Understanding the rapid intensification (RI) of Hurricane Wilma (2005) in terms of the maximum wind has been carried out in a series of papers, this study examines the gradient wind balance and imbalance during RI, based on a 72-h Wilma prediction conducted using the Weather Research Forecast Model (WRF) with the 1-km grid resolution. Results show that the pressure gradient force (PGF) near the eyewall increases rapidly during the RI period. The maximum PGF associated with the gradient wind balance is determined by the strong radial gradient of the thermal field near the eyewall, resulting from the warming in the eye and adiabatic cooling near the eyewall. The maximum PGF occurs inside the radius of the maximum wind, causing a convergence region and intense updrafts, which favors RI. In a balanced symmetric framework, the hydrostatic PGF accounts for a major fraction (70 %–90 %) of the predicted PGF, and the secondary circulation is underestimated by the Sawyer-Eliassen equation within the boundary layer, at upper levels and through the intense eyewall updrafts where gradient wind imbalance occurs. The unbalanced force accelerates the boundary-layer radial inflow that contributes to the inward contraction of the eyewall and then enhances the radially inward advection of high absolute angular momentum. The eyewall convection strengthens where the boundary-layer inflows, convergence, and heat and moisture flux are collocated. With the high inertial stability, a sufficient conversion efficiency from energy to kinematic energy favors the RI of Wilma.

中文翻译：

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飓风威尔玛快速增强过程中的梯度风平衡分析 （2005）


在一系列论文中已经根据最大风力了解了飓风威尔玛 （2005） 的快速增强 （RI），本研究基于使用天气研究预报模型 （WRF） 进行的 72 小时威尔玛预测，以 1 公里网格分辨率进行研究，研究了 RI 期间的梯度风平衡和不平衡。结果表明，在 RI 期间，眼壁附近的压力梯度力 （PGF） 迅速增加。与梯度风平衡相关的最大 PGF 由眼壁附近热场的强径向梯度决定，这是由眼中的升温和眼壁附近的绝热冷却引起的。最大 PGF 发生在最大风的半径内，导致会聚区和强烈的上升气流，这有利于 RI。在平衡对称框架中，静水 PGF 占预测 PGF 的主要部分 （70 %–90 %），并且次级环流被边界层内的 Sawyer-Eliassen 方程低估，在上层和通过发生梯度风不平衡的强烈眼壁上升气流。不平衡力加速了边界层径向流入，这有助于眼壁的向内收缩，然后增强了高绝对角动量的径向向内平流。眼壁对流在边界层流入、会聚以及热湿通量并置的地方加强。由于惯性稳定性高，从能量到运动能的足够转换效率有利于 Wilma 的 RI。