Variations of the particulate organic carbon and nitrogen （POC/PN） along the PN section in the East China Sea （ECS） were examined based on POC/PN data obtained in September 2002. A comparison with others work indi...Variations of the particulate organic carbon and nitrogen （POC/PN） along the PN section in the East China Sea （ECS） were examined based on POC/PN data obtained in September 2002. A comparison with others work indicates that POC is the highest in summer, followed by autumn and spring, and the lowest in winter. Generally, POC concentration decreases seawards, and the in situ productivity in September plays an important role in POC distribution. POC in the PN section is composed of terrestrial, resuspended, in situ produced carbon and carbon originated fi＇om the Kuroshio waters. The Changjiang River effects the ECS in the PN section, but the influence is mainly minimiged beyond 123.5° E because of barrier effect. The impact of Kuroshio subsurface water （KSSW） over shelf break can also effect POC distribution, with high POC concentration there.展开更多
In this paper, we use the conductivity-temperature-depth (CTD) observation data and a three-dimensional ocean model in a seasonally-varying forcing field to study the barrier layer (BL) in the PN section in the East C...In this paper, we use the conductivity-temperature-depth (CTD) observation data and a three-dimensional ocean model in a seasonally-varying forcing field to study the barrier layer (BL) in the PN section in the East China Sea (ECS). The BL can be found along the PN section with obviously seasonal variability. In winter, spring and autumn, the BL occurs around the slope where the cold shelf water meets with the warm Kuroshio water. In summer, the BL can also be found in the shelf area near salinity front of the Changjiang (Yangtze) River Dilution Water (YRDW). Seasonal variations of BL in the PN section are caused by local hydrological characteristics and seasonal variations of atmospheric forcing. Strong vertical convection caused by sea surface cooling thickens the BL in winter and spring in the slope area. Due to the large discharge of Changjiang River in summer, the BL occurs extensively in the shelf region where the fresh YRDW and the salty bottom water meet and form a strong halocline above the seasonal thermocline. The formation mechanism of BL in the PN section can be explained by the vertical shear of different water masses, which is called the advection mechanism. The interannual variation of BL in summer is greatly affected by the YRDW. In the larger YRDW year (such as 1998), a shallow but much thicker BL existed on the shelf area.展开更多
The horizontal flux of biogenic elements through PN section in April 1994 was calculated in the present paper using output of the OPYC model, which is a very general global model solving the full primitive equations f...The horizontal flux of biogenic elements through PN section in April 1994 was calculated in the present paper using output of the OPYC model, which is a very general global model solving the full primitive equations forced by the atmospheric wind stress, observed heat flux, freshwater flux and cloudiness including a sea ice model both poles with rheology. However, since it is a global model, its resolution is rather coarse, less than 1°×1° horizontally and only 1 layer on continental shelf and 7 layers in the Okinawa Trough. We reconstructed the velocity profiles by ocean current modes evaluated from the hydrographic data along PN section and then used it to determine the flux of biogenic elements with the data collected during the Japanese cruise K94-04. The results shown that the volume transport was about 33×10 12 cm 3/s consistent with the OPYC model output, the maximum nitrate and phosphate flux densities were right on the shelf margin at the depth of about 300 m with the total fluxes 1.95×10 5 and 0.15×10 5 mol/s, respectively, the maximum dissolved oxygen and total carbon dioxide flux densities were on the surface layer near western side of the shelf margin and in the thermocline near the eastern side of the shelf margin with the total fluxes 1.43×10 8 L/s and 0.69×10 8 mol/s,respectively, through PN section in April 1994.展开更多
Sectional velocity distribution of the East China Sea Kuroshio is one of the basic points in the study of the Kuroshio. Hydrographic temperature and salinity data at G-PN section in the East China Sea from June 1955 t...Sectional velocity distribution of the East China Sea Kuroshio is one of the basic points in the study of the Kuroshio. Hydrographic temperature and salinity data at G-PN section in the East China Sea from June 1955 to November 2001 are collected and properly processed to calculate the geostrophic cur-rent using dynamic height method at the transect of the Kuroshio. After analysis of calculation results, the basic current structure of the Kuroshio in its main part is examined together with scalar estimate and char-acters of multi- core structure, and spacial-temporal variations of current cores’ position. Main result shows that (1) single-core structure, double-core structure and multi-core structure are basic forms in axial part of the Kuroshio; (2) abvious temporal varia-tions exist in current structure of the Kuroshio; (3) the current of structure of the Kuroshio has distinctly seasonal association. The number of current cores is on the high side of core numbers in average and multi-core stucture appears in fall mostly.展开更多
