Internal waves Research Papers - Academia.edu (original) (raw)

2025

BONNETON, P., LEFEBVRE, J-P., BRETEL, P., OUILLON, S. and DOUILLET, P., 2007. Tidal modulation of wave-setup and wave-induced currents on the Aboré coral reef, New Caledonia. Journal of Coastal Research, SI 50 (Proceedings of the 9th International Coastal Symposium), 762 - 766. Gold Coast, Australia, ISSN 0749.0208 As waves break on a reef, they create a radiation stress gradient that drives wave-setup and wave-induced currents. In this paper, tidally modulated wave-induced current and wave-setup are presented and analysed from field measurements performed on the Aboré coral reef in the southwest lagoon of New Caledonia. We show, in agreement with analytical models by Symonds et al (1995) and Hearn (1999), that this tidally modulated wave circulation is mainly controlled by the difference between the depth at the breakpoint and the water depth over the reef. A specific calibration of these models is proposed for the Aboré reef.

2025, Journal of Marine Systems

During the Echolag cruise (13 February-8 March 2007), the effect of 16-30 knot trade winds on abundance, community structure and dynamics of phytoplankton was investigated in the southern part of the New Caledonian coral reefs and surrounding oceanic waters. In this area, the coral reefs form two horn-like structures (hereinafter referred to as 'horn reefs'), oriented south-east, and separated by a relatively deep valley. Three repeated samplings at one week intervals of a 32 station array showed that trade winds induce surface water cooling and significant enrichment of mid-and bottom waters above the reef shelf. This enrichment appeared as the result of a general rise of the oceanic thermocline and nitracline due to the combination of trade winds and tidally-generated internal waves between the horn reefs. It was accompanied by a factor of 1.5 and 2.3 mean increase for the chlorophyll concentration and picoplankton-nanoplankton cell number, respectively. From diel variations of in vivo chlorophyll a fluorescence and hourly sampling, phytoplankton gross growth rate was estimated to be 1-1.35 divisions per day and was quasi balanced with phytoplankton mortality for a 24 h period.

2025, Renewable Energy (Elsevier)

Tidal stream energy conversion is an attractive renewable energy option due to the predictability of tides and high energy density. Yet, before sites can be exploited to their full potential, detailed resource characterization is required to optimize device selection and array configuration, and to minimize environmental impacts. This study focuses on the Morlais tidal energy site in North Wales, where developers have been awarded 38 MW of tidal stream generation capacity by the UK Government. The study analyses sea bed and water column data collected across the site over the past decade, including multibeam echosounder data, multiple acoustic Doppler current profiler (ADCP) time series, meteorological and wave data. Additionally, high-resolution tidal and wave models are applied to further characterize the spatio-temporal variability. The undisturbed power density exceeds 10 kW∕m 2 at Morlais, with the most energetic locations closest to the shore-facilitating power export to the grid. There is significant interaction of waves and currents across the site. However, this mainly influences wave properties, which could affect maintenance of moorings or devices (due to increased wave steepness), rather than directly influencing the tidal energy resource. There are variations in flood/ebb asymmetry between ADCP moorings, and this is relatively strong at some locations.

2025

Remote sensing data reveals tidal impacts on chlorophyll-a (CHL) concentration in the Brazilian Equatorial Margin. In the northwest shelf, where the turbid Amazon River plume dominates, sediment resuspension by barotropic tides during spring tides or reduced currents in neap tides likely decrease primary production, shown by negative CHL differences (∼-55%) in spring-neap tide composites. The northeastern shelf, with clearer waters, shows positive CHL anomalies (∼32%) likely due to nutrient-rich vertical mixing from barotropic tides. Along internal tide (IT) pathways, elevated CHL bands (∼30% above average) align with IT crests. The CHL distribution in the spring-neap composite shows wave-like patterns, with positive CHL differences (∼2.2%) linked to IT crests. IT interactions with background currents cause the shifting of the location of incoherent IT throughout the year, partially disrupting the CHL signals in the spring-neap tide composites. A 1-2 day lag between higher CHL variability and tidal potential suggests delayed nutrient mixing post-spring-neap tides.

2025, OCEANS 2000 MTS/IEEE Conference and Exhibition. Conference Proceedings (Cat. No.00CH37158)

Source localization with a single sensor explores the time spread of the received signal as it travels from the emitter to the receiver. In shallow water, and for ranges larger than a few times the water depth, the received signal typically exhibits a large number of closely spaced arrivals. However, not all the arrivals are equally important for estimating the source position since a number of them convey redundant information. Theoreticaly, identifying the non-redundant arrivals is feasible in a isovelocity range independent waveguide. In previous work, the number of nonredundant arrivals and the dimension of the data sample signal subspace have been related in a range-independent case. This paper addresses the problem of determining the number of significant arrivals for localizing a sound source over a range-dependent environment off the West coast of Portugal during the INTIMATE'96 sea trial.

