Hydrographic structure and transport of the Oyashio south of Hokkaido and the formation of North Pacific Intermediate Water
Hydrographic structure and transport of the Oyashio south of Hokkaido and the formation of North Pacific Intermediate Water
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北海道以南亲潮的水文结构和输送以及北太平洋中层水的形成
DOI：
10.1029/1999jc000154
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发表时间：
2001
影响因子：
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通讯作者：
Y. Kawasaki
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作者：
I. Yasuda;Yutaka Hiroe;K. Komatsu;K. Kawasaki;T. Joyce;F. Bahr;Y. Kawasaki
通过 1998 年 6 月进行的电导率-温度深度和低声多普勒电流剖面仪 (LADCP) 测量，描述了北海道以南亲潮的水文结构和输送。北海道沿岸西南方向的亲潮输送量为 10.1 Sv，密度为 26.6-27.5σθ，其中 2.5 Sv 来自鄂霍次克海，7.6 Sv 来自西方亚北极环流（WSAG）。亲潮东北向逆流为 4.9 Sv。从北海道东海岸到亚北极锋地区的跨环流亲潮输送量估计为 5.2 Sv； 26.6~27.0σθ 范围内的 2.4 Sv 主要由低位涡鄂霍次克海水组成，27.0~27.5σθ 范围内的 2.8 Sv 主要来自 WSAG，表明鄂霍次克海水（WSAG 水）可能有助于北太平洋中层水（NPIW）上（下）部分的形成。亲潮水的含氧量低于亚北极锋以南的亚热带地区，密度为26.9~27.6σθ，可能是由于缺乏南极中间水（AAIW）的影响，含氧量较高的水可能沿北太平洋西边界和黑潮延伸带输送，增加了亚北极锋以南地区的含氧量。就在亚北极锋以南，观察到了一个冷的、新鲜的核心反气旋涡流，其核心盐度最低，这表明 NPIW 可能的形成过程。北海道附近西南亲潮的位涡最小值密度约为26.65σθ，低于1990年代初观测到的26.8-26.9σθ。这可能是因为鄂霍次克海和 WSAG 的位涡垂直剖面随着 20 世纪 90 年代中期亚北极太平洋发生的水团状态变化而发生显着变化 [Kawasaki, 1999]。
Hydrographic structure and transport of the Oyashio south of Hokkaido were described with conductivity-temperature-depth and lowered acoustic Doppler current profiler (LADCP) survey performed in June 1998. The southwestward Oyashio transport just off the Hokkaido coast was 10.1 Sv in the density of 26.6–27.5σθ, in which 2.5 Sv was from the Okhotsk Sea and 7.6 Sv was from the Western Subarctic Gyre (WSAG). The Oyashio northeastward countercurrent was 4.9 Sv. The cross-gyre Oyashio transport in the area from the east coast of Hokkaido to the Subarctic Front was estimated to be 5.2 Sv; 2.4 Sv in 26.6–27.0σθ was mainly composed of low potential vorticity Okhotsk Sea water and 2.8 Sv in 27.0–27.5σθ mostly from WSAG, suggesting that the Okhotsk Sea water (WSAG water) would contribute to the formation of the upper (lower) part of the North Pacific Intermediate Water (NPIW). The Oyashio water was lower in oxygen than in the subtropical areas south of the Subarctic Front in the density of 26.9–27.6σθ, possibly because of the absence of the Antarctic Intermediate Water (AAIW) influence with the relatively high oxygen water that might be transported along the western boundary of the North Pacific Ocean and along the Kuroshio Extension, increasing the oxygen in the areas south of the Subarctic Front. Just south of the Subarctic Front, a cold- and fresh-core anticyclonic eddy was observed with a salinity minimum in the core, suggesting one possible formation process of NPIW. The density of the potential vorticity minimum in the southwestward Oyashio near Hokkaido was at around 26.65σθ, which was lower than 26.8–26.9σθ observed in the early 1990s. This is possibly because the potential vorticity vertical profiles in the Okhotsk Sea and WSAG significantly changed corresponding to the water mass regime shift occurred in the Subarctic Pacific in the mid-1990s [Kawasaki, 1999].
HIRAI,M.：Am.J.Primatol.(1989)
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