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The nearshore wind stress, u∗2 ${u}_{\ast }^{2}$, is examined using machine‐learning models for air‐ocean data collected via new flux buoys deployed across four experiments. Consistent with prior nearshore studies, existing open‐ocean models predict nearshore u∗2 ${u}_{\ast }^{2}$ with a large error of 0.0152 m2/s2. Gaussian Process Regression (GPR) for nearshore u∗BM2 ${u}_{\ast \text{BM}}^{2}$ is developed, reducing errors to 0.0108 m2/s2. Nearshore air‐sea parameterizations are examined with wind speed (61%) and the wind‐wave frequency of encounters (16%) being the most important. A simpler nearshore, GPR‐derived, wind‐dependent‐only model (u∗NSU2 ${u}_{\ast \text{NSU}}^{2}$) is developed, with errors of 0.0135 m2/s2. GPRs, evaluated using identical variables, were applied to nearshore observations, and these observations modeled with open‐ocean formulations for an initial comparison of parameterizations between these two regimes. The parameterizations are similar, though with subtle nonlinear differences. The new nearshore data set and machine‐learning models enhance the accuracy of predictions and understanding of differences from the open‐ocean. Plain Language Summary: Understanding and accurately parameterizing wind stress on the ocean surface is crucial for modeling oceanic and atmospheric phenomena. Despite its significance, nearshore wind stress and its influencing factors remain inadequately understood due to limited in situ observations and the complexity of the problem. To address this gap, ten shallow‐water air‐sea buoys were developed and deployed alongside directional wave buoys in four field experiments, yielding a substantial data set of nearshore wind stress and associated variables. Discrepancies between nearshore and open‐ocean models were observed, with open‐ocean models exhibiting large errors. Machine‐learning models enhance the accuracy of predictions and understanding of the input variables. A new data‐informed machine‐learning model for nearshore wind stress significantly reduced the error by 30%. Each variable parameterization is described, and a simple model for wind stress based solely on wind speed is provided. Furthermore, an examination of wind stress parameterizations revealed similarities and differences between nearshore and open‐ocean, primarily attributed to wind speeds. These findings significantly enhance the accuracy of weather and ocean forecasts, particularly for nearshore regions. Key Points: Ten air‐sea buoys for winds and fluxes, deployed with wave buoys in four experiments, improve nearshore wind stress observation gapsSupervised machine learning enhances nearshore wind stress predictions, yielding parameterized variable responses without preconceptionsNearshore wind stress parameterizations relative to the open‐ocean have similar variable responses though with small nonlinear differences [ABSTRACT FROM AUTHOR]

Copyright of Journal of Shanghai Jiaotong University (Science) is the property of Springer Nature and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

To meet the cross-domain surfaced communication requirements of underwater information in cross-domain cooperative operations, a low-power cross-domain communication buoy system was designed by taking advantage of the buoy’s flexible deployment, long-term concealment, and flexible payload characteristics. This system mainly supported deep-sea deployment at great depths and long-term silent watch and concealed cross-domain communication upon activation. Additionally, it could autonomously destruct critical components according to preset instructions, thus avoiding the exposure risk of surfaced communication on underwater platforms such as submarines, and it is relatively easy to deploy and sustain. Test results indicate that the designed system features high pressure resistance, low power consumption, and certain scalability, offering good prospects for application.

High frequency(HF) sky-wave propagation is limited by the working frequency, and the antenna size meeting high gain and adapting to high sea conditions is large, so the application scenario is seriously limited. For the demand of cross-domain long-distance transmission of far-sea science detection information, a cross-domain buoy communication technology integrating HF communication, underwater acoustic communication and unmanned buoy characteristic was proposed. The composition and working principle of far-sea cross-domain transmission buoy devices were introduced, and the working flow was designed. Through the design of a flexible HF antenna with variable length and integrated power amplifier components for water cooling and heat dissipation, the advantages of high antenna gain, strong adaptation to sea conditions, and cross-medium transmission were ensured. The simulation analysis shows that the proposed communication method can effectively guarantee the communication effect and achieve reliable cross-domain long-distance communication of HF signals in high sea conditions and complex interference environments, providing certain technical support for the development of maritime long-distance cross-domain communication.

Abstract The nearshore wind stress, u∗2, is examined using machine‐learning models for air‐ocean data collected via new flux buoys deployed across four experiments. Consistent with prior nearshore studies, existing open‐ocean models predict nearshore u∗2 with a large error of 0.0152 m2/s2. Gaussian Process Regression (GPR) for nearshore u∗BM2 is developed, reducing errors to 0.0108 m2/s2. Nearshore air‐sea parameterizations are examined with wind speed (61%) and the wind‐wave frequency of encounters (16%) being the most important. A simpler nearshore, GPR‐derived, wind‐dependent‐only model (u∗NSU2) is developed, with errors of 0.0135 m2/s2. GPRs, evaluated using identical variables, were applied to nearshore observations, and these observations modeled with open‐ocean formulations for an initial comparison of parameterizations between these two regimes. The parameterizations are similar, though with subtle nonlinear differences. The new nearshore data set and machine‐learning models enhance the accuracy of predictions and understanding of differences from the open‐ocean.

