Abstract:

Based on the hourly thunderstorm observation data in Kelan of Shanxi and NCEP reanalysis data during 1970-2014, the climate characteristics of thunderstorms were analyzed statistically by using linear tendency estimation, Morlet wavelet analysis and Mann-Kendall test, the characteristics of mean atmospheric circulation and convective stability from June to August in the years with severe thunderstorms during 1970-2014 were discussed by using composite analysis. The results are as follows: (1) The seasonal and time characteristics of thunderstorm in Kelan of Shanxi were very obvious during 1970-2014, the thunderstorm mainly occurred from June to August, which accounted for about 74.08% of the total, and it mainly occurred from 13:00 to 21:00, which accounted for about 66.46%. The annual thunderstorm days presented an increasing trend on the whole in the past 45 years, and the climatic tendency rate was 1.8 d·(10 a)-1. The initial date of thunderstorm in Kelan was 25 March, while the ending date of thunderstorm was 3 November, and the annual variations of the initial and ending dates of thunderstorm were great during 1970-2014. (2) The significant periods of thunderstorm days during 1970-2014 were 2.4570 a and 4.1322 a. (3) On 500 hPa geopotential height and anomaly fields, the Kelan of Shanxi located at the bottom of trough in active thunderstorm years, while it located in the northwest airflow behind the trough in less active thunderstorm years. (4) The value of CAPE was 229.701 J·kg-1 in active thunderstorm years, and it was 2.0191 times of that in less active thunderstorm years, and the value of K-index in active thunderstorm years was 31.5934 ℃, and it was lightly larger than that in less active thunderstorm years, which indicated that the atmosphere was more unstable in active thunderstorm years.

Key words: thunderstorm, climate characteristics, wavelet analysis, circulation background, Kelan  

摘要：

利用1970—2014年山西省岢岚地区地面雷暴观测资料及NCEP再分析资料，统计分析岢岚地区雷暴的气候特征，并研究雷暴严重年6—8月平均大气环流和对流稳定性特征。结果表明：（1）1970—2014年山西岢岚地区雷暴活动具有很强的季节性、时间性特征，主要集中在6—8月（占总数的74.08%）、13:00—21:00（占总数的66.46%）；年雷暴日数呈增多趋势，每10 a约增加1.8 d，雷暴初日最早出现于3月25日，终日最晚出现在11月3日，且初、终日的年际差异较大；（2）小波分析结果显示，近45 a岢岚地区年雷暴日数具有明显的2.457 a和4.1322 a周期变化特征；（3）多雷暴年，岢岚地区位于500 hPa平均位势高度及距平场槽底，而少雷暴年则位于槽后脊前；（4）多雷暴年的CAPE值为229.70 J·kg-1，是少雷暴年的2.0191倍，多雷暴年的K指数值达31.6 ℃，比少雷暴年大2.83 ℃，表明多雷暴年大气的不稳定性程度更高。

关键词: 雷暴, 气候特征, 小波分析, 环流背景, 岢岚