QBO Modulation of the MJO-Related Precipitation in East Asia

Abstract

This study revisits precipitation change in East Asia caused by the Madden-Julian oscillation (MJO) and its interannual variation due to the quasi-biennial oscillation (QBO). Specifically, boreal-winter precipitation, derived from weather stations across China, Korea, and Japan, is examined for MJO phases 2-3 and 6-8. Consistent with previous findings, precipitation in southern China and southern Japan increases by up to 36% during MJO phases 2-3, when the MJO convection is located in the Indian Ocean. In contrast, during MJO phases 6-8, precipitation decreases by 13%. More importantly, these MJO-related precipitation anomalies become larger and more organized when the QBO is in its easterly phase. The difference in precipitation anomalies between the QBO easterly and westerly phases is approximately 40% for MJO phases 2-3 and 70% for MJO phases 6-8 from southern China to Japan. This result reaffirms that the QBO can affect surface weather in the northern extratropics through MJO teleconnection.