scholarly journals Surface Imprints of Water-Column Turbulence: A Case Study of Tidal Flow over an Estuarine Sill

2013 ◽  
Vol 5 (7) ◽  
pp. 3239-3258 ◽  
Author(s):  
George Marmorino ◽  
Geoffrey Smith ◽  
W. Miller
Keyword(s):  
Water Column ◽  
Tidal Flow

scholarly journals Turbulence and hypoxia contribute to dense biological scattering layers in a Patagonian fjord system

Ocean Science ◽  
2018 ◽  
Vol 14 (5) ◽  
pp. 1185-1206 ◽  
Author(s):  
Iván Pérez-Santos ◽  
Leonardo Castro ◽  
Lauren Ross ◽  
Edwin Niklitschek ◽  
Nicolás Mayorga ◽  
...  
Keyword(s):  
Kinetic Energy ◽  
Water Column ◽  
Turbulent Kinetic Energy ◽  
Tidal Flow ◽  
Vertical Mixing ◽  
Acoustic Doppler Current Profiler ◽  
Marine Species ◽  
Eddy Diffusivity ◽  
Diel Vertical Migrations

Abstract. The aggregation of plankton species along fjords can be linked to physical properties and processes such as stratification, turbulence and oxygen concentration. The goal of this study is to determine how water column properties and turbulent mixing affect the horizontal and vertical distributions of macrozooplankton along the only northern Patagonian fjord known to date, where hypoxic conditions occur in the water column. Acoustic Doppler current profiler moorings, scientific echo-sounder transects and in situ plankton abundance measurements were used to study macrozooplankton assemblages and migration patterns along Puyuhuapi Fjord and Jacaf Channel in Chilean Patagonia. The dissipation of turbulent kinetic energy was quantified through vertical microstructure profiles collected throughout time in areas with high macrozooplankton concentrations. The acoustic records and in situ macrozooplankton data revealed diel vertical migrations (DVM) of siphonophores, chaetognaths and euphausiids. In particular, a dense biological backscattering layer was observed along Puyuhuapi Fjord between the surface and the top of the hypoxic boundary layer (∼100 m), which limited the vertical distribution of most macrozooplankton and their DVM, generating a significant reduction of habitat. Aggregations of macrozooplankton and fishes were most abundant around a submarine sill in Jacaf Channel. In this location macrozooplankton were distributed throughout the water column (0 to ∼200 m), with no evidence of a hypoxic boundary due to the intense mixing near the sill. In particular, turbulence measurements taken near the sill indicated high dissipation rates of turbulent kinetic energy (ε∼10-5 W kg−1) and vertical diapycnal eddy diffusivity (Kρ∼10-3 m2 s−1). The elevated vertical mixing ensures that the water column is well oxygenated (3–6 mL L−1, 60 %–80 % saturation), creating a suitable environment for macrozooplankton and fish aggregations. Turbulence induced by tidal flow over the sill apparently enhances the interchange of nutrients and oxygen concentrations with the surface layer, creating a productive environment for many marine species, where the prey–predator relationship might be favored.

scholarly journals A BEM for the Hydrodynamic Analysis of Oscillating Water Column Systems in Variable Bathymetry

Energies ◽  
2020 ◽  
Vol 13 (13) ◽  
pp. 3403 ◽  
Author(s):  
Kostas Belibassakis ◽  
Alexandros Magkouris ◽  
Eugen Rusu
Keyword(s):  
Boundary Element Method ◽  
Water Column ◽  
Black Sea ◽  
Bottom Topography ◽  
The Black Sea ◽  
Device Performance ◽  
Oscillating Water Column ◽  
Energy Potential ◽  
Hydrodynamic Analysis

In this work, a novel Boundary Element Method (BEM) is developed and applied to the investigation of the performance of Oscillating Water Column (OWC) systems, taking into account the interaction of the incident wave field with the bottom topography. The modelling includes the effect of additional upwave walls and barriers used to modify the resonance characteristics of the device and improve its performance as the U-OWC configuration. Numerical results illustrating the effects of depth variation in conjunction with other parameters—such as chamber dimensions as well as the parameters associated with the turbine and power take-off system—on the device performance are presented and discussed. Finally, a case study is presented regarding the potential installation of an OWC in a selected port site in the Black Sea, characterized by a good wave energy potential, on the coast of Romania.

scholarly journals A Simple Parameterization of Turbulent Tidal Mixing near Supercritical Topography

