We revisit the linear boundary‐layer approximation that expresses a generalized Ekman balance and use it to clarify a range of interpretations in the previous literature on the tropical cyclone boundary layer. Some of these interpretations relate to the reasons for inflow in the boundary layer and others relate to the presumed effects of inertial stability on boundary‐layer dynamics. Inertial stability has been invoked, for example, to explain aspects of boundary‐layer behaviour, including the frontogenetic nature of the boundary layer and its relationship to vortex spin‐up. Our analysis exposes the fallacy of invoking inertial stability as a resistance to radial inflow in the boundary layer. The analysis shows also that the nonlinear acceleration terms become comparable to the linear Coriolis acceleration terms in relatively narrow vortices that are inertially stable above the boundary layer. Estimates of the nonlinear accelerations using the linear solutions are expected to underestimate the actual contribution in a nonlinear boundary‐layer model, cautioning against neglecting the nonlinear terms in diagnostic or prognostic models.

中文翻译：

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再谈热带气旋边界层的广义Ekman模型：惯性稳定作为恢复力的神话

我们重新研究了表示广义埃克曼平衡的线性边界层近似，并用它来阐明以前文献中关于热带气旋边界层的一系列解释。这些解释中的一些与边界层流入的原因有关，另一些与惯性稳定性对边界层动力学的假定影响有关。例如，惯性稳定性已被用来解释边界层行为的各个方面，包括边界层的前生性质及其与涡旋旋转的关系。我们的分析揭示了调用惯性稳定性的谬误，因为它是对边界层中径向流入的抵抗。分析还显示，在边界层上方惯性稳定的相对较窄的涡流中，非线性加速度项变得与线性科里奥利加速度项可比。使用线性解估计非线性加速度预计会低估非线性边界层模型中的实际贡献，因此请注意不要忽略诊断或预后模型中的非线性项。