동중국해와 북서태평양 사이에 존재하는 케라마갭 통과류의 변동성에 대한 중규모 와류의 영향

Abstract

The Kerama Gap (KG), near the middle of the Ryukyu Island chain, is the deepest channel with a sill depth of 1050 m connecting the East China Sea (ECS) to the Northwestern Pacific. The observed mean flow through the KG from June 2009 to June 2011 is 2.0±0.7 Sv into the ECS. A good correlation is obtained between satellite altimeter-measured sea-level anomaly difference across the KG and 2-year-long in situ-measured volume transport, which allows us to produce 7-day interval 20-year time series of the KG volume transport. The twenty-year mean volume transport is 1.5±0.2 Sv with standard deviation of 2.5 Sv. Comparison of KG volume transport time series with satellite-measured sea surface height maps reveals that the KG transport fluctuations at 40&#8722 150-day periods is strongly affected by mesoscale eddies around the KG. Consequently, its interannual to decadal amplitude changes are associated with interannual to decadal eddy field changes to the east of the Ryukyu Island chain in the Northwestern Pacific, which also determine the time-varying correlations between the KG through flow and the Ryukyu Current volume transport south of Okinawa.e 2011 is 2.0±0.7 Sv into the ECS. A good correlation is obtained between satellite altimeter-measured sea-level anomaly difference across the KG and 2-year-long in situ-measured volume transport, which allows us to produce 7-day interval 20-year time series of the KG volume transport. The twenty-year mean volume transport is 1.5±0.2 Sv with standard deviation of 2.5 Sv. Comparison of KG volume transport time series with satellite-measured sea surface height maps reveals that the KG transport fluctuations at 40&#8722 150-day periods is strongly affected by mesoscale eddies around the KG. Consequently, its interannual to decadal amplitude changes are associated with interannual to decadal eddy field changes to the east of the Ryukyu Island chain in the Northwestern Pacific, which also determine the time-varying correlations between the KG through flow and the Ryukyu Current volume transport south of Okinawa.