天水市雷暴气候特征分析

为了研究天水市雷暴气候变化特征、周期性规律和时空分布特征,利用天水市7个观测站1971～2010年雷暴日资料,通过数理统计、Mann-Kendall检验、小波分析和EOF分析等方法分析近40年天水市雷暴气候特征。结果表明,天水市年平均雷暴日数为19.2 d,一年中雷暴发生在4～10月,7、8月份最多,雷暴主要发生在夏季;过去的40年,雷暴日数呈波动减少趋势,气候倾向率为-1.152d/10a;Mann-Kendall检验得出,在1995年天水雷暴日数开始明显减少,突变点出现在2008年,2008年后雷暴日数显著减少;Morlet小波分析结果表明,天水市雷暴日数同时存在3、6、12及22年的准周期变化;根据EOF分析,天水雷暴异常空间分布可划分为全市一致型和经向型,其中关山区雷暴日数最多,其次是渭北区,河谷区最少。

Analysis on Climatic Variation Characteristics of Thunderstorm in Tianshui City

In order to study the climatic variation characteristics,periodicity features,temporal-spatial distribution characteristics of thunderstorms in Tianshui City,using the observation thunderstorm data of 7 stations in Tianshui during 1971-2010,through mathematical statistics, Mann-Kendall test,wavelet analysis and EOF analysis method to analyze the climatic characteristics of thunderstorm in recent 40 years. The results show that the annual number of thunderstorm days is 19. 2 d in Tianshui City and it can occur 4 to 10 months in the year,mostly in July and August and in summer. Over the past 40 years,thunderstorm days showed a trend of fluctuations to reduce and climate tendency rate was-1. 152 d / 10 a. The results of Mann-Kendall test show that thunderstorm days began to decrease in Tianshui in 1995,a mutation point in 2008,2008 years after the thunderstorm days significantly reduced. Morlet wavelet analysis results show that thunderstorm days in Tianshui City at the same time there are 3,6,12 and 22 a quasi periodic change. The analysis of EOF shows that the abnormal spatial distribution of thunderstorm in Tianshui can be classified into two types： overall type and longitude type.