Evapotranspiration monitoring in a vineyard using satellite-based thermal remote sensing

摘要

A two-source energy balance model that separates surface fluxes of the soil and canopy was applied to a drip-irrigated vineyard in central Spain, using a series of nine Landsat-5 images acquired during the summer of 2007. The model partitions the available energy, using surface radiometric temperatures to constrain the sensible heat flux, and computing ET as a residual of the energy balance. Flux estimations from the model are compared with half-hourly and daily values obtained by an eddy covariance flux tower installed on the site during the experiment. The performance of the two-source model to estimate ET under the low vegetation cover and semiarid conditions of the experiment, with RMSD between observed and model data equal to 49 W m~(-2) for half-hourly estimations and RMSD=0.5 mm day~(-1) at daily scale, is regarded as acceptable for irrigation management purposes. Model results in the separation of the beneficial (transpiration) and non-beneficial (evaporation from the soil) fractions, which is key information for the quest to improve water productivity, are also reported. However, the lack of measures of these components makes it difficult to draw conclusions about the final use of the water.