The Influence of the Stratospheric Quasi-Biennial Oscillation on the Tropical Easterly Jet Over the Maritime Continent

Abstract

This study investigated the influence of the stratospheric quasi-biennial oscillation (QBO) on the tropical easterly jet (TEJ), using the ERA5 and QBO series of Singapore and Freie Universität Berlin. Since the 1980s, the easterlies of the TEJ over the Maritime Continent are weaker during easterly QBO (EQBO) than westerly QBO. QBO influences TEJ by affecting convection on the east and west sides of the Maritime Continent. The climatological rising movement on the west side of the Maritime Continent can reach a higher altitude than that on the east side, which implies the convections on the west side are likely to be more effectively promoted by the reduced stability near the tropopause during EQBO. The zonal asymmetry in the stability near the tropopause is also a possible cause for QBO modulating convection. QBO has a significant influence on the Asian summer monsoon and tropical/subtropical precipitation through modulating the TEJ.