南京雷与雨相互关系分析

根据南京气象观测站1951—2007年57 a雷暴日及降雨记录资料,分析了干雷、湿雷和雨中有雷比率的变化特征,得出:57 a来湿雷明显多于干雷,干、湿雷日气候倾向率都为负值,趋势减少,但湿雷减少更为明显;干、湿雷都是夏季最多,冬季最少;南京市从历年某天发生湿雷的概率得:历史上任意一天湿雷发生概率超过0.2的日期都集中在7、8月,其中南京发生湿雷最高概率在7月20日,与本省苏南和苏中各市基本一致,比苏北发生湿雷概率最高日期早5~6 d。南京雨中有雷比率主要分布在0.12~0.25之间,平均为0.19;雨中有雷的比率呈逐年缓慢下降趋势,但近几年出现雷暴的比率略有增多;各月雨中有雷比率呈单峰型,夏季比率较其他季节大。结合1961—2007年梅雨期资料,统计得出历年梅雨期有雷比率分布区间广,为0~0.9,梅雨期有雷平均比率为0.26,虽比全年雨中有雷的平均比率(0.19)还高些,但比梅雨所在的6—7月雨中有雷平均比率(0.39)低得多。分析还发现雷与不同级别降水关系有差异,与小雨呈负相关,而与中雨、大雨和暴雨呈正相关,与暴雨的相关性最好,6—8月大雨和暴雨中有雷的比率高达0.62~0.74。

Analysis of relationship between thunderstorm and rain in Nanjing

Based on the thunderstorm days and precipitation data recorded by weather observation of Nanjing from 1951 to 2007, thunderstorm without rain, thunderstorm with rain and the probability of rain associated with thunderstorm were analyzed. Results showed that during the past 57 a the event of thunderstorm with rain is more frequent than thunderstorm without rain, both of them are decreasing, but thunderstorm with rain decreases more quickly, they both appear more frequent in summer than in winter. Most of rain associated with thunderstorm, daily probability of which is higher than 0.2, happened in July and August. The highest probability appears on July 20. The probability of rain associated with thunderstorm distributes from 0.12 to 0.25 with the average probability of 0.19, it is decreasing slowly, but the recent result displays an increasing tendency. Monthly variation of the probability shows a single peak in summer. Meanwhile, the probability of thunderstorm during Meiyu period was analyzed, using Meiyu data of 1961, the probability distributes widely, which is from 0 to 0.9, the average probability(0.26) is higher than that of the whole year(0.19) but lower than that of June and July(0.39) when Meiyu is concentrated. The correlation between thunderstorm and different kinds of precipitation differs with each other, it is negative correlation with light rain, but it positively correlated with moderate rain, heavy rain and rainstorms. The probability of rain associated with thunderstorm in heavy rain and rainstorms from June to August is up to 0.62 to 0.74.