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

对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的环境预测的需求日益增长。为了满足这一需求，需要一种统一的方法，挑战天气和气候科学之间的传统界限，并需要一种更综合的方法，采用更高空间分辨率的模型来解决重要的动力过程及其相互作用。对可预测性的估计可能对这些模型所捕获的过程和现象的范围很敏感。该项目旨在全面评估海洋涡旋如何影响年代际可预测性。这个项目提出的一个关键问题是，预测系统是否真的需要初始化单个海洋涡流，还是仅仅在预测系统中包含海洋涡流就足够了？回答这个问题对年代际预测系统的设计具有深远的意义。该项目将通过对一名研究生进行重要气候变率和变化问题的教育，以及对一名博士后研究员的指导，为劳动力发展做出贡献。将向年代际预测和气候服务界提供关于海洋涡旋如何影响年代际可预测性以及如何在涡旋解析模式中初始化它们的建议。在免费获取的社区地球系统模型（CESM）和数据同化研究试验台（DART）建模框架内，高分辨率同化的新能力将提供给CESM气候建模社区。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数据同化基础设施的进步和将在该项目下开发的工具开发。海洋涡旋解析模拟、数据同化产品、可预见性和实验预测结果，这些都是广大气候学界感兴趣的。这个研究项目是基于这样一个假设，即与海洋涡旋有关的动力和物理过程及其伴随的与大气的相互作用对年代际可预测性有很大而有力的影响。拟议的研究旨在通过分析长涡解析模拟和预测“完美”模式可预测性实验，通过诊断可预测性研究来量化这种影响。将开发以涡分辨率初始化耦合模式的海洋分量所必需的工具和能力。本文将通过实验预报对新的涡解析同化系统进行评价。该项目还寻求发展一种数据同化系统，适于在海洋涡旋解析尺度上初步进行年代际预测。目前在允许涡旋分辨率下可用的基于集合的海洋资料同化方法将应用于涡旋分辨率模式。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。依赖于分辨率的观测误差统计的规范对于数据同化非常重要，而支持这一点的工具目前还不可用。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在限制涡场方面的有效性进行评估，该项目将制定战略，以解决这些局限性，这些局限性与十年预测的需要相一致，这些需要已被确定为十年可预测性研究的一部分。最后，在数据丰富的2006年至今，数据同化系统将在涡旋解析尺度上实施，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.