Reduction in vertical wind shear, enhancement of low-level cyclonic vorticity and an increase in mid-tropospheric humidity are found to be the main factors behind the MJO’s positive influence on TCs in various regions 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19. It has been observed that TCs tend to form in clusters in different basins coinciding with the favorable or active phase of the MJO 7. Thus, when the active phase of the MJO happens over a region, the large-scale environment becomes more favorable for cyclogenesis, leading to the formation and intensification of tropical cyclones (TCs) in that region 5, 6.

While the wet or active phase of the MJO is associated with enhanced convection, the dry or suppressed phase is less conducive for convection 3, 4. It is one of the most important meteorological phenomena at intraseasonal timescales with wide-ranging impacts on global weather and climate 1, 2, 3. The Madden–Julian Oscillation (MJO), a 30–60 days period oscillation is a dominant mode of variability in the tropical atmosphere.

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