Oceanic Responses and Feedbacks to the Eastward Propagation of the Madden–Julian Oscillation in the Maritime Continent

The role of sea surface temperature [SST] in influencing eastward propagation of Madden-Julian Oscillation [MJO] events over the maritime continent [MC] is investigated using satellite and reanalysis data over the period of 1980 – 2012, during which there are 86 MJO events over the Indian Ocean, 51 of which traversed the MC into the western Pacific. The SST in the Indonesian Seas during the suppressed phase of these 51 MJO events is warmer by 0.5 °C than that associated with the MJO events that do not propagate over the MC. We argue that the warmer SST, which corresponds to increased surface turbulent air-sea heat flux, low-level moisture, and diurnal SST activity, serves as a favorable precondition for the MJO convection to propagate across the MC. During the MJO active phase, the SST-MJO coupling at El Niño Southern Oscillation [ENSO] timescale in the Indonesian Seas is sensitive to the thermocline depth and demonstrates stronger coupling during La Niña when the thermocline is deeper than during El Niño.