2010 ◽  
Vol 40 (9) ◽  
pp. 2059-2074 ◽  
Author(s):  
Jody M. Klymak ◽  
Sonya Legg ◽  
Robert Pinkel
Keyword(s):  
Internal Wave ◽  
Water Column ◽  
Numerical Models ◽  
Tidal Flow ◽  
Internal Tides ◽  
Tidal Mixing ◽  
Knife Edge ◽  
Wave Interactions ◽  
Tidal Dissipation ◽  
Midocean Ridges

Abstract A simple parameterization for tidal dissipation near supercritical topography, designed to be applied at deep midocean ridges, is presented. In this parameterization, radiation of internal tides is quantified using a linear knife-edge model. Vertical internal wave modes that have nonrotating phase speeds slower than the tidal advection speed are assumed to dissipate locally, primarily because of hydraulic effects near the ridge crest. Evidence for high modes being dissipated is given in idealized numerical models of tidal flow over a Gaussian ridge. These idealized models also give guidance for where in the water column the predicted dissipation should be placed. The dissipation recipe holds if the Coriolis frequency f is varied, as long as hN/W ≫ f, where N is the stratification, h is the topographic height, and W is a width scale. This parameterization is not applicable to shallower topography, which has significantly more dissipation because near-critical processes dominate the observed turbulence. The parameterization compares well against simulations of tidal dissipation at the Kauai ridge but predicts less dissipation than estimated from observations of the full Hawaiian ridge, perhaps because of unparameterized wave–wave interactions.

scholarly journals Environmental Conditions in a Carpathian Deep Sea Basin During the Period Preceding Oceanic Anoxic Event 2 - A Case Study from the Skole Nappe

2015 ◽  
Vol 65 (5) ◽  
pp. 433-450 ◽  
Author(s):  
Krzysztof Bąk ◽  
Marta Bąk ◽  
Zbigniew Górny ◽  
Anna Wolska
Keyword(s):  
Water Column ◽  
Deep Sea ◽  
Silica Content ◽  
Turbidity Currents ◽  
Ecological Groups ◽  
Deep Basin ◽  
Oceanic Anoxic Event ◽  
Plankton Production ◽  
Basin Floor

Abstract Hemipelagic green clayey shales and thin muddy turbidites accumulated in a deep sea environment below the CCD in the Skole Basin, a part of the Outer Carpathian realm, during the Middle Cenomanian. The hemipelagites contain numerous radiolarians, associated with deep-water agglutinated foraminifera. These sediments accumulated under mesotrophic conditions with limited oxygen concentration. Short-term periodic anoxia also occurred during that time. Muddy turbidity currents caused deposition of siliciclastic and biogenic material, including calcareous foramini-fers and numerous sponge spicules. The preservation and diversity of the spicules suggests that they originate from disarticulation of moderately diversified sponge assemblages, which lived predominantly in the neritic-bathyal zone. Analyses of radiolarian ecological groups and pellets reflect the water column properties during the sedimentation of green shales. At that time, surface and also intermediate waters were oxygenated enough and sufficiently rich in nutri-ents to enable plankton production. Numerous, uncompacted pellets with nearly pristine radiolarian skeletons inside show that pelletization was the main factor of radiolarian flux into the deep basin floor. Partly dissolved skeletons indicate that waters in the Skole Basin were undersaturated in relation to silica content. Oxygen content might have been depleted in the deeper part of the water column causing periodic anoxic conditions which prevent rapid bacterial degra-dation of the pellets during their fall to the sea floor.

Microbial transformation of jellyfish organic matter affects the nitrogen cycle in the marine water column — A Black Sea case study

2016 ◽  
Vol 475 ◽  
pp. 19-30 ◽  
Author(s):  
Tinkara Tinta ◽  
Tjaša Kogovšek ◽  
Valentina Turk ◽  
Tamara A. Shiganova ◽  
Alexander S. Mikaelyan ◽  
...  
Keyword(s):  
Organic Matter ◽  
Water Column ◽  
Black Sea ◽  
Nitrogen Cycle ◽  
Microbial Transformation ◽  
Marine Water

Insights for lake management gained when paleolimnological and water column monitoring studies are combined: A case study from Baptiste Lake

2013 ◽  
Vol 30 (1) ◽  
pp. 11-22 ◽  
Author(s):  
Katrina E. Adams ◽  
Zofia E. Taranu ◽  
Ron Zurawell ◽  
Brian F. Cumming ◽  
Irene Gregory-Eaves
Keyword(s):  
Water Column ◽  
Lake Management
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