Abstract
The Yangtze river basin, in South East China, experiences anomalously high precipitation in summers following El Niño. This can lead to extensive flooding and loss of life. However, the response following La Niña has not been well documented. In this study, the response of Yangtze summer rainfall to El Niño/La Niña is found to be asymmetric, with no significant response following La Niña. The nature of this asymmetric response is found to be in good agreement with that simulated by the Met Office seasonal forecast system. Yangtze summer rainfall correlates positively with spring sea surface temperatures in the Indian Ocean and northwest Pacific. Indian Ocean sea surface temperatures are found to respond linearly to El Niño/La Niña, and to have a linear impact on Yangtze summer rainfall. However, northwest Pacific sea surface temperatures respond much more strongly following El Niño and, further, correlate more strongly with positive rainfall years. It is concluded that, whilst delayed Indian Ocean signals may influence summer Yangtze rainfall, it is likely that they do not lead to the asymmetric nature of the rainfall response to El Niño/La Niña.
Highlights
In the summer following a winter El Niño event, the Yangtze river basin often experiences greater than average rainfall (Wang et al 2001, Zhang et al 2007, Li et al 2016, Xie et al 2016), sometimes leading to extensive flooding with significant loss of life and economic impact (Zong and Chen 2000, Gong and Ho 2002, Zheng et al 2006).Understanding the mechanisms whereby El Niñ o events can influence Yangtze river rainfall with this long (6 month) lag is the subject of considerable ongoing research
The observed strong positive anomaly in precipitation following El Niño is in good agreement with the Global Seasonal forecast system version 5 (GloSea5) ensemble mean response (Li et al 2016)
Following a winter La Niñ a event, no significant signal is found, in Mean sea level pressure (MSLP), meridional wind or precipitation. This observed asymmetric response is in good agreement with the ensemble mean response simulated by the current Met Office seasonal forecast system, GloSea5
Summary
Steven C Hardiman1,6 , Nick J Dunstone, Adam A Scaife, Philip E Bett , Chaofan Li3, Bo Lu4, Hong-Li Ren, Doug M Smith and Claudia C Stephan. China 4 Laboratory for Climate Studies, National Climate Center, China Meteorological Administration, Beijing, People’s Republic of China 5 Department of Meteorology, University of Reading, Reading, United Kingdom 6 Author to whom any correspondence should be addressed
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Free) 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call
