The Characteristics of Synoptic and Subsynoptic Scale Environmental Field in the Period of Typhoon Unusual Northward Movement

A spatial filter is used to separate the typhoon environmental flow into a synoptic and a subsynopticscale components. Two unusual typhoon paths (Cecil (1982) and Abby (1983)) traviling towards are diagnosted. The results show that the anomalous path occurs in the period of synopticscale circulation adjustment from 500 hPa height field. This kind of typhoons has a tendency moving along the propagation direction of subsynoptic scale disturbance center when the typhoon travels unusually northwards. This is an interesting process, which may be responsible for the unusual typhoon path when the synoptic scale circulation is evidently weak. In light of kinetic energy field, typhoon movement is in accordance with the extending direction of the positive area of GKE (the generation of subsynoptic scale kinetic energy) during this period