Dissipation Of Internal Tides Research Articles

Semidiurnal Internal Tides in a Shelf Sea South of Japan: Characteristics, Energetics, and Temporal variations

Tidal mixing in a shelf sea south of Japan (Bungo Channel) plays an important role in modulating the water exchange between the Seto Inland Sea and Pacific Ocean. In this study, based on moored observations and model results from the Japan Coastal Ocean Predictability Experiment—Tides (JCOPE-T), the generation, propagation, and dissipation of semidiurnal internal tides in the Bungo Channel are investigated. Observational results indicate that semidiurnal internal tides induce strong baroclinic currents reaching 0.3 m/s. Their energy shows obvious spring-neap tidal cycles, generally coinciding with the local barotropic tidal forcing. By conducting the empirical orthogonal function analysis, we find that the observed semidiurnal internal tides are mainly dominated by the first two baroclinic modes. The JCOPE-T results suggest two main generation sites for semidiurnal internal tides in the region: one is located at a narrow strait north of the Bungo Channel, while the other is at the shelf break south of the Bungo Channel. The latter makes a major contribution to the observed semidiurnal internal tides. Northward internal tides generated at the shelf break are superposed with those generated at the narrow strait, causing a complex interference pattern in the channel. The temporal variation of semidiurnal internal tides in the Bungo Channel is affected by several factors. The intraseasonal variation of semidiurnal internal tides can be modulated by the Kuroshio warm water intrusion (Kyucho) because the occurrence of Kyucho changes the stratification in the channel and hence affects the energy conversion. The seasonal variation of semidiurnal internal tides in the Bungo Channel is determined mainly by the seasonally varying stratification; while those generated at the shelf break are under the combined influence of seasonal stratification and background currents. Southward internal tides from the shelf break are refracted due to the spatially varying stratification and background currents. The varying Kuroshio path and strength modulate the refraction of internal tides.

Enhanced Dissipation of Internal Tides in a Mesoscale Baroclinic Eddy

Abstract The dissipation of low-mode internal tides as they propagate through mesoscale baroclinic eddies is examined using a series of numerical simulations, complemented by three-dimensional ray tracing calculations. The incident mode-1 internal tide is refracted into convergent energy beams, resulting in a zone of reduced energy flux in the lee of the eddy. The dissipation of internal tides is significantly enhanced in the upper water column within strongly baroclinic (anticyclonic) eddies, exhibiting a spatially asymmetric pattern, due to trapped high-mode internal tides. Where the eddy velocity opposes the internal tide propagation velocity, high-mode waves can be trapped within the eddy, whereas high modes can freely propagate away from regions where eddy and internal wave velocities are in the same direction. The trapped high modes with large vertical shear are then dissipated, with the asymmetric distribution of trapping leading to the asymmetric distribution of dissipation. Three-dimensional ray tracing solutions further illustrate the importance of the baroclinic current for wave trapping. Similar enhancement of dissipation is also found for a baroclinic cyclonic eddy. However, a barotropic eddy is incapable of facilitating robust high modes and thus cannot generate significant dissipation of internal tides, despite its strong velocities. Both energy transfer from low to high modes in the baroclinic eddy structure and trapping of those high modes by the eddy velocity field are therefore necessary to produce internal wave dissipation, a conclusion confirmed by examining the sensitivity of the internal tide dissipation to eddy radius, vorticity, and vertical scale. Significance Statement The oceanic tides drive underwater waves at the tidal frequency known as internal tides. When these waves break, or dissipate, they can lead to mixing of oceanic heat and salt which impacts the ocean circulation and climate. Accurate climate predictions require computer models that correctly represent the distribution of this mixing. Here we explore how an oceanic eddy, a swirling vortex of order 100–400 km across, can locally enhance the dissipation of oceanic internal tides. We find that strong ocean eddies can be hotspots for internal tide dissipation, for both clockwise and anticlockwise rotating vortices, and surface-enhanced eddies are most effective at internal tide dissipation. These results can improve climate model representations of tidally driven mixing, leading to more credible future predictions.