Abstract To address the issue of poor accuracy in typhoon wind data, this paper presents a methodology for the calibration of typhoon wind data while conducting an analysis and evaluation of the associated uncertainties. The approach commences with the introduction of two wind field data calculation models. The first model facilitates the correction of buoy attitude, thereby transforming inaccurate buoy wind speed data into real-speed data. In parallel, the second model enables the conversion of buoy-observed true velocity into neutral stable stratified wind parameters, leveraging satellite-derived data for precise calculations. Subsequently, the paper undertakes the task of spatio-temporal alignment between buoy data and satellite observations. Ultimately, a comprehensive comparative analysis is conducted by juxtaposing the ERA5 database with data collected from a moored buoy equipped with the R.M. YOUNG wind monitor. A new simulation method for satellite wind speed data inversion is proposed, and the experimental results demonstrate the effectiveness of the proposed calibration method in enhancing the accuracy of typhoon wind field data. In particular, the maximum wind speeds recorded were 20.15 m s−1 and 13.22 m s−1 during Typhoon "Jangmi (202005)" and "Maysak (202009)," respectively. Furthermore, the mean square errors (MSE) for our method were measured at 0.31 m s−1 and 0.28 m s−1, outperforming the satellite-derived indicators. The expanded uncertainty of measurement results for the two typhoons was calculated at 0.39 m s−1 and 0.34 m s−1, closely aligning with the MSE values. These computational models present a valuable means of enhancing the precision and reducing uncertainty in satellite-derived data. The findings presented in this paper hold great promise for applications in typhoon forecasting, investigations of air-sea interactions, and disaster prevention and mitigation efforts.

In base-station-based underwater wireless acoustic networks (B-UWANs), effective handover mechanisms are necessary to ensure seamless data services for mobile nodes such as autonomous underwater vehicles (AUVs). Unlike terrestrial base stations (BSs), moored buoy BSs in B-UWANs experience motion responses due to wave loads under environmental conditions, posing unique challenges to the handover process. This study examines how BS motion affects handover decision errors, which arise when AUVs incorrectly initiate handovers to unintended BSs due to BS motion. By utilizing the AUV–BS distance as a handover triggering parameter, our analysis reveals a significant increase in decision errors within the overlapping regions when both the current and target BSs are in motion, especially when moving in the same direction. In addition, these errors intensify with the magnitude of BS motion and are exacerbated by smaller BS network radii. Based on these simulation results, we present an analytical framework that not only measures the influence of BS motion on the AUV–BS distance but also provides strategic insights for refining underwater handover protocols, thereby enhancing operational reliability and service continuity in B-UWANs. [ABSTRACT FROM AUTHOR]

With the western North Pacific being one of the most active typhoon hotspots, a reliable buoy system is essential for in situ observations during typhoon passages. This study details the development and implementation of two improved buoys designed by National Taiwan University based on the Autonomous Temperature Line Acquisition System. It aims to establish a buoy network for near realtime, high-resolution meteorological and oceanic data collection during typhoon periods in the western North Pacific. The buoy system was distinguished by its reliable design, low power-consumption system, dual satellite and radio communication system, and inductive modem-based data acquisition system. Moreover, the system was proven robust to extreme weather conditions and fishing challenges. From 2015 to 2022, we conducted sea trials in typhoon hotspot regions every summer (normally June to October), demonstrating the buoys' durability and capability to withstand 21 typhoons while collecting valuable scientific data. [ABSTRACT FROM AUTHOR]

The suspended configuration of inter-array power cables between floating offshore wind turbines necessitates using various ancillary equipment, such as buoy elements and bend stiffeners, to maintain the desired cable geometry. The failure analysis is an important step in the design of an inter-array dynamic power cable layout. This study investigates the impact of buoy element failures on the structural integrity and fatigue life of inter-array power cable configurations in offshore environments, focusing on four environmental conditions representative of the North Sea. Utilizing numerical simulations and fatigue analysis in OrcaFlex, static and dynamic analyses are conducted to assess maximum tension, minimum bend radius (MBR), and fatigue life under single and two failure scenarios of buoy elements. The results indicate that single buoy failures significantly increase maximum tension at hang-off points. At the same time, MBR is found to be the smallest at the failure position, aiding in failure point identification. In addition, for the two buoy element failure scenarios, the maximum tension increase poses risks to structural integrity, while MBR and fatigue life have high sensitivity to the applied environmental conditions. [ABSTRACT FROM AUTHOR]

To address the issue of poor accuracy in typhoon wind data, this paper presents a methodology for the calibration of typhoon wind data while conducting an analysis and evaluation of the associated uncertainties. The approach commences with the introduction of two wind field data calculation models. The first model facilitates the correction of buoy attitude, thereby transforming inaccurate buoy wind speed data into real-speed data. In parallel, the second model enables the conversion of buoy-observed true velocity into neutral stable stratified wind parameters, leveraging satellite-derived data for precise calculations. Subsequently, the paper undertakes the task of spatio-temporal alignment between buoy data and satellite observations. Ultimately, a comprehensive comparative analysis is conducted by juxtaposing the ERA5 database with data collected from a moored buoy equipped with the R.M. YOUNG wind monitor. A new simulation method for satellite wind speed data inversion is proposed, and the experimental results demonstrate the effectiveness of the proposed calibration method in enhancing the accuracy of typhoon wind field data. In particular, the maximum wind speeds recorded were 20.15 m s−1 and 13.22 m s−1 during Typhoon "Jangmi (202005)" and "Maysak (202009)," respectively. Furthermore, the mean square errors (MSE) for our method were measured at 0.31 m s−1 and 0.28 m s−1, outperforming the satellite-derived indicators. The expanded uncertainty of measurement results for the two typhoons was calculated at 0.39 m s−1 and 0.34 m s−1, closely aligning with the MSE values. These computational models present a valuable means of enhancing the precision and reducing uncertainty in satellite-derived data. The findings presented in this paper hold great promise for applications in typhoon forecasting, investigations of air-sea interactions, and disaster prevention and mitigation efforts. [ABSTRACT FROM AUTHOR]

