The current lack of high-precision information on subsurface seawater is a constraint in fishery research.Based on Argo temperature and salinity profiles,this study applied the gradient-dependent optimal interpolation...The current lack of high-precision information on subsurface seawater is a constraint in fishery research.Based on Argo temperature and salinity profiles,this study applied the gradient-dependent optimal interpolation to reconstruct daily subsurface oceanic environmental information according to fishery dates and locations.The relationship between subsurface information and matching yellowfin tuna(YFT)in the western and central Pacific Ocean(WCPO)was examined using catch data from January 1,2008 to August 31,2017.The seawater temperature and salinity results showed differences of less than±0.5°C and±0.01 compared with the truth observations respectively.Statistical analysis revealed that the most suitable temperature for YFT fishery was 28–29°C at the near-surface.The most suitable salinity range for YFT fishery was 34.5–36.0 at depths shallower than 300 m.The suitable upper and lower bounds on the depths of the thermocline were 90–100 m and 300–350 m,respectively.The thermocline characteristics were prominent,with a mean temperature gradient exceeding 0.08°C/m.These results indicate that the profiles constructed by gradient-dependent optimal interpolation were more accurate than those of the nearest profiles adopted.展开更多
Based on the optimal interpolation objective analysis of the Argo data, improvements are made to the em- pirical formula of a background error covariance matrix widely used in data assimilation and objective anal- ysi...Based on the optimal interpolation objective analysis of the Argo data, improvements are made to the em- pirical formula of a background error covariance matrix widely used in data assimilation and objective anal- ysis systems. Specifically, an estimation of correlation scales that can improve effectively the accuracy of Ar- go objective analysis has been developed. This method can automatically adapt to the gradient change of a variable and is referred to as ＂gradient-dependent correlation scale method＂. Its effect on the Argo objective analysis is verified theoretically with Gaussian pulse and spectrum analysis. The results of one-dimensional simulation experiment show that the gradient-dependent correlation scales can improve the adaptability of the objective analysis system, making it possible for the analysis scheme to fully absorb the shortwave information of observation in areas with larger oceanographic gradients. The new scheme is applied to the Argo data obiective analysis system in the Pacific Ocean. The results are obviously improved.展开更多
为弥补渔场区次表层实时环境数据的不足,实验基于Argo剖面观测资料,采用梯度依赖最优插值方法,通过点对点的方式,反演了黑潮-亲潮交汇区柔鱼渔获点上温盐垂直结构,并利用理论检验、与实测数据对比等方法验证了反演结果的可靠性。结果显...为弥补渔场区次表层实时环境数据的不足,实验基于Argo剖面观测资料,采用梯度依赖最优插值方法,通过点对点的方式,反演了黑潮-亲潮交汇区柔鱼渔获点上温盐垂直结构,并利用理论检验、与实测数据对比等方法验证了反演结果的可靠性。结果显示,反演剖面相对于Argo原始观测数据,最大温度均方根误差不超过1℃,最大盐度均方根误差不超过0.4;而其与“淞航”号现场观测的温度、盐度绝对偏差分别小于0.25℃和0.27。同时,通过反演剖面分析了渔场区的温盐垂直结构及其与柔鱼单位捕捞努力量渔获量(Catch per unit effort,CPUE)的关系,结果表明,2018年8月和10月柔鱼在5 m水层的适宜温度分别为16和14℃,50 m水层降低至9~12℃,各水层的温度与CPUE的统计关系均符合一定曲率下的指数函数分布,且渔获点存在明显跃层,跃层强度变化越大,CPUE随机性也越大,渔获点跃层强度在0.4℃/m左右时CPUE相对稳定。而无论是哪个月份,较大CPUE都位于相对低盐区,即柔鱼偏向于在低盐海域活动。本研究可为构建长时间序列、准实时的渔场环境数据提供新思路,进而为深入研究渔场变迁动力机制提供必要的数据支撑。展开更多
Beam current dependence resulted from nonlinearity and asymmetry of the four channels of digital BPM(Beam Position Monitor) processor deteriorates the BPM performance.A systematic solution based on signal source calib...Beam current dependence resulted from nonlinearity and asymmetry of the four channels of digital BPM(Beam Position Monitor) processor deteriorates the BPM performance.A systematic solution based on signal source calibration tactics has been carried out to rectify this defect.It is optimized for implementation in FPGA.Mathematical illustrations of the calibration method,hardware and software design and implementation are presented.A signal source circuit using frequency synthesis technique is designed as calibration standard.Data acquisition system using JAVA web technology and Ethernet is introduced.Integrated FPGA implementation code architecture is presented,and experimental test results show that the method implemented in FPGA is feasible.Compared to other methods,our approach can rectify the nonlinearity and asymmetry simultaneously.The whole solution is integrated into the DBPM processor and can be executed online.展开更多
基金The National Natural Science Foundation of China under contract No.4210060098the Foundation of Key Laboratory of Sustainable Exploitation of Oceanic Fisheries Resources under contract No.A1-2006-21-200201.
