2024 Vol. 46, No. 4
Display Method:
2024, 46(4): 1-12.
doi: 10.12284/hyxb2024009
Abstract:
Plastic floating objects have a profound impact on the marine environment. The nearshore process of the floating objects is mainly influenced by the action of waves. On the kinetic characteristics of plastic floating objects, previous studies were not thorough for the nearshore regime. In this paper, laboratory experiments were used to study the drift-law of plastic-floating objects under finite-water-depth waves. The relationship between the horizontal drift velocity of a weakly inertial plastic blocks and their characteristics, along with the wave steepness were discussed. The experimental results show that the drift of plastic blocks is affected by Stokes drift and Euler return flow, which is in good agreement with the second-order Lagrange drift theory. As the floating object’s size is much smaller than the wave length, size or density of the floating objects has no significant effect on drift. The drift of floating objects is proportional to the square of wave steepness. Based on the experiments conducted in this study and previously published experimental data, the empirical formula is revised to provide useful reference for the nearshore migration law of plastic floating objects and so for the relevant prediction.
Plastic floating objects have a profound impact on the marine environment. The nearshore process of the floating objects is mainly influenced by the action of waves. On the kinetic characteristics of plastic floating objects, previous studies were not thorough for the nearshore regime. In this paper, laboratory experiments were used to study the drift-law of plastic-floating objects under finite-water-depth waves. The relationship between the horizontal drift velocity of a weakly inertial plastic blocks and their characteristics, along with the wave steepness were discussed. The experimental results show that the drift of plastic blocks is affected by Stokes drift and Euler return flow, which is in good agreement with the second-order Lagrange drift theory. As the floating object’s size is much smaller than the wave length, size or density of the floating objects has no significant effect on drift. The drift of floating objects is proportional to the square of wave steepness. Based on the experiments conducted in this study and previously published experimental data, the empirical formula is revised to provide useful reference for the nearshore migration law of plastic floating objects and so for the relevant prediction.
2024, 46(4): 13-22.
doi: 10.12284/hyxb2024037
Abstract:
This study used ERA5 reanalysis data to collect an extreme wave event dataset for various regions in the Arctic Ocean during August to October from 1979 to 2021. The analysis focused on the frequency of extreme wave events, changes in extreme wave heights, features of wave power and wave direction distribution, as well as the change of sea ice during wave events. The results suggest that as sea ice decreases, the range of extreme wave activity in the Arctic expands. All regions, except the Barents Sea, exhibit an increase in the occurrence of extreme wave events. In particular, extreme wave heights in the East Siberian Sea and Laptev Sea have significantly increased at rates of approximately 3.5 cm/a and 2 cm/a, respectively, with event frequency reaching around 4 events per year. The dominant wave direction in the Laptev Sea is southerly, facilitating more frequent wave propagation into the ice zone compared to other seas, with an average wave energy flux ranging from 5−8 kW/m. The changes in sea ice within extreme wave events primarily occur in the marginal ice zones and are associated with wind direction: sea ice is more likely to decrease with on-ice winds, while it is more likely to increase with off-ice winds.
This study used ERA5 reanalysis data to collect an extreme wave event dataset for various regions in the Arctic Ocean during August to October from 1979 to 2021. The analysis focused on the frequency of extreme wave events, changes in extreme wave heights, features of wave power and wave direction distribution, as well as the change of sea ice during wave events. The results suggest that as sea ice decreases, the range of extreme wave activity in the Arctic expands. All regions, except the Barents Sea, exhibit an increase in the occurrence of extreme wave events. In particular, extreme wave heights in the East Siberian Sea and Laptev Sea have significantly increased at rates of approximately 3.5 cm/a and 2 cm/a, respectively, with event frequency reaching around 4 events per year. The dominant wave direction in the Laptev Sea is southerly, facilitating more frequent wave propagation into the ice zone compared to other seas, with an average wave energy flux ranging from 5−8 kW/m. The changes in sea ice within extreme wave events primarily occur in the marginal ice zones and are associated with wind direction: sea ice is more likely to decrease with on-ice winds, while it is more likely to increase with off-ice winds.
