Dominant contribution of atmospheric nonlinearities to ENSO asymmetry and extreme El Niño events
Abstract Extreme El Niño events have outsized impacts and strongly contribute to the El Niño Southern Oscillation (ENSO) warm/cold phase asymmetries. There is currently no consensus on the respective importance of oceanic and atmospheric nonlinearities for those asymmetries. Here, we use atmospheric...
| Main Authors: | , , , , , , |
|---|---|
| Format: | Article |
| Language: | English |
| Published: |
Nature Portfolio
2024-04-01
|
| Series: | Scientific Reports |
| Subjects: | |
| Online Access: | https://doi.org/10.1038/s41598-024-58803-3 |
| _version_ | 1827291555008872448 |
|---|---|
| author | G. Srinivas J. Vialard F. Liu A. Voldoire T. Izumo E. Guilyardi M. Lengaigne |
| author_facet | G. Srinivas J. Vialard F. Liu A. Voldoire T. Izumo E. Guilyardi M. Lengaigne |
| author_sort | G. Srinivas |
| collection | DOAJ |
| description | Abstract Extreme El Niño events have outsized impacts and strongly contribute to the El Niño Southern Oscillation (ENSO) warm/cold phase asymmetries. There is currently no consensus on the respective importance of oceanic and atmospheric nonlinearities for those asymmetries. Here, we use atmospheric and oceanic general circulation models that reproduce ENSO asymmetries well to quantify the atmospheric nonlinearities contribution. The linear and nonlinear components of the wind stress response to Sea Surface Temperature (SST) anomalies are isolated using ensemble atmospheric experiments, and used to force oceanic experiments. The wind stress-SST nonlinearity is dominated by the deep atmospheric convective response to SST. This wind-stress nonlinearity contributes to ~ 40% of the peak amplitude of extreme El Niño events and ~ 55% of the prolonged eastern Pacific warming they generate until the following summer. This large contribution arises because nonlinearities consistently drive equatorial westerly anomalies, while the larger linear component is made less efficient by easterly anomalies in the western Pacific during fall and winter. Overall, wind-stress nonlinearities fully account for the eastern Pacific positive ENSO skewness. Our findings underscore the pivotal role of atmospheric nonlinearities in shaping extreme El Niño events and, more generally, ENSO asymmetry. |
| first_indexed | 2024-04-24T12:40:02Z |
| format | Article |
| id | doaj.art-018eb4d8377b4f91adda7a163a77b0c8 |
| institution | Directory Open Access Journal |
| issn | 2045-2322 |
| language | English |
| last_indexed | 2024-04-24T12:40:02Z |
| publishDate | 2024-04-01 |
| publisher | Nature Portfolio |
| record_format | Article |
| series | Scientific Reports |
| spelling | doaj.art-018eb4d8377b4f91adda7a163a77b0c82024-04-07T11:17:03ZengNature PortfolioScientific Reports2045-23222024-04-0114111210.1038/s41598-024-58803-3Dominant contribution of atmospheric nonlinearities to ENSO asymmetry and extreme El Niño eventsG. Srinivas0J. Vialard1F. Liu2A. Voldoire3T. Izumo4E. Guilyardi5M. Lengaigne6CSIR-National Institute of OceanographyLOCEAN-IPSL, Sorbonne Université -CNRS-IRD-MNHNLOCEAN-IPSL, Sorbonne Université -CNRS-IRD-MNHNCNRM, CNRS, Météo‐France, Université de ToulouseIRD, UMR241 (IRD-UPF-ILM-Ifremer)LOCEAN-IPSL, Sorbonne Université -CNRS-IRD-MNHNMARBEC, CNRS, IFREMER, IRD, University of MontpellierAbstract Extreme El Niño events have outsized impacts and strongly contribute to the El Niño Southern Oscillation (ENSO) warm/cold phase asymmetries. There is currently no consensus on the respective importance of oceanic and atmospheric nonlinearities for those asymmetries. Here, we use atmospheric and oceanic general circulation models that reproduce ENSO asymmetries well to quantify the atmospheric nonlinearities contribution. The linear and nonlinear components of the wind stress response to Sea Surface Temperature (SST) anomalies are isolated using ensemble atmospheric experiments, and used to force oceanic experiments. The wind stress-SST nonlinearity is dominated by the deep atmospheric convective response to SST. This wind-stress nonlinearity contributes to ~ 40% of the peak amplitude of extreme El Niño events and ~ 55% of the prolonged eastern Pacific warming they generate until the following summer. This large contribution arises because nonlinearities consistently drive equatorial westerly anomalies, while the larger linear component is made less efficient by easterly anomalies in the western Pacific during fall and winter. Overall, wind-stress nonlinearities fully account for the eastern Pacific positive ENSO skewness. Our findings underscore the pivotal role of atmospheric nonlinearities in shaping extreme El Niño events and, more generally, ENSO asymmetry.https://doi.org/10.1038/s41598-024-58803-3El NiñoLa NiñaSSTRainfallWind stressAtmospheric nonlinearities |
| spellingShingle | G. Srinivas J. Vialard F. Liu A. Voldoire T. Izumo E. Guilyardi M. Lengaigne Dominant contribution of atmospheric nonlinearities to ENSO asymmetry and extreme El Niño events Scientific Reports El Niño La Niña SST Rainfall Wind stress Atmospheric nonlinearities |
| title | Dominant contribution of atmospheric nonlinearities to ENSO asymmetry and extreme El Niño events |
| title_full | Dominant contribution of atmospheric nonlinearities to ENSO asymmetry and extreme El Niño events |
| title_fullStr | Dominant contribution of atmospheric nonlinearities to ENSO asymmetry and extreme El Niño events |
| title_full_unstemmed | Dominant contribution of atmospheric nonlinearities to ENSO asymmetry and extreme El Niño events |
| title_short | Dominant contribution of atmospheric nonlinearities to ENSO asymmetry and extreme El Niño events |
| title_sort | dominant contribution of atmospheric nonlinearities to enso asymmetry and extreme el nino events |
| topic | El Niño La Niña SST Rainfall Wind stress Atmospheric nonlinearities |
| url | https://doi.org/10.1038/s41598-024-58803-3 |
| work_keys_str_mv | AT gsrinivas dominantcontributionofatmosphericnonlinearitiestoensoasymmetryandextremeelninoevents AT jvialard dominantcontributionofatmosphericnonlinearitiestoensoasymmetryandextremeelninoevents AT fliu dominantcontributionofatmosphericnonlinearitiestoensoasymmetryandextremeelninoevents AT avoldoire dominantcontributionofatmosphericnonlinearitiestoensoasymmetryandextremeelninoevents AT tizumo dominantcontributionofatmosphericnonlinearitiestoensoasymmetryandextremeelninoevents AT eguilyardi dominantcontributionofatmosphericnonlinearitiestoensoasymmetryandextremeelninoevents AT mlengaigne dominantcontributionofatmosphericnonlinearitiestoensoasymmetryandextremeelninoevents |