SHAW模式对青藏高原中部季节冻土区土壤温、湿度的模拟

Simulation of Soil Temperature and Moisture in Seasonally Frozen Ground of Central Tibetan Plateau by SHAW Model

利用水热耦合模式(Si multaneous Heat and Water,SHAW)及"全球协调加强观测计划之亚澳季风青藏高原试验(CAMP/Tibet)"中那曲地区BJ站2002年8月1日—2003年8月31日的观测资料,对青藏高原中部季节冻土区的土壤温湿特征进行了单点模拟研究。SHAW模式能较好地模拟BJ站不同深度土壤温度,模拟值与观测值的相关系数在0.97以上,平均偏差在1℃以内。随着土壤深度增加,土壤温度的模拟效果变好,100 cm以下土壤温度的观测值和模拟值基本吻合。由于净辐射和土壤热通量在冬、春季的模拟值较观测值略偏大,使得模拟的土壤温度在冬、春季也略微偏大。就模拟结果而言,60 cm以上土壤温度对降雪是比较敏感的。模拟的土壤湿度基本上能够再现土壤未冻水含量随时间的实际变化趋势,除4 cm土壤层外,其他层的模拟值与观测值差异较大。由于影响土壤湿度的因素较多及其本身具有较复杂的相态变化,陆面模式中对其进行合理的参数化仍是难点之一。

Using the Simultaneous Heat and Water（SHAW） model and the observed data at BJ site from CEOP Asia-Australia Monson Project on the Tibetan Plateau（CAMP,2001-2005） during 1 August 2002-31 August 2003,the soil temperature and moisture characteristics in seasonal frozen soil region of central Tibetan Plateau have been predicted.The simulated lower-layer soil temperature is superior to the upper-layer soil temperature.The simulated soil temperature at 250 cm is quite close to the observed value.The simulated soil temperature is larger than the observed result during winter and spring due to large simulated net radiation and soil heat flux.The simulated soil moisture embody basically temporal change trend of soil liquid water content,but the deviation between the simulated and observed is large.It is difficult for land surface model to simulate reasonably soil moisture due to complexity of water phase transition and multi-control of soil moisture.