Identification of ocean eddies from a large amount of ocean data provided by satellite measurements and numerical simulations is crucial,while the academia has invented many traditional physical methods with accurate ...Identification of ocean eddies from a large amount of ocean data provided by satellite measurements and numerical simulations is crucial,while the academia has invented many traditional physical methods with accurate detection capability,but their detection computational efficiency is low.In recent years,with the increasing application of deep learning in ocean feature detection,many deep learning-based eddy detection models have been developed for more effective eddy detection from ocean data.But it is difficult for them to precisely fit some physical features implicit in traditional methods,leading to inaccurate identification of ocean eddies.In this study,to address the low efficiency of traditional physical methods and the low detection accuracy of deep learning models,we propose a solution that combines the target detection model Faster Region with CNN feature(Faster R-CNN)with the traditional dynamic algorithm Angular Momentum Eddy Detection and Tracking Algorithm(AMEDA).We use Faster R-CNN to detect and generate bounding boxes for eddies,allowing AMEDA to detect the eddy center within these bounding boxes,thus reducing the complexity of center detection.To demonstrate the detection efficiency and accuracy of this model,this paper compares the experimental results with AMEDA and the deep learning-based eddy detection method eddyNet.The results show that the eddy detection results of this paper are more accurate than eddyNet and have higher execution efficiency than AMEDA.展开更多
This study focuses on the spatial and temporal distribution characteristics of mesoscale eddies in the South China Sea(SCS). An automatic eddy detection method,based on the geometry of velocity vectors,was adopted to ...This study focuses on the spatial and temporal distribution characteristics of mesoscale eddies in the South China Sea(SCS). An automatic eddy detection method,based on the geometry of velocity vectors,was adopted to obtain an eddy dataset from 21 years of satellite altimeter data. Analysis revealed that the number of anticyclonic eddies was nearly equal to cyclonic eddies; in the SCS,cyclonic eddies are generally stronger than anticyclonic eddies and anticyclonic eddies are larger and longer-lived than cyclonic eddies. Anticyclonic eddies tend to survive longer in the spring and summer,while cyclonic eddies have longer lifetimes in the autumn and winter. The characteristics and seasonal variations of eddies in the SCS are strongly related to variations in general ocean circulation,in the homogeneity of surface wind stress,and in the unevenness of bottom topography in the SCS. The spatial and temporal variation of mesoscale eddies in the SCS could,therefore,be an important index for understanding local hydrodynamics and regional climate change.展开更多
Smaller mesoscale eddies(SMEs)have an important effect on the transmission of ocean temperatures,salinity,energy,and marine biochemical processes.However,traditional altimeters,the dominant sensors used to identify an...Smaller mesoscale eddies(SMEs)have an important effect on the transmission of ocean temperatures,salinity,energy,and marine biochemical processes.However,traditional altimeters,the dominant sensors used to identify and track eddies,have made it challenging to observe SMEs accurately due to resolution limitations.Eddies drive local upwelling or downwelling,leaving signatures on sea surface temperatures(SSTs)and chlorophyll concentrations(Chls).SST can be observed by spaceborne infrared sensors,and Chl can be measured by ocean color remote sensing.Therefore,multisatellite observations provide an opportunity to obtain information to characterize SMEs.In this paper,an eddy detection algorithm based on SST and Chl images is proposed,which identifies eddies by characterizing the spatial and temporal distribution of SST and Chl data.The algorithm is applied to characterize and analyze SMEs in the Kuroshio Extension.Statistical results on their distribution and seasonal variability are shown,and the formation processes are preliminarily discussed.SMEs generation may be contributed by horizontal strain instability,the interaction of topographic obstacles and currents,and wind stress curl.展开更多
Purpose–The purpose of this study is to study the quantitative evaluation method of contact wire cracks by analyzing the changing law of eddy current signal characteristics under different cracks of contact wire of h...Purpose–The purpose of this study is to study the quantitative evaluation method of contact wire cracks by analyzing the changing law of eddy current signal characteristics under different cracks of contact wire of high-speed railway so as to provide a new way of thinking and method for the detection of contact wire injuries of high-speed railway.Design/methodology/approach–Based on the principle of eddy current detection and the specification parameters of high-speed railway contact wires in China,a finite element model for eddy current testing of contact wires was established to explore the variation patterns of crack signal characteristics in numerical simulation.A crack detection system based on eddy current detection was built,and eddy current detection voltage data was obtained for cracks of different depths and widths.By analyzing the variation law of eddy current signals,characteristic parameters were obtained and a quantitative evaluation model for crack width and depth was established based on the back propagation(BP)neural network.Findings–Numerical simulation and experimental