Direction Of Ocean Currents Research Articles

Optimizing Search and Rescue Strategies for Deep-Sea Submersibles Using the Monte Carlo Method

Deep-sea exploration is an important field where humans challenge the limits of nature. Improving its safety and efficiency is of great significance to deep-sea scientific research and resource development. In response to this, this study established a Monte Carlo-based motion model to predict the location of the crashed submersible. To truly simulate the distress environment of the submersible, this study introduced the Monte Carlo method to randomly generate 2,000 particles to reflect the uncertainty of the initial distress location, ocean current direction, and seawater density. Finally, it was combined with a six-degree-of-freedom kinematic model to generate All possible time-varying trajectories. This study also compared the effects before and after using the corresponding equipment and found that the equipment has a good effect on reducing uncertainties. This paper expands the field focused on floating objects on the sea surface to the search for underwater targets.

TWO-DIMENSIONAL FLOW PATTERN MODEL IN THE WATERS OF BAKAU BAY BINTAN DISTRICT

Ocean currents are the movement of sea water masses in a certain direction caused by several factors, namely wind, tides and bathymetry. Hydrodynamic modeling aims to determine the speed and direction of ocean currents in the waters of Bakau Bay through a two-dimensional model. The current pattern of the north season to the east season is influenced by sea water masses with an average current speed ranging from 0.22-0.24 m/s, while the south season to West season currents with an average speed of 0.04-0.26 m/s, this shows the meeting of different water masses so that the speed and direction of the current results in random or rotating currents. From the calculations of the normality test and anova test, it is known that the field current and model simulation values are normally distributed and there is no significant difference in values in the two data, so based on the RMSE value, it shows that the difference in values between the model simulation results and direct data measurements is relatively small. This also shows that the ocean surface current model created is sufficient to describe actual conditions.

U*: GA-based path planning algorithm for surface floating garbage cleaning robot

Marine debris is a serious global problem that is not limited to areas where humans live but also drifts around the world with wind and currents. More than 10 million tons of plastic waste flow into the ocean every year, posing a major threat to humanity. This study designs a path planning algorithm for surface garbage-cleaning robots called U*, which aims to improve the efficiency of salvaging marine debris and reduce labor and time costs. The U* algorithm consists of two procedures: exploration and path-planning. The exploration procedure searches for marine debris, while the path-planning procedure predicts the possible location of marine debris using the velocity and direction of ocean currents and finds the shortest path by using a genetic algorithm (GA) to collect the found marine debris. According to the experimental results, the U* method is more efficient in terms of reducing path length and time costs.

Design and analysis of underwater power generation characteristics of deflected double-stator switched reluctance generator

The Deflectable double-stator Switched Reluctance Generator (DSRG) has the advantages of simple structure, small volume and multi-dimensional operation. The DSRG and propeller are combined into the application of underwater power generation. With the help of the deflect ability of the generator, the efficiency is improved. Due to the uncertainty of ocean current direction and the structure of switched reluctance generator, the torque ripple is one of the important factors damaging the underwater generator. In order to effectively suppress the influence of torque ripple caused by generator operation, a method of adding pole shoes on the pole side of outer stator is proposed, so as to reduce the torque ripple. The propulsion structure running at different deflection angles is simulated. The torque and speed obtained before and after pole shoe optimization are input into the propeller model. The pressure and speed characteristics of the corresponding blade structure are simulated to verify the effect of optimization and the effectiveness of the power generation system.

