Oceanic Rossby Wave Influence on Madden-Julian Events from 1998—2012: An Observational Study

The Madden-Julian Oscillation (MJO) and the associated intraseasonal variability in rainfall have a significant impact on Southeast Asian agriculture, economies, and livelihood. Predicting when convection events associated with the MJO will occur is thus of great importance. More accurate understanding of air-sea interaction processes could improve the ability of computational models to forecast MJO-related convection events. Accordingly, this study provides observational evidence for the role of ocean dynamics and air-sea interaction in the initiation and propagation of Madden-Julian (MJ) events and other local convective events in the Tropical Indian Ocean. We examine satellite-measured sea surface height (SSH), sea surface temperature (SST), outgoing longwave radiation (OLR), and surface wind data for a fourteen-year period to thoroughly document evidence of oceanic Rossby waves occurring prior to and concurrent with MJ events in the Tropical Indian Ocean. In order to discover the role of ocean dynamics in affecting surface heat and moisture fluxes during convection initiation and development, particular emphasis is placed on oceanic Rossby waves that are accompanied by positive SST anomalies. Furthermore, we compare the ability of several MJO indices to identify convection events that exhibit ocean dynamical influence, providing additional insight into the utility of those indices.