Observational Analyses of Madden Julian Oscillation Propagation through the Maritime Continent

One region particularly susceptible to enhanced convective activity during the Madden Julian Oscillation (MJO) active phase is the Maritime Continent (MC). As the ascending branch of the MJO envelope reaches the MC, the convective signal sometimes propagates eastward through the MC and reaches the Western Pacific Ocean (a propagating event). However, the convective envelope may also decouple from zonal wind anomalies and weaken over the MC, not reaching the Western Pacific Ocean (a non-propagating event). Propagation of the MJO across the MC is currently the subject of multiple studies.

In this study, anomalies of atmospheric temperature, relative and specific humidity, mean sea level pressure, lower- and upper-tropospheric zonal and meridional wind components, and sea surface temperature from the NCEP-National Center for Atmospheric Research (NCAR) Reanalysis were compared for propagating and non-propagating MJO events. The Wheeler-Hendon Realtime Multivariate (RMM) MJO Index was utilized to differentiate between MJO phases and amplitudes. Additional emphasis was given to the interaction between Rossby and equatorial Kelvin waves and the active and suppressed MJO envelopes. The goal of this work was to better understand the physical mechanisms that favor MJO propagation across the MC.