How systematic is organized tropical convection within the MJO?

Recent theories of the dynamics of the Madden Julian Oscillation (MJO) have been building on its multi-scale structure. While it is observed that much of the convection within the MJO envelope is related to higher frequency equatorial waves, it is not known to what extent this organization is systematic from one MJO event to another. For instance, it is of interest to know whether MJO favors waves of particular types and propagation direction, and how this variability changes seasonally. This work presents a wavenumber-frequency spectral analysis of the MJO convective envelope, which indicates that there is no strong preferred scale of high frequency organization that is ubiquitous to the MJO. This null finding supports the use of convective parametrizations in modeling the MJO since, while moist convection is likely critical to its initiation and maintenance, the particular details of that organization may not be critical for its prediction and simulation.