2024, 46(4): 23-33.
doi: 10.12284/hyxb2024033
Abstract:
Submesoscale processes associated with strong vertical velocities play significant roles in the vertical transport of tracers between the ocean surface and the interior, including heat, buoyancy, and mass. Based on the results of the (1/48)° LLC4320 model, this study investigates the seasonal variations of submesoscale vertical heat transport in the Kuroshio Extension. The results show that submesoscale vertical heat transport in the Kuroshio Extension exhibits distinct seasonal variations, with strong transport in spring and winter, and weaker transport in summer and autumn. The variation of net submesoscale vertical heat flux in the upper ocean is consistent with the trend of mixed layer depth, which shows overall upward submesoscale heat transport above the mixed layer and strong alternating positive and negative submesoscale vertical heat transport below the mixed layer, resulting in relatively small net submesoscale vertical heat transport. Coherent spectral analysis of vertical heat flux wavenumber-frequency suggests that submesoscale vertical heat transport below the mixed layer may be caused by linear internal waves, but the upward and downward vertical heat transports induced by linear internal waves counteract each other, leading to a reduced net vertical heat transport after averaging over the season.
Submesoscale processes associated with strong vertical velocities play significant roles in the vertical transport of tracers between the ocean surface and the interior, including heat, buoyancy, and mass. Based on the results of the (1/48)° LLC4320 model, this study investigates the seasonal variations of submesoscale vertical heat transport in the Kuroshio Extension. The results show that submesoscale vertical heat transport in the Kuroshio Extension exhibits distinct seasonal variations, with strong transport in spring and winter, and weaker transport in summer and autumn. The variation of net submesoscale vertical heat flux in the upper ocean is consistent with the trend of mixed layer depth, which shows overall upward submesoscale heat transport above the mixed layer and strong alternating positive and negative submesoscale vertical heat transport below the mixed layer, resulting in relatively small net submesoscale vertical heat transport. Coherent spectral analysis of vertical heat flux wavenumber-frequency suggests that submesoscale vertical heat transport below the mixed layer may be caused by linear internal waves, but the upward and downward vertical heat transports induced by linear internal waves counteract each other, leading to a reduced net vertical heat transport after averaging over the season.
2024, 46(4): 34-46.
doi: 10.12284/hyxb2024027
Abstract:
This study focuses on the physical process of a sea fog event during Typhoon “Lekima” (1909) in the northern Yellow Sea by using observation data, reanalysis data and backward trajectory model. The analysis indicates that the typhoon circulation was the decisive factor determining whether fog formed offshore and developed inland. The warm and humid southerlies from the South Yellow Sea condensed into fog on the colder sea surface besides the typhoon center, which not only provided sufficient moisture for the formation and development of the sea fog but also formed a significant inversion layer over the fog area with the downdraft in the center of the typhoon. The “stable up and turbulent down” structure in the atmospheric boundary layer improved the development of sea fog on the coast and inland area. However, the horizontal wind steering and the strengthening wind speed behind the typhoon strengthened the wind shear in the atmospheric boundary layer, resulting in the enhanced turbulent mixing and the decrease of the stability in the bottom atmospheric boundary layer, which was the main cause of the fog dissipation.
This study focuses on the physical process of a sea fog event during Typhoon “Lekima” (1909) in the northern Yellow Sea by using observation data, reanalysis data and backward trajectory model. The analysis indicates that the typhoon circulation was the decisive factor determining whether fog formed offshore and developed inland. The warm and humid southerlies from the South Yellow Sea condensed into fog on the colder sea surface besides the typhoon center, which not only provided sufficient moisture for the formation and development of the sea fog but also formed a significant inversion layer over the fog area with the downdraft in the center of the typhoon. The “stable up and turbulent down” structure in the atmospheric boundary layer improved the development of sea fog on the coast and inland area. However, the horizontal wind steering and the strengthening wind speed behind the typhoon strengthened the wind shear in the atmospheric boundary layer, resulting in the enhanced turbulent mixing and the decrease of the stability in the bottom atmospheric boundary layer, which was the main cause of the fog dissipation.
