Estimating Internal Wave Energy Fluxes in the Ocean

2005 ◽  
Vol 22 (10) ◽  
pp. 1551-1570 ◽  
Author(s):  
Jonathan D. Nash ◽  
Matthew H. Alford ◽  
Eric Kunze
Keyword(s):  
Internal Wave ◽  
Energy Flux ◽  
Wave Energy ◽  
Energy Fluxes ◽  
Near Surface ◽  
Data Limitations ◽  
Pressure Anomaly ◽  
Internal Wave Generation ◽  
Hydrostatic Balance ◽  
Wave Induced

Abstract Energy flux is a fundamental quantity for understanding internal wave generation, propagation, and dissipation. In this paper, the estimation of internal wave energy fluxes 〈u′p′〉 from ocean observations that may be sparse in either time or depth are considered. Sampling must be sufficient in depth to allow for the estimation of the internal wave–induced pressure anomaly p′ using the hydrostatic balance, and sufficient in time to allow for phase averaging. Data limitations that are considered include profile time series with coarse temporal or vertical sampling, profiles missing near-surface or near-bottom information, moorings with sparse vertical sampling, and horizontal surveys with no coherent resampling in time. Methodologies, interpretation, and errors are described. For the specific case of the semidiurnal energy flux radiating from the Hawaiian ridge, errors of ∼10% are typical for estimates from six full-depth profiles spanning 15 h.

Near-Surface Frontal Zone Trapping and Deep Upward Propagation of Internal Wave Energy in the Japan/East Sea

2003 ◽  
Vol 33 (4) ◽  
pp. 900-912 ◽  
Author(s):  
Andrey Y. Shcherbina ◽  
Lynne D. Talley ◽  
Eric Firing ◽  
Peter Hacker
Keyword(s):  
Internal Wave ◽  
Wave Energy ◽  
Frontal Zone ◽  
East Sea ◽  
Near Surface

scholarly journals Vertical mixing and internal wave energy fluxes in a sill fjord

2016 ◽  
Vol 159 ◽  
pp. 15-32 ◽  
Author(s):  
André Staalstrøm ◽  
Lars Petter Røed
Keyword(s):  
Internal Wave ◽  
Wave Energy ◽  
Vertical Mixing ◽  
Energy Fluxes

Diapycnal diffusivity induced by the breaking of lee waves

2020 ◽  
Author(s):  
Thomas Eriksen ◽  
Carsten Eden ◽  
Dirk Olbers
Keyword(s):  
Internal Wave ◽  
Internal Waves ◽  
Energy Flux ◽  
Wave Energy ◽  
Diapycnal Mixing ◽  
Overturning Circulation ◽  
Lee Waves ◽  
Lee Wave ◽  
Wave Energy Flux ◽  
Diapycnal Diffusivity

<p>A key component in setting the large scale ocean circulation is the process of diapycnal mixing, since this can drive the meridional overturning circulation. Diapycnal mixing in the interior ocean is predominantly associated with the breaking of internal waves. Traditionally, diapycnal mixing has been represented in ocean models by a diapycnal diffusivity either constant or exponentially decreasing with depth. This approach, however, does not take into account the actual physics behind the breaking of internal waves. The energetically consistent internal wave model IDEMIX (Internal wave Dissipation, Energetics and MIXing), on the other hand, computes diffusivities directly on the basis of internal wave energetics. One such type of internal waves are lee waves. These are generated and subsequently dissipated when geostrophic currents interact with bottom topography and are therefore believed to be a source of energy for deep ocean mixing. In this study IDEMIX is coupled to a 1/12<sup>th</sup> degree regional model of the Atlantic. The lee wave energy flux is calculated and used as a bottom flux at each time step effectively allowing lee waves to propagate, interact with mean flow and waves, and subsequently dissipate. This setup enables not only an estimate of the lee wave energy flux but also a direct investigation of the influence of lee waves on dissipation, stratification and horizontal and overturning circulation.</p>

scholarly journals Strong Internal Waves Generated by the Interaction of the Kuroshio and Tides over a Shallow Ridge

2019 ◽  
Vol 49 (11) ◽  
pp. 2917-2934 ◽  
Author(s):  
Eiji Masunaga ◽  
Yusuke Uchiyama ◽  
Hidekatsu Yamazaki
Keyword(s):  
Internal Wave ◽  
Internal Waves ◽  
Energy Flux ◽  
Wave Energy ◽  
High Frequency ◽  
Deep Ocean ◽  
Internal Tides ◽  
Navier Stokes ◽  
Wave Energy Flux ◽  
The Kuroshio

