Coastal circulation driven by bottom currents associated with tides around the continental shelf break

2019 Fiscal Year Final Research Report

• Project/Area Number: 15H03723
• Research Category: Grant-in-Aid for Scientific Research (B)
• Allocation Type: Single-year Grants
• Section: 一般
• Research Field: Meteorology/Physical oceanography/Hydrology
• Research Institution: The University of Tokyo
• Principal Investigator: Tanaka Kiyoshi 東京大学, 大気海洋研究所, 准教授 (20345060)
• Co-Investigator(Kenkyū-buntansha): 柳本 大吾 東京大学, 大気海洋研究所, 助教 (40260517) ; 西垣 肇 大分大学, 理工学部, 准教授 (70253763)
• Project Period (FY): 2015-04-01 – 2019-03-31
• Keywords: 海洋物理学 / 沿岸海洋力学

Outline of Final Research Achievements

Strong currents associated with internal tides near the bottom around a continental shelf break were investigated by conducting oceanographic surveys and performing numerical experiments. Shipboard and mooring monitoring surveys were conducted in the coastal ocean off the Sanriku region. A non-hydrostatic model and an ocean general circulation model were developed in the numerical experiments to investigate physical oceanographic processes over the coastal ocean including the continental shelf, continental slope, and deep basin. It was elucidated that internal mode motions are generated by convergence and divergence of flows imping on or separating from the continental slope, which originate from barotropic tides generated on the ocean basin. The internal mode motions play important roles in the coastal ocean circulation, because they are particularly strengthened near the bottom around the continental shelf and slope.

Free Research Field

海洋物理学

Academic Significance and Societal Importance of the Research Achievements

本成果は沿岸起源の海洋環境問題や漁業問題における喫緊の社会的諸問題の解決に必須であるのみならず、2011年3月に発生した東日本大震災で甚大な被害を受けた三陸地域の震災復興に対しても貢献する。例えば、本研究で明らかにされた大陸棚上の流況や水温分布の実態は、効率的な漁業活動や海洋土木工事の安全確保などに役立てられる。また、陸棚斜面に沿って湧昇する内部潮汐流は多量の栄養塩を水深200 mより深い層から沿岸陸棚域へもたらすことから、本研究で明らかにされた海底付近の強い流れや内部潮汐流の生成機構は、今後の沿岸生態系の維持と保全策の策定にも貢献する。