Collaborative Research: "EaSM-3": The Role of Ocean Eddies in Decadal Prediction

对环境预测的需求日益增长，其中包括更广泛的空间和时间尺度，以及更完整地表示天气和气候过程。满足这一需求需要一种统一的方法来挑战天气和气候科学之间的传统界限，并且需要一种更加综合的方法和更高的空间分辨率模型来解决重要的动力学过程及其相互作用。可预测性的估计可能对这些模型捕获的过程和现象的范围敏感。该项目旨在对海洋涡流如何影响年代际可预测性进行全面评估。该项目提出的关键问题之一是，预测系统实际上需要初始化各个海洋涡流，还是仅仅将海洋涡流包含在预测系统中就足够了？回答这个问题对于十年预测系统的设计具有深远的影响。该项目将通过对研究生进行重要的气候变率和变化问题的教育以及对博士后研究员的指导来促进劳动力发展。将向年代际预测和气候服务界提供关于海洋涡流如何影响年代际可预测性以及如何在涡流解析模型中初始化它们的建议。可免费访问的社区地球系统模型 (CESM) 和数据同化研究测试台 (DART) 建模框架中的高分辨率同化新功能将可供 CESM 气候建模社区使用。更广泛地说，任何与 DART 集成同化系统接口的模型都可以利用该项目下将开发的数据同化基础设施进步和工具开发。 更广泛的气候界感兴趣的海洋涡旋解析模拟、数据同化产品、可预测性和实验预测结果也将随时可用。该研究项目基于这样的假设：与海洋涡旋相关的动态和物理过程以及伴随的与大气的相互作用对年代际可预测性具有巨大而强大的影响。拟议的研究旨在通过分析长涡旋解析模拟和预后“完美”模型可预测性实验，通过诊断可预测性研究来量化这种效应。将开发以涡流解析分辨率初始化耦合模型的海洋部分所需的工具和功能。新的涡旋分辨数据同化系统将通过实验预测进行评估。该项目还寻求开发一个适合在海洋涡旋分辨尺度上初始化年代际预测的数据同化系统。当前在允许涡流分辨率下可用的基于集合的海洋数据同化方法将应用于涡流分辨模型。为了支持调整新的高分辨率数据同化系统，将开发用于估计同化中使用的分辨率相关观测误差统计的新工具。与分辨率相关的观测误差统计的规范对于数据同化来说非常重要，并且目前还没有支持这一点的工具。高分辨率海洋数据同化系统的局限性将根据其计算成本及其约束涡流场的功效进行评估，该项目将制定解决这些局限性的策略，这些策略与十年预测的需求相一致，被确定为十年可预测性研究的一部分。最后，数据同化系统将在2006年至今数据丰富的年份在涡旋分辨尺度上实施，并通过实验预测进行评估。

There is a growing demand for environmental predictions that include a broader range of space and time scales and that include a more complete representation of weather and climate processes. Meeting this demand necessitates a unified approach that challenges the traditional boundaries between weather and climate science, and requires a more integrated approach with much higher spatial resolution models that resolve important dynamical processes and their interactions. Estimates of predictability are likely to be sensitive to the range of processes and phenomena captured by these models. This project seeks to provide a comprehensive assessment of how ocean eddies affect decadal predictability. One of the key questions this project asks is, do prediction systems actually need to initialize individual ocean eddies or is simply including ocean eddies in the prediction system sufficient? Answering this question has profound implications in the design of decadal prediction systems. This project will contribute to workforce development through the education of a graduate student in important climate variability and change problems, and the mentoring of a post-doctoral researcher. The decadal prediction and climate services community will be advised regarding how ocean eddies impact decadal predictability and how to initialize them in eddy resolving models. The new capacity for high-resolution assimilation within the freely accessible Community Earth System Model (CESM) and Data Assimilation Research Testbed (DART) modeling frameworks will be available to the CESM climate modeling community. More broadly, any model that interfaces with the DART ensemble assimilation system can leverage the data assimilation infrastructure advances and tool development that will be developed under this project. Ocean eddy-resolving simulations, data assimilation products, predictability and experimental prediction results that are of interest to the broader climate community will be also made readily available.This research project is based on the hypothesis that the dynamic and physical process associated with ocean eddies and the accompanying interactions with the atmosphere have a large and robust impact on decadal predictability. The proposed research seeks to quantify this effect through diagnostic predictability research by analyzing long eddy resolving simulations and prognostic "perfect" model predictability experiments. Tools and capabilities that are necessary to initialize the ocean component of coupled models at eddy resolving resolutions will be developed. The new eddy resolving data assimilation system will be evaluated through experimental prediction. The project also seeks to develop a data assimilation system appropriate for initializing decadal prediction at ocean eddy-resolving scales. The current ensemble-based ocean data assimilation method available at eddy-permitting resolution will be applied to the eddy-resolving model. To support tuning the new high-resolution data assimilation system, novel tools for estimating the resolution-dependent observational error statistics used in the assimilation will be developed. The specification of resolution-dependent observational error statistics is of enormous importance for data assimilation, and tools to support this are currently unavailable. The limitations of the high-resolution ocean data assimilation system will be assessed in terms of its computational cost and its efficacy at constraining the eddy field, and the project will develop strategies for addressing these limitations that are aligned with the needs of decadal prediction that are identified as part of the decadal predictability research. Finally, the data assimilation system will be implemented at eddy-resolving scales during the data-rich years of 2006-present, and evaluated with experimental predictions.