AbstractThe Kuroshio and tides significantly influence the oceanic environment off the Japanese mainland and promote mass/heat transport. However, the interaction between the Kuroshio and tides/internal waves has not been examined in previous works. To investigate this phenomenon, the two-dimensional high-resolution nonhydrostatic oceanic Stanford Unstructured Nonhydrostatic Terrain-Following Adaptive Navier–Stokes Simulator (SUNTANS) model was employed. The results show that strong internal tides propagating upstream in the Kuroshio are generated at a near-critical internal Froude number (Fri = 0.91). The upstream internal wave energy flux reaches a magnitude of 12 kW m−1, which is approximately 3 times higher than that of internal waves without the Kuroshio. On the other hand, under supercritical conditions, the Kuroshio suppresses the internal wave energy flux. The interaction of internal tides and the Kuroshio also generates upstream propagating high-frequency internal waves and solitary wave packets. The high-frequency internal waves contribute to the increase in the total internal wave energy flux up to 40% at the near-critical Fri value. The results of this study suggest that the interaction of internal tides and the Kuroshio enhances the upstream propagating internal tides under the specified conditions (Fri ~ 1), which may lead to deep ocean mixing and transport at significant distances from the internal wave generation sites.

scholarly journals Internal wave energy flux from density perturbations in nonlinear stratifications

2018 ◽  
Vol 856 ◽  
pp. 898-920 ◽  
Author(s):  
Frank M. Lee ◽  
Michael R. Allshouse ◽  
Harry L. Swinney ◽  
Philip J. Morrison
Keyword(s):  
Internal Wave ◽  
Energy Flux ◽  
Wave Energy ◽  
Density Perturbation ◽  
Computational Method ◽  
Buoyancy Frequency ◽  
Pressure Perturbation ◽  
Perturbation Field ◽  
Wave Energy Flux ◽  
Instantaneous Energy

Internal gravity wave energy contributes significantly to the energy budget of the oceans, affecting mixing and the thermohaline circulation. Hence it is important to determine the internal wave energy flux $\boldsymbol{J}=p\,\boldsymbol{v}$, where $p$ is the pressure perturbation field and $\boldsymbol{v}$ is the velocity perturbation field. However, the pressure perturbation field is not directly accessible in laboratory or field observations. Previously, a Green’s function based method was developed to calculate the instantaneous energy flux field from a measured density perturbation field $\unicode[STIX]{x1D70C}(x,z,t)$, given a constant buoyancy frequency $N$. Here we present methods for computing the instantaneous energy flux $\boldsymbol{J}(x,z,t)$ for an internal wave field with vertically varying background $N(z)$, as in the oceans where $N(z)$ typically decreases by two orders of magnitude from the pycnocline to the deep ocean. Analytic methods are presented for computing $\boldsymbol{J}(x,z,t)$ from a density perturbation field for $N(z)$ varying linearly with $z$ and for $N^{2}(z)$ varying as $\tanh (z)$. To generalize this approach to arbitrary $N(z)$, we present a computational method for obtaining $\boldsymbol{J}(x,z,t)$. The results for $\boldsymbol{J}(x,z,t)$ for the different cases agree well with results from direct numerical simulations of the Navier–Stokes equations. Our computational method can be applied to any density perturbation data using the MATLAB graphical user interface ‘EnergyFlux’.

Non-hydrostatic and non-linear contributions to the internal wave energy flux in sill regions

2009 ◽  
Vol 59 (6) ◽  
pp. 881-897 ◽  
Author(s):  
Alan M. Davies ◽  
Jiuxing Xing ◽  
Jarle Berntsen
Keyword(s):  
Internal Wave ◽  
Energy Flux ◽  
Wave Energy ◽  
Non Linear ◽  
Wave Energy Flux

scholarly journals Internal Wave Reflection on Shelf Slopes with Depth-Varying Stratification

2013 ◽  
Vol 43 (2) ◽  
pp. 248-258 ◽  
Author(s):  
Rob A. Hall ◽  
John M. Huthnance ◽  
Richard G. Williams
Keyword(s):  
Internal Wave ◽  
Internal Waves ◽  
Energy Flux ◽  
Internal Tide ◽  
Shelf Break ◽  
Maximum Slope ◽  
Near Surface ◽  
Shelf Slope ◽  
Linear Slope ◽  
Horizontal Wavelength

