Dynamics of Internal Tides Over a Shallow Ridge Investigated With a High‐Resolution Downscaling Regional Ocean Model

Masunaga, Eiji; Uchiyama, Yusuke; Suzue, Yota; Yamazaki, Hidekatsu

doi:10.1002/2017gl076916

Cited by 23 publications

(27 citation statements)

References 23 publications

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“…It would also be interesting to examine how ocean mixing in a more realistic 3D environment would affect zooplankton dispersion. Although 3D simulations can provide further details of physical processes, the primary internal wave dynamics are similar for both 2D and 3D simulations (see Masunaga et al 2018Masunaga et al , 2019.…”

Section: Limitationsmentioning

confidence: 99%

Diel vertical migration promotes zooplankton horizontal patchiness

et al. 2020

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Spatial patchiness of plankton enhances fishery production and carbon export in the ocean. While diel vertical migration (DVM) has been identified as an important factor contributing to vertical patchiness, its effect on horizontal patchiness has never been investigated. We use a simple individual-based zooplankton model to examine the effect of DVM on the horizontal patchiness of four zooplankton groups with differing DVM patterns in a two-dimensional ocean circulation model. We find that zooplankton horizontal patchiness can be induced by two mechanisms: (1) in stratified waters, DVM can synchronize zooplankton vertical positions with the horizontal current velocities that drive them, resulting in horizontal patchiness; and (2) migrating zooplankton tend to aggregate in deep waters when they encounter sea bottom. Due to these mechanisms, zooplankton horizontal patchiness may be ubiquitous in the ocean, enhancing secondary production and fisheries.

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Section: Limitationsmentioning

confidence: 99%

Diel vertical migration promotes zooplankton horizontal patchiness

et al. 2020

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“…In addition, recent studies have suggested that tidal forcing noticeably influences the current and eddy field by modification of the kinetic energy flux via internal waves [e.g. Masunaga et al 2018;32]. To investigate the effect of downscaling and tidal variability on oceanic flow, eddies, and the resultant radionuclide distribution, we conducted statistical analyses by using the results obtained using the four models over the period between January 22 and 1 February 2016.…”

Section: Effects Of Downscaling and Tidementioning

confidence: 99%

Development of regional downscaling capability in STEAMER ocean prediction system based on multi-nested ROMS model

Kamidaira

Kawamura

Kobayashi

et al. 2019

Journal of Nuclear Science and Technology

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Oceanic regional downscaling capability was implemented into Short-Term Emergency Assessment system of Marine Environmental Radioactivity (STEAMER) developed by Japan Atomic Energy Agency to enable us to predict more realistically the oceanic dispersion of radionuclides at higher spatiotemporal resolutions for broader applications. The system consisted of a double-nested oceanic downscaling circulation model with tidal forcing and an oceanic radionuclide dispersion model. This system was used to comparatively examine downscaling and tidal effects on the dispersion of radionuclides hypothetically released from the Fukushima Daiichi Nuclear Power Plant in the colder season. The simulated dissolved 137 Cs distribution was different from that obtained using coarser-resolution models because downscaling enhanced both horizontal and vertical mixing. The suppression of horizontal mixing and the promotion of vertical mixing by tidal forcing synergistically reduced offshore 137 Cs transport. In addition, the submesoscale effects strengthened the three-dimensional 137 Cs fluctuations by <10 times, while the tidal effects promoted slightly increased the intensity of three-dimensional 137 Cs fluctuations by approximately 3%. This indicated that the submesoscale effects substantially surpassed tidal forcing in oceanic mixing in the coastal margin off Fukushima in the colder season.

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“…Tidal forcing is a major contributor to internal waves, and internal waves with tidal frequencies are called internal tides. The interaction of the tidal flow and shallow ridges/sills is one of the major factors contributing to internal tide generation (Alford et al 2015;Da Silva et al 2015;Masunaga et al 2018). The energy of internal waves increases when the topographic slope angle matches the beam angle of internal waves known as the critical slope (Cacchione et al 2002).…”

Section: Introductionmentioning

confidence: 99%

“…Internal waves transport energy from generation sites and finally break, inducing turbulence and mixing. Shoreward propagating internal waves increase their nonlinearity and generate strong turbulent mixing on shallow slopes (Richards et al 2013;Masunaga et al 2015), occasionally causing sediment resuspension and mass transport (Masunaga et al 2017a).…”

Section: Introductionmentioning

confidence: 99%

“…The interaction between barotropic tidal currents and the ridge generates internal waves (Masunaga et al 2017b(Masunaga et al , 2018. Masunaga et al (2018) conducted numerical simulations considering all possible processes (three-dimensional flows, tides, winds, and heat, radiation, and freshwater water fluxes). They found that 92% of the total internal wave flux was caused by internal tides, which contributed to 10% of the total kinetic energy in the study area.…”

Section: Introductionmentioning

confidence: 99%

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

Masunaga

Uchiyama

Yamazaki

2019

Journal of Physical Oceanography

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The 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 (Fr i = 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 Fr i 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 (Fr i ~ 1), which may lead to deep ocean mixing and transport at significant distances from the internal wave generation sites.

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Dynamics of Internal Tides Over a Shallow Ridge Investigated With a High‐Resolution Downscaling Regional Ocean Model

Cited by 23 publications

References 23 publications

Diel vertical migration promotes zooplankton horizontal patchiness

Diel vertical migration promotes zooplankton horizontal patchiness

Development of regional downscaling capability in STEAMER ocean prediction system based on multi-nested ROMS model

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

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