摘要:本文采用中国气象局的最佳台风路径数据和美国国家环境预报中心1°×1°每6 h再分析资料作为研究工作的基本场，运用了分部位涡反演方法探讨影响2015年第15号超强台风“天鹅”路径突变的物理机制，得到以下结论：（1）就天气系统而言，“天鹅”整个移动过程中都受到周围环境场及引导气流的影响，主要的影响系统包括西北太平洋副热带高压、季风涡旋、邻近台风“艾莎尼”及台风外围反气旋；（2）定量分析了与各影响系统扰动位涡相关的引导气流矢量，发现整个过程中超强台风“天鹅”的移动始终受西北太平洋副热带高压的影响，其次是来自季风涡旋及台风外围反气旋的贡献，而当“天鹅”有向北转向趋势时，与外围反气旋相关的东北向引导气流导致了台风的路径北折；（3）进一步定量分析了总扰动位涡在不同高度层上相关引导气流的贡献，结果表明在垂直方向上对流层中层系统的引导气流矢量与“天鹅”的移动最为吻合，而形成于低层系统的偏南风气流与“天鹅”向北突然转向有着密切的联系，并在转向后逐渐向中高层发展增强。
关键词:台风/
位涡反演/
路径突变/
引导气流
Abstract:Based on the best track data from China Meteorological Agency and 6-h reanalysis data with a resolution of 1°×1° from National Centers for Environmental Prediction, this study conducts the piecewise potential vorticity inversion to reveal the dynamic mechanism by which the 15th super typhoon Goni in 2015 suddenly changed its track.The results are as follows.(1) From the perspective of synoptic system, Goni was affected by the large-scale background system and the steering flows including the Northwest Pacific subtropical high, the monsoon gyre, the typhoon Atsani and the peripheral anticyclone of Atsani during the whole lifetime of Goni.(2) On the basis of quantitative analysis of the steering flow inverted from potential vorticity perturbation associated with the four components, we find that the steering flow vector of Goni was always affected by the Northwest Pacific subtropical high, while the monsoon gyre and peripheral anticyclone played a secondary role.At the time when Goni turned northward suddenly, the steering flow associated with the peripheral anticyclone acted as a major factor that resulted in the abrupt northward turning.(3) The contribution of the total potential vorticity perturbation to the relevant steering flow at different altitudes is further analyzed quantitatively.Results show that the steering flow vector in the middle troposphere is in good agreement with the movement of Goni, and the southerly flow formed in the low-level system is closely related to Goni's abrupt northward turning and its subsequent enhancement in the upper troposphere after the abrupt turning.
Key words:Typhoon/
Potential vorticity inversion/
Sudden track change/
Steering flow
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