The Climatic Characteristic Of Atlantic Ni?o And Its Association With Summer Precipitation Anomaly In China

The variation of summer Atlantic Ni?o and its association with summer precipitation in China were investigated based on National Centers for Environmental Prediction Department of Energy(NCEP-DOE)Atmospheric Model Intercomparison Project Phase-?(AMIP-?)reanalysis data,sea surface temperature(SST)of The UK Met Office Hadley Centre,the observed rainfall data of 160 stations in China for the period of 1979?2014 by using statistical diagnosis methods,such as empirical orthogonal function(EOF)analysis,regression analysis etc.,and numerical simulation based on National Center for Atmospheric Research(NCAR)Community Atmosphere Model version 5(CAM5).The results are summarized as follows:(1)The Atlantic Ni?o is most obvious in summer.The Atlantic Ni?o in summer is the first mode of EOF in the tropical Atlantic SSTA,which revealed 33,7%variance,with apparent inter-annual variation.It has an inter-annual variation with 2-4a periods from the mid-1980s to the end of the 20th century,but no significant inter-decadal variation.(2)The Atlantic Ni?o in summer has an important influence on summer precipitation anomaly in China.When the Atlantic Ni?o is warm in summer,there are positive precipitation anomalies in the Yangtze River basin and northern China,with negative precipitation anomalies in southeastern periphery of China.The precipitation in the Yangtze River basin and north China has increased by about 20 percent over the same period as the summer Atlantic Ni?o index increases one standard deviation,while the precipitation in the southeastern periphery of China has decreased by about 20 percent,and vice versa.(3)When the Atlantic Ni?o is warm in summer,the appearance of an anomalous anticyclone over western North Pacific in the lower troposphere intensifies the Western Pacific subtropical high and makes it shift westward.The associated southwest wind anomaly in South China from the southwest side of Western Pacific subtropical high and the significant convergence of water vapor are responsible for the positive rainfall anomalies in the Yangtze river basin and northern China.Meanwhile,the western North Pacific anomalous anticyclone covers the southeastern periphery of China so that the rainfall there becomes less,and vice versa.(4)The results of numerical simulation are basically consistent with observational analysis,the NCAR CAM5 model simulates the anomalous anticyclone over western North Pacific successfully,through which the Atlantic Ni?o in summer can influence summer precipitation anomaly in China.