2025 Vol. 47, No. 2
Display Method:
2025, 47(2): 1-14.
doi: 10.12284/hyxb2025001
Abstract:
Underwater target detection is an important part of China’s “transparent ocean” project. However, due to the complex and ever-changing underwater environment, achieving accurate and efficient detection of underwater targets remains a significant challenge. As a fixed offshore platform across the sea, the buoy is an important part of building a comprehensive and three-dimensional detection network, which can simultaneously meet the all-weather monitoring requirements of key locations in the ocean and achieve real-time information transmission, complementing more accurate and real-time underwater target information acquisition methods. Based on the summary of existing underwater target detection methods based on buoys, this article introduces optical detection, electromagnetic detection, communication relay, and other underwater target detection and information transmission technologies. It also combs and analyzes relevant technologies in combination with the application characteristics of buoys, with a view to providing useful inspiration and reference for the research and application of underwater target detection technology based on buoys.
Underwater target detection is an important part of China’s “transparent ocean” project. However, due to the complex and ever-changing underwater environment, achieving accurate and efficient detection of underwater targets remains a significant challenge. As a fixed offshore platform across the sea, the buoy is an important part of building a comprehensive and three-dimensional detection network, which can simultaneously meet the all-weather monitoring requirements of key locations in the ocean and achieve real-time information transmission, complementing more accurate and real-time underwater target information acquisition methods. Based on the summary of existing underwater target detection methods based on buoys, this article introduces optical detection, electromagnetic detection, communication relay, and other underwater target detection and information transmission technologies. It also combs and analyzes relevant technologies in combination with the application characteristics of buoys, with a view to providing useful inspiration and reference for the research and application of underwater target detection technology based on buoys.
2025, 47(2): 15-28.
doi: 10.12284/hyxb2025017
Abstract:
The surf zone eddies play a vital role in material transport, coastal morphology, and ecological environment. However, the formation mechanisms and evolution characteristics of surf zone eddies, especially their spatiotemporal evolution under strong wave-induced currents, remain insufficiently understood. This study integrates pollutant tracer experiments and numerical simulations using the Funwave model based on the Boussinesq equations to investigate the evolution of surf zone eddies under strong wave-driven currents. The experimental results demonstrate that under strong wave-induced currents, large-scale eddies emerge on both the onshore and offshore sides of the surf zone, exhibiting transient behavior. These eddies detach from the pollutant patches, with the onshore eddies constrained by the shoreline, while the offshore eddies gradually evolve and exhibit a tendency to migrate outward beyond the surf zone. The numerical simulations indicate that strong eddies concentrate near the breaking line, with the surf zone eddy field characterized by upstream and downstream shear zones, both exhibiting similar alongshore spacing and eddy structures. Vorticity positively correlates with wave height and period, and the stronger eddies are shifted to the seaward side. Under irregular wave conditions, vorticity decreases, accompanied by a shoreward shift in the locations of maximum vorticity.
The surf zone eddies play a vital role in material transport, coastal morphology, and ecological environment. However, the formation mechanisms and evolution characteristics of surf zone eddies, especially their spatiotemporal evolution under strong wave-induced currents, remain insufficiently understood. This study integrates pollutant tracer experiments and numerical simulations using the Funwave model based on the Boussinesq equations to investigate the evolution of surf zone eddies under strong wave-driven currents. The experimental results demonstrate that under strong wave-induced currents, large-scale eddies emerge on both the onshore and offshore sides of the surf zone, exhibiting transient behavior. These eddies detach from the pollutant patches, with the onshore eddies constrained by the shoreline, while the offshore eddies gradually evolve and exhibit a tendency to migrate outward beyond the surf zone. The numerical simulations indicate that strong eddies concentrate near the breaking line, with the surf zone eddy field characterized by upstream and downstream shear zones, both exhibiting similar alongshore spacing and eddy structures. Vorticity positively correlates with wave height and period, and the stronger eddies are shifted to the seaward side. Under irregular wave conditions, vorticity decreases, accompanied by a shoreward shift in the locations of maximum vorticity.
