Water interception by canopies for remote sensing based evapotranspiration models

Evaporation of intercepted water by canopies accounts for a non-negligible portion of total land surface evapotranspiration. While monitoring evapotranspiration from space technology is increasingly demanded, most evapotranspiration retrieval algorithms face the problem of providing accurate estimation of evaporation from canopy interception. Because of the operations constraints or of the uncertain quality of the near-real-time rainfall estimates from satellites, the implementation of a diagnostic method is preferred to a dynamical model based on a differential equation ruling the evolution of the water storage on the canopy. In this contribution, an empirical model detecting and quantifying intercepted water on canopies, based on one meteorological variable, is optimized with forecasts from a general circulation model. This diagnostic model of interception is implemented in an evapotranspiration retrieval algorithm using mostly space measurements and its impact is commented.