LAND-SURFACE ENERGY AND MOISTURE FLARES - COMPARING 3 MODELS

Three different land surface schemes that mt designed for use in atmos pheric general circulation models are compared. They were run in offli ne mode with identical atmospheric forcing values that were observed a t Cabauw. This procedure allows one to analyze differences in the simu lations that are not caused by different atmospheric conditions and to relate them to certain model characteristics. The intercomparison sho ws that the models produced similar results for surface temperature an d total net radiation, which are also in good agreement with the obser vations. But they underestimate latent heat flux and overestimate sens ible heat flux in summer. Differences in the components of energy and hydrological cycle as simulated by the schemes can be related to diffe rences in model structures. The calculation of the surface temperature is of major importance, particularly on a diurnal timescale. Dependin g on the scheme chosen, the simulated surface temperature is closer to the observed radiative surface temperature or the observed soil tempe rature at a depth of a few centimeters. Ii a land surface scheme Is go ing to be coupled to an atmospheric model, this needs to be considered ; The simulation of the surface energy fluxes can be improved by caref ul calibration of the relevant parameters according to the conditions at the observational site. The stomatal resistance was found to be an essential parameter in determining the evolution of evapotranspiration for the Cabauw simulations.