在一维涡扩散模型的基础上,发展了考虑有四季冻融相变过程和因异重层结产生垂向对流混合过程的水体(如湖泊、湿地)与大气之间的水-热传输模型.模型采用焓代替温度作为预报变量,既方便了处理水的冻融相变问题,也提供了有效的计算求解方法.利用以色列Kinneret湖和美国Montana州的Lower Two Medicine湖的观测资料,对模型的性能和引入对流混合合理性进行了验证,说明了本水体-大气热传输模型是能刻画湖泊、湿地等水体与大气间重要的水、热量输运物理过程.通过相同气象条件下不同深度的湖泊和湿地蒸发潜热的对比,得出湿地蒸发大于浅湖和深湖蒸发,这符合实际观测的结果.
Based on a one-dimensional eddy diffusion model,a model to study the water mass and energy exchange between the water body(such as lake and wetland) and the atmosphere is developed,which takes the phase change process due to the seasonal melting and freezing of water and the convection mixing process of energy caused by temperature stratification into consideration. The model uses enthalpy instead of temperature as predictive variable,which will help to deal with the phase change process and to design an efficient numerical scheme for obtaining the solution more easily. The performance of the model and the rationality of taking convection mixing into the consideration are validated by using observed data of Kinneret Lake in Israel and Lower Two Medicine Lake in Montana State in America. The comparison of model results with observed data indicates that the model presented here is capable of describing the physical process of water mass and energy between the water body(lake and wetland) and atmosphere. Comparison of the result from wetland with shallow and deep lakes under the same forcing conditions shows that the evaporation from wetland is much greater than that from lakes,which accords with the real observation fact and physical mechanism.
At present, the Topographic Index Model （TOPMODEL） has been recommended for integration in Land Surface Models （LSMs）. But, the applicable scope of the original TOPMODEL （OTOP） is limited because the OTOP derivation relies on three fundamental but unrealistic assumptions. In this paper, several versions of a generalized TOPMODEL （GTOP）, which relax some unrealistic assumptions involved in OTOP, are presented, and the theoretical derivationsn to obtain these modifications are demonstrated in detail. Specifically, the extension for the OTOP applicability comes down to following three basic cases： （1） Give up the assumption of spatially uniform recharge rate to the groundwater and let the rate be spatially varying, （2） Keep same original exponential distribution profile of hydraulic conductivity used in OTOP but change the saturated hydraulic conductivity and effective soil depth from spatial constants in OTOP to spatially variable quantities; and （3） Extend the original exponential distribution profile of hydraulic conductivity to more general power law distribution profile of hydraulic conductivity together with spatially variable saturated hydraulic conductivity and effective soil depth. Finally, a brief numerical sensitivity study based on one version of GTOP using an exponential distribution profile for soil hydraulic conductivity is conducted. This shows the heterogeneous effects of the effective soil depth, saturated hydraulic conductivity, at ground surface and groundwater recharge rate on hydrological processes and serves as an example application of GTOP to a heterogeneous catchment.
