1.National Climate Center of CMA;2.State Key Laboratory of Severe Weather,Chinese Academy of Meteorological Sciences of CMA
利用台风山竹（1822）和利奇马（1909）登陆期间固定式风廓线雷达、WindCubeV2激光雷达和测风塔的梯度观测数据，结合山竹（1822）登陆前后精细化风场模拟资料，分析了登陆台风不同影响象限内，离地300 m高度内的强风参数及其随距离、海拔高度及下垫面的变化特征。结果表明：距离台风中心200 km水平范围内，最大风速所在高度及风切变指数沿台风半径向外增加，且陆地强风切变指数普遍高于0.12，而海洋下垫面拖曳作用弱，风切变较小，仅在岛屿群附近存在超出国标设计阈值的高切变区域；台风移动方向的右前象限内强风切变指数稳定维持在0.17左右，且对海拔高度不敏感，左后象限存在类似于急流的风廓线，而左前象限内强风的垂直变化在空间上具有较强的非线性特征，边界层低层强风结构较复杂；阵风因子和湍流强度随平均风速增大、离地高度升高而减小；过程最大风向变差角沿台风半径向外减小，且在空间上具有显著的非对称性，其中右后象限的风向变差角最大，半小时风向变化超过30°，且大多发生在台风登陆前或登陆时。研究成果可为我国近海及沿海风电场的微尺度风场模拟及台风风险防御提供帮助。
Based on the in-situ gradient observations from the wind profile radars, WindCubeV2 and masts during the landfall of Typhoon Minguk (1822) and Lekima (1909), combined with the simulated winds of typhoon Minguk (1822) with a finest horizontal resolution of 2 km and vertical resolution of 50-model levels, in which the lower levels are densified, the strong wind structure in the lower level (below 300 m height over sea level or terrain) were analyzed. It showed that within the range of 0-200 km from the typhoon center, (1) the maximum wind speed height and the wind shear index increased outward along the radial direction, and the wind shear index on the land underling surface was generally higher than 0.12. Because of the weak drag effect on the ocean underling surface, the wind shear index was usually small with the exception of island areas; (2) the strong wind shear on the right front quadrant of the moving direction of typhoon remained stable at about 0.17, which was not sensitive to distance and altitude. There existed the wind profile similar to the jet stream on the left rear quadrant, and previous study pointed out that the changes of super-gradient/ sub-gradient wind in the vertical direction should be responsible for the jet type profiles (Tan et al., 2013). The vertical variations of the strong winds on the left front quadrant showed nonlinear characteristics, indicating the more complex strong wind structure over this area; (3) the gust factor and turbulence intensity decreased with the mean wind speed and altitude; (4) the maximum wind direction variation during the landfall of typhoon decreased outward along the radial direction, and exhibited statistically significant spatial asymmetry with the largest variation near the right rear quadrant. Over some areas of the right rear quadrant, the wind direction changed more than 30° in half an hour, and most of them occurred before or during the typhoon"s landfall. It was hoped that these information could be helpful for microscale wind simulation as well as the prevention and mitigation of typhoon disasters over offshore wind farms in China.