In this study, we addressed the problem of maximum output power in wave energy devices by analyzing the forces acting on the buoy and oscillators under the influence of ocean waves. The motion models for both floating devices and oscillators were developed, and algorithms were devised to determine the maximum output power of wave energy devices. When the buoy was only undergoing linear motion, a second-order ordinary differential equation could be established with displacement as the unknown variable. The main objective of this study was to maximize power, which was composed of the power generated by the damper, with the damping coefficient as the decision variable. Additionally, it was necessary to consider the following constraints in the motion equations: gravity, buoyancy, wave excitation force, added inertia force, wave damping force, static water restoring force, and the reactive forces from the damper and spring. By solving an unconstrained minimization problem related to the damping coefficient, the solution to achieve maximum power during linear motion could be found. When the rotation of the buoy was considered, we needed to modify the objective function to include the contribution of the rotational damper and introduce the rotational damping coefficient as a decision variable. Furthermore, we needed to add torque analysis as a constraint to account for the rotational motion of the buoy. Ultimately, the wave electric power generation system would provide the optimal power design solution that took into account both linear and rotational motions of the buoy. [ABSTRACT FROM AUTHOR]

The Great Lakes and connecting waters encompass a vast and diverse ecosystem that presents scale challenges for management similar to those of the coastal ocean. Technological approaches to overcome the scale challenges have primarily been adapted from oceanographic applications and technologies, and from upscaling inland lake methods designed for shallower and calmer water bodies. Many standard methods for studying Great Lakes habitat and biota have long lag times between field collection and data availability. Many also miss much of the dynamics, three-dimensional complexity, and spatial variability needed to manage the system effectively. Even baseline conditions are not well characterized for many parts of the Great Lakes ecosystem (e.g. bathymetry and critical habitat, life cycles and food webs, night and winter movement and activity of organisms). Emerging technologies are beginning to address these needs but require coordination, consistent investment, training, and governance linkages. Here we survey recent technological advances and show how they are contributing to improved adaptive management of the Great Lakes ecosystem by reducing uncertainty and increasing understanding of physical, biological, and chemical processes, and the human dimensions of resource management and restoration. [ABSTRACT FROM AUTHOR]

With the inception of the Argo program, the global ocean observation network is undergoing continuous advancement, with profiling buoys emerging as pivotal components of this network, thus garnering increased attention in research. In efforts to enhance the efficiency of profiling buoys and curtail energy consumption, a teardrop-shaped buoy design is proposed in this study. Moreover, an optimization methodology leveraging neural networks and genetic algorithms has been devised to attain an optimal profile curve. This curve seeks to minimize drag and drag coefficient while maximizing drainage, thereby improving hydrodynamic performance. Simulation-based validation and analysis are conducted to assess the efficacy of the optimized buoy design. Results indicate that the drag of the teardrop-shaped buoy with a deflector decreased by 9.2% compared to pre-optimized configurations and by 22% compared to buoys lacking deflectors. The hydrodynamic profile devised in this study effectively enhances buoy performance, laying a solid foundation for ocean thermal energy generation and buoyancy regulation control. Additionally, the optimized scheme serves as a valuable blueprint for the design of ocean exploration devices. [ABSTRACT FROM AUTHOR]

Copyright of Ordnance Industry Automation is the property of Editorial Board for Ordnance Industry Automation and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

This exercise aims to discover the Impact of Physical Education, Learning Sports, and Health on Body Mass Index and Physical Fitness Before and During the Covid 19 Pandemic at SMP Negeri 1 Losari Cirebon. Comparative research design with a research sample of 120 students. The sample in the study was taken by total sampling. The test instrument for measuring body mass index is measuring body weight with a kilogram scale and height with a meter in cm. Meanwhile, physical fitness is measured by the bleep test. The results of the study showed (1) There was an impact of learning sports and health physical education on body mass index before the covid 19 pandemic at SMP Negeri 1 Losari Cirebon (2) There was an impact of learning physical education sports and health on physical fitness before the covid 19 pandemic at SMP Negeri 1 Losari Cirebon.

The anomalous post-monsoon tropical cyclone (TC) Jawad has been simulated using the Coupled Ocean–Atmosphere Wave Sediment Transport (COAWST) model using Global Forecasting System (GFS) Analyses and Forecasts as the atmospheric initial and boundary conditions (IC and BC) along with two contrasting ocean IC and BCs, viz., HYCOM (experiment name GFS-HYCOM) and INCOIS (experiment name GFS-INCOIS), to evaluate the influence of TC Jawad on the ocean surface and sub-surface characteristics. Both experiments captured the track of the simulated TC, including its recurvature, with significant accuracy. Validation of surface and sub-surface temperatures from two buoys, (1) BD11 (west of the TC track) and (2) BD13 (east of the TC track) suggests that a proper contrast in temperature exists in the buoy observations between the two sides of the TC track with the eastern side—showing higher sub-surface warming, which is captured by GFS-HYCOM but with significant overestimation. The lower temperature on the western side of the TC track can be attributed to the weak upwelling associated with the cyclonic circulation caused by the interaction of the TC with the southward coastal currents. The vertical distribution of the temperature across the longitudes showed an unusually higher downwelling on the eastern side of the TC track suggesting the existence of a strong clockwise circulation near the location of BD13. This circulation was found to be more rigorous in GFS-HYCOM, which also simulated higher current magnitude in the sub-surface than GFS-INCOIS. Further analysis showed that the interaction of the cyclonic wind flow of TC Jawad (westerly) near the surface with the easterly flow caused the generation of the clockwise circulation over the ocean surface on the eastern side of the TC track leading to intense downwelling and warming of sub-surface temperature. This study highlights the importance of the employment of coupled ocean–atmosphere models to simulated TCs for a better understanding of the air–sea interaction processes and their responses to the passage of an anomalous TC like Jawad. [ABSTRACT FROM AUTHOR]

