The quasi-geostrophic theory is the theoretical basis of the short-term weather forecast. Quasi-geostrophic motion equations of mid-latitude synoptic -scale movement are the core of quasi-geostrophic theory. Based on baroclinic two-layer model, quasi-geostrophic potential tendency equation and vertical motion equation can more clearly explain the movement and development of upper and surface weather systems. The movement of 500 hPa upper trough depends on the vorticity advection of 500 hPa, its development is determined by 500 hPa vorticity advection and differential vorticity advection between 250 and 750 hPa . The movement and development of cyclone depend on the positive temperature advection at 500 hPa and differential vorticity advection between 250 and 750 hPa. A case of snoptic system evolution demonstrates that quasi-geostrophic theory based on baroclinic two-layer model is conducive to the quick recognition of the characteristics of mid-latitude synoptic scale baroclinic development system, the understanding of the objective law of the development of the weather systems and the physical basis of numerical products.%准地转理论是短期天气预报的理论基础.针对中纬度大尺度运动得到的准地转运动方程组是准地转理论的核心.在斜压二层模式框架下,由准地转运动方程组得出的准地转位势倾向方程和准地转垂直运动方程,可以更为明确地解释高空和地面天气系统的移动和发展.结果显示:500 hPa高空槽的移动取决于本层的涡度平流,500 hPa高空槽的发展取决于本层的涡度平流和250与750h Pa层的微差温度平流;地面气旋系统的移动和发展取决于500hPa的正温度平流,250与750 hPa层的微差涡度平流.由实际天气过程对上述应用进行的分析表明,在斜压二层模式框架下得到的准地转位势倾向方程及准地转垂直运动方程,可以更好地确定中纬度天气尺度斜压发展系统的特征,并有助于对天气系统发展客观规律的了解和对数值预报产品内含的物理依据的认识.
展开▼
