scholarly journals WAVE - INDUCED DEVICES FOR THE OXYGENATION OF DEEP LAYER: A PHYSICAL INVESTIGATION

2012 ◽  
Vol 1 (33) ◽  
pp. 56 ◽  
Author(s):  
Alessandro Antonini ◽  
Maria Gabriella Gaeta ◽  
Alberto Lamberti
Keyword(s):  
Atlantic Coast ◽  
Water Flux ◽  
Vertical Mixing ◽  
Wave Climate ◽  
Environmental Variable ◽  
Mixing Processes ◽  
Coastal Marine ◽  
Short Period ◽  
Ecological Importance ◽  
Wave Induced

No other environmental variable of ecological importance to estuarine and coastal marine ecosystems around the world has changed so drastically, in such a short period of time, as dissolved oxygen. Coastal surveys in United States and Europe found that a staggering 78 % of the assessed continental U.S. coastal area and approximately 65 % of Europe’s Atlantic coast exhibit symptoms of eutrophication. The 65 % of the coasts counted by Diaz does not take into account inland seas like the Adriatic or Baltic Seas but also for these, eutrophication and consequently anoxia are common problems. In the present study a simple and economic device is proposed to enhance vertical mixing processes and to induce aeration of deep water by pumping of oxygen-rich surface water downwards to a desired depth around the halocline. The hydrodynamic parameters of the device are estimated through free oscillation tests. Preliminary values of the downward water flux velocity inside the device and the movements of the floater under the action of 4 regular waves, characterizing of the wave climate in the Nord Adriatic Sea, are estimated.

scholarly journals MATHEMATICAL MODELLING OF WAVE-INDUCED NEARSHORE CIRCULATIONS

1986 ◽  
Vol 1 (20) ◽  
pp. 122 ◽  
Author(s):  
Donghoon Yoo ◽  
Brian A. O'Connor
Keyword(s):  
Experimental Data ◽  
Present Model ◽  
Wave Climate ◽  
Mixing Processes ◽  
Diffraction Wave ◽  
Waves And Currents ◽  
Current Interaction ◽  
Induced Currents ◽  
Set Up ◽  
Wave Induced

The paper presents a mathematical model for describing wave climate and wave-induced nearshore circulations. The model accounts for current-depth refraction, diffraction, wave-induced currents, set-up and set-down, mixing processes and bottom friction effects on both waves and currents. The present model was tested against published experimental data on wave conditions within a model harbour and shown to give very good results for both wave and current fields. The importance of including processes such as advection, flooding and current-interaction in coastal models was demonstrated by comparing the numerical results without each process to the results from the complete scheme.

scholarly journals A Hydrodynamical Model for Calculating the Vertical Temperature Profile in Lakes During Cooling

1983 ◽  
Vol 14 (4) ◽  
pp. 239-254 ◽  
Author(s):  
Jörgen Sahlberg
Keyword(s):  
Heat Flux ◽  
Temperature Profile ◽  
Vertical Mixing ◽  
Hydrodynamical Model ◽  
Measured Temperature ◽  
Vertical Temperature ◽  
Mixing Rate ◽  
Mixing Processes ◽  
Vertical Temperature Profile ◽  
Radiation Fluxes

A one-dimensional hydrodynamical model is used for simulating the vertical temperature profile in a lake during cooling conditions. The vertical mixing rate is calculated by solving the equations for turbulent kinetic energy, k, and dissipation of energy, ε. The heat exchange between the water and atmosphere consists of the radiation fluxes, sensible and latent heat flux. Temperature measurements from Lake Väsman during November-December, 1981, were used in the verification study. The agreement between calculated and measured temperature profiles is very good. This indicates that both the mixing processes and the net heat flux are well described in the model.

Marine Reservoir Corrections on the Southeastern Coast of Brazil: Paired Samples from the Saquarema Shellmound

Radiocarbon ◽  
2015 ◽  
Vol 57 (4) ◽  
pp. 517-525 ◽  
Author(s):  
Eduardo Alves ◽  
Kita Macario ◽  
Rosa Souza ◽  
Orangel Aguilera ◽  
Ana Carolina Goulart ◽  
...  
Keyword(s):  
Atlantic Coast ◽  
Archaeological Site ◽  
Brazilian Coast ◽  
The Holocene ◽  
Southeastern Coast ◽  
Archaeological Material ◽  
Paired Samples ◽  
Coastal Marine ◽  
Janeiro State ◽  
Fish Otoliths