In order to quantitatively analyze the data measurement accuracy of ocean buoys under normal and extreme sea conditions, in this study, we simulated the six-degree-of-freedom motion response of self-designed ocean buoys under different sea conditions based on a separated vortex simulation and the fluid volume method and analyzed the impact of the unsteady motion of buoys on data measurement. The results indicate that under normal sea conditions, the deviation between the numerical method used in this paper and the experimental results is less than 10%. The heaving motion of a buoy is most sensitive to changes in wave conditions. The fluctuation intensity of buoy motion is modulated by the height and wavelength of waves. When the wave height and wavelength are similar to the overall geometric size of a buoy, the wave characteristics of the buoy's heave, yaw, and pitch motion are significant. In addition, under extreme sea conditions, the movement of the buoy can also cause a deviation in the measured velocity in the transverse flow direction, but the overall deviation is less than 10%. In extreme sea conditions, the wind speed measurement results should be corrected to improve the measurement accuracy of a buoy. [ABSTRACT FROM AUTHOR]

The suspended configuration of inter-array power cables between floating offshore wind turbines necessitates using various ancillary equipment, such as buoy elements and bend stiffeners, to maintain the desired cable geometry. The failure analysis is an important step in the design of an inter-array dynamic power cable layout. This study investigates the impact of buoy element failures on the structural integrity and fatigue life of inter-array power cable configurations in offshore environments, focusing on four environmental conditions representative of the North Sea. Utilizing numerical simulations and fatigue analysis in OrcaFlex, static and dynamic analyses are conducted to assess maximum tension, minimum bend radius (MBR), and fatigue life under single and two failure scenarios of buoy elements. The results indicate that single buoy failures significantly increase maximum tension at hang-off points. At the same time, MBR is found to be the smallest at the failure position, aiding in failure point identification. In addition, for the two buoy element failure scenarios, the maximum tension increase poses risks to structural integrity, while MBR and fatigue life have high sensitivity to the applied environmental conditions.

In base-station-based underwater wireless acoustic networks (B-UWANs), effective handover mechanisms are necessary to ensure seamless data services for mobile nodes such as autonomous underwater vehicles (AUVs). Unlike terrestrial base stations (BSs), moored buoy BSs in B-UWANs experience motion responses due to wave loads under environmental conditions, posing unique challenges to the handover process. This study examines how BS motion affects handover decision errors, which arise when AUVs incorrectly initiate handovers to unintended BSs due to BS motion. By utilizing the AUV–BS distance as a handover triggering parameter, our analysis reveals a significant increase in decision errors within the overlapping regions when both the current and target BSs are in motion, especially when moving in the same direction. In addition, these errors intensify with the magnitude of BS motion and are exacerbated by smaller BS network radii. Based on these simulation results, we present an analytical framework that not only measures the influence of BS motion on the AUV–BS distance but also provides strategic insights for refining underwater handover protocols, thereby enhancing operational reliability and service continuity in B-UWANs.

With the inception of the Argo program, the global ocean observation network is undergoing continuous advancement, with profiling buoys emerging as pivotal components of this network, thus garnering increased attention in research. In efforts to enhance the efficiency of profiling buoys and curtail energy consumption, a teardrop-shaped buoy design is proposed in this study. Moreover, an optimization methodology leveraging neural networks and genetic algorithms has been devised to attain an optimal profile curve. This curve seeks to minimize drag and drag coefficient while maximizing drainage, thereby improving hydrodynamic performance. Simulation-based validation and analysis are conducted to assess the efficacy of the optimized buoy design. Results indicate that the drag of the teardrop-shaped buoy with a deflector decreased by 9.2% compared to pre-optimized configurations and by 22% compared to buoys lacking deflectors. The hydrodynamic profile devised in this study effectively enhances buoy performance, laying a solid foundation for ocean thermal energy generation and buoyancy regulation control. Additionally, the optimized scheme serves as a valuable blueprint for the design of ocean exploration devices.

This study assesses wave energy by combining long-term model reanalysis data with in situ observations in a multi-island region. A buoy was deployed in the center area of the southern South China Sea (SCS) for 16 consecutive months. Neural network models are introduced to calibrate the significant wave height and the mean wave period of the European Center for Medium-Range Weather Forecasts (ECMWF) ERA5 reanalysis data. Based on the calibrated reanalysis data, wave energy potential in the region is assessed. The results show relatively available wave resources from October to February in climatology, with an average energy density higher than 5 kW m−1 and an available level frequency higher than 50%. Wave energy potential is relatively poor in other months. In the last 40 years, the wave energy density, available level frequency, and rich level frequency have shown significant increasing trends, consistent with the wind enhancement in the northeast SCS. It is suggested that the growth trend of waves in the northeast SCS may spread to the south region as swell propagation. The analysis emphasizes that there can be significant differences in the results of wave energy assessments, whether the data are calibrated or not. Therefore, the data accuracy needs to be fully evaluated when adopting model results for the planning and utilization of wave energy in such region.

This paper presents a novel method for the dynamic positioning of an unmanned underwater vehicle (UUV) with unknown trajectories based on an autonomous tracking buoy (PUVV-ATB) that indirectly positions the UUV using ultra-short baseline measurements. The method employs a spatial location geometric model and divides the positioning process into four steps, including data preprocessing to detect geometric errors and apply mean filtering, direction capture, position tracking, and position synchronization. To achieve these steps, a new adaptive tracking control algorithm is proposed that does not require trajectory prediction and is applied to the last three steps. The algorithm is deployed to the buoy for tracking simulation and sea trial experiments, and the results are compared with those of a model predictive control algorithm. The autonomous tracking buoy based on the adaptive tracking control algorithm runs more stably and can better complete the precise tracking task for the UUV with a positioning error of less than 10 cm. This method breaks the premise of trajectory prediction based on traditional tracking control algorithms, providing a new direction for further research on UUV localization. Furthermore, the conclusion of this paper has important reference value for other research and application fields related to UUV. [ABSTRACT FROM AUTHOR]

