Wave climate analysis and other applications for the Pacific Ocean require a reliable wave hindcast. Five source and sink term packages in the Wavewatch III model （v3.14 and v4.18） are compared and assessed in this ...Wave climate analysis and other applications for the Pacific Ocean require a reliable wave hindcast. Five source and sink term packages in the Wavewatch III model （v3.14 and v4.18） are compared and assessed in this study through comprehensive observations, including altimeter significant wave height, advanced synthetic aperture radar swell, and buoy wave parameters and spectrum. In addition to the evaluation of typically used integral parameters, the spectra partitioning method contributes to the detailed wave system and wave maturity validation. The modified performance evaluation method （PS） effectively reduces attribute numbers and facilitates the overall assessment. To avoid possible misleading results in the root mean square error-based validations, another indicator called HH （indicating the two authors） is also calculated to guarantee the consistency of the results. The widely used Tolman and Chalikov （TC） package is still generally efficient in determining the integral properties of wave spectra but is physically deficient in explaining the dissipation processes. The ST4 package performs well in overall wave parameters and significantly improves the accuracy of wave systems in the open ocean. Meanwhile, the newly published ST6 package is slightly better in determining swell energy variations. The two packages （ACC350 and BIA） obtained from Wavewatch III v3.14 exhibit large scatters at different sea states. The three most ideal packages are further examined in terms of reproducing wave- induced momentum flux from the perspective of transport. Stokes transport analysis indicates that ST4 is the closest to the NDBC-buoy-spectrum-based transport values, and TC and ST6 tend to overestimate and underestimate the transport magnitude, respectively, in swell mixed areas. This difference must be considered, particularly in air-wave-current coupling research and upper ocean analysis. The assessment results provide guidance for the selection of ST4 for use in a background Pacific Ocean hindcast fo展开更多
A method of source depth estimation based on the multi-path time delay difference is proposed. When the minimum time arrivals in all receiver depths are snapped to a certain time on time delay-depth plane, time delay ...A method of source depth estimation based on the multi-path time delay difference is proposed. When the minimum time arrivals in all receiver depths are snapped to a certain time on time delay-depth plane, time delay arrivals of surface-bottom reflection and bottom-surface reflection intersect at the source depth. Two hydrophones deployed vertically with a certain interval are required at least. If the receiver depths are known, the pair of time delays can be used to estimate the source depth. With the proposed method the source depth can be estimated successfully in a moderate range in the deep ocean without complicated matched-field calculations in the simulations and experiments.展开更多
Subsurface eddies(SSEs)are common features of the ocean interior.They are particularly abundant in oceanic basins and the vicinity of major intermediate water outfl ows.They are responsible for subsurface transport of...Subsurface eddies(SSEs)are common features of the ocean interior.They are particularly abundant in oceanic basins and the vicinity of major intermediate water outfl ows.They are responsible for subsurface transport of mass,heat,and salt.Analysis of high-resolution general circulation model data has revealed the existence of subsurface anticyclonic eddies(SSAEs)and subsurface cyclonic eddies(SSCEs)in the northwestern tropical Pacifi c Ocean.SSEs are abundant east of the Philippines(0°–22°N,120°E–140°E)and in latitude bands between 9°N–17°N east of 140°E.The composite structure of SSEs was investigated.SSEs had a core at about 400-m water depth and their maximum meridional velocity exceeded 10 cm/s.They exhibited two cores with diff erent salinity polarities in the surface and subsurface.Additionally,spatial distributions of heat transport induced by SSEs in the northwestern tropical Pacifi c were presented for the fi rst time.A net equatorward heat fl ux toward a temperature up-gradient was observed.The analysis of eddy-mean fl ow interactions revealed that the circulation is baroclinically and barotropically unstable at diff erent depths and to diff ering degrees.The energy conversions suggest that both barotropic and baroclinic instabilities are responsible for SSE generation east of the Philippines,whereas baroclinic instability caused by a horizontal density gradient and vertical eddy heat fl ux are important between 9°N and 17°N east of 140°E.Meridional movement of the north equatorial current and the north equatorial undercurrent can contribute to SSE generation in our study region.展开更多
