Impact of El Niño on atmospheric circulations over East Asia and rainfall in China: Role of the anomalous western North Pacific anticyclone

• Published in: Science China. Earth sciences Vol. 60; no. 6; pp. 1124 - 1132
• Main Authors: Zhang, RenHe, Min, QingYe, Su, JingZhi
• Format: Journal Article
• Language: English
• Published: Beijing Science China Press 01.06.2017; Springer Nature B.V
• Subjects: Air-sea interaction; Annual variations; Anomalies; Anticyclones; Asymmetry; Cooling; Earth and Environmental Science; Earth Sciences; El Nino; La Nina; Ocean currents; Ocean temperature; Planetary waves; Progress; Rain; Rainfall; Reviews; Sea surface; Sea surface temperature; Summer; Surface temperature; Temperature; Temperature anomalies; Temperature effects; Tropical climate; Variability; Winter; East Asia; China; Anomalous western North Pacific anticyclone; Rainfall in China; El Niño; Atmospheric circulations over East Asia
• ISSN: 1674-7313; 1869-1897
• DOI: 10.1007/s11430-016-9026-x

This paper presents a review on the impact of El Niño on the interannual variability of atmospheric circulations over East Asia and rainfall in China through the anomalous anticyclone over western North Pacific (WNPAC). It explains the formation mechanisms of the WNPAC and physical processes by which the WNPAC affects the rainfall in China. During the mature phase of El Niño, the convective cooling anomalies over western tropical Pacific caused by the weakened convections trigger up an atmospheric Rossby wave response, resulting in the generation of the WNPAC. The WNPAC can persist from the winter when the El Niño is in its peak to subsequent summer, which is maintained by multiple factors including the sustained presence of convective cooling anomalies and the local air-sea interaction over western tropical Pacific, and the persistence of sea surface temperature anomalies (SSTA) in tropical Indian and tropical North Atlantic. The WNPAC can influence the atmospheric circulations over East Asia and rainfall in China not only simultaneously, but also in the subsequent summer after an El Niño year, leading to more rainfall over southern China. The current paper also points out that significant anomalies of atmospheric circulations over East Asia and rainfall over southern China occur in El Niño winter but not in La Niña winter, suggesting that El Niño and La Niña have an asymmetric effect. Other issues, including the impact of El Niño diversity and its impact as well as the relations of the factors affecting the persistence of the WNPAC with summer rainfall anomalies in China, are also discussed. At the end of this paper some issues calling for further investigation are discussed.