Search

A wave–current coupled numerical model with 3D radiation stress formalism is used to study baroclinic effects, specifically stratification and baroclinic pressure gradient force (BcPGF), on wind-wave-driven flows, separated as vertically sheared flows and vertically homogeneous flows. Numerical experiments are conducted under ideal offshore winds of 8 m s−1. Results show that stratification enhances the two-layer structure of the wave-driven sheared flow, while BcPGF has minimal impact. Stratification and BcPGF have limited influence on the direction of the wave-driven depth-averaged circulation, but they can enhance the total circulation by promoting the upper one. In the upper layer where form drag dominates, the competition between the vertical form drag divergence (FDD) and turbulent stress divergence (TSD) plays a critical role in shaping the wave-driven flow. Stratification reduces vertical eddy viscosity Km, suppressing the growth of TSD associated with the vertical shear of velocity, which facilitates the FDD driving the upper outflow. Likewise, stratification can enhance the effect of FDD curl on the upper horizontal circulation by limiting the growth of TSD curl related to the vertical shear of vorticity. Additionally, low Km reinforces geostrophic effect and therefore enhances the lateral circulation. Baroclinic torque contributes to reducing the vertical variation of vorticity and the growth of TSD curl, indirectly improving the effectiveness of FDD curl in driving the upper circulation. Stratification undergoes fortnightly adjustments due to the spring–neap cycle, leading to the synchronized variation in the strength of wave-driven flow, particularly its vertically sheared component. During neap tides with weak tidal forcing and well-developed stratification, wave-driven sheared flow, horizontal circulation, and lateral circulation are stronger. Significance Statement: The aim of this study is to enhance our comprehension of the impact of baroclinic processes on wind-wave-driven flows in wind-dominated regimes. During summer, wave-driven flows exhibit noticeable vertical shearing, which differ from those observed in winter. This is particularly important because during summer, river runoffs generate strong stratification and introduce large quantities of terrigenous materials into coastal oceans. Consequently, wave-driven flows may play a crucial role in bay-shelf exchange, which has been given in few studies. Our findings highlight the influence of baroclinic processes on turbulent stress divergence, which can enhance wave-driven flows, both the vertically sheared and the vertically homogeneous components, especially during neap tides. [ABSTRACT FROM AUTHOR]

X-band marine radar captures the signal reflected from the sea surface. Theoretical studies indicate that the initial unfiltered signal contains meaningful information about wind wave parameters. Traditional methods of significant wave height (SWH) estimation rely on physical laws describing signal reflection from rough surfaces. However, recent studies suggest the feasibility of employing artificial neural networks (ANNs) for SWH approximation. Both classical and ANN based approaches necessitate costly in situ data. In this study, as a viable alternative, we propose generating synthetic radar images with specified wave parameters using Fourier-based approach and Pierson- Moskowitz wave spectrum. We generate synthetic images and use them for unsupervised learning approach to train a convolutional component of the reconstruction ANN. After that, we train the regression ANN based on the previous convolutional part to obtain SWH back from the synthetic images. Then, we apply preliminary trained weights for the regression model to train SWH approximation on the dataset of real sea clutter images. In this study, we demonstrate the increase in SWH estimation accuracy from radar images with preliminary training on synthetic data. [ABSTRACT FROM AUTHOR]

This study presents a state-of-the-art risk evaluation approach, designed for spatiotemporal multivariate environmental dynamic wind-wave systems, being either measured or Monte Carlo (MC) numerically simulated over a representative time-lapse. The main objective of this study has been to benchmark/validate the effectiveness and accuracy of the Gaidai multivariate risk evaluation methodology, using the application to in situ raw windspeeds, along with correlated wave-heights measurements, delivered by North Pacific area of the National Oceanic and Atmospheric Administration (NOAA) ocean buoys. The current study outlines a novel risk evaluation methodology, suitable for environmental dynamic systems, that are either MC numerically modeled, or directly physically measured. The intercorrelations between the wind-wave environmental system's critical/key dimensions and components, along with the high dimensionality of complex environmental systems, are not easily addressed by contemporary classic reliability methods. The objective of this study is to apply a novel reliability/risk evaluation methodology to a combined windspeed and correlated wave-height raw data set, recorded by the NOAA buoys within the North Pacific area, to demonstrate the efficiency of the proposed methodology. By reliability/risk assessment in the current study authors primarily mean probability forecast of certain multivariate hazard event. It is well known that when combined, windspeeds along with correlated wave heights form nonlinear dynamic environmental systems, that are complex, multidimensional, nonstationary, and yet intercorrelated. Global warming is only one of several significant factors that have ongoing impact on ocean windspeeds along with correlated wave heights, and environmental system risk evaluation is essential for marine, naval, and offshore structures, operating within specific in situ offshore areas of interest subject to realistic in situ ocean/sea weather conditions. The main goal of this study had been to benchmark and validate novel multivariate risk analysis methodology, making it possible to extract essential information directly from in situ raw environmental measurements. The methodology presented in this study opens the possibility of efficiently yet accurately assessing global failure/damage and hazard risks for multivariate nonstationary nonlinear environmental sea/ocean wind-wave systems. [ABSTRACT FROM AUTHOR]

Offshore wind turbines (OWTs) often operate in complex marine environments, where they are not only subjected to wind and wave loads, but also adversely affected by scour. Therefore, it is of great significance to explore the effect of scour on the dynamic responses of OWTs under external loads to ensure structural safety, improve performance, and extend service life. In this study, a comprehensive numerical model of a 5-MW OWT, including tower, monopile, and soil-structure interaction (SSI) systems, is established by using ABAQUS platform. Aerodynamic loads is generated using blade element momentum, while wave loads is generated using the P-M spectral. The depth of scour is obtained based on on-site measured data. A comparative analysis is conducted between fixed foundations and SSI systems when conducting dynamic response analysis of OWTs under wave loads. Subsequently, the effect of scour on dynamic responses of OWTs under aerodynamic and wave loads is investigated. Results demonstrate that SSI can significantly influence the natural frequency and dynamic responses of the OWT. Therefore, it is essential to thoroughly consider SSI when evaluating the dynamic response of the OWT with local scour. The tower-top displacement and acceleration of the OWT with show a significant increasing trend compared to the non-scoured OWT. An increase in scour depth leads to higher maximum stress and stress amplitude in the steel monopile, which could potentially cause fatigue issues and should be given due attention. [ABSTRACT FROM AUTHOR]

