Estimating and Analyzing the Southern Ocean State

这个项目的主要目的是对2005年1月至2009年12月期间南大洋的状况进行评估。结果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，使其对跨越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（即不会实施非物理的推动或放松项），因此是量化循环和研究动态平衡的合理工具。为了回答以下两个问题，本文将利用南大洋状态估计来分析体积和潜在涡量（PV）预算。南大洋中什么地方有明显的潜流混合？什么是三维位涡（PV）预算？体积预算分析涉及到等共轴空间连续性方程的诊断。本预算中的项将揭示输送路径（通过沿等环流厚度平流项）、浮力预算（通过海气通量源项）、深海混合（通过深环流输送项）和PV预算（通过厚度趋势项）。这四种现象都值得研究，但为了与所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。河床混合率图将突出显示海洋湍流和水团演化增加的区域。本地过程研究将提供有关拟议工作中的不确定性的信息，而我们的结果将把本地过程研究放在更大的背景下。在等平空间中绘制PV分布将揭示水团输送途径，而分析PV收支将阐明这些途径的动力学。该项目旨在将目前对南大洋光伏预算的垂直整合理解演变为三维空间。通过涡旋伸展的PV交换被认为是南极环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密度水平之间的分区。与国际极地年（IPY）项目开展更广泛的影响合作将加强该项目。同样，向科学界提供南大洋状态评估将为许多其他资助项目增加价值。例如，在南大洋项目示踪剂释放观测中使用深环流和等环流混合实验将使该项目受益，因为它更好地约束了估计，也允许确定参考示踪剂扩散系数。作为回报，状态估计将为DIMES项目的研究人员提供一个受约束的背景状态，供他们进行分析。确定准确的背景平均状态对于DIMES项目确定局部地轴和等轴混合的目标至关重要。将稀疏而独特的观测结果综合成一个允许涡旋状态的估计，是加深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.