Radiation and energetics of M2 internal tides in the Okhotsk Sea

Tidal mixing around the Kuril Island Chain (KIC) significantly modulates the transport of Okhotsk Sea Mode Water into the Pacific Ocean and, hence, the formation of North Pacific Intermediate Water. Although previous studies have revealed the dominant role of trapped K1 internal tides in driving mixing, the energetic M2 internal tides that have been observed by altimetry are not sufficiently clarified. In this study, we investigated the generation, radiation, and dissipation of semidiurnal M2 internal tides in the Okhotsk Sea using a high-resolution model. The results showed that KIC is the main generation site for M2 internal tides, with an integrated energy conversion of 2.07 GW. The generated M2 internal tides propagated over a long distance into the Okhotsk Sea and Northern Pacific Ocean and exhibited asymmetry on the two sides of the KIC. In addition, the generation of M2 internal tides on the Kashevarov Bank in the northwestern Okhotsk Sea made a minor contribution. Although the integrated dissipation of the M2 internal tides at KIC was lower than that of the K1 internal tides, the M2 internal tidal energy dissipation rates exceeded 10−8 W/kg near the topography. More importantly, energy dissipation in the far field was dominated by radiating M2 internal tides, which induced higher diapycnal diffusivity than K1 internal tides. These results revealed the important role of M2 internal tides in driving mixing at KIC and surrounding regions, which was previously overlooked.

Along-slope bottom currents driven by dissipation of internal tides in the northeastern South China Sea

Recent mooring observations on the continental slope on the east side of the Dongsha Island in the northeastern South China Sea (SCS) showed that an along-slope bottom current can be generated when internal tides obliquely incident to the slope are dissipated near the seafloor. In this study, new mooring data collected on the south side of the Dongsha Island are used to explore the universality of internal wave driven the bottom currents and test the ability of the previous theory in estimating the along-slope current. The data show strong near-bottom energy dissipation due to the critical reflection of diurnal internal tides on the continental slope, with a time-mean depth-integrated dissipation rate of ~4.8×10-3 W/m2. Because of the obliquely incident of diurnal internal tides to the slope, near-bottom dissipation of internal tides generates a southwestward along-slope current, with the maximum velocity exceeding 6 cm/s. By comparing the observations, the previous theory for internal wave induced mean flows developed by Thorpe (1999) shows a good ability to estimate the along-slope bottom current velocity. Based on the theory, as well as modelled energy dissipation on the entire continental slope in the northeastern SCS, a map is obtained to quantitatively describe the along-slope bottom flow caused by internal tide breaking on the slope.

Energy balance and momentum budgets due to the internal tides generated by a group of submarine canyons

A field multibeam survey discovered a group of regularly-spaced submarine canyons on the continental shelf in the northern South China Sea. However, they are not included in the bathymetry datasets commonly used by the oceanographic community. In this study, we employ a very-high-resolution (as fine as 54 m) numerical model that resolves these submarine canyons to investigate their impacts on the local internal tide generation and propagation. Results show that the barotropic to internal tidal conversion rate exhibits an alternating distribution on each flank of submarine canyons. Rotational direction of the tidal flow determines a positive conversion rate on the west flank and a negative rate on the east flank. The rough seafloor due to the submarine canyons does not appreciably change the dissipation of barotropic tides, but significantly affects the dissipation of internal tides, leading to an averaged dissipation rate of 1.2 × 10−9 W kg −1. Internal tides also induce a bottom intensified mean flow, which causes westward mean transport on the continental slope and a clockwise circulation inside each submarine canyon. The mean flow satisfies a momentum budget between the Coriolis force, pressure gradient and divergence of momentum flux of barotropic and internal tides. We highlight that the divergence of the pseudo-momentum flux of internal tides acts as a stress and is especially reinforced near the sea bottom and surface. Its effect on the sea surface is even comparable with moderate winds (∼13 m s−1).

Development History of the Numerical Simulation of Tides in the East Asian Marginal Seas: An Overview

As a ubiquitous movement in the ocean, tides are vital for marine life and numerous marine activities such as fishing and ocean engineering. Tidal dynamics are complicated in the East Asian marginal seas (EAMS) due to changing complex topography and coastlines related to human activities (e.g., land reclamation and channel deepening) and natural variability (e.g., seasonal variations of ocean stratification and river flow). As an important tool, numerical models are widely used because they can provide basin-scale patterns of tidal dynamics compared to point-based tide gauges. This paper aims to overview the development history of the numerical simulation of tides in the EAMS, including the Bohai Sea, the Yellow Sea, the East China Sea, the East/Japan Sea, and the South China Sea, provide comprehensive understanding of tidal dynamics, and address contemporary research challenges. The basic features of major tidal constituents obtained by tidal models are reviewed, and the progress in the inversion of spatially and temporally changing model parameters via the adjoint method are presented. We review numerical research on how a changing ocean environment induces tidal evolution and how tides and tidal mixing influence ocean environment in turn. The generation, propagation, and dissipation of internal tides in the EAMS are also reviewed. Although remarkable progresses in tidal dynamics have been made, nonstationary tidal variations are not fully explained yet, and further efforts are needed. In addition, tidal influences on ocean environment still receive limited attention, which deserves special attention.

