Upwelling Dynamics from Days to Years Using Underwater Gliders

使用水下滑翔机从数天到数年的上升流动力学

• 批准号: 0961999
• 负责人: John Barth
• 金额: $ 90.78万
• 依托单位: Oregon State University
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 2010
• 资助国家: 美国
• 起止时间: 2010-08-01 至 2014-07-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=0961999&HistoricalAwards=false
• 关键词: Upwelling; Dynamics; Days; Years; Using

This project is to analyze a unique space-time data set of continental shelf water properties obtained using autonomous underwater vehicle gliders. Since spring 2006, gliders have been at sea for over 1000 days, sampled over 400 cross-shelf sections, and covered 26,000 km off central Oregon, during a wide range of wind and buoyancy forcing. Glider data are primarily from along the Newport Hydrographic (NH) line, a location representative of regional upwelling processes and for which there is a 50-year data base. Since the gliders sample the upwelling front and jet region in just days, but do so nearly continuously and for multiple years, this analysis seeks to go beyond 2-3 week, ship-based snapshots of coastal upwelling processes and spatially limited moored time series. The PIs will investigate the observed complex water-column structure, in particular subsurface temperature and chlorophyll inversions associated with the coastal upwelling front, and a low-oxygen, near-bottom layer over the mid to inner shelf. Analyses will emphasize the interaction of wind-driven flow and the substantial relative vorticity near the coastal upwelling jet/front in determining the injection of surface water and the material it contains down into the water column. The project will also add Acoustic Doppler Current Profilers to the existing gliders in order to estimate the important ageostrophic secondary circulations. The team will quantify the relative contribution of physical processes (upwelling, horizontal advection, retention, source-water variability) to the structure and longevity of the near-bottom, low-oxygen layer. During 2008, a second E-W glider line south of the NH line and a N-S glider line connecting the two E-W lines were occupied. These concurrent lines will be used to estimate the cross-shelf flux of water and the material it contains as the coastal upwelling jet interacts with a submarine bank. All these analyses will combine glider data with wind measurements and remotely sensed surface data to extend our dynamical understanding of the above shelf processes. The regular glider sampling on the NH line will be continued for two more years (2010-2011) to further understand the substantial interannual variability (El Niño, Pacific Decadal Oscillation) in the northern California Current. Glider data, will be used together with meteorological and satellite data, and numerical models of wind-driven shelf flows, to understand the dynamics and seasonal variability of upwelling as modulated by interannual variability. Intellectual Merit: The long, uninterrupted, high-resolution time series of four years plus two additional years will offer an unprecedented ability to finely characterize and analyze the dynamics of coastal processes, ranging from multi-day wind-driven to interannual time scales. Understanding flow topography interactions and the ageostrophic cross- frontal circulation associated with the upwelling jet are important, because they represent the mechanisms for transporting material across the shelf and from the surface layer to the interior of the ocean. Furthermore, the complex frontal circulation offers a potentially new formation mechanism for the formation of biologically important "thin-layers." Lastly, the multi-year, shelf-to-slope glider data will pinpoint the importance of interannual variations in upwelling source-water variability to local shelf ecosystem dynamics. Broader Impact: Real-time glider observations provide essential in situ data over the shelf and slope to complement remotely sensed surface observations. Application of new glider technology to the study of the coastal ocean has captured the public's imagination and the education and outreach efforts of this team will continue to engage a range of ocean users. The subsurface glider observations are vital for data-assimilative modeling efforts. The subsurface frontal structure, chlorophyll and dissolved oxygen concentrations are of particular interest to other scientists and local fishermen, who are reached via the Oregon Sea Grant program. Finally, this project supports graduate research as well as summer undergraduate internships.

该项目是分析利用自主水下航行器滑翔器获得的大陆架水特性的独特时空数据集。自2006年春季以来，滑翔机已在海上超过1000天，采样超过400个跨大陆架部分，并覆盖了26,000公里的俄勒冈州中部，在广泛的风和浮力迫使。滑翔机数据主要来自沿着纽波特水文（NH）线，一个代表区域上升流过程的位置，有一个50年的数据库。由于滑翔机在短短几天内就对上升流锋和急流区进行了采样，但几乎是连续多年进行的，因此这项分析试图超越2-3周，对沿海上升流过程和空间有限的停泊时间序列进行船基快照。PI将调查所观察到的复杂水柱结构，特别是与沿海涌升锋相关的次表层温度和叶绿素反演，以及中到内陆架上的低氧近底层。分析将强调风驱动的流动和大量的相对涡度附近的沿海涌升急流/前确定注入地表水和它包含的材料到水柱的相互作用。该项目还将在现有的滑翔机上增加声学多普勒海流剖面仪，以估计重要的非地转次级环流。该小组将量化物理过程（上涌、水平平流、滞留、源水变化）对近底低氧层结构和寿命的相对贡献。在2008年，北偏北线以南的第二条东西滑翔机线和连接两条东西滑翔机线的南北滑翔机线被占领。这些并发线将被用来估计跨大陆架通量的水和它所包含的沿海涌升射流与海底银行相互作用的材料。所有这些分析将结合联合收割机滑翔数据与风测量和遥感表面数据，以扩大我们对上述大陆架过程的动态理解。在北半球线上定期进行的滑翔机采样将再持续两年（2010-2011年），以进一步了解北方加州海流的重大年际变化（厄尔尼诺、太平洋十年期振荡）。滑翔机数据将与气象和卫星数据以及风驱动陆架流的数值模型一起使用，以了解受年际变化影响的上升流的动态和季节变化。智力优势：四年加另外两年的长时间、不间断、高分辨率时间序列将提供前所未有的能力，以精细地表征和分析沿海过程的动态，从多日风驱动到年际时间尺度。了解流动地形相互作用和与上升流急流相关的非地转跨锋面环流是重要的，因为它们代表了将物质从表层输送到海洋内部的机制。此外，复杂的锋面环流为重要的生物“薄层”的形成提供了一种潜在的新的形成机制。“最后，多年的，货架到斜坡的滑翔机数据将查明的重要性，年际变化的上升流源水的变化，以当地货架生态系统动态。更广泛的影响：实时滑翔机观测提供了大陆架和陆坡的基本现场数据，以补充遥感地表观测。将新的滑翔机技术应用于沿海海洋的研究，激发了公众的想象力，该小组的教育和宣传工作将继续吸引一系列海洋用户。水下滑翔机观测对于数据同化建模工作至关重要。通过俄勒冈州海洋赠款计划，其他科学家和当地渔民对地下锋结构、叶绿素和溶解氧浓度特别感兴趣。最后，该项目支持研究生研究以及夏季本科生实习。