2024, 46(4): 47-64.
doi: 10.12284/hyxb2024043
Abstract:
Near-inertial motion is a type of motion in the ocean that is ubiquitous and has a frequency close to the local inertial frequency. Tropical cyclones are one of the mainmechanisms that generate near-inertial motion. This study established a three-dimensional hydrodynamic model based on COAWST (Coupled Ocean-Atmosphere-Wave-Sediment Transport) numerical model system, which couples waves and currents, covers the northern shelf of the South China Sea, and was fully verified. The model was used to simulate the near-inertial motion triggered by Typhoon “Cempaka”, the No.7 typhoon of 2021, on the shelf of western Guangdong. The results indicate that there are spatially two peaks of near-inertial kinetic energy, one in the coastal area with the highest typhoon wind speed, and the other at 130 km offshore, with the second energy peak lasting longer. In the coastal area with water depth shallower than 40 m, the near-inertial motion is mainly in a barotropic mode. As the water depth gradually increases offshore, we found that the near-inertial motions exhibit a clear two-layer structure inthe regions with depths ranging from 70−100 m, with opposite directions of near-inertial flow in the surface and bottom layers, and two energy peaks in the vertical direction, showing the characteristics of the first baroclinic mode. Through dynamic modedecomposition, we found that some areas with obvious two-layer structures are composed of the first and secondbaroclinic modes. As the water depth continues to increase, higher modes of near-inertial flow account for an increasing proportion of the total near-inertial kinetic energy. Momentum balance analysis shows that in the coastal area with shallow water depth and high wind speed, the balance of momentum equation in the entire water layer is dominated by the vertical turbulent viscous force and pressure gradient force. In offshore areas with deeper water depths and lower wind speeds, vertical turbulent viscous forces are concentrated in the surface and bottom layers, and the balance of momentum equation in the intermediate water body is mainly dominated by the pressure gradient forces, Coriolis forces, and local acceleration. This indicates that the near-inertialmotion in the coastal area is mainly driven by barotropicwave caused bywind stress, while in the continental shelf area, the near-inertial motion in the uppermixed layer is driven by wind stress, and the near-inertial motion below the mixed layeris driven by barotropic pressure gradient force.
Near-inertial motion is a type of motion in the ocean that is ubiquitous and has a frequency close to the local inertial frequency. Tropical cyclones are one of the mainmechanisms that generate near-inertial motion. This study established a three-dimensional hydrodynamic model based on COAWST (Coupled Ocean-Atmosphere-Wave-Sediment Transport) numerical model system, which couples waves and currents, covers the northern shelf of the South China Sea, and was fully verified. The model was used to simulate the near-inertial motion triggered by Typhoon “Cempaka”, the No.7 typhoon of 2021, on the shelf of western Guangdong. The results indicate that there are spatially two peaks of near-inertial kinetic energy, one in the coastal area with the highest typhoon wind speed, and the other at 130 km offshore, with the second energy peak lasting longer. In the coastal area with water depth shallower than 40 m, the near-inertial motion is mainly in a barotropic mode. As the water depth gradually increases offshore, we found that the near-inertial motions exhibit a clear two-layer structure inthe regions with depths ranging from 70−100 m, with opposite directions of near-inertial flow in the surface and bottom layers, and two energy peaks in the vertical direction, showing the characteristics of the first baroclinic mode. Through dynamic modedecomposition, we found that some areas with obvious two-layer structures are composed of the first and secondbaroclinic modes. As the water depth continues to increase, higher modes of near-inertial flow account for an increasing proportion of the total near-inertial kinetic energy. Momentum balance analysis shows that in the coastal area with shallow water depth and high wind speed, the balance of momentum equation in the entire water layer is dominated by the vertical turbulent viscous force and pressure gradient force. In offshore areas with deeper water depths and lower wind speeds, vertical turbulent viscous forces are concentrated in the surface and bottom layers, and the balance of momentum equation in the intermediate water body is mainly dominated by the pressure gradient forces, Coriolis forces, and local acceleration. This indicates that the near-inertialmotion in the coastal area is mainly driven by barotropicwave caused bywind stress, while in the continental shelf area, the near-inertial motion in the uppermixed layer is driven by wind stress, and the near-inertial motion below the mixed layeris driven by barotropic pressure gradient force.
