The Role of Surface Fluxes in MJO Propagation through the Maritime Continent

The barrier effect of the Maritime Continent (MC) is a known hurdle in understanding the propagation of the Madden-Julian oscillation (MJO). To understand the differing dynamics of MJO events that propagate versus stall over the MC, a new tracking algorithm utilizing 30-96-day-filtered NOAA Interpolated OLR anomalies is presented. Using this algorithm, MJO events can be identified, tracked, and described in terms of their propagation characteristics. Latent heat flux from OAFlux and CYGNSS surface winds and fluxes are compared for MJO events that do and do not propagate through the MC. Events that successfully propagate through the MC demonstrate regional surface flux anomalies that are stronger, more spatially coherent, and have a larger fetch. The spatial scale of convective anoma-lies for events that successfully propagate through the MC region is also larger than for terminating events. Large-scale enhancement of latent heat fluxes near and to the east of the date line, equally driven by dynamic and thermodynamic effects, also accompanies MJO events that successfully propagate through the MC. These findings are placed in the context of recent theoretical models of the MJO in which latent heat fluxes are important for propagation and destabilization.

Automated summary

This study presents a new tracking algorithm that utilizes 30-96-day-filtered NOAA Interpolated OLR anomalies to identify and describe the propagation characteristics of MJO events that cross the Maritime Continent (MC). MJO events that successfully propagate through the MC exhibit stronger and more spatially coherent regional surface flux anomalies, as well as larger fetch. The study also finds a large-scale enhancement of latent heat fluxes near and to the east of the date line in MJO events that successfully propagate through the MC.