The Influence of the QBO on the MJO-Related Rainfall Variability over the Maritime Continent

Abstract

AbstractThe stratospheric quasi-biennial oscillation (QBO) and tropospheric Madden–Julian oscillation (MJO) have a strong connection over the tropics during boreal winter. Observational analysis has shown that the MJO activity is relatively stronger during easterly QBO (EQBO) than during westerly QBO (WQBO). Using tropical Rainfall Measuring Mission Version 7 (TRMMV7) from 1998 to 2014, we investigate the impacts of the QBO phases on MJO-driven rainfall over the Maritime Continent from December to February. The results show that during EQBO (WQBO), daily rainfall anomaly associated with the wet phases of MJO is increased (decreased) by up to 3.3 mm/day (1.8 mm/day) especially over the eastern and southern regions of the Maritime Continent. Furthermore, during the EQBO the probability of extreme rainfall during the wet phases of MJO is significantly increased by up to 100% over the eastern and southern regions, with a stronger amplitude over the ocean than over the lands. MJO-related rainfall with respect to the different phase of MJO is associated with changes in cloud-radiative feedbacks due to the colder (warmer) tropopause temperature and upward (downward) vertical advection during QBOE (QBOW). These results suggest that QBO-MJO connection can alter large-scale convection and rainfall intensity and extremes over the Maritime Continent.KeywordsEasterly QBOIndonesiaMJORainfallWesterly QBO