华南地区西风带飑线和台风飑线环境场特征统计对比分析

利用2012—2015年3—9月华南地区的雷暴大风和雷达数据，挑选了华南地区20次典型飑线过程并进行统计分析表明:华南地区的西风带飑线出现于春季和初夏，台风飑线出现于盛夏；3—4月的西风带飑线一般在凌晨开始发展，中午前后趋于减弱，而7—9月的台风飑线一般在中午或下午开始发展，前半夜趋于减弱。挑选了4次西风带飑线过程和4次台风飑线过程，使用2012—2014年的NCEP物理量分析场，在考虑季节变化的基础上分析两类飑线各种物理量的异同点，结果表明:西风带飑线850 hPa与500 hPa的温差较大，台风飑线则是925 hPa与700 hPa的温差较大；西风带飑线低层暖平流较强但中层不明显，台风飑线相反；在西风带飑线造成的雷暴大风出现前，500 hPa温度平流随时间的变化为显著负值，台风飑线则不明显；西风带飑线的高层辐散和低层辐合较台风飑线更强；台风飑线925 hPa的相对湿度较西风带飑线小，在西风带飑线造成的雷暴大风出现前，500 hPa以干平流为主而925 hPa以湿平流为主，台风飑线则相反。对两种飑线过程进行对比分析表明，雷暴高压的持续加强、扩大及相应冷池的扩大导致西风带飑线的不断加强发展，而台风倒槽的气旋性切变和高低压之间的等压线锋区可能对回波的生成和前期发展有重要作用。 

COMPARATIVE ANALYSIS OF STATISTICAL ENVIRONMENTAL CHARACTERISTICS BETWEEN WESTERLY SQUALL LINE AND TYPHOON SQUALL LINE IN SOUTH CHINA

20 Typical squall line processes are selected based on the March to September's thunder-gust winds and radar data in South China and the temporal distribution are analyzed. The results show that the westerly squall lines appear in spring and early summer, typhoon squall lines appear in summer, and March-April westerly squall lines begin to develop earliest in the morning and tend to weaken around noon while July-September typhoon squall lines begin to develop mostly at noon or afternoon and tend to weaken around early night. Four westerly squall line processes and four typhoon squall line processes are selected and the similarities and differences of various physical quantity characteristics are analyzed between the two types of squall line based on the NCEP data. The results show that the average 850 hPa and 500 hPa temperature difference of the westerly squall line is large, the average 925 hPa and 700 hPa temperature difference of the typhoon squall line is large; the average low-level warm advection of the westerly squall line is strong and the middle-level warm advection is not noticeable, the typhoon squall line is exactly the opposite; the change of 500 hPa average temperature advection over time is a significant negative value before the thunder-gust winds caused by westerly squall lines and the typhoon squall line is inconspicuous; for two types squall lines, 200 hPa is divergent and 925 hPa is convergent, but the westerly squall lines are better defined than the typhoon squall lines; the average 925 hPa relative humidity of typhoon squall line is significantly less than the average season value and less than the 850 hPa relative humidity; there is mainly weak dry advection on 500 hPa and weak dominating advection on 925 hPa before the thunder-gust winds caused by westerly squall lines; there is significant dominatingadvection on 500 hPa and dry advection on 925 hPa before the thunder-gust winds caused by typhoon squall lines. Finally, two squall line processes are compared and analyzed.The results show that the continuous enhancement of thunderstorm high and the expansion of the cold pool lead to the continuous development of the westerly squall line, and the cyclonic shear and isobaric line front may be an important role in the generation and early development of echo.