2025, Journal of Computational Acoustics

The problem of nonlinear interaction of solitary wave packets with acoustic signals has been intensively studied in recent years. A key goal is to explain the observed transmission loss of shallow-water propagating signals, which has been found to be strongly time-dependent, anisotropic, and sometimes exhibited unexpected attenuation versus frequency. Much of the existing literature considers the problem of signal attenuation in a static environment, without considering additional effects arising from groups of solitons evolving both in range and time. Hydrographic and acoustic data from the INTIMATE'96 experiment clearly exhibit the effects of soliton packets. However, in contrast with reported observations of signal attenuation, the observed transmission loss shows a pronounced signal enhancement that behaves like a focusing effect. This focusing is correlated with peaks in current, temperature, and surface tide. That correlation suggests that the nonlinear interaction of soli...

2025, Proceedings of Meetings on Acoustics

2025

The currents in the lowest few millinleters of the bottom boundary layer of lakes are highly important for the dissipation of kinetic energy and for chemical processes such as oxygen transfer into the sediment. So far, no highresolution flow velocity profiles close to the sediment-water interface have been reported for such systems because a suitable flow meter was lacking. This article introduces a novel sensor for the measurement of extremely lowflow velocities. The sensor is based on a gas transducer surrounded by a gas reservoir. It measures the change in the partial pressure of a tracer gas outside the reservoir tip due to advective transport. The sensor is suitable for measurements of velocities smaller than 1 mm s-1, with a spatial resolution of 100 to 250 μm. The flow measurements prove to be insensitive to temperature changes between 5 and 15 °C. The sensor is robust against relative pressure changes, and angular differences in the sensitivity can be calibrated. We present ...

2025, Industrial & Engineering Chemistry Research

We have recently showed the formation of transversal patterns in a 3D cylindrical reactor in which an exothermic first-order reaction of Arrhenius kinetics occurs with variable catalytic activity. Under these oscillatory kinetics, the system exhibits a planar front (1D) solution, with the front position oscillating in the axial direction, while in the 3D case, three types of transversal patterns can emerge: rotating fronts, oscillating fronts with superimposed transversal (nonrotating) oscillations, and mixed rotating-oscillating fronts. In the present study, we analyze the possible reduction of the 3D model to a 2D cylindrical shell model to predict patterns. We map bifurcation diagrams showing domains of different modes using the reactor radius (R) as a bifurcation parameter and show that the front divergence and the domains of the kn-mode pattern in the 3D model [corresponding to the transversal eigenfunction J k (µ kn r) exp(ikθ), in which J k is the Bessel function of the first kind] can be predicted by those of the one wave in the 2D model using the linear transformation R 3D ) µ kn R 2D .

2025, Journal of Engineering Research

Seismic Oceanography (SO) is an innovative method that uses seismic reflection data from surveys to study oceanographic features. We conducted a systematic review using the PRISMA method, retrieving 164 articles published between 2008 and 2023 from Web of Science and Scopus. Analyzing the data with Vosviewer and Bibliometrix software, we found that the SO methodology is expanding its applications and identified four sub-areas: 1) analyzing ocean background features, 2) mapping physical oceanographic features, 3) inverting and processing seismic data, and 4) studying interactions with the background. We traced the history of SO from its early studies in 1979 to recent works in 2023. Interestingly, the term "Seismic Oceanography" gained prominence after 2008, leading to the discovery of 15 additional articles through cross-referencing and citation analysis. Based on common processing techniques, we proposed a working guide with a flowchart for different types of seismic data, advanced processing, and relevant databases. This guide serves as a reference, offering professionals a historical perspective and practical guidance when applying the SO methodology. Our systematic review provides a comprehensive understanding of the current state of SO, identifies areas for further research, and introduces a valuable tool for professionals interested in utilizing the methodology.