Sea level studies in the Mississippi Bight (MSB) are less abundant than in other coastal waters of USA. This study investigates the subinertial (time scales >2 days) sea level anomalies in the MSB shelf. The diagnostics of the terms in the invariant form of the momentum equation were computed to determine which terms have the most influence on the anomalies in sea level. It was determined that at subinertial scales the geostrophic balance is the dominant balance in the MSB while the non‐linear and time derivative terms are insignificant relative to the Coriolis term. A Least Squares procedure was applied to the subinertial surface currents data from high frequency radar surface currents (filtered with a window of 2‐day Butterworth filter) to extract subinertial sea level anomalies in the MSB shelf using both geostrophic balance and the invariant form of Reynolds' averaged momentum equations. The resulting subinertial sea level anomalies were validated using sea level observations from an offshore buoy and Sentinel‐3 along‐track satellite altimeter data. The estimated sea level anomalies were reasonably close to observations (more than half had root mean square difference of <0.04 m) and mostly influenced by geostrophic balance. Analysis of the empirical orthogonal functions showed that the first two modes explained the majority (85%) of the variance in the sea level anomalies estimated using the geostrophic approximation. Absolute sea level could be estimated if Global Navigation Satellite System buoys are deployed in the radar footprint. Plain Language Summary: Compared to other USA coastal waters, fewer sea level studies have been conducted in the Mississippi Bight (MSB). This study focuses on slow varying sea level anomalies with periods longer than 2 days. The terms in the equation governing the circulation in the MSB were evaluated using high frequency (HF) radar velocity data to determine which terms contributed the most to the sea level anomalies. The study demonstrated that the term associated to Earth's rotation has the largest amplitude implying that the dominant balance is between this term and the term related to sea level slope. Sea level anomalies estimated from both this dominant balance and the full governing equation by applying a Least Squares procedure. Buoy and Sentinel‐3 satellite altimeter sea level observations were used not only to validate the estimated sea level anomalies but also to confirm the validity of the dominant balance. Two major patterns of sea level spatiotemporal variability were determined. They accounted for 85% of the changes in the sea level anomalies. Additional observations within the HF radar coverage area such as high quality positioning data could be used to reference the estimated sea level anomalies. Key Points: At subinertial scales geostrophic balance is dominant in the Mississippi BightThe Least Squares procedure was used to estimate reliable sea level changes on the Mississippi Bight from surface current dataThere are two major patterns of Mississippi Bight sea level gradient determined from EOF [ABSTRACT FROM AUTHOR]

In the intricate realm of ocean-atmosphere dynamics, the sustained and stable operation of buoy observation systems under rough seas is crucial for ensuring marine resource security. This study employs a coupled Level-Set and Volume of Fluid (CLSVOF) method alongside the immersed boundary method. It investigates the physical processes of wind-wave interaction, the dynamic characteristics of cylindrical buoys, as well as the underlying mechanisms. The research highlights the significant impact of wave types (wind waves, swells) and wave steepness on the buoy's drift and oscillatory behavior. An increase in wave steepness and a shift from wind waves to swell markedly intensify both the buoy's drift and its oscillatory motions. Additionally, a thorough analysis of the loads on the buoy under varying maritime conditions is performed. By examining the vertical momentum equation on the windward and leeward sides, the secondary load cycle phenomenon is found to originate from collapse of the water column formed by the convergence of water flow behind the buoy. Wind waves are found to be less conducive to secondary load cycles compared to swell waves. Furthermore, the study investigates the relationship between the drag coefficient and the wave crest height on the windward side of the buoy, revealing a robust negative correlation between the two. This research not only illuminates the complex dynamics of wind-wave couplings but also offers theoretical insights for the optimization of buoy design. • Using high-fidelity numerical simulations to explore a cylindrical buoy's dynamic characteristics in ocean-atmosphere flows. • Study finds that the transition from wind waves to swells amplifies buoy motion due to reduced wind energy input. • Study identifies secondary load cycles' cause via force decomposition: decreased hydrostatic pressure at the cylinder's rear. • Research shows a strong correlation between wind and waves, with wave dynamics significantly affecting wind load on the buoy. [ABSTRACT FROM AUTHOR]

In order to quantitatively analyze the data measurement accuracy of ocean buoys under normal and extreme sea conditions, in this study, we simulated the six-degree-of-freedom motion response of self-designed ocean buoys under different sea conditions based on a separated vortex simulation and the fluid volume method and analyzed the impact of the unsteady motion of buoys on data measurement. The results indicate that under normal sea conditions, the deviation between the numerical method used in this paper and the experimental results is less than 10%. The heaving motion of a buoy is most sensitive to changes in wave conditions. The fluctuation intensity of buoy motion is modulated by the height and wavelength of waves. When the wave height and wavelength are similar to the overall geometric size of a buoy, the wave characteristics of the buoy’s heave, yaw, and pitch motion are significant. In addition, under extreme sea conditions, the movement of the buoy can also cause a deviation in the measured velocity in the transverse flow direction, but the overall deviation is less than 10%. In extreme sea conditions, the wind speed measurement results should be corrected to improve the measurement accuracy of a buoy.

In this paper, an ocean wave energy conversion system (OWECS) is modeled and experimented in the Yellow Sea near Lianyungang port, and an optimized control method based on the sliding mode control is proposed to improve the efficiency of OWECS. Firstly, a motion model of a double-buoy OWECS is presented using a complex representation method, and the analysis results indicate that the efficiency of converting ocean wave energy into the outer buoy's mechanical power is highest in a suitable ocean wave period. Secondly, a double-buoy OWECS is constructed and experimented in the Yellow Sea near Lianyungang port, which verified the correctness of the above analysis results. Lastly, in order to further improve the efficiency of the double-buoy OWECS, a sliding mode control method based on a linear generator is proposed to realize the phase synchronization between the outer buoy and ocean waves, and the simulation results may be beneficial for the next ocean test of the double-buoy OWECS. [ABSTRACT FROM AUTHOR]