2025, 47(2): 29-40.
doi: 10.12284/hyxb2025011
Abstract:
Due to the limitations of the Rayleigh criterion, classical harmonic analysis (CHA) model requires half a year of data records to analyze the eight main tidal constituents, namely, M2, S2, N2, K2, K1, O1, P1, Q1. For short-term tidal records, the unresolved constituents typically rely on the ratio differences from nearby long-term tidal stations for estimation. However, there is a scarcity of publicly available long-term tidal data in the coastal areas of Zhejiang, which currently prevents the accurate extraction of the main constituents from short-term records. This paper introduces a modified harmonic analysis model, referred to as the Modified Harmonic Analysis model based on the Credo of Smoothness (MHACS). Based on the smooth functions established by the intrinsic connections between major constituents, it breaks through the Rayleigh criterion, significantly reducing the length of tidal records required, especially suitable for coastal areas with abundant short-term data. This algorithm was applied to the multi-island area of Zhejiang offshore, using tidal records shorter than 15 days. The results show that the harmonic constants of the eight main constituents at the Shipu station are very close to the results obtained by the CHA method, and the required data length is reduced from8760 hours to 336 hours, which can be used to calculate characteristic parameters such as the theoretical depth datum. For analyzing the eight main constituents along the Zhejiang coast using MHACS, a minimum data length of 5 days is recommended.
Due to the limitations of the Rayleigh criterion, classical harmonic analysis (CHA) model requires half a year of data records to analyze the eight main tidal constituents, namely, M2, S2, N2, K2, K1, O1, P1, Q1. For short-term tidal records, the unresolved constituents typically rely on the ratio differences from nearby long-term tidal stations for estimation. However, there is a scarcity of publicly available long-term tidal data in the coastal areas of Zhejiang, which currently prevents the accurate extraction of the main constituents from short-term records. This paper introduces a modified harmonic analysis model, referred to as the Modified Harmonic Analysis model based on the Credo of Smoothness (MHACS). Based on the smooth functions established by the intrinsic connections between major constituents, it breaks through the Rayleigh criterion, significantly reducing the length of tidal records required, especially suitable for coastal areas with abundant short-term data. This algorithm was applied to the multi-island area of Zhejiang offshore, using tidal records shorter than 15 days. The results show that the harmonic constants of the eight main constituents at the Shipu station are very close to the results obtained by the CHA method, and the required data length is reduced from
2025, 47(2): 41-55.
doi: 10.12284/hyxb2025003
Abstract:
Snow ice is the product of the transformation from snow into sea ice, which plays an important role in the change of sea ice structure. Studying the spatial and temporal variations of snow ice can provide deep insights into the “snow-ice” transformation process and help understand the evolution of sea ice and polar climate changes. This paper utilizes the EC-Earth3 model to analyze snow ice and its influencing factors in both historical simulations (1990−2014) and Shared Socioeconomic Pathways SSP245 projections (2015−2100). The spatiotemporal evolution of snow ice growth in historical and future periods was investigated by statistical methods such as ensemble averaging, regression analysis, and Mann-Kendall trend test. Compared with the satellite observation sea ice density data of the National Ice and Snow Data Center, the results indicate that the EC-Earth3 model performs well in reconstructing the observed sea ice, and hence provides confidence in projecting the future ice variation. Snow ice primarily forms in winter and spring, with distribution in the Davis Strait, the Nordic Seas, and the northern Barents Sea. The average decrease trend of snow ice growth is 7.4 × 108 kg/a; the change of the average sea ice outer edge line is about 1 kg/m2 in spring and winter; the highest proportion of snow ice is in the southeast of Greenland with an average of about 2%. Increased snowfall, rainfall and rising temperatures are important factors affecting snow ice formation. Future projections suggest that the generation of snow ice is still mainly concentrated in spring and winter, and the total amount of snow ice growth will decrease by 2.6 × 108 kg/a on average; due to the increase of precipitation and temperature increase, the maximum increase trend of snow ice annual in March in the study area is 0.7 kg/m2, and the proportion of snow ice in ice thickness increases year by year. The analysis of future scenario experiment results has important scientific reference value for the development and utilization of Arctic waterway and the design of icebreaker capacity.
