Disentangling the North Pacific Meridional Mode from tropical Pacific variability
Abstract Variations of sea-surface temperature (SST) in the subtropical North Pacific have received considerable attention due to their potential role as a precursor of El Niño-Southern Oscillation (ENSO) events in the tropical Pacific as well as their role in regional climate impacts. These subtrop...
| Main Authors: | , , , |
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| Format: | Article |
| Language: | English |
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Nature Portfolio
2022-11-01
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| Series: | npj Climate and Atmospheric Science |
| Online Access: | https://doi.org/10.1038/s41612-022-00317-8 |
| _version_ | 1811217159554072576 |
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| author | Ingo Richter Malte F. Stuecker Naoya Takahashi Niklas Schneider |
| author_facet | Ingo Richter Malte F. Stuecker Naoya Takahashi Niklas Schneider |
| author_sort | Ingo Richter |
| collection | DOAJ |
| description | Abstract Variations of sea-surface temperature (SST) in the subtropical North Pacific have received considerable attention due to their potential role as a precursor of El Niño-Southern Oscillation (ENSO) events in the tropical Pacific as well as their role in regional climate impacts. These subtropical SST variations, known as the North Pacific Meridional Mode (PMM), are thought to be triggered by extratropical atmospheric forcing and amplified by air-sea coupling involving surface winds, evaporation, and SST. The PMM is often defined through a statistical technique called maximum covariance analysis (MCA) that identifies patterns of maximum covariability between SST and surface winds. Here we show that SST alone is sufficient to reproduce the MCA-based PMM index with near-perfect correlation. This dominance of the SST suggests that the MCA-based definition of the PMM may not be ideally suited for capturing two-way wind-SST interaction or, alternatively, that this interaction is relatively weak. We further show that the MCA-based PMM definition conflates intrinsic subtropical and remote ENSO variability, thereby undermining its interpretation as an ENSO precursor. Our findings indicate that, while air-sea coupling may be important for variability in the subtropical North Pacific, it cannot be reliably identified by the MCA-based definition of the PMM. This highlights the need for refined tools to diagnose variability in the subtropical North Pacific. |
| first_indexed | 2024-04-12T06:49:15Z |
| format | Article |
| id | doaj.art-96487a756ff94780858e8177aa31c049 |
| institution | Directory Open Access Journal |
| issn | 2397-3722 |
| language | English |
| last_indexed | 2024-04-12T06:49:15Z |
| publishDate | 2022-11-01 |
| publisher | Nature Portfolio |
| record_format | Article |
| series | npj Climate and Atmospheric Science |
| spelling | doaj.art-96487a756ff94780858e8177aa31c0492022-12-22T03:43:25ZengNature Portfolionpj Climate and Atmospheric Science2397-37222022-11-01511910.1038/s41612-022-00317-8Disentangling the North Pacific Meridional Mode from tropical Pacific variabilityIngo Richter0Malte F. Stuecker1Naoya Takahashi2Niklas Schneider3Application Laboratory, Research Institute for Value-Added-Information Generation, Japan Agency for Marine-Earth Science and TechnologyDepartment of Oceanography, School of Ocean and Earth Science and Technology, University of Hawaiʻi at MānoaInternational Pacific Research Center, School of Ocean and Earth Science and Technology, University of Hawaiʻi at MānoaDepartment of Oceanography, School of Ocean and Earth Science and Technology, University of Hawaiʻi at MānoaAbstract Variations of sea-surface temperature (SST) in the subtropical North Pacific have received considerable attention due to their potential role as a precursor of El Niño-Southern Oscillation (ENSO) events in the tropical Pacific as well as their role in regional climate impacts. These subtropical SST variations, known as the North Pacific Meridional Mode (PMM), are thought to be triggered by extratropical atmospheric forcing and amplified by air-sea coupling involving surface winds, evaporation, and SST. The PMM is often defined through a statistical technique called maximum covariance analysis (MCA) that identifies patterns of maximum covariability between SST and surface winds. Here we show that SST alone is sufficient to reproduce the MCA-based PMM index with near-perfect correlation. This dominance of the SST suggests that the MCA-based definition of the PMM may not be ideally suited for capturing two-way wind-SST interaction or, alternatively, that this interaction is relatively weak. We further show that the MCA-based PMM definition conflates intrinsic subtropical and remote ENSO variability, thereby undermining its interpretation as an ENSO precursor. Our findings indicate that, while air-sea coupling may be important for variability in the subtropical North Pacific, it cannot be reliably identified by the MCA-based definition of the PMM. This highlights the need for refined tools to diagnose variability in the subtropical North Pacific.https://doi.org/10.1038/s41612-022-00317-8 |
| spellingShingle | Ingo Richter Malte F. Stuecker Naoya Takahashi Niklas Schneider Disentangling the North Pacific Meridional Mode from tropical Pacific variability npj Climate and Atmospheric Science |
| title | Disentangling the North Pacific Meridional Mode from tropical Pacific variability |
| title_full | Disentangling the North Pacific Meridional Mode from tropical Pacific variability |
| title_fullStr | Disentangling the North Pacific Meridional Mode from tropical Pacific variability |
| title_full_unstemmed | Disentangling the North Pacific Meridional Mode from tropical Pacific variability |
| title_short | Disentangling the North Pacific Meridional Mode from tropical Pacific variability |
| title_sort | disentangling the north pacific meridional mode from tropical pacific variability |
| url | https://doi.org/10.1038/s41612-022-00317-8 |
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