Water and energy budgets simulation over the AMMA-Niger super-site spatially constrained with remote sensing data

Abstract : s u m m a r y The SEtHyS_Savannah model [Saux-Picart et al., submitted for publication. SEtHyS_Savannah: a multiple source land surface model applied to sahelian landscapes. Agricultural and Forest Meteorology] was developed as an extension of the SEtHyS land surface model to simulate the water and energy fluxes over dry savannah landscapes. The vegetation cover is represented by a two layer model and a mulch approach is used for the soil description. The SEtHyS_Savannah model was regionalized over the AMMA-Niger super-site (about 50 km by 40 km), with the help of remote sensing data. The model uses a regular 1km grid and each cell is divided in sub-grid patches in order to represent land cover and soil heteroge-neities (tile approach). The vegetation cover parameters were prescribed according to the land cover map and the seasonal evolution of the Leaf Area Index (LAI), both derived from SPOT-HRV (Satellite Pour l'Observation de la Terre-High Resolution Visible) data imagery. The atmospheric forcing was assumed homogeneous over the area and provided by a meteorological station installed at the Fakara experimental site. The surface water and energy budgets were simulated over a one-year period (2005) at a 5-min time step and validated against MSG-SEVIRI (Meteosat Second Generation-Spinning Enhanced Visible and Infra-red Imager) land surface temperature and ENVISAT-ASAR (ENVIronnement SATellite-Advanced Synthetic Aperture Radar) soil humidity products. The results show realistic surface fluxes and good agreement with the MSG-SEVIRI temperature observations. The soil moisture comparison presents significant correlation but large root mean square errors. These discrepancies are the consequence of both the use of a non-spatialized atmospheric forcing and to residual vegetation effects on the radar signal. Despite these uncertainties, the results increase confidence in the model representation of Sahelian soil-vegetation processes and open new perspectives to quantify the effects of vegetation changes on evapotranspiration and runoff over the region.
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S. Saux-Picart, C. Ottlé, B. Decharme, C. André, M. Zribi, et al.. Water and energy budgets simulation over the AMMA-Niger super-site spatially constrained with remote sensing data. Journal of Hydrology, Elsevier, 2009, 375 (1-2), pp.287-295. ⟨10.1016/j.jhydrol.2008.12.023⟩. ⟨ird-02153378⟩



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