摘要:本文利用WRF模式，通过开展敏感性试验讨论了单个热带气旋（Tropical Cyclone, TC）——“鲇鱼（Megi）”影响下不同等压面上西太平洋副热带高压脊线的移动特征，并分析了Megi活动影响副高脊线垂直分布的可能机理。结果表明，Megi活动期间，副高脊线在TC的影响下总体发生了向南移动，且TC活动所导致的脊线南移在高层相对较大，而在低层相对较小。TC影响副高脊线垂直分布的可能机理为，副高脊线的经向运动受其附近纬向风异常的直接影响，而Megi活动所导致的脊线附近纬向风异常与温度异常总体满足热成风关系，当Megi活动造成副高脊线附近出现温度经向梯度异常时，纬向风异常会随高度增加而发生切变，因此会导致副高脊线的垂直分布状况发生改变。另外，利用温度倾向方程的诊断分析结果表明，TC活动所激发的脊线附近不同物理过程项的异常在时空剖面上有很大区别，其中温度水平平流异常和非绝热加热异常的作用主要可使大气温度异常升高，而温度的垂直输送异常则可使温度降低。总之，TC的热力效应对西太平洋副热带高压脊线垂直分布的影响十分显著。
关键词:热带气旋/
西太平洋副热带高压/
垂直结构/
数值试验
Abstract:The characteristics of the meridional movement of western Pacific subtropical high (WPSH) ridge lines at different pressure levels under the influence of a single tropical cyclone (TC), i.e., Megi, and its possible mechanisms are analyzed by conducting sensitivity experiments with WRF. The results show that the WPSH ridge lines shift southward under the influence of TC Megi. Moreover, the higher the ridge lines are, the more southward they move. The possible mechanisms are that the shift of WPSH ridge lines is directly affected by the zonal wind anomalies in its vicinity, and the zonal wind and temperature gradient anomalies near the ridge lines caused by TC Megi generally satisfy the thermal wind relationship. Therefore, under the influence of the temperature gradient anomalies near the ridge line caused by TC Megi, the zonal wind anomalies will change with altitude, which will affect the vertical distribution of WPSH ridge lines. In addition, the diagnostic analysis results of the temperature tendency equation show that the different physical processes near the ridge, which are stimulated by TC activities, exhibit quite different temporal and spatial distributions. Moreover, the horizontal advection and nonadiabatic heating anomalies caused by TC Megi mainly lead to the abnormal increase of atmospheric temperature. Meanwhile, the vertical transport anomalies mainly lead to the abnormal decrease of atmospheric temperature. Therefore, the thermal effect of TC activities plays an important role in the process of changing the vertical distribution of WPSH ridge lines.
Key words:Tropical cyclone/
Western Pacific subtropical high/
Vertical structure/
Numerical experiment
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