摘要
本文利用舟山地区的雷暴观测资料、闪电定位资料、MICAPS(meteorology information comprehensive analysis process system)常规气象资料等,对舟山绿色石化基地地区2017-2021年雷暴天气时空分布特征及分类特征进行统计分析.结果表明:2017-2021年该地区年均地闪密度约为1.9～2.1次/km2·a;雷暴天气在2019年后逐年增加.月雷暴分布呈双峰型,8月雷暴最多,月均雷暴日为7.2 d.5年内夏季发生雷暴的次数占全年的58%.从热动力学结构特征将该地区的雷暴天气分为5类:准正压类、斜压锋生类、暖平流强迫类、冷平流强迫类和高架雷暴类,依次占比51%、19%、16%、10%和4%;夏季以准正压类占主导,春季多为斜压锋生类.通过对NCEP 1°×1°物理量再分析场对雷暴过程的指示性进行统计分析,结果显示:CAPE、K指数、LI指数、PWAT是判断夏、秋两季出现强对流的敏感性指标,而春季仅有K指数有较好的指示意义;T(850～500 hPa)在23～24℃,是判断是否出现雷暴的有利指标;高低空垂直风切变(春季:14.61 s-1、夏季:6.89 s-1、秋季:8.30 s-1)是指导不同季节是否发生雷暴最有区分度的判据.
Abstract
This study analyzed the temporal and spatial distributions of thunderstorms in Zhoushan green Petrochemical base from 2017-2021,based on the thunderstorm observation data,lightning positioning data and MICAPS(meteo-rology information comprehensive analysis process system)conventional meteorological data in Zhoushan.The results showed that the average annual ightning density in this area is about 1.9-2.1 times(km2·a)-1 during 2017-2021;After the year of 2019,thunderstorm weather had an obvious increasing trend.The monthly variation of thunderstorm shows a double peak structure with the major peak in August.And the average monthly thunderstorm day is 7.2 days.The occurrence frequency of thunderstorm days in summer(June,July,and August)accounts for 58%of the total thunderstorm days.The synoptic situations associated with thunderstorms are divided into five types:quasi-barotropic category,baroclinic frontogenesis category,cold advection forcing category,warm advection forcing category,and el-evated thunderstorm category.They contribute 51%,19%,16%,10%and 4%to the total occurrence,respectively.The quasi-barotropic category and baroclinic frontogenesis category are the dominant type in summer and spring,re-spectively.Further analysis of environmental conditions associated with thunderstorms suggest that CAPE,K index,LI index,and PWAT are sensitive indicators to judge the occurrence of thunderstorms in summer and autumn,while in spring,only K index has a good indication.The temperature difference between 850 hPa and 500 hPa is around 23-24℃,which is a favorable indicator to judge whether thunderstorm occurs.Additionally,the vertical wind shear be-tween 850 hPa and 500 hPa(14.61 s-1 in spring,6.89 s-1 in summer and 8.30 s-1 in autumn)is the best indicator of whether thunderstorms are occurring in different seasons.
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