| The Tibetan Plateau(TP)has the largest area,largest number,and highest altitude of TP lakes on the earth,which has an important impact on the local TP climate.Strengthening the study of TP lakes is helpful for understanding the climate change in TP regions.Numerical simulation is one of the main methods for the study of lakes on the Tibetan Plateau.However,the applicability of different lake models in the Tibetan Plateau are not quite clear yet.In this paper,the two most widely used one-dimensional lake models,Freshwater Lake Model(FLake)and Community Land Model version 4.5(CLM4.5)are used for research.First of all,in order to prevent the difference in the simulation results of the two models due to the difference in the initial field,the meteorological data observed at the Ngoring Lake Station on the Tibetan Plateau were used to drive the two lake models to segmented simulation the thermal state of the Ngoring Lake.Using MODIS surface temperature data and lake temperature and lake energy data observed at the Ngoring Lake station to compare and evaluate the applicability of the two lake models to typical lakes in the Tibetan Plateau.The results show that both the FLake and CLM models can better simulate the thermal conditions of the lake.The CLM lake model is better than the FLake model for the simulation of the surface temperature of the lake and the temperature inside the lake,which is closer to the observed value.The CLM lake model with better temperature simulation is closer to the observed values for the net radiation simulation.The CLM model also simulates lake accumulated energy better than FLake.The reason for the poor simulation of the FLake lake temperature is related to the friction velocity used to calculate the latent heat of sensible heat.The average friction velocity calculated in CLM and FLake modes is different.The average value of the observed friction velocity is 0.22 m·s-1.The average value of the friction velocity in the CLM mode is basically consistent with the observation,it is about 1.5 times the friction velocity in FLake model.After replacing the friction velocity in the CLM into FLake,the recalculated latent heat of sensation has increased,the accuracy of the net radiation simulation has improved,the accumulated energy flux has decreased and is closer to the observed value.the recalculated latent heat of sensation has increased,the accuracy of the net radiation simulation has improved,the accumulated energy flux has decreased and is closer to the observed value.Due to that how well the FLake model simulates lake temperature is related to the calculation of friction velocity in sensible and latent heat.Based on the coupled lake model in CLM4.5 which is closer to the simulation of the lake temperature and observed values,the friction velocity parameterization scheme in CLM4.5 is introduced into the FLake model to improve its friction velocity parameterization scheme.The CLM4.5lake model,the original FLake,and the improved FLake model were used to perform long-term simulations of the thermal status of the Ngoring Lake.The observational data was used to evaluate the improved FLake model.The results show that:in the long-term simulation experiment,the CLM model simulates the thermal state of the lake best.The improved scheme FLake can also better simulate the thermal conditions of the lake,especially the improved scheme FLake can better simulate the lake surface temperature,the temperature of different depths in the lake and the net radiation than the original FLake in the ice-free cooling stage after the lake temperature reaches the annual maximum temperature.The sensible and latent heat simulation increased,and the simulation results in the cooling stage improved more significantly than the heating stage.By studying the applicability of different lake models in the Tibetan Plateau and improving the lake models,it will help to improve the simulation level of lake models in the Tibetan Plateau,and provide reference for further research on TP lakes. |
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