Quasi-Biweekly Oscillation over the South China Sea in Late Summer: Propagation Dynamics and Energetics

Abstract

Abstract The propagation dynamics and energetics of the quasi-biweekly oscillation (QBWO) over the South China Sea (SCS) in late summer [August–September (AS)] are investigated in this study. The QBWO originates from east of the Philippines and has a northwestward propagation. After arriving to the east of the SCS, the QBWO shifts to a westward migration and dominates over the SCS. The analyses of the vorticity budget suggest that the meridional wind anomaly could control the spatial migration of the vorticity anomaly through the β-effect term and further influences the movement of the convection anomaly. It implies that the meridional wind is a crucial factor to drive the propagation of the QBWO. The energetics of the QBWO is investigated to understand the maintenance of the QBWO, which indicates that the convection anomaly could affect the circulation anomaly through the energy conversions to maintain the QBWO.