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本文中使用的是由西南技术物理研究所研制的FC-Ⅲ型激光测风雷达[21],是一部定位于低空风场3维探测和风切变监测预警的设备,于2021-09-09安装在ZWWW机场25#跑道下滑台附近运行使用, 如图 1所示。
图 1 乌鲁木齐地窝堡国际机场地形特点和测风激光雷达位置
Figure 1. Geographical characteristics around Urumqi International Airport and installation location of LiDAR
测风激光雷达主要性能参数如表 1所示。一次混合模式扫描耗时8 min~10 min,内容包括:PPI模式(3°,6°)、机场跑道方位的RHI显示模式、多普勒风廓线模式(Doppler beam swinging,DBS)和下滑道模式(glide path,GP)。该扫描方式全天候不间断运行,输出产品为风廓线(风速风向、垂直气流分布:正值为上升气流,负值为下沉气流);PPI/RHI径向风场分布图,其正径向风速远离雷达,负径向风速朝向雷达;下滑道迎头风,以观察者视角为标准,正值表示逆风,负值表示顺风;下滑道侧风,以观察者视角为标准,正值为右侧风,负值为左侧风。
表 1 FC-Ⅲ型测风激光雷达主要性能参数
Table 1. Main performance parameters of wind LiDAR FC-Ⅲ
item value average power ≤200 W wavelength 1.55 μm azimuth range 0°~360° elevation angle rang 0°~180° elevation resolution ≤0.1° detection range 0.05 km~10 km range resolution ≤30 m time resolution ≤2 s wind velocity/angle accuracy ≤0.50 m·s-1/≤10°
乌鲁木齐机场一次冷锋型低空风切变过程的LiDAR分析
Analysis of LiDAR in a cold front low-level wind shear in Urumqi Airport
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摘要: 为了研究低空风切变风场结构, 针对乌鲁木齐机场2021-11-26发生的风切变不安全事件, 采用FC-Ⅲ型激光测风雷达产品数据, 配合美国国家环境预报中心再分析资料和常规气象观测资料进行分析和验证, 取得了风切变演变过程的数据。结果表明, 该次风切变过程发生在特定的地形风作用下, 冷锋前小尺度冷空气造成显著的风向风速变化, 东南风急流底部与西北风风带形成倾斜向上的垂直切变区, 并引发冷锋型低空风切变; 风切变发生前1 h, 乌鲁木齐机场周边出现了风场转换; 平面位置显示模式比航空器报告提前10 min监测到风切变, 为东南大风风速骤减区, 且风切变区随冷空气渗透西移; 冷空气渗透过程东南大风层变薄西撤; 07#跑道附近, 正侧风迅速减小且进近过程中伴有风向的大角度转变; 冷空气由25#跑道向07#跑道楔形渗透, 渗透过程发生在08:30~10:25期间; 激光雷达捕捉到该次低空小尺度冷空气活动, 分析出冷空气由东北侧进入呈后倾状态的演变过程和结构, 并触发了中度风切变预警。这一结果对提高气象服务保障能力是有帮助的。Abstract: In order to study the characteristics of the structure of wind shear, the low-level wind shear at Urumqi Airport on 2021-11-26 was analyzed by using the FC-Ⅲ wind light detection and ranging(LiDAR) data, the reanalysis data of National Centers for Environmental Prediction, and conventional meteorological observation data. The evolution of wind shear was calculated. The results show that, the wind shear process occurred under the condition of a specific terrain wind. The small scale of cold air caused the significant changes in wind direction and speed, the bottom of the southeast jet and the northwest wind belt form a vertical shear area inclined upward which led to the cold-front type of low-level wind shear. The wind field around airports had been changed 1 h before the occurrence of wind shear. And the wind shear area was detected 10 min earlier than the report from aircraft which based on the plan position indicator model, the area where wind shear occurred was significant variations in the southeast wind speed, and also followed the movement of cold air to the west. During the movement of cold air, the southeast wind layer became thinner and retreated to the west. Near the glide path 07#. There was not only a sharp reduction of the frontal crosswind, but also a significant change in wind direction. The cold air was wedged from 25# to 07# during 08:30~10:25. The small-scale of cold air activity at low altitude was captured, and a backward of evolution process and structure was figured out, which showed that the pathway entering the airport from northeast, and issued the wind shear warning. The study is helpful to improve the meteorological service support capacity.
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表 1 FC-Ⅲ型测风激光雷达主要性能参数
Table 1. Main performance parameters of wind LiDAR FC-Ⅲ
item value average power ≤200 W wavelength 1.55 μm azimuth range 0°~360° elevation angle rang 0°~180° elevation resolution ≤0.1° detection range 0.05 km~10 km range resolution ≤30 m time resolution ≤2 s wind velocity/angle accuracy ≤0.50 m·s-1/≤10° -
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