NUMERICAL SIMULATION OF TYPHOON WINNIE(1997) AFTER LANDFALL PART Ⅱ: STRUCTURE EVOLUTION ANALYSIS

By use of the result of simulation in part I of this study, the characteristics of typhoon during transformation stage and re-intensification stage are analyzed in circulation and dynamical and thermodynamic structures. The main course during the transformation stage is the transform from a symmetric tropical cyclone to a baroclinic asymmetric cyclone. At the beginning of transformation stage, some characters remain as those of tropical cyclone though the intensity and distribution of variables have changed obviously. Also the transporting of warm and wet air from ocean is asymmetric distribution due to the change of underlying surface after landfall. At the end of transformation stage a frontal cyclone is formed, since that the front zone intruded into the cyclone center in the lower level, and the slant characteristics of circulation and dynamical structure associated with front are developed. The neutral cyclone developed again in the re-intensification stage after combining the west trough in the upper level, the import of warm and moist flow from sea when the cyclone located at Bohai Sea does favor of its development during the stage.