摘要
In this study,the impact of environmental factors on tropical cyclone(TC)outer-core size was investigated for both migrating and local TCs in the South China Sea during the period 2001–2019.Among all the thermodynamic and dynamic factors,the low-level environmental helicity showed the strongest positive correlation with TC outer-core size.Large helicity favors the development and organization of convection in TCs,and the corresponding strong inflow and large angular momentum fluxes into the system is beneficial for the maintenance and enlargement of TC outer-core size.Besides,the asymmetric distribution of helicity may account for the asymmetry of TC outer-core size.Therefore,the environmental helicity,as an integrated dynamic factor,can provide an alternative view on TC outer-core size.
本文利用2001–2019年间的ERA5再分析数据集和热带气旋(TC)最佳路径观测,分析了中国南海TC的外围尺度与环境变量之间的关系.研究发现,低层环境螺旋度与TC外围尺度具有显著的正相关.大的环境螺旋度有利于TC外围对流的增强和组织化,与之对应的径向入流和角动量输送有利于TC外围尺度的维持或扩张.此外,螺旋度的非对称分布与TC外围尺度的非对称性结构也密切相关.环境螺旋度作为一个包含TC外围对流强度和组织化程度等信息的综合动力因子,为理解TC外围尺度变化提供了不同的视角.
基金
This work was supported by the National Key Research and Development Program of China[grant number 2017YFC1501603]
the National Natural Science Foundation of China[grant numbers 41675053,42175062,and 61827091].
