热带气旋在中低纬度环境场中的不同活动特征

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

利用1951～1996年的历史资料,统计分析并详尽比较了中、低纬度环境场中的热带气旋活动的不同特征,获得了一些有益的结果。如:约65 %(5月达90 %)的低纬度热带气旋能北上进入中纬度地区;在中纬度地区活动的热带气旋平均移向较低纬度偏东60 左右、移速则较低纬度大10 km/h以上;约60 %的热带气旋在中纬度地区消亡;热带气旋的平均强度在中、低纬系统的分界线附近最大等。为进一步揭示热带气旋与中、低纬度环流系统相互作用的不同特征奠定了基础。

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.