Diversity of La Niña onset

Abstract Three La Niña onset types were identified by the K-means cluster analysis of equatorial sea surface temperature anomaly evolutions during the past 111 years (1910–2020). The first type is characterized by a slow basin-wide transition from a neutral year to La Niña, driven by tropical North...

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Main Authors: Xiao Pan, Tim Li
Format: Article
Language:English
Published: Nature Portfolio 2025-07-01
Series:npj Climate and Atmospheric Science
Online Access:https://doi.org/10.1038/s41612-025-01141-6
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author Xiao Pan
Tim Li
author_facet Xiao Pan
Tim Li
author_sort Xiao Pan
collection DOAJ
description Abstract Three La Niña onset types were identified by the K-means cluster analysis of equatorial sea surface temperature anomaly evolutions during the past 111 years (1910–2020). The first type is characterized by a slow basin-wide transition from a neutral year to La Niña, driven by tropical North Atlantic (TNA) warming, which induced anomalous easterlies in the equatorial western Pacific through atmospheric Kelvin wave responses. The easterly anomalies initiate a cooling by triggering upwelling oceanic Kelvin waves, shoaling the thermocline, and strengthening the westward zonal currents. The second and third types are a transition from a central Pacific (CP) and a super eastern Pacific (EP) El Niño to La Niña. The former is attributed to the CP El $${\rm{Ni}}\tilde{{\rm{n}}}{\rm{o}}$$ Ni n ̃ o induced anomalous easterlies in EP that strengthened local surface latent heat flux and anomalous upwelling, whereas the latter is attributed to a substantially shoaling of ocean thermocline associated with the discharge of the preceding super El $${\rm{Ni}}\tilde{{\rm{n}}}{\rm{o}}$$ Ni n ̃ o . These characteristics differentiate diversified types of La Niña onset.
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spelling doaj-art-b8ca87bc520b4f2e9d09503fa0aeae8e2025-08-20T03:45:51ZengNature Portfolionpj Climate and Atmospheric Science2397-37222025-07-018111010.1038/s41612-025-01141-6Diversity of La Niña onsetXiao Pan0Tim Li1Key Laboratory of Physical Oceanography and Frontiers Science Center for Deep Ocean Multispheres and Earth System, College of Oceanic and Atmospheric Sciences, Ocean University of ChinaDepartment of Atmospheric Sciences, School of Ocean and Earth Science and Technology, University of Hawaii at ManoaAbstract Three La Niña onset types were identified by the K-means cluster analysis of equatorial sea surface temperature anomaly evolutions during the past 111 years (1910–2020). The first type is characterized by a slow basin-wide transition from a neutral year to La Niña, driven by tropical North Atlantic (TNA) warming, which induced anomalous easterlies in the equatorial western Pacific through atmospheric Kelvin wave responses. The easterly anomalies initiate a cooling by triggering upwelling oceanic Kelvin waves, shoaling the thermocline, and strengthening the westward zonal currents. The second and third types are a transition from a central Pacific (CP) and a super eastern Pacific (EP) El Niño to La Niña. The former is attributed to the CP El $${\rm{Ni}}\tilde{{\rm{n}}}{\rm{o}}$$ Ni n ̃ o induced anomalous easterlies in EP that strengthened local surface latent heat flux and anomalous upwelling, whereas the latter is attributed to a substantially shoaling of ocean thermocline associated with the discharge of the preceding super El $${\rm{Ni}}\tilde{{\rm{n}}}{\rm{o}}$$ Ni n ̃ o . These characteristics differentiate diversified types of La Niña onset.https://doi.org/10.1038/s41612-025-01141-6
spellingShingle Xiao Pan
Tim Li
Diversity of La Niña onset
npj Climate and Atmospheric Science
title Diversity of La Niña onset
title_full Diversity of La Niña onset
title_fullStr Diversity of La Niña onset
title_full_unstemmed Diversity of La Niña onset
title_short Diversity of La Niña onset
title_sort diversity of la nina onset
url https://doi.org/10.1038/s41612-025-01141-6
work_keys_str_mv AT xiaopan diversityoflaninaonset
AT timli diversityoflaninaonset