松辽流域1961-2017年极端降水变化特征

为了在气候变暖的背景下有的放矢地防御流域洪涝灾害，根据1961—2017年松辽流域逐日降水资料，采用百分位数、距平累积、Mann-Kendall、变差系数等方法分析了松辽流域极端降水变化特征。结果表明:松辽流域极端降水阈值呈西北小、南部大的分布；松辽流域极端降水量和降水频率都是由西北向东南升高，极端降水强度呈中南部大、其他地方小的分布，极端降水比率则由西北向东南降低；极端降水指数呈西南部低东北部高的趋势。极端降水主要发生在夏季；20世纪60年代初期开始极端降水指数存在由强转弱的突变，80年代中期以后开始增强，目前处于偏强阶段；1961—2017年及突变前极端降水量及频率呈上升的趋势，极端降水强度和比率则呈下降的趋势，气温突变后极端降水指数都呈下降的趋势，变差系数增大。目前松辽流域处于极端降水偏强阶段，极端降水量大，频率高，强度大，且变差系数增大，不稳定增强，极端降水发生的几率增加，因此应引起高度重视，加强相关研究，提高对极端降水灾害的防范和应对能力。

Characteristics of Extreme Precipitation Change from 1961 to 2017 in Songliao Basin

In order to protect against floods and waterlogging in the background of climate warming, according to the daily precipitation data of Songliao Basin from 1961 to 2017, the characteristics of extreme precipitation in Songliao Rver Basin were analyzed by means of percentile, anomaly accumulation, Mann-Kendall, variation coefficient and so on. The results showed that the extreme precipitation threshold in Songliao basin was small in the northwest and large in the south; the extreme precipitation and precipitation frequency in Songliao basin were increasing from northwest to southeast, and the intensity of extreme precipitation was large in the middle and south and small in other places, and the ratio of extreme precipitation decreased from northwest to southeast, the extreme precipitation index mostly presentedthe trend of declining in the southwest and rising in the northeast; extreme precipitation mainly occurred in summer, accounting for 81.8% of the total number; at the beginning of the 1960s, the extreme precipitation index changed from strong to weak level, which began to strengthen after the mid-1980s and is in a strong phase now; the extreme precipitation and precipitation frequency increased from 1961 to 2017, but the intensity and ratio of extreme precipitation decreased; after the abrupt change of temperature, the extreme precipitation index decreased, and the coefficient of variation increased; at present, the extreme precipitation in Songliao Bbasin is at a strong stage, the extreme precipitation is large, the frequency is high, the intensity is large, and the variation coefficients of extreme precipitation index are increased after mutation, and instability and probability of extreme precipitation increase. Therefore, the extreme precipitation should be highly valued, relevant research should be strengthened in order to improve prevention and response ability.