Collaborative research: Constraining the global ocean nitrogen cycle with multiple tracers in a biogeochemical inverse model

海洋环境中的氮(N)生物地球化学循环受到复杂的生物和环境反馈，具有未知的气候敏感性。过去的研究试图利用生物地球化学示踪剂（如营养化学计量学、氮同位素和N2气体）来表征海洋氮库存，但这些研究都是一个快照，一次只关注海洋特定区域的单一过程。这些研究被迫忽略了其他重要和相关的控制机制。为了解决影响N库存的过程的环境控制的大小和类型，需要同时考虑过程。来自加州大学洛杉矶分校的研究人员建议对主要氮收支通量的空间分布和速率进行建模。为了得出全球海洋氮预算，研究人员建议使用与所有可用示踪剂数据一致的逆模型框架。全球海洋环流模型将包含示踪剂的生物地球化学循环，并将被约束以优化对物理示踪剂（T， S, 14-C-age, CFCs）的拟合。为了检验环境变量如何影响每一通量的大小，将根据模拟结果对它们进行回归，从而深入了解预期的气候变化对氮收支的影响。此外，对逆解的误差结构的分析将使研究人员能够检查与示踪剂相关的假设的有效性。这项工作可以建立一个严格的统计框架，使研究人员能够吸收快速发展的数据流，并将突出海洋中缺乏数据的区域，从而使资源得到战略性的利用。该项目将为本科生和研究生以及博士后提供教育和培训，并将为了解气候变化对海洋过程的影响所必需的氮的生物地球化学循环提供重要信息和见解。

Nitrogen (N) biogeochemical cycling in the marine environment is subject to complex biological and environmental feedbacks with unknown climate sensitivities. Past studies have attempted to characterize the marine N inventory using biogeochemical tracers, such as nutrient stoichiometry, nitrogen isotopes and N2 gas, but these studies have been a snapshot, focusing on a single process in a specific region of the ocean at a time. Such studies were forced to ignore other important and related controlling mechanisms. To resolve the magnitude and type of environmental controls on the processes that influence the N inventory, processes need to be considered simultaneously. Researchers from the University of California at Los Angeles propose to model the spatial distributions and rates of the primary N budget fluxes. In order to derive a global marine N budget, researchers propose to use an inverse model framework that is consistent with all available tracer data. The global ocean circulation model will contain biogeochemical cycles of tracers and will be constrained to optimize the fit to physical tracers (T, S, 14-C-age, CFCs). To examine how environmental variables affect the magnitude of each flux, they will be regressed against the modeling results, providing insight into the effects of anticipated climate change on the N budget. Furthermore, analysis of the inverse solution's error structure will allow researchers to examine the validity of tracer-related assumptions. This work could set up a statistically rigorous framework that will enable researchers to assimilate rapidly developing data streams and will highlight areas in the oceans where data is lacking, allowing resources to be used strategically. The project will provide education and training for undergraduate and graduate students, as well as a post-doc, and will provide important information and insights into the biogeochemical cycling of N necessary to understand the impact of changing climate on ocean processes.