Meridional movement of wind anomalies during ENSO events and their role in event termination

Shayne McGregor, Nandini Ramesh, J Paul Spence, Matthew Heathcote England, Michael James McPhaden, Agus Santoso

Research output: Contribution to journalArticleResearchpeer-review

58 Citations (Scopus)

Abstract

Observational analysis has shown that when El Nino-Southern Oscillation (ENSO) events typically reach their peak amplitude in boreal winter, the associated zonal wind anomalies abruptly shift southward so that the maximum anomalous zonal wind is located around 5-7 S. Here, an analysis utilizing multiple wind products identifies a clear ENSO phase nonlinearity in the extent of this meridional wind movement and its dynamically linked changes in equatorial heat content. It is shown that the meridional wind movement and its discharging effect increase with increasing El Nino amplitude, while both remain relatively small regardless of La Nina amplitude. This result implies that asymmetries in the extent of the meridional wind shift may contribute to the observed asymmetry in the duration of El Nino and La Nina events. We also evaluate the result sensitivities to wind product selection and discuss Eastern Pacific (EP) and Central Pacific (CP) El Nino event differences. Key Points The meridional shift plays a prominent role in strong El Nino event termination The magnitude of this meridional shift is related to El Nino event intensity ENSO phase asymmetries in the wind shift play a role in the duration asymmetry (c)2013. American Geophysical Union. All Rights Reserved.
Original languageEnglish
Pages (from-to)749 - 754
Number of pages6
JournalGeophysical Research Letters
Volume40
Issue number4
DOIs
Publication statusPublished - 2013
Externally publishedYes

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