First-arrival seismic traveltime tomography(FAST)is a well-established technique to estimate subsurface velocity structures.Although several existing open-source packages are available for first-arrival traveltime tom...First-arrival seismic traveltime tomography(FAST)is a well-established technique to estimate subsurface velocity structures.Although several existing open-source packages are available for first-arrival traveltime tomography,most were written in compiled languages and lack sufficient extendibility for new algorithms and functionalities.In this work,we develop an open-source,selfcontained FAST package based on MATLAB,one of the most popular interpreted scientific programming languages,with a focus on ocean bottom seismometer refraction traveltime tomography.Our package contains a complete traveltime tomography workflow,including ray-tracing-based first-arrival traveltime computation,linearized inversion,quality control,and high-quality visualization.We design the package as a modular toolbox,making it convenient to integrate new algorithms and functionalities as needed.At the current stage,our package is most efficient for performing FAST for two-dimensional ocean bottom seismometer surveys.We demonstrate the efficacy and accuracy of our package by using a synthetic data example based on a modified Marmousi model.展开更多
In this paper,we consider the initial-boundary value problem for the large scale three-dimensional(3D)viscous primitive equations under random force.Assuming that the random force and the heat source satisfy the some ...In this paper,we consider the initial-boundary value problem for the large scale three-dimensional(3D)viscous primitive equations under random force.Assuming that the random force and the heat source satisfy the some assumptions,we firstly establish rigorous a priori bounds with coefficients which depend only on boundary data,initial data and the geometry of the problem,and then with the aid of these a priori bounds,the continuous dependence of the solution on changes in the heat source is obtained.展开更多
In this paper we study the problem of generation of surface waves produced due to a） rolling of the plate and b） presence of a line source in front of a fixed vertical plate. The amplitudes of radiated waves at larg...In this paper we study the problem of generation of surface waves produced due to a） rolling of the plate and b） presence of a line source in front of a fixed vertical plate. The amplitudes of radiated waves at large distance from the plate, in both cases, are obtained by a suitable application of Green＇s integral theorem. These are then studied graphically for various values of the ice cover parameter.展开更多
基金The National High Technology Research and Development Program(863 Program) of China under contract No.2013AA122803the Strategic Priority Research Program of the Chinese Academy of Sciences under contract No.XDA11010104
文摘Wave climate analysis and other applications for the Pacific Ocean require a reliable wave hindcast. Five source and sink term packages in the Wavewatch III model （v3.14 and v4.18） are compared and assessed in this study through comprehensive observations, including altimeter significant wave height, advanced synthetic aperture radar swell, and buoy wave parameters and spectrum. In addition to the evaluation of typically used integral parameters, the spectra partitioning method contributes to the detailed wave system and wave maturity validation. The modified performance evaluation method （PS） effectively reduces attribute numbers and facilitates the overall assessment. To avoid possible misleading results in the root mean square error-based validations, another indicator called HH （indicating the two authors） is also calculated to guarantee the consistency of the results. The widely used Tolman and Chalikov （TC） package is still generally efficient in determining the integral properties of wave spectra but is physically deficient in explaining the dissipation processes. The ST4 package performs well in overall wave parameters and significantly improves the accuracy of wave systems in the open ocean. Meanwhile, the newly published ST6 package is slightly better in determining swell energy variations. The two packages （ACC350 and BIA） obtained from Wavewatch III v3.14 exhibit large scatters at different sea states. The three most ideal packages are further examined in terms of reproducing wave- induced momentum flux from the perspective of transport. Stokes transport analysis indicates that ST4 is the closest to the NDBC-buoy-spectrum-based transport values, and TC and ST6 tend to overestimate and underestimate the transport magnitude, respectively, in swell mixed areas. This difference must be considered, particularly in air-wave-current coupling research and upper ocean analysis. The assessment results provide guidance for the selection of ST4 for use in a background Pacific Ocean hindcast fo
基金Supported by the National Natural Science Foundation of China under Grant No 11174235
文摘A method of source depth estimation based on the multi-path time delay difference is proposed. When the minimum time arrivals in all receiver depths are snapped to a certain time on time delay-depth plane, time delay arrivals of surface-bottom reflection and bottom-surface reflection intersect at the source depth. Two hydrophones deployed vertically with a certain interval are required at least. If the receiver depths are known, the pair of time delays can be used to estimate the source depth. With the proposed method the source depth can be estimated successfully in a moderate range in the deep ocean without complicated matched-field calculations in the simulations and experiments.
