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| 1 | Recognition on the forming-vanishing process and underlying mechanisms of the hypoxia off the Yangtze River estuary显示文摘On the basis of compiled multidisciplinary historical data in 2006–2007 and incorporation of relevant simulation results and remote sensing data, we performed an in-depth study of the generation and dissipation process of the hypoxic zone and its distribution morphology and structure off the Yangtze River estuary. Based on the hydrological circulation dynamics, reproduction of phytoplankton(leading to the decomposition of organic matter), and other factors, we comprehensively and systematically investigated the generation and dissipation of the hypoxic zone and underlying mechanisms for the seasonal variation in its position, explored the multi-factorial synergistic reactions during the generation and dissipation process of the hypoxic zone, and revealed the controlled mechanism for the morphology and structure of the hypoxic zone's distribution. Our studies indicate that in the winter and spring seasons, the hydrological environment off the Yangtze River estuary provides a water body with relatively low contents of dissolved oxygen(DO), which is the background for the formation of a hypoxic zone. After entering into the summer season, the hypoxic zone gradually develops towards the north and becomes mature. Because of the impact of the terrain, local decomposition of organic matter, and upwelling of the Kuroshio subsurface water in July–August, the hypoxic zone off the Yangtze River estuary exhibits the characteristics of discontinuous distribution in space and has a south and north 'dual-core' structure in the inner continental shelf. In addition, there is a hypoxic core in the eastern outer continental shelf. The degrees of hypoxia vary for different areas; they are strongest overall in the north, next strongest in the south; they are weakest on the outer continental shelf. In summer, the hypoxic zone in the north is related to the northward differentiation of the southern hypoxic zone and results from local development and intensification. In August, the hypoxic zone in the north reaches its peak, and after September, it rapidly retreats southward and disappears because of weakening stratification. In the fall, there is hypoxic zone along the coast of Zhejiang in the south, and there is also a low-DO area to the southwest of Jeju Island, with both zones disappearing rapidly. In addition, the change of dynamic environment also causes the low-DO area of the outer continental shelf to move outward in the fall. The variation in the intensity of the stratification and its cumulative effects as a barrier of vertical DO transportation over long periods of time have a significant impact on the degree of hypoxia in the hypoxic zone. In addition, the seasonal variations in the size of the stratified region, intensity of each current system/water mass, upwelling, front, and high-value area of phytoplankton biomass jointly restrict the extension of the hypoxic zone in the inner continental shelf and latitudinal(south-north direction) movement of its location off the Yangtze River estuary. The combined effect of dynamic factors, such as that of the Kuroshio subsurface water, causes a low-DO core in the outer continental shelf. The bottom cold water to the north of the East China Sea is the dynamic basis for the formation of the low-DO area to the southwest of Jeju Island during the fall season. The special seabed topography and mud area distribution off the Yangtze River estuary have a certain degree of influence on the development of the hypoxic zone. The generation and dissipation of the hypoxic zone and its distribution morphology off the Yangtze River estuary, and seasonal variation of its structure and position are a result of the synergistic effects of various factors. | WEI QinSheng WANG BaoDong CHEN JianFang XIA ChangShui QU DaPeng XIE LinPing | 2015 | Science China Earth Sciences2015,58,4: | 15 |
