Ocean Circulation Modeling with K-Omega and K-Epsilon Parameterizations of Vertical Turbulent Exchange

Abstract

Purpose. The main goal of the work is to advance the ocean general circulation model by improving description of the processes of vertical turbulent exchange of heat, salt and momentum which significantly affect quality of reproducing the ocean circulation and thermohaline structure using the models based on a system of the ocean hydrothermodynamics primitive equations. Methods and Results. The main instrument of the research is the sigma model of the oceanic and marine circulation developed at the Marchuk Institute of Numerical Mathematics, RAS. In the incompressibility, hydrostatics and Boussinesq approximations, the system of equations is supplemented with the k - ω and k - ε parameterizations of the vertical turbulent exchange, the equations for which are solved by the splitting method applied to the physical processes. The equations are split into the stages describing transport-diffusion of the turbulence characteristics and their generation-dissipation. At the generation-dissipation stage, the equations for turbulent characteristics are solved analytically. At that, the stability functions resulted from application of the spectral algorithm are used. To assess quality of two parameterizations of the vertical turbulent exchange, the North Atlantic–Arctic Ocean circulation is numerically simulated and the upper ocean layer characteristics are studied. Conclusions. It is shown that the structure of the North Atlantic–Arctic Ocean large-scale fields is sensitive to choice of the vertical turbulence models. In particular, application of the k - ε parameterization is accompanied by a noticeably higher rate of involvement of the seasonal pycnocline waters in the developed turbulence zone than that resulting from application of the k - ω parameterization.

Keywords

• ocean circulation
• k-omega parameterization
• k-epsilon parameterization
• splitting method
• vertical turbulent exchange
• north atlantic