2025, Journal of Geophysical Research

Evidence of a warm, salty surface current flowing poleward along the Iberian Peninsula is presented using a sequence of satellite infrared images and concomitant in situ hydrographic data obtained during the winter of 1983-1984. The current, which flows over 1500 km along the upper continental slope-shelf break zone off western Portugal, northwest and northern Spain, and southwest France, is 25-40 km wide, about 200 m deep, and characterized by velocities of 0.2--0.3 m s-•. According to the hydrographic data acquired during late November and early December 1983, the current's salinity signal off Portugal is about 0.2 practical salinity units, and its waters are -0.5øC warmer than the surrounding ones. The satellite observations, however, which span a longer time period and cover a much larger area, indicate that the current's typical thermal signature is 1ø-1.5øC. The current's associated geostrophic volume transports show an increase from about 300 x 103 m 3 s -• near 38ø3'N to 500-700 x 10 3 m 3 s -! at 41ø-42øN. The origin of this poleward flow and the causes for its increasing transport off western Iberia are investigated. Onshore Ekman convergence induced by southerly winds along the Portuguese west coast provides about one fifth of the computed transports in the correct direction. A mechanism giving better quantitative agreement with the observations is the geostrophic adjustment of the eastward oceanic flow driven by the large-scale meridional baroclinic pressure gradient in the eastern North Atlantic as the flow reaches the continental slope of the western Iberian Peninsula. Topographic trapping by the bathymetric step existing along the shelf break explains both the width and the path of the observed current. The role of "dam break" type mechanisms is discarded owing to strong discrepancies between the available models and the present observations. Since satellite images reveal that similar situations occurred during many winters, the flow identified here appears as a characteristic feature of the winter circulation off southwest Europe. Furthermore, the occurrence of analogous poleward flows in eastern boundary layers of the subtropical and mid-latitude oceans suggests that these currents are typical features of those regions' winter circulation. 1.

2025, Journal of Geophysical Research

The Heat Capacity Mapping Mission experimental satellite was launched in April 1978 and provided data until July 1980. Although the basic mission objective was the measurement of diurnal temperature variations of the earth's surface for soil and geology applications, the characteristics of the heat capacity mapping radiometer onboard the satellite (temperature sensitivity of 0.3øC, instantaneous field of view of 0.5 km) also recommended it for use in oceanographic studies. The data acquired during the period from May 1978 to May 1979 were systematically utilized for evaluation of sea surface temperature in French oceanic regions (North Sea, English Channel, Celtic Sea, Bay of Biscay, and western Mediterranean Sea) and for study of sea surface temperature-related dynamic phenomena. Comparisons were made of the radiometric performance of the heat capacity mapping radiometer to that of the very high resolution radiometer and the advanced very high resolution radiometer onboard meteorological satellites. They demonstrate the decisive gain in quality of the heat capacity mapping radiometer over the very high resolution radiometer and the similarly improved quality of the heat capacity mapping radiometer and advanced very high resolution radiometer for the observation of mesoscale sea surface temperature features. The utilization of available photographic products proved very suitable, since they had been. geometrically corrected and enhanced in the sea surface temperature range, consequently avoiding many of those cases requiring involved computer treatment. On the basis of the interpretation of photographic products, conclusions have been drawn regarding several oceanic phenomena:(1) The thermal effluent of the Rhine-Meuse system is affected by the residual tidal current of the North Sea. The extent of the offshore diffusion of the effluent is influenced by winds from the northeast and west whi•ch, respectively, retard or accelerate the residual current; (2) images exhibiting cold water along the edge of the continental shelf strongly support the hypothesis of a mixing process due to internal waves generated by the action of tidal currents at the edge of the shelf; (3) large-scale eddy structures detected during the summer in the region of the Mediterranean Sea around 6øE and 38øN may be linked to a phenomenon of barotropic-baroclinic instability; (4) significant diurnal heating of the surface layer (several degrees Celsius) observed in the Mediterranean Sea is related to the presence of weak winds, leading one to interpret with caution the daytime sea surface temperature satellite observations made during the summer period. 1. INTRODUCTION The utilization of spaceborne infrared scanners for observation of the earth's surface temperature field is now a common practice. The first experiments in this area were launched in the 1960's, but it was not until the early 1970's that the very high resolution radiometer (VHRR) on the polar-orbiting environmental satellites operated by the National Oceanic and Atmospheric Administration (NOAA) permitted a systematic and fairly precise observation of the earth's surface temperat•ure field. A large number of oceanic fronts have been detected and monitored in this manner from space (see, among other reviews, those by Lqgeckis [1978] and McClain [1980]). However, examination of even pronounced sea surface temperature (SST) features has still been somewhat limited by the instrumental performance of the VHRR (noise equivalent differential temperature (NEDT) of 0.5ø-1øC).

