Collaborative research: Understanding the spatial and temporal variability of dissolved oxygen through a hierarchy of models.

在这个项目中，加州大学洛杉矶分校和科罗拉多州立大学的海洋模型师将开发一个新的理论框架，以了解和预测海洋氧对大范围气候变化的响应。最近对上层海洋中氧的年代际变化的观察--现在每个海洋盆地都有记录--引发了关于潜在机制的几个问题。在不同的时间尺度上，溶解氧对大气强迫有何反应？时间谱和空间模式与物理和生物驱动力的时间谱和空间模式以及它们之间的耦合有什么关系？对长期趋势和流域尺度变化的模拟研究表明，溶解氧对物理和生物过程都高度敏感，已被建议作为海洋气候变化的示踪剂。然而，对潜在原因的机制理解还远未完成，因此需要更全面地阐明氧气变化的大规模模式，特别是在新数据迅速增加的情况下。研究小组假设，氧气变化的物理和生物驱动因素受到上层海洋温跃层通风的调节，导致大范围、低频率的变化增强。这一理论为解释两个反复出现的普遍观测提供了新的假说：O2的变化在十年时间尺度上非常普遍，并集中在水柱中占据一个共同位置的水域，即通风温跃层的底部。他们计划使用一系列模型来评估这些预测，模型的范围从一维等周期模型到具有生态系统和生物地球化学成分的最先进的允许涡流的全球海洋模型。工作计划将包括比较一系列模型的模式，阐明海洋氧气循环的基本和非模型依赖的动力学。该项目最终将我们的理论和建模方法应用于观测系统模拟实验(OSSES)，以拟议的Argo-O2项目的全球实施，以制定未来的观测战略。这将是朝着建立一套工具的方向迈出的重要一步，该工具用于理解在现实世界中发现的O2变化的类型，并为分析这一重要示踪剂的广泛观测和建模数据奠定基础。更广泛的影响：研究人员预计，这项工作将阐明缺氧是海洋中一个新出现的问题，对渔业管理者和海洋保护工作具有战略意义。通过拟议的全球海洋观测系统，该项目将协助制定最佳观测战略，以便国际社会努力在阿尔戈浮标上建立全球氧气传感器阵列。预计这些结果还将为估计这种不规则采样网络造成的全球范围的O2损失提供一个机制基础，从而减少在量化陆地和海洋之间人为二氧化碳吸收分配方面的一个关键不确定性。最后，该项目将为两名初级研究生提供培训和支助，并在科罗拉多州立大学为K-12至研究生和普通公众举办海洋和气候科学外联活动。

Abstract In this project ocean modelers at The University of California at Los Angeles and Colorado State University will develop a new theoretical framework for understanding and predicting the responses of oceanic oxygen to wide range of climate variability. Recent observations of decadal oxygen changes of in the upper ocean, which now have been documented in every ocean basin, motivate several questions regarding the underlying mechanisms. How does dissolved oxygen respond to atmospheric forcing at different time scales? How do the temporal spectrum and spatial patterns relate to that of its driving forces, both physical and biological, and to the coupling between them? Modeling studies on long-term trends and basin-scale variability revealed that dissolved oxygen is highly sensitive to both physical and biological processes, and it has been suggested as a tracer of climate change in the oceans. However, mechanistic understanding of underlying causes are far from complete, and fuller elucidation of the large-scale modes of oxygen variability is therefore needed, particularly as new data is rapidly increasing. The research team hypothesizes that the physical and biological drivers of oxygen changes are modulated by the thermocline ventilation in the upper ocean, leading to enhanced large-scale, low frequency variability. The theory leads to novel hypotheses for explaining two recurring and general observations: that O2 changes are so prevalent at decadal time scales and are focused in waters occupying a common position in the water column, namely the base of the ventilated thermocline. They plan to evaluate these predictions using a hierarchy of models ranging from a one-dimensional isopycnal model to a state-of-the-art eddy-permitting global ocean model with ecosystem and biogeochemistry components. The work plan will involve comparison of patterns across a hierarchy of models, illuminating fundamental and non-model dependent dynamics of the oceanic oxygen cycle. This project culminates in the application of our theoretical and modeling approach to the Observing System Simulation Experiments (OSSEs) for the proposed global implementation of ARGO-O2 project to develop future observational strategies. This will be a major step toward building a set of tools for understanding the types of O2 variability found in the real world, and laying the groundwork for analyzing a wide range of observational and modeling data for this important tracer. Broader Impacts: The researchers anticipate that this work will shed light on hypoxia as an emerging problem in the ocean of strategic importance to fisheries managers and marine conservation efforts. Through the proposed OSSEs, this project will assist in the formulation of optimal observational strategies for the international efforts to develop the global array of O2 sensors on ARGO floats. The results are also expected to provide a mechanistic basis for estimating global scale losses of O2 from such irregular sampling networks, thus reducing a key uncertainty in the quantification of the partitioning of anthropogenic CO2 uptake between the land and the oceans. Finally, the project will provide for the training and support of two beginning graduate students, as well as outreach activities at Coloado Statue University on oceans and climate science for K-12 through graduate students and for the general public.