A New Time-Dependent Theory of Tropical Cyclone Intensification
A New Time-Dependent Theory of Tropical Cyclone Intensification
复制标题
热带气旋强化的新时间相关理论。
DOI：
10.1175/jas-d-21-0169.1
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发表时间：
2021
影响因子：
3.1
通讯作者：
Jing Xu
中科院分区：
文献类型：
--
作者：
Y. Wang;Y. Li;Jing Xu
本文利用边界层切向风收支方程，结合热力学准平衡边界层假设，导出了热带气旋(TC)强化速率(IR)的新方程。假定热带气旋在热风平衡中是轴对称的，有眼壁对流。随着风暴的加强，在边界层以上的自由大气中，TC进入潮湿的倾斜中性状态，这是最近根据理想化的数值模拟发现的。引入了一个特殊的参数来测量绝对角动量和熵面的一致程度。利用理想化系综轴对称数值模拟的结果对新的IR方程进行了评估。结果表明，新的红外方程能较好地再现模拟热带气旋强度的时间演变过程。新的IR方程表明，IR对TC强度和相应的最大位势强度(MPI)都有很强的依赖性。一个新的发现是，对于任何给定的相对强度，TC IR都依赖于MPI与近地面风速的平方。新IR方程的一些数值积分的结果也表明了TC成因的有限振幅性质。此外，新的红外理论也得到了基于北大西洋和北太平洋东部和西部最佳路径热带气旋资料的初步结果的支持。与现有的热带气旋增强随时间变化的理论相比，新的红外辐射方程能够在观测到的弱强度阶段提供真实的强度相关红外辐射。
In this study, the boundary layer tangential wind budget equation following the radius of maximum wind,.together with an assumed thermodynamical quasi-equilibrium boundary layer, is used to derive a new equation for tropical.cyclone (TC) intensification rate (IR). A TC is assumed to be axisymmetric in thermal-wind balance, with eyewall convection.coming into moist slantwise neutrality in the free atmosphere above the boundary layer as the storm intensifies, as.found recently based on idealized numerical simulations. An ad hoc parameter is introduced to measure the degree of.congruence of the absolute angular momentum and the entropy surfaces. The new IR equation is evaluated using results.from idealized ensemble full-physics axisymmetric numerical simulations. Results show that the new IR equation can.reproduce the time evolution of the simulated TC intensity. The new IR equation indicates a strong dependence of IR on.both TC intensity and the corresponding maximum potential intensity (MPI).A new finding is the dependence of TC IR on.the square of the MPI in terms of the near-surface wind speed for any given relative intensity. Results from some numerical.integrations of the new IR equation also suggest the finite-amplitude nature of TC genesis. In addition, the new IR theory is.also supported by some preliminary results based on best-track TC data over the North Atlantic Ocean and eastern and.western North Pacific Ocean. As compared with the available time-dependent theories of TC intensification, the new IR.equation can provide a realistic intensity-dependent IR during weak intensity stage as seen in observations.