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Tsunogai, Shizuo*; Kawada, Kentaro*; Watanabe, Shuichi*; Aramaki, Takafumi
Journal of Oceanography, 59(5), p.685 - 693, 2003/10
Times Cited Count：28 Percentile：48.12(Oceanography)The water column distributions of CFC (chlorofluorocarbon) were determined twice in 2000 and 2001 in the northwestern Japan Sea. In 2000, the CFC-11 concentration decreased almost exponentially with depth from 6 pmol/kg at a few hundred m deep to 0.3 pmol/kg or less at the bottom of about 3400 m depth at 3 stations about 300 km off Vladivostok. In 2001, the CFC-11 concentration increased extremely up to 2 pmol/kg in the bottom water, while it did not increase at a station about 450 km away to the northeast. This is due to the renewal of the bottom water replaced by the surface water flowing down along the continental slope. The increase in the CFC-11 concentration was observed even in the whole water column above 3000 m depth. The increase in inventory is almost four times larger than that in the bottom water below 3000 m depth and equals about 1/6 of the total inventory found in 2000. The increase also means that 3 % of the deep water was replaced by the recent surface water or the turnover time of the deep water to be about 30 years, if the turnover occurs every year.
Senju, Tomoharu*; Aramaki, Takafumi; Otosaka, Shigeyoshi; Togawa, Orihiko; Danchenkov, M. A.*; Karasev, E.*; Volkov, Y. N.*
Geophysical Research Letters, 29(7), p.53_1 - 53_4, 2002/04
The newly formed bottom water in the Japan Sea was observed in the summer of 2001 after the severe winter 2000-2001. The new bottom water, which was observed in the northwestern Japan Sea, showed low temperature, high salinity, high dissolved oxygen and low nutrients concentration compared to the old bottom water. The distribution of the bottom water indicates that the deep convection occurred in the area of south off Vladivostok, not the northern Japan Sea, and then the bottom water was advected to the observation area from the convection region. The record of current meters suggests that the deep convection occurred in the early-February, because strong flows faster than 10 cms-1 appeared abruptly from mid-February 2001. This formation event may contribute not only the relaxation of the anoxic trend in the bottom layer but also the spin-up of the thermohaline circulation in the Japan Sea.
