On the rapid intensification of Hurricane Wilma (2005). Part IV: Inner‐core dynamics during the steady radius of maximum wind stage
On the rapid intensification of Hurricane Wilma (2005). Part IV: Inner‐core dynamics during the steady radius of maximum wind stage
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DOI：
10.1002/qj.3339
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发表时间：
2018-10
影响因子：
8.9
通讯作者：
Nannan Qin;Da‐Lin Zhang;W. Miller;C. Kieu
中科院分区：
文献类型：
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作者：
Nannan Qin;Da‐Lin Zhang;W. Miller;C. Kieu
最近的研究表明，一些飓风可能在没有收缩最大风半径(RMW)的情况下经历快速增强(RI)。本文使用2005年威尔玛飓风的云分辨中尺度模式预报来检验是什么控制了RMW收缩，以及飓风如何在没有收缩的情况下经历RI。结果表明，在行星边界层内和边界层上方，控制相对湿度收缩的过程是不同的。在边界层中，径向流入对收缩有贡献，而摩擦耗散起抑制作用。在边界层以上，径向外流和垂直运动是影响相对分子质量收缩的两个主要因素，径向外流对其有抑制作用。对绝对角动量(AAM)的预算分析表明，当RMW收缩时，径向AAM通量辐合是造成边界层最大自旋上升的主要过程，而AAM垂直通量散度和摩擦力则相反。然而，在无RMW收缩的RI期，眼壁局部AAM的趋势比收缩RI时的幅度更小，宽度更窄。此外，在PBL中，随随时间变化的RMW而变化的AAM随着时间的推移而减小，在收缩阶段几乎保持不变，而在非收缩阶段则增加。这些结果揭示了RMW收缩和RI的不同约束，并有助于解释为什么RMW停止收缩后飓风涡旋仍然会增强。
Recent studies show that some hurricanes may undergo rapid intensification (RI) without contracting the radius of maximum wind (RMW). A cloud‐resolving mesoscale model prediction of Hurricane Wilma (2005) is used herein to examine what controls the RMW contraction and how a hurricane could undergo RI without contraction. Results show that the processes controlling the RMW contraction are different within and above the planetary boundary layer (PBL). In the PBL, radial inflow contributes to contraction, whereas frictional dissipation acts as an inhibiting factor. Above the PBL, radial outflow and vertical motion are the two main factors governing the RMW contraction, with the former inhibiting it. A budget analysis of absolute angular momentum (AAM) shows that the radial AAM flux convergence is the major process accounting for the spin‐up of the maximum rotation in the PBL as the RMW contracts, while the vertical flux divergence of AAM and the friction oppose the spin‐up. During the RI stage with no RMW contraction, the local AAM tendencies in the eyewall are however smaller in magnitude and narrower in width than those during the contracting RI stage. In addition, the AAM following the time‐dependent RMW decreases with time in the PBL and remains nearly constant aloft during the contracting stage, whereas it increases during the non‐contracting stage. These results reveal different constraints for the RMW contraction and RI, and help explain why a hurricane vortex can still intensify after the RMW ceases contraction.