A simple quasi-geostrophic coupled ocean-atmosphere model |
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| Authors: | Liu Shikuo He Anguo |
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| Institution: | Department of Geophysics, Peking University, Beijing China 100871,Department of Geophysics, Peking University, Beijing China 100871 |
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| Abstract: | The quasi-geostrophic atmospheric and oceanic equations of momentum and thermodynamics with dissipation factors are used to create a simple coupled ocean-atmosphere model describing the large-scale shallow-water mo-tion. We discuss the ocean-atmosphere coupling effect in mid-high and low latitudes separately and analyze charac-teristics of which the oscillatory periods of coupled low-frequency modes (ocean mode) vary with the coupling fre-quency and latitudinal number. This can interpret the correlation between low-frequency oscillation and ocean-at-mosphere interaction. Then from the dispersion curves of atmosphere and ocean, we reveal effect of the coupling strength on the propagation of Rossby waves. The convection mechanism between the two modes is also discussed in view of the slowly varying wave train.The results show that Newtonian cooling and Rayleigh friction play a stable rule in oceanic Rossby waves, the period of coupled low-frequency mode grows with the increment of the coupling frequency. The larger the latitudinal number is, the more rapidly it grows. When the coupling frequency tends to critical value, the oceanic Rossby waves become static. When the ocean-atmosphere coupling strength grows to some degree, the propagation of oceanic Rossby waves will become opposite to its original direction. One part of the oceanic Rossby waves is converted into atmospheric Rossby waves, the energy conversion coefficient is also solved out. |
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