ENSO 공간 구조에 대한 서태평양에서 해양성층화의 역할

Abstract

El Ni&ntilde o&#8211 Southern Oscillation (ENSO) variability is linked to both wind stress variations and recharge/discharge of oceanic heat content in the equatorial Pacific. The contribution of the surface momentum forcing to the ocean vertical baroclinic mode is important. We examined the changes in the relationship of oceanic vertical baroclinic mode-ENSO, and recent changes in warm pool SST and its linkage with ocean stratification. The mean SST over the western Pacific warm pool, where the wind stress variation is small, has experienced a shift from cool state to warm state in recent decades. Increased SST enhances the vertical stratification at the upper level. The warm pool SST variability is highly correlated with the change in maximum buoyancy frequency which is captured by the wind stress variations projecting onto the first baroclinic mode over the warm pool region. The ocean stratification change over the warm pool region, which is related to the changes in wind stress forcingprojecting onto the oceanic baroclinic modes, might contribute to change in El Ni&ntilde o structure in the observation during recent decades.rtical baroclinic mode is important. We examined the changes in the relationship of oceanic vertical baroclinic mode-ENSO, and recent changes in warm pool SST and its linkage with ocean stratification. The mean SST over the western Pacific warm pool, where the wind stress variation is small, has experienced a shift from cool state to warm state in recent decades. Increased SST enhances the vertical stratification at the upper level. The warm pool SST variability is highly correlated with the change in maximum buoyancy frequency which is captured by the wind stress variations projecting onto the first baroclinic mode over the warm pool region. The ocean stratification change over the warm pool region, which is related to the changes in wind stress forcingprojecting onto the oceanic baroclinic modes, might contribute to change in El Ni&ntilde o structure in the observation during recent decades.