基于相干多普勒测风激光雷达的不同成因类型的低空风切变观测

为实现不同成因类型的低空风切变观测,利用两台相干多普勒测风激光雷达在北京首都国际机场展开试验观测。针对干性雷暴和地形引起的两类风切变,分别采用多普勒波束摆动(Doppler Beam Swing,简称DBS)和下滑道两种扫描模式进行风切变的探测与识别。结果表明,DBS模式风切变识别方法可有效识别干性雷暴引起的水平低空风切变,下滑道模式可有效识别地形诱导的下滑道顺风和逆风风切变。干性雷暴造成的风速骤增、风向突变和上升下降气流的强烈对流是引发低空风切变的主要原因。地形诱导风切变主要由高速气流和复杂下垫面相互作用产生,具有偶发性和瞬变性的特点。

Low-level wind shear observation based on different physical mechanisms by coherent Doppler lidar

In this paper, two coherent Doppler lidars were used to observe the low-level wind shear induced by dry thunder storms and terrain at Beijing Capital International Airport. The experiments respectively adopted Doppler Beam Swing (DBS) and Glide Path wind shear identification method to alert the wind shear of the above two types. The results show that the DBS method and Glide Path mode can respectively identify horizontal wind shear caused by dry thunderstorms and terrain. Dry thunderstorms bring sudden increase of wind velocity, abrupt change of wind direction and strong convection of updrafts and downdrafts, which causes the low-level wind shear. Terrain-induced wind shear with the transient and sporadic nature is mainly produced by the interaction between high-speed airflow and complex underlying surface.