Influence of Indian Ocean Tropical Cyclones on the Development of the Madden‐Julian Oscillation in December 2011

Abstract Previous studies demonstrate that the Madden‐Julian Oscillation (MJO) modulates tropical cyclone (TC) activity over various locations worldwide. Since TCs are associated with anomalous large‐scale circulations, they can influence the development of the MJO. However, the impact of TC on the MJO has not been thoroughly examined. This study investigates the influence of TC‐associated processes on the MJO development based on the analysis of a case observed during the Dynamics of the Madden‐Julian Oscillation field campaign. During the suppressed phase before the December 2011 MJO initiation, two TCs were active in the southern Tropical Indian Ocean (TIO). A dry air band within 10°S‐Eq is sustained by TC‐induced horizontal advection and descent, inhibiting large‐scale convection in the southern equatorial IO. Consequently, convection is triggered and develops only in the northern TIO around Eq‐10°N. The MJO initiates as convection develops south of the equator after the TCs dissipate.