A Modeling and Data Study of Dissolved Oxygen and pCFC Age Variability in the Thermocline of the Southern Ocean

0525874知识价值最近的观测溶解氧在重复占领的水文部分已经发现增加明显的氧利用率内的温跃层的南印度，南太平洋和澳大利亚南部。这项拟议研究的目标是确定导致南大洋温跃层内溶解氧变化的物理过程或生物过程的可变性的作用，包括亚南极模式和南极中间沃茨。世界海洋环流实验（WOCE）和气候变化和可预测性（CLIVAR）重复水文方案的数据分析将与使用Hallberg等密度模型的可变物理强迫模型模拟相结合。这些研究将包括氯氟烃。在重复测量过程中，CFC的测量是可用的，在pCFC年龄的增加与温跃层内的氧气减少位于同一地点。由于CFC不受生物过程变化的影响，它们的分布意味着物理强迫的变化产生了增加的表观氧利用率。模拟研究将确认南大洋是否也是如此，并将用于确定由于风的变化、表面浮力作用力以及南大洋温跃层和模式沃茨的通风和循环的气体交换而引起的物理作用力变化的相对重要性。对北太平洋的类似研究表明，同一模型再现了从1980年代到1990年代在深层温跃层中观察到的氧气减少。由于模型的保真度，流域范围的结果可用于提供所观察到的变化的背景。在这项工作中，通风的变化已被证明是重要的形成区域附近的水团的问题，而循环的变化更重要的下游。拟议工作的更广泛影响本项目的结果将有助于解释CLIVAR重复水文期间的二氧化碳系统测量。用于确定人为二氧化碳浓度的碳分数方法依赖于稳态环流的假设，然后使用表观氧利用率（AOU）校正非均衡化，并使用pCFC年龄校正海气不平衡。很明显，在计算碳吸收时需要考虑物理强迫的变化。氟氯化碳化学家和物理海洋学家的密切合作应该提供新的见解这一重要问题。此外，将继续与GFDL的建模小组合作，以使他们的建模工作在解释观测结果方面得到支持。该项目还将有助于开发Hallberg等密度模型的地球化学组成部分，并将与GFDL合作向社区提供离线示踪平流代码。两名博士后研究员和一名研究生将在这个跨学科的研究项目中接受培训。共同首席执行官将继续参与支持妇女在物理海洋学方面的工作，通过国家科学基金会和国家自然资源办公室的支持，为该领域的初级妇女建立一个指导网络。

0525874Intellectual MeritRecent observations of dissolved oxygen during repeat occupations of hydrographic sections have found increased apparent oxygen utilization within the thermocline of the South Indian, South Pacific, and south of Australia. The goal of this proposed research is to identify the role of variability in the physical processes or biological processes which result in changes in dissolved oxygen within the Southern Ocean thermocline, including Subantarctic Mode and Antarctic Intermediate Waters. Data analysis of the World Ocean Circulation Experiment (WOCE) and CLImate VARiability and predictability (CLIVAR) Repeat Hydrography Programs will be combined with model simulations with variable physical forcing using the Hallberg Isopycnal Model. Chlorofluorocarbons (CFCs) will be included in these studies. Where CFC measurements are available during repeat measurements, increases in the pCFC ages are co-located with the decreases in oxygen within the thermocline. Since CFCs are not affected by variability in biological processes, their distributions imply that variability in the physical forcing has produced the increased apparent oxygen utilization. The modeling study will confirm whether this is true as well in the southern ocean and will be used to determine the relative importance of the variability in physical forcing due to variability in the winds, surface buoyancy forcing, and gas exchange on the ventilation and circulation of the thermocline and mode waters of the Southern Ocean. Similar studies of the North Pacific have shown that the same model reproduces the observed decreases of oxygen in the deep thermocline from the 1980s to the 1990s. Because of the fidelity of the model, the basin wide results can be used to provide a context for the observed changes. In that work, changes in ventilation have been shown to be important near the formation region of the water mass in question, while circulation changes were more important further downstream. Broader Impacts of Proposed WorkThe results from this project will contribute to the interpretation of the carbon dioxide system measurements during the CLIVAR Repeat Hydrography. The fractional carbon method for determination of the anthropogenic carbon dioxide concentration relies on the assumption of steady state circulation, and then corrects for remineralization using Apparent Oxygen Utilization (AOU) and for air-sea disequilibrium using pCFC ages. It is clear that variability in physical forcing needs to be considered in the calculation of carbon uptake. The close collaboration of a CFC chemist and a physical oceanographer should provide new insight into this important problem. In addition, collaborations with the modeling group at GFDL will be continued to ground their modeling effort in interpretation of observations. The project will also contribute to the development of the biogeochemical component of the Hallberg Isopycncal Model and will make the offline tracer advection code available to the community in collaboration with GFDL. Two post-doctoral fellows and a graduate student will receive training in this interdisciplinary research project. The co-PI will continue to be involved in supporting women in physical oceanography through an effort supported by NSF and ONR to developing a mentoring network for junior women in the field.