Numerical calculations on the phase velocity and growth rate of topographic Rossby wave

Aim The effects of topographic gradient on the phase velocity and growth rate of Rossby wave are investigated in terms of a shallow water model with topography.Methods The calculation is conducted by use of solving a eight-value problem about complex phase velocity on β-plane numerically. Results The greater the topographic gradient and the longer the wave length, the slower the phase velocity of the topographic Rossby wave, and the wave will be stationary or propagate westward when the wave length is longer enough with a greater topographic gradient.Conclusion The phase velocity of Rossby wave will be slower and the perturbation will become unstable when the effect of topography is included in the model, and the wave length of the most unstable wave is increasing with the strength of basic west flow, which is about 2 400～2 500 km (3 000 km) for basic flow 10 m/s (20 m/s).