Collaborative Research: The Influence of the Mendeleev Ridge and the Chukchi Borderland on the Large-scale Circulation of the Arctic Ocean

合作研究：门捷列夫海岭和楚科奇边境对北冰洋大范围环流的影响

• 批准号: 0118034
• 负责人: James Swift
• 金额: --
• 依托单位: University of California-San Diego Scripps Inst of Oceanography
• 依托单位国家: 美国
• 项目类别: Continuing Grant
• 财政年份: 2002
• 资助国家: 美国
• 起止时间: 2002-01-01 至 2007-12-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=0118034&HistoricalAwards=false
• 关键词: Collaborative; Research; Influence; Mendeleev; Ridge

The most important subsurface Arctic Ocean transport system, a cyclonic (here anticlockwise) boundary current, organized along the continental slopes and major trans-Arctic ridges, distributes waters, tracers and contaminants from the Atlantic (via Fram Strait and the Barents Sea) and the Pacific (via Bering Strait) around and into the deep Arctic basins. On its circum-Arctic pathway, parts of the topographically steered current are diverted away from the continental margin, generally along topographic ridges. The most complex obstacle the boundary current encounters is the Mendeleev Ridge/Chukchi Borderland complex, north of the Pacific entrance to the Arctic. This region is the cross- roads for Pacific-origin waters from the south and Atlantic waters carried from the west with the boundary current. The tortuous bathymetry offers many routes for a topographically steered current, and the spatial variability of the sparse data that exist clearly indicates the complexity of the region. These data also show significant interannual variability, in line with the major changes seen in the last decade throughout the Arctic, and they further suggest that the region diverts significant amounts of water into the deep basins, indicating this region's importance to shelf-basin exchange, deep basin ventilation, and circum- and trans-Arctic circulation (with feedback implications to the World Ocean circulation). Yet, the pathways and exchanges in this area are still unclear, both qualitatively and quantitatively, due to the lack of sufficiently concentrated observations. This research will conduct a high spatial resolution hydrographic and tracer survey, supported by short-term moored current and CTD measurements, in the region of the Chukchi Borderland and the southern end of the Mendeleev Ridge during August/September 2002.The objectives are to:- delineate the pathways of the boundary current carrying the Atlantic water past the Mendeleev Ridge and through the Chukchi Borderland;- ascertain the input from the boundary current and the shelves to the deep Arctic Ocean in the vicinity of the Mendeleev Ridge and the Chukchi Borderland;- understand and quantify the pathways and transformations of the Pacific waters through this region;- describe the horizontal and vertical structure of the boundary current, and estimate its transport; and- quantify recent temporal changes in this region by combining the spatially sparse data extending through most of the past decade with new detailed synoptic measurements.On a 35-day expedition on an ice-breaking research vessel, measurements will be made of temperature, salinity, dissolved oxygen, nutrients, CFCs, Ba, and 18-O on 12 sections that cross both the boundary flow and the Pacific inputs to the region before and after topographic junctions and hypothesized regions of flow diversion. This tracer suite will enable identification of the pathways of the boundary current and the Pacific-origin waters, and quantification of the different Atlantic and Pacific influences, as well as freshwater input from ice melt and different rivers. In addition, three moorings will be deployed, spanning the boundary current for the duration of the cruise. Current meters and moored conductivity and temperature sensors will quantify the vertical and horizontal extent of the boundary current, its structure and variability, and will yield an estimate of the transport and a description of eddies carried with or across the boundary current. To give a comprehensive picture of the system, the entire data set will be analyzed collectively and in tandem with hydrographic, tracer, and moored time series data from the last decade. Since the transit time of signals through this region is 2-4 years, the older data provide a temporal background for the new high spatial resolution data, whilst the newer data will supply an essential spatialframework for understanding the variability of the older surveys.The work will yield a substantially increased understanding of the role of this region in the Arctic circulation, including a determination of pathways, a quantification of exchanges, and an assessment of temporal change. Its timing in 2002 will fill a pending hiatus in hydrographic surveys in the Canadian Basin at a time when the most dramatic changes ever observed in the Arctic are propagating through this region. The project will provide necessary background and mechanistic information to the potential SEARCH and Arctic-Subarctic Ocean Flux programs, and essential far-field information to the SBI Phase II field program in the Chukchi and Beaufort seas. In addition, the results will be pivotal to validating and improving high resolution computer and conceptual models of the Arctic, and will offer insights to physical mechanistic problems, such as the driving mechanism of the boundary current and the interaction of an equivalent barotropic current with steep and sharp topography.

