The Influence of Oceanic Barrier Layers on Tropical Cyclone Intensity as Determined through Idealized, Coupled Numerical Simulations
The Influence of Oceanic Barrier Layers on Tropical Cyclone Intensity as Determined through Idealized, Coupled Numerical Simulations
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DOI：
10.1175/jpo-d-18-0267.1
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发表时间：
2019-07
影响因子：
3.5
通讯作者：
J. Hlywiak;D. Nolan
中科院分区：
文献类型：
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作者：
J. Hlywiak;D. Nolan
本文研究了海洋屏障层形式的上层盐度分层与热带气旋(TC)加强之间的联系。关于海洋盐度是否是影响热带气旋增强的一个可以忽略的因素，前人的工作存在分歧。在许多这些研究中得出的关系是基于观测的，观测可以是稀疏的或不完整的，或者是不耦合的模型，忽略了海-气反馈。在这里，使用天气研究和预报(WRF)模式与3D Price-Weller-Pinkel(PWP)海洋模式耦合进行的TCS的理想化集合模拟有助于在受控的、高分辨率的中尺度环境中检查TC-上层海洋系统。理想化的垂直海洋剖面是根据亚马逊-奥里诺科河羽流区域的障碍层剖面模拟的，其中障碍层被定义为混合层和等温层深度之间的垂直盐度梯度。我们的结果表明，对于1类飓风强度或更大的热带气旋，当整个集合成员平均时，厚(24-30米)的障碍层可能有利于进一步加强6%-15%。相反，较弱的气旋会被厚厚的障碍层阻挡。热带气旋内核以下的海面温度降低是造成进一步加强的主要原因。结果对风暴平移速度、初始海洋混合层温度和大气垂直风切变的敏感性测试提供了更全面的分析。最后，结果表明，当使用3D或1D版本的PWP时，集合平均强度的结果是相似的。
The connection relating upper-ocean salinity stratification in the form of oceanic barrier layers to tropical cyclone (TC) intensification is investigated in this study. Previous works disagree on whether ocean salinity is a negligible factor on TC intensification. Relationships derived in many of these studies are based on observations, which can be sparse or incomplete, or uncoupled models, which neglect air–sea feedbacks. Here, idealized ensemble simulations of TCs performed using the Weather Research and Forecasting (WRF) Model coupled to the 3D Price–Weller–Pinkel (PWP) ocean model facilitate examination of the TC–upper-ocean system in a controlled, high-resolution, mesoscale environment. Idealized vertical ocean profiles are modeled after barrier layer profiles of the Amazon–Orinoco river plume region, where barrier layers are defined as vertical salinity gradients between the mixed and isothermal layer depths. Our results reveal that for TCs of category 1 hurricane strength or greater, thick (24–30 m) barrier layers may favor further intensification by 6%–15% when averaging across ensemble members. Conversely, weaker cyclones are hindered by thick barrier layers. Reduced sea surface temperature cooling below the TC inner core is the primary reason for additional intensification. Sensitivity tests of the results to storm translation speed, initial oceanic mixed layer temperature, and atmospheric vertical wind shear provide a more comprehensive analysis. Last, it is shown that the ensemble mean intensity results are similar when using a 3D or 1D version of PWP.