The teleconnection of extreme El Niño–Southern Oscillation (ENSO) events to the tropical North Atlantic in coupled climate models
<p>El Niño–Southern Oscillation (ENSO) is a major source for teleconnections, including towards the tropical North Atlantic (TNA) region, whereby TNA sea surface temperatures (SSTs) are positively correlated with ENSO in boreal spring following an ENSO event. However, the Pacific–Atlantic conn...
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| Format: | Article |
| Language: | English |
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Copernicus Publications
2023-05-01
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| Series: | Weather and Climate Dynamics |
| Online Access: | https://wcd.copernicus.org/articles/4/471/2023/wcd-4-471-2023.pdf |
| _version_ | 1797822413379993600 |
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| author | J. W. Casselman J. F. Lübbecke T. Bayr W. Huo S. Wahl D. I. V. Domeisen D. I. V. Domeisen |
| author_facet | J. W. Casselman J. F. Lübbecke T. Bayr W. Huo S. Wahl D. I. V. Domeisen D. I. V. Domeisen |
| author_sort | J. W. Casselman |
| collection | DOAJ |
| description | <p>El Niño–Southern Oscillation (ENSO) is a major source for teleconnections, including towards the tropical North Atlantic (TNA) region, whereby TNA sea surface temperatures (SSTs) are positively correlated with ENSO in boreal spring following an ENSO event. However, the Pacific–Atlantic connection can be impacted by different ENSO characteristics, such as the amplitude, location, and timing of Pacific SST anomalies (SSTAs). Indeed, the TNA SSTAs may respond nonlinearly to strong and extreme El Niño events. However, observational data for the number of extreme ENSO events remain limited, restricting our ability to investigate the influence of observed extreme ENSO events. To overcome this issue and to further evaluate the nonlinearity of the TNA SSTA response, two coupled climate models are used, namely the Community Earth System Model version 1 – Whole Atmosphere Community Climate Model (CESM-WACCM) and the Flexible Ocean and Climate Infrastructure version 1 (FOCI). In both models the TNA SSTAs respond linearly to ENSO during extreme El Niño events but nonlinearly to extreme La Niña events for CESM-WACCM. We investigate differences by using indices for all major mechanisms that connect ENSO to the TNA and compare them with reanalysis. CESM-WACCM and FOCI overall represent the teleconnection well, including that the tropical and extratropical pathways are similar to observations. Our results also show that a large portion of the nonlinearity during La Niña is explained by the interaction between Pacific SSTAs and the overlying upper-level divergence.</p> |
| first_indexed | 2024-03-13T10:08:38Z |
| format | Article |
| id | doaj.art-9140e2acb32b440198c26f693a030aeb |
| institution | Directory Open Access Journal |
| issn | 2698-4016 |
| language | English |
| last_indexed | 2024-03-13T10:08:38Z |
| publishDate | 2023-05-01 |
| publisher | Copernicus Publications |
| record_format | Article |
| series | Weather and Climate Dynamics |
| spelling | doaj.art-9140e2acb32b440198c26f693a030aeb2023-05-22T08:49:14ZengCopernicus PublicationsWeather and Climate Dynamics2698-40162023-05-01447148710.5194/wcd-4-471-2023The teleconnection of extreme El Niño–Southern Oscillation (ENSO) events to the tropical North Atlantic in coupled climate modelsJ. W. Casselman0J. F. Lübbecke1T. Bayr2W. Huo3S. Wahl4D. I. V. Domeisen5D. I. V. Domeisen6Institute for Atmospheric and Climate Science, ETH Zurich, Zurich, SwitzerlandGEOMAR Helmholtz Centre for Ocean Research Kiel, Kiel, GermanyGEOMAR Helmholtz Centre for Ocean Research Kiel, Kiel, GermanyGEOMAR Helmholtz Centre for Ocean Research Kiel, Kiel, GermanyGEOMAR Helmholtz Centre for Ocean Research Kiel, Kiel, GermanyInstitute for Atmospheric and Climate Science, ETH Zurich, Zurich, SwitzerlandInstitute of Earth Surface Dynamics, University of Lausanne, Lausanne, Switzerland<p>El Niño–Southern Oscillation (ENSO) is a major source for teleconnections, including towards the tropical North Atlantic (TNA) region, whereby TNA sea surface temperatures (SSTs) are positively correlated with ENSO in boreal spring following an ENSO event. However, the Pacific–Atlantic connection can be impacted by different ENSO characteristics, such as the amplitude, location, and timing of Pacific SST anomalies (SSTAs). Indeed, the TNA SSTAs may respond nonlinearly to strong and extreme El Niño events. However, observational data for the number of extreme ENSO events remain limited, restricting our ability to investigate the influence of observed extreme ENSO events. To overcome this issue and to further evaluate the nonlinearity of the TNA SSTA response, two coupled climate models are used, namely the Community Earth System Model version 1 – Whole Atmosphere Community Climate Model (CESM-WACCM) and the Flexible Ocean and Climate Infrastructure version 1 (FOCI). In both models the TNA SSTAs respond linearly to ENSO during extreme El Niño events but nonlinearly to extreme La Niña events for CESM-WACCM. We investigate differences by using indices for all major mechanisms that connect ENSO to the TNA and compare them with reanalysis. CESM-WACCM and FOCI overall represent the teleconnection well, including that the tropical and extratropical pathways are similar to observations. Our results also show that a large portion of the nonlinearity during La Niña is explained by the interaction between Pacific SSTAs and the overlying upper-level divergence.</p>https://wcd.copernicus.org/articles/4/471/2023/wcd-4-471-2023.pdf |
| spellingShingle | J. W. Casselman J. F. Lübbecke T. Bayr W. Huo S. Wahl D. I. V. Domeisen D. I. V. Domeisen The teleconnection of extreme El Niño–Southern Oscillation (ENSO) events to the tropical North Atlantic in coupled climate models Weather and Climate Dynamics |
| title | The teleconnection of extreme El Niño–Southern Oscillation (ENSO) events to the tropical North Atlantic in coupled climate models |
| title_full | The teleconnection of extreme El Niño–Southern Oscillation (ENSO) events to the tropical North Atlantic in coupled climate models |
| title_fullStr | The teleconnection of extreme El Niño–Southern Oscillation (ENSO) events to the tropical North Atlantic in coupled climate models |
| title_full_unstemmed | The teleconnection of extreme El Niño–Southern Oscillation (ENSO) events to the tropical North Atlantic in coupled climate models |
| title_short | The teleconnection of extreme El Niño–Southern Oscillation (ENSO) events to the tropical North Atlantic in coupled climate models |
| title_sort | teleconnection of extreme el nino southern oscillation enso events to the tropical north atlantic in coupled climate models |
| url | https://wcd.copernicus.org/articles/4/471/2023/wcd-4-471-2023.pdf |
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