Sea Depth Research Articles

KM3NeT underwater autonomous power supply system

The KM3NeT Collaboration aims to build in the depths of the Mediterranean Sea a neutrino telescope that consists of a kilometer-cube grid of photosensors encapsulated into transparent pressure resistant glass spheres. A crucial component of the detector is the acoustic positioning system, which provides the position of photodetectors and structures in the deep sea with an accuracy of about 10 cm. The system is based on measurements of acoustic signals between fixed seabed emitters and receiving hydrophones. A subset of the required acoustic beacons is powered by an autonomous power supply system based on a high-charge battery pack. This paper describes the innovative design used to build the battery packs, derived from the expertise in the construction of underwater detectors encapsulated in glass vessels. The battery pack uses a pressure resistant 17-inch glass sphere as housing, which contains a cluster of 96 batteries properly connected to supply an output DC voltage of 12 V with a total capacity of 410 Ah. The cluster of batteries is surrounded by silicone glue, that stacks all the part together, ensuring mechanical connection with the housing and protecting the batteries against humidity. In order to increase the operating time of the beacon, a custom designed wake-up board is added to implement a duty cycle operating mode. An electronic switch controlled by an ARDUINO microprocessor connects the battery pack to the beacon only for a defined time. So far, 8 supply systems have been deployed at the KM3NeT sites. The beacon battery pack could be easily modified for multipurpose deep-sea applications.

Dispersal patterns of Squamata in the Mediterranean: An evolutionary perspective.

Mediterranean islands have a high diversity of squamates, although they are unevenly distributed. This variability in the composition of the reptile assemblages across islands may have been influenced by differences in the colonization abilities of these species. To evaluate the dispersal capacities of squamate species, we modeled their sea routes using cost surface models. We estimated the effects of some life‐history traits and the phylogenetic signal in the characteristics of the modeled dispersal paths. We hypothesized that a significant phylogenetic signal should be present if the dispersal ability is enhanced by traits shared among evolutionarily related species. The results showed that no phylogenetic signal was present in the characteristics of the dispersal paths (i.e., in the distance traveled/bypassed sea depth). Thus, no superior island‐colonizer lineages were detected in Mediterranean Squamata. However, our analyses also revealed that small‐sized lizards were superior to other groups of squamates at dispersing over long distances on the sea.

Variation in the distribution of yellowfin sole Limanda aspera larvae in warm and cold years in the eastern Bering Sea

AbstractMultiyear periods of relatively cold temperatures (2007–2013) and warm temperatures (2001–2005 and 2014–2018) altered the eastern Bering Sea ecosystem, affecting ocean currents and wind patterns, plankton community, and spatial distribution of fishes. Yellowfin sole Limanda aspera larvae were collected from the inner domain (≤50 m depth) of the eastern Bering Sea among four warm years (2002, 2004, 2005, 2016), an average year (2006), and three cold years (2007, 2010, 2012). Spatial distribution and density of larvae among those years was analyzed using generalized additive models that included timing of sea‐ice retreat, areal coverage of water ≤0°C, and water temperature as covariates. Analyses indicated a combination of temperature effects on the location and timing of spawning, and on egg and larval survival, may explain the variation in larval density and distribution among years. During warm years, higher density and wider spatial distribution of larvae may be due to earlier spawning, an expansion of the spawning area, and higher egg and larvae survival due to favorable temperatures. Larval distribution contracted shoreward, and density was lower during cold conditions and was likely due to fish spawning closer to shore to remain in preferred temperatures, later spawning, and increased mortality. Predicted drift trajectories from spawning areas showed that larvae would reach nursery grounds in most years. Years when the drift period was longer than the pelagic phase of the larvae occurred during both warm and cold conditions indicating that settlement outside of nursery areas could happen during either temperature condition.

Reconstruction of Ocean Front Model Based on Sound Speed Clustering and Its Effectiveness in Ocean Acoustic Forecasting

As a mesoscale phenomenon of the ocean, the ocean front can directly affect the structural characteristics of sound speed profiles and further affect the acoustic propagation characteristics of the sea area. In this paper, we use the fuzzy C-means (FCM) algorithm to cluster the surface sound speed in the sea area of the Kuroshio Extension (KE) and detect the frontal zone of Kuroshio Extension (KEF). At the same time, the sound speed profile (SSP) is used instead of the temperature profile to establish the model of the sound speed field in the front area of the Kuroshio Extension and to improve the theoretical model of the ocean front. Compared with the actual ocean front calculated by reanalysis data, the root means square error (RSME) of the transmission loss (TL) calculated by the model is controlled below 6 dB, which proves the validity of the model. Finally, we propose the melt function in the model to forecast the depth change of the acoustic convergence area. Compared with the actual calculation result based on reanalysis data, the root means square error (RSME) of the depth forecasting after the frontal zone is 43.3 m. This reconstruction method does not rely on the high spatial resolution data of the whole sea depth and can be of referential significance to acoustic detection in the ocean front environment.

