An image-based four-source surface energy balance model to estimate crop evapotranspiration from solar reflectance/thermal emission data (SEB-4S)

Olivier Merlin (1) , Jonas Chirouze (1) , Albert Olioso (2) , Lionel Jarlan (1) , Ghani Chehbouni (1) , Gilles Boulet (1)

1 CESBIO - Centre d'études spatiales de la biosphère
2 EMMAH - Environnement Méditerranéen et Modélisation des Agro-Hydrosystèmes

A remote sensing-based surface energy balance model is developed to explicitly represent the energy fluxes of four surface components of agricultural fields including bare soil, unstressed green vegetation, non-transpiring green vegetation, and standing senescent vegetation. Such a four-source representation (SEB-4S) is achieved by a consistent physical interpretation of the edges and vertices of the polygon (named T − fvg polygon) obtained by plotting surface temperature (T) as a function of fractional green vegetation (fvg) and the polygon (named T − alpha polygon) obtained by plotting T as a function of surface albedo (alpha). To test the performance of SEB-4S, a T − alpha image-based model and a T − fvg image-based model are implemented as benchmarks. The three models are tested over a 16 km by 10 km irrigated area in northwestern Mexico during the 2007-2008 agricultural season. Input data are composed of ASTER (Advanced Spaceborne Thermal Emission and Reflection Radiometer) thermal infrared, Formosat-2 shortwave, and station-based meteorological data. The fluxes simulated by SEB-4S, the T − alpha image-based model, and the T − fvg image-based model are compared on seven ASTER overpass dates with the in situ measurements collected at six locations within the study domain. The evapotranspiration simulated by SEB-4S is significantly more accurate and robust than that predicted by the models based on a single (either T − fvg or T − alpha) polygon. The improvement provided with SEB-4S reaches about 100 W m−2 at low values and about 100 W m−2 at the seasonal peak of evapotranspiration as compared with boththe T − alpha and T − fvg image-based models. SEB-4S can be operationally applied to irrigated agricultural areas using high-resolution solar/thermal remote sensing data, and has potential to further integrate microwave-derived soil moisture as additional constraint on surface soil energy and water fluxes.

Mots clés: Evapotranspiration; Thermal; Reflectance; Temperature; Albedo; Partitioning

Domaines: Hydrologie; Milieux et Changements globaux

Olivier Merlin, Jonas Chirouze, Albert Olioso, Lionel Jarlan, Ghani Chehbouni, et al.. An image-based four-source surface energy balance model to estimate crop evapotranspiration from solar reflectance/thermal emission data (SEB-4S). Agricultural and Forest Meteorology, 2014, 184, pp.188-203. ⟨10.1016/j.agrformet.2013.10.002⟩. ⟨hal-00922053⟩