Current understanding of tropical cyclone structure and intensity changes – a review
Current understanding of tropical cyclone structure and intensity changes – a review
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DOI：
10.1007/s00703-003-0055-6
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发表时间：
2004-02
影响因子：
2
通讯作者：
Yuqing Wang;Chun‐Chieh Wu
中科院分区：
文献类型：
--
作者：
Yuqing Wang;Chun‐Chieh Wu
本文综述了热带气旋结构和强度变化的研究现状。近年来的研究主要集中在两个问题上：（1）在大气和海洋的热力学状态下，什么因素决定了热带气旋的最大位能强度？以及（2）哪些因素阻止TC达到其MPI？虽然MPI理论看起来很成熟，但最近对所谓超强度的研究提出了潜在的挑战。值得注意的是，各海盆中真实的TC所达到的最大强度普遍低于理论MPI所推断的最大强度，这表明内部动力和环境流的外部强迫对TC加强的抑制作用最大，限制了TC的强度。在众多的限制因素中，不利的环境条件，特别是内核区垂直切变引起的不对称性和眼壁区海洋上升流引起的海面冷却，被认为是TC到达MPI的主要障碍。然而，最近的研究表明，中尺度过程，造成不对称的TC核心区，在TC结构和强度变化中起着关键作用。这些包括内部和外部的螺旋雨带，对流耦合涡Rossby波，眼壁循环，并嵌入在TC环流中的中涡。外部环境气流也正是通过这些内核过程影响热带气旋的结构和强度变化。建议今后的研究重点是提高眼壁过程如何响应所有外部强迫和影响TC结构和强度变化的理解。热带气旋强度的快速变化（增强和减弱）涉及到不同尺度之间复杂的相互作用，值得进一步研究。边界层过程对热带气旋的形成、维持和衰减至关重要。在利用全球定位系统投下式探空仪测量飓风眼墙附近的边界层风来推断大风条件下的阻力系数方面取得了重大进展。这一突破可以减少地面通量计算中的不确定性，从而改善数值天气预报模式对TC强度的预报。
Current understanding of tropical cyclone (TC) structure and intensity changes has been reviewed in this article. Recent studies in this area tend to focus on two issues: (1)what factors determine the maximum potential intensity (MPI) that a TC can achieve given the thermodynamic state of the atmosphere and the ocean? and (2)what factors prevent the TCs from reaching their MPIs? Although the MPI theories appear mature, recent studies of the so-called superintensity pose a potential challenge. It is notable that the maximum intensities reached by real TCs in all ocean basins are generally lower than those inferred from the theoretical MPI, indicating that internal dynamics and external forcing from environmental flow prohibit the TC intensification most and limit the TC intensity. It remains to be seen whether such factors can be included in improved MPI approaches.Among many limiting factors, the unfavorable environmental conditions, especially the vertical shear-induced asymmetry in the inner core region and the cooling of sea surface due to the oceanic upwelling under the eyewall region, have been postulated as the primary impediment to a TC reaching its MPI. However, recent studies show that the mesoscale processes, which create asymmetries in the TC core region, play key roles in TC structure and intensity changes. These include the inner and outer spiral rainbands, convectively coupled vortex Rossby waves, eyewall cycles, and embedded mesovortices in TC circulation. It is also through these inner core processes that the external environmental flow affects the TC structure and intensity changes. It is proposed that future research be focused on improving the understanding of how the eyewall processes respond to all external forcing and affect the TC structure and intensity changes. Rapid TC intensity changes (both strengthening and weakening) are believed to involve complex interactions between different scales and to be worthy of future research.The boundary-layer processes are crucial to TC formation, maintenance, and decaying. Significant progress has been made to deduce the drag coefficient on high wind conditions from the measurements of boundary layer winds in the vicinity of hurricane eyewalls by Global Positioning System (GPS) dropsondes. This breakthrough can lead to reduction of the uncertainties in the calculation of surface fluxes, thus improving TC intensity forecast by numerical weather prediction models.