半干旱区沙尘天气近地层湍流通量及起沙研究

 利用2005年春季朱日和气象站20 m气象塔的观测资料，结合同期的PM10质量浓度资料，分析了半干旱地区不同沙尘天气下近地层湍流通量的变化特征以及PM10质量浓度与起沙之间的关系。结果表明,动量通量在15:00左右达到极大值；感热通量在白天为正值，中午12:00左右达到峰值，而晚上变为负值，并在凌晨达到谷值；由于3月份下垫面湿度大，导致潜热通量经常全天为正值，并在16:00左右达到峰值；PM10质量浓度与摩擦速度的二次方呈正比，临界起沙风速和临界摩擦速度分别为7 m·s－1和0.7 m·s－1。

Research of Turbulent Flux and Dust Emission During Sand-dust Events in Surface Boundary Layer over Semiarid Area

The characteristics of meteorological elements of atmospheric surface layer during sand-dust events are studied based on the observational data obtained from 20 m meteorological tower in Zhurihe Meteorological Station of Inner Mongolia in spring of 2005, and in combining with the mass concentration of PM10 data a comprehensive analysis is conducted. We analyze the variation features of turbulent fluxes and the relationship between the mass concentration of PM10 and dust emission during different sand-dust events over atmosphere surface layer. It was found that: (1) The momentum flux reaches the maximum at about 15:00 BST; (2) The value of sensible heat flux is positive during the daytime and reaches the maximum at 12:00 BST, while the value changes to be negative during the nighttime and get the minimum at 24:00 BST; (3) Because the soil moisture is relatively high on March, the value of latent heat flux is positive during the whole daytime and reaches the maximum at 16:00 BST; (4) The mass concentration of PM10 is approximately proportional to the second power of friction velocity, and the threshold values of wind speed and friction velocity are found to be about 7 m·s-1 and 0.7 m·s-1, respectively.