海南雷暴气候特征及大气环流背景分析

Climatic Changes Related to Thunderstorm Days in Hainan and Analysis of Atmospheric Circulation Background

利用1966～2005年海南地区18个市、县逐日雷暴观测资料及NECP再分析资料和EOF分析方法,分析了海南地区雷暴天气的气候特征及其气候变化的可能影响因素。结果表明：海南雷暴的年际变化呈较明显的下降趋势;空间分布主要呈现北部内陆地区多、南部沿海地区少的特点;全省雷暴集中发生在4～10月,盛发期在5～9月;雷暴异常年5～9月平均大气环流与同期500 hPa大气环流特征的关系表现在雷暴频繁年低纬地区的位势高度距平场出现大范围的负距平,当年夏季西太平洋副热带高压较弱,位置偏东,雷暴偏少年则副高较强,脊线偏西。不稳定因子K指数和TT指数对海南的雷暴有一定预报能力。

The climate characteristics of thunderstorms at 18 stations in Hainan from 1966 to 2005 are analyzed using the EOF （Empirical Orthogonal Function） method. The results indicate that there was a decreasing tendency in the thunderstorm frequency in Hainan from 1966 to 2005; there occurred less thunderstorms in the south coastal area and more in the north inland areas; thunderstorm days were mainly concentrated in the period from April to October with the peak between May and September; in abnormal thunderstorm years, an obvious negative anomaly existed in low latitude areas at 500 hPa from May to September; the subtropical high is relatively weak and farther east in active thunderstorm years, and vice verse in less active thunderstorm years. K-index and TT-index are also analyzed, and the results show that they have certain prediction ability for thunderstorms.