Observations of the Madden Julian Oscillation during Indian Ocean Dipole events

The characteristics of Madden Julian Oscillation (MJO) development and propagation during Indian Ocean Dipole (IOD) events are presented in this study. We find that MJO activity over the Indian Ocean and Maritime Continent is enhanced during negative IOD and subdued during positive IOD. MJO events occurring during positive IOD have weaker convection and less organized wind anomalies than those occurring during neutral or negative IOD. These differences are starkest over the eastern Indian Ocean where the IOD has the greatest effect on low‐level humidity. Based on these observations and current MJO theories, we posit that the IOD primarily influences the MJO through its modulation of local low‐level moisture. Key Points The MJO is affected by the interannual variability associated with the IOD.MJO events tend to be weaker during +IOD than during neutral or −IOD.The IOD is likely affecting the MJO via changes in local low-level moisture.