青藏高原地区不同下垫面陆面过程的数值模拟研究

Numerical Simulation of Land Surface Process at Different Underlying Surfaces in Tibetan Plateau

利用陆面过程模式Common Land Model(CoLM),选取青藏高原上3个不同下垫面观测站(藏东南站、纳木错站和珠峰站)的观测资料,对这3个野外观测站进行了单点数值模拟试验。根据3个测站的试验数据,对模式中土壤孔隙度和饱和导水率进行了优化,针对青藏高原地区土壤层薄的特点,对模式中土壤分层方案进行了调整。结果表明,调整分层方案后的CoLM模式对3个测站土壤湿度的模拟性能较原分层方案有明显提高,平均偏差均减小0.014以上。但是与观测值相比,藏东南站土壤湿度的模拟整体偏低,纳木错站和珠峰站则整体偏高。对土壤温度而言,3个测站模拟与观测的相关系数都达到了0.9以上,珠峰站偏差较大,调整分层方案后模拟的偏差有一定的改进。模式较好地模拟了3个测站的净辐射、感热通量和潜热通量的日变化和季节变化情况,调整分层方案后潜热通量的改进最为明显。

The simulations of typical land surface processes at three stations in the Tibetan Plateau are evaluated using Common Land Model （CoLM）. The three observation stations are affiliated to the Institu- te of Tibetan Plateau Research, Chinese Academy of Sciences： Southeast Tibet station, Namco station and Qomolangma station. The offline validation experiments were conducted with the observation data from 2007 to 2008. Default soil porosity and hydraulic conductivity of saturated soil in CoLM are adjusted ac- cording to the analyzed soil samples from Southeast Tibet station and Namco station. Vertical soil layering scheme in CoLM is also adjusted to a shallower height according to the soil samples. The results indicate that after the adjustment of soil layer scheme in CoLM, the model can simulate the soil moisture distribu- tion at three stations more reasonably. The average deviation of the simulated soil moisture decrease 0. 014 or even more. However, there are still biases comparing with the observation： The simulated soil moisture is less than the observed at Southeast Tibet station, but more at Namco and Qomolangma stations. As to simulations of soil temperature, net surface radiation, surface sensible and latent heat flux, the bias is re- duced after the adjustment of soil layer scheme, especially the simulation of surface latent heat flux.