A simple water and energy balance model designed for regionalization and remote sensing data utilization

A simple soil-vegetation-atmosphere transfer (SVAT) model designed for scal ing applications and remote sensing utilization will be presented. The stud y is part of the Semi-Arid Land Surface Atmosphere (SALSA) program. The mod el is built with a single-bucket and single-source representation with a bu lk surface of mixed vegetation and soil cover and a single soil reservoir. Classical atmospheric forcing is imposed at a reference level. It uses the concept of infiltration and evaporation capacities to describe water infilt ration or exfiltration from a bucket of depth d(r) corresponding to the ave rage infiltration and evaporation depth. The atmospheric forcing is divided into storm and interstorm periods, and both evaporation and infiltration p henomena are described with the well-known three stages representation: one at potential (energy- or rainfall-limited) rate, one at a rate set by the soil water content and one at a zero rate if the water content reaches one of its range limits, namely saturation or residual values. The analytical s implicity of the model is suitable for the investigation of the spatial var iability of the mass and energy water balance, and its one-layer representa tion allows for the direct use of remote sensing data. The model is satisfa ctorily evaluated using data acquired in the framework of SALSA and a mecha nistic complex SVAT model, Simple Soil-Plant-Atmosphere Transfer (SiSPAT) m odel. (C) 2000 Elsevier Science B.V. All rights reserved.