Energy and water balance at soil-air interface in a Sahelian region

The aim of this work is an improvement of the parameterization of the soil moisture in the scheme of the Land Surface Process Model (LSPM) for applica tions over desert areas. In fact, in very dry conditions, the water vapour flux plays an important role in the evaporation processes and influences th e underground profiles of humidity and temperature. The improved version of soil moisture parameterization in the LSPM scheme has been checked by usin g the data taken from the database of the field experiment HAPEX-Sahel (Hyd rology-Atmosphere Pilot Experiment in the Sahel, 1990-1992). Model simulati ons refer to three different stations located in Niger (Fallow, Millet and Tiger sites) where input data for LSPM and observations were simultaneously available. The results of simulations, taking into account the water vapou r flux in the soil model LSPM, seem to compare better with the observed beh aviour of soil moisture and turbulent heat fluxes than those overlooking th e water vapour flux, confirming the great importance of the water vapour in such dry conditions.