동중국해와 필리핀해를 연결하는 캐라마갭을 통한 심층 Overflow

Abstract

The East China Sea includes the Okinawa Trough (in part deeper than 2000 m) between the continental slope and the Ryukyu Islands. In the Okinawa Trough, thermocline waters are exchanged with those of the Philippine Sea via the Kuroshio, while the deep waters below the thermocline can be exchanged only through the Kerama Gap with a sill depth of 1100 m. This study reveals temporal and spatial velocity-structures below the thermocline over the the Kerama Gap, cross-section mainly using data from moored current-meters during 2009/06–2011/06 and supplemented with outputs from a data-assimilated daily model provided by the Naval Research Laboratory. The temporal mean velocity field reveals a steady deep flow (> 10 cm/s) into the Okinawa Trough, which is clearly intensified on the northern slope of the Kerama Gap. The model outputs suggest that the deep flow is a branch of the Ryukyu Current, which is a deep current flowing northeastward along the eastern slope of the Ryukyu Islands. Most strong variations of the deep flow in the Kerama Gap are ascribed to unstable motions of the Ryukyu Current. while the deep waters below the thermocline can be exchanged only through the Kerama Gap with a sill depth of 1100 m. This study reveals temporal and spatial velocity-structures below the thermocline over the the Kerama Gap, cross-section mainly using data from moored current-meters during 2009/06–2011/06 and supplemented with outputs from a data-assimilated daily model provided by the Naval Research Laboratory. The temporal mean velocity field reveals a steady deep flow (> 10 cm/s) into the Okinawa Trough, which is clearly intensified on the northern slope of the Kerama Gap. The model outputs suggest that the deep flow is a branch of the Ryukyu Current, which is a deep current flowing northeastward along the eastern slope of the Ryukyu Islands. Most strong variations of the deep flow in the Kerama Gap are ascribed to unstable mo