2024, 46(4): 65-78.
doi: 10.12284/hyxb2024023
Abstract:
The annual, seasonal, monthly and diurnal variations of sea surface wind field over the Taiwan Strait were analyzed based on the new version of Cross-Calibrated Multi-Platform Version 3.1 (CCMP V3.1) wind data from 1993 to 2022. The results showed that the wind field in the Taiwan Strait and the water around Taiwan Island had obvious spatial distribution characteristics, the topographic effect leads to the maximum and minimum wind speed regions in different sea areas. Because the central Taiwan Strait was affected by the “narrow tube effect”, the wind speed was the highest and the wind direction was basically parallel to the strait in winter; the wind speed in summer was lower than the speed outside the channel, and there was no “narrow tube effect”. In addition, the sea surface wind field also had obvious seasonal and monthly variation characteristics. The northeast wind prevailed in winter, and in this season the wind speed was the highest in the whole year; the southwest wind prevailed in summer with the lowest wind speed; the characteristics of spring and autumn monsoon fields were similar, both prevailing northeast wind; winter monsoon last longer than summer monsoon, accounting for about three quarters of the year. The analysis of the inter-annual variation of wind field showed that the wind direction tended to deflect at a large angle in summer. The annual mean wind speed maintained a basically flat linear trend, and the abnormal high or low in some years was related to the occurrence of El Niño-Southern Oscillation (ENSO). When the diurnal variation characteristics were studied, it was found that the wind speed and direction fluctuated most at 20 PM. The wind speed varied periodically within a day. The diurnal variation of wind direction deflection was most obvious in summer.
The annual, seasonal, monthly and diurnal variations of sea surface wind field over the Taiwan Strait were analyzed based on the new version of Cross-Calibrated Multi-Platform Version 3.1 (CCMP V3.1) wind data from 1993 to 2022. The results showed that the wind field in the Taiwan Strait and the water around Taiwan Island had obvious spatial distribution characteristics, the topographic effect leads to the maximum and minimum wind speed regions in different sea areas. Because the central Taiwan Strait was affected by the “narrow tube effect”, the wind speed was the highest and the wind direction was basically parallel to the strait in winter; the wind speed in summer was lower than the speed outside the channel, and there was no “narrow tube effect”. In addition, the sea surface wind field also had obvious seasonal and monthly variation characteristics. The northeast wind prevailed in winter, and in this season the wind speed was the highest in the whole year; the southwest wind prevailed in summer with the lowest wind speed; the characteristics of spring and autumn monsoon fields were similar, both prevailing northeast wind; winter monsoon last longer than summer monsoon, accounting for about three quarters of the year. The analysis of the inter-annual variation of wind field showed that the wind direction tended to deflect at a large angle in summer. The annual mean wind speed maintained a basically flat linear trend, and the abnormal high or low in some years was related to the occurrence of El Niño-Southern Oscillation (ENSO). When the diurnal variation characteristics were studied, it was found that the wind speed and direction fluctuated most at 20 PM. The wind speed varied periodically within a day. The diurnal variation of wind direction deflection was most obvious in summer.
2024, 46(4): 79-89.
