A study on generation mechanism of a shallow sea front and its variabilities—lecture by the member awarded the Okada Prize of the Oceanographical Society of Japan for 1991— |
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| Authors: | Kazunori Akitomo |
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| Institution: | (1) Department of Geophysics, Faculty of Science, Kyoto University, 606 Kyoto, Japan |
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| Abstract: | The author reviews his study on generation mechanism of a shallow sea front and its variabilities awarded the Okada Prize
of the Oceanographical Society of Japan for 1991.
A new physical model is proposed for frontogenesis (nonhydrostatic model) in a shallow sea such as the Kii Channel during
winter. This model retains the vertical acceleration term in momentum equation to simulate properly phenomena of a large aspect-ratio
in the frontal region, such as gravitational convection induced by surface cooling.
Numerical experiments are carried out to examine the validity of the model by using vertically two-dimensional model basin.
Gravitational convection induced in the frontal region strengthens the horizontal convergence to form a remarkable front comparable
to the observed one and that this effect of convection surpasses that of a tenfold cooling rate in a usual model adopting
the hydrostatic approximation. It is also found that sharpness of front largely depends on horizontal eddy viscosity (diffusivity).
Water exchange process caused by fluctuations of front is examined by tracking numerous labeled particles. Gravitational convection
also plays an important role in this process by producing a large Lagrangian drift in the frontal region. |
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