The eastward subtropical countercurrent on isopycnal surface in the western North Pacific
The monthly circulations on isopycnal surface in the western North Pacific are calculated based on the Navy's Generalized Digital Environmental Model climatological temperature and salinity data on a 1/2°× 1/2° grid using a P-vector method. The eastward Subtropical Countercurrent (STCC) in the central subtropical gyre has been studied with emphasis on its spatial distribution, vertical structure, volume transport and its nearby eddy phenomenon. The results reproduce the observed feature of STCC, and reveal some new phenomena on isopycnal surface, such as: (1) Atσθ= 24.6, there is strong seasonal variability in the distribution, origin and flow status of STCC. There is no STCC in January, February and March. (2) From May to October, a branch of the Kuroshio Countercurrent to the south of Japan merges into STCC, which increases the velocity of STCC and widens its width. (3) The velocity vector field shows that STCC and nearby eddies coexist. (4) The eastward volume transport of STCC across 137.5°E is the strongest in summer with the maximum of 6.9 Sv ( 1 Sv ≡ 106 m3 s-1) in August, and weaker in spring and autumn with 1.7 Sv in April and 1.6 Sv in November. Most of the transports of STCC occur between isopycnal surfaces 24.0σθand 25.0σθ. (5) The distributions of the zonal flow along 137.5°E show that the flow core of STCC is between 24.3σθand 24.7σθ.
作 者： Li Rongfeng YOU Xiaobao Peter C.Chu 作者单位： Li Rongfeng,YOU Xiaobao(LASG, Institute of Atmospheric Physics, Chinese Academy of Sciences, Beijing 100029, China)Peter C.Chu(Department of Oceanography, Naval Postgraduate School, Monterey, CA 93943-5122, USA)
刊 名： 中国科学D辑（英文版） SCI 英文刊名： SCIENCE IN CHINA (EARTH SCIENCES) 年，卷(期)： 2005 48(7) 分类号： P9 关键词： P-vector method on isopycnal surface eastward subtropical countercurrent eddy phenomenon