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机场跑道旁的自动气象观测0.5min或1.0min时间间隔气象要素、3-D激光测风雷达资料、边界层风廓线雷达资料以及西宁C波段多普勒天气雷达资料。机场位于西宁天气雷达东偏南方向,距离24km左右,其它仪器分布如图 1所示。
本文中3-D激光测风雷达由成都西南技术物理研究所研制,采用脉冲激光相干探测体制及全光纤相干光路结构[19],以稳频脉冲激光作为照射光源,以大气中直径为0.1μm~100μm大小的气溶胶粒子作为探测目标,通过接收大气中随风飘移气溶胶颗粒的散射回波信号并与雷达本振光进行相干混频获取多普勒频移,并通过对中频信号的数字鉴频技术来获得激光束视线方向的径向风矢量[20]。该雷达具有灵敏度高、工作模式多样、可靠性高、功耗低、体积小、移动方便等特点,其发射激光波长为1.55μm,整机平均电功率约200W,最大探测距离可达10km,风速可测范围为-60m·s-1~60m·s-1,空间和时间分辨率分别为30m和2s。工作模式具有多普勒光束摆动(Doppler beam swinging, DBS)、平面位置指示(plane position indicator, PPI)、量程高度指示(range height indicator, RHI)及下滑道(glide path, GP)等多种复合扫描方式。原始数据包括径向风速、频谱数据、回波信噪比、回波谱强度等; 产品数据包含风廓线(风速风向、垂直气流); PPI/RHI/CAPPI径向风场分布图、跑道纵风和侧风及切变等。其中CA(constant altitude)表示等高。雷达主要性能参量如表 1所示。
Table 1. Main technical parameters of 3-D 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 30m/50m/75m/100m scanning mode DBS/PPI/RHI/GP time resolution ≤2s elevation resolution ≤0.1° wind speed range -60m·s-1~+60m·s-1 wind velocity accuracy ≤0.5m·s-1 wind angle accuracy(profile mode) ≤10°
激光测风雷达研究微下击暴流引发的低空风切变
A study on low-level wind shear caused by microburst using lidar and other data
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摘要: 较强的低空风切变会引发超低空复飞,对飞机安全威胁较大。为了提高飞行安全保障能力,利用激光测风雷达和风廓线雷达提供的资料,对2018-04-26西宁机场突发的一次风切变进行了细致结构分析和形成机理研究。结果表明, 微下击暴流是造成此次低空风切变的主要原因,雷暴高压向外辐散气流和环境风同向叠加是低空风切变形成的直接原因; 干冷空气在2.0km高度处加速下沉,到达近地面形成雷暴高压,随后外流形成水平尺度约3.0km的辐散气流,而触发低空风切变; 此次低空风切变影响时间约8min,对飞行安全威胁最大是下击暴流产生初期; 0.4km~2.0km高度处上升气流迅速转为下沉气流的时刻,较低空风切变发生有约4min的提前量。该研究对如何利用测风雷达进一步提高飞行安全保障能力是有意义的。Abstract: A strong low-level wind shear can cause a super low-level go around, which is a great threat to aircraft safety. In order to improve the ability of safeguard flight safety, the detailed structure and genesis mechanism of the wind shear event were studied using lidar, wind profile radar and other data of Xining Airport on 2018-04-26. The results indicate that microburst is the main cause of the low-level wind shear. The direct reason for the formation of low-level wind shear is the thunderstorm high divergent airflow and the ambient wind which is superposed in the same direction. The dry cold air subsided quickly from an altitude of 2.0km to the near ground and formed a thunderstorm high pressure, and then became an outflow that formed a divergent flow at a horizontal scale of about 3.0km, triggering low-level wind shear. This low-level wind shear lasted about 8min, of which poses the greatest threat to flight safety is at the initial generation of downburst. The time for updraft quickly turning to downdraft at 0.4km~2.0km height is about 4min ahead of the occurrence of low-level wind shear. The research is significant to use wind lidar to improve the ability of flight safety support.
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Key words:
- laser technique /
- microburst /
- thunderstorm high /
- low-level wind shear
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Table 1. Main technical parameters of 3-D 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 30m/50m/75m/100m scanning mode DBS/PPI/RHI/GP time resolution ≤2s elevation resolution ≤0.1° wind speed range -60m·s-1~+60m·s-1 wind velocity accuracy ≤0.5m·s-1 wind angle accuracy(profile mode) ≤10° -
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