1976—2017年青海湖东北部地区极端降水事件变化特征分析

Extreme Precipitation Events in the Northeast of Qinghai Lake from 1976 to 2017:Variation Characteristics Analysis

为进一步了解高寒牧区气候变化,依据1976—2017年青海湖东北部海晏站逐日降水资料,采用百分位法确定冬、夏半年极端降雨(雪)阈值并统计极端降水事件,运用线性趋势、R/S和小波分析法分析极端降水事件变化特征、未来演变趋势及周期。结果表明:青海湖东北部地区冬、夏半年极端降水日数和极端降水量呈不显著增加趋势;冬半年极端降水强度和日最大降水量不显著增加,而夏半年不显著减小;极端降水对年降水的贡献率均以不同的速率增加,其中夏半年的极端降水对年降水的影响较大;冬半年降水日数不显著减小,而降水量显著增加,表明冬半年发生短时强降水的几率增大,夏半年的降水日数和降水量增加不明显;未来,冬半年极端降水日数增加趋势将发生转变,极端降水量与之前的变化趋势无关将继续呈现震荡性,其他各要素将持续前期的变化趋势;冬(夏)半年极端降水日数和降水量分别存在明显的周期变化特征。高寒牧区的极端降水研究对于预防短时强降水带来的雪灾、洪涝事件的发生意义重大。

To further understand the climate change in alpine pastoral areas,based on the daily precipitation data of Haiyan Station in the northeast of Qinghai Lake from 1976 to 2017,we determined the extreme precipitation(snow)threshold in winter(summer)half year and counted extreme precipitation events by using the percentile method,analyzed the variation characteristics,future trends and cycles of extreme precipitation events by linear trend,R/S and wavelet analysis.The results showed that:the extreme precipitation days and extreme precipitation in the northeastern of Qinghai Lake did not increase significantly in winter and summer half year;the extreme precipitation intensity and daily maximum precipitation did not increase significantly in winter half year,but did not decrease significantly in summer half year;the contribution rate of extreme precipitation to annual precipitation increased at different rates,and the extreme precipitation in summer half year had a greater impact on annual precipitation;the number of precipitation days in winter half year did not decrease significantly,while the precipitation increased significantly,indicating that the probability of shortterm heavy precipitation in winter half year increased,and the number of precipitation days and precipitation in summer half year were not obvious;in the future,the trend of increasing the number of extreme precipitation days in winter half year would change;the extreme precipitation would continue to show volatility irrespective of the previous trend,and other factors would continue to change in the early stage;the number of extreme precipitation days and precipitation in winter(summer)half year had obvious periodic variation characteristics.The study of extreme precipitation in alpine pastoral areas is of significance in preventing the occurrence of snowstorms and floods caused by short-term heavy precipitation.