基于拉格朗日拟序结构的黑潮区域海流运输结构提取和分析     

田丰林  任一丹  何遒  陈戈 《海洋学报》2020,42(5):12-21

海流的拉格朗日运动对于研究物质输送有着重要意义,拉格朗日拟序结构(LCSs)作为研究海流结构的新型方法,相比于传统欧拉方法更为客观。本文提出了一种新的计算LCSs束的方法,基于25年的平均速度场,利用变分方法计算得到黑潮区域的气候态LCSs,并通过简化合并的方法得到了气候态LCSs束,该LCSs束能够突出地显示出海流特性和运输模式,其代表的平均拉格朗日环流有很强的约束作用,且具有鲁棒性。最终我们获得了气候态下12个月份的流场结构图,揭示了月周期性拉格朗日环流规律。本文还利用虚拟粒子输运、多年浮标轨迹以及气候态温盐异常3种方法进行了验证,与拉格朗日运输模式相吻合,证明了海流拉格朗日拟序结构的准确性和可靠性。  相似文献   

基于拉格朗日拟序结构的吕宋海峡表层水交换研究     

郑哲昊  庄伟  胡建宇  吴泽轮  刘长建 《海洋学报(英文版)》2020,39(11):21-32

黑潮通过吕宋海峡入侵南海呈现明显的瞬态特征。以往的研究通常将黑潮在吕宋海峡附近的流态分为几种不同类型。本文基于表层地转流计算得到的有限时间李雅普诺夫指数场（FTLE）,展示了拉格朗日视角下的吕宋海峡上层水交换特征。从FTLE场提取的拉格朗日拟序结构（LCSs）很好地识别了吕宋海峡附近的典型流态和旋涡活动。此外,这些LCSs还揭示了吕宋海峡周围复杂的输运路径和流体域,这些特征得到了卫星跟踪浮标轨迹的验证,且从流速场中是无法直接识别的。FTLE场显示,吕宋海峡附近表层水体的输运形态主要可分为四类。其中,黑潮直接向北流动的“跨越”形态和顺时针旋转的“流套”形态的发生频次明显高于直接进入南海的黑潮分支“渗入”形态和南海水流出至太平洋的“外流”形态。本文还进一步分析了黑潮在吕宋海峡处的涡旋脱落事件,突出强调了LCSs在评估涡旋输运方面的重要性。反气旋涡旋的脱落个例表明,这些涡旋主要源自黑潮“流套”,涡旋脱落之前可有效地俘获黑潮水。LCS所指示的输运通道信息有助于预测最终被反气旋涡所挟卷水体在上游的位置。而在气旋涡的形成过程中,LCS的分布特征表明,大部分气旋涡并未与黑潮水的输运路径相连通。因此,气旋涡对从太平洋到南海的上层水交换的贡献较小。  相似文献   

海上构筑物用海存在的问题及管理政策建议          下载免费PDF全文

李珊  徐伟  刘淑芬 《海洋开发与管理》2020,37(6):108-114

随着社会经济的发展和海洋资源开发利用水平的提高,海上人工构筑物呈现种类、数量和规模都迅速增长的态势。但目前我国大部分海上构筑物尚未纳入统一的管理体系,导致管理权限不清和管理环节缺位。文章分析我国海上构筑物管理的现状和存在的问题,从海洋管理实践出发,对海上构筑物管理进行有益探索,提出在协调众多涉海部门的基础上,从审批、登记、竣工验收、弃置管理、事中事后监管等方面,解决最紧迫的管理需求,先易后难地完善海上构筑物管理的缺位环节,逐步建立和完善海上构筑物管理制度体系,更好地服务于海洋经济建设。  相似文献   

长江经济带城市群要素集聚能力差异的比较研究   总被引：3，自引：2，他引：1  

郭庆宾  骆康  刘承良 《地理科学进展》2020,39(4):542-552

城市群作为当前区域发展的主要空间载体,在区域发展竞争中扮演着越来越重要的角色。论文结合互联网大数据抓取等手段,以长江经济带5个城市群为研究对象,对城市群间要素集聚能力差异进行比较研究,发现：① 长江经济带城市群间要素集聚能力差异与长江经济带社会经济发展的区域差异相吻合,城市群要素集聚格局呈现出由东向西梯度衰减的分布特征;② 城际层面要素集聚能力差异的两极分化现象显著,以城市群首位城市为中心的要素集聚“核心—边缘”空间结构特征较为鲜明;③ 长江经济带城市群内科技创新、对外开放、金融等要素的集聚格局具有明显的差异分化和集聚分布指向特征;④ 长江经济带城市(群)要素集聚能力等级规模结构分布总体符合位序-规模法则,可分为“均衡型”和“离散型”2种类型,首位城市要素集聚首位度随城市群要素集聚能力高低呈现出“两端高、中间低”的特征。  相似文献   

