Based on the Tropical Cyclone (TC) Yearbook's data of JMA from 1979 to 2007, statistical analyses were performed to study the extratropical transition ( ET) of tropical cyclones over mainland of China. Results indicated that there were 16 tropical cyclones over the mainland of China, which accounted for 8. 56% of the total number of tropical cyclones that made landfall on China during the 29 a, only 8 of these ET cases got strengthened after transition. In addition, the moist potential vorticity ( MPV ) and the dynamic, thermodynamic processes analyses of the 8 ET cases're-intensification revealed that the combination of the dynamic and thermodynamic processes was able to define a development region in which it was favorable for intensification of most ET cases over mainland of China during the 29 a. Moreover, the upper-level positive MPV propagated downward to low-level during the obvious re-intensification phase of ET, however, the upper-level positive MPV did not always propagate downward when the ET of TC was reinforced only a little.%利用1979-2007年日本气象厅热带气旋年鉴资料,对在中国大陆上发生变性的热带气旋进行了统计分析,结果表明:29 a间中国大陆上发生变性的热带气旋共有16个,占登陆中国热带气旋总数的8.56％,其中8个变性后加强.利用日本JRA-25再分析资料诊断分析了这8个变性加强热带气旋的湿位涡垂直分布特征以及影响热带气旋变性发展的热力、动力因子,结果表明:29 a间中国大陆上大部分变性热带气旋的再加强均与中高层动力因子和低层热力因子所组成的发展区密切相关；变性加强明显的热带气旋,其高层的正湿位涡下传至低层,而变性加强幅度较小的热带气旋,其高层正湿位涡并不一定会下传至低层.
展开▼