Satellite Tracking of Head-Started Juvenile Green Turtles (Chelonia mydas) Reveals Release Effects and an Ontogenetic Shift

Juveniles of marine species, such as sea turtles, are often understudied in movement ecology. To determine dispersal patterns and release effects, we released 40 satellite-tagged juvenile head-started green turtles (Chelonia mydas, 1-4 years) from two separate locations (January and July 2023) off the coast of the Cayman Islands. A statistical model and vector plots were used to determine drivers of turtle directional swimming persistence and the role of ocean current direction. More than half (N = 22) effectively dispersed in 6-22 days from the islands to surrounding areas. The January turtles radiated out (185-1138 km) in distinct directions in contrast to the northward dispersal of the July turtles (27-396 km). Statistical results and vector plots supported that daily swimming persistence increased towards the end of tracks and near coastal regions, with turtles largely swimming in opposition to ocean currents. These results demonstrate that captive-reared juvenile greens have the ability to successfully navigate towards key coastal developmental habitats. Differences in dispersal (January vs. July) further support the importance of release timing and location. Our results inform conservation of the recovering Caymanian green turtles and we advise on how our methods can be improved and modified for future sea turtle and juvenile movement ecology studies.

Analysis of daily dynamics of thermal interaction of temperature and ocean flow in seaweed growth areas

Seaweed (Caulerpa sp) is a marine biota whose growth is influenced by physical parameters. The purpose of this study was to analyze the dynamics of daily temporal changes in seawater temperature at several depth points and variations in the velocity and direction of ocean currents. Make simple mathematical modeling of ocean current velocity and daily dynamics of seawater temperature in the seaweed growth zone and outside the seaweed growth area. Temperature measurements are carried out on 4 depth variations using a current meter when the sun illuminates the ocean. Measurement of the velocity and direction of the current is carried out using a current measuring instrument during the full moon. The Fourier function or periodic function determines mathematical modeling. The results showed that the transect measurement of sea temperature for 4 depth variations experienced changes due to the intensity of solar irradiation. During one cycle, the speed and direction of the ocean currents change periodically, with the average flow velocity in the seaweed zone being 7.4 m/min and outside the Lahe region being 18.75 m/min directly to the southwest at seawater flows at high tide and northeast experiencing low tide. The daily temporal change in ocean current velocity for each measurement transect shows the same shape which is modeled according to the Fourier function.

Distribution of Turbidity Values, Total Suspended Solids and Heavy Metals Pb, Cu in Tanah Merah Beach Waters and Semujur Island Waters, Bangka Tengah Regency

The high activity of tin (Sn) mining in the coastal areas of Bangka waters has an impact on turbidity, suspended solids, and increased levels of heavy metals (Pb, Cu). The study was conducted from February until April 2020 aims to determine the relationship between turbidity, total suspended solids (TSS), and concentrations of Pb and Cu in the Tanah Merah beach waters (TM) and Semujur Island waters (SM) which are characterized by the presence or absence of tin mining. (Sn) as a source of pollution. The results showed that the level of turbidity in TM (0.8-3.4 mg/l) was higher than in SM (0.4-0.8 mg/l) and Total Suspended Solid values in TM (149-185 mg/l) were lower than in SM (165-202 mg/l) and between (155-175 mg/l). The concentrations of heavy metals Pb in TM (0.05-0.09 mg/l) and Cu in TM (0.01-0.02 mg/l) were lower than in SM (Pb: 0.12-0.14 mg/l) and Cu (0.04-0.1 mg/l). Turbidity levels and high TSS values can be affected by the speed and direction of ocean currents. Heavy metals Pb and Cu are thought to be bound very effectively by TSS, their distribution is strongly influenced by the direction of the current and the velocity of the current formed.

Seasonal variation of marine debris at Manado Bay (North Sulawesi, Indonesia)

Marine debris has become a global concern due to its impact on marine ecosystems. These materials generally come from land and are deposited to marine environment through different agent of carrier. Many efforts are being made to monitor the dynamics of the debris including their presence and their variability in relation to seasons. The latter are assumed from the facts that the presence of the debris is mainly affected by the waves, speed, and direction of ocean currents in the area of interest. In this study, variation of debris in dry and wet season at Manado Bay was assessed by using a shoreline technique. Two locations are selected, Bailang and Malalayang beach. The samplings were conducted in August 2019 (represent dry season) and January 2020 (represent wet season). Several parameters are examined during the sampling; they are: amount of material, type of debris, composition, and spatial density of each type for macro-size (>2.5 cm) and meso-size (0.5–2.5 cm). The results showed that there was variation on composition and density, but the types of debris remain unchanged. Our present study concluded that variation in the season do not affect the variability of marine debris in Manado Bay.