| 2 | The Roles of Different Mechanisms Related to the Tide-induced Fronts in the Yellow Sea in Summer显示文摘In summer, the Yellow Sea Cold Water Mass(YSCWM) is a stable water mass of low temperature lying at the bottom of the central Yellow Sea(YS). It is fringed by some typical tidal fronts, which separate deep, stratified water on the offshore side from the well-mixed, shallow water on the inshore side. Three striking fronts—Subei Bank Front(SBF), Shandong Peninsula Front(SPF), and Mokpo Front(MKF; a front off the southwestern tip of the Korean Peninsula)—have been identified by various studies from both satellite observations and model results. Tide plays an important role in the formation and maintenance of these fronts. However, it is still a matter of debate as to the roles these two kinds of mechanisms of upwelling and tidal mixing play, and how importance they are in the maintenance processes of the above three fronts. Basing a nested high-resolution model HYCOM(the Hybrid Coordinate Ocean Model), this study focuses on the different mechanisms of tidal effects on the thermal fronts in the YS in summertime. Through comparative experiments with and without tidal forcing,the results indicate that the MKF is mainly driven by tide-induced upwelling. For the SPF, tidal mixing is the dominant factor,when lower cold water is stirred upwards along the sloping topography of the western YS. Meanwhile, the combined effect of upwelling and tidal mixing is the main cause of the formation of the SBF. Diagnostic analysis of thermal balance shows that horizontal nonlinear advection induced by strong tidal currents also contributes to the thermal balance of frontal areas. | REN Shihe XIE Jiping ZHU Jiang | 2014 | Advances in Atmospheric Sciences2014,31,5: | 7 |
| 3 | Mechanisms leading to the frequent occurrences of hypoxia and a preliminary analysis of the associated acidification off the Changiiang estuary in summer显示文摘Based on literature data and shipboard observations,this study investigated the main environmental characteristics of the seafloor topography,current field,front,and upwelling that are closely related to hypoxia occurrence off the Changjiang estuary.The physical processes of the plume front and upwelling off the Changjiang estuary in summer were coupled.The vertical distribution pattern of the plume front was closely related to the upwelling.By reviewing and analyzing the historical summer hypoxia events off the Changjiang estuary,we statistically demonstrated the spatial structure of the horizontal distribution of the hypoxic zone and investigated the location of occurrence zone of the hypoxia.We found that the dissolved oxygen(DO)concentration on the inner continental shelf off the estuary showed a'V'shape in relation to station depth.Therefore,we noted that the hypoxic water on the inner continental shelf mostly occurred on the slopes with steep seafloor topography.Base on the current understanding of the hypoxic mechanisms off the Changjiang estuary,we analyzed the biogeochemical mechanisms that could cause the steep terrain off the Changjiang estuary to become the main areas prone to summer hypoxia and explained the internal relations between the location of the hypoxic zone on the slopes and the plume front and upwelling.The plume front and upwelling off the Changjiang estuary and their coupling were important driving forces of summer hypoxia.The continuous supply of nutrients affected by the interaction of the plume front extension of the Changjiang Diluted Water(CDW)and upwelling and the favorable light conditions were important mechanisms causing the phytoplankton blooms and benthic hypoxia off the Changjiang estuary in summer.By analyzing oxygen utilization,organic carbon mineralization,and nutrient regeneration in the hypoxic zone,we observed that the significant oxygen utilization process off the Changjiang estuary in summer