Sloshing Model for ENSO

The El Nino southern oscillation (ENSO) behavior can be effectively modeled as a response to a 2nd-order Mathieu/Hill differential equation with periodic coefficients describing sloshing of a volume of water. The forcing of the equation derives from QBO, angular momentum changes synchronized with the Chandler wobble, and solar insolation variations. One regime change was identified in 1980. (See floating note)

💡 Research Summary

The paper proposes a novel, physics‑based framework for representing the El Niño Southern Oscillation (ENSO) as a sloshing phenomenon in a large water basin. By analogy with a liquid that oscillates in a container, the authors model the average sea‑surface height anomaly in the equatorial Pacific as the displacement variable of a second‑order linear differential equation with periodic coefficients, i.e., a Mathieu/Hill equation. The governing form is

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