摘要:利用多种资料对2011年第9号热带气旋“梅花”的两次路径转折过程进行诊断分析和数值模拟，结果表明：副热带高压、中纬度槽和越赤道气流等外部大环境场的变化对路径转向有影响，第一次路径转折期间，眼墙和螺旋云带分布变化不大；第二次路径转折前后，台风眼墙从双眼墙结构演变成明显的非对称结构，台风眼区发生了眼墙置换与合并，以及螺旋云带与眼墙合并过程。机制的定量分析表明：第一次转向期间，环境风场的纬向和经向分量对引导气流的贡献在83%以上，表明外部环境风场对其路径转向的影响较大，内部的风暴尺度风场对其路径转折的影响程度较小；第二次转向期间，风暴尺度场的纬向分量对引导引流贡献的百分比从23%上升到36%，经向分量对引导引流贡献的百分比介于35%~47%之间，表明内部非对称结构与外部大尺度环境流场对第二次路径转折都有影响。
关键词:台风“梅花”/
路径转折/
非对称结构/
螺旋云带/
眼墙
Abstract:A variety of data are used to analyze and study the two recurving processes of typhoon "Muifa", The results show that changes in the northwestern Pacific Subtropical high, the mid-latitude trough and cross-equatorial flows all have impacts on the two recurving processes of "Muifa". The internal TC structure such as the spiral cloud bands and eye wall changed little during the first recurving but they experienced huge changes during the second recurving with the formation of asymmetric structure, the replacement of eye wall and the merging of spiral cloud bands with eye wall. Numerical studies confirmed the above changes during the second recurving process. The mechanism study shows that the zonal and meridional components of environmental flow accounted for more than 83% of the steering flow for the first recurvature. For the second recurvature, the zonal component of storm-scale flow accounted for 23%-36%, while its meridional component accounted for 35%-47% of the steering flow.
Key words:Typhoon "Muifa"/
Track deflection/
Asymmetric structure/
Spiral cloud band/
Eye wall
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