Arc extinction with nitrogen at 1-40 bar in a puffer-like contact configuration

To develop cost-efficient subsea switchgear for large sea depths, the extinction of arcs under high filling pressures must be understood. In this work, arc-extinction experiments have been performed with a puffer-like contact configuration using nitrogen at different filling pressures as the current interruption medium. The main finding is that, for the given contact configuration, the currentinterruption capability was lower at 20 and 40 barabs than at 1 and 10 barabs. While higher pressures result in higher cooling flow rates and longer flow times given the same puffer volume, compression spring and nozzle geometry; it does not necessarily improve the arc-extinction capability. This is probably because higher filling pressures increase the arc voltage and total energy dissipated in the arcing zone. Because the filling pressure greatly influences the flow characteristics, the puffer design should be optimized for each pressure level.

Conceptual monopile and tower sizing for the IEA Wind Task 37 Borssele reference wind farm

This paper explores the preliminary design of the support structures for the IEA Wind Task 37 reference wind farm at the Borssele site III and IV. The study looks at two different design methods that might be used within larger wind farm system design optimization (i.e. lay-out, electrical systems, etc.). The first consists of a scaling tool that scales a detailed design according to the rated power, water depth, hub height and rotor diameter. The second is a physics-based optimization approach that relies on the WISDEM® design tool. This research compares the results of these two methods for the design of both the tower and monopile of the IEA 10-MW and 15-MW reference wind turbines at a range of sea depths (25 m, 30 m, 35 m, 40 m). The two tools yield very similar results in terms of monopile base diameter, support structure natural frequency and mass. WISDEM is then used to also investigate the sensitivity of the design to the tower top forces, wave conditions and the soil conditions. It is shown that tower top forces dominate the design. In general, large diameter structures can carry additional costs associated with manufacturing and transportation requirements. Thus, the paper is concluded with a trade-off study between mass and diameter that quantifies the effect of the reduction in monopile diameter with the increase in structural mass.

Characteristics of Low-Frequency Acoustic Wave Propagation in Ice-Covered Shallow Water Environment

Mastering the sound propagation law of low-frequency signals in the Arctic is a major frontier basic research demand to improve the level of detection, communication, and navigation technology. It is of practical significance for long-distance sound propagation and underwater target detection in the Arctic Ocean. Therefore, how to establish an effective model to study the characteristics of the acoustic field in the Arctic area has always been a hot topic in polar acoustic research. Aimed at solving this problem, a mathematical polar acoustic field model with an elastic seafloor is developed based on a range-dependent elastic parabolic equation theory. Moreover, this method is applied to study the characteristics of polar sound propagation for the first attempt. The validity and effectiveness of the method and model are verified by the elastic normal mode method. Simultaneously, the propagation characteristics of low-frequency signals are studied in a polar sound field from three aspects, which are seafloor parameters, sea depth, and ice thickness. The results show that the elastic parabolic equation method can be well utilized to the Arctic low-frequency acoustic field. The analysis of the influence factors of the polar sound field reveals the laws of sound transmission loss of low-frequency signals, which is of great significance to provide information prediction for underwater submarine target detection and target recognition.

Morphometry and unusual internal structure of ice ridge investigated at Barneo ice camp in April 2013

First-year ice ridge has been examined with respect to geometry and morphology at the Barneo ice camp in April 2013. Its characteristics are discussed in the paper. The sail height was 4.7 m, the keel depth was 8.6 m. The keel depth to sail height ratio was equal to 1.8. Structure of the keel of the examined ice ridge was too heterogeneous in its composition. Significant fragment in the keel of ice ridge is fully consolidated, its draft reaches to 5.8 m but the fragment's upper boundary is located at the sea level. This indicates the presence of hydrostatic unbalance. Away from the point of maximum keel draft on the cross-section, the average porosity of the unconsolidated part of the keel tends to increase, but again decreases at the periphery of the keel. The distribution of ice fraction in sea ice versus depth for the ice ridge is presented. Increased ice fraction corresponds to the consolidated layer. The depth of the lower boundary of consolidated layer is confirmed by distributions of ice temperature versus depth.