also mainly occurred near the steep slopes with front and upwelling features and confirmed the apparent nutrient loss in the benthic hypoxic zone.Meanwhile,our analysis revealed that the sediment resuspension in the benthic boundary layer in the mud areas off the Changjiang estuary could also affect the oxygen utilization and mineralization of organic carbon and nutrient recycling and regeneration.This study also demonstrated that the steep terrain off the Changjiang estuary was the main location for summer acidification,and the coupling between the plume front and upwelling on the steep slopes was an important physical driving force inducing summer benthic acidification.Finally,we discussed issues to address in future studies of the hypoxic zone and water acidification off the Changjiang estuary. | WEI QinSheng WANG BaoDong YU ZhiGang CHEN JianFang XUE Liang | 2017 | Science China Earth Sciences2017,60,2: | 5 |
| 4 | 长江口及邻近海域底层水体低氧物理机制的研究进展显示文摘人类活动和自然因素共同但有区别的作用引起了长江口及邻近海域富营养化,造成夏季底层水体低氧现象加剧,成为近海生态健康恶化的重要征兆。本文梳理了国内外学者在该海域低氧研究中获得的重要认识,分析了底层水体溶解氧的潮周期尺度、事件尺度和年际尺度的变化特征,重点从层化与物质输运角度,介绍了长江冲淡水、台湾暖流、海洋锋面、风和潮等过程影响底层水体中氧气消耗或补充的机制,揭示了本海域主要低氧现象分别位于长江口和浙江近海的特征,对比了两处低氧区形成与演变的异同机制。目前,对低氧形成机制的定性认识和多尺度变化特征的了解已经有较好的基础,未来需要从多学科交叉角度加强现场试验和定量研究,掌握低氧的长期演变趋势,研发底层水体低氧的预测预警技术,支撑我国河口近海的生态预警监测工作。 | 周锋 钱周奕 刘安琪 马晓 倪晓波 曾定勇 | 2021 | 海洋学研究2021,39,4: | 3 |
| 5 | 基于水动力ROMS与BOX耦合模型的长江口及邻近水域水通量及水体交换特性显示文摘本研究将水动力模型ROMS(regional oceanic modeling system,区域海洋模式系统)与箱式(box)模型结合,详细阐述了长江口及邻近水域四个季节的水通量特征及水体交换特性。研究发现:总的水通量整体受季风控制,季风的作用在于使水体在南北方向上交替输送,而台湾暖流对春夏季底层水南向输运具有重要作用;直接进入123.5°E以东外海区域的水通量很小,而是先从南边界流出研究区域,然后通过海洋环流系统进入外海。在强烈季风下,水体更新依赖于季风方向的水平通量,主要是同层水体而不是表底层水体之间的交换。虽然水体更新时间较长的区域与缺氧区基本一致,但本研究认为该区域底层水体缺氧的本质原因是跃层阻隔了表底层水体之间的交换。 | 王晓红 俞志明 樊伟 宋秀贤 曹西华 袁涌铨 | 2015 | 海洋与湖沼2015,46,1: | 3 |
| 6 | On summer stratification and tidal mixing in the Taiwan Strait显示文摘在大陆人架上,把海分开成混合得好、成层的地区的前面通常由于潮汐的混合的空间变化在温暖的季节被形成。在这份报纸,使用八年在 situ 水道学的观察,海表面温度( SST )的卫星图象和叶绿素--一( Chl --一)一个潮汐的模型的集中,和结果,我们在潮汐的混合上在台湾海峡和它的依赖调查夏天层化, upwelling ,和河冲淡了水羽毛。在海峡的大多数区域,在决定 thermohaline 结构的潮汐的混合的主导的角色被在二之间的关联证实;然而,在 thermohaline 结构由于 upwelling 和河的重要影响以不同方法变化的地方,有一些区域冲淡的水羽毛。混合得好的区域主要在台湾河岸上并且在被散布近海区域离开 Dongshan 岛, Nanao 岛,和 Pingtan 岛,当北、中央的台湾海峡和台湾河岸的区域南方被成层时。为这个区域的批评 Simpson 猎人参数被估计是 1.78 .[ 出版摘要] | Jia ZHU Jianyu HU Zhiyu LIU | 2013 | Frontiers of Earth Science2013,7,2: | 3 |
| 7 | Reconstruction of eddies by assimilating satellite altimeter data into Princeton Ocean Model显示文摘An optimal interpolation assimilation model for satellite altimetry data is developed based on Princeton Ocean Model(POM),which is applied in a quasi-global domain,by the method of isotropic correlation between sea level anomaly(SLA) and sea temperature anomaly. The performance of this assimilation model is validated by the modeled results of SLA and the current patterns. Comparisons between modeling and satellite data show that both the magnitudes and distribution patterns of the simulated SLA are improved by assimilation. The most significant improvement is that meso-scale systems,e.g.,eddies,are well reconstructed. The evolution of an eddy located in the northwest Pacific Ocean is traced by using the assimilation model. Model results show that during three months the eddy migrated southwestward for about 6 degrees before merging into the Kuroshio. The three dimensional structure of this eddy on 12 August 2001 is further analyzed. The strength of this warm,cyclonic eddy decreases with the increase of depth. The eddy shows different horizontal patterns at different layers,and the SLA and temperature fields agree with each other well. This study suggests that this kind of data assimilation is economic and reliable for eddy reconstruction,and can be used as a promising technique in further studies of ocean eddies as well as other fine circulation structures. | YIN Xunqiang QIAO Fangli XIA Changshui LU Xin'gang YANG Yongzeng | 2010 | Acta Oceanologica Sinica2010,29,1: | 1 |