2025

We study the escape of rays from a two dimensional, specularly reflecting open cavity having the shape of a vase. At the narrowest point of the neck of the vase there is an unstable periodic orbit which defines a dividing surface between... more

2025, APS Meeting …

Experimental research on the interaction of two co-propagating solitary water waves was carried out, comparing it with the KdV Equation two-soliton solution. Experiments were conducted in a wave channel of width 0.8m, with a 30m length... more

2025, Phys. Fluids

The evolution of a Gaussian vortex subject to a weak-external-random nfold multipolar strain field is examined using fully nonlinear simulations. The simulations show that at large Reynolds numbers, fine scale steps form at the periphery of the vortex, before merging, generally leaving one large step, which acts as a barrier between the vorticity within the coherent core and the surrounding, well mixed, 'surf zone'. It is shown for n = 2 that the width and the number of fine scale steps which initially form at the periphery of the vortex is dependent on the strain parameters, but that the range of radial values for which steps initially occur is only dependent on n and the amplitude of the strain field. A criteria is developed which can predict this range of radial values using the linear stability results of Le Dizès (J. Fluid Mech., vol. 406, 2000, p.175). This criteria is based upon the perturbation vorticity needing to be larger than some fraction of the vorticity gradient to flatten the vortex profile. For n = 3 and 4, the radial step range is again predicted, and it is observed that for these higher wavenumbers the long lasting steps are narrower than the n = 2 case. For n = 4 the steps which form are so narrow that they do not persist very long before they are destroyed by the strain field and viscosity.

2025, J. Comput. Appl. Math.

A numerical method is proposed to solve the two-layer inviscid, incompressible and immiscible 1D shallow-water equations in a moving vessel with a rigid-lid with different boundary conditions based on the high-resolution f-wave finite volume methods due to Bale, LeVeque, Mitran and Rossmanith [7] (2002, SIAM J. Sci. Comput. 24). The method splits the jump in the fluxes and source terms including the pressure gradient at the rigid-lid into waves propagating away from each grid cell interface. For the influxefflux boundary conditions the time dependent source terms are handled via a fractional step approach. In the linear case the numerical solutions are validated by comparison with the exact analytical solutions. Numerical solutions presented for the nonlinear case include shallow-water sloshing waves due to prescribed surge motion of the vessel.

2025, Journal of Fluid Mechanics

This paper presents an experimental study on internal waves emitted by a horizontally oscillating torus in a linearly stratified fluid. Two internal wave cones are generated with the kinetic energy focused at the apices of the cones above and below the torus where the wave amplitude is maximal. Their motion is measured via tracking of distortions of horizontal fluorescein dye planes created prior to the experiments and illuminated by a vertical laser sheet. The distortion of the dye planes gives a direct access to the Lagrangian displacement of local wave amplitudes and slopes, and in particular, allows us to calculate a local Richardson number. In addition particle image velocimetry measurements are used. Maximum wave slopes are found in the focal region and close to the surface of the torus. As the amplitude of oscillations of the torus increases, wave profiles in the regions of maximum wave slopes evolve nonlinearly toward local overturning. A theoretical approximation based on the theory of Hurley & Keady (J. Fluid Mech., vol. 351, 1997, pp. 119-138) is presented and shows, for small amplitudes of oscillation, a very reasonable agreement with the experimental data. For the focal region the internal wave amplitude is found to be overestimated by the theory. The wave breaking in the focal region is investigated as a function of the Keulegan-Carpenter number, Ke = A/a, with A the oscillation amplitude and a the short radius of the torus. A linear wave regime is found for Ke < 0.4, nonlinear effects start at Ke ≈ 0.6 and breaking for Ke > 0.8. For large forcing, the measured wave amplitude normalized with the oscillation amplitude decreases almost everywhere in the wave field, but increases locally in the focal region due to nonlinear effects. Due to geometric focusing the amplitude of the wave increases with √ ǫ, with ǫ = b/a and b is the mean radius of the torus. The relevance of wave focusing due to ocean topography is discussed.

2025

The interaction of tidal motion with ocean bottom topography results in the radiation of internal gravity waves into the ocean interior, known as the baroclinic tide. Dissipation due to nonlinear breaking is believed to play an important role in the mixing of the abyssal ocean, and therefore in the large-scale ocean circulation. Over the past five decades the dynamics of particularly diverging internal waves have been considered, such as generated by an oscillating object, see for example Mowbray and Rarity (1967) for a cylinder, or King at al. (2009) and Ermanyuk et al (2011) for a sphere. Wave focusing is known to occur for wave reflection on inclined boundaries (Maas et al. 1997), but the geometric focusing as occurs for oscillating bodies of ring shaped topography is not well known, and only the case studied by Buhler and Muller (2007) who considered a ring with Gaussian generatrix placed at the bottom is known. Here we present results on internal waves in a linearly stratified ...

2025, Journal of Fluid Mechanics

2025

In this experimental-theoretical study we consider the waves emitted by a horizontally oscillating sphere in a linearly stratified fluid. In contrast to former investigations, the thus generated wave pattern is a-symmetric and three-dimensional. We consider large and small amplitude horizontal oscillations for different size spheres. The spatial structure of internal waves has a non-trivial dependence on the body geometry, direction

2025, Experiments in Fluids

The internal gravity waves and the turbulent wake of a sphere moving through stratified fluid were studied by the fluores cent dye technique. The Reynolds number Re= U • 2 a/v was kept nearly constant at about 3 • 103 and the Froude number F= U/aN ranged from 0.5 to 12.5. It is observed that waves generated by the body are dominant only when F < 4 and are replaced by waves generated by the large scale coherent structures of the wake when F>4.

