The disruption of MJO propagation across the Maritime Continent
In order to understand why some events of the Madden-Julian Oscillation cross the Maritime Continent (MC) and others do not, regional cloud permitting modelling study and an analysis of MJO events observed over 35 year are performed. A pair of a propagating and a disrupted MJO events are considered for the modeling case study. A set of sensitivity simulations are performed where atmospheric lateral boundary, SST and land surface conditions are modified to examine the comparative roles of various processes in the disruption of MJO propagation across the MC. It is found that the latitude at which the MJO approaches the MC, SSTs and land surface conditions all play a role in the disruption. MJO events that approach the MC close to the equator and when the SSTs are warm and the MC land surface is warm and dry are most likely to be disrupted. Analysis of 132 MJO events observed between 1979 and 2013 confirms the modeling case study results and shows that seasonal variations in the combination of these three factors allows MJO events propagating across the MC along the summer hemisphere to make it across unaffected or even be strengthened.