The 2016 Summer Floods in China and Associated Physical Mechanisms:A Comparison with 1998  

作　　者：Yuan YUAN Hui GAO Weijing LI Yanju LIU Lijuan CHEN Bin ZHOU Yihui DING 

机构地区：[1]Laboratory for Climate Studies,National Climate Center,China Meteorological Administration [2]Collaborative Innovation Center on Forecast and Evaluation of Meteorological Disasters,Nanjing University of Information Science &Technology

出　　处：《Journal of Meteorological Research》2017年第2期261-277,共17页气象学报（英文版）

基　　金：Supported by the National(Key)Basic Research and Development(973)Program of China(2013CB430203);China Meteorological Administration Special Public Welfare Research Fund(GYHY201306033 and GYHY201406001);National Natural Science Foundation of China(41130960)

摘　　要：The characteristics of droughts and floods in China during the summers（May–August）of 2016 and 1998 were compared in great detail,together with the associated atmospheric circulations and external-forcing factors.Following results are obtained.（1）The precipitation was mostly above normal in China in summer 2016,with two main rainfall belts located in the Yangtze River valley（YRV）and North China.Compared with 1998,a similar rainfall belt was located over the YRV,with precipitation 100%and more above normal.However,the seasonal processes of Meiyu were different.A typical＂Secondary Meiyu＂occurred in 1998,whereas dry conditions dominated the YRV in2016.（2）During May–July 2016,the Ural high was weaker than normal,but it was stronger than normal in 1998.This difference resulted from fairly different distributions of sea surface temperature anomalies（SSTAs）over the North Atlantic Ocean during the preceding winter and spring of the two years.（3）Nonetheless,tropical and subtropical circulation systems were much more similar in May–July of 2016 and 1998.The circulation systems in both years were characterized by a stronger than normal and more westward-extending western Pacific subtropical high（WPSH）,a weaker than normal East Asian summer monsoon（EASM）,and anomalous convergence of moisture flux in the mid and lower reaches of the YRV.These similar circulation anomalies were attributed to the similar tropical SSTA pattern in the preceding seasons,i.e.,the super El Ni？o and strong warming in the tropical Indian Ocean.（4）Significant differences in the circulation pattern were observed in August between the two years.The WPSH broke up in August 2016,with its western part being combined with the continental high and persistently dominating eastern China.The EASM suddenly became stronger,and dry conditions prevailed in the YRV.On the contrary,the EASM was weaker in August 1998 and the＂Secondary Meiyu＂took place in the YRV.The Madden–Julian Oscillation（MJO）was extremely actThe characteristics of droughts and floods in China during the summers（May–August）of 2016 and 1998 were compared in great detail,together with the associated atmospheric circulations and external-forcing factors.Following results are obtained.（1）The precipitation was mostly above normal in China in summer 2016,with two main rainfall belts located in the Yangtze River valley（YRV）and North China.Compared with 1998,a similar rainfall belt was located over the YRV,with precipitation 100%and more above normal.However,the seasonal processes of Meiyu were different.A typical＂Secondary Meiyu＂occurred in 1998,whereas dry conditions dominated the YRV in2016.（2）During May–July 2016,the Ural high was weaker than normal,but it was stronger than normal in 1998.This difference resulted from fairly different distributions of sea surface temperature anomalies（SSTAs）over the North Atlantic Ocean during the preceding winter and spring of the two years.（3）Nonetheless,tropical and subtropical circulation systems were much more similar in May–July of 2016 and 1998.The circulation systems in both years were characterized by a stronger than normal and more westward-extending western Pacific subtropical high（WPSH）,a weaker than normal East Asian summer monsoon（EASM）,and anomalous convergence of moisture flux in the mid and lower reaches of the YRV.These similar circulation anomalies were attributed to the similar tropical SSTA pattern in the preceding seasons,i.e.,the super El Ni？o and strong warming in the tropical Indian Ocean.（4）Significant differences in the circulation pattern were observed in August between the two years.The WPSH broke up in August 2016,with its western part being combined with the continental high and persistently dominating eastern China.The EASM suddenly became stronger,and dry conditions prevailed in the YRV.On the contrary,the EASM was weaker in August 1998 and the＂Secondary Meiyu＂took place in the YRV.The Madden–Julian Oscillation（MJO）was extremely act

关 键 词：summer precipitation FLOODING Yangtze River valley super El Ni?o SST anomaly tropical Indian Ocean snow cover over the Qinghai–Tibetan Plateau Madden–Julian Oscillation 

分 类 号：P426.616[天文地球—大气科学及气象学]