2025, HAL (Le Centre pour la Communication Scientifique Directe)

HAL is a multi-disciplinary open access archive for the deposit and dissemination of scientific research documents, whether they are published or not. The documents may come from teaching and research institutions in France or abroad, or from public or private research centers. L'archive ouverte pluridisciplinaire HAL, est destinée au dépôt et à la diffusion de documents scientifiques de niveau recherche, publiés ou non, émanant des établissements d'enseignement et de recherche français ou étrangers, des laboratoires publics ou privés.

2025

Monomolecular surface films ("sea slicks") are well known to dampen small-scale waves at the water surface, and thereby to influence transport processes at the air-sea interface. Because of their strong wave-damping capabilities they can often be delineated on synthetic aperture radar (SAR) imagery, but also on satellite imagery acquired in the visible and infrared spectral ranges. Since sea slicks tend to accumulate at the water surface along shear current lines, fronts, eddies, etc., they can be used as a proxy for observing such marine processes from space. In order to document the dynamics of marine surface films under different environmental conditions we present the main results of our experimental efforts, as well as a selection of ERS and ENVISAT SAR images that demonstrate how well sea slicks are suited to indicate marine processes in the coastal zones.

2025, Estuaries

Nitrate and water quality parameters (temperature, salinity, dissolved oxygen, turbidity, and depth) were measured continuously with in situ NO 3 analyzers and water quality sondes at two sites in Elkhorn Slough in Central California. The Main Channel site near the mouth of Elkhorn Slough was sampled from February to September 2001. Azevedo Pond, a shallow tidal pond bordering agricultural fields further inland, was sampled from December 1999 to July 2001. Nitrate concentrations were recorded hourly while salinity, temperature, depth, oxygen, and turbidity were recorded every 30 min. Nitrate concentrations at the Main Channel site ranged from 5 to 65 M. The propagation of an internal wave carrying water from ϳ100 m depth up the Monterey Submarine Canyon and into the lower section of Elkhorn Slough on every rising tide was a major source of nitrate, accounting for 80-90% of the nitrogen load during the dry summer period. Nitrate concentrations in Azevedo Pond ranged from 0-20 M during the dry summer months. Nitrate in Azevedo Pond increased to over 450 M during a heavy winter precipitation event, and interannual variability driven by differences in precipitation was observed. At both sites, tidal cycling was the dominant forcing, often changing nitrate concentrations by 5-fold or more within a few hours. Water volume flux estimates were combined with observed nitrate concentrations to obtain nitrate fluxes. Nitrate flux calculations indicated a loss of 4 mmol NO 3 m Ϫ2 d Ϫ1 for the entire Elkhorn Slough and 1 mmol NO 3 m Ϫ2 d Ϫ1 at Azevedo Pond. These results suggested that the waters of Elkhorn Slough were not a major source of nitrate to Monterey Bay but actually a nitrate sink during the dry season. The limited winter data at the Main Channel site suggest that nitrate was exported from Elkhorn Slough during the wet season. Export of ammonium or dissolved organic nitrogen, which we did not monitor, may balance some or all of the NO 3 flux.

2025

1hls is an interim report of a goup in Topic-2 of the Core University Program. The fmal objective is to investigate the mechanism of beach erosion and propose counter measures including software and hardware. In this report, methodology to analyze the topography change that shoud be utilized in the analysis of topography change in some coasts in Vietnam are reviewed. Points at issue we have to solve and the data we need for applying methodology to the coast in Vietnam are discussed. KEYWORDS river mouth sand bar, river discharge, waves and wave-induced current, numerical model, beach erosion

2025, Journal of Physical Oceanography

Upstream mean semidiurnal internal tidal energy flux has been found in the Gulf Stream in hydrodynamical model simulations of the Atlantic Ocean. A major source of the energy in the simulations is the south edge of Georges Bank, where strong and resonant Gulf of Maine tidal currents are found. An explanation of the flux pattern within the Gulf Stream is that internal wave modal rays can be strongly redirected by baroclinic currents and even trapped (ducted) by current jets that feature strong velocities above the thermocline that are directed counter to the modal wavenumber vector (i.e., when the waves travel upstream). This ducting behavior is analyzed and explained here with ray-based wave propagation studies for internal wave modes with anisotropic wavenumbers, as occur in mesoscale background flow fields. Two primary analysis tools are introduced and then used to analyze the strong refraction and ducting: the generalized Jones equation governing modal properties and ray equations that are suitable for studying waves with anisotropic wavenumbers.

