1,5,1,2,4- 1Universidad Complutense de Madrid, Facultad de Ciencias Físicas, EMFTEL, Spain (francao@ucm.es)
- 2Universidad Complutense de Madrid, Facultad de Ciencias Físicas, FTA, Madrid, Spain
- 3University of California, AOC, Los Angeles (UCLA), Los Angeles, CA, United States,
- 4Centro Superior de Investigaciones Científicas-Universidad Complutense de Madrid (CSIC-UCM), IGEO, Madrid, Spain,
- 5Instituto Madrileño de Estudios Avanzados en Nanociencia (IMDEA-Nanociencia), Madrid, Spain
Introduction: Observational and modeling studies have examined the
interactions between El Niño-Southern Oscillation (ENSO) and the equatorial
Atlantic variability as incorporated into the classical charge-recharge oscillator
model of ENSO. These studies included the role of the Atlantic in the
predictability of ENSO but assumed stationarity in the relationships, i.e., that
models’ coefficients do not change over time. A recent work by the authors has
challenged the stationarity assumption in the ENSO framework but without
considering the equatorial Atlantic influence on ENSO.
Methods: The present paper addresses the changing relationship between
ENSO and the Atlantic El Niño using an extended version of the recharge
oscillator model. The classical two-variable model of ENSO is extended by
adding a linear coupling on the SST anomalies in the equatorial Atlantic. The
model’s coefficients are computed for different periods. This calculation is
done using two methods to fit the model to the data: (1) the traditional method
(ReOsc), and (2) a novel method (ReOsc+) based on fitting the Fisher’s Z
transform of the auto and cross-correlation functions.
Results: We show that, during the 20th century, the characteristic damping rate
of the SST and thermocline depth anomalies in the Pacific have decreased in
time by a factor of 2 and 3, respectively. Moreover, the damping time of the
ENSO fluctuations has doubled from 10 to 20 months, and the oscillation
period of ENSO has decreased from 60-70 months before the 1960s to 50
months afterward. These two changes have contributed to enhancing ENSO
amplitude. The results also show that correlations between ENSO and the
Atlantic SST strengthened after the 70s and the way in which the impact of the
equatorial Atlantic is added to the internal ENSO variability.
Conclusions: The remote effects of the equatorial Atlantic on ENSO must be
considered in studies of ENSO dynamics and predictability during specific
time-periods. Our results provide further insight into the evolution of the ENSO
dynamics and its coupling to the equatorial Atlantic, as well as an improved tool
to study the coupling of climatic and ecological variables.
How to cite: Cao-García, F. J., Crespo-Miguel, R., Polo, I., Mechoso, C. R., and Rodriguez-Fonseca, B.: ENSO coupling to the equatorialAtlantic: Analysis with an improved recharge oscillator model, EGU General Assembly 2026, Vienna, Austria, 3–8 May 2026, EGU26-21543, https://doi.org/10.5194/egusphere-egu26-21543, 2026.
