Assessment of the EUMETSAT LSA-SAF evapotranspiration product for drought monitoring in Europe

tEvapotranspiration is a key parameter for water stress assessment as it is directly related to the moisturestatus of the soil-vegetation system and describes the moisture transfer from the surface to the atmo-sphere. With the launch of the Meteosat Second Generation geostationary satellites and the setup ofthe Satellite Application Facilities, it became possible to operationally produce evapotranspiration datawith high spatial and temporal evolution over the entire continents of Europe and Africa. In the frameof this study we present an evaluation of the potential of the evapotranspiration (ET) product from theEUMETSAT Satellite Application Facility on Land Surface Analysis (LSA-SAF) for drought assessment andmonitoring in Europe.To assess the potential of this product, the LSA-SAF ET was used as input for the ratio of ET to referenceevapotranspiration (ET0), the latter estimated from the ECMWF interim reanalysis. In the analysis twocase studies were considered corresponding to the drought episodes of spring/summer 2007 and 2011.For these case studies, the ratio ET/ET0was compared with meteorological drought indices (SPI, SPEI andSc-PDSI for 2007 and SPI for 2011) as well as with the anomalies of the fraction of absorbed photosyn-thetic active radiation (fAPAR) derived from remote sensing data. The meteorological and remote sensingindicators were taken from the European Drought Observatory (EDO) and the CARPATCLIM climatologicalatlas.Results show the potential of ET/ET0to characterize soil moisture variability, and to give additionalinformation to fAPAR and to precipitation distribution for drought assessment. The main limitations ofthe proposed ratio for drought characterization are discussed, including options to overcome them. Theseoptions include the use of filters to discriminate areas with a low percentage vegetation cover or areasthat are not in their growing period and the use of evapotranspiration without water restriction (ETwwr),obtained as output of the LSA-SAF model instead of ET0. The ET/ETwwrratio was tested by comparingits accumulated values per growing period with the winter wheat yield values per country published byEurostat. The results point to the potential of using the remote sensing based LSA-SAF evapotranspirationand the ET/ETwwrratio for vegetation monitoring at large scale, especially in areas where data is generallylackin