渤海西部雷雨大风统计特征及对流参数指标分析

Statistical Characteristics and Convection Indexes of Thunderstorm and Gale over Western Bohai Sea

使用2011—2016年5—9月渤海西部7个海岛、平台、浮标站加密资料等,对渤海西部雷雨大风统计特征进行分析,结果表明:渤海西部雷雨大风以8~9级为主,主要发生在渤海西部偏南海区;6月发生最多,其次是7月,5月最少,其中,6月过程主要发生在19—23时,同时,高空冷涡影响过程是低槽影响过程次数的两倍,且以带状回波影响最多,占68.8%;大风发生前6~12 h,渤海西部比上游陆地站温度每经度低6℃,而在大风发生前1~2 h,比上游沿岸温度每经度高4℃以上,气压每经度低2 hPa;同时,使用订正探空资料分析渤海西部雷雨大风发生前对流参数指标及其参考阈值,结果表明:抬升指数、大风指数、最佳对流有效位能和0~3 km垂直风切变在渤海西部相对华北陆地更明显,分别给出渤海西部6—9月逐月以及高空冷涡和高空低槽背景下的抬升指数、大风指数、最佳对流有效位能和0~3 km垂直风切变参考阈值,为渤海西部雷雨大风预报提供参考。

The statistical characteristics of thunderstorm and gale over western Bohai Sea were analyzed using dense observation data of seven stations at islands,platforms and buoy stations in western Bohai Sea from May to September during 2011-2016.The results showed that the thunderstorm and gale forces in western Bohai Sea are mainly the maganitude of 8-9,which are seen in the more southern part of the western Bohai Sea,mostly in June,then in July and rarely in May.The process in June,mostly occuring from 19:00 BT to 23:00 BT,is related to cold vortex twice as many as high-level trough,and the most is related to band echo,which accounts for 68.8%.The sea surface temperature is 6℃per longitude lower than the coastal temperature in 6-12 h before the occurrence of thunderstorm and gale,but the sea surface temperature and pressure are higher 4℃per longitude and lower 2 hPa per longitude than in coastal area in 1-2 h before thunderstorm and gale.At the same time,the index thresholds of thunderstorm and gale were analyzed using corrected sounding datas.The results showed that BCAPE,LI,WINDEX and the 0-3 km vertical wind shear are more ob-vious in western Bohai Sea than in North China.The convection index thresholds of BCAPE,LI,WINDEX and 0-3 km vertical wind shear which could offer references for the forecast of thunderstorm and gale in western Bohai Sea from June to September are given,under background of high-level trough and cold vortex.