内蒙古草原陆面通量和边界层结构数值模拟

Modeling Study on the Land Surface Fluxes and the Structure of Planetary Boundary Layer(PBL) over Inner Mongolia Grassland

本文用中尺度MMS模式和修正法国陆面过程模式耦合的中尺度模拟系统模拟了内蒙古草原土壤－植被－大气相互作用（IMGRASS）中尺度实验区生长季后期的地面水分能量通量和边界层结构。结果表明，没有降水时的草场白天大部分时刻潜热通量大于感热通量，降水可使潜热通量变大，波纹比变小，草地波纹比正负转变时间为早8点和晚19点。以乌日图为例的内蒙古沙地白天波纹比大于1，正负转变时间是早7点和晚20点。在降水量不大时，土地利用类型比降水对地面通量影响大。边界层温度廓线符合中纬度陆地边界层日夜演变规律，沙地对流边界层形成早于草原，湿度和风廓线与温度廓线的对应关系较好。

In this paper,a modeling study is carried out on the surface fluxes and the structure of theplanetary boundary layer (PBL) over IMGRASS meso-scale experimental area during anaphase of thegrowth season with a coupled MM5 and modified French lanti surface model(NP89)modeling system. Theresults have indicated that:over prairie without precipitation,the latent heat flux is larger than the sensibleheat flux during daytime with a few exceptions that the sensible heat flux is approximate to,or larger thanlatent heat flux. On rainy days,the latent heat flux increases while the Bowen ratio decreases. The upwardsensible heat flux appears at 8: 00,and opposite at 19: 00. Over very sandy surface, the Bowen ration islarger than during daytime. The upward sensible heat flux appears at 7: 00,and opposite at 20: 00. The in-fluence of land use category to the surface fluxes is larger than that of precipitation when the amount ofprecipitation is not very great. The potential temperature profile evolves along with the regulation for thePBL development of the middle latitude area- The profiles of specific humidity and the wind are in good re-lationship with temperature profile.