甘肃省极端降水指数时空变化特征

Characteristics of Temporal and Spatial Variation of Extreme Precipitation Index in Gansu Province

为了明确甘肃省极端降水事件的时空发生规律和变化特征,根据气候变化监测与指数专家组(ETCCDI)推荐的11个极端降水指数,分析了极端降水指数的时间变化特征,基于GIS技术采用空间地统计方法,研究了极端降水指数空间分布特征。结果表明:在时间分布上,持续干期呈显著减弱,变化速率为-2.129(p<0.05),持续湿期微弱下降,变化速率为-0.005(p<0.05),其余10个极端降水指数呈增强趋势(p<0.05),尤其年降水总量增加显著,变化速率为2.56(p<0.05)。总体来看,极端指数变化存在明显周期性,大致可分为2~3个周期;突变多发生在20世纪60年代中后期。在空间分布上,全省极端降水指数的空间变化特征较为明显,包括年降水量在内的10个极端指数由河西走廊向东递增,持续干期与之相反。综上,甘肃省极端降水指数变化具有明显的时间和空间差异。

In order to clarify the temporal and spatial regularity and variation characteristics of extreme precipitation events in Gansu Province,based on the daily precipitation data of 23 meteorological stations in Gansu Province,11 extreme precipitation indexes recommended by the Expert Group on Climate Change Monitoring and Indexes(ETCCDI)were selected,and the temporal change characteristics of extreme precipitation indexes were analyzed.Statistical methods were used to study the spatial distribution characteristics of extreme precipitation indices.The results show that:in terms of time distribution,the continuous dry period in Gansu Province had being significantly weakened,the continuous wet period had decreased slightly,and the remaining 10 extreme precipitation indexes showed an increasing trend,especially the total annual precipitation had increased significantly;on the whole,the extreme index changes had obvious periodicity,which could be roughly divided into 2 to 3 periods;sudden changes mostly which occurred in the middle and late 1960s;in terms of spatial distribution,the extreme precipitation index of Gansu Province had obvious spatial variation characteristics;the 10 extreme indexes,including annual precipitation,increased eastward from the Hexi Corridor,and the opposite was true for the continuous dry period.In conclusion,there are obvious temporal and spatial differences in the changes of extreme precipitation index in Gansu Province.