两次台风外围强对流大风天气对比分析

【目的】为提高台风外围强对流大风预报预警能力。【方法】利用常规气象观测资料和ERA5再分析资料等对2个差异较大的台风在广西造成台风外围强对流大风天气的环流背景、环境条件和雷达回波特征等进行对比分析。【结果】前者的主要影响系统是副高南侧边缘和台风西北侧偏东气流中的东风波动，后者的主要影响系统是台风倒槽，受台风外围环流影响，近地面层风的辐合有利于对流触发。较好的水汽条件和不稳定层结为其发生发展提供了良好的环境条件，2次过程的触发机制略有不同，辐合线位置的差异导致对流初生位置的不同，影响广西的范围也不同。【结论】CAPE值和DCAPE(600 hPa)值等的差异预示着前者对流发展潜势强于后者，所伴随的天气现象也有所不同。雷达回波上的弓形回波和后侧入流急流带来大风天气，大风出现前回波顶高度和最大反射率因子高度不断下降，对大风的出现具有较好的指示意义，单体移速的不同导致大风出现的强度也不同。

Comparative Analysis of Two Severe Convective Gale Weather in Typhoon Periphery

To improve the forecasting and warning capability of severe convective gale associated with typhoon, this paper uses the conventional meteorological observation data and ERA5 reanalysis data in comparing and analyzing the circulation background, environmental conditions and radar echo characteristics of two typhoons with great differences in causing the typhoon-periphery severe convective gale weather in Guangxi on July 31, 2016 and July 31, 2020. The results show that: (1) The main impact system of the former was the easterly wind fluctuation on the south side of the subtropical high and the northwest side of the typhoon, while the main impact system of the latter was the inverted trough of the typhoon. Under the influence of the peripheral circulation of the typhoon, the convergence of near-surface winds was conducive to the initiation of convection. (2) Favorable moisture conditions and unstable vertical structure provided good ambient conditions for the occurrence and development of the severe weather. The triggering mechanisms of the two events were slightly different, and the difference in the position of the convergence line led to different initial convective locations and different impact ranges in Guangxi. (3) The differences in CAPE values and DCAPE (600 hPa) values indicated that the convective development potential of the former was stronger than that of the latter, and the associated weather phenomena were also different. (4) Bow echoes of radar echoes and rear inflow jet streams brought about strong wind weather. The decreasing height of echo top and maximum reflectivity factor before the occurrence of strong winds indicated the presence of gales. The different moving speeds of storm cells also resulted in different forces of strong winds.