The propagation and dissipation of typhoon-induced surface waves are vital to morphological evolution and related engineering within coastal and estuarine regions. An observation system was operated during Typhoon Higos, and TELEMAC--TOMAWAC numerical modeling was performed for Typhoons Hagupit, Hato, and Higos along the central coast of Guangdong and the Pearl River Estuary in China to explore variations in wave propagation and dissipation during typhoons. The results showed that wind waves were dominant before typhoon landfall, and the intense wind waves dissipated rapidly during typhoon decay, while they could stay longer within the estuarine regions. Landward wave propagation had a tendency to convert from being convergence-dominated to being dissipation-dominated with the morphological change and tended to converge at the mouth-bar region. Within the estuarine regions, waves dissipated more rapidly at the prismatic estuary than at the bell-shaped bays due to the limited width and rapid contraction of the outlet. Moreover, the track and scale of typhoons had critical effects on the generated wave field, and they dominated the intensity, propagation, and dissipation of the overall wave field. Specifically, typhoons with broader scales and longer moving tracks within the coastal regions of Guangdong Province enhanced the wind--wave interaction and induced a stronger and wider wave field, despite that their typhoon intensities were comparable (i.e., Hagupit vs. Hato). Furthermore, waves generated by compact and regular cyclone structures dissipated more strongly along the moving track of typhoons (i.e., Hato and Higos). Except for typhoons directly attacking the Pearl River Estuary, waves within the estuarine regions tended to dissipate/converge when located on the right/left side of the moving track of typhoons. [ABSTRACT FROM AUTHOR]

The article in the Journal of Fluid Mechanics delves into the influence of mean water current on wind wave development in a controlled laboratory environment. It examines how statistical parameters of wind-generated waves are affected by the presence of water flow, impacting factors like energy, frequency, and coherence. The research also delves into the dispersion relation for gravity-capillary waves in the presence of uniform current, offering valuable insights for coastal engineering and physical oceanography. By studying the combined effects of wind and current on water waves, the study sheds light on the intricate interactions that shape wave evolution and characteristics. [Extracted from the article]

The article "Evolution of water wave packets by wind in shallow water" explores the use of the Korteweg– de Vries (KdV) equation to study wind-driven water wave packets in shallow water. It discusses the impact of forcing/friction terms on wave growth and decay, utilizing the Whitham modulation theory to predict these rates. Numerical simulations validate the theoretical predictions, highlighting the formation of solitary waves and the emergence of a soliton gas in various scenarios. The study provides insights into the evolution of water wave packets by wind in shallow water, shedding light on the complex dynamics involved. [Extracted from the article]

Owing to the simplification of the wind turbine, it is difficult to accurately simulate the interaction between the rotor system and the supporting structure using the decoupling finite element method. Therefore, when using this method for safety assessment and dynamic response research of the offshore wind turbine (OWT), there is a deviation between the simulation result and the real response of the OWT. In this study, an improved decoupled finite element analysis method is proposed based on a theoretical derivation. A simplified finite element model of a 10 MW jacket OWT with an equivalent substructure was established, and the dynamic response of the OWT under wind and waves was studied. By comparing the results of the fully coupled analysis method and the traditional finite element method, the applicability of the traditional finite element analysis method to the dynamic analysis of an OWT under typical winds and waves is discussed. The limitations of using the traditional finite element method to study or evaluate an OWT complex dynamic system were revealed, and the effectiveness and applicability of the improved method proposed in this study were qualitatively and quantitatively verified. Subsequently, based on the proposed improved decoupled finite element analysis method, a numerical calculation corresponding to a fully coupled test was performed. Compared with the numerical results obtained by the traditional finite element method, the improved decoupled finite element method proposed in this study obtained more consistent results with the fully coupled test. [ABSTRACT FROM AUTHOR]

This paper proposes a shore-based constant tension mooring system, which improves the cable tension distribution by adjusting the length of the cable to maintain the constant tension of the cable between the ship and the mooring pile in order to solve the problem of poor safety and reliability of the traditional mooring system in the mooring process. First, based on the three-dimensional potential flow theory, this paper uses the hydrodynamic software AQWA to numerically simulate the dynamic response of the traditional mooring system under the coupling of wind, wave, and current in different sea states. Subsequently, a shore-based constant tension mooring system using the principle of volume-varying hydraulic control was studied. On the basis of a comprehensive analysis of the working principle of the constant tension hydraulic control mooring system, a mathematical model of the main working circuit is established. The system was numerically simulated by relying on matlab/Simulink simulation software. Finally, by comparing with traditional mooring systems, the results show that the maximum cable tension of the shore-based constant tension mooring system is significantly reduced so that the tension is controlled within a fixed range, and the safety factor of the mooring cable is significantly improved, thus reducing the risk of mooring system failure and improving the ship's survivability. [ABSTRACT FROM AUTHOR]

When estimating significant wave height and wave power, it is regularly assumed 4 for the spectral estimate factor. It means considering a narrowband wave spectrum. That approach is accurate enough when the spectral broadness parameter is near zero. Since the Peru Basin is an open ocean: swells and local wind waves can overlap; therefore, its wave spectrum should be considered broadband. This work aims to demonstrate that the wave spectrum in the Peru Basin has waves in a broad band of frequencies and also discuss how this characteristic affects estimating the significant wave height and wave power. The methodology comprises numerical methods, inferential statistics, and spectral analysis applied to ocean data. The paper's conclusions declare the Peru Basin wave spectrum as broadband. The estimated significant wave height for broadband wave spectrum is 7% lower than if the wave spectrum was considered narrowband. We propose 3.7 as the spectral estimate factor for calculating the significant wave height in the Peru Basin instead of the commonly used 4. The significant wave height error when assuming a narrowband wave spectrum slightly affects the spectral parametric wave power calculation, causing a maximum overestimation of 5%. Nevertheless, accurately estimating significant wave height is critical for diverse marine technologies. [ABSTRACT FROM AUTHOR]

In inland waterways, waves generated by passing boats cause the movement of riprap used for bank protection and stabilization. Previous studies have mainly concerned the natural channel erosion problem caused by wind-generated waves and neglected the research and findings on shipping behavior. This work presents a coupling of the computational fluid dynamics model and the discrete element method. The aim is to first study the interactions between ship waves in the confined channel and the movements of the riprap of the banks and shorelines and second to analyze the stability of these armourstones under the actions of various ship velocities and draught depths. These varying conditions exert influence on the ship-induced waves, the crucial point being the drawdown amplitude, and consequently create more intense flow behavior in the near-shore region, which results in instability and destruction of the overall structure of the armor protection layer. The higher ship velocity and the larger draught depth lead to the aggravation of instability processes of the blocs composing the protective layer. There is a critical phenomenon in the influence mechanism of vessel velocity, whereas the variation process induced by draught depth is relatively linear. In addition, the stability of the blocs also depends on their shapes, sizes, and the initial positions within the protective layer. This study could contribute to the high-quality development of inland navigation. [ABSTRACT FROM AUTHOR]

