Heartbeat of the Southern Oscillation explains ENSO climatic resonances

Bruun, JT, Allen, JI and Smyth, TJ 2017 Heartbeat of the Southern Oscillation explains ENSO climatic resonances. Journal of Geophysical Research: Oceans, 122 (8). 6746-6772. https://doi.org/10.1002/2017JC012892

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Official URL: https://doi.org/10.1002/2017JC012892


The El Ni~no-Southern Oscillation (ENSO) nonlinear oscillator phenomenon has a far reaching influence on the climate and human activities. The up to 10 year quasi-period cycle of the El Ni~no and subsequent La Ni~na is known to be dominated in the tropics by nonlinear physical interaction of wind with the equatorial waveguide in the Pacific. Long-term cyclic phenomena do not feature in the current theory of the ENSO process. We update the theory by assessing low (>10 years) and high (<10 years) frequency coupling using evidence across tropical, extratropical, and Pacific basin scales. We analyze observations and model simulations with a highly accurate method called Dominant Frequency State Analysis (DFSA) to provide evidence of stable ENSO features. The observational data sets of the Southern Oscillation Index (SOI), North Pacific Index Anomaly, and ENSO Sea Surface Temperature Anomaly, as well as a theoretical model all confirm the existence of long-term and short-term climatic cycles of the ENSO process with resonance frequencies of {2.5, 3.8, 5, 12–14, 61–75, 180} years. This fundamental result shows long-term and short-term signal coupling with mode locking across the dominant ENSO dynamics. These dominant oscillation frequency dynamics, defined as ENSO frequency states, contain a stable attractor with three frequencies in resonance allowing us to coin the term Heartbeat of the Southern Oscillation due to its characteristic shape. We predict future ENSO states based on a stable hysteresis scenario of short-term and long-term ENSO oscillations over the next century.

Item Type: Publication - Article
Subjects: Atmospheric Sciences
Data and Information
Earth Sciences
Marine Sciences
Meteorology and Climatology
Divisions: Plymouth Marine Laboratory > Science Areas > Marine System Modelling
Depositing User: Tim Smyth
Date made live: 14 Mar 2018 15:49
Last Modified: 25 Apr 2020 09:58
URI: https://plymsea.ac.uk/id/eprint/7677

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