Dynamic Core of the MJO

This presentation introduces a theory in which the dynamic core of the MJO is described in terms of a harmonic oscillator that can be excited by stochastic forcing. The mechanism for selecting MJO scales comes from momentum damping. The resonant solution to the equation for a damped harmonic oscillator on an equatorial beta plane represents the equatorial Kelvin wave for small damping and large zonal wavenumbers and the MJO for large (3 – 5 days) damping and zonal wavenumber one. This theory demonstrates the distinction between the Kelvin wave and MJO and their continuous transition. In contrast to most other MJO theories that compete against each other, this theory embraces most other theories in that they provide possible sources of energy (forcing) to the dynamic core of the MJO.