The OMNI (Ocean Moored Buoy Network for northern Indian Ocean) buoy network comprises 12 buoy systems that measure surface meteorological parameters along with temperature and salinity profile measurements at discrete levels up to 500 m. All the OMNI buoy systems are deployed with slack-line moorings, which respond more to wind, wave, and current forcing compared to taut-line mooring. Subsurface temperature measurements are subject to change depending on both environmental condition and mooring design. The standard sensor fit of the OMNI buoy systems has only one pressure sensor fixed at 500 m, which shows significant depth variability. In order to see the spatial and seasonal variability in the vertical movement of the mooring line and the associated temperature variability, four deployments with additional pressure measurements at 200 m are analyzed. It is observed that the depth/temperature variability exhibits significant seasonality with maximum variability during pre-monsoon season. Also, the effect of this movement in the shallower depths is analyzed with four more pressure sensors in the mooring line for a 1-year period in the central Bay of Bengal. The analysis shows that the maximum value of average and root mean square (RMS) temperature deviations is 0.38 °C and 0.48 °C in the deepest interpolated depth at 400 m where the mooring line experiences a greater range of motion and the actual temperature variability in shallower depths is negligible particularly up to 75 m (<0.01°C). The study reveals the necessity of additional pressure measurements for better remapping of temperature profile measurements. [ABSTRACT FROM AUTHOR]

The skin sea surface temperature (SST) observed by the geostationary Himawari-8 satellite and bulk SST, including four in situ observations from ships, drifters, Argo, and buoys constitute more than 90,000 SST pairs used to analyze near-surface temperature variations. From July 2015 to May 2022, an average SST bias of 0.10 °C and root mean square error of 0.99 °C were observed in the waters adjacent to Taiwan. This study effectively observed that the skin effect generated by ocean wind and solar shortwave radiation caused the occurrence of a cool skin layer and diurnal warm layer (DWL), and 90% of the SST bias was in a range of −1.55~1.71 °C. In the daytime, the skin layer received solar shortwave radiation, thus increasing temperature and causing a DWL. With the increase in insolation, the SST bias in the DWL became more obvious. During winter, strong wind, or low shortwave radiation, the DWL may disappear and turn into a cool skin layer. At night, the near-surface SST was dominated by the cool skin effect, but the DWL generated in the daytime would remain if the wind speed was weak. However, the different hydrological characteristics of the observation position and its distance from the coast could affect the results of the skin effect. Whether there is a rapid change in ocean stratification in a spatial grid of nearly four square kilometers needs to be explored in the future. [ABSTRACT FROM AUTHOR]

Nutrient concentrations and its limited statuses can affect phytoplankton community structure and marine primary productivity. Identifying limiting nutrients under different ocean conditions, the causes, and the nature of such limitations, has important implications for understanding ecosystem changes and interpretation of in situ data. However, there is still a lack of retrieval methods for nutrients in seawater, especially in coastal waters. We propose to characterize the spatiotemporal variability of phytoplankton and nutrient-limited status in the surface ocean with diurnal valuevs of chlorophyll concentration. In this paper, the sediment fronts and plume fronts are used as a reference to select the relative and absolute nutrient-limited status regions. The variance of the six times per day (9:30-14:30) is calculated to represent the diurnal variation of chlorophyll, and the diurnal variation and concentration of chlorophyll combined are used to analyze nutrient-limited status. The results indicate that the diurnal variation of chlorophyll is greater after the typhoon, and the nutrient-limited status is different following each typhoon passing by. The in situ data shows that the highest chlorophyll a concentration reached 20.7 mg/m3 after the typhoon in August 2011.

We designed a hybrid system named Mooring Buoys Observation System with Benthic Electro-optical-mechanical Cable (MBOSBC) for long-term seafloor and sea surface multi-parameter ocean observation. The electro-optical-mechanical (EOM) cable connects a sea surface buoy and a seafloor junction box so as to establish a transmission link of information and power between the sea surface and the seafloor. The EOM cable also plays the role of mooring tether to the MBOSBC and has to withstand the rigorous marine environment—experiencing mooring loads under complex marine environmental conditions for long periods of time. The data transmission of the system includes the EOM, satellite communication, wireless radio, and acoustic communication. The system power is generated by a wind turbine and solar panels and is transmitted to the seafloor junction box. An acoustic communication instrument is used to gather the sample data from other benthic nodes, such as seafloor landers, AUVs, and underwater gliders. MBOSBC is designed to operate from shallow water to deep sea, and to simultaneously monitor sea surface hydrology, meteorology, and water quality, as well as benthic temperature, pressure, salinity, currents, and seafloor video. We provide the MBOSBC architecture design, including the mechanical design, control, power, data transmission, and EOM cable. Finally, we describe the launch and recovery process of MBOSBC, as well as experimental results.

In some sectors of the water resources management, the digital revolution process is slowed by some blocking factors such as costs, lack of digital expertise, resistance to change, etc. In addition, in the era of Big Data, many are the sources of information available in this field, but they are often not fully integrated. The adoption of different proprietary solutions to sense, collect and manage data is one of the main problems that hampers the availability of a fully integrated system. In this context, the aim of the project is to verify if a fully open, cost-effective and replicable digital ecosystem for lake monitoring can fill this gap and help the digitalization process using cloud based technology and an Automatic High-Frequency Monitoring System (AHFM) built using open hardware and software components. Once developed, the system is tested and validated in a real case scenario by integrating the historical databases and by checking the performance of the AHFM system. The solution applied the edge computing paradigm in order to move some computational work from server to the edge and fully exploiting the potential offered by low power consuming devices. [ABSTRACT FROM AUTHOR]

