Sources of Discrepancies between Satellite and Land Surface Model Evaporation Estimates

Monthly-average estimates of evaporation have been derived from a combination of satellite-derived microwave emissivities, day-night differences in land surface temperature (from microwave AMSR-E), downward solar and infrared fluxes from ISCCP cloud analysis, and MODIS visible and near-infrared surface reflectances. The estimates are produced by a neural network. These evaporation estimates have been compared with data from the NOAH land surface model, as produced for GLDAS-2. Areas with persistent, substantial discrepancies between the satellite and model evaporation products have been analyzed. Sources of some discrepancies have been identified, with the aid of in-situ data from flux towers. Examples will be shown where the discrepancies are primarily related to model internal parameters and where they are related to model atmospheric input data.