Updated parameterization of internal tidal mixing in the deep ocean based on laboratory rotating tank experiments

The Coriolis effect plays an important role in the generation and dissipation of internal tides. In this study, the effects of the Coriolis parameter on internal tides generated by tidal current flowing over rough subsurface topography were investigated in the laboratory. The results show that the variation in the internal tidal local dissipation rate with variation in the Coriolis parameter in the deep layer follows a Gaussian distribution. The strongest dissipation occurs near the critical latitude where the local Coriolis parameter is half of the tidal frequency. A modified internal tidal mixing parameterization was developed by introducing a correction function related to the Coriolis effect on internal tidal local dissipation in the deep ocean, based on the original version developed by St. Laurent et al. (2002). The new parameterization was then implemented in a parallel ocean model. The results indicate that the deep global meridional overturning circulation (GMOC) is strengthened in the low and middle latitudes and the Southern Ocean by the change, compared with the original parameterization.

Dissipation and Bathymetric Sensitivities in an Unstructured Mesh Global Tidal Model

AbstractThe mechanisms and geographic distribution of global tidal dissipation in barotropic tidal models are examined using a high resolution unstructured mesh finite element model. Mesh resolution varies between 2 and 25 km and is especially focused on inner shelves and steep bathymetric gradients. Tidal response sensitivities to bathymetric changes are examined to put into context response sensitivities to frictional processes. We confirm that the Ronne Ice Shelf dramatically affects Atlantic tides but also find that bathymetry in the Hudson Bay system is a critical control. We follow a sequential frictional parameter optimization process and use TPXO9 data‐assimilated tidal elevations as a reference solution. From simulated velocities and depths, dissipation within the global model is estimated and allows us to pinpoint dissipation at high resolution. Boundary layer dissipation is extremely focused with 1.4% of the ocean accounting for 90% of the total. Internal tide friction is much more distributed with 16.7% of the ocean accounting for 90% of the total. Often highly regional dissipation can impact basin‐scale and even ocean wide tides. Optimized boundary layer friction parameters correlate very well with the physical characteristics of the locality with high friction factors associated with energetic tidal regions, deep ocean island chains, and ice covered areas. Global complex M2 tide errors are 1.94 cm in deep waters. Total global boundary layer and internal tide dissipation are estimated, respectively, at 1.83 and 1.49 TW. This continues the trend in the literature toward attributing more dissipation to internal tides.

Investigation of Internal Tides Variability in the Andaman Sea: Observations and Simulations

AbstractThe Andaman Sea in the Indian Ocean is known for the presence of large‐amplitude Internal waves (IW). Internal tides (IT) are IW of tidal frequency whose temporal variability is unknown in this region. Therefore, we used in‐situ observations collected at (10.5°N, 94°E) from March 2017 to February 2018. The analysis shows that the kinetic energy of semidiurnal IT is dominant to that of diurnal IT by a factor of 4–5. The ellipticity of both semidiurnal and diurnal motions is dominated by rectilinear zonal flow, indicating generation at the slopes of the Andaman and Nicobar islands. Maximum isopycnal displacement reached 46 m for semidiurnal IT. The semidiurnal IT displayed significant seasonal variability—Stronger in summer and autumn but weaker in spring and winter, whereas the diurnal IT are relatively stronger in summer and winter. Furthermore, salinity plays a dominant role in controlling the near‐surface stratification, whereas the temperature variations control the subsurface stratification. This led to the formation of a strong double pycnocline during autumn and winter. Baroclinic coherent semidiurnal (diurnal) variance accounts for 49% (27%) of the semidiurnal (diurnal) motions. Model simulations carried out for March, June, September, and December of 2017 using the Massachusetts Institute of Technology General Circulation Model showed significant seasonal variability in the generation and dissipation of IT. The isopycnal displacement near the generation sites is about 88 m. The experiments suggest that the presence of the Andaman Nicobar Ridge contributes nearly 89% to the total IT generation.