Hydrogen farm concept: A Perspective for Turkey

Hydrogen farm concept: A Perspective for Turkey

Insight to corrosion mechanism of 90/10 copper-nickel alloys under different sea depths

In this paper, for the first time, the corrosion behavior of 90/10 copper-nickel alloys was investigated systematically by simulating the different sea depths using static weight loss test, XPS depth analysis (argon ion etching), and electrochemical method. The static weight loss test showed that the average corrosion rate increased first, and then decreased with the increase of sea depth. XPS spectra demonstrated that the composition of the corrosion product layer did not change with variation of sea depth. The outer corrosion product was mainly CuO, Cu2O, Cu2Cl, NiO, and γ-FeOOH, while the inner corrosion product was mainly Cu2(OH)3Cl, Cu2O, NiO, Ni(OH)2, and γ-FeOOH. Electrochemical impedance spectroscopy exhibited that the inner corrosion layer played an important role in protecting the alloy.

Density and Diversity of Zooplankton in Palu Bay after the Tsunami Disaster 28 September 2018

One of the marine areas in Central Sulawesi is Palu Bay. Research on the Density and Diversity of Zooplankton Species in the Palu Bay area of Central Sulawesi after the Tsunami Disaster 28 September 2018. This study aims to determine: Density and Diversity Index of Zooplankton Species. Sampling is carried out at the beginning of the month by considering the state of the neighbours, namely the transition between the first and second full tides when the tidal currents are weak. The research design used a completely randomized design model with seasons, stations, and depths as treatments. Community analysis based on species identification, number of individuals, density, diversity index,. The results showed that the composition of the zooplankton community in the Palu bay area after the Tsunami Disaster of 28 September 2018 consisted of 23 types of zooplankton, which were dominated by: the Copepoda group. The values of the Density and Diversity Index are influenced by habitat, time, and sea depth. The conclusion is that habitat or station, season, and depth are the 3 main factors that affect the density and diversity of zooplankton taxon species in the Palu Bay area.

Techno-Economic Assessment of Offshore Wind Energy in the Philippines

The technical and economic assessments for emerging renewable energy technologies, specifically offshore wind energy, is critical for their improvement and deployment. These assessments serve as one of the main bases for the construction of offshore wind farms, which would be beneficial to the countries gearing toward a sustainable future such as the Philippines. This study presents the technical and economic viability of offshore wind farms in the Philippines. The analysis was divided into four phases, namely, application of exclusion criteria, technical analysis, economic assessment, and sensitivity analysis. Arc GIS 10.5 was used to spatially visualize the results of the study. Exclusion criteria were applied to narrow down the potential siting for offshore wind farms, namely, active submerged cables, local ferry routes, marine protected areas, reefs, oil and gas extraction areas, bathymetry, distance to grid, typhoons, and earthquakes. In the technical analysis, the turbines SWT-3.6-120 and 6.2 M126 Senvion were considered. The offshore wind speed data were extrapolated from 80 m to 90 m and 95 m using power law. The wind power density, wind power, and annual energy production were calculated from the extrapolated wind speed. Areas in the Philippines with a capacity factor greater than 30% and performance greater than 10% were considered technically viable. The economic assessment considered the historical data of constructed offshore wind farms from 2008 to 2018. Multiple linear regression was done to model the cost associated with the construction of offshore wind farms, namely, turbine, foundation, electrical, and operation and maintenance costs (i.e., investment cost). Finally, the levelized cost of electricity and break-even selling price were calculated to check the economic viability of the offshore wind farms. Sensitivity analysis was done to investigate how LCOE and price of electricity are sensitive to the discount rate, capacity factor, investment cost, useful life, mean wind speed, and shape parameter. Upon application of exclusion criteria, several sites were determined to be viable with the North of Cagayan having the highest capacity factor. The calculated capacity factor ranges from ~42% to ~50% for SWT-3.6-120 and ~38.56% to ~48% for 6.2M126 turbines. The final regression model with investment cost as the dependent variable included the minimum sea depth and the plant capacity as the predictor variables. The regression model had an adjusted R2 of 90.43%. The regression model was validated with existing offshore wind farms with a mean absolute percentage error of 11.33%. The LCOE calculated for a 25.0372 km2 offshore area ranges from USD 157.66/MWh and USD 154.1/MWh. The breakeven electricity price for an offshore wind farm in the Philippines ranges from PHP 8.028/kWh to PHP 8.306/kWh.