doi: 10.12284/hyxb2024045
Abstract:
The impact of the El Niño-Southern Oscillation (ENSO) on the climate of the low-latitude tropical region of the Malay Peninsula, particularly with regard to precipitation, remains a topic of debate. This study focuses on the NTT-3 drill core from Setiu Lagoon in Terengganu, northeastern Malay Peninsula. By employing analyses such as grain size, total organic carbon/nitrogen content, C/N ratio, and XRF core scanning, this research investigates the sedimentary environmental changes in the drill core and their response to ENSO. The results reveal two distinct trends in the drill core record, appearing around 1970 (at 84 cm depth). Sediment characteristics such as grain size and geochemical features of both organic and inorganic components suggest the possible occurrence of episodic sedimentation or sedimentary interruptions, with exceptionally slow sedimentation rates observed in the lower part of the core before 1970. Since 1970, the organic components in the lagoon sediment primarily originate from mangroves, accompanied by contributions from freshwater phytoplankton associated with river inputs. Spectral analysis indicates a pronounced ENSO periodic variation in the upper part of the drill core since 1970. The variations in Zr/Rb and Zr/Ti ratios correlate well with the occurrences of strong El Niño and La Niña events. This conclusion not only supports contemporary observations of climate change in the eastern coastal region of the Malay Peninsula but also provides direct geological evidence of ENSO variations in the sedimentary record. This discovery holds significant practical implications for a comprehensive understanding of the impact of ENSO on climate change in Asia, regional land-sea interaction processes, and environmental responses.
The impact of the El Niño-Southern Oscillation (ENSO) on the climate of the low-latitude tropical region of the Malay Peninsula, particularly with regard to precipitation, remains a topic of debate. This study focuses on the NTT-3 drill core from Setiu Lagoon in Terengganu, northeastern Malay Peninsula. By employing analyses such as grain size, total organic carbon/nitrogen content, C/N ratio, and XRF core scanning, this research investigates the sedimentary environmental changes in the drill core and their response to ENSO. The results reveal two distinct trends in the drill core record, appearing around 1970 (at 84 cm depth). Sediment characteristics such as grain size and geochemical features of both organic and inorganic components suggest the possible occurrence of episodic sedimentation or sedimentary interruptions, with exceptionally slow sedimentation rates observed in the lower part of the core before 1970. Since 1970, the organic components in the lagoon sediment primarily originate from mangroves, accompanied by contributions from freshwater phytoplankton associated with river inputs. Spectral analysis indicates a pronounced ENSO periodic variation in the upper part of the drill core since 1970. The variations in Zr/Rb and Zr/Ti ratios correlate well with the occurrences of strong El Niño and La Niña events. This conclusion not only supports contemporary observations of climate change in the eastern coastal region of the Malay Peninsula but also provides direct geological evidence of ENSO variations in the sedimentary record. This discovery holds significant practical implications for a comprehensive understanding of the impact of ENSO on climate change in Asia, regional land-sea interaction processes, and environmental responses.
2024, 46(4): 90-105.
doi: 10.12284/hyxb2024041
Abstract:
Taiwan Strait is the largest strait in China and the main channel for material and energy exchange between the East China Sea and the South China Sea. The topography changes dramatically and the tidal environment is complex in the Strait. In addition, many mountainous streams on both sides carry a large amount of sediment into the strait. It is an ideal place to study dynamic sedimentation processes. Currently, due to a lack of high-resolution bathymetry and relevant data for the entire Taiwan Strait, there are few studies on modeling the tide and sediment behaviors of the Taiwan Strait as a whole. In this study, based on high-resolution bathymetric and relevant hydrological data, a two-dimensional tidal current numerical model of the Taiwan Strait has been established, and a sediment transport module has been coupled to simulate the sediment transport in the Taiwan Strait. The dynamic simulation results indicate that the tidal current field in the Taiwan Strait is governed by two tidal waves from the south and north, exhibiting distinct temporal and spatial characteristics. The tidal flow velocity is higher in summer than in winter, and it is lower in the central part of the strait compared to the southern and northern sides, with the northern side being less than the southern side. Based on the deposition and erosion simulation results, the Taiwan Strait is categorized into three main types and a total of seven sedimentary subdivisions: deposition zones, erosion zones, and deposition-erosion equilibrium zones. The maximum sedimentation rate in the accumulation zones can reach 5 cm/a, primarily concentrated in the northern part of the Taiwan Bank, with erosion rates ranging from 2 cm/a to 5 cm/a in the erosion zones. Leveraging these simulation outcomes, this study constructs a sediment transport model and a ‘source-to-sink’ pattern model for the Taiwan Strait, elucidating the dynamic mechanisms behind the strait’s deposition and erosion changes and the ‘source-to-sink’ process.