A third-generation wave model is driven by the synthetic wind field combined with the revised Holland wind and surface wind product from the National Centers for Environmental Prediction (NCEP). The temporal and spatial characteristics of the wind waves and swell during the typhoon are studied, as well as the responses of their wave energy spectra to the source terms. The results show that the typhoon waves have a more complicated asymmetric structure than the wind field, and the maximum significant wave height is always located on the right side of the direction along which the typhoon is moving, where wind waves are dominant, due to the extended fetch. The nonlinear wave–wave interaction helps to redistribute the energy of the wind seas at a high frequency to the remotely generated swells at a low frequency, ensuring that the typhoon wave's energy spectrum remains unimodal. This process occurs in regions without extended fetch, and a similar continued downshift in frequency as the wave–wave interaction occurs for the wind input as well when the waves outrun the typhoon, due to the nonlinear coupling between the wind and growing swells. [ABSTRACT FROM AUTHOR]

Numerical prediction of the interactions between wind and ocean waves is essential for climate modeling and a wide range of offshore operations. Large Eddy Simulation (LES) of the marine atmospheric boundary layer is a practical numerical predictive tool but requires parameterization of surface fluxes at the air–water interface. Current momentum flux parameterizations primarily use wave-phase adapting computational grids, incurring high computational costs, or use an equilibrium model based on Monin–Obukhov similarity theory for rough surfaces that cannot resolve wave phase information. To include wave phase-resolving physics at a cost similar to the equilibrium model, the MOving Surface Drag (MOSD) model is introduced. It assumes ideal airflow over locally piece-wise planar representations of moving water wave surfaces. Horizontally unresolved interactions are still modeled using the equilibrium model. Validation against experimental and numerical datasets with known monochromatic waves demonstrates the robustness and accuracy of the model in representing wave-induced impacts on mean velocity and Reynolds stress profiles. The model is formulated to be applicable to a broad range of wave fields and its ability to represent cross-swell and multiple wavelength cases is illustrated. Additionally, the model is applied to LES of a laboratory-scale fixed-bottom offshore wind turbine model, and the results are compared with wind tunnel experimental data. The LES with the MOSD model shows good agreement in wind–wave–wake interactions and phase-dependent physics at a low computational cost. The model's simplicity and minimal computational needs make it valuable for studying turbulent atmospheric-scale flows over the sea, particularly in offshore wind energy research. [ABSTRACT FROM AUTHOR]

Bubble plumes play a significant role in the air–sea interface by influencing processes such as air–sea gas exchange, aerosol production, modulation of oceanic carbon and nutrient cycles, and the vertical structure of the upper ocean. Using acoustic Doppler current profiler (ADCP) data collected off the west coast of Ireland, we investigate the dynamics of bubble plumes and their relationship with sea state variables. In particular, we describe the patterns of bubble plume vertical extension, duration, and periodicity. We establish a power-law relationship between the average bubble penetration depth and wind speed, consistent with previous findings. Additionally, the study reveals a significant association between whitecapping coverage and observed acoustic volume backscatter intensity, underscoring the role of wave breaking in bubble plume generation. The shape of the probability distribution of bubble plume depths reveals a transition toward stronger and more organized bubble entrainment events during higher wind speeds. Furthermore, we show that deeper bubble plumes are associated with turbulent Langmuir number Lat ∼ 0.3, highlighting the potential role of Langmuir circulation on the transport and deepening of bubble plumes. These results contribute to a better understanding of the complex interactions between ocean waves, wind, and bubble plumes, providing valuable insights for improving predictive models and enhancing our understanding of air–sea interactions. Significance Statement: This research contributes to understanding bubble plume dynamics in the upper ocean and their relationship with sea state variables. The establishment of a power-law relationship between the bubble penetration depth and wind speed, along with the association between whitecapping coverage and acoustic backscatter intensity, contributes to improved predictive capabilities for air–sea interactions and carbon dioxide exchange. The identification of the potential influence of Langmuir circulation on bubble plume dynamics expands our understanding of the role of coherent circulations in transporting bubble plumes. Additionally, this study presents a clear methodology using commercial sensors such as an ADCP, which can be easily replicated by researchers worldwide, leading to potential advancements in our comprehension of bubble plume dynamics. [ABSTRACT FROM AUTHOR]

The request for quickly available forecasts of intense weather and marine events impacting coastal areas is gradually increasing. High-performance computing (HPC) and artificial intelligence techniques are crucial in this application. Risk mitigation and coastal management must design scientific workflow appropriately and maintain them continuously updated and operational. Climate change accelerating increase trend of the past decades impacted on sea-level rise, together with broader factors such as geostatic effects and subsidence, reducing the effectiveness of coastal defenses. Due to this, the support tools, such as Early Warning Systems, have become increasingly more valuable because they can process data promptly and provide valuable indications for mitigation proposals. We developed the Shoreline Alert Model (SAM), an operational Python tool that produces simulation scenarios, 'what-if' assumptions, and coastal flooding forecasts to fill this gap in our study area. SAM aims to provide decision-makers, scientists, and engineers with new tools to help forecast significant weather-marine events and support related management or emergency responses. SAM aims to fill the gap between the wind-driven wave models, which produce simulations and forecasts of waves of significant height, period, and direction in deep or mid-water, and the run-up local models, which exstimulate marine ingression in the event of intense weather phenomena. It employs a parallelization scheme that allows users to run it on heterogeneous parallel architectures. It produced results approximately 24 times faster than the baseline when using shared memory with distributed memory, processing roughly 20,000 coastal cross-shore profiles along the coastline of the Campania region (Italy). Increasing the performance of this model and, at the same time, honoring the need for relatively modest HPC resources will enable the local manager and policymakers to enforce fast and effective responses to intense weather phenomena. [ABSTRACT FROM AUTHOR]

In order to study the dynamic response of offshore platforms in complex marine environments (combined action of wind, wave and current loads), the offshore jacket platform model was established by using finite element software, the strength of its ultimate load structure was checked, and different working conditions were simulated and analyzed to grasp its dynamic response characteristics and rules, and finally its fatigue life was predicted by combining with S-N curve. The results show that the natural vibration period of the jacket structure is much smaller than the wave period, and the resonance basically does not occur. Under the extreme storm, the strength and stiffness of the jacket structure meet the requirements, and with the increase of wave height and wave velocity, the maximum equivalent stress and maximum displacement are significantly improved, the maximum stress increases by more than 182.76%, and the displacement increases by more than 182.72%, and the maximum stress area occurs at the intersection of the diagonal brace support. The fatigue life of the jacket structure is predicted to be 44.19 years, which meets the design requirements. [ABSTRACT FROM AUTHOR]

