The Mean Kinematic Structure of the Tropical Cyclone Boundary Layer and Its Relationship to Intensity Change
The Mean Kinematic Structure of the Tropical Cyclone Boundary Layer and Its Relationship to Intensity Change
复制标题
热带气旋边界层的平均运动结构及其与强度变化的关系
DOI：
10.1175/mwr-d-21-0335.1
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发表时间：
2023
影响因子：
3.2
通讯作者：
Gamache, John
中科院分区：
文献类型：
--
作者：
Zhang, Jun A.;Rogers, Robert F.;Reasor, Paul D.;Gamache, John
本文研究了热带气旋边界层（TCBL）的方位角平均运动结构与风暴强度、强度变化和边界层上方涡旋结构之间的关系。利用机载多普勒雷达垂直剖面的复合资料探讨了这些关系，该剖面比通常使用的三维分析具有更高的垂直分辨率，因此可以更好地捕捉TCBL结构。结果表明，以入流层深度定义的BL高度在弱风暴中大于在强风暴中。强风暴早期最大切向风速半径外的入流层较非强风暴深。强风暴时RMW内BL辐合峰要大于非强风暴时。源自TCBL的上升气流集中在RMW附近，有利于增强tc，而源自TCBL的上升气流在RMW外跨越较大的径向范围，有利于非增强tc。在BL上方涡旋结构方面，RMW外切向风径向廓线衰减快的风暴（“窄”涡）在RMW外的入流层更深，RMW附近的入流更强，RMW附近的强上升气流更深更集中，外核区入流较慢的切向风廓线（“宽”涡）更弱。窄涡的强度变化也比宽涡的强度变化快，表明涡的形状、BL的运动结构和涡强度变化之间存在着重要的关系。这种关系通过比较每个涡旋形状的绝对角动量收支项进一步探讨。
This study investigates the relationship between the azimuthally averaged kinematic structure of the tropical cyclone boundary layer (TCBL) and storm intensity, intensity change, and vortex structure above the BL. These relationships are explored using composites of airborne Doppler radar vertical profiles, which have a higher vertical resolution than typically used three-dimensional analyses and, therefore, better capture TCBL structure. Results show that the BL height, defined by the depth of the inflow layer, is greater in weak storms than in strong storms. The inflow layer outside the radius of maximum tangential wind speed (RMW) is deeper in intensifying storms than in nonintensifying storms at an early stage. The peak BL convergence inside the RMW is larger in intensifying storms than in nonintensifying storms. Updrafts originating from the TCBL are concentrated near the RMW for intensifying TCs, while updrafts span a large radial range outside the RMW for nonintensifying TCs. In terms of vortex structure above the BL, storms with a quickly decaying radial profile of tangential wind outside the RMW (“narrow” vortices) tend to have a deeper inflow layer outside the RMW, stronger inflow near the RMW, deeper and more concentrated strong updrafts close to the RMW, and weaker inflow in the outer core region than those with a slowly decaying tangential wind profile (“broad” vortices). The narrow TCs also tend to intensify faster than broad TCs, suggesting that a key relationship exists among vortex shape, the BL kinematic structure, and TC intensity change. This relationship is further explored by comparisons of absolute angular momentum budget terms for each vortex shape.