Observational study to quantitatively clarify bottom current passing through Main Gap of the Emperor Seamount Chain

2017 Fiscal Year Final Research Report

• Project/Area Number: 15K05283
• Research Category: Grant-in-Aid for Scientific Research (C)
• Allocation Type: Multi-year Fund
• Section: 一般
• Research Field: Meteorology/Physical oceanography/Hydrology
• Research Institution: The University of Tokyo
• Principal Investigator: Yanagimoto Daigo 東京大学, 大気海洋研究所, 助教 (40260517)
• Research Collaborator: MIYAMOTO Masatoshi 東京大学, 理学系研究科, 大学院学生
• Project Period (FY): 2015-04-01 – 2018-03-31
• Keywords: 海洋深層循環 / 北太平洋 / 底層水 / 船舶観測 / 係留観測 / 測流

Outline of Final Research Achievements

Bottom current was directly measured by ADCP lowered from ship and a current-meter mooring system at Main Gap, which is the widest, deepest gap at 39N-40N in the Emperor Seamount Chain dividing the deep layer of the North Pacific into the east and west basins. As the result, we obtained a snapshot of horizontal distribution of bottom current, which is weak in the northern part of the gap while eastward current is strong enough to exceed 20 cm/s in the southern part. One-year average of current velocity directed eastward also at the mooring site in the northern part. In total, the bottom water flows eastward through the gap. Water characteristics did not indicate that the bottom water is Lower Circumpolar Deep Water (LCDW) originating from the Southern Ocean. We obtained a new image of the deep ocean circulation where LCDW may be strongly modified in the Northwest Pacific Basin and may flow into the Northeast Pacific Basin through Main Gap.

Free Research Field

海洋物理学