青藏高原不同地区夏季近地层能量输送与微气象特征比较分析

Characteristics of Energy Transfer and Micrometeorology in Surface Layer in Different Areas of Tibetan Plateau in Summer

利用2009年7月在青藏高原理塘、林芝、海北、拉萨获得的气象观测资料,对比分析了这些地区近地层气象要素、辐射收支及湍流通量日变化特征。结果表明:无论是高原东部、中部还是北部,无论是高原台地还是高山峡谷区,7月份近地层各气象要素、湍流通量、辐射收支都有明显的日变化。各地区的地表辐射、感热、潜热等最高值都出现在中午,最低值出现在早晨。地表反照率日变化均呈早晚高中午低的"U"型分布。地面热源强度在白天均为热源,正午为强热源,在夜间表现为弱的冷、热源交替出现。7月份近地层地气热量交换中,感热输送作用小,潜热输送占主导地位。动量通量和摩擦速度均在风速较大的下午较大,风速小的早晨小。

Based on the meteorological data acquired in Litang,Linzhi,Haibei and Lhasa in July 2009,the characteristics of the micrometeorology elements and radiation budgets and turbulent fluxes in different areas of the Tibetan Plateau are analyzed.Results show that： the averaged diurnal cycle of meteorology elements,radiation and turbulent fluxes in the surface layer in July are obvious,on the platform and in the canyon,in the central,eastern and northern parts of the Tibetan Plateau.The maximum and minimum values of averaged variations of radiation,latent heat flux,sensible heat flux etc.were observed in the afternoon and at sunrise respectively in all the areas.The surface albedo showed the variations of the ＂U＂ type in daytime.Intensity of surface heat was analyzed to be a heat source in daytime,while it＇s analyzed to be both a weak heat source and heat sink at night in all of the areas.The latent heat transfer played a dominant role in the heat transfer between the atmosphere and the land surface in July,while the sensible heat transfer was small.The values of momentum flux and friction velocity were higher in the windy afternoon than in the calm morning.