Weakening of the El Niño amplitude since the late 1990s and its link to decadal change in the North Pacific climate
The amplitude of El Niño, measured by the Nino3.4 sea surface temperature anomaly (SSTA) index, has exhibited an interdecadal change with a weakening trend since the late 1990s, characterized by the distinct Bjerknes stability index between 1980–1998 and 1999–2014. Statistical results suggest that t...
Published in: | International Journal of Climatology |
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crwiley:10.1002/joc.6063 2024-06-23T07:45:14+00:00 Weakening of the El Niño amplitude since the late 1990s and its link to decadal change in the North Pacific climate Xu, Kang Wang, Weiqiang Liu, Boqi Zhu, Congwen National Natural Science Foundation of China 2019 http://dx.doi.org/10.1002/joc.6063 https://api.wiley.com/onlinelibrary/tdm/v1/articles/10.1002%2Fjoc.6063 https://onlinelibrary.wiley.com/doi/pdf/10.1002/joc.6063 https://onlinelibrary.wiley.com/doi/full-xml/10.1002/joc.6063 https://rmets.onlinelibrary.wiley.com/doi/pdf/10.1002/joc.6063 en eng Wiley http://onlinelibrary.wiley.com/termsAndConditions#vor International Journal of Climatology volume 39, issue 10, page 4125-4138 ISSN 0899-8418 1097-0088 journal-article 2019 crwiley https://doi.org/10.1002/joc.6063 2024-06-04T06:44:30Z The amplitude of El Niño, measured by the Nino3.4 sea surface temperature anomaly (SSTA) index, has exhibited an interdecadal change with a weakening trend since the late 1990s, characterized by the distinct Bjerknes stability index between 1980–1998 and 1999–2014. Statistical results suggest that this was primarily induced by the attenuation of the zonal wind stress and low‐level wind anomalies in response to the zonal equatorial SSTA gradient. The weakened atmospheric responses to the zonal equatorial SSTA gradient were associated with the obvious westward extension of the negative sea level pressure anomalies (SLPA) over the tropics. This was mainly attributed to the transition of the dominant atmospheric circulation over the North Pacific, where the Aleutian Low (AL) mode was replaced by the North Pacific Oscillation (NPO) mode after the late 1990s. Numerical experiments from the long‐term historical simulations of the GFDL‐CM3 model indicate that both of the AL and NPO were dominant over the North Pacific and alternated on the interdecadal time‐scale. When the NPO mode was dominant, it became more effective at playing a role in triggering an El Niño in the central Pacific via the seasonal footprinting mechanism over the subtropical northeastern Pacific. Such a change might cause the westward shift of the tropical SLPA and the attenuated atmospheric responses to the zonal SSTA gradient, ultimately resulting in the weakening of the El Niño amplitude. Article in Journal/Newspaper aleutian low Wiley Online Library Pacific International Journal of Climatology 39 10 4125 4138 |
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Wiley Online Library |
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English |
description |
The amplitude of El Niño, measured by the Nino3.4 sea surface temperature anomaly (SSTA) index, has exhibited an interdecadal change with a weakening trend since the late 1990s, characterized by the distinct Bjerknes stability index between 1980–1998 and 1999–2014. Statistical results suggest that this was primarily induced by the attenuation of the zonal wind stress and low‐level wind anomalies in response to the zonal equatorial SSTA gradient. The weakened atmospheric responses to the zonal equatorial SSTA gradient were associated with the obvious westward extension of the negative sea level pressure anomalies (SLPA) over the tropics. This was mainly attributed to the transition of the dominant atmospheric circulation over the North Pacific, where the Aleutian Low (AL) mode was replaced by the North Pacific Oscillation (NPO) mode after the late 1990s. Numerical experiments from the long‐term historical simulations of the GFDL‐CM3 model indicate that both of the AL and NPO were dominant over the North Pacific and alternated on the interdecadal time‐scale. When the NPO mode was dominant, it became more effective at playing a role in triggering an El Niño in the central Pacific via the seasonal footprinting mechanism over the subtropical northeastern Pacific. Such a change might cause the westward shift of the tropical SLPA and the attenuated atmospheric responses to the zonal SSTA gradient, ultimately resulting in the weakening of the El Niño amplitude. |
author2 |
National Natural Science Foundation of China |
format |
Article in Journal/Newspaper |
author |
Xu, Kang Wang, Weiqiang Liu, Boqi Zhu, Congwen |
spellingShingle |
Xu, Kang Wang, Weiqiang Liu, Boqi Zhu, Congwen Weakening of the El Niño amplitude since the late 1990s and its link to decadal change in the North Pacific climate |
author_facet |
Xu, Kang Wang, Weiqiang Liu, Boqi Zhu, Congwen |
author_sort |
Xu, Kang |
title |
Weakening of the El Niño amplitude since the late 1990s and its link to decadal change in the North Pacific climate |
title_short |
Weakening of the El Niño amplitude since the late 1990s and its link to decadal change in the North Pacific climate |
title_full |
Weakening of the El Niño amplitude since the late 1990s and its link to decadal change in the North Pacific climate |
title_fullStr |
Weakening of the El Niño amplitude since the late 1990s and its link to decadal change in the North Pacific climate |
title_full_unstemmed |
Weakening of the El Niño amplitude since the late 1990s and its link to decadal change in the North Pacific climate |
title_sort |
weakening of the el niño amplitude since the late 1990s and its link to decadal change in the north pacific climate |
publisher |
Wiley |
publishDate |
2019 |
url |
http://dx.doi.org/10.1002/joc.6063 https://api.wiley.com/onlinelibrary/tdm/v1/articles/10.1002%2Fjoc.6063 https://onlinelibrary.wiley.com/doi/pdf/10.1002/joc.6063 https://onlinelibrary.wiley.com/doi/full-xml/10.1002/joc.6063 https://rmets.onlinelibrary.wiley.com/doi/pdf/10.1002/joc.6063 |
geographic |
Pacific |
geographic_facet |
Pacific |
genre |
aleutian low |
genre_facet |
aleutian low |
op_source |
International Journal of Climatology volume 39, issue 10, page 4125-4138 ISSN 0899-8418 1097-0088 |
op_rights |
http://onlinelibrary.wiley.com/termsAndConditions#vor |
op_doi |
https://doi.org/10.1002/joc.6063 |
container_title |
International Journal of Climatology |
container_volume |
39 |
container_issue |
10 |
container_start_page |
4125 |
op_container_end_page |
4138 |
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1802638481074159616 |