Damping of inertial motions through the radiation of near-inertial waves in a dipole vortex in the Iceland Basin

IF 2.8 2区地球科学 Q1 OCEANOGRAPHY

Journal of Physical Oceanography Pub Date : 2023-05-22 DOI:10.1175/jpo-d-22-0202.1

L. Thomas, E. Skyllingstad, L. Rainville, Verena Hormann, L. Centurioni, J. Moum, O. Asselin, Craig M. Lee

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引用次数: 1

Abstract

Along with boundary layer turbulence, downward radiation of near-inertial waves (NIWs) damps inertial oscillations (IOs) in the surface ocean, however the latter can also energize abyssal mixing. Here we present observations made from a dipole vortex in the Iceland Basin where, after the period of direct wind forcing, IOs lost over half their kinetic energy (KE) in two inertial periods to radiation of NIWs with minimal turbulent dissipation of KE. The dipole’s vorticity gradient led to a rapid reduction in the NIW’s lateral wavelength via ζ-refraction that was accompanied by isopycnal undulations below the surface mixed layer. Pressure anomalies associated with the undulations were correlated with the NIW’s velocity yielding an energy flux of 310 mW m−2 pointed antiparallel to the vorticity gradient and a downward flux of 1 mW m−2 capable of driving the observed drop in KE. The minimal role of turbulence in the energetics after the IOs had been generated by the winds was confirmed using a large eddy simulation driven by the observed winds.

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冰岛盆地偶极涡旋中近惯性波辐射对惯性运动的阻尼

与边界层湍流一起，近惯性波（NIW）的向下辐射阻尼了表层海洋中的惯性振荡（IO），然而后者也可以激发深海混合。在这里，我们介绍了从冰岛盆地的偶极子涡旋中进行的观测，在直接风力作用后，IOs在两个惯性周期内损失了超过一半的动能（KE），这是由于NIW的辐射，KE的湍流耗散最小。偶极子的涡度梯度通过ζ-折射导致NIW的横向波长迅速降低，并伴随着表面混合层下方的等密度波动。与波动相关的压力异常与NIW的速度相关，产生310 mW m−2的能量通量，指向与涡度梯度反平行的方向，以及1 mW m–2的向下通量，能够驱动观测到的KE下降。使用由观测到的风驱动的大涡模拟，证实了风产生IOs后湍流在能量学中的最小作用。

本文章由计算机程序翻译，如有差异，请以英文原文为准。

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来源期刊

Journal of Physical Oceanography 地学-海洋学

CiteScore

2.40

自引率

20.00%

发文量

200

审稿时长

4.5 months

期刊介绍： The Journal of Physical Oceanography (JPO) (ISSN: 0022-3670; eISSN: 1520-0485) publishes research related to the physics of the ocean and to processes operating at its boundaries. Observational, theoretical, and modeling studies are all welcome, especially those that focus on elucidating specific physical processes. Papers that investigate interactions with other components of the Earth system (e.g., ocean–atmosphere, physical–biological, and physical–chemical interactions) as well as studies of other fluid systems (e.g., lakes and laboratory tanks) are also invited, as long as their focus is on understanding the ocean or its role in the Earth system.