青藏公路沿线多年冻土区土壤热通量参数化方案的优化和检验

土壤热通量是地表能量平衡的重要分量，其估算方案在研究地表能量平衡研究中必不可少。利用青藏公路沿线5个站点0~20 cm的实测土壤层温、湿度及5 cm土壤热通量资料，以翁笃鸣气候学计算方案为基础建立了优化的5 cm土壤热通量计算方案。通过唐古拉和西大滩两个独立站点的检验结果表明，优化方案的结果相对于原方案有较大的改善，唐古拉和西大滩5 cm土壤热通量均方根误差值分别减小了3.2 W·m^-2和4.8 W·m^-2，而相对误差分别减小了61.9%和36.1%，即新方案能够较好地估算出青藏公路沿线多年冻土区5 cm土壤热通量。使用优化方案模拟了青藏公路沿线11个站点5 cm土壤热通量变化，结果显示，近十年青藏公路沿线土壤热通量呈现出增大的趋势，其中，5 cm土壤热通量增大了近1.0 W·m^-2，而且各观测场的年平均土壤热通量值均大于0.0 W·m^-2，表明就年尺度而言，热量有盈余，盈余热量用于加热下层土壤，引起活动层厚度增加，平均状况下土壤热通量每增大1.0 W·m^-2，活动层厚度增大约21.0 cm。

Optimization and validation of the soil heat flux parameterization scheme in permafrost regions along the Qinghai-Tibet Highway

Soil heat flux acts as a key role in the surface energy balance, so it is also essential for the calculation and simulation of surface energy balance. Based on the climatology calculation scheme from Weng Duming, a soil heat flux calculation scheme was optimized using soil temperature, moisture and heat flux data along the Qinghai Tibet Highway. Independent data test results showed that compared with original scheme results, the reliability of optimized scheme has been greatly improved. The root mean square error in the Tangula and Xidatan sites had reduced 3.229 W·m^-2 and 4.821 W·m^-2, respectively, and the relative error had reduced 61.9% and 36.1%, respectively, so the new scheme can be used to effectively calculate local soil heat flux at the depth of 5 cm. In addition, the optimized scheme was used to simulate soil heat flux at the depth of 5 cm of 11 sites along the Qinghai Tibet Highway, the results showed that the soil heat flux at this depth presented an increasing trend, with a rate of nearly 1 W·m^-2 during the past decade. Moreover, the annual average soil heat flux values in all sites were not less than 0.0 W·m^-2, which indicated that local heat had a surplus at the yearly scale. The surplus heat could be used to heat the shallow soils, causing active layer thickness to increase significantly; when the soil heat flux increases 1.0 W·m^-2, active layer thickness will increase 21 cm or so.