detection of eddy current signal change rule is basically consistent,based on the law of the selected characteristics of the parameters in the BP neural network crack quantitative evaluation model also has a certain degree of effectiveness and reliability.BP neural network training results show that the classification accuracy for different widths and depths of the classification is 100 and 85.71%,respectively,and can be effectively realized on the high-speed railway contact line cracks of the quantitative evaluation classification.Originality/value–This study establishes a new type of high-speed railway contact wire crack detection and identification method,which provides a new technical means for high-speed railway contact wire injury detection.The study of eddy current characteristic law and quantitative evaluation model for different cracks in contact line has important academic value and practical significance,and it has certain guiding significance for the detection technology of contact line in high-speed railway.展开更多
Oceanic mesoscale eddies typically span tens to hundreds of kilometers and last several weeks to months.They are a key dynamic process influencing the distribution of oceanic energy,affecting energy budgets,heat distr...Oceanic mesoscale eddies typically span tens to hundreds of kilometers and last several weeks to months.They are a key dynamic process influencing the distribution of oceanic energy,affecting energy budgets,heat distributions,and material transport.Advances in satellite remote sensing and in situ observation over the past half-century have substantially enhanced our understanding of the statistical properties,energetics,and dynamic mechanisms of mesoscale eddies,establishing this field as a major focus in physical oceanography.This article presents a comprehensive review of recent advancements in 6 key areas of mesoscale eddy research:(a)eddy detection methods and data products(leading automated detection methods and the corresponding eddy datasets and data products currently available),(b)eddy generation and dissipation(eddy generation,development,and dissipation mechanisms),(c)energy cascades(energy cascades between eddies,large-scale circulation and submesoscale processes,the role of these processes in modulating the energy transfer of near-inertial internal and surface waves,and research progress in related parameterization),(d)air-sea interaction(eddy-induced interactions,especially the interaction between eddies and typhoons),(e)interdisciplinary studies(impacts of eddies on biogeochemistry,acoustics,and other related fields),and(f)observation studies(programs dedicated to studying mesoscale eddies through in situ observation).This article also discusses research prospects on mesoscale eddies.展开更多
基金the National Science Foundation of China(No.42175194)the National Natural Science Foundation of China(No.41976165)for funding this work.
文摘Identification of ocean eddies from a large amount of ocean data provided by satellite measurements and numerical simulations is crucial,while the academia has invented many traditional physical methods with accurate detection capability,but their detection computational efficiency is low.In recent years,with the increasing application of deep learning in ocean feature detection,many deep learning-based eddy detection models have been developed for more effective eddy detection from ocean data.But it is difficult for them to precisely fit some physical features implicit in traditional methods,leading to inaccurate identification of ocean eddies.In this study,to address the low efficiency of traditional physical methods and the low detection accuracy of deep learning models,we propose a solution that combines the target detection model Faster Region with CNN feature(Faster R-CNN)with the traditional dynamic algorithm Angular Momentum Eddy Detection and Tracking Algorithm(AMEDA).We use Faster R-CNN to detect and generate bounding boxes for eddies,allowing AMEDA to detect the eddy center within these bounding boxes,thus reducing the complexity of center detection.To demonstrate the detection efficiency and accuracy of this model,this paper compares the experimental results with AMEDA and the deep learning-based eddy detection method eddyNet.The results show that the eddy detection results of this paper are more accurate than eddyNet and have higher execution efficiency than AMEDA.
基金Supported by the National High Technology Research and Development Program of China(863 Program)(No.2013AA09A505)the National Natural Science Foundation of China(No.U1133001)the NSFC-Shandong Joint Fund for Marine Science Research Centers Grant(No.U1406401)
文摘This study focuses on the spatial and temporal distribution characteristics of mesoscale eddies in the South China Sea(SCS). An automatic eddy detection method,based on the geometry of velocity vectors,was adopted to obtain an eddy dataset from 21 years of satellite altimeter data. Analysis revealed that the number of anticyclonic eddies was nearly equal to cyclonic eddies; in the SCS,cyclonic eddies are generally stronger than anticyclonic eddies and anticyclonic eddies are larger and longer-lived than cyclonic eddies. Anticyclonic eddies tend to survive longer in the spring and summer,while cyclonic eddies have longer lifetimes in the autumn and winter. The characteristics and seasonal variations of eddies in the SCS are strongly related to variations in general ocean circulation,in the homogeneity of surface wind stress,and in the unevenness of bottom topography in the SCS. The spatial and temporal variation of mesoscale eddies in the SCS could,therefore,be an important index for understanding local hydrodynamics and regional climate change.
