THE SOUTH-BORDERLINE OSCILLATION OF MID-LATITUDE WEATHER SYSTEMS AND TROPICAL CYCLONE MOVEMENT

The interaction between tropical cyclone (TC) and mid-latitude weather system (MLWS) concerns with the relative distance of TC and MLWS. In this paper, with the TC yearbook data from 1951 to 1996, the effect of south-borderline oscillation of MLWS on the latitudinal distribution of TC movement is analyzed and some beneficial consequence is obtained. For instance, only 5% tropical cyclones are generated in mid-latitude zone (MLZ), but, about 65% tropical cyclones generated in low-latitude zone (LLZ) will move northward into MLZ. The TC in middle latitude moves northeastward, deflecting eastward by 60 degree, and 10 km/h faster than TC in low latitude. The movement velocity increases rapidly 5 latitudinal beyond the south-borderline of MLWS. About 60 % TC disappear in middle latitude, and the average location of TC disappearance is about 10 latitudes north of the south-borderline of MLWS.