最重要的北冰洋地下输送系统是气旋（这里是逆时针）边界流，沿着大陆坡和主要的跨北极海脊组织，将来自大西洋（通过弗拉姆海峡和巴伦支海）和太平洋（通过白令海峡）的水、示踪剂和污染物分布到北极深海盆地周围并进入​​其中。在其环北极路径上，部分地形引导的洋流通常沿着地形山脊偏离大陆边缘。边界流遇到的最复杂的障碍是门捷列夫海岭/楚科奇边境复合体，位于太平洋北极入口以北。该区域是来自南部的太平洋水域和由边界流从西部带来的大西洋水域的十字路口。曲折的测深为地形引导的水流提供了许多路线，而现有的稀疏数据的空间变化清楚地表明了该地区的复杂性。这些数据还显示出显着的年际变化，与过去十年整个北极地区发生的重大变化一致，并且进一步表明该地区将大量水转移到深盆地，表明该地区对陆架-盆地交换、深盆地通风以及环北极和跨北极环流（对世界海洋环流具有反馈影响）的重要性。然而，由于缺乏足够集中的观察，该领域的途径和交流在定性和定量上仍然不清楚。这项研究将在 2002 年 8 月/9 月期间在楚科奇边境地区和门捷列夫海岭南端进行高空间分辨率水文和示踪调查，并得到短期系泊洋流和 CTD 测量的支持。目的是： - 描绘携带大西洋水流过门捷列夫海岭并穿过楚科奇边境的边界洋流的路径； - 确定来自 门捷列夫海岭和楚科奇边境附近北冰洋深部的边界流和陆架； - 了解和量化太平洋水域通过该地区的路径和转变； - 描述边界流的水平和垂直结构，并估计其输送； - 通过将过去十年大部分时间的空间稀疏数据与新的详细天气测量相结合，量化该地区最近的时间变化。在破冰研究船上为期 35 天的探险中，将在 12 个剖面上测量温度、盐度、溶解氧、营养物、CFC、Ba 和 18-O，这些剖面穿过边界流和太平洋输入到该地区之前和之后 地形交汇处和假设的分流区域。该示踪剂套件将能够识别边界流和太平洋起源水域的路径，量化大西洋和太平洋的不同影响，以及来自冰融化和不同河流的淡水输入。此外，还将部署三个系泊装置，在巡航期间跨越边界流。海流计和系泊电导率和温度传感器将量化边界流的垂直和水平范围、其结构和变化，并将产生传输的估计和对边界流携带或穿过边界流的涡流的描述。为了全面了解该系统，整个数据集将与过去十年的水文、示踪剂和系泊时间序列数据一起进行集体分析。由于信号通过该区域的传输时间为 2-4 年，较旧的数据为新的高空间分辨率数据提供了时间背景，而较新的数据将为了解旧调查的变异性提供必要的空间框架。这项工作将大大加深对该区域在北极环流中的作用的了解，包括路径的确定、交换的量化和时间变化的评估。 2002年的时间安排将填补加拿大盆地水文测量中悬而未决的空白，当时北极地区观测到的最剧烈的变化正在该地区蔓延。该项目将为潜在的 SEARCH 和北极-亚北极洋通量项目提供必要的背景和机制信息，并为 SBI 第二阶段楚科奇海和波弗特海实地项目提供必要的远场信息。此外，这些结果对于验证和改进北极的高分辨率计算机和概念模型至关重要，并将为物理机制问题提供见解，例如边界流的驱动机制以及等效正压流与陡峭地形的相互作用。