近50年天水市雷暴日数的时空分布特征

利用1964 ～2013年天水市7个测站的逐日雷暴观测资料,对天水雷暴天气的分布情况、年际变化及雷暴地域变化特征等进行了统计分析,结果表明,近50年天水市各站年平均雷暴日数为13.7 ～26.6 d;主汛期（4～9月）雷暴出现日数占全年雷暴总日数的96％,雷暴日数的月变化呈单峰型,其中主峰集中在5～8月,占全年雷暴总日数的81％,冬季几乎不出现;平均雷暴初日、终日分别出现在4月下旬和9月下旬,平均雷暴初终间日数为157 d;天水各站雷暴日数逐年总体呈减少趋势,且与海拔高度呈明显的正相关,自西南向东北方向逐渐增多.

Characteristics of Spatial and Temporal Distribution of Thunderstorm Days in Tianshui in Recent 50 Years

Based on data of thunderstorm days in 7 weather stations located in Tianshui City in recent 50 years （1964-2013）,this paper made a statistical analysis on the inter-annual variation,distribution and regional characteristics of thunderstorm days.The results showed that the annual thunderstorm days ranged from 13.7 to 26.6 days and 96％ of them appeared in major flood period from April to September,and the month variation take on a single peak type.It also indicated that 81％ of thunderstorm days appeared from May to August.The first thunderstorm day appeared in the last ten days in April and that the last day ended in last ten days in September.There are 157 days between the first and the last thunderstorm day.The thunderstorm days showed a positive correlation with elevation and took on a decreasing trend with time and an increasing trend from southwest to northeast.