Keywords :
Evapotranspiration; Monitoring; Satellite; Soil moisture; Thermal inertia; Validation; Earth observation satellites; Environmental applications; Numerical weather forecasts; Numerical weather prediction models; Operational monitoring system; Satellite application facilities; Medicine (miscellaneous)
Abstract :
[en] Monitoring evapotranspiration (ET) over large areas is required in environmental applications that need frequent information about soil water loss. Such information, if delivered daily, could benefit different sectors relying on drought warning systems. Daily ET estimations can be obtained by the time integration of forecasts by numerical weather prediction models. However, the limited access to observation data and the coarse resolution of the products constrains their use. An operational monitoring system based on Earth observation satellite data and numerical weather forecasts has been set up in the EUMETSAT Satellite Application Facility on Land Surface Analysis: half-hourly and daily ET maps are delivered in near-real time at 3-5. km resolution. Although successful over large parts of Europe and Africa, difficulties of this monitoring system arise in some regions from the strong dependence of the ET model to the numerical weather forecasts used, and especially the modeled soil water status. Therefore, we have developed a new algorithm that assimilates more remote sensing products: the daily vegetation status and the daily soil moisture retrieved from the land surface temperature data of the Meteosat geostationary satellites. The results show a large improvement of the capabilities in ET monitoring in the semiarid regions of Africa.
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