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Revisiting Asymmetry for the Decaying Phases of El Niño and La Niña |
CHEN Wei1, LU Ri-Yu1, Buwen Dong2 |
1State Key Laboratory of Numerical Modeling for Atmospheric Sciences and Geophysical Fluid Dynamics, Institute of Atmospheric Physics, Chinese Academy of Sciences, Beijing 100029, China
2National Centre for Atmospheric Science-Climate, Department of Meteorology, University of Reading, Reading, UK |
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Abstract This study investigated the relationship between the asymmetry in the duration of El Ni?o and La Ni?a and the length of their decaying phases. The results suggested that the duration asymmetry comes from the long decaying ENSO cases rather than the short decaying ones. The evolutions of short decaying El Ni?o and La Ni?a are approximately a mirror image with a rapid decline in the following summer for the warm and cold events. However, a robust asymmetry was found in long decaying cases, with a prolonged and re-intensified La Ni?a in the following winter. The asymmetry for long decaying cases starts from the westward extension of the zonal wind anomalies in a mature winter, and is further contributed to by the air-sea interaction over the tropical Pacific in the following seasons.
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Received: 20 November 2013
Revised: 17 December 2013
Accepted: 23 December 2014
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Corresponding Author:
CHEN Wei
E-mail: chenwei@mail.iap.ac.cn
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