台风“鲇鱼”(1013)路径突变过程的成因分析

Cause analysis of sudden track change of Typhoon Megi(1013)

利用NCEP提供的GFS(Global Forecast System)再分析资料,对2010年西北太平洋最强台风"鲇鱼"(1013)路径突变的成因开展诊断分析,研究其影响系统、引导气流的演变特征等,并运用CPS(Cyclone Phase Space)方法对其生命史中的热力结构演变过程进行定量描述,重点分析路径突变前后各因子的变化。结果表明,"鲇鱼"移入南海后,冷空气南侵导致其热力结构发生变化,台风环流右侧较暖,此时引导气流微弱,"趋暖"运动占主导,首先引起路径向右偏转,随后引导气流转为西南气流并逐渐增强,在二者共同作用下,"鲇鱼"路径持续右转,逐渐向东北方向移动,完成路径突变。

A diagnostic study is carried out on the causes of sudden track change of Typhoon Megi（ 1013）using the NCEP-GFS（ National Centers for Environmental Prediction-Global Forecast System） analysis data. The evolution characteristics of circulation systems and steering flow are analyzed,and the quantitative description for the thermodynamical structure variation during the lifetime of Megi is carried out by means of CPS（ Cyclone Phase Space） method,focusing on the changes of parameters around the northward shift of the track. Results show that,after Megi moves over South China Sea,the cold air intrudes southward,leading to a shift of the thermodynamical structure of Megi,i. e.,the right of its motion is warmer than the left. Meanwhile,the steering flow is rather weak. Under this circumstance,the movement toward the warm air area plays a primary part,which leads to rightward shift of motion track of Megi at first. The steering current becomes northeastward and grows stronger subsequently. The combination of the two factors results in a persistent rightward shift of the track. Thus,Megi gradually moves northeastward,and the sudden track change process is completed.