AN INTERCOMPARISON OF SINGLE AND DUAL-SOURCE VEGETATION-ATMOSPHERE TRANSFER MODELS APPLIED TO TRANSPIRATION FROM SAHELIAN SAVANNA

Three models of the partitioning of net radiation into latent and sensible heat fluxes over Sahelian savannah are described. Each model has a different configuration of stomatal and aerodynamic resistances. Their performance was assessed by comparison against field measurements of latent heat flux over savannah vegetation consisting of bushes interspersed with a herbaceous understorey. The modelled results indicate that in dry conditions, a Penman-Monteith based single source model performs adequately when predicting the latent heat flux. However, the models with two sources demonstrate that the bushes and herbs have very different responses to local climate. In all the models, evaporation is highly sensitive to stomatal resistance, suggesting that a better understanding of stomatal response would improve the accuracy of the models.