Physical Control of Carbon Export in the Subarctic Pacific

智力优势：物理和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海洋表层初级生产产生的有机碳的命运。尽管碳输出对全球CO2浓度有着深刻的控制作用。由于海洋的大气层中存在大量的碳，因此，对生产率的现场测量与从全球年平均值推断的结果并不完全一致，各种海洋环境中碳输出的可变性范围也尚未完全确定。一个流行的方法来评估海洋代谢是制定一个氧气质量平衡，其中的氧预算是在混合层或真光区，物理过程的影响被删除，和剩余的氧气生产是化学计量有关的碳出口到深度。虽然基于船舶的氧气质量平衡研究在很大程度上受到费用和资源的可用性的阻碍，最近的努力，使用远程测量的氧气从停泊的传感器显示出相当大的潜力，具有成本效益和地理上广泛的诊断的生物泵。这些技术已扩展到移动的自主平台，如阿尔戈浮标和海洋滑翔机剖面图，提供了控制初级生产的主要物理过程的增强的、高分辨率的垂直和水平图像。该项目将对具有前所未有的持续时间和分辨率的遥感时间序列进行全面的物理和氧气质量平衡评估：华盛顿大学海洋滑翔机海洋站P时间序列在阿拉斯加湾南部。2008年6月至2010年1月，三个独立的海底滑翔机部署在装备齐全的美国国家海洋和大气管理局太平洋海洋环境实验室（NOAA/PMEL）P站系泊系统上，收集了基本物理特性、生物光学变量和溶解氧的详细垂直和水平剖面。在这段时间的延长部分，P站系泊观测大气变量和相应的物理参数内的近表层海洋，这些数据集一起代表了一个强大的工具，增加到建立的物理变化和净氧生产在中部亚北极太平洋的图片。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diapycnal混合过程，因为它们适用于活性示踪剂的预算; 2）在时间序列过程中获得混合层中净氧产生的稳健估计; 3）评估呼吸（4）估算密度跃层以下呼吸与深度的依赖关系。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基础，并增加在碳出口背景下分析的时间序列的长度。更好地了解平流在表层将允许比较以前的残差估计这一项及其相对重要性在每个阶段的季节性周期。探索在时间和深度的diapycnal扩散率的依赖性将提高和澄清我们的知识，它的作用，在P站的氧气垂直运输。此外，分析相结合的停泊和自主车辆的时间序列应该提供一个基础的技术，用于类似的未来部署在世界海洋难以观察的地区。

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.