Physical Control of Carbon Export in the Subarctic Pacific

亚北极太平洋碳输出的物理控制

• 批准号: 1129090
• 负责人: Charles Eriksen
• 金额: $ 32.36万
• 依托单位: University of Washington
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 2011
• 资助国家: 美国
• 起止时间: 2011-09-15 至 2014-08-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=1129090&HistoricalAwards=false
• 关键词: Physical; Control; Carbon; Export; Subarctic

Intellectual Merit: One of the largest outstanding and ongoing research problems in the physical and biogeochemical oceanographic community concerns the fate of organic carbon generated from primary production in the surface ocean. Though carbon export exerts a profound control on CO2 concentrations in the world?s atmosphere, in-situ measurements of production rates are not fully reconciled with those inferred from the global annual average, and the spectrum of variability of carbon export in a variety of oceanic environments has yet to be fully determined. A popular method for evaluating ocean metabolism is the formulation of an oxygen mass balance, in which an oxygen budget is constructed in the mixed layer or euphotic zone, the effects of physical processes are removed, and the residual oxygen production is stoichiometrically related to the export of carbon to depth. While ship-based oxygen mass balance studies are hindered largely by expense and the availability of resources, recent efforts using remote measurement of oxygen from moored sensors display considerable potential for cost-effective and geographically widespread diagnostics of the biological pump. These techniques have been expanded to mobile autonomous platforms such as profiling Argo floats and ocean gliders, which offer an enhanced, highly-resolved vertical and horizontal picture of major physical processes controlling primary production.Continuing the evolution of studies of net biological oxygen production from autonomous platforms, the project will apply a comprehensive physical and oxygen mass balance assessment to a remote-sensing time series of unprecedented duration and resolution: the University of Washington Seaglider Ocean Station P time series in the southern Gulf of Alaska. Three separate Seaglider deployments orbited the well-instrumented National Oceanic and Atmospheric administration Pacific Marine Environmental Laboratory (NOAA/PMEL) Station P mooring from June 2008 to January 2010, collecting detailed vertical and horizontal profiles of basic physical properties, bio-optical variables, and dissolved oxygen. During extended portions of this time, the Station P mooring observed atmospheric variables and corresponding physical parameters within the near surface ocean; taken together these datasets represent a powerful tool for adding to the established picture of physical variability and net oxygen production in the central subarctic Pacific Ocean. In the course of our proposed analysis, we hope to: 1) better constrain horizontal advection, vertical advection, and diapycnal mixing processes, as they apply to the budget of an active tracer; 2) obtain a robust estimate of net oxygen production in the mixed layer during the course of the time series; 3) evaluate respiration (oxygen consumption) below the mixed layer and above the permanent halocline; and 4) estimate the dependence with depth of respiration below the pycnocline. Broader Impacts: This project will expand the knowledge base of the physical dynamics controlling the biological pump in the Gulf of Alaska as well as add to the length of the time series which has been analyzed in a carbon export context. A better understanding of advection in the surface layer would allow comparison to previous residual estimates of this term and its relative importance at each phase of the seasonal cycle. Exploring the dependence in time and depth of diapycnal diffusivity would improve and clarify our knowledge of its role in vertical transport of oxygen at Station P. Additionally, analysis of a combined moored and autonomous vehicle time series should provide a foundation of techniques to be used in similar future deployments in difficult-to-observe regions of the world ocean.

智力价值：物理和生物地球化学海洋学界最大的突出和正在进行的研究问题之一涉及表层海洋初级生产中产生的有机碳的命运。尽管碳输出对世界大气中的二氧化碳浓度具有深远的控制作用，但现场的生产率测量结果与根据全球年平均水平以及各种海洋碳输出的变化范围推断的结果并不完全一致。环境尚未完全确定。评估海洋代谢的一种流行方法是制定氧气质量平衡，其中在混合层或亮光区构建氧气收支，消除物理过程的影响，并且剩余氧气产量与出口按化学计量相关。碳的深度。虽然船基氧气质量平衡研究在很大程度上受到费用和资源可用性的阻碍，但最近使用系泊传感器远程测量氧气的努力显示了生物泵具有成本效益和地理广泛诊断的巨大潜力。这些技术已扩展到移动自主平台，例如分析 Argo 浮标和海洋滑翔机，这些平台提供了控制初级生产的主要物理过程的增强的高分辨率垂直和水平图像。自主净生物氧气生产研究的不断发展平台上，该项目将对持续时间和分辨率前所未有的遥感时间序列应用全面的物理和氧气质量平衡评估：阿拉斯加湾南部的华盛顿大学Seaglider海洋站P时间序列。 2008 年 6 月至 2010 年 1 月，三个独立的 Seaglider 部署绕着装备精良的国家海洋和大气管理局太平洋海洋环境实验室 (NOAA/PMEL) P 站系泊设备运行，收集了基本物理特性、生物光学变量和溶解氧。在这段时间的较长时间内，P 站系泊装置观测了近海表层海洋内的大气变量和相应的物理参数；总的来说，这些数据集是一个强大的工具，可以补充亚北极中部太平洋物理变化和净氧气生产的既定图景。在我们提出的分析过程中，我们希望：1）更好地约束水平平流、垂直平流和间流混合过程，因为它们适用于主动示踪剂的预算； 2) 获得时间序列过程中混合层净氧产量的稳健估计； 3）评估混合层以下和永久盐跃层以上的呼吸（耗氧量）； 4) 估计与碧萝斜线以下呼吸深度的相关性。更广泛的影响：该项目将扩大控制阿拉斯加湾生物泵的物理动力学的知识库，并增加在碳出口背景下分析的时间序列的长度。对表层平流的更好理解将允许与该术语的先前残差估计及其在季节周期每个阶段的相对重要性进行比较。探索二密扩散率对时间和深度的依赖性将提高和澄清我们对其在 P 站氧气垂直输送中的作用的认识。此外，对系泊和自主车辆组合时间序列的分析应该为用于以下方面的技术奠定基础：未来将在世界海洋难以观测的区域进行类似的部署。