延安市安塞区极端降水变化特征

Characteristics of extreme precipitation in Ansai District of Yan’an City,China

以1980—2019年安塞气象站的日降水资料为基础选取11个极端降水指标,从降水强度和降水频率的角度对安塞区的极端降水数据进行分析,并对未来极端降水趋势进行预测。结果表明:1980—2019年,安塞区极端降水指标总体呈现下降趋势,其中,大雨以上日数和普通日降水强度的下降趋势达到显著水平,其气候倾向斜率分别为-0.65 d·(10 a)^(-1)和-0.32 mm·d^(-1)·(10 a)^(-1)。除持续湿润日数和极端降水总量外,其余极端降水指标均存在突变点,突变之后各指标多呈下降趋势,且年降水量、中雨以上日数、大雨以上日数、暴雨以上日数、异常降水总量、普通日降水强度的下降趋势达到显著水平。持续干燥日数与其他指标的相关性较低且与一些指标呈负相关,而持续湿润日数只与少数几个指标具有相关性,此外,其他极端降水指标之间均呈显著相关。Hurst指数分析表明,未来安塞区极端降水总体变化趋势具有持续性。

The extreme precipitation characteristics of Ansai District in 40 years was analyzed from the perspective of precipitation intensity and precipitation frequency with 11 extreme precipitation indices,based on daily precipitation data of Ansai Meteorological Station from 1980 to 2019.The trend of extreme precipitation in the future was predicted.The results showed that the extreme precipitation indicators generally showed a downward trend during 1980-2019.The downtrend of heavy precipitation days and simple daily precipitation intensity reached significant level,with their climate tendency slopes being-0.65 d·(10 a)^(-1),-0.32 mm·d^(-1)·(10 a)^(-1),respectively.Except for consecutive wet days and extremely wet day precipitation,the other extreme precipitation indices had mutation points.After the mutation,most of them had a downward trend,with significant decreases of annual precipitation,moderate precipitation days,heavy precipitation days,very heavy precipitation days,very wet day precipitation,simple daily precipitation intensity.The correlation between the consecutive dry days and other indicators was low and negatively correlated with some indicators,while the consecutive wet days were only correlated with a few indicators.In addition,other extreme precipitation indicators were significantly correlated.Results of the Hurst index analysis showed that the trend of extreme precipitation in Ansai District was sustainable.