2025, The Journal of the Acoustical Society of America

The 1995 Shallow Water Acoustics in a Random Medium (SWARM) experiment was conducted off of the New Jersey coast [Apel et al., IEEE J. Ocean. Eng. (1997)]. The experiment featured two well-populated vertical receiving arrays allowing the measured acoustic field to be decomposed into its normal modes. The decomposition was repeated for successive transmissions allowing the amplitude of each mode to be tracked. The modal amplitudes were observed to decorrelate with time-scales of the order 100 s. In the present work, a theoretical model is proposed explaining the observed decorrelation. Internal solitary wave packets are modeled as mode coupling structures advecting along the acoustic propagation path. Motion of the packets cause the acoustic interference pattern to change. The model is first tested in simple continuous-wave simulations using canonical forms for the internal waves. More detailed time-domain simulations are presented mimicking the situation in SWARM. [Work supported by...

2025, Journal of Physical Oceanography

The spectral energy density of the internal waves in the open ocean is considered. The Garrett and Munk spectrum and the resonant kinetic equation are used as the main tools of the study. Evaluations of a resonant kinetic equation that suggest the slow time evolution of the Garrett and Munk spectrum is not in fact slow are reported. Instead, nonlinear transfers lead to evolution time scales that are smaller than one wave period at high vertical wavenumber. Such values of the transfer rates are inconsistent with the viewpoint expressed in papers by C. H. McComas and P. Mu ¨ller, and by P. Mu ¨ller et al., which regards the Garrett and Munk spectrum as an approximate stationary state of the resonant kinetic equation. It also puts the self-consistency of a resonant kinetic equation at a serious risk. The possible reasons for and resolutions of this paradox are explored. Inclusion of near-resonant interactions decreases the rate at which the spectrum evolves. Consequently, this inclusion shows a tendency of improving of self-consistency of the kinetic equation approach.

2025, arXiv (Cornell University)

We provide a first-principles analysis of the energy fluxes in the oceanic internal wavefield. The resulting formula is remarkably similar to the renowned phenomenological formula for the turbulent dissipation rate in the ocean which is known as the Finescale Parameterization. The prediction is based on the wave turbulence theory of internal gravity waves and on a new methodology devised for the computation of the associated energy fluxes. In the standard spectral representation of the wave energy density, in the two-dimensional vertical wavenumber -frequency (𝑚 -𝜔) domain, the energy fluxes associated with the steady state are found to be directed downscale in both coordinates, closely matching the Finescale-Parameterization formula in functional form and in magnitude. These energy transfers are composed of a 'local' and a 'scale-separated' contributions; while the former is quantified numerically, the latter is dominated by the Induced Diffusion process and is amenable to analytical treatment. Contrary to previous results indicating an inverse energy cascade from high frequency to low, at odds with observations, our analysis of all non-zero coefficients of the diffusion tensor predicts a direct energy cascade. Moreover, by the same analysis fundamental spectra that had been deemed 'no-flux' solutions are reinstated to the status of 'constant-downscale-flux' solutions. This is consequential for an understanding of energy fluxes, sources and sinks that fits in the observational paradigm of the Finescale Parameterization, solving at once two long-standing paradoxes that had earned the name of 'Oceanic Ultraviolet Catastrophe'.

2025, Physica D: Nonlinear Phenomena

To investigate the formation mechanism of energy spectra of internal waves in the oceans, direct numerical simulations are performed. The simulations are based on the reduced dynamical equations of rotating stratified turbulence. In the reduced dynamical equations only wave modes are retained, and vortices and horizontally uniform vertical shears are excluded. Despite the simplifications, our simulations reproduce some key features of oceanic internal-wave spectra: accumulation of energy at near-inertial waves and realistic frequency and horizontal wavenumber dependencies. Furthermore, we provide evidence that formation of the energy spectra in the inertial subrange is dominated by scale-separated interactions with the near-inertial waves. These findings support observationallybased intuition that spectral energy density of internal waves is the result of predominantly wavewave interactions.

