中国长江流域洪涝灾害和持续性暴雨的发生特征及成因

主要综述了最近关于中国长江流域洪涝灾害和持续性暴雨发生特征和成因的研究。表明:长江流域洪涝灾害和持续性暴雨的发生频率非常高,并给经济造成了严重损失,长江流域洪涝灾害发生不仅具有准两年周期的年际变化,而且具有明显的年代际变化,从1977年之后,长江流域洪涝灾害和持续性暴雨增多;并且,表明了无论是长江中、下游地区或是长江上游的川东地区持续性暴雨都是在"鞍"型大尺度环流系统的配置下发生,这是由于这种大尺度环流系统的配置不仅利于水汽输送到长江中、下游地区或上游的川东地区,而且利于在"鞍"型中心地区产生垂直对流不稳定,从而引起暴雨中尺度系统的发展。此外,还综述了长江流域洪涝灾害和持续性暴雨发生的成因的研究,这些研究表明了长江流域洪涝灾害和持续性暴雨发生的年际和年代际变化是与大气-海洋-陆面耦合的东亚季风气候系统的变异密切相关。

Characteristics and Causes of the Occurrence of Flooding Disaster and Persistent Heavy Raifnall in the Yangtze River Valley of China

Our recent studies on characteristics and causes of the occurrence of flooding disaster and persistent heavy rainfall in the Yangtze River valley are mainly synthesized in this paper.These studies have shown that the occurring frequency of flooding disaster and persistent heavy rainfall in the Yangtze River valley is very high,which has caused serious economic loss in this valley.And the occurrences of flooding disaster are of not only an interannual variability with quasi-biennial period,but also an obvious intetrdecadal variability,i.e.,the occurring frequency of floodsing disaster and persisternt havey rainfall in the Yangtze River valley significantly increased after 1977.Moreover,these studies also showed that persistent heavy rainfall either in the middle and lover reaches or in the eastern Sichuan region of the upper reach of the Yangtyze River occur under the saddle pattern background of large-scale circulation.This may be due to that the pattern background of large-scale circulation is favorable not only to the transport of water vapor into the middle and lower reaches or the eastern Sichuan region of the upper reach of the Yangtze River,but also to the occurrence of the instability of vertical convection in the central region of the basckground circulation of the saddle pattern,which can cause the development of the middle-scale system of heavy rainfall.Besides,the studies on the causes of the interannual and interdecadal variations of the occurrence of flooding disaster and persistent heavy rainfall in the Yangtze River valley of China are also synthesized in this paper.These studies showed that the interannual and interdecadal variabilities of the occurrence of flooding disaster and persisternt heavy rainfall in the Yangtze River valley of China are closely associated with the variability and anomaly of the air-sea-land coupling East Asian monsoon climate system.