气候变暖背景下中国沿海降水变化特征

The precipitation changes in the coastal areas of China under the background of global climate warming

IPCC第六次评估报告指出,随着全球变暖,强降水事件通常会变得更加频繁和强烈。暴雨是我国主要气象灾害之一,是引发洪涝的最主要原因。目前洪涝灾害已成为影响滨海城市公共安全和经济社会发展的重要因素,了解降水的变化特征对于科学应对气候变化和防灾减灾具有重要意义。本文研究结果显示,1966-2020年中国沿海降水量和暴雨及以上级别降水日数(日降水量≥50 mm的日数)总体均呈增多趋势,但变化趋势不显著;降水日数(日降水量≥0.1 mm的日数)总体呈减少趋势,且变化趋势显著。降水量和暴雨及以上级别降水日数在长江口至福建北部沿海和海南沿海增加趋势明显,山东省及以北沿海、广东省东部沿海呈减少趋势;降水日数除在长江口附近呈增多趋势外,其他沿海地区均以减少为主。降水日数总体减少,降水量总体增多,表明降水过程中降水强度有增加趋势。中国沿海总体暴雨及以上级别强降水主要集中在5-9月,出现频率占全年81.7%。多地出现最大日降水量超过250 mm情况,局部最大日降水量超过500 mm。强降水过程期间往往伴随高海平面,影响滨海城市行洪排涝,增加淹没风险。

The report of the WG1 of IPCC AR6 pointed out that with the global warming,heavy precipitation usually becomes more frequent and intense.Rainstorm is one of the major meteorological disasters in China,and it is the main cause of floods.At present,flood disaster has become an important factor affecting public safety and economic and social development of coastal cities.It is of great significance to learn the change of precipitations and heavy precipitations for response to climate change and disaster prevention and reduction.The study results showed that,from 1966 to 2020,the precipitation and rainstorm days(daily precipitation≥50 mm)in the coastal areas of China were generally increasing failed the significance test(α=0.05),the precipitation days(daily precipitation≥0.1 mm)were decreasing passed the significance test(α=0.05),and there were regional differences.Among them,the precipitations and the numbers of rainstorm days increased obviously from the Yangtze River estuary to the northern coast of Fujian and Hainan coast,and decreased in the north to the coastal areas of Shandong and the coastal areas of the eastern Guangdong.The precipitation days increased only in the Yangtze River estuary,while decreased in all the other coastal areas.The increasing of precipitations with the decreasing of the precipitation days means that the precipitation processes are intensifying.The rainstorms in the coastal areas of China were mainly concentrated from May to September,with the frequency accounting for 81.7%of the whole year.In many coastal areas of China,the maximum daily precipitations were more than 250 mm,and some local maximum daily precipitations were more than 500 mm.The rainstorm processes were usually with positive sea level anomalies,which affected the flood discharge and drainage of coastal cities and increased the risk of inundation.