Modeling of El Nio Events Using a Simple Model

V. N. Stepanov

Proudman Oceanographic Laboratory, Liverpool, England, UK

E-mail: vst@pol.ac.uk

Received December 12, 2007; in final form, March 12, 2008

Abstract—In this paper, we present the results of modeling of El Nio events using a simple model of a clas-
sical oscillator with decay under external forcing. The sea surface temperature in the East Pacific and the mean
thermocline depth in the Equatorial Pacific correspond to the roles of the momentum and position, respectively. The
external forcing of the system is determined by two factors: the short-period meridional mass fluctuations in the
Pacific sector of the Southern Ocean due to the joint effect of the atmospheric variability over the Antarctic Circum-
polar Current, bottom topography, and coastlines; and the variability of western winds in the tropics. Under such con-
ditions, oscillations of El Nio type arise in the model as a result of propagation of signals generated in the Southern
Ocean (due to the fluctuations of meridional transport fluxes and the variability of western winds in the tropics). These
signals propagate over the Equatorial Pacific as fast wave processes. It is shown that external forcing is the main factor
in establishing the oscillation pattern of the model characteristics variability.

DOI: 10.1134/S0001437009030023

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