Taiwan Strait is the largest strait in China and the main channel for material and energy exchange between the East China Sea and the South China Sea. The topography changes dramatically and the tidal environment is complex in the Strait. In addition, many mountainous streams on both sides carry a large amount of sediment into the strait. It is an ideal place to study dynamic sedimentation processes. Currently, due to a lack of high-resolution bathymetry and relevant data for the entire Taiwan Strait, there are few studies on modeling the tide and sediment behaviors of the Taiwan Strait as a whole. In this study, based on high-resolution bathymetric and relevant hydrological data, a two-dimensional tidal current numerical model of the Taiwan Strait has been established, and a sediment transport module has been coupled to simulate the sediment transport in the Taiwan Strait. The dynamic simulation results indicate that the tidal current field in the Taiwan Strait is governed by two tidal waves from the south and north, exhibiting distinct temporal and spatial characteristics. The tidal flow velocity is higher in summer than in winter, and it is lower in the central part of the strait compared to the southern and northern sides, with the northern side being less than the southern side. Based on the deposition and erosion simulation results, the Taiwan Strait is categorized into three main types and a total of seven sedimentary subdivisions: deposition zones, erosion zones, and deposition-erosion equilibrium zones. The maximum sedimentation rate in the accumulation zones can reach 5 cm/a, primarily concentrated in the northern part of the Taiwan Bank, with erosion rates ranging from 2 cm/a to 5 cm/a in the erosion zones. Leveraging these simulation outcomes, this study constructs a sediment transport model and a ‘source-to-sink’ pattern model for the Taiwan Strait, elucidating the dynamic mechanisms behind the strait’s deposition and erosion changes and the ‘source-to-sink’ process.
2024, 46(4): 106-121.
doi: 10.12284/hyxb2024029
Abstract:
The Japan Sea is the largest marginal sea in the northwestern Pacific Ocean. For a long time, it has been widely believed that the sediments are deposited in strongly reducing environment, which results in extremely weak magnetic signals and then restricts the application of frequently-used magnetic method in this region. To investigate deeply the availability of magnetic indicators in paleoenvironmental and paleoceanographic studiesin the Japan Sea, we conducted systematic rock magnetic analyses, high-resolution accelerator mass spectrometer (AMS) 14C dating, and grain-size analysis on a 626-cm-long sediment core (LV87-2-3, water depth 740 m) recovered from the northern Japan Sea that has been studied in relatively low level. The results indicate that the studied core corresponds to a sedimentary record since approximately 48.3 ka BP. The majority of primary ferrimagnetic minerals, mainly magnetite, in the sediments below 55 cm, had been reduced into pyrite, which caused weakly magnetic intensity. This is associated closely with the intensified stratification of water body and the increase in surface productivity during interstadials in the Dansgaard-Oeschger (D-O) cycles. Nevertheless, there are still four strong magneticlayers characterized by elevated percentages of high-coercivity minerals (i.e., hematite and goethite), which are termed as ‘hard-magnetic abnormal’ layers and correspond well with the Heinrich Events. This indicatesrelatively weak reducing conditions that were resulted from the enhanced East Asian Winter Monsoon (EAWM) and injection of high salinity Tsushima Warm Current (TWC). These changes, however, are not reflected by the grain-size of sediment. Our study therefore not only indicates that the role of magnetic parameters in the paleoenvironmental and palaeoceanographic reconstructions of the Japan Sea during the last glacial, but also provides new perspectives and ideasfor relevant investigations in the future.