| 8 | A numerical study of the effect of the marginal sea on coastal upwelling in a non-linear inertial model显示文摘Inertia theory and the finite element method are used to investigate the effect of marginal seas on coastal upwelling. In contrast to much previous research on wind-driven upwelling, this paper does not consider localized wind effects, but focuses instead on temperature stratification, the slope of the continental shelf, and the background flow field. Finite element method, which is both faster and more robust than finite difference method in solving problems with complex boundary conditions, was developed to solve the partial differential equations that govern coastal upwelling. Our results demonstrate that the environment of the marginal sea plays an important role in coastal upwelling. First, the background flow at the outer boundary is the main driving force of upwelling. As the background flow strengthens, the overall velocity of cross-shelf flow increases and the horizontal scale of the upwelling front widens, and this is accompanied by the movement of the upwelling front further offshore. Second, temperature stratification determines the direction of cross-shelf flows, with strong stratification favoring a narrow and intense upwelling zone. Third, the slope of the continental shelf plays an important role in controlling the intensity of upwelling and the height that upwelling may reach: the steeper the slope, the lower height of the upwelling. An additional phenomenon that should be noted is upwelling separation, which occurs even without a local wind force in the nonlinear model. | CHAO JiPing KANG YanYan LI JianPing | 2014 | Science China Earth Sciences2014,57,11: | 0 |
| 9 | Nutrient fluxes in the Changjiang River estuary and adjacent waters——a modified box model approach显示文摘To solve nutrient flux and budget among waters with distinct salinity difference for water-saltnutrient budget,a traditional method is to build a stoichiometrically linked steady state model.However,the traditional way cannot cope appropriately with those without distinct salinity difference that parallel to coastline or in a complex current system,as the results would be highly affected by box division in time and space,such as the Changjiang(Yangtze) River estuary(CRE) and adjacent waters(30.75°-31.75°N,122°10′-123°20′E).Therefore,we developed a hydrodynamic box model based on the traditional way and the regional oceanic modeling system model(ROMS).Using data from four cruises in 2005,horizontal,vertical and boundary nutrient fluxes were calculated in the hydrodynamic box model,in which flux fields and the major controlling factors were studied.Results show that the nutrient flux varied greatly in season and space.Water flux outweighs the nutrient concentration in horizontal flux,and upwelling flux outweighs upward diffusion flux in vertical direction(upwelling flux and upward diffusion flux regions overlap largely all the year).Vertical flux in spring and summer are much greater than that in autumn and winter.The maximum vertical flux for DIP(dissolved inorganic phosphate) occurs in summer.Additional to the fluxes of the Changjiang River discharge,coastal currents,the Taiwan Warm Current,and the upwelling,nutrient flux inflow from the southern Yellow Sea and outflow southward are found crucial to nutrient budgets of the study area.Horizontal nutrient flux is controlled by physical dilution and confined to coastal waters with a little into the open seas.The study area acts as a conveyer transferring nutrients from the Yellow Sea to the East China Sea in the whole year.In addition,vertical nutrient flux in spring and summer is a main source of DIP.Therefore,the hydrodynamic ROMS-based box model is superior to the traditional one in estimating nutrient fluxes in a complicated hydrodynamic current system and provides a modified box model approach to material flux research. | 王晓红 俞志明 樊伟 宋秀贤 曹西华 袁涌铨 | 2015 | Chinese Journal of Oceanology and Limnology2015,33,1: | 0 |