A DYNAMIC MODE FOR RELATIONSHIP BETWEEN FLOOD/DROUGHT IN YANGTZE RIVER VALLEY AND LOW FREQUENCY WAVE ORIGINATED FROM TROPICAL SEA AREA

According to statistic analysis on sea surface temperature(SST) anomaly features in the North Pacific in winters and springs prior to the summer flood/drought in the middle and lower reaches of the Yangtze River(hereafter referred to as MLRY),a strong signal SST key area that affects local flood/drought is put forward,that is the equatorial eastern Pacific.The response of general circulation in the Northern Hemisphere to SST anomaly in the key area is further investigated.The low frequency wave train structure of correlation between the eastern Pacific SST and the height at 500 hPa in the Northern Hemisphere is also studied,which reflects the dynamic features of teleresponse of local flood/drought at extratropics to tropical SST anomaly.Through introducing SST anomaly in the strong signal area in numerical experiments,the flood in Yangtze River Valley is successfully simulated and the similar wave train pattern in the flow field is obtained too.Altogether,the physical picture and dynamic mode of the flood in the Yangtze River Valley are described in this work.