Evaporation from a bare soil evaluated using a soil water transfer model and remotely sensed surface soil moisture data [Using daily radar measurements]

Daily surface soil moisture data, obtained with a C band scatterometer on a bare soil, provide the upper boundary condition for a numerical soil water transfer model. The model uses an implicit finite difference scheme to solve the nonlinear Richards equation. The soil is represented by two layers differing in hydraulic conductivity. Following calibration by comparison of calculated and measured soil moisture profiles, the model provides estimates of the water budget and the boundary fluxes. The estimates of evaporation computed from the model compare favorably to those derived from soil water content measurements by the neutron probe when only the radar data are used to define the surface boundary condition. When known precipitation rates are also used, evaporation is underestimated.