Radiative Bowen ratio to estimate daily fluxes fro msatellite images

摘要

Infrared measurements of canopy temperatures have been extensively used to estiamte daily evapotranspiratio nat regional scale. The aerodynamic and the radiative Bowen ratio formulations give instantaneous evapotranspiration estiamtes for the daytime period, which can be integrated to obtain a value for daily latent heat flux when daytime detailed surface information is available. This paper proposes a different method for estiamting daily evapotranspiration over short well-watered crops with complete canopy from satellite images. The method is based o nthe radiative Bowen ratio-energy balance method and similarity between the diurnal course of latent heat flux and solar radiation. Thsi regression-based approach requires continuous measurement of air vapour pressure, air temperature, surface radiative temperature and solar radiation during daytime. Daily evapotranspiration is estimated with an error under 15