The Saquarema archaeological site, on the Atlantic coast of the Rio de Janeiro State, is one of many shellmounds built on the Brazilian coast by hunter-gatherer populations during the Holocene. We used archaeological material from this site with the aim of evaluating the marine reservoir effect (MRE) in the region. Radiocarbon ages of 45 marine and 6 terrestrial samples from this shellmound provided data for assessing the MRE and the influences of freshwater and seasonal coastal marine upwelling in this specific locality. Samples of charcoal, fish otoliths, and mollusk shells were analyzed and the 14C dates were modeled in the OxCal platform to determine the marine reservoir correction. The result obtained is R = 265 ± 70 14C yr and the offset ΔR was found to be –140 ± 66 14C yr. To support the accuracy of this value for correcting conventional 14C marine ages, taxonomic analyses of the samples were performed.

Wave induced turbulence effect on oceanic biogeochemistry and study of ocean color response to changing wave climate

2021 ◽  
Author(s):  
Chinglen Meetei Tensubam ◽  
Alexander V. Babanin
Keyword(s):  
Net Primary Productivity ◽  
Mixed Layer Depth ◽  
Marine Ecosystem ◽  
Ocean Color ◽  
Ocean Waves ◽  
Wave Climate ◽  
Upper Ocean ◽  
P Value ◽  
Chl A ◽  
Wave Induced

<p>The role of surface ocean waves becomes substantial in the upper ocean layer mixing. Due to turbulence induced by the surface waves (both broken and unbroken waves), the upper ocean mixing is enhanced, and important upper ocean parameters are affected such as lowering of sea surface temperature (SST), deepening of mixed layer depth (MLD) and most interestingly, the changes in oceanic biogeochemistry. The main objective of this study is to analyze the effect of wave induced turbulence on oceanic biogeochemistry such as the supply and distribution of nutrients to tiny plants in the ocean called phytoplanktons, and how it affects their concentrations. Marine phytoplanktons formed the basis of marine ecosystem which accounts for about 45 percent of global net primary productivity and play an important part in global carbon cycle. The population of phytoplanktons depends mainly on nutrients (both micro and macro), availability of sunlight and grazing organisms. For this study, we use global coupled ocean-sea ice model ACCESS-OM2 with biogeochemical module called WOMBAT to estimate the effect of wave induced turbulence and study the difference between ‘with waves’ and ‘without waves’ effect on oceanic biogeochemistry. The same effect of wave induced turbulence on oceanic biogeochemistry are also studied by incorporating the change in wave climate such as increase in significant wave height and wind speed. From the investigation of merged satellite ocean color data from ESA’s GlobColour project for the period of 23 years between 1997 and 2019, it was found that chlorophyll-a (Chl-a, an index of phytoplankton biomass) concentration showed increasing trend of 0.015 mg/m3 globally and 0.062 mg/m3 in the Southern Ocean (SO) for the study period with p-value less than 0.01. It was also found that most of the increasing trends are shown spatially in the open ocean and decreasing trend in the coastal regions during the study period.</p>

Numerical Experiments Analysis of Wave-Induced Vertical Mixing’s Effects on Sea Surface Wind-Induced Momentum Transfer

2010 ◽  
Author(s):  
Bingchen Liang ◽  
Ying Liu ◽  
Lili Yang
Keyword(s):  
Fresh Water ◽  
Yellow River ◽  
Vertical Section ◽  
Vertical Mixing ◽  
Three Dimensional ◽  
Velocity Profiles ◽  
Dimensional Model ◽  
One Dimensional ◽  
Wave Induced ◽  
Sediment Model

A hydrodynamic sediment coupled model COHERENS-SED, which has been developed by the present authors through introducing wave-enhanced bottom stress, wave dependent surface drag coefficient, wave-induced surface mixing, SWAN, damping function of sediment on turbulence and sediment model to COHERENS, is modified to account for wave-induced vertical mixing. One equation k–ε turbulence model is taken into account in calculating vertical viscosity coefficient. COHERENS-SED consists of sediment model SED, current model COHERENS and wave generation model SWAN. The model can also calculate one-dimensional, two-dimensional and three-dimensional current separately. One-dimensional model and three-dimensional model are adoptted to study the wave-induced vertical mixing’s effects. The horizontal current velocity profiles given by the model, with same input conditions as what to get analytical results, are in nice agreement with analytical velocity profiles. Therefore the model can be reliable to identify wave-induced vertical mixing’s effects on horizontal velocity profiles and momentum transferring. Two group numerical experiments are built based on 130m water depth and 20m water depth for the one-dimensional model. Results show that higher wave height can generate larger vertical eddy viscosity and lower horizontal velocity generally. In order to find out such effects on fresh water flume momentum transfer towards down in vertical section of estuary, Yellow River delta is chosen to study the effects of wave-induced vertical diffusion on sediment vertical mixing and the Yellow River estuary vertical cross-section is chosen to study fresh water disperse range in vertical section. The results of fresh water shows that wave-induced vertical mixing increases the momentum of fresh water transferring ability towards down to seabed. So fresh water flume length is compressed obviously.

