MULTI-YEAR ASSESSMENT OF SOIL VEGETATION ATMOSPHERE TRANSFER (SVAT) MODELING UNCERTAINTIES OVER A MEDITERRANEAN AGRICULTURAL SITE

International audienceMediterranean regions will be particularly sensitive to the impact of climate and land-use changes on water resources and vegetation productivity. These changes will affect the functioning and the dynamic of vegetation as well as the regional water and energy balances, with possible feedbacks on the regional climate. In order to analyze and predict the impact of climate and land-use changes on vegetation productivity and water balance as well as their interactions at the regional scale, a critical step is to quantify the uncertainties associated with land surface models (parametrization, processes) and the data used in these models (atmospheric forcing, vegetation and soil characteristics, crop management practises...). This paper addresses this issue and aims at assessing uncertainties in water (evapotranspiration) and energy flux estimates from Soil Vegetation Atmosphere Transfer (SVAT) models. It focuses on the monitoring of a Mediterranean agricultural site over a large time period (10 years), encompassing several development cycles of distinct crops (wheat, sorghum, maize, peas). The investigated sources of uncertainties include: The uncertainties in capturing spatial and seasonal variability of atmospheric variables (mainly incoming shortwave radiation, precipitation and air specific humidity) are analyzed comparing simulations forced with local meteorological measurements and simulations forced with re-analysis atmospheric dataset (SAFRAN database)