A barotropic channel model in β-plane is used to study the effect of topographic forcing on the formation and maintenance of blocking. The approximate analytical solution of potential vorticity equation can show the ...A barotropic channel model in β-plane is used to study the effect of topographic forcing on the formation and maintenance of blocking. The approximate analytical solution of potential vorticity equation can show the main property of the whole process of blocking. It is indicated that the topographic forcing is one of the main factors causing the blocking process. The results suggest that the nonlinear interaction plays a very important role in the stable 'Ω' situation of blocking. The atmospheric circulation with periodic and low-frequency oscillation, perhaps, is partly caused by topographic forcing.展开更多
In this paper, the linear stability of disturbance superimposed on basic state Rossby wave forced by topography is investigated, and pointed out that when a certain criterion is satisfied by the basic flow and the hei...In this paper, the linear stability of disturbance superimposed on basic state Rossby wave forced by topography is investigated, and pointed out that when a certain criterion is satisfied by the basic flow and the height of topography for the subresonance, the small disturbance may be unstable. Furthermore, we also compare the evolution of the instability disturbance with the development of blocking in the Pacific, and we suggested that the topographically forced Rossby wave instability may provide a possible mechanism for the development of blocking in the Pacific.展开更多
With the Fourier-expanding expression of isolated topography,the forcing of isolated topography is studied in this paper.In the initial condition of steady uniform west flow in β-plan channel model,the approximate so...With the Fourier-expanding expression of isolated topography,the forcing of isolated topography is studied in this paper.In the initial condition of steady uniform west flow in β-plan channel model,the approximate solution of quasi-geostrophic potential vorticity equation is obtained.The results indicate that a series of steady topographic standing and transient waves can be produced by the forcing of isolated topography.The wave can move eastward or westward according to the wave scales.The most slowly Rossby wave is the strongest wave.So is the standing wave corresponding to the wave number.The main action of topography is to produce these strong waves.It is suggested that action of topography is one of the main causes to pro- duce low frequency oscillation and long-range steady weather.展开更多
文摘A barotropic channel model in β-plane is used to study the effect of topographic forcing on the formation and maintenance of blocking. The approximate analytical solution of potential vorticity equation can show the main property of the whole process of blocking. It is indicated that the topographic forcing is one of the main factors causing the blocking process. The results suggest that the nonlinear interaction plays a very important role in the stable 'Ω' situation of blocking. The atmospheric circulation with periodic and low-frequency oscillation, perhaps, is partly caused by topographic forcing.
文摘In this paper, the linear stability of disturbance superimposed on basic state Rossby wave forced by topography is investigated, and pointed out that when a certain criterion is satisfied by the basic flow and the height of topography for the subresonance, the small disturbance may be unstable. Furthermore, we also compare the evolution of the instability disturbance with the development of blocking in the Pacific, and we suggested that the topographically forced Rossby wave instability may provide a possible mechanism for the development of blocking in the Pacific.
文摘With the Fourier-expanding expression of isolated topography,the forcing of isolated topography is studied in this paper.In the initial condition of steady uniform west flow in β-plan channel model,the approximate solution of quasi-geostrophic potential vorticity equation is obtained.The results indicate that a series of steady topographic standing and transient waves can be produced by the forcing of isolated topography.The wave can move eastward or westward according to the wave scales.The most slowly Rossby wave is the strongest wave.So is the standing wave corresponding to the wave number.The main action of topography is to produce these strong waves.It is suggested that action of topography is one of the main causes to pro- duce low frequency oscillation and long-range steady weather.
