青藏高原土壤水热过程模拟研究(Ⅱ):土壤温度

模拟青藏高原土壤水分和热量迁移过程的连续变化对于全球变化研究具有非常重要的意义, 其准确模拟是提高陆面过程模拟精度的重要条件. 利用大尺度水文模型对沱沱河站点以1 h为步长, 共399 d的土壤温度模拟结果与观测结果的对比表明, 土壤中共11个不同深度的观测点的模拟温度总体的变化趋势与观测值一致, 可以进行长时间的模拟. 对于地表温度, 模拟的日变化幅度比实测的变化幅度大, 但均值一致, 原因在于模型的土壤参数中没有考虑有机质含量, 在计算能量平衡时需要增加该土壤参数. 对于土壤底部的土壤温度的连续模拟表明, 采用常数的土壤下界算法和倾斜的(damping)土壤下界算法均与观测值的变化具有一定的差别, 而常数的下界算法与观测值更为接近.

Simulative Study of Water-Heat Process in the Tibetan Plateau (II): Soil Temperature

Water-heat process in the Tibetan Plateau is significant to global climate change. Variances of soil moisture and soil temperature are the key factors of simulating water heat process. In this paper, a water and energy balance macroscale hydrological model is used to compare the simulated result with observed data on the step of 1 hour during 399 days in Tuotuohe. The simulated soil temperature was discussed. The simulated soil temperatures in 11 depths (0 m, 0.2 m, 0.4 m, 0.6 m, 0.8 m, 1 m, 1.3 m, 1.6 m, 2 m, 2.3 m and 2.71 m) were tested. The NSE (Nash-Sufciffe Evaluation) at depths of 0 m, 0.2 m, 0.4 m, 0.6 m, 0.8 m, 1 m, 1.3 m and 1.6 m are greater than 0.9, at depth of 2 m is 0.882, at depth of 2.31 m is 0.7299, and at depth of 2.7 m is 0.369, which indicates that the model is stable in yearly scale and can simulate for a long period in the Tibetan Plateau. The NSE at 2.3 m and 2.71 m is not well either by using damping algorithm or by using constant algorithm, which indicates that the model needs to modify in the future, especially, the energy equation at the bottom of soil.