Estimation of Regional Evapotranspiration through Remote Sensing

Models used for the remote estimation of evapotranspiration are evaluated using aircraft observations over two distinct vegetation regimes in southwestern Australia. Single-source models using an empirically determined excess resistance term performed better than a two-source model, which does not require such a parameterization. The mean absolute difference between measured and estimated values of the sensible heat flux is below 17 W m22 in comparison with approximately 40 W m22 for evapotranspiration. Estimates of evapotranspiration depend on the closure of the surface energy balance and incorporate all residual errors in this closure. All models performed better over the agricultural vegetation than over the native vegetation.