基金The Marine S&T Fund of Shandong Province for Pilot National Laboratory for Marine Science and Technology(Qingdao)under contract Nos 2022QNLM050301-4 and 2021WHZZB1705the National Natural Science Foundation of China under contract Nos 41527901 and 42030406the National Key R&D Program of China under contract No.2019YFD0901001。
文摘Smaller mesoscale eddies(SMEs)have an important effect on the transmission of ocean temperatures,salinity,energy,and marine biochemical processes.However,traditional altimeters,the dominant sensors used to identify and track eddies,have made it challenging to observe SMEs accurately due to resolution limitations.Eddies drive local upwelling or downwelling,leaving signatures on sea surface temperatures(SSTs)and chlorophyll concentrations(Chls).SST can be observed by spaceborne infrared sensors,and Chl can be measured by ocean color remote sensing.Therefore,multisatellite observations provide an opportunity to obtain information to characterize SMEs.In this paper,an eddy detection algorithm based on SST and Chl images is proposed,which identifies eddies by characterizing the spatial and temporal distribution of SST and Chl data.The algorithm is applied to characterize and analyze SMEs in the Kuroshio Extension.Statistical results on their distribution and seasonal variability are shown,and the formation processes are preliminarily discussed.SMEs generation may be contributed by horizontal strain instability,the interaction of topographic obstacles and currents,and wind stress curl.
文摘Purpose–The purpose of this study is to study the quantitative evaluation method of contact wire cracks by analyzing the changing law of eddy current signal characteristics under different cracks of contact wire of high-speed railway so as to provide a new way of thinking and method for the detection of contact wire injuries of high-speed railway.Design/methodology/approach–Based on the principle of eddy current detection and the specification parameters of high-speed railway contact wires in China,a finite element model for eddy current testing of contact wires was established to explore the variation patterns of crack signal characteristics in numerical simulation.A crack detection system based on eddy current detection was built,and eddy current detection voltage data was obtained for cracks of different depths and widths.By analyzing the variation law of eddy current signals,characteristic parameters were obtained and a quantitative evaluation model for crack width and depth was established based on the back propagation(BP)neural network.Findings–Numerical simulation and experimental detection of eddy current signal change rule is basically consistent,based on the law of the selected characteristics of the parameters in the BP neural network crack quantitative evaluation model also has a certain degree of effectiveness and reliability.BP neural network training results show that the classification accuracy for different widths and depths of the classification is 100 and 85.71%,respectively,and can be effectively realized on the high-speed railway contact line cracks of the quantitative evaluation classification.Originality/value–This study establishes a new type of high-speed railway contact wire crack detection and identification method,which provides a new technical means for high-speed railway contact wire injury detection.The study of eddy current characteristic law and quantitative evaluation model for different cracks in contact line has important academic value and practical significance,and it has certain guiding significance for the detection technology of contact line in high-speed railway.
基金This research was supported by the National Natural Science Foundation of China under contract nos.42250710152,42192562,and 41906008the Southern Marine Science and Engineering Guangdong Laboratory(Zhuhai)-funded project under contract SML2020SP007.
文摘Oceanic mesoscale eddies typically span tens to hundreds of kilometers and last several weeks to months.They are a key dynamic process influencing the distribution of oceanic energy,affecting energy budgets,heat distributions,and material transport.Advances in satellite remote sensing and in situ observation over the past half-century have substantially enhanced our understanding of the statistical properties,energetics,and dynamic mechanisms of mesoscale eddies,establishing this field as a major focus in physical oceanography.This article presents a comprehensive review of recent advancements in 6 key areas of mesoscale eddy research:(a)eddy detection methods and data products(leading automated detection methods and the corresponding eddy datasets and data products currently available),(b)eddy generation and dissipation(eddy generation,development,and dissipation mechanisms),(c)energy cascades(energy cascades between eddies,large-scale circulation and submesoscale processes,the role of these processes in modulating the energy transfer of near-inertial internal and surface waves,and research progress in related parameterization),(d)air-sea interaction(eddy-induced interactions,especially the interaction between eddies and typhoons),(e)interdisciplinary studies(impacts of eddies on biogeochemistry,acoustics,and other related fields),and(f)observation studies(programs dedicated to studying mesoscale eddies through in situ observation).This article also discusses research prospects on mesoscale eddies.
