ENSO and West Pacific Seasonality Driven by the South Asian Monsoon

Abstract The equatorial Pacific exhibits a clear seasonal cycle, with West Pacific SSTs being highest during boreal autumn and El Niño/Southern Oscillation (ENSO) events tending to peak during boreal winter. In this work, we use the concept of a monsoonal mode and idealized coupled simulations to sh...

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Main Authors: P. J. Tuckman, Jane E. Smyth, Jingyuan Li, Nicholas J. Lutsko, John Marshall
Format: Article
Language:English
Published: Wiley 2025-05-01
Series:Geophysical Research Letters
Subjects:
Online Access:https://doi.org/10.1029/2024GL111084
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author P. J. Tuckman
Jane E. Smyth
Jingyuan Li
Nicholas J. Lutsko
John Marshall
author_facet P. J. Tuckman
Jane E. Smyth
Jingyuan Li
Nicholas J. Lutsko
John Marshall
author_sort P. J. Tuckman
collection DOAJ
description Abstract The equatorial Pacific exhibits a clear seasonal cycle, with West Pacific SSTs being highest during boreal autumn and El Niño/Southern Oscillation (ENSO) events tending to peak during boreal winter. In this work, we use the concept of a monsoonal mode and idealized coupled simulations to show that the presence of a large land mass in the Northern Hemisphere can lead to these seasonal asymmetries. Specifically, warm air moving east from the Asian summer monsoon suppresses surface fluxes in the West Pacific, leading to increased temperature there during the following months. The warmth of the West Pacific in boreal autumn strengthens the Walker circulation and the zonal temperature gradient across the Pacific, leading to the growth of El Niño events during that season. In summary, the presence of the Asian monsoon north of the equator results in ENSO events preferentially growing during boreal autumn and peaking during boreal winter.
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id doaj-art-44d61c9b1daf4bd68e2099f7c8181ea3
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series Geophysical Research Letters
spelling doaj-art-44d61c9b1daf4bd68e2099f7c8181ea32025-08-20T03:12:52ZengWileyGeophysical Research Letters0094-82761944-80072025-05-01529n/an/a10.1029/2024GL111084ENSO and West Pacific Seasonality Driven by the South Asian MonsoonP. J. Tuckman0Jane E. Smyth1Jingyuan Li2Nicholas J. Lutsko3John Marshall4Department of Earth, Atmospheric, and Planetary Sciences Massachusetts Institute of Technology Cambridge MA USADepartment of Earth, Atmospheric, and Planetary Sciences Massachusetts Institute of Technology Cambridge MA USAScripps Institution of Oceanography University of California San Diego La Jolla CA USAScripps Institution of Oceanography University of California San Diego La Jolla CA USADepartment of Earth, Atmospheric, and Planetary Sciences Massachusetts Institute of Technology Cambridge MA USAAbstract The equatorial Pacific exhibits a clear seasonal cycle, with West Pacific SSTs being highest during boreal autumn and El Niño/Southern Oscillation (ENSO) events tending to peak during boreal winter. In this work, we use the concept of a monsoonal mode and idealized coupled simulations to show that the presence of a large land mass in the Northern Hemisphere can lead to these seasonal asymmetries. Specifically, warm air moving east from the Asian summer monsoon suppresses surface fluxes in the West Pacific, leading to increased temperature there during the following months. The warmth of the West Pacific in boreal autumn strengthens the Walker circulation and the zonal temperature gradient across the Pacific, leading to the growth of El Niño events during that season. In summary, the presence of the Asian monsoon north of the equator results in ENSO events preferentially growing during boreal autumn and peaking during boreal winter.https://doi.org/10.1029/2024GL111084ENSOmonsoonseasonalityWest Pacific
spellingShingle P. J. Tuckman
Jane E. Smyth
Jingyuan Li
Nicholas J. Lutsko
John Marshall
ENSO and West Pacific Seasonality Driven by the South Asian Monsoon
Geophysical Research Letters
ENSO
monsoon
seasonality
West Pacific
title ENSO and West Pacific Seasonality Driven by the South Asian Monsoon
title_full ENSO and West Pacific Seasonality Driven by the South Asian Monsoon
title_fullStr ENSO and West Pacific Seasonality Driven by the South Asian Monsoon
title_full_unstemmed ENSO and West Pacific Seasonality Driven by the South Asian Monsoon
title_short ENSO and West Pacific Seasonality Driven by the South Asian Monsoon
title_sort enso and west pacific seasonality driven by the south asian monsoon
topic ENSO
monsoon
seasonality
West Pacific
url https://doi.org/10.1029/2024GL111084
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AT jingyuanli ensoandwestpacificseasonalitydrivenbythesouthasianmonsoon
AT nicholasjlutsko ensoandwestpacificseasonalitydrivenbythesouthasianmonsoon
AT johnmarshall ensoandwestpacificseasonalitydrivenbythesouthasianmonsoon