How much does the upward advection of supergradient component of boundary-layer wind contribute to tropical cyclone intensification and maximum intensity?
How much does the upward advection of supergradient component of boundary-layer wind contribute to tropical cyclone intensification and maximum intensity?
复制标题
边界层风超梯度分量的向上平流对热带气旋增强和最大强度的贡献有多大？
DOI：
10.1175/jas-d-19-0350.1
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发表时间：
2020
期刊：
影响因子：
--
通讯作者：
Y.-L. Lin
中科院分区：
文献类型：
--
作者：
Li Y.-L.;Y. Wang;Y.-L. Lin
虽然超梯度风的发展已被充分理解，但超梯度风在热带气旋（TC）增强中的重要性仍存在争议。一种观点认为，风眼壁的旋转是由边界层的超梯度风引起的高切向动量的向上平流引起的。另一种观点认为，眼壁上升气流导致的超梯度风的向上平流导致向外的梯度力，导致在流入边界层上方形成浅的流出层。因此，由边界层的超梯度风的向上平流引起的眼壁切向风的自旋上升在很大程度上被由梯度力引起的外流引起的切向风的自旋下降所抵消。在这项研究中，净贡献的向上平流的超梯度风分量从边界层的强化率和TC的最终强度的量化通过集合敏感性数值试验使用轴对称TC模式。结果表明，与上述第二种观点一致，眼壁上升气流引起的边界层超梯度风分量的正向上平流，在很大程度上被向外凝聚力引起的外流引起的负径向平流所抵消。结果表明，高梯度风分量的上升平流对TC的增强率贡献很小（通常小于4%），但由于增强了内核海气热力不平衡，对最终强度的贡献约为10%~ 15%。
Although the development of supergradient winds is well understood, the importance of supergradient winds in tropical cyclone (TC) intensification is still under debate. One view is that the spinup of the eyewall occurs by the upward advection of high tangential momentum associated with supergradient winds from the boundary layer. The other view argues that the upward advection of supergradient winds by eyewall updrafts results in an outward agradient force, leading to the formation of a shallow outflow layer immediately above the inflow boundary layer. As a result, the spinup of tangential wind in the eyewall by the upward advection of supergradient wind from the boundary layer is largely offset by the spindown of tangential wind due to the outflow resulting from the agradient force. In this study, the net contribution by the upward advection of the supergradient wind component from the boundary layer to the intensification rate and final intensity of a TC are quantified through ensemble sensitivity numerical experiments using an axisymmetric TC model. Results show that consistent with the second view above, the positive upward advection of the supergradient wind component from the boundary layer by eyewall updrafts is largely offset by the negative radial advection due to the outflow resulting from the outward agradient force. As a result, the upward advection of the supergradient wind component contributes little (often less than 4%) to the intensification rate and but it contributes about 10%–15% to the final intensity of the simulated TC due to the enhanced inner-core air–sea thermodynamic disequilibrium.