一次热带气旋外围飑线对广州白云机场的影响

Impact of a Squall Line in Outer Periphery of Tropical Cyclone on Guangzhou Baiyun Airport

使用常规探测资料、NCEP再分析资料和多普勒雷达产品,分析0809号热带气旋北冕8月4日在登陆前对华南天气的影响。结果表明,在热带气旋北侧外围的偏东风低空急流给广东沿海地区输送充足的水汽以及日升温和副热带高压下沉运动的共同作用,积累了不稳定能量,飑线天气在由弱冷空气造成的边界层辐合线的作用下得以爆发。弓形回波后弱反射率因子通道的出现,说明发展到最强盛阶段的飑线影响白云机场。阵风锋和下击暴流伴随着飑线影响白云机场,产生了强雷暴,近地面层风速迅速加大、风向突然改变以及强降水造成的地面能见度的骤降等,严重影响飞行安全的天气。综合分析风切变等雷达产品判断阵风锋和下击暴流产生的影响飞行安全的低空风切变,飞机飞行时应特别关注飑线低层下击暴流产生的辐散型风切变。

Based on NCEP reanalyzed data and Doppler radar products, a squall line process in outer periphery of tropical cyclone ＂KAMMURI＂ on August 4, 2008 was analyzed. It showed that the establishment of the low-level jet and temperature rising caused by sinking and downdraft within sub-tropical high created the sufficient water vapor and unstable condition in South China. The squall line weather burst out under the action of the boundary convergence line which was caused by weak cold air. The appearance of the weak echo channel behind the arc echo showed that the squall line attacking the airport was in the most powerful stage. Thunderstorm, gust front and downburst were together with the sudden change of the wind direction and the sudden decrease of the ground visibility. Vertical section and wind shear radar products were used to analyze the low-level wind shear threatening the safety of flights.