The potential vorticity budget of multi-scale MJO models

Recently, Zhang and Ling (J.Atmos Sci. 2012) performed a comprehensive analysis of the potential vorticity budget of the Madden-Julian oscillation during its initiation and evolution. Biello and Majda have used the IPESD multi-scale framework of tropical dynamics to create kinematic models which distinguish MJO events forced by in-scale heating with ones forced by upscale fluxes of momentum and temperature from synoptic to MJO scales. In this study we use the results of Zhang and Ling as a benchmark to compare the different multi-scale models. In particular, a potential vorticity budget can be obtained in the multi-scale framework, and potential vorticity advection, in-scale generation, and upscale generation terms are compared.