Hydrology and Earth System Sciences www.hydrol-earth-syst-sci.net 1027-5606 1607-7938 13 7 2009 10.5194/hess-13-1337-2009 http://www.hydrol-earth-syst-sci.net/13/1337/2009/ http://www.hydrol-earth-syst-sci.net/13/1337/2009/hess-13-1337-2009.html http://www.hydrol-earth-syst-sci.net/13/1337/2009/hess-13-1337-2009.pdf 1337 1347 2009-07-29 Evaluation of the Surface Energy Balance System (SEBS) applied to ASTER imagery with flux-measurements at the SPARC 2004 site (Barrax, Spain) J. van der Kwast hans.vanderkwast@vito.be W. Timmermans A. Gieske Z. Su A. Olioso L. Jia J. Elbers D. Karssenberg S. de Jong Department of Physical Geography, Faculty of Geosciences, Utrecht University, Utrecht, The Netherlands International Inst. for Geo-Information Science and Earth Observation (ITC), Enschede, The Netherlands Institut national de la recherche agronomique (INRA), Avignon, France Alterra, Wageningen University and Research Centre, Wageningen, The Netherlands now at: Flemish Institute for Technological Research (VITO), Mol, Belgium Accurate quantification of the amount and spatial variation of evapotranspiration is important in a wide range of disciplines. Remote sensing based surface energy balance models have been developed to estimate turbulent surface energy fluxes at different scales. The objective of this study is to evaluate the Surface Energy Balance System (SEBS) model on a landscape scale, using tower-based flux measurements at different land cover units during an overpass of the ASTER sensor over the SPARC 2004 experimental site in Barrax (Spain). A sensitivity analysis has been performed in order to investigate to which variable the sensible heat flux is most sensitive. Taking into account their estimation errors, the aerodynamic parameters (<i>h</i>_<i>c</i>, <i>z</i>_<i>0M</i> and <i>d</i>_<i>0</i>) can cause large deviations in the modelling of sensible heat flux. The effect of replacement of empirical derivation of these aerodynamic parameters in the model by field estimates or literature values is investigated by testing two scenarios: the Empirical Scenario in which empirical equations are used to derive aerodynamic parameters and the Field Scenario in which values from field measurements or literature are used to replace the empirical calculations of the Empirical Scenario. In the case of a homogeneous land cover in the footprints of the measurements, the Field Scenario only resulted in a small improvement, compared to the Empirical Scenario. 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