On the Year-to-Year Change in Subarctic Water Characteristics Around the Kuril Islands

• Main Author: Yasuhiro Kawasaki
• Other Authors: The Pennsylvania State University CiteSeerX Archives
• Format: Text
• Language: English
• Subjects: Okhotsk; Oyashio; Pacific; okhotsk sea; Subarctic
• Online Access: http://citeseerx.ist.psu.edu/viewdoc/summary?doi=10.1.1.360.2009; http://www.pices.int/publications/scientific_reports/Report12/kawasaki_revf.pdf

A counterclockwise circulation centered approximately at 50°N 165°E is seen in the western Subarctic Pacific Ocean. The Oyashio makes up the southwestern rim of this circulation, and flows southwestward along the Kuril Islands and the eastern coast of Hokkaido. The water characteristics of the Oyashio show a considerable seasonal change due to the direct influence by the Okhotsk Sea (Kono and Kawasaki, 1997). The seasonal change in subsurface waters beneath the pycnocline is less those above the pycnocline, and we consider only the data taken in the same seasons every year. We confine our attention to the subarctic dichothermal (inter-cooled) water, which shows considerable year-to-year change due to the yearly variations in winter cooling and in global climate conditions. In this study, we analyze the data of subsurface water deeper than pycnocline depth observed around the Kuril Islands, and discuss the yearly change in water characteristics of the subarctic. Bussol Strait, the sill depth of which is 2200 m, is one of the main straits connecting the North Pacific Ocean with the Okhotsk Sea. The Hokkaido National Fisheries Research Institute (HNFRI) is continuing observations along a line which is passes through Bussol Strait (NU-line) by using the R/V Hokko-Maru belonging to HNFRI, every year since 1988. The location of the observational stations are shown in Figure 1. Annual observations are made from late August to early September. Kawasaki and Kono (1994) discussed the characteristics of subarctic waters of the Western