日本地球惑星科学連合2019年大会

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[E] 口頭発表

セッション記号 A (大気水圏科学) » A-OS 海洋科学・海洋環境

[A-OS08] ECS-Kuroshio and Ryukyu Current System -Observation, modeling and theory-

2019年5月29日(水) 15:30 〜 17:00 105 (1F)

コンビーナ:中村 啓彦(鹿児島大学 水産学部)、Xiao-Hua Zhu(Second Institute of Oceanography)、座長:Jae-Hun Park(Inha University)、中村 啓彦(鹿児島大学)

15:55 〜 16:10

[AOS08-07] Structure and variability of the Kuroshio current in the Tokara Strait

*劉 昭君1中村 啓彦2朱 小華1仁科 文子2郭 新宇3Menghong Dong1 (1.Second Institute of Oceanography, China、2.Kagoshima University, Japan、3.Ehime University, Japan)

キーワード:Tempo-spatial variations、Kuroshio、Tokara Strait

Transverse-vertical structure and temporal variability of the Kuroshio current across the Tokara Strait during 2003–2012 measured by ferryboat acoustic Doppler current profiler (ADCP) with a 2-km horizontal resolution and a 2-day interval are presented. The Kuroshio passing through the Tokara Strait exhibits a nearly permanent multicore velocity structure. The mean eastward Kuroshio transport is 25.84 Sv (1 Sv ≡ 106 m3 s-1) and the net baroclinic transport relative to 700 m is 19.57 Sv. The seasonal variation of the Kuroshio transport via the Tokara Strait is a “W”-shaped curve with a maximum in July and a second maximum in December–January. The baroclinic transport shows seasonal variation similar to that of the undecomposed transport, with a maximum in July. However, the barotropic transport displays a reversed seasonal variation—a “V”-shaped distribution—with a maximum in December. In the empirical orthogonal function (EOF) analyses of the cross-sectional velocity, with the exception of the well-known meander (EOF1: 41.1%) and transport (EOF2: 26.3%) modes, the third mode (EOF3: 19.2%) is first observed. The EOF3 mode exhibits a band-like structure, with a smaller horizontal scale than the first two EOF modes; such a band-like structure may be related to the wakes in the lee of the Tokara Islands. Additional analysis based on high-resolution JCOPE-T reanalysis data revealed that (1) many vortexes were generated around the Tokara Strait due to the strong flow-topography interaction; (2) the intensities of the island-induced wakes depend on the Kuroshio path position around the Tokara Strait.