High-Resolution Ensemble HFV3 Forecasts of Hurricane Michael (2018): Rapid Intensification in Shear
High-Resolution Ensemble HFV3 Forecasts of Hurricane Michael (2018): Rapid Intensification in Shear
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DOI：
10.1175/mwr-d-19-0275.1
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发表时间：
2020-04
影响因子：
3.2
通讯作者：
A. Hazelton;Xuejin Zhang;S. Gopalakrishnan;W. Ramstrom;F. Marks;Jun A. Zhang
中科院分区：
文献类型：
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作者：
A. Hazelton;Xuejin Zhang;S. Gopalakrishnan;W. Ramstrom;F. Marks;Jun A. Zhang
FV3GFS是美国国家环境预测中心（NCEP）目前正在运行的全球预报系统（GFS），它结合了一个有限体积的立方球体动力核心（FV3）和GFS物理。在本研究中，FV3GFS用于了解热带气旋（tc）在切变中的快速强化（RI）。分析表明TC结构在像飓风迈克尔这样的复杂系统中的重要性，尽管垂直风切变超过20 kt (10 m s - 1)，但飓风迈克尔仍在墨西哥湾上空增强为5级飓风。Michael的RI使用全球巢FV3GFS集合进行检查，巢分辨率为3公里。整体的峰值强度范围为77 ~ 159 kt （40 ~ 82 m s−1）。通过强、弱成员的合成，比较了Michael的降水对称性、涡旋倾斜、湿度等方面的演变。850-200-hPa早期强、弱段垂直切变平均为22 kt （11 m s−1）。倾斜和湿度是强弱构件之间的两个区别因素。涡旋倾斜和加湿之间的关系是复杂的，其他研究表明两者对剪切强化都很重要。在这里，表明倾斜减少导致上切变湿化，因此是加剧的驱动因素。一个较强的初始涡和涡的早期演化似乎也是构件能够抵抗剪切环境的关键。
The FV3GFS is the current operational Global Forecast System (GFS) at the National Centers for Environmental Prediction (NCEP), which combines a finite-volume cubed sphere dynamical core (FV3) and GFS physics. In this study, FV3GFS is used to gain understanding of rapid intensification (RI) of tropical cyclones (TCs) in shear. The analysis demonstrates the importance of TC structure in a complex system like Hurricane Michael, which intensified to a category 5 hurricane over the Gulf of Mexico despite over 20 kt (10 m s−1) of vertical wind shear. Michael’s RI is examined using a global-nest FV3GFS ensemble with the nest at 3-km resolution. The ensemble shows a range of peak intensities from 77 to 159 kt (40–82 m s−1). Precipitation symmetry, vortex tilt, moisture, and other aspects of Michael’s evolution are compared through composites of stronger and weaker members. The 850–200-hPa vertical shear is 22 kt (11 m s−1) in the mean of both strong and weak members during the early stage. Tilt and moisture are two distinguishing factors between strong and weak members. The relationship between vortex tilt and humidification is complex, and other studies have shown both are important for sheared intensification. Here, it is shown that tilt reduction leads to upshear humidification and is thus a driving factor for intensification. A stronger initial vortex and early evolution of the vortex also appear to be the key to members that are able to resist the sheared environment.