The Japan Sea is the largest marginal sea in the northwestern Pacific Ocean. For a long time, it has been widely believed that the sediments are deposited in strongly reducing environment, which results in extremely weak magnetic signals and then restricts the application of frequently-used magnetic method in this region. To investigate deeply the availability of magnetic indicators in paleoenvironmental and paleoceanographic studiesin the Japan Sea, we conducted systematic rock magnetic analyses, high-resolution accelerator mass spectrometer (AMS) 14C dating, and grain-size analysis on a 626-cm-long sediment core (LV87-2-3, water depth 740 m) recovered from the northern Japan Sea that has been studied in relatively low level. The results indicate that the studied core corresponds to a sedimentary record since approximately 48.3 ka BP. The majority of primary ferrimagnetic minerals, mainly magnetite, in the sediments below 55 cm, had been reduced into pyrite, which caused weakly magnetic intensity. This is associated closely with the intensified stratification of water body and the increase in surface productivity during interstadials in the Dansgaard-Oeschger (D-O) cycles. Nevertheless, there are still four strong magneticlayers characterized by elevated percentages of high-coercivity minerals (i.e., hematite and goethite), which are termed as ‘hard-magnetic abnormal’ layers and correspond well with the Heinrich Events. This indicatesrelatively weak reducing conditions that were resulted from the enhanced East Asian Winter Monsoon (EAWM) and injection of high salinity Tsushima Warm Current (TWC). These changes, however, are not reflected by the grain-size of sediment. Our study therefore not only indicates that the role of magnetic parameters in the paleoenvironmental and palaeoceanographic reconstructions of the Japan Sea during the last glacial, but also provides new perspectives and ideasfor relevant investigations in the future.
2024, 46(4): 122-132.
doi: 10.12284/hyxb2024035
Abstract:
The double-row perforated cylinder breakwater is a new type of environment-friendly breakwater, and the research on its wave absorbing characteristics is of great engineering significance. With the development of artificial intelligence, solving the water dynamics problem of breakwater based on machine learning technology has become a new research paradigm. This paper proposes a Convolutional Neural Network (CNN) model based on Sparrow Search Algorithm (SSA) to achieve intelligent optimization prediction of transmission coefficient of double-row perforated cylindrical breakwater. The results show that: (1) wave height, wave period, wavelength, wave velocity, row spacing, hole rate and water depth are identified as the key factors affecting the transmission coefficient. (2) When the population size of the SSA-CNN model is 10, the R2 value of the wave transmission coefficient prediction reaches 0.9909, and the average relative error is reduced by 22.24% compared with the single CNN model. The research results provide a new optimal prediction model for the study of wave transmission by using neural networks.
The double-row perforated cylinder breakwater is a new type of environment-friendly breakwater, and the research on its wave absorbing characteristics is of great engineering significance. With the development of artificial intelligence, solving the water dynamics problem of breakwater based on machine learning technology has become a new research paradigm. This paper proposes a Convolutional Neural Network (CNN) model based on Sparrow Search Algorithm (SSA) to achieve intelligent optimization prediction of transmission coefficient of double-row perforated cylindrical breakwater. The results show that: (1) wave height, wave period, wavelength, wave velocity, row spacing, hole rate and water depth are identified as the key factors affecting the transmission coefficient. (2) When the population size of the SSA-CNN model is 10, the R2 value of the wave transmission coefficient prediction reaches 0.9909, and the average relative error is reduced by 22.24% compared with the single CNN model. The research results provide a new optimal prediction model for the study of wave transmission by using neural networks.
2024, 46(4): 133-142.
doi: 10.12284/hyxb2024039
Abstract:
Sea surface gusts are important marine dynamic environmental information required for the development of marine resources, marine disaster prevention and reduction, and marine scientific research. However, so far, there has been a serious lack of observational data on sea surface gusts, which has hindered the development of gust forecasting, application research, and other aspects. This article uses the backscatter coefficients in the C and Ku bands of the dual frequency HY-2B satellite altimeter to correct the existing sea surface wind speed (\begin{document}$ {U}_{10} $\end{document} ![]()
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Sea surface gusts are important marine dynamic environmental information required for the development of marine resources, marine disaster prevention and reduction, and marine scientific research. However, so far, there has been a serious lack of observational data on sea surface gusts, which has hindered the development of gust forecasting, application research, and other aspects. This article uses the backscatter coefficients in the C and Ku bands of the dual frequency HY-2B satellite altimeter to correct the existing sea surface wind speed (
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