近53年长三角地区极端降水时空变化分析

Spatio-temporal Variations of Extreme Precipitation in the Yangtze River Delta during 1960-2012

近年来,全球气候变暖趋势越来越明显,极端降水加剧了长江流域的旱涝灾害风险。利用长三角地区34个气象站1960—2012年逐日降水资料,以百分位定义极端降水事件阈值,采用趋势分析、Mann-Kendall检验、GIS空间分析等方法,在资料均一性检验和资料质量控制后,对长三角地区近53a的极端降水的时空演变特征进行了详细分析,结果表明：1长三角极端降水阈值分布在30.7-46.7之间且都在大雨范围内,部分站点接近暴雨级别,分布呈现带状分布,苏北、浙西南和浙东南沿海部分站点极端降水阈值较大,而苏南、浙北以及上海一带较小;2极端降水频次和强度存在明显的年代际差异,表现为前期明显下降而后期缓慢上升的趋势,长三角降水变得更为异常,极端降水突变主要发生在1987年;3浙江西南部和东南沿海岛屿的极端降水频次和总量均较高,R95T大值区主要分布在苏北以及浙江东南沿海;4极端降水频次的四季变化体现了一年中雨带的南北移动,同时也体现了沿海与内陆的降水差异;苏北赣榆站、浙江东部沿海及岛屿站点的降水变得较为极端,未来易发生暴雨和洪涝,而射阳及周围地区发生干旱的几率增大。

In recent years,the trend of global warming has been more and more serious,and extreme precipitation contributed to the risk of drought and flood disaster in the Yangtze River basin. Daily precipitation data of 34 auto-matic meteorological stations in the Yangtze River delta region from 1960-2012 were used to investigate the features of spatial and temporal variations of extreme precipitation using methods of the trend analysis, Mann-Kendall test and GIS spatial analysis. The main conclusions are as follows： 1） the extreme precipitation threshold limit value was in the range between 30. 7mm and 46. 7mm,all are heavy rainfall,and some close to rainstorm. The extreme precipitation threshold value presents zonal distribution features, large in north Jiangsu, southwest and southeast Zhejiang,and small in south Jiangsu,north Zhejiang, and Shanghai; 2） the frequency and intensity of extreme precipitation has obvious interdecadal differences,characterized by trends of decreasing obviously in early stage and slowly rising in late stage. The precipitation in the Yangtze River delta was more abnormal,and the extreme precipitation mutations mainly occurred in 1987; 3） the frequency and total amount of extreme precipitation were high in the southwest and southeast coastal islands of Zhejiang,and the value of R95T was large mainly in north Jiangsu and Zhejiang’s southeast coastal areas; 4） the seasonal change of extreme precipitation frequency reflected the northsouth movement of the rain belt in a year,and also reflected the precipitation differences between the coast and the inland. The study also found that the precipitation events in Ganyu station of north Jiangsu,and stations on eastern Zhejiang’s coast and island had become extreme,with rainstorm and flooding likely to happen in the future. The probability of drought in Sheyang and its surrounding areas will increase.