Model Simulation of M2 Internal Tide at the Mariana Double Ridges

In this study, M2 tidal energy and tide-induced mixing in the Mariana double ridges are investigated with a high-resolution three-dimensional non-hydrostatic numerical model and baroclinic energy budget analysis. The interference effect of the double ridges on the internal tide in the Mariana is examined by omitting either the eastern or the western ridge. Our results show that the baroclinic velocity on the sides of the interior facing slopes of the double ridges is larger than that on the other sides. In the double ridges, high values of dissipation reaching O (10−6 W kg−1) are accompanied by diapycnal diffusivity reaching O (10−1 m2 s−1), which is several orders of magnitude higher than the mixing of the open ocean. The bottom diapycnal mixing in the inner region between the two ridges is one order of magnitude larger than the mixing outside the ridges, indicating the important role of the interference of the double-ridge topography on the mixing in the Mariana Arc. Omitting either the eastern or the western ridge would have a significant impact on tide current, baroclinic energy flux and dissipation, and diapycnal mixing. The internal tide conversion, dissipation, and flux divergence are amplified by the double ridge topography, especially in the central part of the double ridges. Through energy budgets analysis, we conclude that the eastern ridge is the main source of the baroclinic tide in the Mariana double ridges.

Diversity in Vertical Structures of Internal Tide Dissipation Rate Around the Indonesian Throughflow Exits Simulated by a High‐Resolution Nonhydrostatic Model

AbstractThe vertical structure of internal tide dissipation rate ϵ is essential to the parameterization of the internal tide‐induced mixing, yet its diversity has always been oversimplified in ocean circulation models. Based on a high‐vertical‐resolution (10 m) simulation around the exits of the Indonesian throughflow, the diversity in ϵ profiles near both the bottom and the thermocline was investigated by a hierarchical clustering classification. Five typical near‐bottom vertical structures of ϵ were found, of which the bottom‐intensified structure is dominant. From the maximum dissipation depths to the shallower water, all five profiles obey the same decaying function. There are three typical near‐thermocline structures of ϵ: one menifests the thermocline‐intensified pattern and the other two feature a surface‐intensified pattern characterized by a monotonic increase from 500‐m depth to the surface. All three vertical structures near thermocline could be scaled by the reciprocal of the Richardson number.

The Three‐Dimensional Internal Tide Radiation and Dissipation in the Mariana Arc‐Trench System

AbstractInternal tides are energetic in the Mariana arc, but their three‐dimensional radiation and dissipation remain unexplored, particularly the trench‐arc‐basin impacts. Here, the generation, propagation and dissipation of M2 internal tides over the Mariana area are examined using a series of observation‐supported high‐resolution simulations. The M2 barotropic to baroclinic conversion rate amounts to 8.35 GW, of which two arc‐shaped ridges contribute ∼81% of the generated energy. The contributions to generation by the Mariana basin and deep trench are weak. Nevertheless, they are important in modulating the energy radiation and dissipation, since tidal beams can spread to these areas. The Mariana ridges radiate the westward‐focused and eastward‐spreading tidal beams. This is very consistent with the altimetric measurements. The resonance in the ridge center enhances the westward converging beam, which can travel across the Palau Ridge, 800 km away. In contrast, the eastward beams propagate over a limited lateral range, but can radiate and dissipate significant energy in the deep water column, reaching even to the abyssal Mariana trench. The direct estimation from the model results reveals the dissipation's multilayer vertical profile in the entire water column, and is well consistent with the finescale parameterization estimate based on vertical strain. However, the estimate of an oft‐used energy balance method, which typically assumes an exponentially decaying vertical structure function for the dissipation rate based on distance above the seafloor, is largely inconsistent with the measurements. Our findings highlight the complexity of three‐dimensional radiation paths and dissipation map of internal tides in the Mariana area.

