塔克拉玛干沙漠风蚀起沙观测研究——试验介绍与观测结果初报

介绍了中国气象局乌鲁木齐沙漠气象研究所在塔克拉玛干沙漠开展的风蚀起沙观测试验。对观测试验所获观测资料进行了初步分析,获得了一些有关塔克拉玛干沙漠风沙运动的特征。主要结果为,下垫面状况影响风沙流结构,塔中、若羌0~100 cm高程风沙流结构完全符合指数分布,肖塘则上部偏离指数分布;3地0~100 cm高程风沙流分别有72.4％、47.3%、62.6%的输沙量分布在0~30 cm高程内;3地风沙流输沙的粒径以细沙、极细沙、粉沙为主,其中极细沙可占到输沙量的43.8%~75.5%;风沙流中贴地层风速廓线受风沙相互作用的影响,不再符合对数分布,更加符合幂函数u=azb分布,拟合系数均大于0.93;沙尘撞击颗粒数与2 m高度风速变化趋势一致,塔中、肖塘、若羌3地的临界摩擦速度分别为0.25 m·s-1,0.27 m·s-1,0.21 m·s-1。

Observation of Dust Emission by Wind Erosion in Taklimakan Desert:Field experiment and preliminary report

Field observation experiments on dust emission by wind erosion were conducted in Taklimakan Desert. Some analyzing results are obtained. The underlying surface situation directly influences sand flow structure. The sand-transporting volume of sand flow in Tazhong, Xiaotang and Ruoqiang decreases gradually with height. The sand-transporting volume at the height of 0~100 cm in Tazhong and Ruoqiang meets the exponential function completely, but that in Xiaotang deviates from the exponential function partially. 72.4%, 47.3% and 62.6% of sand-transporting volume at 0~100 cm are distributed in 0~30 cm in Tazhong, Xiaotang and Ruoqiang, respectively. The particles in sand flow are mainly fine sand, very fine sand and silt, in which 43.8%~75.5% is very fine sand. Wind speed profiles of near-surface layer follow u=azb distribution, and all the fitting coefficients are larger than 0.93. The change trend of rebounding particles is identical with that of wind speed at height of 2 meters, and the threshold friction velocities in Tazhong, Xiaotang and Ruoqiang are 0.25 m·s-1, 0.27 m·s-1, 0.21 m·s-1, respectively.