Snow ice is the product of the transformation from snow into sea ice, which plays an important role in the change of sea ice structure. Studying the spatial and temporal variations of snow ice can provide deep insights into the “snow-ice” transformation process and help understand the evolution of sea ice and polar climate changes. This paper utilizes the EC-Earth3 model to analyze snow ice and its influencing factors in both historical simulations (1990−2014) and Shared Socioeconomic Pathways SSP245 projections (2015−2100). The spatiotemporal evolution of snow ice growth in historical and future periods was investigated by statistical methods such as ensemble averaging, regression analysis, and Mann-Kendall trend test. Compared with the satellite observation sea ice density data of the National Ice and Snow Data Center, the results indicate that the EC-Earth3 model performs well in reconstructing the observed sea ice, and hence provides confidence in projecting the future ice variation. Snow ice primarily forms in winter and spring, with distribution in the Davis Strait, the Nordic Seas, and the northern Barents Sea. The average decrease trend of snow ice growth is 7.4 × 108 kg/a; the change of the average sea ice outer edge line is about 1 kg/m2 in spring and winter; the highest proportion of snow ice is in the southeast of Greenland with an average of about 2%. Increased snowfall, rainfall and rising temperatures are important factors affecting snow ice formation. Future projections suggest that the generation of snow ice is still mainly concentrated in spring and winter, and the total amount of snow ice growth will decrease by 2.6 × 108 kg/a on average; due to the increase of precipitation and temperature increase, the maximum increase trend of snow ice annual in March in the study area is 0.7 kg/m2, and the proportion of snow ice in ice thickness increases year by year. The analysis of future scenario experiment results has important scientific reference value for the development and utilization of Arctic waterway and the design of icebreaker capacity.
2025, 47(2): 56-68.
doi: 10.12284/hyxb2025014
Abstract:
This study compiled data on the 239+240Pu concentration or specific ratio-activity, 240Pu/239Pu atom ratio, and 239+240Pu flux or inventory in seawater, corals, shells and sediment samples in the northern South China Sea. The 239+240Pu sources and trends in surface seawater, water columns, surface sediments, and sediment cores in this area were presented. According to the two end member model, global fallout (GF) and the Pacific Proving Grounds (PPG) were currently the sources of 239+240Pu in environmental samples investigated from the northern South China Sea. Meanwhile, according to the migration model, it was found for the first time that a positive linear relationship between the water depth corresponding to the 239+240Pu peak concentration in the water column and its migration rate. The correlation between the organic matter content or particle size of surface sediments and the 239+240Pu specific ratio-activity had a segmented nature, showing positive and negative correlations, respectively. The numerical result of the 239+240Pu chrono-marker sedimentation rate in sediment core samples was usually greater than or equal to the maximum apparent diffusion rate of relatively exchangeable 239+240Pu in the same core sample, and there was a significant positive linear relationship between the sedimentation rate and the maximum apparent diffusion rate, the impact of the maximum apparent diffusion rate of relatively exchangeable 239+240Pu in the core sample on the sedimentation rate can be ignored.
This study compiled data on the 239+240Pu concentration or specific ratio-activity, 240Pu/239Pu atom ratio, and 239+240Pu flux or inventory in seawater, corals, shells and sediment samples in the northern South China Sea. The 239+240Pu sources and trends in surface seawater, water columns, surface sediments, and sediment cores in this area were presented. According to the two end member model, global fallout (GF) and the Pacific Proving Grounds (PPG) were currently the sources of 239+240Pu in environmental samples investigated from the northern South China Sea. Meanwhile, according to the migration model, it was found for the first time that a positive linear relationship between the water depth corresponding to the 239+240Pu peak concentration in the water column and its migration rate. The correlation between the organic matter content or particle size of surface sediments and the 239+240Pu specific ratio-activity had a segmented nature, showing positive and negative correlations, respectively. The numerical result of the 239+240Pu chrono-marker sedimentation rate in sediment core samples was usually greater than or equal to the maximum apparent diffusion rate of relatively exchangeable 239+240Pu in the same core sample, and there was a significant positive linear relationship between the sedimentation rate and the maximum apparent diffusion rate, the impact of the maximum apparent diffusion rate of relatively exchangeable 239+240Pu in the core sample on the sedimentation rate can be ignored.
2025, 47(2): 69-84.
doi: 10.12284/hyxb2025015
Abstract:
Beach erosion under the influence of frequent and severe storm events is generally increasing. Understanding the process of beach profile change under the influence of storm events is essential for the protection of sandy coast erosion. To clarify the response characteristics of the embayed beach profile to the storm, this study combined field observation during the typhoon and the XBeach model to reveal the profile morphological changes of the Dongsha beach in Zhujiajian Island, Zhejiang Province, under the influence of typhoon Tapah, and the influence of different factors on the beach storm response was discussed. The main results are as follows. Under the influence of typhoon Tapah, the profile of the Dongsha beach showed a significant pattern of erosion in the upper part of the profile and accretion in the lower part, and there was almost no change in the topography on the seaward side of the 400 m offshore (sand-mud transition). The calculation of different storm scenarios shows that the significant wave height controls the erosion and deposition amplitude of the profile, while the tidal level controls the position of erosion and deposition on the profile. When the storm wave height is large, the difference in profile changes caused by different settings of fine to medium sand grain size range is small. The offshore distance of the stop point of profile change is farther when there is beach nourishment. The results of this study can provide a scientific reference for the protection of storm erosion in the sandy coast.
