科研之友
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摘要
The energy-Casimir method is employed to examine the stability of both non-parallel and parallel basic flows in the semi-geostrophic (SG) model in isentropic coordinates (ICs) based on the wave-activity invariants. It is found that the stability criteria for non-parallel basic flow under small-amplitude disturbances are more complicated than those for parallel basic flow, and the spatial structure of basic flow at a horizontal boundary has a great impact on the stability of both parallel and non-parallel basic flow. Results obtained in this work extend the stability results of Eliassen which are valid for parallel basic flow with non-normal geostrophic flow as lateral boundary conditions. It is shown that, although there is a strong similarity between the SG model in ICs and the shallow-water SG (SWSG) model, the finite-amplitude stability theorems for the latter model cannot be extended to the SG model in ICs and the reasons for the failure are discussed.
- 出版日期2015-7