scholarly journals Near-Inertial Mixing in the Central Arctic Ocean

2014 ◽  
Vol 44 (8) ◽  
pp. 2031-2049 ◽  
Author(s):  
Ilker Fer
Keyword(s):  
Arctic Ocean ◽  
Vertical Mixing ◽  
The Arctic ◽  
Storm Event ◽  
Central Arctic Ocean ◽  
Long Time ◽  
Wave Induced ◽  
The Waves ◽  
Inertial Energy ◽  
Made In

Abstract Observations were made in April 2007 of horizontal currents, hydrography, and shear microstructure in the upper 500 m from a drifting ice camp in the central Arctic Ocean. An approximately 4-day-long time series, collected about 10 days after a storm event, shows enhanced near-inertial oscillations in the first half of the measurement period with comparable upward- and downward-propagating energy. Rough estimates of wind work and near-inertial flux imply that the waves were likely generated by the previous storm. The near-inertial frequency band is associated with dominant clockwise rotation in time of the horizontal currents and enhanced dissipation rates of turbulent kinetic energy. The vertical profile of dissipation rate shows elevated values in the pycnocline between the relatively turbulent underice boundary layer and the deeper quiescent water column. Dissipation averaged in the pycnocline is near-inertially modulated, and its magnitude decays approximately at a rate implied by the reduction of energy over time. Observations suggest that near-inertial energy and internal wave–induced mixing play a significant role in vertical mixing in the Arctic Ocean.

Key factors in vertical mixing processes in a reservoir bordering the Pantanal floodplain, Brazil

2015 ◽  
Vol 60 (9) ◽  
pp. 1508-1519 ◽  
Author(s):  
Ibraim Fantin-Cruz ◽  
Olavo Pedrollo ◽  
Cláudia C. Bonecker ◽  
Peter Zeilhofer
Keyword(s):  
Vertical Mixing ◽  
Key Factors ◽  
Mixing Processes

scholarly journals Silent oceans: ocean acidification impoverishes natural soundscapes by altering sound production of the world's noisiest marine invertebrate

2016 ◽  
Vol 283 (1826) ◽  
pp. 20153046 ◽  
Author(s):  
Tullio Rossi ◽  
Sean D. Connell ◽  
Ivan Nagelkerken
Keyword(s):  
Ocean Acidification ◽  
Sound Production ◽  
Marine Invertebrate ◽  
Empirical Test ◽  
Sound Level ◽  
Similar Reduction ◽  
Snapping Shrimp ◽  
Larval Stages ◽  
Coastal Marine ◽  
Ecological Importance

Soundscapes are multidimensional spaces that carry meaningful information for many species about the location and quality of nearby and distant resources. Because soundscapes are the sum of the acoustic signals produced by individual organisms and their interactions, they can be used as a proxy for the condition of whole ecosystems and their occupants. Ocean acidification resulting from anthropogenic CO 2 emissions is known to have profound effects on marine life. However, despite the increasingly recognized ecological importance of soundscapes, there is no empirical test of whether ocean acidification can affect biological sound production. Using field recordings obtained from three geographically separated natural CO 2 vents, we show that forecasted end-of-century ocean acidification conditions can profoundly reduce the biological sound level and frequency of snapping shrimp snaps. Snapping shrimp were among the noisiest marine organisms and the suppression of their sound production at vents was responsible for the vast majority of the soundscape alteration observed. To assess mechanisms that could account for these observations, we tested whether long-term exposure (two to three months) to elevated CO 2 induced a similar reduction in the snapping behaviour (loudness and frequency) of snapping shrimp. The results indicated that the soniferous behaviour of these animals was substantially reduced in both frequency (snaps per minute) and sound level of snaps produced. As coastal marine soundscapes are dominated by biological sounds produced by snapping shrimp, the observed suppression of this component of soundscapes could have important and possibly pervasive ecological consequences for organisms that use soundscapes as a source of information. This trend towards silence could be of particular importance for those species whose larval stages use sound for orientation towards settlement habitats.

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