Benthic front between the Japan Basin and the Yamato Basin in the Japan Sea

Senju, Tomoharu*; Isoda, Yutaka*; Aramaki, Takafumi; Otosaka, Shigeyoshi  ; Suzuki, Takashi  ; Kuma, Kenshi*; Mori, Kosuke*

Abyssal water mass distribution from the Yamato Basin to the Japan Basin in the Japan Sea was observed on the R/V Hakuho-Maru cruise, KH02-3 (October 14-19, 2002). The bottom layer in the Yamato Basin was occupied by the water of higher temperature and lower oxygen compared to that in the Japan Basin. As a result, a benthic front of potential temperature and dissolved oxygen was formed between the Yamato and Japan Basins. Dissolved oxygen and nutrients concentrations show that the bottom water in the Yamato Basin is older than that in the Japan Basin. This indicates the existence of the Yamato Basin Water, which is modified bottom water by the closed circulation in the Yamato Basin. The structure of the benthic front suggests an estuary-like circulation around the mouth of the Yamato Basin; outflow from the Yamato Basin lying on the inflow from the Japan Basin. The highest oxygen water was found on the slope of southern periphery of the Japan Basin. This is considered to be the bottom water from the west transported by the cyclonic circulation in the Japan Basin.