Accurate parameterization of turbulent mixing processes in the abyssal ocean for embedding in next-generation global overturning circulation models

2015 Fiscal Year Final Research Report

• Project/Area Number: 24340109
• Research Category: Grant-in-Aid for Scientific Research (B)
• Allocation Type: Partial Multi-year Fund
• Section: 一般
• Research Field: Meteorology/Physical oceanography/Hydrology
• Research Institution: The University of Tokyo
• Principal Investigator: Hibiya Toshiyukii 東京大学, 理学(系)研究科(研究院), 教授 (80192714)
• Project Period (FY): 2012-04-01 – 2016-03-31
• Keywords: 乱流混合 / パラメタリゼーション / 深層海洋大循環 / 内部波 / 非線形相互干渉 / 潮汐流 / 海底地形 / 超深海

Outline of Final Research Achievements

An accurate representation of ocean mixing processes over rough bathymetry is essential in global circulation models. We perform a series of eikonal calculations for a wide range of parameters, namely, the amplitude (Uo) of tidal flow with semidiurnal frequency (Ω) and the horizontal wavenumber (k) of the bottom topography to see how upward propagating internal waves generated by tide-topography interactions donate their energy to dissipation through nonlinear interactions with the background internal waves. It has been shown that the resulting mixing hotspot becomes concentrated nearer the ocean bottom as k increases for kUo/Ω<1 independent of Uo, whereas it extends vertically upward as Uo increases for kUo/Ω>1 independent of k. An interpretation for these calculated results has been made in terms of the vertical group velocity and the life time for each of linear internal tides and quasi-steady lee waves emanating from the ocean bottom for kUo/Ω<1 and kUo/Ω>1, respectively.

Free Research Field

海洋物理学