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本文中使用的激光雷达是一部由西南技术物理研究所研制的FC-Ⅲ型激光测风雷达,采用多普勒脉冲、全光纤和相干体制。如图 1所示,该雷达安装于ZLXN机场跑道南侧,海拔2184m。作为典型高原机场,ZLXN机场建于两个细长峡谷的中间地带,南北两侧均为密集山脉,山脉平均海拔2500m以上,这种地形利于低空风切变发生。
Figure 1. Geographical environment around Xining Caojiabao International Airport and FC-Ⅲ wind lidar installation location
该雷达测量原理是通过接收大气中气溶胶粒子的后向散射回波信号,并根据信号的多普勒频移来反演大气的风向风速。雷达主要性能参量如表 1所示,雷达发射激光波长为1.55μm,俯仰扫描范围为0°~180°,方位扫描范围为0°~360°。雷达采用混合模式扫描,一次混合模式扫描包括:3个仰角层的平面位置显示模式(plan position indicator,PPI)扫描(3°,4°,6°)、2次沿机场跑道方位的距离高度显示模式(range height indicator,RHI)扫描、1次多普勒光束摆动模式(Doppler beam swinging,DBS)扫描和2次下滑道模式(glide path,GP)扫描。一次混合模式扫描耗时12min,该扫描方式全天候不间断运行。雷达探测资料包括:径向速度、水平风向风速、垂直风向风速、谱宽和信噪比等。
Table 1. Main technical parameters of FC-Ⅲ wind lidar
parameters value average power ≤200W wavelength 1.55μm scan range(azimuth/pitch) 0°~360°/0°~90° detection range 0.05km~10km range resolution 100m scanning mode DBS/PPI/RHI/GP time resolution ≤2s elevation resolution ≤0.1° wind speed range -60m/s~+60m/s wind velocity accuracy ≤0.5m/s wind angle accuracy (profile mode) ≤10° measurements radial velocity, wind profile,
vertical air motion, spectrum width,
signal-to-noise ratio, etc.
西宁机场一次低空风切变的结构和特征研究
Study on the structure and characteristic of a low-level wind shear process that happened over Xining Airport
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摘要: 低空风切变是航空安全的重大威胁,为了研究高原机场典型低空风切变精细结构和演变规律,针对西宁机场2020-02-13出现的两类低空风切变过程,利用FC-Ⅲ型激光测风雷达资料,结合地面实况和风廓线雷达资料进行了分析。结果表明,两类风切变成因和演变特征有所差异,顺风切变线呈“锥形”,由机场西侧向东“嵌入”跑道,而逆风辐合线则呈“弓状”,自东向西影响机场,最大风速均超过20m/s;风场垂直结构具有不同特征,超过15m/s风速带向下传播造成顺风切变,逆风切变时风向首先在近地面变化超过160°;两次过程下滑道模式相邻时刻风速差均超过15m/s。高时空分辨率激光测风雷达能较好地探测到风切变的演变过程和精细结构,这对提高航空安全保障具有重要意义。Abstract: Low-level wind shear is a major threat to aviation safety. To study the fine structure and evolution of typical low-level wind shear in plateau airports, for the two types of wind shear caused by different synoptic processes at Xining Airport on 2020-02-13, FC-Ⅲ wind lidar data combined with wind profile radar and other data were anaylized. The results show that the causes and evolution characteristics of the two types of wind shear are different, the tailwind shear line exhibits as a "cone" and affects the runway from west to east, while the moving path of the headwind shear line is opposite, the maximum wind speed exceeds 20m/s. The vertical structure of the wind field has different characteristics, the wind speed of more than 15m/s propagates downwards causing tailwind shear; for the headwind shear, wind direction changes over 160° in the near-surface layer; in the two processes, wind speed difference between adjacent moments in the glide path mode both exceed 15m/s. The formation and development of the two types of low-level wind shear in the plateau winter are rapid. The high-resolution three-dimensional scanning lidar can detect the evolution process and fine structure of the wind shear, which is significant to improving aviation safety.
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Table 1. Main technical parameters of FC-Ⅲ wind lidar
parameters value average power ≤200W wavelength 1.55μm scan range(azimuth/pitch) 0°~360°/0°~90° detection range 0.05km~10km range resolution 100m scanning mode DBS/PPI/RHI/GP time resolution ≤2s elevation resolution ≤0.1° wind speed range -60m/s~+60m/s wind velocity accuracy ≤0.5m/s wind angle accuracy (profile mode) ≤10° measurements radial velocity, wind profile,
vertical air motion, spectrum width,
signal-to-noise ratio, etc. -
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