基金Supported by the National Key Research and Development Plan(Nos.2016YFC1400505SQ,2017YFSF070166)the National Natural Science Foundation of China(No.41676005)the NSFC Innovative Group(No.41421005),the CAS“Huiquan Scholar”,and the CAS Youth Innovation Promotion Association。
文摘Subsurface eddies(SSEs)are common features of the ocean interior.They are particularly abundant in oceanic basins and the vicinity of major intermediate water outfl ows.They are responsible for subsurface transport of mass,heat,and salt.Analysis of high-resolution general circulation model data has revealed the existence of subsurface anticyclonic eddies(SSAEs)and subsurface cyclonic eddies(SSCEs)in the northwestern tropical Pacifi c Ocean.SSEs are abundant east of the Philippines(0°–22°N,120°E–140°E)and in latitude bands between 9°N–17°N east of 140°E.The composite structure of SSEs was investigated.SSEs had a core at about 400-m water depth and their maximum meridional velocity exceeded 10 cm/s.They exhibited two cores with diff erent salinity polarities in the surface and subsurface.Additionally,spatial distributions of heat transport induced by SSEs in the northwestern tropical Pacifi c were presented for the fi rst time.A net equatorward heat fl ux toward a temperature up-gradient was observed.The analysis of eddy-mean fl ow interactions revealed that the circulation is baroclinically and barotropically unstable at diff erent depths and to diff ering degrees.The energy conversions suggest that both barotropic and baroclinic instabilities are responsible for SSE generation east of the Philippines,whereas baroclinic instability caused by a horizontal density gradient and vertical eddy heat fl ux are important between 9°N and 17°N east of 140°E.Meridional movement of the north equatorial current and the north equatorial undercurrent can contribute to SSE generation in our study region.
基金financially supported by the Key Special Project for Introduced Talents Team of Southern Marine Science and Engineering Guangdong Laboratory (Guangzhou) (Grant No. GML2019 ZD0207)supported by the Guangzhou Municipal Science and Technology Bureau (Grant No. 202102021054)
文摘First-arrival seismic traveltime tomography(FAST)is a well-established technique to estimate subsurface velocity structures.Although several existing open-source packages are available for first-arrival traveltime tomography,most were written in compiled languages and lack sufficient extendibility for new algorithms and functionalities.In this work,we develop an open-source,selfcontained FAST package based on MATLAB,one of the most popular interpreted scientific programming languages,with a focus on ocean bottom seismometer refraction traveltime tomography.Our package contains a complete traveltime tomography workflow,including ray-tracing-based first-arrival traveltime computation,linearized inversion,quality control,and high-quality visualization.We design the package as a modular toolbox,making it convenient to integrate new algorithms and functionalities as needed.At the current stage,our package is most efficient for performing FAST for two-dimensional ocean bottom seismometer surveys.We demonstrate the efficacy and accuracy of our package by using a synthetic data example based on a modified Marmousi model.
基金Supported by Innovation Team Project of Humanities and Social Sciences in Colleges and Universities of Guangdong Province(Grant No.2020wcxtd008)Research Team Project Funding of Guangzhou Huashang college(Grant No.2021HSKT01).
文摘In this paper,we consider the initial-boundary value problem for the large scale three-dimensional(3D)viscous primitive equations under random force.Assuming that the random force and the heat source satisfy the some assumptions,we firstly establish rigorous a priori bounds with coefficients which depend only on boundary data,initial data and the geometry of the problem,and then with the aid of these a priori bounds,the continuous dependence of the solution on changes in the heat source is obtained.
基金Supported by the Department of Science and Technology,Government of India for their financial support of this work through the SERC Fast Track Scheme for Young Scientist(No.SR/FTP/MS-037/2011)
文摘In this paper we study the problem of generation of surface waves produced due to a） rolling of the plate and b） presence of a line source in front of a fixed vertical plate. The amplitudes of radiated waves at large distance from the plate, in both cases, are obtained by a suitable application of Green＇s integral theorem. These are then studied graphically for various values of the ice cover parameter.
