On the Role of Synoptic Eddies in MJO Initiation

In a moisture budget analysis in the lower troposphere, Zhao et al. found that initiation of the MJO over the western Indian ocean, is in part associated with advection of mean background moisture by the MJO flow. Yet, preliminary results utilizing ERA-interim reanalysis data show that by budgeting the moisture at 800 hPa only, advection of the background moisture by synoptic eddies is larger than the advection of the background moisture by MJO flow. This study investigates the reasons behind the diminished role of the synoptic eddies when the mean layer 1000 to 700 hPa is considered. Also, preliminary results show that westward moving waves interact constructively with the MJO signal, thus the moisture budget is repeated again for data filtered for eastward-moving systems.