No longer monotypic: new species of the buccinoidean genera Germonea and Drepanodontus in the southwestern Atlantic (Gastropoda: Buccinidae)

New species of the until now monotypic buccinoidean genera Germonea and Drepanodontus are described from the southwestern Atlantic waters. These genera are only otherwise known from lower bathyal and abyssal depths of Scotia Sea. Germonea costulosa n. sp. collected near Namuncurá/Burdwood Bank in 681 to 785 m depth is the second known species of the genus characterized by distinctive regular ribs. In addition, Drepanodontus peonza n. sp., collected from the same area, is similar to the type species of this genus with two distinctive spiral cords along all whorls. The bathymetry of both new species is shallower than that of the already described species, at upper slope depths. Geographically the new species put both genera on both sides of the Antarctic convergence. Previous reports include D. tatyanae sharing this distribution rising some questions about the effectiveness of the Drake passage as a barrier.

გაზის ამოფრქვევები ზღვებსა და ოკეანეებში

Over the recent decades, gas and oil fields have been intensively explored in the seas and oceans of the world. As part of the expedition of the Ukrainian research ship "Professor Vodyanitsky", gas flows from the bottom of the Black sea of the continental shoal located on the territory of Georgia were studied. In this article, we conducted an environmental study of the results obtained during the expedition. The analysis revealed the dangers that gas emissions found in this region may pose. The article presents map of the coastal shelf of Adjara with gas release points; Similar places of gas emissions on the black sea coast of Crimea are discussed; The results of gas extraction in the Caspian sea are presented; The nature of environmental changes caused by the removal of a layer of hydrogen sulfide from the sea depths to the upper layers of the sea during a gas eruption is analyzed.

A Software Tool for the Design and Operational Analysis of Pressure Vessels used in Offshore Hydro-pneumatic Energy Storage

Despite the breakthroughs and rapid growth in the global installed offshore wind capacity over the last two decades, a prevailing major challenge is the intermittent nature of the wind resource itself. Consequently, co-locating energy storage systems with wind turbines deployed out at sea is perceived as a key component that will help to overcome this crucial challenge and address the mismatch between the supply of green energy and actual energy demand in real time. Of particular interest are hydro-pneumatic energy storage solutions that can deliver a safer and more reliable operation for a longer life span when compared to electro-chemical storage solutions.This paper presents a smart software tool named SmartPVB, which has been specifically developed for the optimisation of the design of pressure vessel bundles used in offshore hydro-pneumatic energy storage systems. The optimised design parameters obtained through the software SmartPVB help drive the material requirements to a minimum. A sensitivity study to analyse the influence of various parameters on a hydro-pneumatic energy storage system mounted on the seabed at a water depth of 200 m is also outlined. Results suggest that the optimal operating pressure ratio to minimise steel requirments for the pressure vessel bundle lies between 2.4 and 2.6. Furthermore, it is shown that the overall mass of the pressure vessel bundle per unit of storage capacity increases with sea depth, while it decreases with increasing peak operating pressures up to 200 bar.

A deep-sea bacterium related to coastal marine pathogens.

SummaryEvolution of virulence traits from adaptation to environmental niches other than the host is probably a common feature of marine microbial pathogens, whose knowledge might be crucial to understand their emergence and pathogenetic potential. Here, we report genome sequence analysis of a novel marine bacterial species, Vibrio bathopelagicus sp. nov., isolated from warm bathypelagic waters (3309 m depth) of the Mediterranean Sea. Interestingly, V. bathopelagicus sp. nov. is closely related to coastal Vibrio strains pathogenic to marine bivalves. V. bathopelagicus sp. nov. genome encodes genes involved in environmental adaptation to the deep‐sea but also in virulence, such as the R5.7 element, MARTX toxin cluster, Type VI secretion system and zinc‐metalloprotease, previously associated with Vibrio infections in farmed oysters. The results of functional in vitro assays on immunocytes (haemocytes) of the Mediterranean mussel Mytilus galloprovincialis and the Pacific oyster Crassostrea gigas, and of the early larval development assay in Mytilus support strong toxicity of V. bathopelagicus sp. nov. towards bivalves. V. bathopelagicus sp. nov., isolated from a remote Mediterranean bathypelagic site, is an example of a planktonic marine bacterium with genotypic and phenotypic traits associated with animal pathogenicity, which might have played an evolutionary role in the origin of coastal marine pathogens.

