The Relationship between Madden–Julian Oscillation Moist Convective Circulations and Tropical Cyclone Genesis

The Madden–Julian Oscillation (MJO) is a planetary-scale weather system that creates 30–60 day oscillation in zonal winds and precipitation the tropics. Its envelope of enhanced rainfall forms over Indian Ocean moves slowly eastward before dissipating near Date Line. MJO modulates tropical cyclone (TC) genesis, intensity, landfall Indian, Pacific, Atlantic Oceans. This study examines mechanisms by which alters TC genesis. In particular, circulations are partitioned into Kelvin Rossby waves for each developing, mature, stages convective envelope, locations genesis related to these circulations. Throughout MJO’s life cycle, inhibited east just west envelope. inhibition largely due vertical motion associated with wave circulation, as enhancement during developing stage. During mature stages, gyres intensify, creating regions low-level vorticity, favoring its west. Over 36-year period considered here, modulation increases intensification circulation.