EVAPOTRANSPIRATION MONITORING IN SEMI-ARID AREAS USING MSG/SEVIRI DERIVED DATA: IMPROVEMENTS FROM THE USE OF LEAF AREA INDEX AND LAND SURFACE TEMPERATURE

Water resource is a major concern for sustainable development in many semi-arid areas. Early detection of drought and monitoring water consumption by agriculture are highly important for adaptation in water use regional policy. As a crucial component of the water cycle, land evapotranspiration is a primary source of information for such water resources assessments, and remote sensing from geostationary satellites offers the possibility to monitor it over large areas at relatively high temporal and spatial resolutions. The Satellite Application Facility on Land Surface Analysis (LSA-SAF) of EUMETSAT proposes an operational evapotranspiration product based on radiation components (surface short and longwave incoming radiation and albedo) derived from the SEVIRI instrument of the Meteosat Second Generation (MSG). Previous validation studies had shown its success for temperate and moist regions, while semi-arid and arid areas of Africa had been shown
to be more prone to model errors. In this contribution, we show that the use of the land surface temperature and leaf area index derived from MSG/SEVIRI improves the evapotranspiration monitoring over semi-arid areas of Europe and Africa. The vegetation dynamics and status of the soil water content available for the process are better represented in the model leading to more accurate results. Statistical comparisons between the current operational LSA-SAF evapotranspiration product from EUMETSAT and in-situ measurements are given to demonstrate the benefits from using new input data derived from the satellite. An updated algorithm incorporating those improvements should be integrated soon into the LSA-SAF operational production.