Beach erosion under the influence of frequent and severe storm events is generally increasing. Understanding the process of beach profile change under the influence of storm events is essential for the protection of sandy coast erosion. To clarify the response characteristics of the embayed beach profile to the storm, this study combined field observation during the typhoon and the XBeach model to reveal the profile morphological changes of the Dongsha beach in Zhujiajian Island, Zhejiang Province, under the influence of typhoon Tapah, and the influence of different factors on the beach storm response was discussed. The main results are as follows. Under the influence of typhoon Tapah, the profile of the Dongsha beach showed a significant pattern of erosion in the upper part of the profile and accretion in the lower part, and there was almost no change in the topography on the seaward side of the 400 m offshore (sand-mud transition). The calculation of different storm scenarios shows that the significant wave height controls the erosion and deposition amplitude of the profile, while the tidal level controls the position of erosion and deposition on the profile. When the storm wave height is large, the difference in profile changes caused by different settings of fine to medium sand grain size range is small. The offshore distance of the stop point of profile change is farther when there is beach nourishment. The results of this study can provide a scientific reference for the protection of storm erosion in the sandy coast.
2025, 47(2): 85-97.
doi: 10.12284/hyxb2025013
Abstract:
Three-dimensional (3D) geological models enable the intuitive representation of seabed geological conditions through using marine survey data, which actively promotes the development and construction of offshore wind farms. To enhance the accuracy and modelling efficiency of 3D geological models for offshore wind farms, a geological modelling method is proposed based on multi-source data fusion. This method conducts an integrated interpretation of geotechnical investigation data and engineering geophysical data, employs spatial interpolation algorithms to generate continuous and smooth layer interfaces, and utilizes Python open-source libraries to construct and visualize the 3D geological models. Furthermore, taking an offshore wind farm in eastern Guangdong as an example, the reliability of the geological modelling method is validated. The results demonstrate that the method achieves the effective integration of geotechnical and geophysical data, and the constructed 3D geological model could reflect the complex geological characteristics of the offshore wind farm. The proposed 3D geological modelling method is applicable to a diverse range of engineering geological conditions, providing solid technical support for the full lifecycle management of offshore wind farms, from exploration, design, installation, operation and maintenance to decommissioning.
Three-dimensional (3D) geological models enable the intuitive representation of seabed geological conditions through using marine survey data, which actively promotes the development and construction of offshore wind farms. To enhance the accuracy and modelling efficiency of 3D geological models for offshore wind farms, a geological modelling method is proposed based on multi-source data fusion. This method conducts an integrated interpretation of geotechnical investigation data and engineering geophysical data, employs spatial interpolation algorithms to generate continuous and smooth layer interfaces, and utilizes Python open-source libraries to construct and visualize the 3D geological models. Furthermore, taking an offshore wind farm in eastern Guangdong as an example, the reliability of the geological modelling method is validated. The results demonstrate that the method achieves the effective integration of geotechnical and geophysical data, and the constructed 3D geological model could reflect the complex geological characteristics of the offshore wind farm. The proposed 3D geological modelling method is applicable to a diverse range of engineering geological conditions, providing solid technical support for the full lifecycle management of offshore wind farms, from exploration, design, installation, operation and maintenance to decommissioning.
2025, 47(2): 98-107.
doi: 10.12284/hyxb2025027
Abstract:
This article explores the distinctive marine environment of the West African coastal region, with a particular focus on bimodal waves-induced seabed response and stability around sloping breakwaters. Bimodal waves are a unique wave pattern observed in the West African Sea, influenced by distant swells from the North Atlantic. These waves present new challenges in marine engineering, particularly in the design and maintenance of breakwater structures. A complex numerical model has been developed to simulate the interaction between bimodal spectrum random waves and sloping breakwaters. This model is grounded in the Reynolds-averaged Navier-Stokes equations and employs the k-ω turbulence model to simulate the flow field and pressure distribution around the breakwater. Furthermore, the model incorporates Biot’s semi-dynamic porous medium theory (the u-p model) to assess wave-induced pore pressure and the liquefaction features of the seabed. The study found that the pore pressure response varies under different conditions, generally indicating that pore pressure increases with the swell energy ratio (SER). It was observed that low-frequency pore pressure becomes more pronounced with increasing depth and swell wave ratio. Analyzing the swell energy ratio revealed that the attenuation rate of low-frequency energy is lower than that of high-frequency energy. As the swell energy ratio increases, the pore pressure response in the seabed intensifies significantly, leading to an expansion in the range and depth of seabed liquefaction, especially noticeable at certain distances in front of the breakwater. Furthermore, the influence of high-frequency and low-frequency pore pressure on seabed liquefaction alternates with the increasing distance from the breakwater’s toe. This study provides a scientific basis for the design and stability assessment of sloping breakwaters.
