Numerical Study on Evolution of Frontal Waves and Cyclogenesis
锋面波发展演变与气旋形成的数值研究

In this paper, the front is considered as a surface of zero-order discontinuity. In such a way, we designed a shallow water, two-layer model in fplane. The model is written in finite differences according to kinetic energy and potential etrstrophy conserving scheme. It is indicated that the evolution of frontal waves is selective to the scale of initial disturbance. The synoptic-scale disturbance can be evolved to large-amplitude frontal wave which is similar to occluded cyclone. When the scale of initial disturbance is decreased, the amplitude of frontal wave is also decreased. As a result, such a frontal wave has shorter life-time, and no structure of occluded cyclone. In addition, the evolution depends on Richardson number Ri. The less Ri is, the more intensely the frontal waves evolve. When a frontal wave evolves to an intense state, it is similar to a cyclone.