中文摘要：

利用2013—2014年6—8月黄河源区近地面的观测数据进行CLM4.5单点模拟植被变化对近地面水热交换影响和能量平衡的研究。结果表明：（1）100%植被覆盖与控制试验（植被覆盖度为50%）向上短波的模拟差值为-6.76 W·m^-2,裸地（植被覆盖度为0%）与控制试验的差值为7.76 W·m^-2。（2）植被覆盖度降低对向上长波辐射的模拟影响较大,其中裸地与控制试验的向上长波辐射模拟差值为5.34 W·m^-2,而100%植被覆盖与控制试验的向上长波模拟差值仅为-0.62 W·m^-2。（3）叶面积指数减少会使地表反照率增大,但辐射通量整体变化幅度不大。其中向上短波平均增加1.35 W·m^-2,潜热平均减小8.43 W·m^-2。（4）叶面积指数增加会使向上长、短波减少,同时潜热通量输送增大,且叶面积指数增加后,向上长波辐射、感热的变化范围略大于叶面积指数减少时。（5）净辐射受到云的影响较大,其变化范围为200~461 W·m^-2。6—7月的土壤热通量在2013年不同深度均达到峰值,其中5 cm深处土壤热通量在6—7月的平均值为6.25 W·m^-2,最大值为30.34 W·m^-2。

英文摘要：

The land surface radiation budget and the impacts of vegetation on water and heat exchanges are the keys of land surface process. By using the field observed data at Maduo from 2013 to 2014,the characteristics of surface radiation budget were analyzed under different types of synoptic conditions. The results showthat：（ 1）The different value of upward shortwave radiation is about 7. 76 W ·m^-2,between 100% vegetation covered and the control test. However,the different value of upward longwave radiation is only-0. 62 W·m^-2.（ 2） The difference value of simulated longwave radiation between bare land and controlled test is about 5. 34 W·m^-2. Moreover,the difference value between 100% vegetation covered and the control test is just-0. 62 W· m^-2.（ 3） The decrease of LAI value has an influence on the increasing land surface albedo. Furthermore,the radiation flux and the surface turbulence flux change little. The upward shortwave radiation increases just about 1. 35 W· m^-2. Meanwhile,the latent heat decreases about 8. 43 W· m^-2.（ 4） On the other hand,the increasing LAI have an impact on the decrease of upward shortwave radiation and upward longwave radiation. What＇s more,the variation of radiation flux is larger when LAI increasing than LAI decreasing.（ 5） The radiation flux reveals obvious diurnal variation. The net radiation varies from 200 W·m^-2to 461 W·m^-2under different types of synoptic conditions. The soil heat flux at different depths reaches the peak from June to July in 2013.