呼伦贝尔沙质草原槽形风蚀坑表面气流特征

根据野外对呼伦贝尔沙质草原槽形风蚀坑表面二次流的观测结果，利用相对风速（v／vR400）比较不同部位之间气流在水平方向上的变异情况。发现：槽形风蚀坑内气流结构紊乱，坑内前部位置出现风速随高度降低的现象，形成反向回流；风蚀坑内在斜向气流的情况下有螺旋环流产生，由于气流聚集，在坑后部形成的高速气流容易将大量沙物质搬运到坑后；在坑口积沙区坡脚遇阻减速后气流辐散溢出。认为槽形风蚀坑是在碟形坑的基础上，沿强风能方向延伸扩展，3个出风口最终合并而形成的大型风蚀地貌形态。

Air flow dynamics of the blowout trough in the Hulun Buir sandy grassland

Blowout trough is the best surface expression of the aeolian processes responding to regional climatic changes and human ctivities,which is also the driving force of grassland landscape heterogeneity.When the wind approaches to the blowout trough parallel to the thread orientation,the velocity is become slow because of the expansion,and until jet usually occur at the 3/4 of the central line of the deflation basin.The results show that more and more air flow was sucked into the blowout trough,and the rim of the blowout trough is usually eroded by this process,and flow deceleration and expansion occur to the depositional lobe.When the wind approaches to the blowout trough obliquely,the air flow is usually extremely turbulent,and air flow was sucked into the blowout trough from the rim,because the erosion wall is very steep,so the air flow is steered as return flow,and erodes the coming wall and deposited on the opposite wall.Blowout trough morphologies are explained as a function of these air flow patterns.