Analysis with Isentropic Potential Vorticity on a Cold Wave in Southeastern Asia

The dynamical characteristics of a cold wave in southeastern Asia during 3—8 January 1983 were analysed with isentropic potential potential vorticity (IPV) charts. In the brewing stage of the cold wave there are following three factors that play important role for the formation, intensification and southward movement of transversal trough in the mid-troposphere, and for the enhancement of mid-troposphere cold dome and surface cold high. They are IPV advective process (specially northeastern jet), coincidence of the shear line between northeastern jet and northwesterly with IPV maximum line, and cooling process of upward northwestern flow. We believe IPV charts to be really effective for dynamic analysis of large scale weather process, and they are shown to be a useful tool for weather analysis and forecasting