2007—2020年四川省极端降水的时空演变特征

Spatial and temporal variations of extreme precipitation in Sichuan Province from 2007 to 2020

近年来四川省极端降水频发造成了巨大的经济和人员损失,充分了解极端降水的变化规律对管理和减轻极端降水所造成的损失有重要意义.利用四川省2007—2020年145个气象台站逐日降水资料,选择了6个极端降水指数分析四川省极端降水的时空演变特征.结果表明,在空间上,各极端降水指数数值在川东北和盆地西部地区最大,其变化趋势也有明显的地域差异.各极端降水指数在川东北地区明显减少,盆地西部明显增加,其余地区大部分站点呈增加趋势,只有少数站点呈减少趋势.时间上,四川省极端降水指数均呈增加趋势,极端降水有增强趋势.四川省3个子区域中的盆地中西部和西部高海拔地区极端降水变化和四川全省类似,川东北地区除年总降水量外,其余指数均减少,极端降水有明显减弱.四川省极端降水贡献率有增加趋势,降水极端性有所增强,尤其在2017—2020年间降水最为极端;盆地中西部地区极端降水贡献率的变化与四川全省类似,川东北地区与之相反,西部高海拔地区有缓慢增加.四川省在春季、夏季和秋季降水量增多,极端降水总量在夏季有明显增加;夏季极端总降水量和强度在8月增加最为明显,而在7月呈减少趋势,极端降水在8月最为强烈.

In recent years,frequent occurrences of extreme precipitation in Sichuan Province have caused huge economic and personnel losses.A comprehensive understanding of the regular pattern of extreme precipitation is of vital importance for managing and reducing the losses caused by extreme precipitation.Based on the daily precipitation data from 145 meteorological stations in Sichuan Province from 2007 to 2020,six extreme precipitation indexes were used to analyze the temporal and spatial variations of extreme precipitation in Sichuan Province.The results are as follows:Spatially,the values of extreme precipitation indexes were the largest in northeastern Sichuan Province and the western part of the Sichuan Basin,and the variation trends presented obvious geographical differences.Extreme precipitation indexes showed a significant decrease trend in northeastern Sichuan Province and an opposite trend in the western part of the Sichuan Basin;most stations in the rest regions displayed an obvious increase trend;And only a few stations displayed a decrease trend.Temporally,all the extreme precipitation indexes in Sichuan demonstrated an increasing trend,which means extreme precipitation has an increasing trend in the province.In the three sub-regions of Sichuan Province—the central and western parts of the basin and the western high-altitude area—the variations of extreme precipitation were similar to those of the whole Province;In northeastern Sichuan,the other indexes of extreme precipitation decreased except PRCPTOT,and extreme precipitation significantly decreased.The contribution rate of extreme precipitation to the total precipitation in Sichuan Province showed an increase trend,and the precipitation became more extreme,especially from 2017 to 2020.The trend of the contribution rate in the central and western parts of the basin was similar to that of the whole province,while the contribution rate in northeastern Sichuan had an opposite trend.Besides,the trend of the contribution rate in the western high-altitude area increased slowly.Precipitation in Sichuan Province increased in spring,summer and autumn,meanwhile the total extreme precipitation obviously increased in summer.Moreover,the amount and intensity of extreme precipitation reached their peaks in August while showing a decrease trend in July.To sum up,the extreme precipitation in Sichuan Province is the heaviest in August.