Ocean surface wind and wave information is important in a wide variety of areas, such as coastal disaster reduction, offshore structure design, and atmosphere‐ocean flux estimation. This study proposed a new method for ocean surface wind estimation from surface wave spectrum information measured by small global positioning system buoys. The concept of this method relies on the assumption that the high‐frequency part of the ocean‐wave spectrum is proportional to u∗f−4 ${u}_{\ast }{f}^{-4}$ where u∗ ${u}_{\ast }$ is the friction velocity and f $f$ is the frequency. The determination algorithm for the coefficient of f−4 ${f}^{-4}$ was optimized in this study. The wind direction was determined by the wave cross‐spectrum, assuming that the wind direction aligns the propagation direction of the high‐frequency part of the wave. The proposed wind estimation method was applied to bay and open ocean observations, and the performance of the proposed wind estimation method was similar between the bay and the open ocean. The proposed method improves the wind estimation especially in coastal areas and at high wind speeds in the open ocean compared with the previous method. The performance of the method of the previous study differs between the bay and open ocean due to their spectral shape differences. High‐quality wind and wave information can be obtained using the proposed method. If the mass deployment of small drifting buoys covered the global ocean, the information based on the proposed method could be considerably powerful, and could compensate for the weakness of satellite‐based wind and wave estimations. Plain Language Summary: Ocean observations are spatially sparse compared with on‐land observations because of the difficulty of observation platform development. However, ocean wind and wave information is important in a wide variety of areas, such as coastal disaster mitigation and offshore structure design. Recently, readily deployed small global positioning system (GPS)‐tracked buoys for wave observation have been developed that have the potential to fill gaps in observations through mass deployment. This study proposes a new ocean wind speed and direction estimation method using ocean wave information derived from a small GPS buoy. The performance of the proposed method was validated and compared with data of the observed wind. It was shown that the proposed method can be applied to any type of wave condition, whereas the applicability of the previous method was limited. The proposed method allows for high‐quality ocean wind and wave information to be simultaneously collected. Key Points: Ocean surface wind is estimated from ocean surface wave spectrum information measured by a small global positioning system buoyOcean surface wind is estimated from ocean surface waves for both bay and open ocean conditionsThe newly proposed method improves the accuracy of wind speed and direction estimations from ocean surface waves [ABSTRACT FROM AUTHOR]

Based on hourly data from 31 buoys in the offshore areas of China in 2020, the sea-surface wind products available from the High Resolution China Meteorological Administration Land Surface Data Assimilation System (HRCLDAS-V1.0) and the Fifth Generation Global Atmospheric Reanalysis (ERA5) dataset were evaluated. The results showed that both HRCLDAS-V1.0 and ERA5 sea-surface wind had high credibility in the offshore areas of China. Their wind speed mean absolute error (MAE) were 1.16 m/ s and 1.09 m/s respectively and wind direction MAE were 23 ° and 22 ° respectively. As wind intensity increased, their wind speed bias all became larger. When wind intensity level was greater than or equal to 10, the HRCLDAS-V1.0 wind speed was better than the ERA5 wind speed. In terms of wind direction, the accuracy of both improved with the increase of wind intensity. In addition, two typical cold air events in 2020 and Typhoon Bavi (2008) were used to examine the accuracy of HRCLDAS-V1.0 and ERA5 seasurface wind. Both HRCLDAS-V1.0 and ERA5 could reproduce the wind direction change caused by cold air events. However, there were some differences in wind speed during cold air events of different intensities. The HRCLDAS-V1.0 and ERA5 wind speed all had good performance when the wind speed was low during Typhoon Bavi. However, the performance of HRCLDAS-V1.0 was better than that of ERA5 for wind at peak intensity. [ABSTRACT FROM AUTHOR]

This paper presents a new energy harvesting method using a buckled beam with a piezoelectric layer inside a buoy. The buoy is designed as a hemispherical point energy absorber and is connected to the sea bed. Two piezoelectric harvesters are placed inside the buoy in horizontal and vertical directions to capture the rotational motion of water particles on the sea surface. Masses are added to the middle of the beams to enhance the system's harvesting behavior. The equations of motion of the system are obtained using the Hamilton principle. These six coupled non-linear equations are solved using the Runge-Kutta numerical method. The dynamic behavior of the buoy and the buckled beam and the energy harvesting system's electrical behavior are analyzed. An analytical method of complexification-averaging is also examined and found to produce results similar to those of the numerical method. A simplified finite element model is presented to show that the displacement magnitude peak of the response obtained in the numerical solution method can be accepted. The study investigates the effects of limited changes in parameters such as frequency and amplitude of waves, electrical circuit resistance, piezoelectric layer characteristics, and buckled beam characteristics on the system behavior. It is shown that wave amplitude has a more significant role in energy production. [ABSTRACT FROM AUTHOR]

• Hong Kong Observatory operates ocean model in support of marine weather forecasting • Model validation of current and wave forecasts uses moored and drifting buoys data • Downscaling model results serve as benchmark reference for future model enhancement The Hong Kong Observatory has been running an Operational Marine Forecasting System (OMFS) adapted from the Regional Ocean Modelling System (ROMS) coupled with the WaveWatch III and SWAN wave models to provide wave, current and sea temperature forecasts up to 144 h twice a day since December 2021. To facilitate users' interpretation of model forecasts of significant wave height and current speed in coastal predictions and open seas which are of particular significance in high wind situations, model forecasts were validated against moored buoy observations and wave recorder measurements near the shores of Hong Kong and drifting buoy data over the South China Sea, as well as Mercator Ocean model reanalysis in 2022. The validation results showed that the wave forecasts generally agreed well with the buoy observations with coefficient of determination (R2) of around 0.7 and root-mean-square error (RMSE) of less than 0.2 m up to 72 h ahead. The R2 for sea current forecasts ranged between 0.4 and 0.6, and the RMSE was around 8 to 11 cm/s in near shores up to T + 144 forecast hours. Validation against drifting buoy demonstrated that the trend of current forecasts generally agreed well with the measurements. RMSE of surface current forecasts over open seas ranged from 19 cm/s for 24-hour forecast to around 30 cm/s for 144-hour forecast when compared against Mercator Ocean reanalysis. Results from the current downscaling approach could serve as a benchmark reference for HKO to enhance OMFS in the future. In this paper, applications of model forecasts in the provision of marine weather services in Hong Kong are also introduced. [ABSTRACT FROM AUTHOR]