Spatial and Temporal Distribution of Trace Metals in Shallow Marine Sedimentsof the Yucatan Shelf, Gulf of Mexico.

We investigated the spatial and temporal distribution of V and Cd in surface sediments of the Yucatan Shelf to establish current average values for the area. V and Cd concentrations are similar to those reported internationally for limestone rocks and surface marine sediments. The observed variability of V concentrations between cruises may be the result of changes in ocean current direction in summer (SW-S) and strong prevailing winds in autumn (N-NE). In addition to the hydrodynamics described above, Cd variations may also be associated with inputs of particulate material by upwelling events and subsequent transport and distribution to the shelf by the Yucatan Channel current (autumn). Considering that both metals showed significant spatial and temporal differences, a range of values for V (0.4-1.5µgg-1) and Cd (0.05-0.2µgg-1) are proposed as baseline reference for sediments of the Yucatan Shelf.

Gaps Filling in HF Radar Sea Surface Current Data Using Complex Empirical Orthogonal Functions

The knowledge of speed and direction of coastal ocean currents are critical for carrying out search and rescue at sea, to respond to the hazardous marine oil spills, to estimate the dispersal pattern of pollutants, to issue warnings against tsunamis and cyclones etc. Such operations need uninterrupted observational data of sea surface currents over wide area with high spatial and temporal resolution. The High frequency (HF) radars installed at the shore, sense the surface of ocean using electromagnetic waves, and provide the speed and direction of ocean currents over a specific spatial domain at high temporal resolution. However, the frequent gaps in the data are a concern for its usage. The gaps arise due to its dependence on the roughness of the sea other electromagnetic interferences from environment sources and due to data acquisition failures. Hence, it is necessary to fill the gaps for successful usage of HF radar data. The present work describes a method to fill the gaps in the HF radar data using complex empirical orthogonal functions (CEOF). Before filling the missing data, HF radar data is assessed with available observations. The CEOFs are calculated iteratively using singular value decomposition. The number of statistically significant CEOFs required to construct the missing HF radar currents data accurately along the Indian coast are obtained through a cross-validation procedure. The proposed method is first validated for various rates of synthetic data gaps created in synthetic data and in model derived cyclonic wind fields and comparisons are illustrated, the reconstructed data and the original data are in good match

HY-1C Observations of the Impacts of Islands on Suspended Sediment Distribution in Zhoushan Coastal Waters, China

We analyzed the impacts of islands on suspended sediment concentration (SSC) in Zhoushan Coastal waters based on data from HY-1C, which was launched in September 2018 in China, carrying Coastal Zone Imager (CZI) and Chinese Ocean Color and Temperature Scanner (COCTS) on it for offshore observation. A new SSC retrieved model was established based on the relationship between in situ SSC and the reflectance in red and near infrared bands of CZI image. Fifteen CZI images obtained from October to December 2019 were applied to retrieve SSC in Zhoushan coastal waters. The results show that SSC in study area is 100–1600 mg·L−1. The SSC near islands changes obviously. Upstream of the islands, SSC is lower than downstream. During the flood and ebb, when the current passes through the islands, circumfluence will appear, under certain geophysical factors, generating Karman vortex streets downstream of the islands. The sediments were stirred by the fast speed current at the outer side of vortex street to the sea surface inducing higher SSC at the outer side of the vortex street, while the central sediments of the vortex street were lower. In the direction of ocean currents, the SSC of the vortex street downstream of islands is changing regularly, i.e., increasing, then decreasing and increasing again and then decreasing in a snaking vortex street whose length downstream is between 1000 and 8000 m long.

