On the concentration of near-inertial waves in anticyclones

Danioux, Eric; Vanneste, Jacques; Bühler, Oliver

doi:10.1017/jfm.2015.252

Cited by 46 publications

(62 citation statements)

References 17 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…Regions with negative relative vorticity,

ζ ((), = \frac{true}{\partial v} - \frac{true}{\partial u}) < 0

, can trap NIWs and enhance downward radiation of NIW energy (Danioux et al, ; Kunze, ; Lee & Niiler, ; Park et al, ; Park & Watts, ; Young & Jelloul, ; Zhai et al, ). The high‐NIW‐energy patches in the deep layer are coincident with negative ζ regions in the upper layer (Figure ).…”

Section: Resultsmentioning

confidence: 99%

“…Background currents can redistribute NIW energy (Alford, ; Garrett, ; Kunze, ) through advection, or by forming regions of negative relative vorticities, which facilitate trapping and draining of the energy (Danioux et al, ; Kunze, ; Lee & Niiler, ; Young & Jelloul, ; Zhai et al, ). Such trapped NIWs in a negative relative vorticity region were observed in the Ulleung Basin located in the southwestern EJS (Byun et al, ; Park & Watts, ).…”

Section: Introductionmentioning

confidence: 99%

See 1 more Smart Citation

Temporal and Spatial Variability of Near‐Inertial Waves in the East/Japan Sea From a High‐Resolution Wind‐Forced Ocean Model

Jeon

Park

2019

JGR Oceans

View full text Add to dashboard Cite

Near‐inertial waves (NIWs), a fundamental oceanic response to wind forcing, play an important role in dynamical processes related to ocean mixing and hence have attracted sustained interest. Herein, we investigate temporally and spatially varying NIW distributions in the mixed and deep layers of the East/Japan Sea (EJS) using high‐resolution hourly‐wind‐forced data‐assimilated ocean model outputs. Temporally, the kinetic energy of NIWs in the mixed and deep layers is higher in fall and winter than in spring and summer, showing maxima in December, corresponding to wind forcings of both wind stress and wind‐current resonance. Spatially, the NIW energy in the mixed layer is higher on the northern side of the subpolar front (SPF), although there are no significant spatial differences in the wind forcings. Because of intensive background currents and their vorticities in the upper layer on the southern side of the SPF, vertical transfer of NIW energy is facilitated, shown by a shorter e‐folding decay time scale of NIWs in the mixed layer on the southern side of the SPF. The NIW kinetic energy in the deep layer of 400–1,000 m is higher on the southern side than on the northern side, an opposite spatial pattern to that in the mixed layer, but consistent with a previous observational study. Our results confirm that energetic anticyclonic circulations with negative relative vorticity in the upper layer on the southern side enable vertical penetration of NIW energy from the mixed layer to the deep layer more effectively.

show abstract

“…Regions with negative relative vorticity,

ζ ((), = \frac{true}{\partial v} - \frac{true}{\partial u}) < 0

Section: Resultsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Temporal and Spatial Variability of Near‐Inertial Waves in the East/Japan Sea From a High‐Resolution Wind‐Forced Ocean Model

Jeon

Park

2019

JGR Oceans

View full text Add to dashboard Cite

show abstract

“…During the first few days, however, ζ -refraction leads to a collapse of the wave scales onto that of the vorticity field (Klein et al 2004). Wave energy then fluxes into anticyclonic regions (Danioux et al 2015). Anticyclones thereafter act as wave drains, guiding wave energy and shear downwards into the ocean interior (Lee and Niiler 1998), perhaps leading to mixing (Kunze et al 1995).…”

Section: Discussionmentioning

confidence: 99%

“…This attraction of wave energy into anticyclonic regions, and repulsion from cyclonic regions, is a wellknown phenomenon, occurring both in realistic primitiveequation models ) and observations (Elipot et al 2010). Explanations have been proposed relying on the broadening of the allowable frequency band in negative vorticity regions and subsequent trapping of rays (Kunze 1985), appeals to the quantum analogy between energy wells and negative vorticity (Balmforth et al 1998), and more recently, a conservation law of the YBJ model that applies to near-inertial waves in a steady flows (Danioux et al 2015).…”

