A Semi-Implicit Semispectral Primitive Equation Model for Lake Circulation Dynamics and Its Stability Performance
✍ Scribed by Yongqi Wang; Kolumban Hutter
- Publisher
- Elsevier Science
- Year
- 1998
- Tongue
- English
- Weight
- 532 KB
- Volume
- 139
- Category
- Article
- ISSN
- 0021-9991
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✦ Synopsis
We present a three-dimensional numerical model for the shallow water equations, suitable for determining the wind driven currents in homogeneous and stratified lakes. The model is based on the semispectral primitive equation model (SPEM) originally developed by Haidvogel et al.; however, because of the relatively small water depths of inland lakes in comparison to the ocean, the explicit integration technique, employed in SPEM, requires excessively small time steps which lead to very long integration times. In this paper a semi-implicit temporal integration scheme is proposed with the aid of which time integrations through realistic time spans for inland lakes become economical. By means of a large number of test runs in which the time step, the mesh size, and the austausch coefficients are changed and the numerical stability and the convergence performances of the code are determined. Moreover, the new semi-implicit SPEM is tested as to whether it is now capable to predict or reproduce physically relevant processes that are commonly observed by physical limnologists. To this end, computational results for a homogeneous and stratified rectangle and Lake Constance are presented.