An Update on Surface Renewal Estimation of Evapotranspiration

The surface renewal (SR) method for estimating sensible heat flux density (H) has been shown to give good estimates of evapotranspiratiou (ET) when used in an energy balance equation with net radiation (Rn) and soil heat flux density (G). Measurements have been recorded over grass, wheat, grapevines, and avocado trees. In all cases, good relationships were observed between H estimated using the SR method and determined with a sonic anemometer. For example, the standard error of the estimate (SEE) comparing SR with sonic values for H was approximately 15-20 W m for measurement heights between 0.3 and 1.0 m height over 0.1 m tall grass. The SR analysis is a highly accurate and inexpensive method for estimating H and ET. Only high frequency temperature data are required to estimate H.