"艾利"台风异常路径与登陆地点分析

2004年18号台风“艾利”的移动路径在登陆前发生了两次左折，是一次十分罕见的异常路径。从大尺度环流、天气尺度特征分析发现，双台风作用使两个台风产生逆时针旋转效应，及由东西环副高联成的东西向高压坝的阻挡作用，台风西北侧我国江南一福建的偏东一东北气流的加强和沿海地形摩擦效应的综合效果是造成台风“艾利”异常路径的原因。“艾利”台风第二次左折向西南方向移动，沿着福建海岸线的移动阶段，利用沿海多部雷达的高时空分辨率的定位，准确及时地反映了台风西折的动向，为防台抗灾提供了重要的信息，从一定程度上弥补了第二次左折路径预报存在一定偏差的不足。分析还发现，“艾利”台风在第二次左折前后，多普勒雷达速度图象上出现了明显的风速极值区不对称特征，西北象限风速极值大于其它象限的不对称分布可能是导致并维持AERE台风向西南方向移动的重要原因。最后，利用沿海地区稠密的自动气象站探测到的风和气压资料，较好地验证了雷达定位的准确性，同时能够更精确地判定台风的登陆点。

Analyses of abnormal path and landing site of Typhoon AERE

The marching path of No. 18 typhoon AERE in 2004 turns sharply to the left twice before its landing, and it is a very peculiar one. Analyses of large-scale circulations and synoptic characteristics indicate that the abnormal path of typhoon AERE is caused mainly by the synthetic effects of four factors, such as anticlockwise actions generated by two typhoons, blocking impacts produced by high pressure dam consisting of east and west parts of subtropical high, intensifications of east-northeast winds along the east coasts of south of the Yangtze River and Fujian Province over northwest of this typhoon, and friction functions of the marine topography. The second sudden left-turning to the southwestward is along the coastline of Fujian Province, and it is captured by multi-radars with high spatiotemporal resolution, so that the important information is provided to resist the typhoon disasters by the precise and timely monitoring, and furthermore, it complements the erroneous forecast to the second abrupt left-turning path. Additionally, around the time of the second left-turning of typhoon AERE, there appear obviously asymmetric characteristics of the extreme wind velocity on the Doppler radar pictures, and it is probably the reason that induces the second left-turning. Eventually, the data of wind and pressure explored by the dense auto-meteorological stations in the marine regions well validate the accuracy of radar positioning, and at the same time, they can determine the landing site of typhoon much more accurately.