This article explores the distinctive marine environment of the West African coastal region, with a particular focus on bimodal waves-induced seabed response and stability around sloping breakwaters. Bimodal waves are a unique wave pattern observed in the West African Sea, influenced by distant swells from the North Atlantic. These waves present new challenges in marine engineering, particularly in the design and maintenance of breakwater structures. A complex numerical model has been developed to simulate the interaction between bimodal spectrum random waves and sloping breakwaters. This model is grounded in the Reynolds-averaged Navier-Stokes equations and employs the k-ω turbulence model to simulate the flow field and pressure distribution around the breakwater. Furthermore, the model incorporates Biot’s semi-dynamic porous medium theory (the u-p model) to assess wave-induced pore pressure and the liquefaction features of the seabed. The study found that the pore pressure response varies under different conditions, generally indicating that pore pressure increases with the swell energy ratio (SER). It was observed that low-frequency pore pressure becomes more pronounced with increasing depth and swell wave ratio. Analyzing the swell energy ratio revealed that the attenuation rate of low-frequency energy is lower than that of high-frequency energy. As the swell energy ratio increases, the pore pressure response in the seabed intensifies significantly, leading to an expansion in the range and depth of seabed liquefaction, especially noticeable at certain distances in front of the breakwater. Furthermore, the influence of high-frequency and low-frequency pore pressure on seabed liquefaction alternates with the increasing distance from the breakwater’s toe. This study provides a scientific basis for the design and stability assessment of sloping breakwaters.
2025, 47(2): 108-130.
doi: 10.12284/hyxb2025005
Abstract:
High-quality in situ measurement data is a prerequisite for the validation of ocean color remote sensing data products, algorithm development, and climate change research. The collection of in situ measurement data, however, typically requires a substantial investment of human, material and financial resources. The data collected by a single research team often insufficient to support long-term and large-scale research. Driven by the advances in scientific research of “big data”, several open-access data platforms, intergovernmental and national marine scientific data centers, as well as database platforms of major marine-related departments, have released diverse types of in-situ measurement data and shared them with users. This is aimed at giving full play to the value of in-situ measurement data and supporting the research on major scientific issues. It is difficult for data users to quickly understand and apply shared data from these platforms, because of the discrete distribution of datasets on different platforms, and differences in data collection time, regions, disciplinary categories, and acquisition methods. This results in a time-consuming and labor-intensive process of gathering relevant research data. Therefore, this paper compiles and organizes 29 database platforms from which parameters such as ocean optics, biogeochemistry can be obtained. These platforms store in-situ measurement data from the global ocean over the past century. This paper reviews the typical applications of these shared data in the research of ocean color remote sensing, and provides suggestions for data retrieval of commonly used parameters, with the aim of helping data users obtain research data quickly.
High-quality in situ measurement data is a prerequisite for the validation of ocean color remote sensing data products, algorithm development, and climate change research. The collection of in situ measurement data, however, typically requires a substantial investment of human, material and financial resources. The data collected by a single research team often insufficient to support long-term and large-scale research. Driven by the advances in scientific research of “big data”, several open-access data platforms, intergovernmental and national marine scientific data centers, as well as database platforms of major marine-related departments, have released diverse types of in-situ measurement data and shared them with users. This is aimed at giving full play to the value of in-situ measurement data and supporting the research on major scientific issues. It is difficult for data users to quickly understand and apply shared data from these platforms, because of the discrete distribution of datasets on different platforms, and differences in data collection time, regions, disciplinary categories, and acquisition methods. This results in a time-consuming and labor-intensive process of gathering relevant research data. Therefore, this paper compiles and organizes 29 database platforms from which parameters such as ocean optics, biogeochemistry can be obtained. These platforms store in-situ measurement data from the global ocean over the past century. This paper reviews the typical applications of these shared data in the research of ocean color remote sensing, and provides suggestions for data retrieval of commonly used parameters, with the aim of helping data users obtain research data quickly.
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