Dynamics of a mesoscale eddy off Cape Ann, Massachusetts in May 2005     

Mingshun Jiang  Meng Zhou  Scott P. Libby  Donald M. Anderson 《Deep Sea Research Part I: Oceanographic Research Papers》2011,58(11):1130-1146

Observations and numerical modeling indicate that a mesoscale anti-cyclonic eddy formed south of Cape Ann at the northern entrance of Massachusetts Bay (MB) during May 2005, when large river discharges in the western Gulf of Maine and two strong Nor'easters passing through the regions led to an unprecedented toxic Alexandrium fundyense bloom (red tide). Both model results and field measurements suggest that the western Maine Coastal Current separated from Cape Ann around May 7–8, and the eddy formed on around May 10. The eddy was trapped at the formation location for about a week before detaching from the coastline and moving slowly southward on May 17. Both model results and theoretical analysis suggest that the separation of the coastal current from the coast and subsequent eddy formation were initiated at the subsurface by an adverse pressure gradient between Cape Ann and MB due to the higher sea level set up by onshore Ekman transport and higher density in downstream MB. After the formation, the eddy was maintained by the input of vorticity transported by the coastal current from the north, and local vorticity generation around the cape by the horizontal gradients of wind-driven currents, bottom stress, and water density induced by the Merrimack River plume. Observations and model results indicate that the anti-cyclonic eddy significantly changed the pathway of nutrient and biota transport into the coastal areas and enhanced phytoplankton including Alexandrium abundances around the perimeter of the eddy and in the western coast of MB.  相似文献   

The geomorphological features and continuity of the Kyushu-Palau Ridge (KPR)   总被引：4，自引：1，他引：3  

TANG Yong  LI Mingbi  LI Jiabiao  WU Zhaocai 《海洋学报(英文版)》2011,30(5):114-124

The Philippine Basin,surrounded by a series of oceanic trenches,is an independent deep ocean basin in the West Pacific Ocean.Its middle part is divided into three marginal sea sub-basins by the Kyushu-Palau and West Mariana Ridges,namely,the West Philippine Basin,the Shikoku and Parece Vela Basins and the Mariana Trough.This paper,through the analysis of the geomorphologic features and gravity and magnetic characteristics of the basin and identification of striped magnetic anomalies,suggests that the entire Philippine Basin developed magnetic lineation of oceanic nature,and therefore,the entire basin is of the nature of oceanic crust.The basin has developed a series of special geomorphic units with different shapes.The KPR runs through the entire Philippine Basin.From the view of geomorphologic features,the KPR is a discontinuous seamount chain (chain-shaped seamounts) and subduction beneath the Japanese Island arc at the Nankai Trough which is the natural boundary between the basin and the Japanese Island arc.At the positions of 25 N,24 N,23 N and 18 N,obvious discontinuity is shown,which belongs to natural topographic discontinuity.Therefore,the KPR is topographically discontinuous.  相似文献   

Influence of cavity shape on hydrodynamic noise by a hybrid LES-FW-H method     

王玉  王树新  刘玉红  陈超英 《中国海洋工程》2011,25(3):381-394

The flow past various mechanical cavity, which is a common structure on the surface of the underwater vehicle, and generating hydrodynamic noise has attracted considerable attention in recent years. In this paper, a hybrid method is presented to investigate the hydrodynamic noise induced by mechanical cavities with various shapes. With this method, the noise sources in the near wall turbulences or in the wake are computed by the large eddy simulation (LES) and the generation and propagation of the acoustic waves are solved by the Ffowcs Williams-Hawkings (FW-H) acoustic analogy method with acoustic source terms extracted from the time-dependent solutions of the unsteady flow. The feasibility and reliability of the current method was verified by comparing with experimental data (Wang, 2009). The 2D cavity models with different cross-section shapes and 3D cavity models with different cavity mouth shapes (rectangular and circular) are developed to study the influence of cavity shape on the hydrodynamic noise. By comparing the flow mechanisms, wall pressure fluctuations, near-field and far-field sound propagation distributions, it is found that the quadrangular cavity with equal depths of leading-edge and trailing-edge is preferred for its inducing lower hydrodynamic noise than the cylindrical cavity does.  相似文献   

海洋中尺度涡建模及其在水声传播影响研究中的应用   总被引：1，自引：0，他引：1  

李佳讯  张韧  陈奕德  金宝刚 《海洋通报》2011,30(1)

针对海洋中尺度涡对水声传播的影响,利用中尺度涡区的历史水文实测数据提取涡旋强度,空间尺度等中尺度涡特征参数,建立了海洋中尺度涡理论计算模型。运用MMPE水下声场模型仿真试验研究了涡旋性质、强度和位置、声源频率和置放深度对声传播特性的影响。结果表明:暖涡使得会聚区的位置后退,会聚区宽度增加;冷涡使得会聚区的位置前移,会聚区宽度减小。涡旋的强度越大,前移或后退的效应越显著。  相似文献   

