Abstract
The tropical Pacific experienced a sustained warm sea surface condition that started in 2014 and a very strong El Niño event in 2015. One striking feature of this event was the horseshoe-like pattern of positive subsurface thermal anomalies that was sustained in the western-central equatorial Pacific throughout 2014–2015. Observational data and an intermediate ocean model are used to describe the sea surface temperature (SST) evolution during 2014–2015. Emphasis is placed on the processes involved in the 2015 El Niño event and their relationships with SST anomalies, including remote effects associated with the propagation and reflection of oceanic equatorial waves (as indicated in sea level (SL) signals) at the boundaries and local effects of the positive subsurface thermal anomalies. It is demonstrated that the positive subsurface thermal anomaly pattern that was sustained throughout 2014–2015 played an important role in maintaining warm SST anomalies in the equatorial Pacific. Further analyses of the SST budget revealed the dominant processes contributing to SST anomalies during 2014–2015. These analyses provide an improved understanding of the extent to which processes associated with the 2015 El Niño event are consistent with current El Niño and Southern Oscillation theories.
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Acknowledgements
We would like to thank Profs. Mu Mu and Dunxin Hu for their comment. The authors wish to thank the two anonymous reviewers for their comments. This research was supported by the National Natural Science Foundation of China (Grant Nos. 41690122, 41690120, 41490644, 41490640 & 41475101), AoShan Talents Program Supported by Qingdao National Laboratory for Marine Science and Technology (Grant No. 2015ASTP), the Chinese Academy of Sciences Strategic Priority Project, the Western Pacific Ocean System (Grant Nos. XDA11010105 & XDA11020306), the National Natural Science Foundation of China-Shandong Joint Fund for Marine Science Research Centers (Grant No. U1406401), and the National Natural Science Foundation of China Innovative Group Grant (Grant No. 41421005), Taishan Scholarship and Qingdao Innovative Program (Grant No. 2014GJJS0101), China Postdoctoral Science Foundation and Qingdao Postdoctoral Application Research Project.
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Zhang, R., Gao, C. Processes involved in the second-year warming of the 2015 El Niño event as derived from an intermediate ocean model. Sci. China Earth Sci. 60, 1601–1613 (2017). https://doi.org/10.1007/s11430-016-0201-9
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DOI: https://doi.org/10.1007/s11430-016-0201-9