Real-time Reconstruction of Surface Velocities from Satellite Observations in the Alboran Sea

Surface currents in the Alboran Sea are characterized by a very fast evolution that is not well captured by altimetric maps due to sampling limitations. On the contrary, satellite infrared measurements provide high resolution synoptic images of the ocean at high temporal rate, allowing to capture the evolution of the flow. The capability of Surface Quasi-Geostrophic (SQG) dynamics to retrieve surface currents from thermal images was evaluated by comparing resulting velocities with in situ observations provided by surface drifters. A difficulty encountered comes from the lack of information about ocean salinity. We propose to exploit the strong relationship between salinity and temperature to identify water masses with distinctive salinity in satellite images and use this information to correct buoyancy. Once corrected, our results show that the SQG approach can retrieve ocean currents slightly better to that of near-real-time currents derived from altimetry in general, but much better in areas badly sampled by altimeters such as the area to the east of the Strait of Gibraltar. Although this area is far from the geostrophic equilibrium, the results show that the good sampling of infrared radiometers allows at least retrieving the direction of ocean currents in this area. The proposed approach can be used in other areas of the ocean for which water masses with distinctive salinity can be identified from satellite observations.

Contrasting molecular diversity and demography patterns in two intertidal amphipod crustaceans reflect Atlantification of High Arctic

The distribution of two common intertidal amphipod species Gammarus oceanicus and Gammarus setosus was studied along the coast of Svalbard Archipelago. Genetic analysis showed geographical homogeneity of G. oceanicus with only one molecular operational taxonomic unit (MOTU) and much higher diversification of G. setosus (5 MOTUs) in the studied area. Only two MOTUs of G. setosus are widespread along the whole studied Svalbard coastline, whereas the remaining three MOTUs are present mainly along the northern and eastern parts of archipelago’s largest island, Spitsbergen. Distribution analysis indicates that the demographic and spatial expansion of G. oceanicus in the northern Atlantic has started already during the Last Glacial Maximum (LGM, ca. 18 ka), while G. setosus seems to be a long-persistent inhabitant of the Arctic, possibly even through the LGM, with slower distribution dynamics. Combining the results of our molecular study with previous field observations and the knowledge upon the direction of ocean currents around the Svalbard Archipelago, it can be assumed that G. oceanicus is a typical boreal Atlantic species that is still continuing its postglacial expansion northwards. In recent decades it colonized High Arctic due to the climate warming and has partly displaced G. setosus, that used to be the only common gammarid of the Svalbard intertidal zone.

Study of Distribution Metal From Shellfish at Coastal Beach in District of Central Tapanuli, Indonesia

The research of heavy metals spread in shellfish in the coastal area a zone of the high seas and zones of settlements waters in Central Tapanuli has done with the aim of knowing the content of heavy metals of Cu, Cr, Pb with parameters of the river water, sea water, shellfish and clamshell, basic sediments. Testing of river water, sea water, and shell meat was conducted using Atomic Absorption Spectrometer (AAS) by adsorption principle of light by atoms. Testing basic sediment and clamshell has done with XRD and TEM. The test results of river water showed are Cu ˂0,025 mg/l, Cr ˂0.006 mg/l - ˂0.025 mg/l, Pb ˂0.005 to 0.03 mg/l, in the conditions of under the river water quality standard. The test results on the sea water obtained are metal content of Cu. ˂0.006 mg/l, Cr ˂0,025 mg/l, Pb 0.13 to 0.24 mg/l. The test results show the shell meat are Pb. ˂0.005 to 2.34 mg/kg, Cu 0.85 to 14.4 mg/kg. The test results of clamshell with XRD showed peaks of CaCO3 aragonite. With TEM showed that crystalline, by electron diffraction pattern formed by irregular dot, which means the elements contained in the various clamshells. Differences levels of heavy metals at every point stations predicted has their natural factors such as the direction of ocean currents, rainfall and sediment material and anthropogenic factors such as demographics residential waste pollution, industrial and port activity.