台湾以东黑潮锋的中尺度过程研究     

李威  王琦  马继瑞  韩桂军  张学峰 《海洋通报》2011,30(5):518-528

采用海洋再分析结果,研究了海洋涡旋和锋面波动对台湾以东黑潮锋的影响,结果表明,Rossby波第一斜压模态形成的冷涡(暖涡),减弱(增强)台湾以东黑潮温度锋强度,减小(加大)锋的宽度.在再分析结果中,捕获到1991年1-2月台湾以东的一次黑潮锋面波动.锋面波动的波槽(波脊)到达时,该温度锋强度减弱(增强),宽度和厚度减小...  相似文献   

基于全产业链的我国文化旅游发展模式研究   总被引：2，自引：0，他引：2  

马勇  王宏坤 《世界地理研究》2011,(4):143-148

随着近年来我国文化产业和旅游产业都被提升到重要战略地位,文化旅游作为两大产业相融合的产物迅速发展,各地兴建了大量文化旅游项目,但其发展模式依旧停留在传统的基础层面。因此,本文从全产业链的视角出发,提出了文化旅游产业链双核驱动发展模式、文化旅游产业链横向拓展发展模式、文化旅游产业链纵向延伸发展模式。希望进一步推动我国大力实施文化旅游发展战略,通过旅游项目彰显地方文化特色。  相似文献   

循环经济理念下新型稻米加工企业产业链的构建   总被引：1，自引：0，他引：1  

陈婷  林瑞余  林文雄 《资源与生态学报(英文版)》2011,2(1):51-55

在对我国目前稻米加工业发展现状进行分析的基础上,针对目前稻米加工业精深加工水平不高,资源利用率低等问题,提出以循环经济理念为指导,构建稻米加工业新型产业链的思路,并以具体的稻米加工企业为案例,对稻米加工业发展循环经济的经济效益与生态效益、社会效益进行分析,为同类行业发展循环经济提供有利借鉴。  相似文献   

Generation of unusual branched long chain alkanes from hydrous pyrolysis of anammox bacterial biomass     

《Organic Geochemistry》2014

Anammox, the microbial anaerobic oxidation of NH₄⁺ by NO₂⁻ to produce N₂, is recognised as a key process in the marine, freshwater and soil N cycles, and has been found to be a major sink for fixed inorganic N in the ocean. Ladderane lipids are unique anammox bacterial membrane lipids used as biomarkers for such bacteria in recent and past environmental settings. However, their fate during diagenesis and early catagenesis is not well constrained. In this study, hydrous pyrolysis experiments were performed on anammox bacterial biomass and the generated aliphatic hydrocarbons, present in oil generated at 220–365 °C, were analysed. A unique class of hydrocarbons was detected, and a representative component was isolated and rigorously identified using 2D nuclear magnetic resonance (NMR) spectroscopy. It consisted of C₂₄ to C₃₁ branched long chain alkanes with two internal ethyl and/or propyl substituents. The alkanes were generated above 260 °C, with maximum generation at 320 and 335 °C. Their stable carbon isotopic values were depleted in ¹³C, similar to carbon isotope values of the original anammox lipids, indicating that they were thermal products generated from lipids of anammox bacterial biomass. A range of sediments from different geological periods where anammox may have been an important process was screened for the presence of these compounds as possible catagenetic products. They were not detected, either because the concentration was too low, or the sediments screened were too immature for them to have been generated, or because the artificially produced products of anammox lipids may not reflect the natural diagenetic and catagenetic products of ladderane lipids.  相似文献   

Modeling the particle breakage of rockfill materials with the cohesive crack model     

《Computers and Geotechnics》2014

A practical combined finite–discrete element method was developed to simulate the breakage of irregularly shaped particles in granular geomaterials, e.g., rockfill. Using this method, each particle is discretized into a finite element mesh. The potential fracture paths are represented by pre-inserted cohesive interface elements (CIEs) with a progressive damage model. The Mohr–Coulomb model with a tension cut-off is employed as the damage initiation criterion to rupture the predominant failure mode occurs at the particle scale. Two series of biaxial tests were simulated for both the breakable and unbreakable particle assemblies. The two assemblies have identical configurations, with the exception that the former is inserted with CIEs and is breakable. The simulated stress–strain–dilation responses obtained for both assemblies are in agreement with experimental observations. We present a comprehensive study of the role of particle breakage on the mechanical behavior of rockfill materials at both the macroscopic and microscopic scales. The underlying mechanism of particle breakage can be explained by the force chain in the assemblies.  相似文献   

中国区际价值链协作的网络特征与空间格局及其演变——基于增加值分解和复杂网络的分析     

陆长玮 《地理科学》2022,42(2):256-263

利用增加值分解和复杂网络分析方法,基于2007年、2010年和2012年的省际投入产出表,构建中国区际价值链协作网络,考察区际价值链协作的网络特点与空间格局及其演变。结果表明,中国区际价值链协作存在显著的网络特点,显示出小世界网络特征;各地区的网络中心性有明显的地区差异,且该差异在不断缩小,而工业化水平等是引起节点网络中心性地区差异的重要因素。节点聚类和社区划分的结果发现,中国区际价值链协作网络存在3~4个网络社区,地区间的局部网络互动显著;且各网络社区内部的节点地区表现出显著的空间毗邻与地理成片,特别是上海等8个地区在网络中的局部互动最为稳定。  相似文献