Quoted from: http://www.umr-cnrm.fr/isbadoc/model.html 

      ISBA (Noilhan and Planton, 1989; Noilhan and Mahfouf, 1996) is a soil-vegetation-atmosphere transfer (SVAT) scheme developed at the National Center for Meteorological Research (CNRM) at Météo-France which is used to model the exchange of heat, mass and momentum between the land or water surface and the overlying atmosphere. The model is used in so-called stand-alone mode for development, and in coupled mode in which the model supplies the lower boundary conditions to atmospheric numerical weather prediction models or the upper boundary conditions for distributed hydrological models. ISBA is currently coupled to the Météo-France operational numerical weather prediction model (ARPEGE), the Météo-France climate model or GCM (ARPEGE-climate), the non-hydrostatic mesoscale atmospheric model Meso-NH, and the distributed macroscale hydrologic model MODCOU (see Projects for more details).

      A parameterization of land surface processes to be included in mesoscale and large-scale meteorological models is presented. The number of parameters has been rcduced as much as possible, while attempting to preserve the representation of the physics which controls the energy and water budgets. We distinguish two main classes of parameters. The spatial distribution of primary parameters, i.e., the dominant types of soil and vegetation within each grid cell, can be specified from existing global datasets. The secondary parameters, describing the phyisical properties of each type of soil and vegetation, can be inferred from measurements or derived from numerical experiments. A single surface temperature is used to nt the surface energy balance of the land/cover system. The soil heat flux is linearly interpolated between its value over bare ground and a value of zero for complete shielding of the vegetation. The ground surface moisture equation includes the effect of gravity and the thermo-hydric coefficients of the equations have been either calculated or calibrated using textural dependent formulations. The calibration has been made using the results of a detailed soil model forced by prescribed atmospheric mean conditions. The results show that the coefficients of tlte surface soil moisture equation are greatly dependent upon the textural class of the soil as well as upon its moisture content. The new scheme has been included in a one-dimensional model which allows a complete interaction between the surface and the atmosphere. Several simulations have been performed using data collected during HAPEX-MOBILHY. These first results show the ability of the parameterization to reproduce the components of the surface energy balance over a wide variety of surface conditions.