An idealized, three‐dimensional, 1 km horizontal grid spacing numerical simulation of a rapidly intensifying tropical cyclone is used to extend basic knowledge on the role of mean and eddy momentum transfer on the dynamics of the intensification process. Examination of terms in the tangential and radial velocity tendency equations provides an improved quantitative understanding of the dynamics of the spin‐up process within the inner‐core boundary layer and eyewall regions of the system‐scale vortex. Unbalanced and non‐axisymmetric processes are prominent features of the rapid spin‐up process. In particular, the wind asymmetries, associated in part with the asymmetric deep convection, make a substantive contribution (∼30%) to the maximum wind speed inside the radius of this maximum. The analysis provides a novel explanation for inflow jets sandwiching the upper‐tropospheric outflow layer which are frequently found in numerical model simulations. In addition, it provides an opportunity to assess the applicability of generalized Ekman balance during rapid vortex spin‐up. The maximum tangential wind occurs within and near the top of the frictional inflow layer and as much as 10 km inside the maximum gradient wind. Spin‐up in the friction layer is accompanied by supergradient winds that exceed the gradient wind by up to 20%. Overall, the results affirm prior work pointing to significant limitations of a purely axisymmetric balance description, for example, gradient balance/Ekman balance, when applied to a rapidly intensifying tropical cyclone.

中文翻译：

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平均和涡动过程对热带气旋强度的贡献

一个理想的，3 km，1 km的水平网格间距数值模拟，用于快速增强的热带气旋，用于扩展关于平均和涡动量传递对增强过程动力学的作用的基础知识。切线和径向速度趋势方程中的项的检查提供了对系统尺度涡旋的内核边界层和眼墙区域内自旋过程动力学的定量理解。非平衡和非轴对称过程是快速旋转过程的显着特征。尤其是部分与不对称的深对流有关的风的不对称性做出了实质性贡献（〜30％）到此最大半径内的最大风速。该分析为数值模型模拟中经常发现的将对流层上流层夹在中间的射流提供了新颖的解释。此外，它还提供了一个机会，可以评估快速涡旋加速过程中广义埃克曼平衡的适用性。最大切向风发生在摩擦流入层的顶部之内和附近，并且在最大梯度风内部长达10 km。摩擦层中的自旋伴随着超梯度风，比梯度风高20％。总体而言，该结果证实了先前的工作，指出了当应用于快速加剧的热带气旋时，纯粹的轴对称平衡描述存在明显的局限性，例如，梯度平衡/埃克曼平衡。