Trapping of the near-inertial wave wakes of two consecutive hurricanes in the Loop Current
Trapping of the near-inertial wave wakes of two consecutive hurricanes in the Loop Current
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DOI：
10.1002/2015jc011592
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发表时间：
2016-09
影响因子：
--
通讯作者：
E. Pallàs‐Sanz;J. Candela;J. Sheinbaum;J. Ochoa;J. Jouanno
中科院分区：
文献类型：
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作者：
E. Pallàs‐Sanz;J. Candela;J. Sheinbaum;J. Ochoa;J. Jouanno
利用三角形系泊阵列的观测结果，描述了两个连续飓风古斯塔夫和艾克（2008年）在环流底部对波浪尾流的近惯性捕获。飓风古斯塔夫穿越环流的速度是飓风艾克的两倍，导致风力强度峰值更尖锐，但同样强大。在古斯塔夫过境后，主温跃层的近惯性振荡具有大的水平（340±45 km）和垂直（850 m）尺度。波动能以每天几十米的垂直群速度向下传播，导致[1.82-7.10]×10−3 W m− 2的向下能量通量。观测表明，600 m高空的多普勒频移和环流内垂直变化的涡度驱动了飓风产生的波尾的弥散。近惯性动能的增强和近惯性振荡的圆极化在一个关键层的基础上的环电流的群速度矢量是近水平的。利用原始方程数值模式研究了连续两次飓风近惯性波尾迹的捕获和放大。数值计算结果表明，由于波-平均流和波-波相互作用，在临界层附近，近惯性动能和垂直切变增加了10.2倍。这些相互作用的K剖面参数化导致在临界Richardson数Ric = 1时，湍流动能耗散率升高的带状区域为e [0.5-6.6]×10−6 W m−3，这取决于水柱的分层。本文受版权保护。All rights reserved.
The near-inertial trapping of the wave wakes of two consecutive hurricanes, Gustav and Ike (2008), at the base of the Loop Current is described using observations of a triangular mooring array. Hurricane Gustav translates over the Loop Current twice as fast and leads to a sharper, but equally strong, wind intensity peak than Hurricane Ike. Following the passage of Gustav, near-inertial oscillations in the main thermocline have large horizontal (∼340±45 km) and vertical (∼850 m) scales. The wave kinetic energy propagates down with a vertical group velocity of several tens of meters per day and leads to a downward energy flux of [1.82-7.10]×10−3 W m−2.Observations suggest that the dispersion of the wave wakes produced by the hurricanes is driven by Doppler shifting in the upper ∼600 m and the vertical-varying vorticity inside the Loop Current. Near-inertial kinetic energy is enhanced and near-inertial oscillations are circularly polarized in a critical layer at the base of the Loop Current where the group velocity vector is nearly horizontal. The trapping and amplification of the near-inertial wave wakes of two consecutive hurricanes is addressed using a primitive equation numerical model. Numerical results suggest an increase of the near-inertial kinetic energy and vertical shear by a factor of ∼2 near the critical layer due to wave-mean flow and wave-wave interactions. A K-Profile parameterization of these interactions results in banded regions of elevated turbulent kinetic energy dissipation rates of e ϵ [0.5-6.6]×10−6 W m−3 for critical Richardson number Ric = 1, depending on the stratification of the water column. This article is protected by copyright. All rights reserved.