Current Climate Change Reports

, Volume 5, Issue 4, pp 296–307 | Cite as

The Pacific Meridional Mode and ENSO: a Review

  • Dillon J. AmayaEmail author
Internal Climate Variability (S-P Xie, Section Editor)
Part of the following topical collections:
  1. Topical Collection on Internal Climate Variability


Purpose of Review

This paper reviews recent progress in understanding of the North Pacific Meridional Mode (NPMM) and its influence on the timing, magnitude, flavor, and intensity of the El Niño-Southern Oscillation (ENSO).

Recent Findings

The NPMM is a seasonally evolving mode of coupled climate variability and features several distinct opportunities to influence ENSO. They include: (1) A Wind-Evaporation-SST (WES) feedback-driven propagation of surface anomalies onto the equator during boreal spring, (2) Trade Wind Charging (TWC) of equatorial subsurface heat content by NPMM-related surface wind stress curl anomalies in boreal winter and early spring, (3) The reflection of NPMM-forced ocean Rossby waves off the western boundary in boreal summer, and (4) A Gill-like atmospheric response associated with anomalous deep convection in boreal summer and fall. The South Pacific Meridional Mode (SPMM) also significantly modulates ENSO, and its interactions with the NPMM may contribute to ENSO diversity. Together, the NPMM and SPMM are also important components of Tropical Pacific Decadal Variability; however, future research is needed to improve understanding on these timescales.


Since 1950, the boreal spring NPMM skillfully predicts about 15–30% of observed winter ENSO variability. Improving simulated NPMM-ENSO relationships in forecast models may reduce ENSO forecasting error. Recent studies have begun to explore the influence of anthropogenic climate change on the NPMM-ENSO relationship; however, the results are inconclusive.


Pacific meridional mode El Niño-southern oscillation Extratropical-tropical interactions Teleconnections ITCZ shifts Energetics framework Climate prediction Climate modeling Climate variability Internal variability Climate dynamics Pacific variability Pacific decadal variability Subseasonal-to-seasonal forecasting Climate change Tropics Paleoclimate 



D.J.A is supported by the National Science Foundation Graduate Research Fellowship (NSF; DGE-1144086). Additional support was provided by NSF (OCE1419306) and NOAA (NA17OAR4310106). Thank you to Amaya et al. [22] for providing access to the atmospheric model simulations used in Fig. 4 of this work. Thank you to Art Miller, Pascal Polonik, Mike DeFlorio, and Shang-Ping Xie for their helpful comments throughout the course of this review. Thank you also to Antonietta Capotondi and one other anonymous reviewer for providing additional insightful comments that greatly improved the clarity and focus of the results. Thank you to the European Centre for Medium-Range Weather Forecasting (ECMWF) for developing the ERA5 reanalysis data used in this study, which is freely available at the Copernicus Climate Change Service (C3S;!/home). Thank you also to the UK Met Office Hadley Centre for maintaining the HadISST gridded data used in this study, which is available online ( Finally, thank you to the multi-institutional collaborative efforts of NMME, whose data is also readily available online (

Compliance with Ethical Standards

Conflict of Interest

On behalf of all authors, the corresponding author states that there is no conflict of interest.


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© Springer Nature Switzerland AG 2019

Authors and Affiliations

  1. 1.Scripps Institution of OceanographyUniversity of California-San DiegoLa JollaUSA

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