Estimating and Analyzing the Southern Ocean State

本项目的中心目的是对2005年1月至2009年12月期间南大洋的状况作出估计。由此产生的估计将比以前的解决方案更符合观测结果，并且还将包括IPY时间段，使其对跨多个学科的许多研究人员有用。时变的、允许涡流的估计将是动态现实的（即，将不实施非物理的轻推或松弛项），并且因此是用于量化环流和调查动态平衡的合理工具。使用南大洋状态估计的体积和位涡（PV）的预算将进行分析，以回答以下两个问题。在南大洋，什么地方的底流混合是显著的？什么是三维位涡（PV）收支？体积收支分析涉及等密度空间中的连续性方程的诊断。本预算中的条款将揭示运输途径（通过沿等密度厚度平流项），浮力预算（通过海气通量源项），深海混合（通过底辟运输项），和PV预算（通过厚度趋势项）。所有这四种现象都值得研究，尽管为了与提出的科学问题保持一致，分析将主要集中在后两个术语上。纵贯混合率的地图将突出显示海洋湍流和水团演变增加的区域。当地的过程研究将提供有关拟议工作中的不确定性的信息，而我们的研究结果将把localprocess研究在一个更大的背景下。绘制等密度空间中的PV分布图将揭示水质量传输路径，分析PV预算将阐明这些路径的动态。该项目旨在将目前对南大洋光伏预算的垂直综合理解发展为三维。通过涡旋拉伸的PV交换被认为是南极绕极流系统通过洋脊并维持其大规模纬向输送的机制。该项目的一个关键目标是确定这种拉伸在密度水平之间的划分。与国际极地年（IPY）计划的更广泛影响合作将加强这一项目。同样，向科学界提供南大洋状态估计将增加许多其他资助项目的价值。例如，在南大洋项目中使用纵摇和等密度混合实验的示踪剂释放观测结果将有利于该项目，因为它能更好地限制估计数，而且还能允许 参考示踪剂扩散率的测定。作为回报，状态估计将为DIMES计划中的研究人员提供用于其分析的受约束的背景状态。确定一个准确的背景平均状态是至关重要的DIMES项目的目标，确定当地的diapycnal和等密度线混合。将稀疏和不同的观测结果合成为涡流允许状态估计值，是增进对南大洋了解的一个重要资源。

Intellectual Merit The central purpose of this project is to attain an estimate of the state of the Southern Ocean from January 2005 through December 2009. The resulting estimate will be more consistent with observations than the previous solution, and will also include the IPY time period, making it useful to many researchers spanning multiple disciplines. The time-varying, eddy-permitting estimate will be dynamically realistic (i.e. no unphysical nudging or relaxation terms will be implemented), and thus a justifiable tool for quantifying the circulation and investigating dynamical balances. Using the Southern Ocean state estimate the volume and potential vorticity (PV) budgets will be analyzed in order to answer the following two questions. Where is diapycnal mixing significant in the Southern Ocean? What is the three-dimensional potential vorticity (PV) budget? The volume budget analysis involves diagnosing the continuity equation in isopycnal space. Terms in this budget will reveal transport pathways (via the along-isopycnal thickness advection terms), the buoyancy budget (via the air-sea flux source term), abyssal mixing (via the diapycnal transport term), and the PV budget (via the thickness tendency term). All four phenomena are worthy of investigation, though in keeping with the science questions posed, the analysis will primarily focus on the latter two terms. Maps of the diapycnal mixing rate will highlight regions of increased ocean turbulence and water mass evolution. Local process studies will provide information regarding uncertainty in the proposed work, while our results will put the localprocess studies in a larger context. Mapping the PV distribution in isopycnal space will shed light on water mass transport pathways, and analyzing the PV budget will illuminate the dynamics of these pathways. This project intends to evolve the present vertically-integrated understanding of the Southern Ocean PV budget into three-dimensions. PV exchange through vortex stretching is believed to be the mechanism allowing the Antarctic Circumpolar Current system to pass over ocean-ridges and maintain its massive zonal transport. A key goal of the project is to determine the partitioning of this stretching amongst density levels.Broader Impact Collaboration with International Polar Year (IPY) programs will enhance this project. Likewise, making a Southern Ocean state estimate available to the scientific community will add value to many other funded projects. For example, use of the Diapycnal and Isopycnal Mixing Experiment in the Southern Ocean project tracer release observations will benefit this project by better constraining the estimate, and also by allowing the determination of a reference tracer diffusivity. In return, the state estimate will provide researchers in the DIMES program with a constrained background state for their analysis. Determination of an accurate background mean state is vital to the DIMES project goal of determining local diapycnal and isopycnal mixing. Synthesizing sparse and distinct observations into an eddy permitting state estimate is a great resource for growing understanding of the Southern Ocean.