“2012·9·27”环渤海强对流天气监测及成因分析

Monitoring and Genetic Analysis for Severe Convective Weather over Bohai Sea at Sept.27th 2012

利用FY-2E卫星云图、天气雷达拼图、中央台强对流逐小时监测、海岛站及数值模式产品等资料,对2012年9月27日12:00—20:00(CST)出现在环渤海强对流天气过程进行分析。结果表明:位于内蒙东部的低涡系统东移南压,进入河北东部低涡有干冷空气侵入,槽前暖湿气流与地面冷锋叠加,8:00 0~6 km垂直风切变>20 m/s,K指数为33℃,SI指数为-3.8℃,14:00 CAPE达1 883 J/kg,导致强对流天气的发生。同步监测显示:12:00 MCS生成于北京至河北北部,云图中尺度象元TBB为-65^-25℃,带状对流云团强弱交替变化为3~6 h,渤海西海岸带强对流最强时段在14:00—17:00,出现2条飑线,回波强度大于50 d Bz,其中影响秦皇岛的飑线1 h温度下降10℃、气压下降2.7 h Pa;19:00 MCS主体入海后断裂,20:00—21:00在莱州湾及大连半岛重新增强。渤海西海岸带以短时大风、冰雹为主,东海岸带为强降水,雷电大于8 h。

Using some data and means,such as infrared cloud image of satellite FY-2E,weather radar puzzles,strong convection of NMC monitoring hourly, meteorological data on the island and numerical model products and other information, etc., the strong convective weather process over Bohai Sea from Apr.27th in 2012,12 to 20 （CST）was analyzed.The results showed that the low vortex system southeast moved in the Eastern Inner Mongolia, then it took in Hebei Province, with dry and cold intrusion, and front pocket of warm air and surface cold front overlay .As to the index changing, the value of vertical wind shear（between 0 km and 6 km）was greater than 20m/s at 8 ： 00 am, the value on K index was 33 ℃ and SI index was -3.8 ℃ ,Cape reaches to 1 883 J/kg at 2：00 pm.these factors resulted to turning out the severe convective weather.At the same time,the monitoring showed the MCS pixels was produced into Beijing and the northern of Hebei at 12：00 am, dynamic feature of it on synchronous satellite cloud image and the value of TBB was -65--25 ℃ ,The strength of convective clouds banded was alternating from 3 hours to 6 hours ,The strongest periods of severe convective weather in the West Coast of Bohai Sea was during 2 ： 00 pm to 17 ：00 pro.When it appeared two squall lines, radar echo intensity was greater than 50 dBz.Between them, the temperature of the squall line which impacted Qinhuangdao dropped 10 ℃in 1 hour, and the pressure dropped 2.7 hPa; The main body of MCS broken after it got into the sea in the 7：130 pm, and it re-strengthened in the Laizhou Bay and Dalian Peninsula from 8 ： 00 pm to 9 ： 00 om.The West Coast of Bohai Sea met temporary strong wind and hail, and the East Coast met heavy precipitation and the thunder over 8 hours.