对东海热带气旋登陆后路径趋势的若干探讨

FACTORS AFFECTING THE TRACK OF TROPICAL CYCLONES AFTER LANDFALL IN EASTERN CHINA

关键词:  热带气旋  登陆后  路径趋势  影响因素

Key words:  tropical cyclone  track after landfall  moving tendency  effect factors

摘要:

应用相关分析与合成分析方法分析了影响东海热带气旋登陆后路径趋势的若干因素,结果表明:登陆后路径趋势随时间和登陆地点的变化分布说明热带气旋登陆后路径仍受基本气流的引导和制约;热带气旋登陆时的惯性和地转力的变化对东海热带气旋登陆后的路径趋势有一定影响;环境场及其变化对东海热带气旋登陆后路径有较大影响,尤其对流层中层流场对登陆后的热带气旋的移动仍有明显的引导作用;中国东部至黄海区域是环境场影响东海热带气旋登陆路径趋势的关键区,当区域内的西北太平洋副热带高压加强西伸,西风槽北撤时,东海热带气旋登陆后在副高南侧东风气流引导下向内陆西行至消亡,当区域内副高减弱东退,西风槽南压时,东海热带气旋登陆后受副高西侧偏南气流与西风槽前西南气流引导转向后入海;东海热带气旋登陆前的环境场对登陆后路径趋势影响相对较小,登陆后12～24小时是登陆后路径趋势受环境场影响的敏感时段,环境场的变化对登陆后路径趋势的影响要比当前环境场的影响超前6小时。

Abstract:

The correlation and composite analyses are carried out in this paper to study major factors affecting the track of tropical cyclones (TCs) after their landfall in Eastern China. The mid-tropospheric environmental steering flow is found to dominate the movement of a TC even after landfall,with the inertia and Coriolis force two other subordinates. A key region is discovered covering the east of China and Yellow Sea,in which the environmental flow significantly affects the movement of TCs making landfall in Eastern China. When the subtropical high in this region strengthens and extends westward,accompanied by northward shrink of the westerly trough,the TC tends to move westward after landfall and disappear inland. However,when the subtropical high in this region weakens and shrinks eastward,accompanied by southward push of the westerly trough,the TC tends to recurve after landfall and re-enter the sea at a location to the north of the site of landfall. The environment before the landfall of a TC has little impact on its post-landfall track,which is sensitive to the environmental change 12～24 hours after landfall. A 6-hour lag is found between the environmental change and the movement of a TC after landfall.