This study examines the impact of wave-induced processes (WIPs) in modulating thermosteric sea-level changes, highlighting the need to include these processes in future sea-level rise assessments and climate projections. The impact of wave-induced processes on thermosteric sea-level changes is investigated using coupled ocean-wave simulations. These simulations include the effects of Stokes-Coriolis forcing, sea-state dependent surface stress and energy fluxes, and wave-induced mixing. The experiments use a high-resolution configuration of the Geesthacht COAstal Model SysTem (GCOAST), covering the Northeast Atlantic, the North Sea and the Baltic Sea. The GCOAST system uses the Nucleus for European Modelling of the Ocean (NEMO) ocean model to account for wave-ocean interactions and ocean circulation. It is fully coupled with the WAM spectral wind wave model. The aim is to accurately quantify the sea state contribution to thermosteric sea level variability and trends over a 26-year period (1992–2017). The ability of wave-ocean coupled simulations to reveal the contribution of sea state to sea level variability and surge is demonstrated. It is clear that wave-induced processes (WIPs) play a significant role in sea surface dynamics, ocean mixing (mixed layer thickness) and modulation of air-sea fluxes (e.g. heat flux) in both winter (10–20%) and summer (10%), which in turn affect thermosteric sea level variability. The North Atlantic (in summer) and the Norwegian Trench (in winter) show significant contributions (40%) to the thermosteric sea-level variability due to wave-induced processes. The influence of WIPs on thermosteric sea level trends in the North Atlantic is up to the order of 1 mm yr-1 in both winter and summer, in the open ocean and at the shelf break. Smaller contributions are observed over the shelf areas of the North Sea. This study underscores the crucial role of WIPs in modulating sea-level changes and highlights the importance of including these processes in future sea-level rise assessments and climate projections. [ABSTRACT FROM AUTHOR]

The paper proposes a wave spectral partitioning method for the surface waves investigation and monitoring (SWIM) spectrometer based on the wave age and parameter optimization (WA-PO) method. The wave age criterion is a way to identify waves as wind waves or swells, and parameter optimization methods enable the modeling of wave spectra. The combination of the two can use the spectrum models to fit the SWIM spectra based on clarifying whether the spectrum models belong to wind waves or swells, which achieves spectral partitioning. The WA-PO method consists of four steps: peaks region dividing, spectral peaks searching, objective function constructing, and model parameters optimizing. The results show that compared with the partition products provided by the SWIM, the partition parameters obtained from the WA-PO method are closer to those of the Integrated Ocean Waves for Geophysical and other Applications (IOWAGA) numerical hindcast dataset developed from the WAVEWATCH III (WW3). The WA-PO method can prevent over-partitioning of the wave spectra and detect wind-wave components hidden in the swell partition. [ABSTRACT FROM AUTHOR]

The tsunami that was triggered by the 2024 Noto Peninsula Earthquake caused severe inundation along the coast on the northeastern tip of the peninsula, propagated over the sea with rough wind waves, and reached the coast and rivers located away from the peninsula. This manuscript presents the results of a field survey and a supplementary analysis for investigating the tsunami characteristics away from the peninsula where rough wind waves had a significant influence on the tsunami behavior. Video images captured by closed-circuit television (CCTV) cameras were used for onsite detection of the tsunami traces and for extracting time-varying water level profiles. Wind waves had little influence on the tsunamis along the lower reaches of the rivers, and the measured tsunami heights were consistent with each other in the nearby field. At most of the survey sites, the highest tsunami traces were created not by the first but by the following tsunami. Along Toyama Bay, the tsunami water levels first decreased within several minutes after the earthquake, and the arrival times for this negative tsunami peak was earlier in the southern part of the bay. These characteristics may indicate the existence of multiple tsunami sources inside Toyama Bay. [ABSTRACT FROM AUTHOR]

Near-surface ocean wind measurements are important for weather forecasting, determining surface transports, and estimating air-sea interactions; however, in-situ wind observations are often limited. Previous studies indicate that the equilibrium range of the surface gravity wave spectrum can be used to estimate surface wind velocity. This approach is tested using spectral wave measurements from the Coastal Data Information Program (CDIP) buoy array off Monterey, California. Quality controlled wind vectors inferred from wave spectra are statistically compared to measurements from a nearby National Data Buoy Center (NDBC) buoy, demonstrating strong agreement with the control observations with root mean square errors for speed and direction of 1.8 m/s for all wind speeds and 13.2° for wind speeds greater than 7 m/s. We expand this estimation method to account for biofouling, which causes high-frequency damping of the wave spectrum, and the effects of form factor, which impact the platform's dynamic response to high-frequency waves. The method produces wind-proxy measurements solely from wave spectra and wave-based drag parametrizations, making it useful for operational integration. This work demonstrates the ability to make robust wind velocity estimates using wave data from multiple sources, increasing the coverage of wind information over the coastal and open ocean. [ABSTRACT FROM AUTHOR]

The synchronization and intensity of fluctuating wind speeds and wave surfaces in wind–wave joint propagation processes are affected by the coherence of the marine ambient factors of fluctuating wind and random waves. This coherence further affects the precise calculations of wind–wave joint actions on marine structures. Therefore, a wind–wave joint propagation numerical flume was established based on the numerical simulation of random waves and fluctuating wind fields. A series of numerical simulations of wind–wave joint propagations were carried out. Based on the numerical results, the influences and influence laws of factors such as wind speed position height, significant wave height and wave spectrum peak frequency on the wind–wave coherence values were studied. According to the influence characteristics of these factors, a function of wind–wave coherence values for random wind–wave joint propagation was calculated. The coherence function takes frequency as the variable, while parameters include significant wave height, wind speed position height and wave spectrum peak frequency. Through a series of numerical simulation results, data fitting was used to calculate the parameter coefficients of the coherence function. The established random wind–wave coherence function can be described using the wind–wave joint fields of marine structures and the computational analyses of structural wind–wave joint actions. [ABSTRACT FROM AUTHOR]

A study of wave processes near Cape Svobodny on the south-eastern coast of the island Sakhalin using autonomous wave recorders and a weather station has been performed. Analysis of five-month data of sea level and temperature, atmospheric pressure and wind speed revealed that there are no significant peaks for wind and infragravity (IG) waves in the wave period range 2–600 s, and the wave energy is lower at the point protected by Cape Svobodny. During storms, there is an increase in the energy of IG waves. Waves detected at periods of 14.2 seconds, 3.62 minutes, and 8.85 minutes are related to swell and edge waves propagating seaward. For explanation of short waves, the Longuet-Higgins and Stewart theory was used which describes the dispersion of swell in the surf zone and the formation of free waves. Edge waves were analyzed using the Lamb model and the Bessel function of the first kind of zero order. Modelling of wave processes propagating shoreward revealed the presence of IG waves with periods of 20–110 seconds and edge waves with periods of 4.27–7.63 minutes, confirmed by the dispersion relation for Stokes waves on a sloping bottom. Sea water temperature fluctuations of more than 7 °C with periods of 3–100 minutes affect the propagation of waves with periods longer than 3 minutes, destroying the edge and leaky waves. Analysis of wind wave characteristics showed no significant wave processes, including wind waves, in the 2–20 second period range. The maximum wave height was observed during prolonged southern winds associated with a cyclone. This study is important for understanding wave processes in this area, aiding in predicting their behaviour and impact on the coastline.