Гидроакустическое оборудование автономных подводных профилирующих аппаратов

Autonomous underwater profilers are designed for measurements of vertical profiles of ocean currents and marine environmental parameters. Such device moves along a vertically stretched cable at the buoy stations. Generally, a profiler comprises convenient platform for mounting of hydroacoustic equipment. A suit of sensors installed at the profiler carries out the measurements in the water column from the near-surface layer to the bottom allowing a researcher to obtain uniform data with the same accuracy. During the survey, the device usually maintains a stable orientation relative to the direction of flow, which is important for acoustic Doppler measurements of the speed and direction of ocean currents. This paper deals with applications of the moored automatic mobile profiler Aqualog for underwater communication and data transmission, acoustic measurements of the flow velocity and small-scale inhomogeneities.

A Three-Dimensional Model for the Seabed Response Induced by Waves in Conjunction with Currents in the Vicinity of an Offshore Pipeline Using OpenFOAM

To better understand the physical processes involved in the wave–seabed–pipeline interactions (WSPI), a three-dimensional numerical model for the wave-induced soil response around an offshore pipeline is proposed in this paper. Seabed instability around an offshore pipeline is one of the key factors that need to be considered by coastal engineers in the design of offshore infrastructures. Most previous investigations into the problem of WSPI have only considered wave conditions and have not included currents, despite the co-existence of waves and currents in natural ocean environments. Unlike previous studies, currents are included in the present study for the numerical modeling of WSPI, using an integrated FVM model, in which the volume-averaged Reynolds-averaged Navier–Stokes (VARANS) equation is used to solve the mean fluid field, while Biot’s consolidation equation is used to describe the solid–pore fluid interaction in the porous medium. Numerical examples demonstrate a significant influence of ocean current direction and angle on the wave-induced pore pressures and the resultant seabed liquefaction around the pipeline, which cannot be observed in two-dimensional (2D) numerical simulation.

Navigating the ‘broad freeway’: ocean currents and inland isolation drive diversification in the Pandanus tectorius complex (Pandanaceae)

AbstractAimTo test for and describe the genetic structure of the Pandanus tectorius complex, a group of closely related ocean‐dispersed plants and members of the Indo‐Pacific coastal strand community.LocationTropical Indo‐Pacific (coastal East Africa to Polynesia).MethodsWe sampled 535 individuals (46 localities) from throughout the range of the complex. Fifteen microsatellite loci were used to detect and characterize population structure and estimate migration rates between island groups and broad regions.ResultsHierarchical population structure was detected. Samples group into an eastern cluster (Hawaii and coastal South‐Central Pacific localities) and a western cluster [Western Pacific (WP) through Indian Ocean]. Within these two clusters, at least six regional subclusters were detected including samples from the Indian Ocean + South China Sea (SCS), Ogasawara Islands, WP, inland South‐Central Pacific, coastal South‐Central Pacific and Hawaii. Migration rates between regions are low leading to isolation and genetic differentiation while within regions, rates are much higher. In most cases, inland populations are genetically differentiated from nearby coastal counterparts.Main conclusionsSubstantial population structure occurs across the range of the P. tectorius complex due to dispersal limitation across stretches of open ocean and patterns of ocean currents. Low levels of asymmetric westward migration, consistent with the direction of ocean currents in the Pacific, links Hawaii and the South‐Central Pacific with populations further to the west preventing complete isolation. SCS + Indian Ocean populations are distinct from those in the Pacific due to limited dispersal between these regions. The isolation of inland populations on several islands also contributes to genetic differentiation. While population clusters have a clear geographical basis they are not completely congruent with previously recognized taxa.

