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ORIGINAL RESEARCH article
Front. Mar. Sci.
Sec. Physical Oceanography
Volume 12 - 2025 | doi: 10.3389/fmars.2025.1565878
The interdecadal Variation in the Relationship of ENSO with IOD's eastern pole and western pole around 2000
Provisionally accepted- College of Ocean and Meteorology/South China Sea Institute of Marine and Meteorology, Guangdong Ocean University, Zhanjiang, Guangdong Province, China
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The El Niño-Southern Oscillation (ENSO) and Indian Ocean Dipole (IOD) coupling exhibits important globe climate impacts. The relationship of ENSO with IOD's eastern pole (EP) and western pole (WP) and its interdecadal variation have not been determined. Based on observations and reanalysis datasets, this study reveals that the ENSO and IOD-EP relationship significantly weakened, while the ENSO and IOD-WP relationship strengthened after 2000.Changes in ENSO-IOD-EP connection outweighs that in ENSO-IOD-WP connection. The El Niño-positive IOD (pIOD) coupling weakened and the La Niña-negative IOD (nIOD) coupling strengthened. In addition, the changes in El Niño-pIOD coupling dominates. From atmospheric view, anomalous ascending branch of Walker circulation in the Maritime Continent intensified after 2000. New status of Walker circulation favored weakened wind easterlies and SST warming in IOD-EP, which hindered the development of pIOD events but promoted the development of nIOD events. From oceanic wave process view, the equatorial and extra-equatorial downwelling Rossby waves both favored SST warming in IOD-WP after 2000, which promoted the generation of pIOD events but hindered the generation of nIOD events. Using information flow, causal analysis verifies that the influence of atmospheric processes on IOD-EP decreased and the influence of oceanic wave processes on IOD-WP increased. Such weakened ENSO-IOD-EP connection can be attributed to the weakened wind easterlies in pIOD events associated with La Niña-like condition in Pacific and declined Bjerknes feedback induced by the deepened thermocline condition in IOD-EP. While the strengthened ENSO-IOD-WP connection can be attributed to the strengthened downwelling Rossby waves in pIOD events, which were related to IO Basin (IOB) warming induced by El Niño in previous year. I.e, increased consecutive El Niños associated with La Niña-like condition are favorable for enhanced ENSO-pIOD-WP connection. Under the background of ENSO properties transition occurring around 2000, our research will contribute to a better understanding on the ENSO-IOD coupling and its implications.
Keywords: Enso, IOD's eastern pole (EP) and western pole (WP), asymmetry in interdecadal variation, regulation of atmospheric processes on IOD-EP, regulation of oceanic wave processes on IOD-WP, Oceanic Rossby waves, Causal analysis, mean-state
Received: 23 Jan 2025; Accepted: 16 Apr 2025.
Copyright: © 2025 Huang, Yan, XU and Zheng. This is an open-access article distributed under the terms of the Creative Commons Attribution License (CC BY). The use, distribution or reproduction in other forums is permitted, provided the original author(s) or licensor are credited and that the original publication in this journal is cited, in accordance with accepted academic practice. No use, distribution or reproduction is permitted which does not comply with these terms.
* Correspondence: Li Yan, College of Ocean and Meteorology/South China Sea Institute of Marine and Meteorology, Guangdong Ocean University, Zhanjiang, Guangdong Province, China
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