Abstract Reflection of internal waves from sloping topography is simple to predict for uniform stratification and linear slope gradients. However, depth-varying stratification presents the complication that regions of the slope may be subcritical and other regions supercritical. Here, a numerical model is used to simulate a mode-1, M2 internal tide approaching a shelf slope with both uniform and depth-varying stratifications. The fractions of incident internal wave energy reflected back offshore and transmitted onto the shelf are diagnosed by calculating the energy flux at the base of slope (with and without topography) and at the shelf break. For the stratifications/topographies considered in this study, the fraction of energy reflected for a given slope criticality is similar for both uniform and depth-varying stratifications. This suggests the fraction reflected is dependent only on maximum slope criticality and independent of the depth of the pycnocline. The majority of the reflected energy flux is in mode 1, with only minor contributions from higher modes due to topographic scattering. The fraction of energy transmitted is dependent on the depth-structure of the stratification and cannot be predicted from maximum slope criticality. If near-surface stratification is weak, transmitted internal waves may not reach the shelf break because of decreased horizontal wavelength and group velocity.

scholarly journals Dependence of the internal wave energy flux on the parameters of a two­layer hydrodynamic system

2020 ◽  
Vol 4 (8 (106)) ◽  
pp. 28-36
Author(s):  
Volodymyr Naradovyi ◽  
Yurii Hurtovyi ◽  
Olga Avramenko
Keyword(s):  
Internal Wave ◽  
Energy Flux ◽  
Wave Energy ◽  
Hydrodynamic System ◽  
Wave Energy Flux

scholarly journals Observations of Tidal Internal Wave Beams at Kauai Channel, Hawaii

2009 ◽  
Vol 39 (2) ◽  
pp. 421-436 ◽  
Author(s):  
S. T. Cole ◽  
D. L. Rudnick ◽  
B. A. Hodges ◽  
J. P. Martin
Keyword(s):  
Internal Wave ◽  
Energy Flux ◽  
Momentum Flux ◽  
Internal Tides ◽  
Turbulent Dissipation ◽  
Ridge Structure ◽  
Almost Everywhere ◽  
Hawaiian Ridge ◽  
Internal Wave Generation ◽  
Almost All

Abstract To observe the across-ridge structure of internal tides, density and velocity were measured using SeaSoar and a Doppler sonar over the upper 400–600 m of the ocean extending 152 km on each side of the Hawaiian Ridge at Kauai Channel. Eighteen sections were completed in about 18 days with sampling intentionally detuned from the lunar semidiurnal (M2) tide so that averaging over all sections was equivalent to phase averaging the M2 tide. Velocity and displacement variance and several covariances involving velocity and displacement showed one M2 internal wave beam on each side of the ridge and reflection of the beams off of the surface. Theoretical ray slopes aligned with the observed beams and originated from the sides of the ridge. Energy flux was in agreement with internal wave generation at the ridge. Inferred turbulent dissipation was elevated relative to open ocean values near tidal beams. Energy flux was larger than total dissipation almost everywhere across the ridge. Internal wave energy flux and dissipation at Kauai Channel were 1.5–2.5 times greater than at the average location along the Hawaiian Ridge. The upper 400–600 m was about 1/3 to 1/2 as energetic as the full-depth ocean. Tidal beams interact with each other over the entire length of the beams causing gradients along beams in almost all covariances, momentum flux divergences, and mean flows. At Kauai Channel, momentum flux divergences corresponded to mean flows of 1–4 cm s−1.

Internal Wave Generation in Tropical Upwelling Regions: the Angolan and Peruvian Shelves

2020 ◽  
Author(s):  
Kevin Lamb ◽  
Peter Brandt ◽  
Marcus Dengler
Keyword(s):  
Internal Wave ◽  
Solitary Waves ◽  
High Frequency ◽  
Wave Generation ◽  
Internal Solitary Waves ◽  
Small Scale ◽  
Tropical Atlantic ◽  
Near Surface ◽  
High Productivity ◽  
Internal Wave Generation

<p>The Angolan and Peruvian shelves are located in upwelling regions along the eastern boundaries of the tropical Atlantic and Pacific Oceans. They are sites of important fisheries supported by high productivity which is driven by fluxes of nutrients from deep to near surface water along the coast. Mixing associated with internal waves is believed to play a role in this process. Recent field observations have shown the presence of an active internal wave field that includes internal solitary waves. In this talk results of high-resolution two-dimensional simulations of internal wave generation by tide-topography interactions on the Angolan and Peruvian shelves are presented. The simulations show the generation of internal wave beams at near-critical slopes and the generation of high-frequency internal solitary waves. The high-frequency IW spectrum is enhanced when small scale bathymetric ripples are included. Wave generation during winter and summer stratifications will be compared.</p>

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