Estimating behavior in a black box: how coastal oceanographic dynamics influence yearling Chinook salmon marine growth and migration behaviors

Ocean currents or temperature may substantially influence migration behavior in many marine species. However, high-resolution data on animal movement in the marine environment are scarce; therefore, analysts and managers must typically rely on unvalidated assumptions regarding movement, behavior, and habitat use. We used a spatially explicit, individual-based model of early marine migration with two stocks of yearling Chinook salmon to quantify the influence of external forces on estimates of swim speed, consumption, and growth. Model results suggest that salmon behaviorally compensate for changes in the strength and direction of ocean currents. These compensations can result in salmon swimming several times farther than their net movement (straight-line distance) would indicate. However, the magnitude of discrepancy between compensated and straight-line distances varied between oceanographic models. Nevertheless, estimates of relative swim speed among fish groups were less sensitive to the choice of model than estimates of absolute individual swim speed. By comparing groups of fish, this tool can be applied to management questions, such as how experiences and behavior may differ between groups of hatchery fish released early vs. later in the season. By taking into account the experiences and behavior of individual fish, as well as the influence of physical ocean processes, our approach helps illuminate the “black box” of juvenile salmon behavior in the early marine phase of the life cycle.

AFSAOCP: A novel artificial fish swarm optimization algorithm aided by ocean current power

Artificial Fish Swarm is a kind of swarm intelligence algorithm, which focuses on the behavior of individual fishes and information interactions among them during foraging and preying on something in real environment. A novel Artificial Fish Swarm Optimization Algorithm Aided by Ocean Current Power (abbreviation for AFSAOCP) is proposed, which assumes the ocean current always causes certain influence on the fishes’ activity speed. Firstly, the computing model of ocean current is developed and constructed. Then the influence level of the ocean current on fishes is analyzed. If fishes are swimming along ocean current direction, ocean current will drive fishes’ speed increment, which is called positive influence; if fishes are swimming against ocean current, the current will hinder the fishes’ speed, which is called negative influence. In addition, fishes’ speed is not influenced by the ocean current, which is called merits offset faults. To sum this up, fishes in each group have different speed range, respectively. Grouping strategies can not only increase species diversity, but it can also make the algorithm escape from local optimal value in the iteration process. The proposed variant, AFSAOCP, is examined on several widely used benchmarked functions, and the experimental results show that the proposed AFSAOCP algorithm improves the existing performance of other algorithms when dealing with the different dimension and multimodal problems.

The Structure of Genetic Diversity in Eelgrass (Zostera marina L.) along the North Pacific and Bering Sea Coasts of Alaska.

Eelgrass (Zostera marina) populations occupying coastal waters of Alaska are separated by a peninsula and island archipelago into two Large Marine Ecosystems (LMEs). From populations in both LMEs, we characterize genetic diversity, population structure, and polarity in gene flow using nuclear microsatellite fragment and chloroplast and nuclear sequence data. An inverse relationship between genetic diversity and latitude was observed (heterozygosity: R2 = 0.738, P < 0.001; allelic richness: R2 = 0.327, P = 0.047), as was significant genetic partitioning across most sampling sites (θ = 0.302, P < 0.0001). Variance in allele frequency was significantly partitioned by region only in cases when a population geographically in the Gulf of Alaska LME (Kinzarof Lagoon) was instead included with populations in the Eastern Bering Sea LME (θp = 0.128–0.172; P < 0.003), suggesting gene flow between the two LMEs in this region. Gene flow among locales was rarely symmetrical, with notable exceptions generally following net coastal ocean current direction. Genetic data failed to support recent proposals that multiple Zostera species (i.e. Z. japonica and Z. angustifolia) are codistributed with Z. marina in Alaska. Comparative analyses also failed to support the hypothesis that eelgrass populations in the North Atlantic derived from eelgrass retained in northeastern Pacific Last Glacial Maximum refugia. These data suggest northeastern Pacific populations are derived from populations expanding northward from temperate populations following climate amelioration at the terminus of the last Pleistocene glaciation.