The seasonal and interannual variations of the vertical distribution of the Kuroshio velocity and its formative mechanism were studied by analyzing the Global Ocean Reanalysis Simulation 2 （GLORYS2） dataset in the P...The seasonal and interannual variations of the vertical distribution of the Kuroshio velocity and its formative mechanism were studied by analyzing the Global Ocean Reanalysis Simulation 2 （GLORYS2） dataset in the Pollution Nagasaki （PN） section （126.0°E-128.2°, at depths less than 1000 m）. The results indicated that： 1） the maximum transport in the PN section occurs in summer, followed by spring, and the minimum transport occurs in fall and winter; the maximum velocities are located at the subsurface in both winter and summer and velocities are relatively larger and at a shallower depth in summer; and the velocity core is located at the surface in spring and fall. The isopycnic line has a clear depression around the Kuroshio axis in winter. The depth of maximum velocity and the zero horizontal density gradients both exhibit substantial seasonal and interannual variations, and the interannual variations are larger. 2） The distributions of velocity and density are in accordance with the therma~ wind relation. Although Kuroshio transport is determined by the large-scale wind field and mesoscale motion in the Pacific Ocean; local heat flux and thermohaline circulation influence the density field, modify the vertical structure of the Kuroshio velocity, and adjust the allocation of water fluxes and nutrients transport. 3） Shelf-water offshore transport into the Kuroshio upper layer induced by southwest monsoons might contribute to the maximum velocity up to the surface in summer. Nonlinear and nongeostrophic processes are not considered in the present study, and the thermal wind relation accounts for part of the vertical structure of the Kuroshio velocity.展开更多
本文首先分析比较了常用的声场仿真算法,利用海底起伏地形下的实验数据对BELLHOP模型进行了校核和评估;其次,选择东海PN剖面典型起伏地形海域,利用OFES(OGCM for the Earth Simulator)模式数据,采用自组织神经网络方法获得海洋温度、盐...本文首先分析比较了常用的声场仿真算法,利用海底起伏地形下的实验数据对BELLHOP模型进行了校核和评估;其次,选择东海PN剖面典型起伏地形海域,利用OFES(OGCM for the Earth Simulator)模式数据,采用自组织神经网络方法获得海洋温度、盐度、深度和声速典型参数;最后,利用BELLHOP模型分别对假设平坦地形和真实起伏地形下的PN剖面声场传播过程进行仿真,给出了水声传播衰减数据,对比和分析了真实海洋地形对水声信道传播的影响效应。结果表明,BELLHOP 算法仿真结果与实验数据相吻合,在海底起伏地形下具有较好的适用性,可用于声传播特性的预测;对于海洋水声信道,较为复杂的海底地形会对声道轴和传输损失造成较为明显的影响;不同深度条件下,海底起伏地形造成的影响有所不同。展开更多
文摘Variations of the particulate organic carbon and nitrogen （POC/PN） along the PN section in the East China Sea （ECS） were examined based on POC/PN data obtained in September 2002. A comparison with others work indicates that POC is the highest in summer, followed by autumn and spring, and the lowest in winter. Generally, POC concentration decreases seawards, and the in situ productivity in September plays an important role in POC distribution. POC in the PN section is composed of terrestrial, resuspended, in situ produced carbon and carbon originated fi＇om the Kuroshio waters. The Changjiang River effects the ECS in the PN section, but the influence is mainly minimiged beyond 123.5° E because of barrier effect. The impact of Kuroshio subsurface water （KSSW） over shelf break can also effect POC distribution, with high POC concentration there.
基金Supported by National Basic Research Program of China (973 Program, No. 2005CB422303 and 2007CB411804)the Key Project of the International Science and Technology Cooperation Program of China (No. 2006DFB21250)+1 种基金the "111 Project" of the Ministry of Education (No. B07036)the Program for New Century Excellent Talents in University, China (No. NECT-07-0781)
文摘In this paper, we use the conductivity-temperature-depth (CTD) observation data and a three-dimensional ocean model in a seasonally-varying forcing field to study the barrier layer (BL) in the PN section in the East China Sea (ECS). The BL can be found along the PN section with obviously seasonal variability. In winter, spring and autumn, the BL occurs around the slope where the cold shelf water meets with the warm Kuroshio water. In summer, the BL can also be found in the shelf area near salinity front of the Changjiang (Yangtze) River Dilution Water (YRDW). Seasonal variations of BL in the PN section are caused by local hydrological characteristics and seasonal variations of atmospheric forcing. Strong vertical convection caused by sea surface cooling thickens the BL in winter and spring in the slope area. Due to the large discharge of Changjiang River in summer, the BL occurs extensively in the shelf region where the fresh YRDW and the salty bottom water meet and form a strong halocline above the seasonal thermocline. The formation mechanism of BL in the PN section can be explained by the vertical shear of different water masses, which is called the advection mechanism. The interannual variation of BL in summer is greatly affected by the YRDW. In the larger YRDW year (such as 1998), a shallow but much thicker BL existed on the shelf area.
