HR: 0800h
AN: OS41A-0152    [Abstracts]
TI: Topographically induced seasonal upwelling and ageostrophy of the coastal Tsushima Warm Current
AU: * Nakada, S
EM: snakada@riam.kyushu-u.ac.jp
AF: Department of Earth System Science and Technology, Kyushu University, 6-1 Kasuga- Koen, Kasuga-City, Fukuoka, Japan, Fukuoka, 816-8580, Japan
AU: Sasajima, Y
EM: sasajima@riam.kyushu-u.ac.jp
AF: Department of Earth System Science and Technology, Kyushu University, 6-1 Kasuga- Koen, Kasuga-City, Fukuoka, Japan, Fukuoka, 816-8580, Japan
AU: Hirose, N
EM: hirose@riam.kyushu-u.ac.jp
AF: Research Institute for Applied Mechanics Kyushu University, 6-1 Kasuga-Koen, Kasuga- City, Fukuoka, Japan, Fukuoka, 816-8580, Japan
AU: Yoon, J
EM: yoon@riam.kyushu-u.ac.jp
AF: Research Institute for Applied Mechanics Kyushu University, 6-1 Kasuga-Koen, Kasuga- City, Fukuoka, Japan, Fukuoka, 816-8580, Japan
AB: The seasonal variations of the coastal upwelling have been examined along the Japanese shelf area, the pathway of the coastal branches of the Tsushima Warm Current (TWC), the right-bounded current (coast to the right, looking downstream). The seasonal maps of water temperature at 200 m depth shows the rise of the main pycnoclines along the shelf slope due to the seasonal upwelling from May to September based on climatological temperature observations. An eddy-resolving ocean general circulation model is used to investigate the physical processes governing the seasonal upwelling. The TWC flows into the Japan Sea through the shallow Tsushima Straits and goes through the strong curvature of Japanese shelf seasonally forming the seasonal upwelling, a part of the secondary overturning circulation. A sensitivity experiment suggests that the seasonal upwelling is thermally driven by the density gradient between the buoyant TWC and the cold Japan Sea from April to October. Winter cooling plays a significant role as a preconditioning determining the strength of the upwelling. The dynamic balance across the TWC indicates that the subsurface seaward transport or lateral advection term maintains the overturning circulation or upwelling. The horizontal variation in the shelf topography locally critically influences the horizontal pattern of the lateral advection terms, the overturning circulation, and the upwelling.
DE: 4219 Continental shelf and slope processes (3002)
DE: 4255 Numerical modeling (0545, 0560)
DE: 4279 Upwelling and convergences (4964)
DE: 4516 Eastern boundary currents
DE: 4562 Topographic/bathymetric interactions
SC: Ocean Sciences [OS]
MN: 2007 Fall Meeting