城市化背景下长三角核心城市群汛期降水时空演变特征分析

Temporal and spatial evolution characteristics analysis of flood season precipitation in core city group of the Yangtze River delta under background of urbanization

为揭示城市化背景下长三角核心城市群汛期降水的时空演变规律,基于1978—2021年长三角核心城市群42个雨量站的小时降水数据,探究了汛期降水时空变化特征以及城市化对汛期降水的影响规律。结果表明:在空间分布上,汛期极端降水阈值呈现从北向南逐渐减小的趋势;在时间尺度上,研究区汛期降水总体呈显著增加趋势,后汛期降水变化在整个汛期降水变化中占主导地位;城区降水的增速基本高于郊区,苏浙沪城区和郊区汛期总降水量的增长率均呈现递减趋势;城市化对上海城郊降水差异的影响更为显著,对不同降水指标的城郊差异影响程度表现为后汛期极端降水量最大、汛期极端降水量次之、汛期总降水量最小。

In order to reveal the temporal and spatial evolution law of precipitation during flood season in the core city group of the Yangtze River delta under the background of urbanization,based on the hourly precipitation data of 42 rainfall stations in the study area from 1978 to 2021,the temporal and spatial variation characteristics of precipitation in the flood season and the impact law of urbanization on precipitation were explored.The results show that,in terms of spatial distribution,the threshold value of extreme precipitation in the flood season gradually decreases from north to south;in terms of time scale,the precipitation in the study area in the flood season generally shows a significant increase trend,and the precipitation changes in the post-flood season dominate the precipitation changes in the entire flood season;the increase rate of precipitation in urban areas is basically higher than that in suburban areas,and the growth rate of total precipitation during the flood season in urban areas and suburban areas of Jiangsu,Zhejiang,and Shanghai shows a decreasing trend;Urbanization has a more significant impact on the rainfall variation between urban and suburban areas in Shanghai.The impact degree on the difference between urban and suburban areas of different precipitation indicators is the largest for the extreme precipitation in the post-flood season,followed by the extreme precipitation in the flood season,and the smallest for total precipitation in the flood season.