2025, E-Gnosis ( …

The characteristics of internal waves in Bahía de Banderas were determined by means of oscillating CTD casts from a fast oceanographic survey done on April 24 and 25, 2001. Previous studies have shown that the continental shelf of the Mexican Pacific, including Bahía de Banderas, possesses favorable conditions for the generation on internal waves. Fluctuations of the hydrophysical characteristics of the continental shelf caused by the presence and propagation of internal waves are smoothed using a filter whose parameters are determined by the shape of the spatial correlation function of the field pulses relative to the analyzed characteristic. Once internal waves are filtered, temperature, salinity and geostrophic velocity fields are shown for different depths and the general pattern of the geostrophic circulation in the bay is discussed. The strongest currents were present south of Islas Marietas and at the east zone of the bay. It can be stated that the geostrophic circulation in the bay in spring has an important role in the water masses exchange between the zone close to the east coast, inside the bay, and the open ocean. Geostrophic currents, internal waves, temperature and salinity fields, Bahía de Banderas. Las características de las ondas internas en la Bahía de Banderas fueron determinadas por medio de lances con un CTD ondulante a partir de un muestreo oceanográfico rápido realizado los días 24 y 25 de abril de 2001. Estudios previos han mostrado que la plataforma continental del Pacífico mexicano, incluyendo la Bahía de Banderas, presenta condiciones favorables para la generación de ondas internas. Las fluctuaciones de las características hidrofísicas en el área de estudio fueron suavizadas mediante un filtro cuyos parámetros están determinados por la forma de la función de correlación espacial de los pulsos del campo de la característica analizada. Una vez filtrado el efecto de las ondas internas, se muestran los campos de temperatura, salinidad y velocidad geostrófica para diferentes profundidades y se discute el comportamiento de la circulación geostrófica en la bahía. Las corrientes más intensas se presentaron en la parte sur de las Islas Marietas y en la zona este de la bahía. Puede establecerse que la circulación geostrófica en primavera en el área de estudio tiene un papel importante en el intercambio de masas entre la zona próxima a la costa este, dentro de la bahía, y el océano abierto.

2025, Journal of the Acoustical Society of America

2025, Bulletin of the American Physical Society

The American Physical Society Anisotropic shear dispersion parameterization for ocean eddy transport SCOTT RECKINGER, Montana State University, BAYLOR FOX-KEMPER, Brown University -The effects of mesoscale eddies are universally treated isotropically in global ocean general circulation models. However, observations and simulations demonstrate that the mesoscale processes that the parameterization is intended to represent, such as shear dispersion, are typified by strong anisotropy. We extend the Gent-McWilliams/Redi mesoscale eddy parameterization to include anisotropy and test the effects of varying levels of anisotropy in 1-degree Community Earth System Model (CESM) simulations. Anisotropy has many effects on the simulated climate, including a reduction of temperature and salinity biases, a deepening of the southern ocean mixed-layer depth, impacts on the meridional overturning circulation and ocean energy and tracer uptake, and improved ventilation of biogeochemical tracers, particularly in oxygen minimum zones. A process-based parameterization to approximate the effects of unresolved shear dispersion is also used to set the strength and direction of anisotropy. The shear dispersion parameterization is similar to drifter observations in spatial distribution of diffusivity and high-resolution model diagnosis in the distribution of eddy flux orientation.

2025

2025, Physica D: Nonlinear Phenomena

A novel canonical Hamiltonian formalism is developed for long internal waves in a rotating environment. This includes the effects of background vorticity and shear on the waves. By restricting consideration to flows in hydrostatic balance, superimposed on a horizontally uniform background of vertical shear and vorticity, a particularly simple Hamiltonian structure arises, which can be thought of as describing a nonlinearly coupled infinite collection of shallow water systems. The kinetic equation describing the time evolution of the spectral energy of internal waves is subsequently derived, and a stationary Kolmogorov solution is found in the high frequency limit. This is surprisingly close to the Garrett-Munk spectrum of oceanic internal waves.

2025, arXiv (Cornell University)

2025, Nonlinear Processes in Geophysics

Observations of internal solitary waves over an antarctic ice shelf demonstrate that even large amplitude disturbances have wavelengths that are bounded by simple heuristic arguments following from the Scorer parameter based on linear theory for wave trapping. Classical weak nonlinear theories that have been applied to stable stratifications all begin with perturbations of simple long waves, with corrections for weak nonlinearity and dispersion resulting in nonlinear wave equations (Korteweg-deVries (KdV) or Benjamin-Davis-Ono) that admit localized propagating solutions. It is shown that these theories are apparently inappropriate when the Scorer parameter, which gives the lowest wavenumber that does not radiate vertically, is positive. In this paper, a new nonlinear evolution equation is derived for an arbitrary wave packet thus including one bounded below by the Scorer parameter. The new theory shows that solitary internal waves excited in high Richardson number waveguides are predicted to have a halfwidth inversely proportional to the Scorer parameter, in agreement with atmospheric observations. A localized analytic solution for the new wave equation is demonstrated, and its soliton-like properties are demonstrated by numerical simulation.

