Relationship between the stratospheric quasi-biennial oscillation and the spring rainfall in the western North Pacific

Abstract

The effects of the stratospheric quasi-biennial oscillation (QBO) on spring rainfall in the western North Pacific (WNP) are investigated using observational and reanalysis data for 1979-2012. After excluding the strong El Nino-Southern Oscillation events, composite analyses between opposite phases of the QBO are applied to the rainfall and related meteorological fields to show the differences in each QBO phase. In comparison with the easterly phase, during the westerly QBO, a midlatitude spring rainband extending from southeastern China to the east of the Japanese Islands is displaced southward, and thus, the spring rainfall over Korea and Japan exhibits a significant decrease. Such changes in the spring WNP rainfall are related to the location and intensity of the WNP subtropical high (WNPSH) and the East Asian jet (EAJ). The possible role of the QBO in modulating the WNPSH and the EAJ is discussed with regard to the strength of the Hadley circulation.