A New MJO Theory

Substantial progress has been made in understanding the fundamental dynamics of the MJO during the past decades. Yet, there is no consensus on the dominant mechanism for the MJO. Most current ideas of MJO dynamics involved atmospheric deep convection and its interaction with moisture. This presentation introduces a new 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 without moisture. In contrast to most other MJO theories that compete against each other, this new theory embraces all other theories in that they provide possible sources of energy to the dynamic core of the MJO through, for example, atmospheric deep convection and its interaction with moisture. This theory supports the notion of a continuous transition between the equatorial Kelvin wave and the MJO. The theory produces Kelvin solutions with relatively small damping and an MJO solution with large damping.