Bathymetry analysis with use of Sentinel-2 images

Bathymetry is described as Sea and Ocean depth measurements, and performed by many methods. Traditional methods, which are still used from the past to the present, have been replaced by modern methods with the development of technology. Sonar systems, LIDAR and remote sensing systems are listed as examples of these modern methods. The use of acoustic systems or LIDAR, are not economical in terms of both time and cost. In this study, remote sensing methods are investigated in order to minimize the time and cost. It is aimed to extract the information about bathymetry with use of free of charge satellite images. The method data used includes Sentinel-2 satellite images taken at different wavelengths and reference bathymetry values. Later, regression analyzes were made by using these data in band ratio and multi-band methods. By using the coefficients obtained by the regression analysis, the bathymetry estimation was made in places with unknown depth using the above methods without the need for reference depth.Band ratio and multi-band methods are used, and the results were evaluated. Bathymetric maps obtained from two methods were analyzed with the ground-truth values of the region and the amount of error was calculated. The highest accuracy was obtained from the ratio of blue band to green band. It has been observed that the red band has a disruptive effect.

Doubling of Group Velocity near the Coast due to Storm Surge, Tides or Tsunami: An Analytical Study

Tsunami may cause due to storm surge, earthquake at coastal region or at under the sea (obviously Hypocenter of earthquake must be within the earth’s crust or below). Each cases a wave packet which develops a set of simple harmonic motion of different wave lengths. These simple harmonic waves have been analyzed analytically. The velocity of propagation of waves depends upon the wave lengths. So the waves of nearly equal wave lengths can be considered as a group. This group of waves will propagate with nearly equal velocity which is known as group velocity. On considering two consecutive simple harmonic waves of same amplitude, we can find two equations describing simple harmonic motions having slightly different wave lengths and time periods. The combination of these two said SHM’s we can find another resultant SHM with different amplitude than of the previous two SHM’s. This new SHM has a slight variation in wave length and time period than that of that of the said earlier two SHM’s. Then using the perturbation technique on this resultant equation of SHM, we can find a new wave velocity (group velocity) in differential notation of wave velocity. This differential notation of wave velocity has been eliminated from the relation between the wave velocity on the surface of water and the depth of the sea. Then we get a relation between group velocity and wave velocity depending with depth of the sea. The application of boundary conditions on depth of deep sea and that of at the sea shore, we can find the group velocity at each region respectively. It is seen from the analysis that the group velocity at the sea shore is as much as double that of at the deep sea. Several recent cases of tsunamis or storm surges have been studied and it is found that the results depicted the same implementation through devastation that established by analytical study.

Feasibility of Offshore Wind Energy in Turkey; A Case Study for Gulf of Edremit at the Aegean Sea

This work aims to investigate the feasibility of offshore wind energy in Turkey by performing extensive simulations and analyses for a 50-90 MW capacity offshore wind park to be constructed at the Gulf of Edremit, a very high potential site located at the Aegean Sea, 3 km from the west coastline of Turkey. The location and layout of the farm is optimized by considering the sea depth data obtained from bathymetric maps and wind speed measurements acquired from the MERRA data and local met mast. Dynamic interactions among the turbines and the resulting wake losses are modeled by using two different site assessment programs. Capacity factors and the annual energy production yields are calculated for 8 different types of turbines with rated powers changing between 2 and 3.6 MW.

Pseudo-Direct-Drive Electrical Machine for a Floating Marine Turbine

The paper presents an investigation into the application of a magnetically geared Pseudo Direct Drive (PDD) electrical machine in a floating tethered 6kW, 100rpm marine current turbine. The turbine is designed to harness the energy from ocean currents, in regions with relatively high-speed water flows at depths that are a long distance from the seabed and cannot be economically exploited by conventional fixed turbines. The marine current turbine is a robust, easy to service and cost-effective solution for regions with variable or fixed sea depth of more than 60 metres. The paper presents the electromagnetic design and analysis of the PDD generator, and predicted performance such as efficiency, which is compared with dynamometer measurements on a prototype PDD generator. Furthermore, test results on a demonstrator marine turbine in a towing tank are also presented.