耦合冻土方案的大气模式对祁连山区春季土壤状况的模拟

对黑河流域上游山区水源涵养林区2003年春季土壤温度、湿度变化进行分析,运用耦合冻土参数化和没有耦合冻土参数化的大气模式MM5对该区春季过程进行了模拟,并与观测值进行对比,对模拟的产流量做了初步分析.结果显示:考虑冻土参数化方案对土壤温度模拟的改进主要体现在表层土壤,对深层土壤温度的模拟没有大的改进;考虑冻土参数化方案改进了对100 cm深度以内的土壤含水量的模拟,很大程度上缩小了模拟值与观测值之间的绝对误差.总体来讲,考虑了冻土参数化的模拟结果在一定程度上改进了模式对黑河流域上游季节冻土区土壤温、湿状况的模拟,在一定程度上逼近祁连山区的春季土壤状况.考虑冻土参数化和没有考虑冻土参数化对产流量的模拟表明,冻土参数化对产流量模拟有很大影响,冻土形成的不透水层可以产生更多的地表径流.尽管考虑冻土参数化过程对模拟结果有一定程度的改进,但模拟结果与实测结果还是有一定差距的.因此,进行寒区冻土过程模拟时,还需要进一步对土壤信息、模式物理过程,大气背景场驱动数据以及局地因素进行详细而精确的考虑,以期进一步提高模式在寒区的模拟性能,特别是为高寒山区无观测地带陆气相互作用研究提供依据.

Application of Atmospheric Model Coupled with Frozen Soil Parameterization to Simulating Spring Soil Condition in the Qilian Mountains

The variation of observed soil temperature and soil water content at the Water Resources Conservation Forests in the upper reaches of the Heihe River from 1 January to 10 May 2003 is analyzed.Modeling is made during the same period using the atmospheric model MM5,with and without a frozen soil parameterization scheme.Soil temperature and soil water content simulated by the two experiments are compared with the observed ones.The simulated surface runoff is analyzed also.The following conclusions are obtained: The mesoscale atmospheric model MM5 coupled with the frozen soil scheme could improve the soil temperature simulation at the upper layer in some extent.The soil temperature at the deeper layer does not be affected much.Soil water content within 100 cm depth from the ground surface simulated by MM5 coupled with the frozen soil parameterization scheme is closer to the observed one,with less bias between simulation and observation.In general,soil temperature and water content simulated by atmospheric model coupled with the frozen soil parameterization,in some extent,are closer to the observations at the upper reaches of the Heihe River.Simulation of mesoscale atmospheric model could be improved by coupling the frozen soil scheme.More surface runoff is generated by the MM5 simulation with the frozen soil scheme than that without the scheme.Whereas,there are some gapes between simulation and observation.The possible reasons are analyzed preliminarily.Surface runoff generation simulated by MM5 is affected by the frozen soil scheme.Through the above analysis,one can see that it is necessary to consider the soil information,model physics,initiation and local factors in detail in order to get more precise simulation results and provide a theory base to the study of land atmospheric interaction in cold regions,especially in the zones without equipment observation.