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FENG Junqiao, WANG Fujun, WANG Qingye, HU Dunxin. Intraseasonal variability of the equatorial Pacific Ocean and its relationship with ENSO based on Self-Organizing Maps analysis[J]. Journal of Oceanology and Limnology, 2020, 38(4): 1108-1122

Intraseasonal variability of the equatorial Pacific Ocean and its relationship with ENSO based on Self-Organizing Maps analysis

FENG Junqiao1,2,3,4, WANG Fujun1,2,3,4, WANG Qingye1,2,3,4, HU Dunxin1,2,3,4
1 Institute of Oceanology, Chinese Academy of Sciences, Qingdao 266071, China;
2 Key Laboratory of Ocean Circulation and Waves, Chinese Academy of Sciences, Qingdao 266071, China;
3 Center for Ocean Mega-Science, Chinese Academy of Sciences, Qingdao 266071, China;
4 Function Laboratory for Ocean Dynamics and Climate, Qingdao National Laboratory for Marine Science and Technology, Qingdao 266237, China
We investigated the intraseasonal variability of equatorial Pacific subsurface temperature and its relationship with El Niño-Southern Oscillation (ENSO) using Self-Organizing Maps (SOM) analysis. Variation in intraseasonal subsurface temperature is mainly found along the thermocline. The SOM patterns concentrate in basin-wide seesaw or sandwich structures along an east-west axis. Both the seesaw and sandwich SOM patterns oscillate with periods of 55 to 90 days, with the sequence of them showing features of equatorial intraseasonal Kelvin wave, and have marked interannual variations in their occurrence frequencies. Further examination shows that the interannual variability of the SOM patterns is closely related to ENSO; and maxima in composite interannual variability of the SOM patterns are located in the central Pacific during CP El Niño and in the eastern Pacific during EP El Niño. These results imply that some of the ENSO forcing is manifested through changes in the occurrence frequency of intraseasonal patterns, in which the change of the intraseasonal Kelvin wave plays an important role.
Key words:    intraseasonal variability|equatorial Pacific|El Ni�o-Southern Oscillation (ENSO)|SelfOrganizing Maps (SOM)   
Received: 2019-12-19   Revised: 2020-01-26
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