Knowledge of the directional distribution of a wave field is crucial for a better understanding of complex air–sea interactions. However, the dynamic and unpredictable nature of ocean waves, combined with the limitations of existing measurement technologies and analysis techniques, makes it difficult to obtain precise directional information, leading to a poor understanding of this important quantity. This study investigates the potential use of a wavelet-based method applied to GPS buoy observations as an alternative approach to the conventional methods for estimating the directional distribution of ocean waves. The results indicate that the wavelet-based estimations are consistently good when compared to the framework of widely used parameterizations for the directional distribution. The wavelet-based method presents advantages in comparison with the conventional methods, including being purely data-driven and not requiring any assumptions about the shape of the distribution. In addition, it was found that the wave directional distribution is narrower at the spectral peak and broadens asymmetrically at higher and lower scales, particularly sharply for frequencies below the peak. The directional spreading appears to be independent of the wave age across the entire range of frequencies, implying that the angular width of the directional spectrum is primarily controlled by nonlinear wave–wave interactions rather than by wind forcing. These results support the use of the wavelet-based method as a practical alternative for the estimation of the wave directional distribution. In addition, this study highlights the need for continued innovation in the field of ocean wave measuring technologies and analysis techniques to improve our understanding of air–sea interactions. Significance Statement: This study presents a wavelet-based technique for obtaining the directional distribution of ocean waves applied to GPS buoy. This method serves as an alternative to conventional methods and is relatively easy to implement, making it a practical option for researchers and engineers. The study was conducted in a highly energetic environment characterized by high wind speeds and large waves, providing a valuable dataset for understanding the dynamics of marine environment in extreme conditions. This research has implications for improving our understanding of directional characteristics of ocean waves, which is crucial for navigation, offshore engineering, weather forecasting, and coastal hazard mitigation. This study also highlights the challenges associated with understanding wave directionality and emphasizes a need for further observations. [ABSTRACT FROM AUTHOR]

Fatigue load modeling is crucial for optimizing and assessing the lifespan of floating wind turbines. This study addresses the complex characteristics of fatigue loads on floating wind turbines under the combined effects of wind and waves. We propose a fatigue load modeling approach based on Vine copula theory and machine learning. Firstly, we establish an optimal joint probability distribution model using Vine copula theory for the four-dimensional random variables (wind speed, wave height, wave period, and wind direction), with model fit assessed using the Akaike Information Criterion (AIC), Bayesian Information Criterion (BIC), and Root Mean Square Error (RMSE). Secondly, representative wind and wave load conditions are determined using Monte Carlo sampling based on the established joint probability distribution model. Thirdly, fatigue load simulations are performed using the high-fidelity simulator OpenFAST to compute Damage Equivalent Load (DEL) values for critical components (blade root and tower base). Finally, utilizing measured wind and wave data from the Lianyungang Ocean Observatory in the East China Sea, simulation tests are conducted. We apply five commonly used machine learning models (Kriging, MLP, SVR, BNN, and RF) to develop DEL models for blade root and tower base. The results indicate that the RF model exhibits the smallest prediction error, not exceeding 3.9%, and demonstrates high accuracy, particularly in predicting flapwise fatigue loads at the blade root, achieving prediction accuracies of up to 99.97%. These findings underscore the effectiveness of our approach in accurately predicting fatigue loads under real-world conditions, which is essential for enhancing the reliability and efficiency of floating wind turbines. [ABSTRACT FROM AUTHOR]

Hydrodynamic processes are a major driver for marine systems, linking marine organisms with their environment. However, a lack of hydrodynamic data at an ecologically relevant spatial resolution has stymied our understanding of reef function, as exemplified by Lizard Island on the Great Barrier Reef. To address this gap, 23 to 27 Marotte HS current meters were deployed over three periods, collecting 15 months of current velocity data. Combining these data with wind and tide datasets, we provide a preliminary description of the circulation in the Lizard Island lagoon, examining wind and tide influence, and flushing time. During south-easterly trade winds, flood tides flow through the Lagoon Entrance, while wind-induced waves cross the Bird-South crest, driving a north-westerly flow through Loomis Channel and across the western lagoon. Ebb tides flow east–south-east through the Lagoon Entrance and south-west through the Palfrey-South channel. Tides contribute a mean of 20.4% to the overall current speed, particularly in deeper sites with less reef interference, while shallow sites were more influenced by wind. Lizard Island lagoon flushing times ranged from a few hours to 10 days; longer during periods with low wind speeds. Hindcast flushing times during the 2016 coral bleaching event (following 8 Degree Heating Weeks) were approximately 22 h, suggesting that flushing time likely had minimal influence on bleaching. Our analyses provide initial insights into the circulation of the Lizard Island system and aid understanding of the potential relationships between reef organisms and their physical environment, bridging the gap between ecology and hydrodynamics. [ABSTRACT FROM AUTHOR]

Experimental parameters of wind-driven waves obtained with a measuring pole near the coastal line of Lake Baikal using video recorders placed on a slightly submerged mast are analyzed in the present work. The measurements were carried out during the fall period. The short-period dynamics of the characteristics of surface wind-driven waves arising on the shallow water surface is analyzed. Dependences are established of the wave heights on the wind speed and direction in an open region of Lake Baikal in the daytime; their maxima are recorded in the second half of the day at the western wind direction. The temporal variations of the wave periods and heights are shown, and the nonlinear gravitational wave modes are detected on the shallow water surface. As a result of these processes, the short-period wave heights reach their maximum values. Radar measurements of the wind-driven wave characteristics have shown a dependence of the back-reflected signal intensities on the variations in the wind-driven wave heights. Small-scale inhomogeneities observed on the water surface in the form of ripples, responsible for backscattering of wind-driven wave crests, are well recognized with a nanosecond radar. [ABSTRACT FROM AUTHOR]

Wind gusts play an important role in the modulation of wind stress and have remarkable influence on surface waves. The response of wind stress and surface wave to wind gusts is investigated under wind-wave and swell dominated conditions through direct flux measurements on two coastal towers in the Bohai Sea and South China Sea. Observations show that wind stress significantly increases under gusty conditions compared to non-gusty conditions whether dominated by wind-waves or swells. The stronger the gusts, the greater the increase in wind stress. However, surface waves show different responses to the gusts under wind-wave and swell dominated conditions. When wind-waves dominate, the stronger the gust, the higher the significant wave height, while when swells dominate, the relatively lower the significant wave height. The separation of wind-wave and swell spectra indicates gusts can increase the wind-wave energy and decrease the swell energy. The weakening of swell and the strengthening of wind-wave may lead to an increase in wind stress. [ABSTRACT FROM AUTHOR]

