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While the prominent influence of El Niño‐Southern Oscillation (ENSO) on the Indian Ocean Oscillation (IOD) is widely recognized, intricate relationships between them are often invoked that introduce challenges into seasonal predictions. Previous studies have shown that different flavors of El Niño exhibit distinct associations with the IOD. In this study, we demonstrate that La Niña's teleconnection to the IOD is primarily controlled by its longitudinal position. Westward‐displaced La Niña events tend to produce stronger negative convection anomalies in the central Pacific and more pronounced Walk Circulation anomalies, thereby triggering strong negative IOD events. In contrast, eastward‐displaced La Niña events are usually accompanied by feeble convection response due to the excessively cold conditions in the cold tongue, yielding insignificant IOD response. The pivotal role of La Niña's longitudinal position on the IOD's response is realistically reproduced by targeted pacemaker experiments, providing new insights into inter‐basin climate connections.
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A Positive Indian Ocean Dipole Leads to an Indian Ocean Basin Mode that Favors the Development of La Niña the Following Year
Abstract Interactions among the El Niño‐Southern Oscillation, Indian Ocean Basin mode (IOB), and Indian Ocean Dipole (IOD) significantly impact global climate variability and seasonal predictions. Traditionally, positive IOD (pIOD) and IOB warming events are associated with El Niño, driven by its influence on the tropical Indian Ocean through Walker Circulation anomalies. Our findings enrich this framework, revealing that a pIOD without El Niño can independently trigger IOB warming, and both types of pIODs can induce La Niña events. While El Niño primarily forces IOB warming and subsequent La Niña development via the atmospheric bridge across the Maritime Continent, pIODs independent of El Niño influence IOB warming through oceanic dynamics, which further favors La Niña development in the following year. The NMEFC‐CESM model sensitivity experiments underscore the critical role of thermocline processes in this mechanism, dependent on the pIOD's temperature amplitude, offering vital insights for forecasting post‐IOD, IOB, and La Niña events.
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- Award ID(s):
- 1851316
- PAR ID:
- 10594182
- Publisher / Repository:
- Wiley
- Date Published:
- Journal Name:
- Geophysical Research Letters
- Volume:
- 52
- Issue:
- 7
- ISSN:
- 0094-8276
- Format(s):
- Medium: X
- Sponsoring Org:
- National Science Foundation
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- Free Publicly Accessible Full Text
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Accepted Manuscript
- Journal Article:
- https://doi.org/10.1029/2024GL112632
