Eddy generation and evolution in the North Pacific Subtropical Countercurrent(NPSC) zone  

作　　者：康霖 王凡 陈永利 

机构地区：[1]Institute of Oceanology,Chinese Academy of Sciences [2]Key Laboratory of Circulation and Waves,Chinese Academy of Sciences [3]Graduate University of Chinese Academy of Sciences

出　　处：《Chinese Journal of Oceanology and Limnology》2010年第5期968-973,共6页中国海洋湖沼学报（英文版）

基　　金：Supported by the Key Program of the Knowledge Innovation Program of the Chinese Academy of Sciences (No.KZCX1-YW-12-04);the National Basic Research Program (973 Program) (No.2006CB403601)

摘　　要：The seasonal generation and evolution of eddies in the region of the North Pacific Subtropical Countercurrent remain poorly understood due to the scarcity of available data.We used TOPEX/POSEIDON altimetry data from 1992 to 2007 to study the eddy field in this zone.We found that velocity shear between this region and the neighboring North Equatorial Current contributes greatly to the eddy generation.Furthermore,the eddy kinetic energy level(EKE) shows an annual cycle,maximum in April/May and minimum in December/January.Analyses of the temporal and spatial distributions of the eddy field revealed clearly that the velocity shear closely related to baroclinic instability processes.The eddy field seems to be more zonal than meridional,and the energy containing length scale shows a surprising lag of 2-3 months in comparison with the 1-D and 2-D EKE level.A similar phenomenon is observed in individual eddies in this zone.The results show that in this eddy field band,the velocity shear may drive the EKE level change so that the eddy field takes another 2-3 months to grow and interact to reach a relatively stable state.This explains the seasonal evolution of identifiable eddies.The seasonal generation and evolution of eddies in the region of the North Pacific Subtropical Countercurrent remain poorly understood due to the scarcity of available data. We used TOPEX/POSEIDON altimetry data from 1992 to 2007 to study the eddy field in this zone. We found that velocity shear between this region and the neighboring North Equatorial Current contributes greatly to the eddy generation. Furthermore, the eddy kinetic energy level （EKE） shows an annual cycle, maximum in April/May and minimum in December/January. Analyses of the temporal and spatial distributions of the eddy field revealed clearly that the velocity shear closely related to baroclinic instability processes. The eddy field seems to be more zonal than meridional, and the energy containing length scale shows a surprising lag of 2-3 months in comparison with the 1-D and 2-D EKE level. A similar phenomenon is observed in individual eddies in this zone. The results show that in this eddy field band, the velocity shear may drive the EKE level change so that the eddy field takes another 2-3 months to grow and interact to reach a relatively stable state. This explains the seasonal evolution of identifiable eddies.

关 键 词：TOPEX/POSEIDON altimetry eddy field EKE velocity shear North Pacific SubtropicalCountercurrent 

分 类 号：P731.2[天文地球—海洋科学]