The study analyzes the impact of various wave-induced processes on relative dispersion and diffusivities in the North Sea using OpenDrift, a Lagrangian particle-drift model driven by a fully coupled NEMO-WAM model. The coupled model parameterizations include sea state-dependent momentum flux, energy flux, and wave-induced mixing. The study demonstrates that Eulerian currents, influenced by the interaction between the ocean and wave models, significantly enhance particle transport. Experiments conducted using drifter clusters obtained during an RV Heincke excursion further confirm the impact of wind-wave coupling. The analysis includes a comparison of results from experiments with and without wave coupling. The impact of diffusion in the Lagrangian model on relative dispersion is investigated, with the conclusion that diffusion is essential for achieving precise simulations. Furthermore, the incorporation of wind-wave-driven mixing parameters, including sea state-dependent momentum flux, energy flux, and wave-induced mixing, into the hydrodynamic model leads to elevated levels of relative dispersion and diffusivity. [ABSTRACT FROM AUTHOR]

High‐precision observation of significant wave height (SWH) is crucial for marine research. The Surface Waves Investigation and Monitoring (SWIM) aboard the China France Oceanography Satellite (CFOSAT) provides the ocean wave spectrum that allows for the calculation of the off‐nadir SWH parameters, but there exists a certain bias with the in‐situ SWH values. To improve the accuracy of the SWH calculation bias from the off‐nadir 6°, 8°, 10° wave spectra and the whole combined spectrum, this paper establishes a spatio‐temporal hybrid model that combines convolutional neural network (CNN) and long short‐term memory network (LSTM). Additionally, to further correct bias exhibited under high sea state, we introduce a bias correction module based on deep neural network (DNN) to adjust the SWIM off‐nadir SWH greater than 4 m. The experimental results demonstrate a significant enhancement in the accuracy of corrected SWIM off‐nadir SWH, and the best calibration result is 10° with 0.267 m root mean square error (RMSE), and 0.979 correlation coefficient (R) compared with the ERA5 value. We conducted a comprehensive study and analysis on the performance of the proposed model under different wave heights, extreme sea states, and wind and swell regions. Meanwhile, the buoy and altimeters are leveraged to render further evaluation the RMSE of the corrected SWH is less than 0.5 m. Plain Language Summary: The Surface Waves Investigation and Monitoring (SWIM) on the China France Oceanography Satellite (CFOSAT) provides wave data support for ocean research. However, the significant wave height (SWH) parameter calculated from the SWIM off‐nadir spectra has a certain bias from the real value due to the influence of speckle noise. In order to improve the accuracy of the SWIM off‐nadir SWH parameter, we developed a CNN‐LSTM model and introduced a high sea state bias correction network to improve the accuracy of SWH and achieve the purpose of correction. The analysis evaluated the correction performance across various sea conditions, comparing the corrected SWH data with measurements from altimeters and buoys. The findings demonstrated that the root mean square error of the corrected SWH was consistently below 0.5 m, with a correlation coefficient exceeding 0.940. This underscores the effectiveness of our model in enhancing the precision of nadir SWH data bias from SWIM instruments. Key Points: A model of convolutional and long short‐term memory neural network is developed to calibrate the surface waves investigation and monitoring (SWIM) off‐nadir significant wave heightThe corrected SWIM off‐nadir significant wave height achieves comparable accuracy with the Jason‐3, HY‐2B, and buoysThe proposed model performs well in the calibration of the wind wave region and the swell region [ABSTRACT FROM AUTHOR]

The increasing integration of intermittent renewable sources (RSs) poses a dynamic frequency stability challenge for modern marine vessel microgrids. To address this issue, this paper proposes a novel control approach, specifically targeting frequency and tie-line power stabilization in a diverse source marine microgrid (MμG) with two intertied areas featuring renewable (wind-wave) sources. The suggested approach introduces a modified tilt-integral active disturbance rejection (TI-ADRC) controller designed to ensure effective damping of power frequency oscillations. As the control scheme depends on the optimal setting of the proposed controller, a recently developed marine predator technique (MPT) has been adopted. The performance of the proposed controller is compared with other recent controllers viz. PID, tilt-integral derivative (TID), two-degree-of-freedom (2DOF)-PID, fuzzy-PI, and ADRC to validate its superiority. To further enhance the system dynamics, a precise modeling of inertia emulated direct current (IEPDC) tie link is incorporated in microgrid system. The impact assessments, considering time delays with pre/post IEPDC link, demonstrate a substantial 57.79% and 81.53% reduction in peak frequency overshoot compared to DC link (conventional model) and AC link, respectively. The analysis of the eigen plot confirms the stability of the control system. Sensitivity assessments of the controller against ± 30% parametric variations and load fluctuations are conducted, affirming its robustness. Finally, the result from OPAL-RT confirm the practicality of the proposed method. It is asserted that the suggested controller is reliable and functions well in n the presence of diverse disruptions and parametric variations. • An integrated two-area inter-tied marine microgrid model based on intermittent renewable sources for secondary frequency control. • Novel MPT-tuned tilt integral-active disturbance rejection controller (TI-ADRC) for marine microgrid. • Comprehensive modelling of inertia emulated DC (IEPDC) link with parallel AC link. • Stability and dynamic response analysis of the proposed control strategy. • Sensitivity analysis to validate robustness of the proposed control strategy under uncertain parametric variation. [ABSTRACT FROM AUTHOR]

This study analyzed the past wave climate of the Black Sea region for the period from 1988 to 2021. The wave field has been simulated using the state-of-the-art, third-generation wave model WAVEWATCH III forced by the ECMWF reanalysis ERA5 winds, with the model resolution being the highest ever applied to the region in a basin-scale climate study. The surface currents provided by the Copernicus Marine Service have been included in the wave model to evaluate wave--current interactions. The wave model results have been validated with respect to satellite and buoy observations, showing that the simulation accurately reproduces the past evolution of the wave field, exceeding 0.9 correlation with respect to satellite data. The inclusion of wave--current interaction has been positively evaluated. Four statistics (significant wave height 5th and 95th percentiles, mean, and maxima) have been used to describe the wave field at seasonal timescale, showing a clear distinction between the Western (rougher sea conditions) and Eastern (calmer sea conditions) sub-basins. Furthermore, the intra-annual wave climate variability has been investigated using a Principal Component Analysis (PCA) and the Mann--Kendall test on significant wave height (SWH). This study represents the first time the PCA is applied to the region, identifying two main modes that highlight distinct features and seasonal trends in the Western and Eastern subbasins. Throughout most seasons, the SWH trend is positive for the Eastern basin and negative for the Western basin. The PCA shows a regime shift with increasing eastward waves and decreasing north and north-eastward waves. Finally, SWH correlation (r) with four Teleconnection indexes (East Atlantic Pattern, Scandinavian Pattern, North Atlantic Oscillation, and East Atlantic/West Russia Pattern) revealed that the strongest r is observed with the Eastern--Atlantic--Western Russia teleconnection, with a peculiar spatial pattern of correlation, and is positive for the northwestern and negative for the southeastern sub-basin. [ABSTRACT FROM AUTHOR]

