1931年与2020年安徽省长江流域异常降水的对比分析

Comparison of Abnormal Rainfall in Yangtze River Basin in Anhui Between 1931 and 2020

利用世界百年气象站——芜湖站以及安徽省气象档案馆提供的1931年降水量数据及2020年逐日降水数据,对1931年与2020年安徽省长江流域异常降水进行了对比分析。研究表明,1931年与2020年汛期强降水时段和降水强度差异显著。1931年7月异常降水最为显著,2020年异常降水主要集中在6—7月。2020年汛期强降水比1931年总雨量更大、维持时间更长、降水时段更加集中。1931年7月与2020年7月安徽长江流域全区域降水变化一致,上下游降水的峰值相重叠,导致长江水位节节升高。1931年7月与2020年6月鄂霍次克海地区的地面上均维持强盛的冷高压,为下游输送冷空气,安徽—日本地区存在低压槽,有利于冷暖空气长期交汇在安徽长江流域。2020年7月冷空气主要来源于河套地区和东北地区,副热带高压偏南偏强,在安徽长江流域继续维持稳定少动的梅雨锋。2020年虽然洪涝灾害更严重,但人员伤亡却大大减少,抗洪抢险的胜利充分彰显了社会主义制度的优越性。

Based on the precipitation data from the World Centennial Meteorological Station in Wuhu,daily precipitation data in 2020 and the precipitation data in 1931 provided by Anhui Meteorological Archives,differences of abnormal rainfall between the summers in 1931 and 2020 were compared.Results showed the differences of the precipitation intensity and heavy rain periods were significant.Precipitation in 1931 was concentrated in July while precipitation was mainly in June and July 2020.Compared to 1931,the year 2020 witnessed not only greater amount but also longer period of heavy rainfall.Heavy rain periods were highly consistent in the whole Yangtze River Basin in Anhui both in 1931 and in 2020,so flood peak in upper and lower reaches were overlapping,resulting in rapid rising of water level in the Yangtze River.There was strong cold high over Okhotsk Sea in July 1931 and June 2020,which could transport cold air to East China.Meanwhile the low pressure trough over Anhui-Japan was favorable for the warm air and cold air to converge over the Yangtze River Basin in Anhui,bringing persistent precipitation over an extensive area.The cold air came from Hetao Region and Northeast China in July 2020 and the subtropical high was stronger and further south than usual,leading to a stable Mei-yu front over the Yangtze River Basin in Anhui.Although flood disaster in 2020 was severer,casualties were greatly reduced.The great victory of flood rescue fully demonstrated the superiority of the socialist system.