文摘The horizontal flux of biogenic elements through PN section in April 1994 was calculated in the present paper using output of the OPYC model, which is a very general global model solving the full primitive equations forced by the atmospheric wind stress, observed heat flux, freshwater flux and cloudiness including a sea ice model both poles with rheology. However, since it is a global model, its resolution is rather coarse, less than 1°×1° horizontally and only 1 layer on continental shelf and 7 layers in the Okinawa Trough. We reconstructed the velocity profiles by ocean current modes evaluated from the hydrographic data along PN section and then used it to determine the flux of biogenic elements with the data collected during the Japanese cruise K94-04. The results shown that the volume transport was about 33×10 12 cm 3/s consistent with the OPYC model output, the maximum nitrate and phosphate flux densities were right on the shelf margin at the depth of about 300 m with the total fluxes 1.95×10 5 and 0.15×10 5 mol/s, respectively, the maximum dissolved oxygen and total carbon dioxide flux densities were on the surface layer near western side of the shelf margin and in the thermocline near the eastern side of the shelf margin with the total fluxes 1.43×10 8 L/s and 0.69×10 8 mol/s,respectively, through PN section in April 1994.
文摘Sectional velocity distribution of the East China Sea Kuroshio is one of the basic points in the study of the Kuroshio. Hydrographic temperature and salinity data at G-PN section in the East China Sea from June 1955 to November 2001 are collected and properly processed to calculate the geostrophic cur-rent using dynamic height method at the transect of the Kuroshio. After analysis of calculation results, the basic current structure of the Kuroshio in its main part is examined together with scalar estimate and char-acters of multi- core structure, and spacial-temporal variations of current cores’ position. Main result shows that (1) single-core structure, double-core structure and multi-core structure are basic forms in axial part of the Kuroshio; (2) abvious temporal varia-tions exist in current structure of the Kuroshio; (3) the current of structure of the Kuroshio has distinctly seasonal association. The number of current cores is on the high side of core numbers in average and multi-core stucture appears in fall mostly.
文摘The seasonal and interannual variations of the vertical distribution of the Kuroshio velocity and its formative mechanism were studied by analyzing the Global Ocean Reanalysis Simulation 2 （GLORYS2） dataset in the Pollution Nagasaki （PN） section （126.0°E-128.2°, at depths less than 1000 m）. The results indicated that： 1） the maximum transport in the PN section occurs in summer, followed by spring, and the minimum transport occurs in fall and winter; the maximum velocities are located at the subsurface in both winter and summer and velocities are relatively larger and at a shallower depth in summer; and the velocity core is located at the surface in spring and fall. The isopycnic line has a clear depression around the Kuroshio axis in winter. The depth of maximum velocity and the zero horizontal density gradients both exhibit substantial seasonal and interannual variations, and the interannual variations are larger. 2） The distributions of velocity and density are in accordance with the therma~ wind relation. Although Kuroshio transport is determined by the large-scale wind field and mesoscale motion in the Pacific Ocean; local heat flux and thermohaline circulation influence the density field, modify the vertical structure of the Kuroshio velocity, and adjust the allocation of water fluxes and nutrients transport. 3） Shelf-water offshore transport into the Kuroshio upper layer induced by southwest monsoons might contribute to the maximum velocity up to the surface in summer. Nonlinear and nongeostrophic processes are not considered in the present study, and the thermal wind relation accounts for part of the vertical structure of the Kuroshio velocity.
文摘本文首先分析比较了常用的声场仿真算法,利用海底起伏地形下的实验数据对BELLHOP模型进行了校核和评估;其次,选择东海PN剖面典型起伏地形海域,利用OFES(OGCM for the Earth Simulator)模式数据,采用自组织神经网络方法获得海洋温度、盐度、深度和声速典型参数;最后,利用BELLHOP模型分别对假设平坦地形和真实起伏地形下的PN剖面声场传播过程进行仿真,给出了水声传播衰减数据,对比和分析了真实海洋地形对水声信道传播的影响效应。结果表明,BELLHOP 算法仿真结果与实验数据相吻合,在海底起伏地形下具有较好的适用性,可用于声传播特性的预测;对于海洋水声信道,较为复杂的海底地形会对声道轴和传输损失造成较为明显的影响;不同深度条件下,海底起伏地形造成的影响有所不同。
