基于SHAW模型的青藏高原唐古拉地区活动层土壤水热特征模拟

Simulation of the Soil Water-Thermal Features within the Active Layer in Tanggula Region,Tibetan Plateau,by Using SHAW Model

利用唐古拉综合观测场活动层及气象塔2007年的数据资料,结合SHAW模型在3种不同地表反照率选取方案下进行模拟试验,对唐古拉地区活动层土壤水热特征进行了单点数值模拟研究.通过观测值与3种模拟值的对比分析,结果表明:SHAW模型能够较为好地模拟多年冻土区地表能量通量、活动层土壤温度特征,而对土壤含水量模拟不太理想,但对其变化趋势模拟较好;在模拟试验中,模型输入参数地表反照率取1-12月各月平均地表反照率后,模型对地表能量通量、活动层土壤温度和湿度的模拟效果有了明显的提高;而用一种地表反照率参数化方案的计算结果对模型输入参数进行修正后,模型对活动层土壤温度和湿度的模拟效果有了明显的提高,对地表能量通量的模拟效果提高不明显.总体上,SHAW模型对高原多年冻土区土壤冻融过程的模拟具有优势,是研究高海拔多年冻土区活动层土壤水热过程较为理想的陆面模型.

Using the data observed from the meteorology gradient tower and within the active layer at the Tanggula Observation Site on the Tibetan Plateau in 2007,combined with the SHAW model,the soil hydro and thermal features within the active layer were simulated.Meanwhile,three different programs of surface albedo have been tested during the process of simulation.Comparing the observed data with the three simulated values,it is revealed that the SHAW model could successfully simulate the surface energy fluxes and the soil temperature features within the active layer in permafrost regions,while the simulation of soil unfrozen water is not so good,but the simulated changing tendency seems better.In the simulation,it will have obvious improvements in the simulation of the surface energy flux and soil temperature and moisture within the active layer when the monthly average surface albedo of each month in a year is taken as the model input.After revising the model input parameters by using the computing results from a parameterization scheme of the surface albedo,the simulation results of the soil temperature and moisture within the active layer has improved significantly.However,there is not obvious advance in the simulation of the surface energy fluxes.Overall,the SHAW model has advantage in simulating the soil freezing and thawing process in permafrost regions of the Tibetan Plateau.It is an ideal land surface model used to study the hydro and thermal processes within the active layer in the permafrost regions with higher elevations.