 Fall Meeting