A NUMERICAL EXPERIMENT OF CYCLOGENESIS AND THE DEVELOPMENT OF DISTURBANCES

A numerical experiment has been carried out to study the mechanism of cyclogenesis and the develop-ment of disturbances. First, an idealized field of temperature and pressure is designed, which is very similar to the actual synoptic situation, consisting of the jet-like zonal circulation with some nonzonal waves superim-posed on it. Prediction is made by using a six-level splitting primitive model with the idealized field as an initial one. The results show that if a disturbance like a frontal zone in the lower troposphere is superim-posed on the zonal circulation, a frontal cyclone will quickly develop and then gradually become an oc-cluded one. Its life cycle is similar to that of the actual frontal cyclone on the synoptic map. However, if there is a disturbance superimposed on the zonal circulation in the middle troposphere, the cyclone with weaker intensity will be slowly formed near the surface. Finally, if the initial disturbance is located at the high-level, a situation like a cut-off low rather than a frontal cyclone will develop.