Energetics‐Based Estimation of the Diapycnal Mixing Induced by Internal Tides in the Andaman Sea

AbstractThe Andaman Sea (AS) is characterized by surprisingly weak stratification in its deep basin in drastic contrast to the nearby Bay of Bengal (BoB), presumably due to strong diapycnal mixing fertilized by the dissipation of internal tides. Here, we report on the first estimates of tidal mixing in the AS using idealized numerical simulations resolving the generation and evolution of low‐mode internal tides. The estimation is based on a diagnostic analysis of the energetics of the simulated internal tides of both local and non‐local origins. The results highlight the dominant role of the internal tides generated in the channels along the western boundary island chain in energizing diapycnal mixing in the entire AS. Tidal dissipation and mixing in the deep basin of the AS are found to be highly elevated, with the depth‐integrated dissipation rate and the diapycnal diffusivity being O(10−2–10 ) W m−2 and O(10−3–10−2) m2 s−1, respectively, both of which are 1–2 orders of magnitude larger than those in the deep BoB. These model‐based estimates of tidal mixing are in general consistent with those from in situ conductivity‐temperature‐depth (CTD) measurements using the fine‐scale parameterization. Our results suggest that the oft‐used tidal mixing parameterization considering only local internal tide generation would underestimate the depth‐integrated tidal dissipation in the AS by several orders of magnitude, highlighting therefore the necessity of considering contributions of non‐local internal tides in parameterizing tidal dissipation and mixing in marginal seas like the AS.

Three‐Dimensional Numerical Simulations of Internal Tides in the Angolan Upwelling Region

AbstractIn austral winter, biological productivity at the Angolan shelf reaches its maximum. The alongshore winds, however, reach their seasonal minimum suggesting that processes other than local wind‐driven upwelling contribute to near‐coastal cooling and upward nutrient supply, one possibility being mixing induced by internal tides (ITs). Here, we apply a three‐dimensional ocean model to simulate the generation, propagation, and dissipation of ITs at the Angolan continental slope and shelf. Model results are validated against moored acoustic Doppler current profiler and other observations. Simulated ITs are mainly generated in regions with a critical/supercritical slope typically between the 200‐ and 500‐m isobaths. Mixing induced by ITs is found to be strongest close to the coast and gradually decreases offshore thereby contributing to the establishment of cross‐shore temperature gradients. The available seasonal coverage of hydrographic data is used to design simulations to investigate the influence of seasonally varying stratification characterized by low stratification in austral winter and high stratification in austral summer. The results show that IT characteristics, such as their wavelengths, sea surface convergence patterns, and baroclinic structure, have substantial seasonal variations and additionally strong spatial inhomogeneities. However, seasonal variations in the spatially averaged generation, onshore flux, and dissipation of IT energy are weak. By evaluating the change of potential energy, it is shown, nevertheless, that mixing due to ITs is more effective during austral winter. We argue that this is because the weaker background stratification in austral winter than in austral summer acts as a preconditioning for IT mixing.

Generation, propagation and dissipation of internal tides on the continental shelf and slope off the west coast of India

The present study focuses on the dynamics of M2 internal tides on the shelf and slope off the west coast of India (WCI) using a high-resolution (1/48∘) numerical ocean circulation model configured for the eastern Arabian Sea. The WCI is characterized by the presence of large internal tides where most of the internal tides generated on shelf-slope regions propagate offshore as beams. Baroclinic energy budget estimates show that about 2.4 GW of barotropic tides gets converted to baroclinic tides over the region. The regions of shelf breaks and upper slope around 16–18.5∘ N and the northern part of the Chagos-Laccadive Ridge (8–14∘ N) are the two most important regions of internal tide generation along the WCI, which together contribute to more than 50% of total area-integrated M2 conversion over the domain. The diapycnal diffusivity for internal tide dissipation exceeds 10−3m2/s in these regions. The central and northern slope regions off the WCI are dominated by locally generated internal tides, whereas part of internal tides in the southern region is characterized by the presence of remotely-generated internal tides coming from the Chagos-Laccadive Islands. Internal tides experience significant seasonal variation on the shelf owing to the variation in stratification, while their variations are negligible on the slope, where the seasonal variation in stratification is not significant.

Internal Tide Cycle and Topographic Scattering Over the North Mid‐Atlantic Ridge

AbstractInternal tides are a predominant source of high‐frequency variability and diapycnal mixing in the ocean. Understanding their dynamics and lifecycle is necessary to better understand their role in the ocean circulation. In this study, we describe and quantify internal tide generation, propagation, and dissipation in a sector of the North Mid‐Atlantic Ridge, using high‐resolution numerical simulations with realistic bathymetry and stratification. We show that the generation and dissipation of internal tides, as well as the distribution of internal tides among vertical modes, exhibit high spatial variability. We find that topographic scattering leads to a significant transfer of energy toward high vertical modes and thereby enhances internal tide dissipation. On average, and especially on the ridge, this mechanism is dominant over the conversion from the barotropic tide for transferring energy to high (7) vertical modes. The magnitude of the scattering of the first baroclinic internal mode is found to be in good agreement with theoretical predictions.

