A COMPARISON OF A HIERARCHY OF MODELS FOR DETERMINING ENERGY-BALANCE COMPONENTS OVER VEGETATION CANOPIES

Several methods for estimating surface energy balance components over a vegetated surface are compared. These include Penman-Monteith, Deard orff, and multilayer canopy (CANWHT) models for evaporation. Measureme nts taken during the 1991 DOE-sponsored Boardman Area Regional Flux Ex periment over a well-irrigated, dosed wheat canopy are used in the com parison. The relative performance of each model is then evaluated It i s found that the Penman-Monteith approach using a simple parameterizat ion for stomatal conductance performs best for evaporation flux. The D eardorff model is found to have the best relative performance for sens ible heat, while the CANWHT model gives the best results for net radia tion and soil heat flux. The Priestley-Taylor model for evaporation an d a resistance-analog equation for sensible heat flux are also tested.