A NUMERICAL EXPERIMENT OF CYCLOGENESIS AND THE DEVELOPMENT OF DISTURBANCES
Liu Ruizhi(Institute of Atmospheric Physics, Academia Sinica)
A numerical experiment has been carried out to study the mechanism of cyeloge-nesis and the development of disturbances. We first design an idealized field of temperature and pressure, which consists of the jet-like zonal circulation and some non-zonal waves superimposed on it. This idealized field is very sim lar to the actual synoptic situation. Then we use a six-level splitting primitive model to make the prediction with this idealized field as an initial one. The results show that if a disturbance like a frontal zone in the lower troposphere is superimposed on the zonal circulation, a frontal cyclone will quickly develop and then gradually become an occluded one. Its life cycle is similar to that of the actual frontal cyclone in the synoptic map. However, if there is a disturbance superimposed on the zonal circulation in the middle troposphere, the cyclone will be slowly formed near the surface and its intensity is weaker. 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.