2025, Dynamics of Atmospheres and Oceans

Statistical characteristics are calculated for stationary velocity fluctuations in a one-dimensional open channel flow with a given vertical velocity profile and with one-dimensional irregular bottom waves, characterized by a spectral density function. The calculations are based on an approximate calculation of the velocity fluctuations in the fluid generated by a harmonic corrugation of the bottom. As linearized dynamical equations are used, the velocity fluctuations caused by random bottom disturbances may be obtained by superposition. The dynamics of the motion is assumed to be governed by the Orr-Sommerfeld equation representing the internal wave motion in the fluid. This equation is solved in an approximate manner by reducing it in the upper layer of the fluid to the Rayleigh equation. Close to the bottom we simplify it to a shape still containing the essentials of the viscous behaviour of the flow. Numerical examples and a tentative qualitative comparison with experimental data are given.

2025, J. Phys. Soc. Jpn.

We analyze the hydrodynamics of a rotating disk in a two-dimensional compressible fluid layer with odd viscosity. Unlike conventional fluids, odd viscosity introduces a radial flow component that can be directed either inward or outward, depending on its sign. This phenomenon is expected to significantly impact the hydrodynamic interactions between two rotating disks, potentially causing effective attraction or repulsion depending on the sign of the odd viscosity and the direction of rotation. Furthermore, we calculate the rotational resistance coefficient and find that odd viscosity increases this coefficient, regardless of its sign.

2025, Reviews of Geophysics

2025

The book Emperor of Holy Russia is devoted to the mental horizons, ideology, and collective perceptions of the Moscow tsardom of the fifteenth up to the early eighteenth centuries. The focus of the study includes such ideologemes as people and Holy Russia, tsar and emperor, post-apocalyptic history and the Third Rome, and such forms of collective political action as the people's cause, the common affaires (cf. res publica), and citizenship. Despite non-modern communication technologies, the intensive (sacred) reading, and unstable doctrines of sovereignty, Russian culture was in this period a legitimate part of the Renaissance world, as evidenced both by polemical writings, vocabulary and historical statements of intellectuals, monuments of ceremonial, historical, political, and everyday thought, and traces of the reception of world events, anonymous discourses, and visual representations of the present and the past. The Moscow kingdom was also involved in one of the most significant discussions of the modern era - about disarmament as a necessary condition for civil life.

2025, Nature

Small-scale turbulent mixing drives the upwelling of deep water masses in the abyssal ocean as part of the global overturning circulation 1 . However, the processes leading to mixing and the pathways through which this upwelling occurs remain insufficiently understood. Recent observational and theoretical work 2-5 has suggested that deep-water upwelling may occur along the ocean's sloping seafloor; however, evidence has, so far, been indirect. Here we show vigorous near-bottom upwelling across isopycnals at a rate of the order of 100 metres per day, coupled with adiabatic exchange of near-boundary and interior fluid. These observations were made using a dye released close to the seafloor within a sloping submarine canyon, and they provide direct evidence of strong, bottom-focused diapycnal upwelling in the deep ocean. This supports previous suggestions that mixing at topographic features, such as canyons, leads to globally significant upwelling 3,6-8 . The upwelling rates observed were approximately 10,000 times higher than the global average value required for approximately 30 × 10 6 m 3 s -1 of net upwelling globally 9 .

2025

First results of extensive ADCP and CTD measurements, performed in the Adriatic shelf-break area between February and September 2006, are presented. Pronounced diurnal oscillations were observed, apparently related to internal tides and periodic upwelling and downwelling events. Moreover, inertial oscillations were documented. Finally, summertime change of the east-coast inflow to the Adriatic was recorded, lasting only one month at two ADCP stations, three months at one station.

2025, Ukraina Moderna

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2025, Journal of Geophysical Research

Semidiurnal internal tides drive strong flow variations on the shelf between Timor Island and Australia. The variability of the internal tide over seasonal to interannual time scales is studied using temperature and velocity measurements from 11 moorings, a first attempt for an observational regional synthesis of internal tide behavior. The energy density and flux carried by the semidiurnal tides were calculated from the full water column profile estimated by the Gauss-Markov fit of the vertical modes incorporating the effects of sloping bottom topography. The estimated energy flux can be interpreted either as generated at and propagating from nearby forcing sites where strong barotropic tides flow over steep topography or as trapped by and circulating around an island topography. The relevant horizontal length scale of the topography is several tens of kilometers, which is the wavelength of the vertical first-mode internal tides. At some of the moorings with sufficiently long records, seasonal variations of energy density and flux are found with maxima in late summer to winter, which is the same phase as the seasonal variation of the temperature stratification between 100 and 200 m depths. The relationship between the temperature stratification and the internal tide energy density is not linear. For the energy density, the amplitude of the seasonal variation as well as the standard deviation correlates well with the mean value with a correlation coefficient >0.8 and a p value <0.03, but the correlation between the energy density and area-integrated barotropic tidal forcing is not significant.