An offline study of the impact of lakes on the performance of the ECMWF surface scheme

The lake model FLake was incorporated into the European Centre for Medium-Range Weather Forecasts (ECMWF) land-surface scheme HTESSEL. Results from global offline simulations are presented in order to evaluate the model performance in different climates and assess the impact of lake representation on the surface energy balance. The model was forced by ECMWF reanalysis ERA-Interim (1989―2005) near surface meteorology and surface radiation fluxes for the entire globe. Model validation includes lake surface temperatures and lake ice duration. The impact of the snow insulation on lake ice cover duration is discussed, as well as the sensitivity of results to the lake depth. Results show changes in the variation of surface energy storage, and changes in the partition of surface energy fluxes in high latitude and equatorial regions, respectively. General aspects concerning the incorporation of lake models into General Circulation Models for weather forecast and climate modelling are discussed.