文摘The current lack of high-precision information on subsurface seawater is a constraint in fishery research.Based on Argo temperature and salinity profiles,this study applied the gradient-dependent optimal interpolation to reconstruct daily subsurface oceanic environmental information according to fishery dates and locations.The relationship between subsurface information and matching yellowfin tuna(YFT)in the western and central Pacific Ocean(WCPO)was examined using catch data from January 1,2008 to August 31,2017.The seawater temperature and salinity results showed differences of less than±0.5°C and±0.01 compared with the truth observations respectively.Statistical analysis revealed that the most suitable temperature for YFT fishery was 28–29°C at the near-surface.The most suitable salinity range for YFT fishery was 34.5–36.0 at depths shallower than 300 m.The suitable upper and lower bounds on the depths of the thermocline were 90–100 m and 300–350 m,respectively.The thermocline characteristics were prominent,with a mean temperature gradient exceeding 0.08°C/m.These results indicate that the profiles constructed by gradient-dependent optimal interpolation were more accurate than those of the nearest profiles adopted.
基金The Marine Public Welfare Special Funds,the State Oceanic Administration of China under contract No.200705022the Technology Special Basic Work,the Ministry of Science and Technology under contract No.2012FY112300the Basic Scientific Research Special Funds of the Second Institute of Oceanography,the State Oceanic Administration of China under contract No.IT0904
文摘Based on the optimal interpolation objective analysis of the Argo data, improvements are made to the em- pirical formula of a background error covariance matrix widely used in data assimilation and objective anal- ysis systems. Specifically, an estimation of correlation scales that can improve effectively the accuracy of Ar- go objective analysis has been developed. This method can automatically adapt to the gradient change of a variable and is referred to as ＂gradient-dependent correlation scale method＂. Its effect on the Argo objective analysis is verified theoretically with Gaussian pulse and spectrum analysis. The results of one-dimensional simulation experiment show that the gradient-dependent correlation scales can improve the adaptability of the objective analysis system, making it possible for the analysis scheme to fully absorb the shortwave information of observation in areas with larger oceanographic gradients. The new scheme is applied to the Argo data obiective analysis system in the Pacific Ocean. The results are obviously improved.
文摘为弥补渔场区次表层实时环境数据的不足,实验基于Argo剖面观测资料,采用梯度依赖最优插值方法,通过点对点的方式,反演了黑潮-亲潮交汇区柔鱼渔获点上温盐垂直结构,并利用理论检验、与实测数据对比等方法验证了反演结果的可靠性。结果显示,反演剖面相对于Argo原始观测数据,最大温度均方根误差不超过1℃,最大盐度均方根误差不超过0.4;而其与“淞航”号现场观测的温度、盐度绝对偏差分别小于0.25℃和0.27。同时,通过反演剖面分析了渔场区的温盐垂直结构及其与柔鱼单位捕捞努力量渔获量(Catch per unit effort,CPUE)的关系,结果表明,2018年8月和10月柔鱼在5 m水层的适宜温度分别为16和14℃,50 m水层降低至9~12℃,各水层的温度与CPUE的统计关系均符合一定曲率下的指数函数分布,且渔获点存在明显跃层,跃层强度变化越大,CPUE随机性也越大,渔获点跃层强度在0.4℃/m左右时CPUE相对稳定。而无论是哪个月份,较大CPUE都位于相对低盐区,即柔鱼偏向于在低盐海域活动。本研究可为构建长时间序列、准实时的渔场环境数据提供新思路,进而为深入研究渔场变迁动力机制提供必要的数据支撑。
基金Supported by the National Natural Science Foundation of China(No.11075198)
文摘Beam current dependence resulted from nonlinearity and asymmetry of the four channels of digital BPM(Beam Position Monitor) processor deteriorates the BPM performance.A systematic solution based on signal source calibration tactics has been carried out to rectify this defect.It is optimized for implementation in FPGA.Mathematical illustrations of the calibration method,hardware and software design and implementation are presented.A signal source circuit using frequency synthesis technique is designed as calibration standard.Data acquisition system using JAVA web technology and Ethernet is introduced.Integrated FPGA implementation code architecture is presented,and experimental test results show that the method implemented in FPGA is feasible.Compared to other methods,our approach can rectify the nonlinearity and asymmetry simultaneously.The whole solution is integrated into the DBPM processor and can be executed online.
