青藏高原西部地表通量的年、日变化特征

Annual and Diurnal Variations of Surface Fluxes in Western Qinghai-Xizang Plateau

利用青藏高原西部地区改则和狮泉河两个自动观测气象站1998年全年每天24个时次的风速、温度和湿度等梯度观测资料,采用湍流相似理论,计算了改则和狮泉河的动量通量、感热通量以及潜热通量。结果表明:改则和狮泉河两地的地表湍流通量都具有明显的季节变化和日变化,且其季节变化的相同点表现在感热通量均在5月份最大,1月份最小;而潜热通量均在8月份最大。不同点表现在改则的潜热通量在12月份最小,狮泉河1～5月平均潜热通量为负,以凝结为主,改则的月平均蒸发及全年的蒸发总量比狮泉河的要大。而其感热通量比后者的都小。日变化幅度随季节变化明显,表现在夏季地表通量的日变化幅度大,冬季要小得多。

Using the hourly observed data of in wind speed, temperature and moisture at two auto-meteorological stations in Gerze and Shiquanhe of western Qinghai-Xizang Plateau in 1998, and applying the turbulent similarity theory, the momentum, sensible and latent heat fluxes in Gerze and Shiquanhe are evaluated. The results show that the surface turbulent fluxes have characteristics of significant diurnal and annual variations. The monthly sensible fluxes are maxima in May and minima in Juanuary. The latent fluxes in Gerze and Shiquanhe are maxima in August, and that of Gerze is minima in December and that of Shiquanhe is negative during January to May, taking main as the condensation. The monthly and yearly evaporation in Gerze is larger than that in Shiquanhe, but the former sensible flux is smaller than the latter. The variation of diurnal amplitude is obsvious with season, showing that the flux amplitude in summer is larger and smaller in winter.