1991—2020年甘南州主要极端气候指数变化趋势

Change Trend of Main Extreme Climate Indexes in Gannan Prefecture from 1991 to 2020

利用1991—2020年甘南藏族自治州8个国家级气象站逐日气温和降水资料,计算极端气候指数,并运用趋势分析法、Morlet复小波分析法对相关指数的变化特征进行分析。结果表明:在甘南州7个极端气温指数中,暖昼等暖指数呈上升趋势,冷夜等冷指数趋于下降,且冷夜下降趋势比暖昼上升趋势更显著,3个降水指数均呈增加趋势,说明甘南州有明显的变湿、变暖倾向,且极端降水事件频次增加。极端气温指数大多在20世纪90年代中后期出现突变。极端降水指数周期特征明显,存在着10年和6年附近的周期。

Based on the daily temperature and precipitation data of eight national meteorological stations in Gannan Tibetan Autonomous Prefecture from 1991 to 2020,the extreme climate index was calculated,and the change characteristics of the relevant index were analyzed using trend analysis and Morlet complex wavelet analysis.The results show that among the seven extreme temperature indexes in Gannan Prefecture,the warm day isoparametric index shows an upward trend,and the cold night isoparametric index tends to decline,and the cold night decline trend was more significant than the warm day rise trend,and the three precipitation indexes show an upward trend,indicating that Gannan Prefecture has an obvious trend of wetting and warming,and the frequency of extreme precipitation events increases.Most of the extreme temperature indexes changed abruptly in the middle and late 1990s.The cycle characteristics of extreme precipitation index are obvious,and there are periods around 10 a and 6 a.