一个新的湖——气热传输模型及其模拟能力评估

A New Lake Model for Air–Lake Heat Exchange Process and Evaluation of Its Simulation Ability

基于原有模型,采用温度为预报变量,改进了数值计算方法,并为模型中的浅湖部分加入了底部沉积层模块,建立了一个新的湖泊一维涡扩散水热传输模型。利用德国Kossenblatter湖的观测资料(2003年5～10月)对模型进行了验证,并与其他四个湖泊模式的模拟结果进行了对比。进一步应用本模型和洱海水上观测站的资料(2012年1～12月)详细分析了湖泊水热状态的季节变化和日变化。模拟结果表明:模型可以很好地模拟出洱海水温的季节变化以及日变化,湖泊表面温度和剖面温度的模拟值与观测值吻合很好,最大误差均在2°C范围内;湖泊表面通量的模拟效果比温度略差,尤其对感热通量有明显低估,差值约为实测值的33%。这部分偏差可能是由观测误差、缺测数据的填补与订正方法以及模型表面参数化过于简单所共同导致。

On the basis of an original lake model with a one-dimensional eddy diffusion scheme, a new lake model for the heat and mass exchange processes between the atmosphere and water bodies has been developed. Temperature is used as the predicted variable, which improves the new numerical calculation method, and a lake sediment module is added for shallow lakes. The new lake model is verified and compared with other four lake models by using observation data of Lake Kossenblatter in Germany recorded in May-October 2003. We further use this model to simulate the energy exchange process that occurred over Erhai Lake in Yunnan Province, China, in January-December 2012. A comparison of the model results and observed data indicates that the new lake model can effectively simulate the diurnal and seasonal variations of water temperature in Erhai Lake. The agreement between computed and measured temperature profiles is very good, with an error of less than 2℃. Compared with the water temperature simulation, the heat flux simulation results are poor. The model significantly underestimated the sensible heat flux with a maximum difference of 33% of measured value. This result is likely caused by errors in observation, the data packing and correction method, and simplistic surface parameterization.