Observation Studies of Atmosphere Boundary Layer Characteristic over Dunhuang Gobi in Early Summer

Using the sonding data of wind, temperature and humidity in Dunhuang meteorological station during the intensive period of Land-atmosphere interaction field experiment over arid region of Northwest China from end of May to early June 2000, the structure characteristics and change laws of the atmosphere boundary layer over arid region of Dunhuang are analyzed. The results show that the mean value of the atmosphere boundary layer thickness is obviously more higher than usually. The biggest depth of the convective boundary layer exceeds 4000 m, the stable boundary layer depth is 1000 m or so. The turning height of wind direction is at about 3000 m high. The wind was blowing easterly in lower layers and west in upper layers. There is some diurnal variation in the turning height, and the diurnal variation of all nine days is mainly identical. The velocity shear is the bigger in boundary layer. In most time the low-level east jet appears, its intensity is close to 20 m·s~(-1) and its height is about 500 m. The humidity inversion is below about 500 m and it appears mainly in the evening.