Numerical modeling of waves in sea ice covered regions of the oceans is important for many applications, from short-term forecasting and ship route planning up to climate modeling. In spite of a substantial progress in wave-in-ice research that took place in recent years, spectral wave models - the main tool for wave modeling at regional and larger scales - still don't capture the underlying physics and have rather poor predictive skills. This article discusses recent developments in wave observations and spectral wave modeling in sea ice, identifies problems and shortcomings of the approaches used so far, and sketches future directions that, in the opinion of the author, have the potential to improve the performance of wave-in-ice models. [ABSTRACT FROM AUTHOR]

Sea surface wind, waves, and currents are the three basic parameters that describe the dynamic process of sea surface, and they are coupled with each other. To more accurately describe large-scale ocean motion and extract the ocean dynamic parameters, we adopt the spaceborne Doppler measurement to estimate the radial Doppler velocity generated by the sea surface motion. Due to the presence of wind and waves, the Doppler spectrum will be formed, shifted and broadened. Pulse-pair phase interference is used to obtain the Doppler spectrum from the sea surface echo. We simulate the Doppler spectrum with different look geometry and ocean states in a spaceborne condition. In this paper, the Doppler centroid variations are estimated after reducing the platform Doppler velocity under different observation conditions. With the increase in wind speed, the measured Doppler shift increases, and the simulated Doppler centroid accuracy is estimated. In addition, the measurement error along the trace direction is at the maximum, and the error in the cross-track is the smallest. At moderate wind-wave conditions, the Doppler velocity offset can be less than 0.1 m/s. [ABSTRACT FROM AUTHOR]

The presence of the drift current complicates analysis of the dispersion relation for wind waves. In the general case, this relation is derived from analysis of the Rayleigh equation which has no analytical solution for an arbitrary velocity profile. In the limiting case, when the length of the gravity–capillary wave is significantly less than the typical flow depth, the simple Doppler approximation can be used. However, this approximation is not valid in the general case and it is necessary to take into account the vertical profile of the horizontal velocity up to the depth that corresponds to the considered wavelengths. The drift velocity profile is determined using Particle Image Velocimetry. The high-resolution spatiotemporal spectra of waves are obtained using the color schlieren technique. A small addition of sodium dodecyl sulfate allows one to estimate the effect of soluble impurities on the structure of the drift current and to modify the ratio between the drift current depth and length of the gravity–capillary wave. In the present work, an algorithm for numerical calculation of the dispersion relation for a given velocity profile is used. It is shown that the Rayleigh equation adequately describes the dispersion relation in a wind channel under conditions where the influence of the profile is strong and cannot be reduced to simple Doppler corrections. Thus, deviations of dispersion relations obtained in geophysics from simple approximations can correspond to different relationships between wavelengths and drift current depth. [ABSTRACT FROM AUTHOR]

Processed and analyzed sea surface wave characteristics derived from an up-looking acoustic Doppler current profiler (ADCP) for the period 2016–2022 are presented as a dataset available from the public open-access repository of SEA scieNtific Open data Edition (SEANOE) at 10.17882/96904. The collected data include full two-dimensional wave fields, along with computed bulk parameters, such as wave heights, periods, and directions of propagation. The ADCP was mounted on the submerged Deep Levantine (DeepLev) mooring station located 50 km off the Israeli coast to the west of Haifa (bottom depth ∼1470 m). It meets the need for accurate and reliable in situ measurements in the eastern Mediterranean Sea as the area significantly lacks wave data compared to other Mediterranean sub-basins. The developed long-term time series of wave parameters contribute to the monitoring and analysis of the region's wave climate and the quality of wind–wave forecasting models. [ABSTRACT FROM AUTHOR]

The densely populated coast of the Gulf of Guinea (GoG) is experiencing escalating erosion from climate change (CC). To assess Longshore Sediment Transport (LST) changes in the past and future, an empirical formula was used to model the GoG's LST. Nearshore wave conditions, crucial for LST estimation, were derived by projecting significant wave height, mean wave period, and mean wave direction from deep water to the breaker zone. These wave conditions were used as input for LST computation. Analysing three time slices: Past (1979–2005), mid-century (2026–2045), and end-century (2081–2100) under RCPs 4.5 and 8.5, results indicate continuous increase in LST in most locations, with local and seasonal variations. LST magnitudes range from 104 to 105 m3y−1 in the GoG, with the Cameroonian coast having the least. This aligns with the rising wave energy from CC. LST directions are predominantly eastward, though some locations, like off Lagos and Cameroon-Gabon coasts, show westward trend, correlating with coastal orientation influenced by southward wave directions. RCP 8.5 projections suggest mid-century increase, intensifying by end of century, with yearly rates of change around 103 m3y−1 and future LST changes up to 105 m3y−1. This situation implies accelerated sediment removal, heightening erosion. [ABSTRACT FROM AUTHOR]

Hydraulic experiments using a wave flume with a wind tunnel at a scale of 1/40 were carried out to investigate the effect of wind on wave overtopping of a vertical seawall. To ascertain the possible effects of wave breaking, incident waves with various wave steepness (0.0102 to 0.0371) and three kinds of wind forcing (0 m/s, 6.84 m/s, 10.04 m/s) were used. The authors found that winds significantly increased the overtopping rate in general, and that there is a clear relationship between the overtopping rate and the wave steepness. Velocity fields obtained from PIV analysis revealed that the onshore winds directly enhanced the transport of overtopping water mass. The influence of the wind on the wave hydrodynamic processes that indirectly have an effect on the overtopping rate (such as the formation of a partially standing wave, breaker location, and breaker type) is also discussed. The perspective of treating wave overtopping as a transport of water mass could provide a novel understanding of complex fluid behavior, which would help to formulate countermeasures against future disasters influenced by intensive wind forcing. [ABSTRACT FROM AUTHOR]

This paper discusses the extension of an optical liquid film thickness measurement technique to characterize liquid film flow rate in wavy thin liquid film flow. The technique, based on laser refractometry, is used to measure wave height, shape, frequency, and velocity. A two-zone model to process the measured wave characteristics is used to estimate the liquid film flow rate. The method is validated in a falling film facility where easy optical access allows comparisons of the wave velocity measurements with high-speed videos and where the calculated liquid film mass flow rate can be compared with actual measurements. The paper provides a framework for analyzing time-resolved film thickness data using multizone models in more complex liquid film flows, such as in two-phase annular flow. [ABSTRACT FROM AUTHOR]

Natural sea waves are typically multi-directional. However, the existing studies on the interaction of waves and structures mostly concentrate on uni-directional waves. In this study, using a higher-order boundary element method based on the nonlinear potential flow theory and the perturbation expansion technique, a numerical model is developed to investigate the hydrodynamic performance of a semi-submersible wind turbine foundation in uni- and multi-directional waves. Comprehensive validations with the wave-tank experiment are conducted. It is found that the significant platform response increases with the peak wave period in uni-directional irregular waves, while the high-frequency "energy" ratio changes little. The significant wave height hardly influences motion responses from either the time- or the frequency-domain perspective. In multi-directional irregular waves, the translational motions exhibit monotonicity with wave directionality. The energy concentration around the primary direction leads to a dominant wave-frequency motion and an increase in the high-frequency "energy" ratio. Although the individual modal motion responses are variable functions of wave nonlinearity, their averaged translational and rotational motions are nearly constant, indicating an energy transition or a trade-off relationship among the modal motions. In addition, unlike the uni-directional wave case, the low- and high-frequency "energy" ratios increase quadratically and decrease linearly with the significant wave height in multi-directional waves, respectively. All these findings demonstrate that wave directionality can change the wave–structure interaction properties and therefore needs to be adequately considered in engineering applications. [ABSTRACT FROM AUTHOR]

