Diverse controlling mechanisms and teleconnections of three distinctive MJO types

Abstract

In present study, three distinctive MJO types in boreal winter are documented and their controlling mechanisms and teleconnections are investigated with a synergetic glocal approach. For the rst time, it is revealed that the diverse nature of the MJO primarily results from different Tropical-Extratropical Interactions and associated internal atmospheric processes. Both the type-I and type-II are initiated over the western Indian Ocean (IO) by a dry zone around the eastern IO, while only the type-I can move out the IO and circulate around the globe. The type-III initiates over the western Paci c (WP) and can circulate the globe and trigger another successive event. The strong upper-level equatorial westerly over the IO-WP, resulting from upstream and extratropical in uences, suffocates the type-II MJO within the IO. On the other hand, the robust upper-level equatorial easterly over the IO-WP, also resulting from upstream and extratropical in uences, along with regional convective instability over the WP and the arrival of east-Asian cold-surge foster the development and eastward propagation of the type-III MJO. The downstream and extratropical teleconnections are primarily controlled by the associated convection over the tropical IO-WP sector for the type-I, but also strongly in uenced by the conditions over the extratropical WP for the type-II and type-III. Given that the MJO has been traditionally viewed as a tropical mode owing its existence to the coupling between organized convection and large-scale circulations, present ndings advocate the MJO as a global mode and call for more research on the involved Tropical-Extratropical Interactions in order to better understand and simulate the diverse nature of the MJO.