Mitigation of Ice-Induced Vibrations for Offshore Platforms Using Tuned Mass Damper     

张力  岳前进  张文首 《中国海洋工程》2008,22(3):503-511

The problems of ice-induced vibration have been noticed and concerned since the 1960s, but it has not been well resolved. One reason is that the dynamic interaction between ice and structure is so complicated that practical ice force model has not been developed. The recent full-scale tests conducted on jacket platforms in the Bohai Sea presented that ice could cause intense vibrations which endanger the facilities on the deck and make discomfort for the crew. In this paper, the strategy of mitigation of ice-induced offshore structure vibration is discussed. Based on field observations and understanding of the interaction between ice and structure, the absorption mitigation method to suppress ice-induced vibration is presented. The numerical simulations were conducted for a simplified model of platform attached with a Tuned Mass Danlper （TMD） under ice force function and ice force time history. The simulation results show that TMD can fa- vorably reduce ice-induced vibrations, therefore, it can be considered to be an alternative approach to utilize. Finally, the application possibilities of utilizing TMDs on other miniature offshore structures in ice-covered areas of marginal oil fields are discussed.  相似文献   

中国北部得尔布干成矿带构造演化与成矿作用   总被引：11，自引：0，他引：11  

王喜臣  邓军  刘金英  王根厚  田东风 《地球学报》2000,21(3):227-235

得尔布干断裂带控制了火山 侵入杂岩作用 ,形成了多金属成矿带。多期次构造 岩浆活动 ,在成矿带内形成了不同时期规模不等的侵入岩体及大面积分布的中生代火山岩。在区内已发现金、银、铜等多金属矿产地百余处 ,矿床空间分布明显受断裂控制。研究表明 :得尔布干断裂带经历了加里东期到第三纪多期构造演化并伴有相应的岩浆活动。深断裂控制区域构造发展 ,次级断裂对成矿起导矿、容矿作用。本文从构造控矿作用入手 ,分析研究区内各类矿床的构造控矿因素 ,提出了成矿带内多级构造控矿作用 ,对今后在我国东北部找矿有一定的指导意义。  相似文献   

Biological structures as a source of habitat heterogeneity and biodiversity on the deep ocean margins   总被引：1，自引：0，他引：1  

Lene Buhl-Mortensen  Ann Vanreusel  rew J. Gooday  Lisa A. Levin  Imants G. Priede  Pål Buhl-Mortensen  Hendrik Gheerardyn  Nicola J. King  & Maarten Raes 《Marine Ecology》2010,31(1):21-50

Biological structures exert a major influence on species diversity at both local and regional scales on deep continental margins. Some organisms use other species as substrates for attachment, shelter, feeding or parasitism, but there may also be mutual benefits from the association. Here, we highlight the structural attributes and biotic effects of the habitats that corals, sea pens, sponges and xenophyophores offer other organisms. The environmental setting of the biological structures influences their species composition. The importance of benthic species as substrates seems to increase with depth as the complexity of the surrounding geological substrate and food supply decline. There are marked differences in the degree of mutualistic relationships between habitat-forming taxa. This is especially evident for scleractinian corals, which have high numbers of facultative associates (commensals) and few obligate associates (mutualists), and gorgonians, with their few commensals and many obligate associates. Size, flexibility and architectural complexity of the habitat-forming organism are positively related to species diversity for both sessile and mobile species. This is mainly evident for commensal species sharing a facultative relationship with their host. Habitat complexity is enhanced by the architecture of biological structures, as well as by biological interactions. Colony morphology has a great influence on feeding efficiency for suspension feeders. Suspension feeding, habitat-forming organisms modify the environment to optimize their food uptake. This environmental advantage is also passed on to associated filter-feeding species. These effects are poorly understood but represent key points for understanding ecosystems and biodiversity on continental margins. In this paper we explore the contributions of organisms and the biotic structures they create (rather than physical modifications) to habitat heterogeneity and diversity on the deep continental margins.  相似文献   