Wind generated waves of a sea state are generally the result of the superposition of wind sea and swells, making the frequency-direction wave energy distribution crucial for comprehending this behavior. Wave spectral partitioning methods provide groups of waves with similar characteristics, thus they have been usually applied to identify wind sea and swell. In addition, several swells can coexist in a sea state. This study develops a method to estimate the wave systems and analyze their characteristics over the coast worldwide using 32year (1989-2020) historical information and more than 10.000 locations. A wave system is considered as the long-term climate conditions prevailing over a frequencydirection wave energy area collecting similar environmental and physical characteristics. The method is applied for the hourly time series of the directional wave spectra. First, the watershed clustering algorithm is used and the partitions found are classified as wind sea or swells based on a wave age criterion. The information obtained from the swell spectral partitions is then used to estimate the probability of their occurrence within specific frequencydirection bins and the clustering algorithm is applied anew to this population in order to identify the number of significant long-term climate wave systems locally and their characteristics. Outcomes reveal that on average swells coexist with wind sea in approximately 70% of the global coast, whereas about 25% is predominantly dominated by pure swells and the wind sea dominates only in the 5%. Only the 2% of the global coast line presents one swell wave system. About 50% of the global coastal locations exhibit three and four, whereas the 15% presents two swell wave systems. The analysis shows that about 30% of the coastal locations present at least five swell wave systems, mostly on Pacific islands and enclosed seas. [ABSTRACT FROM AUTHOR]

Working toward replacing conventional fossil fuels with alternative renewable energy, offshore renewable energy technologies give promising solutions, even though each of the types (wind, wave, tidal and thermal) is at a different stage of development and with its own unique challenges and opportunities. This paper is focused on sea wind wave energy harvesting through a hybrid system that combines both a water turbine with oscillating blades and "Wells"-type air turbine. A test bench was designed and tested at different flow rates to study the performance of the hybrid system and more precisely the "Wells"-type turbine. Experimental studies of the main parameters of a turbine were conducted, which demonstrated the efficiency of the turbine and its good practical application. The experimental results show good agreement with the preliminary performed numerical simulations, as well as with the published data. [ABSTRACT FROM AUTHOR]

The integration of wave energy converters (WECs) into floating offshore wind turbine (FOWT) can effectively reduce costs and increase power generation. When WECs are integrated into FOWT, the hydrodynamic interference, motion coupling, and other factors contribute to the high spatial dimension of the coupled optimization, making it difficult to find the globally optimal solution. Therefore, this study proposes an optimization method based on a wind‐wave coupling model, and takes a new wind‐wave hybrid system as an example for verification and analysis. First, the experimental design is completed through random sampling, and the corresponding WECs and wind turbine power of each sample point are calculated using full coupling simulation. And then according to the design input and simulation results, the wind‐wave coupling model is obtained by training the elliptical basis functions neural network (EBFNN). At last, based on this model, the non‐dominated sorting genetic algorithm II (NSGA‐II) is used to optimize the WECs microarray. The results show that the prediction model established in this paper has high accuracy and is used with the NSGA‐II to effectively improve the wind‐wave coupling energy harvesting. This method can effectively solve the problem of high coupling dimensions in the process of hybrid system design. [ABSTRACT FROM AUTHOR]

This article examines the poetry of Derek Mahon and its exploration of water, land, and earth. It highlights how Mahon's early works focused on fire and air, but later shifted to a focus on water and earth, particularly in coastal landscapes. The article also discusses the lack of attention given to Mahon's ecocritical aspects compared to his contemporaries, and argues for a broader perspective in understanding his work. Additionally, the text explores Mahon's treatment of land and sea in relation to his cultural identity and desire for change, as well as his later shift towards a more inclusive and tolerant view of the environment. Overall, Mahon's poetry emphasizes the interconnectedness of life on earth and the importance of a dynamic perspective. [Extracted from the article]

Coastal erosion caused by continuous sea wave action is destructive. One potential solution to reduce the impact of waves and coastal erosion is the utilization of mangrove forests as natural barriers. The Banyuglugur Coastal Area has a thriving mangrove forest that grows along 5.1 km of coastline. The objective of this research is to determine the percentage reduction of the mangrove forest as an energy buffer and the wave height along the Banyuglugur Coast. The method employed to achieve this goal involves numerical simulation using Delft3D, considering the influence of mangrove forest length, tides, wind, and wavelength. The Delft3D-Coupling model is used, combining two modules, FLOW for tidal simulation and WAVE for wind-wave simulation. Mangroves with a width of 70 m in Zone A are high-density mangrove locations that can reduce wave energy by 62.14%, while low-density mangroves in Zone D with a width of 30 m can reduce wave energy by 44.28%. The simulation results indicate that mangrove forests on Banyuglugur Beach, with an average width of 50 m, can dampen waves by an average of 52.8% and reduce the average wave height by 39% compared to incoming waves. [ABSTRACT FROM AUTHOR]

X-band marine radar captures the signal reflected from the sea surface. Theoretical studies indicate that the initial unfiltered signal contains meaningful information about wind wave parameters. Traditional methods of significant wave height (SWH) estimation rely on physical laws describing signal reflection from rough surfaces. However, recent studies suggest the feasibility of employing artificial neural networks (ANNs) for SWH approximation. Both classical and ANN based approaches necessitate costly in situ data. In this study, as a viable alternative, we propose generating synthetic radar images with specified wave parameters using Fourier-based approach and Pierson–Moskowitz wave spectrum. We generate synthetic images and use them for unsupervised learning approach to train a convolutional component of the reconstruction ANN. After that, we train the regression ANN based on the previous convolutional part to obtain SWH back from the synthetic images. Then, we apply preliminary trained weights for the regression model to train SWH approximation on the dataset of real sea clutter images. In this study, we demonstrate the increase in SWH estimation accuracy from radar images with preliminary training on synthetic data.

This paper provides information on the integrated geological and geophysical investigations of the fracture zones of the Tropical Atlantic (cruise 65 of the RV Akademik Ioffe), as well as on the geomagnetic survey, passing observations of wind-generated waves, and quantitative distribution of cetaceans and flying fish in the North Atlantic (cruises 64 and 65 of the RV Akademik Ioffe) in October–December 2023. The preliminary scientific results are discussed. [ABSTRACT FROM AUTHOR]