Abstract:Using the Penn State NCAR non hydrostatic mesoscale model (MM5), the later per iod of landfall of typhoon Matsa is simulated. A low pass filter is used to sep arate the flow into a larger and a sub synoptic scale component. Then the sub synoptic scale features of Matsa were investigated based on movable coordinate. From the view of the effect of terrain on the interactions between two scales, t he influence of terrain on tropical cyclone is proved to be non negligible furt her. The results are as follows: The existence of terrain helps to maintain the intens ity of tropical cyclone and the effect intensifies with the minishing of distanc e between the corner of cyclone and terrain. The intensification is more evident at upper troposphere. At low level the sub synoptic system converts smaller kinetic energy into tropical cyclone and gets more kinetic energy from tro pical cyclone if terrain is taken out. Meanwhile, the su b synoptic system gets more positive vertical vorticity from tropical cyclone. In a word, tropical cyclone dos not get but losses positive vertical vorticity i f without terrain.