Effects of two offshore gas platforms on soft-bottom benthic communities (northwestern Adriatic Sea, Italy)     

Sarine Manoukian  Alessandra Spagnolo  Giuseppe Scarcella  Elisa Punzo  Roberta Angelini  Gianna Fabi   《Marine environmental research》2010,70(5):402-410

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Structural evolution of the Orange Basin gravity-driven system,offshore Namibia     

Jose de Vera  Pablo GranadoKen McClay 《Marine and Petroleum Geology》2010

The Orange Basin records the development of the Late Jurassic to present day volcanic-rifted passive margin of Namibia. Regional extension is recorded by a Late Jurassic to Lower Cretaceous Syn-rift Megasequence, which is separated from a Cretaceous to present day post-rift Megasequence by the Late Hauterivian (ca. 130 Ma) break-up unconformity. The Late Cretaceous Post-rift evolution of the basin is characterized by episodic gravitational collapse of the margin. Gravitational collapse is recorded as a series of shale-detached gravity slide systems, consisting of an up-dip extensional domain that is linked to a down-dip zone of contraction domain along a thin basal detachment of Turonian age. The extensional domain is characterized by basinward-dipping listric faults that sole into the basal detachment. The contractional domain consists of landward-dipping listric faults and strongly asymmetric basinward-verging thrust-related folds. Growth stratal patterns suggest that the gravitational collapse of the margin was short-lived, spanning from the Coniacian (ca. 90 Ma) to the Santonian (ca. 83 Ma). Structural restorations of the main gravity-driven system show a lack of balance between up-dip extension (24 km) and down-dip shortening (16 km). Gravity sliding in the Namibian margin is interpreted to have occurred as a series of episodic short-lived gravity sliding between the Cenomanian (ca. 100 Ma) and the Campanian (ca. 80 Ma). Gravity sliding and spreading are interpreted to be the result of episodic cratonic uplift combined with differential thermal subsidence. Sliding may have also been favoured by the presence of an efficient detachment layer in Turonian source rocks.  相似文献   

Seep mounds on the Southern Vøring Plateau (offshore Norway)     

Michael Ivanov  Adriano Mazzini  Valentina Blinova  Elena Kozlova  Jan-Sverre Laberg  Tatiana Matveeva  Marco Taviani  Nikita Kaskov 《Marine and Petroleum Geology》2010

Multidisciplinary study of seep-related structures on Southern Vøring Plateau has been performed during several UNESCO/IOC TTR cruises on R/V Professor Logachev. High-resolution sidescan sonar and subbottom profiler data suggest that most of the studied fluid discharge structures have a positive relief at their central part surrounded by depression. Our data shows that the present day fluid activity is concentrated on the top of these “seep mounds”. Number of high hydrocarbon (HC) gas saturated sediment cores and 5 cores with gas hydrate presence have been recovered from these structures. δ¹³C of methane (between −68 and −94.6‰ VPDB) and dry composition of the gas points to its biogenic origin. The sulfate depletion generally occurs within the upper 30–200 cm bsf and usually coincides with an increase of methane concentration. Pore water δ¹⁸O ranges from 0.29 to 1.14‰ showing an overall gradual increase from bottom water values (δ¹⁸O ∼ 0.35‰). Although no obvious evidence of fluid seepage was observed during the TV surveys, coring data revealed a broad distribution of living Pogonophora and bacterial colonies on sea bottom inside seep structures. These evidences point to ongoing fluid activity (continuous seepage of methane) through these structures. From other side, considerable number and variety of chemosynthetic macro fauna with complete absence of living species suggest that present day level of fluid activity is significantly lower than it was in past. Dead and subfossil fauna recovered from various seep sites consist of solemyid (Acharax sp.), thyasirid and vesicomyid (cf. Calyptogena sp.) bivalves belonging to chemosymbiotic families. Significant variations in δ¹³C (−31.6‰ to −59.2‰) and δ¹⁸O (0.42‰ and 6.4‰) of methane-derived carbonates collected from these structures most probably related to changes in gas composition and bottom water temperature between periods of their precipitation. This led us to ideas that: (1) seep activity on the Southern Vøring Plateau was started with large input of the deep thermogenic gas and gradually decries in time with increasing of biogenic constituent; (2) authigenic carbonate precipitation started at the near normal deep sea environments with bottom water temperature around +5 °C and continues with gradual cooling up to negative temperatures recording at present time.  相似文献