Section: Wave Propagationmentioning

confidence: 99%

Penetration of Wind-Generated Near-Inertial Waves into a Turbulent Ocean

Asselin

Young

2020

Journal of Physical Oceanography

View full text Add to dashboard Cite

An idealized storm scenario is examined in which a wind-generated inertial wave interacts with a turbulent baroclinic quasi-geostrophic flow. The flow is initialized by spinning up a Eady model with a realistic stratification profile. The storm is modeled as an initial value problem for a mixed-layer confined, horizontallyuniform inertial oscillation. The primordial inertial oscillation then evolves under the effects of advection, refraction, dispersion and dissipation. Waves feedback onto the flow by modifying its potential vorticity. In the first few days, refraction dominates and wave energy is attracted (repelled) by regions of negative (positive) vorticity. Wave energy is subsequently drained down anticyclonic pipes. This drainage halts as wave energy encounters weakening vorticity. After a week or two, wave energy accumulates at the bottom of negative vorticity features, i.e. along filamentary structures at shallow depths and in larger anticyclones at greater depths. Wave feedback tends to weaken vortices and thus slow down wave penetration. This effect, however, is found to be weak even for vigorous storms.

show abstract

“…Following the above theoretical approaches, several numerical process‐oriented studies have been conducted to investigate the trapping of NIWs by mesoscale eddies (e.g., Danioux et al, ; Danioux & Klein, ; Joyce et al, ; Lee & Niiler, ; Zhai et al, , ). Their results support the theoretical predictions showing that mesoscale anticyclonic eddy fields drain near‐inertial energy from the ocean surface to the deep layers.…”

Section: Introductionmentioning

confidence: 99%

Near‐Inertial Wave Trapping Near the Base of an Anticyclonic Mesoscale Eddy Under Normal Atmospheric Conditions

et al. 2019

View full text Add to dashboard Cite

Observational evidence demonstrates the signature of near-inertial wave (NIW) trapping by a long-lived westward propagating mesoscale anticyclonic eddy under normal atmospheric conditions. Cross-eddy sections of density and shipboard acoustic Doppler current profiler data show the downward (upward phase) propagation of NIW packets with vertical wavelengths of 200 m within the eddy, and wave energy amplification in a critical vertical layer located near the base of the anticyclone. Elevated strain variance, enhanced turbulent kinetic energy dissipation rates obtained from a fine-scale parameterization, and the occurrence of low (≤1) gradient Richardson numbers are consistent with turbulence production and mixing from 400 m to at least the maximum sampling depth of 725 m associated with the trapped NIWs. The observation of NIW packets near the eddy base at two different stages of the survey separated by 10 days and the persistence of low to moderate winds before and during the eddy sampling strongly suggest that our findings may be common in similar open-ocean anticyclonic eddies under normal wind conditions. Plain Language Summary Near-inertial waves-or internal gravity waves with a frequency near the inertial frequency-are typically excited at the sea surface by variable wind stress forcing. These waves can be trapped and amplified at the base of mesoscale (horizontal scales of about 10-100 km) anticyclonic eddies, especially after storms or strong wind events, situations in which high near-inertial energy is generated. In this article we present observational evidence of near-inertial wave trapping during low to moderate wind conditions. We also show that these trapped waves lead to deep mixing near the base of the eddy. The observation of near-inertial wave packets on two different dates and the low to moderate winds persistent during the survey suggest that our findings may be common in other similar open-ocean eddies. Mesoscale anticyclonic eddies of the World Ocean may therefore act as deep mixing structures as they propagate westward.

show abstract

On the concentration of near-inertial waves in anticyclones

Cited by 46 publications

References 17 publications

Temporal and Spatial Variability of Near‐Inertial Waves in the East/Japan Sea From a High‐Resolution Wind‐Forced Ocean Model

Temporal and Spatial Variability of Near‐Inertial Waves in the East/Japan Sea From a High‐Resolution Wind‐Forced Ocean Model

Penetration of Wind-Generated Near-Inertial Waves into a Turbulent Ocean

Near‐Inertial Wave Trapping Near the Base of an Anticyclonic Mesoscale Eddy Under Normal Atmospheric Conditions

Contact Info

Product

Resources

About