A one-dimensional model intercomparison study of thermal regime of a shallow turbid midlatitude lake

Abstract

Abstract. Results of a lake model intercomparison study conducted within the framework of Lake Model Intercomparison Project are presented. The investigated lake was Großer Kossenblatter See (Germany) as a representative of shallow (2 m mean depth) midlatitude turbid lakes. Meteorological measurements, including turbulent fluxes and water temperature, were carried out by the Lindenberg Meteorological Observatory of the German Meteorological Service (Deutscher Wetterdienst, DWD). Eight lake models of different complexity were run, forced by identical meteorological variables and model parameters unified as far as possible given different formulations of processes. All models generally captured diurnal and seasonal variability of lake surface temperature well. However, some models were incapable of realistically reproducing temperature stratification in summer. Total heat turbulent fluxes, computed by surface flux schemes of lake models, deviated on average from those measured by eddy covariance by 17–28 W m−2. To realistically represent lakes in numerical weather prediction and climate models, it is advisable to use depth-resolving turbulence models (or equivalent) in favour of models with a completely mixed temperature profile. While the effect of heat flux to bottom sediments can become significant for bottom temperatures, it has no important influence on the surface temperatures.