黄河流域极端降水时空分布特征及其影响因素

Spatiotemporal Distribution of Precipitation Extremes and Related Implications Across the Yellow River Basin,China

利用黄河流域77个气象站点1957-2014年日降水数据,基于超阈值(POT)的极端降水事件抽样、变异分析、趋势分析等方法分析了黄河流域极端降水的量级、频率和发生时间及夏季气温的时空分布特征及其影响因素.结果表明:黄河流域极端降水量级存在显著变异特征,但不存在显著趋势变化;极端降水频率呈逐年上升或显著上升趋势,表明黄河流域发生极端降水的次数增加,但降水量减少;黄河流域南部极端降水发生时间有推迟的趋势.该流域夏季温度存在显著变异特征,变异时间大部分在1980年以后,大部分站点的夏季温度呈上升或显著上升趋势,对极端降水的频率有重要的正相关影响;流域西北部极端降水频率在夏季温度转折点后有明显增高趋势,流域内大部分站点极端降水发生时间在夏季温度转折前后都呈上升趋势.

Based on the daily precipitation and temperature data at 77 stations from 1957 to 2014over the Yellow River Basin,spatiotemporal patterns of precipitation extremes were characterized in terms of magnitude,frequency and occurrence timing as well as the influence of summer temperature.Precipitation extremes in this study were defined based on Peak over Threshold（POT）sampling method and changing properties were quantified using change point analysis,trend analysis.The results indicated that the magnitude of extreme precipitation is subject to evident alterations without significant trends.Frequency of precipitation extremes is subject to adverse this,and it exists increasing or significant increasing trends which implies that the frequency of extreme precipitation is rising while the amount of precipitation is decreasing.The occurrence timing of extreme precipitation in the southern part of the Yellow River Basin follows significant increasing or increasing trends,implying that occurrence of precipitation extremes comes to be later or delayed.The summer temperature exists evident alterations and most happened after 1980,and most part of the basin follows increasing or significant increasing trends,which has a significant positive correlation with the frequency of the extreme precipitation.The extreme precipitation frequency in the northwestern part of the basin has a tendency to increase after the turning point of summer temperature,and the occurrence timing of extreme precipitation in most sites of the basin is delaying before and after the summer temperature change.