On Rossby Waves Forced by Traveling Atmospheric Disturbances in a Barotropic Bounded Ocean

[摘要] Investigated in this article is the dynamical response of a bounded barotropic ocean on the β-plane to zonally moving atmospheric disturbances whose characteristic time-scale is about one week and characteristic horizontal scale is several thousand kilometers. The solutions of the linearized vorticity equation are obtained for several cases with and without incorporation of physical processes such as the bottom friction, the horizontal diffusion, and the horizontal mass divergence.The result may be summarized as follows: (1) When the ratio of the atmospheric traveling velocity to the critical velocity exceeds unity, the mode which travels with the speed of atmospheric disturbances is dominant, as already indicated by Pedlosky (1965). The critical velocity is deter-mined by the latitudinal and longitudinal wave numbers of atmospheric disturbances. (2) When the ratio is unity, the flow patterns show the behaviour of standing wave. (3) When the ratio is smaller than unity, the reflection from the eastern and western boundaries is observed in the open sea. (4) When the ratio is negative, the atmospheric disturbances may excite the resonance on the oceanic motion.The effects of the bottom friction and the horizontal diffusion are shown to be minor over the range of time-scale considered here.The existence of the horizontal mass divergence dicreases the critical speed but hardly affects the amplitude of meridional velocity.

[学科分类] 大气科学