The Relationship between the Quasi-Biennial Oscillation and Various Modes of Tropical Convective Activity

This study examines the relationship between the Quasi Biennial Oscillation (QBO) and tropical convective activity on various spatial and temporal scales. Previous studies have shown that the QBO can influence the amplitude of MJO convective activity exclusively during the boreal winter. This study tests the uniqueness of this relationship by examining possible relationships between the QBO and other modes of convective variability in the tropics. Consistent with previous studies, our regression and wavenumber-frequency spectral analysis of tropical convection had shown that the QBO most strongly impacts the tropical convective activity on MJO wavenumber-frequency domain during boreal winter. The QBO also seems to impact the seasonal mean and distribution of precipitation in the tropics, but its impact varies geographically. The activity of other convectively coupled equatorial waves and the diurnal cycle is found to be much less sensitive to the QBO. This result suggests that the uniqueness of the QBO impact on the MJO should be considered to understand the mechanisms on their relationship. Any future hypothesis or theories on the mechanisms of the relationship between the QBO and the MJO must be able to explain the uniqueness to the MJO and the seasonality of this relationship.