This paper presents a novel method for the dynamic positioning of an unmanned underwater vehicle (UUV) with unknown trajectories based on an autonomous tracking buoy (PUVV-ATB) that indirectly positions the UUV using ultra-short baseline measurements. The method employs a spatial location geometric model and divides the positioning process into four steps, including data preprocessing to detect geometric errors and apply mean filtering, direction capture, position tracking, and position synchronization. To achieve these steps, a new adaptive tracking control algorithm is proposed that does not require trajectory prediction and is applied to the last three steps. The algorithm is deployed to the buoy for tracking simulation and sea trial experiments, and the results are compared with those of a model predictive control algorithm. The autonomous tracking buoy based on the adaptive tracking control algorithm runs more stably and can better complete the precise tracking task for the UUV with a positioning error of less than 10 cm. This method breaks the premise of trajectory prediction based on traditional tracking control algorithms, providing a new direction for further research on UUV localization. Furthermore, the conclusion of this paper has important reference value for other research and application fields related to UUV.

Savasta, D.; Nucera, A.; Barbaro, G., and Foti, G., 2022. A new geographic transfer method of wave data. Journal of Coastal Research, 38(3), 557–566. Coconut Creek (Florida), ISSN 0749-0208. The availability of quality, site-specific wave data is necessary for an accurate understanding of wave climate. Direct and indirect wave data often have insufficient spatial resolution to ensure the requirement for geographic representativeness of data. The proposed wave data transfer method, in two versions, transfers an entire time series of wave data from a point with data to a neighboring point. The method is based on the empirical relationships of the Shore Protection Manual method and involves estimating appropriate statistical parameters from wind data characterizing the area comprising the two points. The method has been tested and compared with De Girolamo and Contini's transfer method in three applications in the Mediterranean Sea, showing significantly better results in two applications and similar results in a third application. It is believed that the lower reliability of the new transfer method in one of the three applications results from the considerable distance, 112 km, between the data point and the transfer point. Transfer methods are more accurate in cases of modest distances between the two points, which is the classic application of the transfer method in engineering practice. [ABSTRACT FROM AUTHOR]

In the existing research on the intelligent navigation of ships, navigation route planning often regards light buoys as fixed obstructions. However, due to factors such as water ripples, the position of the buoys keeps periodically changing. If the buoys are set to a fixed range of avoidance areas in the process of ship navigation, it is easy to allow a collision between the ship and the light buoys. Therefore, based on historical motion trajectory data of the buoys, a SARIMA-based time-series prediction model is proposed to estimate the offset position of a given buoy in a specified time. Furthermore, the collision-free path planning approach is presented to dynamically recommend an accurate sailing path. The results of the simulation experiment show that this method can effectively deal with collisions of ships caused by the offset position of the light buoys during the navigation of the large and low-speed autonomous ships. [ABSTRACT FROM AUTHOR]

Floating offshore structures (FOS) must be designed to be stable, to float, and to be able to support other structures for which they were designed. These FOS are needed for different transfer operations in oil terminals. However, water waves affect the motion response of floating buoys. Under normal sea states, the free-floating buoy presents stable periodic responses. However, when moored, they are kept in position. Mooring configurations used to moor buoys in single point mooring (SPM) terminals could require systems such as Catenary Anchor Leg Moorings (CALM) and Single Anchor Leg Moorings (SALM). The CALM buoys are one of the most commonly-utilised type of offshore loading terminal. Due to the wider application of CALM buoy systems, it is necessary to investigate the fluid structure interaction (FSI) and vortex effect on the buoy. In this study, a numerical investigation is presented on a CALM buoy model conducted using Computational Fluid Dynamics (CFD) in ANSYS Fluent version R2 2020. Some hydrodynamic definitions and governing equations were presented to introduce the model. The results presented visualize and evaluate specific motion characteristics of the CALM buoy with emphasis on the vortex effect. The results of the CFD study present a better understanding of the hydrodynamic parameters, reaction characteristics and fluid-structure interaction under random waves. [ABSTRACT FROM AUTHOR]

Topo-bathymetric surveys are mostly desired in coastal area where water and land perpetually interact. This work explore the ground-based methods of topographic and bathymetric surveys in collecting data for the appropriate description of the Mayegun Estate water front and the adjoining land topography. To acquire depth data at pre-defined transects lines, hydrographic vessel and a trained diver were engaged. The topo-bathy DEM was produced at 1m and contour at 0.5m interval. The wave pattern was determined to be semi-diurnal. The fitted second order polynomial regression equation for wave amplitude against time yielded (y = 2E-07x² - 0.0003x - 0.0276 at R² = 0.0064) while that of depth versus sounded points gave (y = 5E-09x² - 5E-06x - 7.1512) at R² = 0.0019. The vertical and horizontal uncertainties were computed as 0.015m and 5m + (-0.47) at 95% confidence level based on (IHO) specification for order 1a. This principle can be adopted with caution as a viable alternative for topo-bathy surveys to minimize cost. [ABSTRACT FROM AUTHOR]

This paper is an introduction to the issue of buoys, i.e. signs normally produced with the non-dominant hand to ensure a spatial reference point for signs produced with the dominant hand. Simultaneous constructions of this type have been noticed in numerous sign languages, yet their equivalents have not been described in any detail for Polish Sign Language (PJM). The paper presents what can be said about the use of buoys in PJM on the basis of an analysis of a collection of empirical data extracted from the Corpus of Polish Sign Language (KPJM). The research confirms that certain buoy types (fragment and depicting buoys) are frequent in PJM and can be found in recurring contexts, which speaks for considering them as a part of grammar of this language. [ABSTRACT FROM AUTHOR]