A Parameterization of Local and Remote Tidal Mixing

AbstractVertical mixing is often regarded as the Achilles' heel of ocean models. In particular, few models include a comprehensive and energy‐constrained parameterization of mixing by internal ocean tides. Here, we present an energy‐conserving mixing scheme which accounts for the local breaking of high‐mode internal tides and the distant dissipation of low‐mode internal tides. The scheme relies on four static two‐dimensional maps of internal tide dissipation, constructed using mode‐by‐mode Lagrangian tracking of energy beams from sources to sinks. Each map is associated with a distinct dissipative process and a corresponding vertical structure. Applied to an observational climatology of stratification, the scheme produces a global three‐dimensional map of dissipation which compares well with available microstructure observations and with upper‐ocean finestructure mixing estimates. This relative agreement, both in magnitude and spatial structure across ocean basins, suggests that internal tides underpin most of observed dissipation in the ocean interior at the global scale. The proposed parameterization is therefore expected to improve understanding, mapping, and modeling of ocean mixing.

Internal Tide Generation and Dissipation by Small Periodic Topography in Deep Ocean

Internal tides generated by a rough sea floor are an important source of mixing in the abyssal ocean. Two linear models are employed to evaluate the conversion rate from barotropic tides to internal tides and the energy distribution in each mode. Considering the periodicity of internal tides, the topography is represented by periodically distributed knife edges and sinusoidal ridges within one wavelength of mode-1 internal tides. The knife edges generate greater internal tides than the sinusoidal ridges due to their sharp shape, which approximates an extremely supercritical condition. Energy flux concentrates in modes whose numbers are multiples of the knife edge or ridge number. Then, a fully nonlinear model that integrates viscosity and diffusion is implemented, and its results are compared with those of the linear model. Internal wave rays generated in the nonlinear model show a distribution similar to the linear models’ prediction. High dissipation rates coincide with the rays, suggesting that nonlinear wave-wave interaction is a dominant mechanism for internal tide dissipation in the abyssal ocean.

Deep-ocean mixing driven by small-scale internal tides

Turbulent mixing in the ocean is key to regulate the transport of heat, freshwater and biogeochemical tracers, with strong implications for Earth’s climate. In the deep ocean, tides supply much of the mechanical energy required to sustain mixing via the generation of internal waves, known as internal tides, whose fate—the relative importance of their local versus remote breaking into turbulence—remains uncertain. Here, we combine a semi-analytical model of internal tide generation with satellite and in situ measurements to show that from an energetic viewpoint, small-scale internal tides, hitherto overlooked, account for the bulk (>50%) of global internal tide generation, breaking and mixing. Furthermore, we unveil the pronounced geographical variations of their energy proportion, ignored by current parameterisations of mixing in climate-scale models. Based on these results, we propose a physically consistent, observationally supported approach to accurately represent the dissipation of small-scale internal tides and their induced mixing in climate-scale models.

Toward global maps of internal tide energy sinks

Internal tides power much of the observed small-scale turbulence in the ocean interior. To represent mixing induced by this turbulence in ocean climate models, the cascade of internal tide energy to dissipation scales must be understood and mapped. Here, we present a framework for estimating the geography of internal tide energy sinks. The mapping relies on the following ingredients: (i) a global observational climatology of stratification; (ii) maps of the generation of M2, S2 and K1 internal tides decomposed into vertical normal modes; (iii) simplified representations of the dissipation of low-mode internal tides due to wave-wave interactions, scattering by small-scale topography, interaction with critical slopes and shoaling; (iv) Lagrangian tracking of low-mode energy beams through observed stratification, including refraction and reflection. We thus obtain a global map of the column-integrated energy dissipation for each of the four considered dissipative processes, each of the three tidal constituents and each of the first five modes. Modes ≥6 are inferred to dissipate within the local water column at the employed half-degree horizontal resolution. Combining all processes, modes and constituents, we construct a map of the total internal tide energy dissipation, which compares well with observational inferences of internal wave energy dissipation. This result suggests that tides largely shape observed spatial contrasts of dissipation, and that the framework has potential in improving understanding and modelling of ocean mixing. However, sensitivity to poorly constrained parameters and simplifying assumptions entering the parameterized energy sinks calls for additional investigation. The attenuation of low-mode internal tides by wave-wave interactions needs particular attention.