EaSM-3: Collaborative Research: Quantifying Predictability Limits, Uncertainties, Mechanisms, and Regional Impacts of Pacific Decadal Climate Variability

太平洋地区的气候在年代际尺度上发生变化，但控制这些长期气候变化的机制仍不清楚。如果能更好地理解这些机制，那么在这些时间尺度上进行气候预测的不确定性就能得到更准确的评估。由于太平洋对美国西部的下游影响及其对阿拉斯加气候的直接影响，美国对太平洋的年代际变化特别感兴趣。本项目利用一系列气候模式和现代统计工具，解决了太平洋气候系统年代际模态的可预测性限制、机制和区域影响等基本问题。该项目的结果对于评估环境的长期变化如何驱动经济上重要变量的变化非常重要，这些变量包括降雨、土壤湿度、降雪、温度、海洋温度、洋流和海平面，这些变量影响美国西海岸和亚洲边缘海的渔业、农业和沿海基础设施。本项目开发的工具应可转让给同样表现出年代际变化的其他全球部门。项目团队将指导研究生和博士后，他们的教育经历将包括跨学科的海洋科学、大气科学和在此背景下独特的社会影响。社区外展将包括在公共论坛上进行讲座和教育演讲，指导K-12学生，教育基层气候行动组织，向媒体通报情况，并在网页上发布研究结果。在控制太平洋年代际气候变化的因素，限制洋流可预测性的因素，以及哪些实用技能可能对陆地和海洋的区域影响有用等方面，我们的理解显然存在很大差距。项目小组提出了一项协调的研究工作，以更好地了解太平洋年代际变率的基本物理动态，并评估太平洋年代际可预测性的技能及其不确定性和实用价值。该研究的重点是社区地球系统模型（CESM），其庞大的存档运行库补充了有针对性的可预测性实验。分析的重点是使用复杂的统计模型（线性逆模型）来识别变量之间的统计关系，诊断物理过程，并隔离流的潜在可预测成分。它还涉及使用区域大气-海洋耦合以及非耦合的海洋和大气模式，以加强对区域反应的了解及其在预报中实际应用的潜力。该项目汇集了擅长发展年代际气候诊断、进行统计和动态预测、执行区域耦合气候降尺度和区域高分辨率海洋模型的科学家。

Climate in the Pacific region varies on decadal timescales, but the mechanisms that control these long-term climate variations are still unclear. If the mechanisms can be better understood, then the uncertainties associated with making climate predictions on these timescales can be assessed more accurately. Decadal variability over the Pacific is of particular interest in the United States due to its downstream influence over the western United States and its direct influence on climate in Alaska. This project addresses the fundamental question of what are the predictability limits, mechanisms, and regional impacts for decadal modes of the Pacific climate system using a hierarchy of climate models and modern statistical tools. The results of this project will be important in assessing how long-term changes in the environment drive changes in economically important variables such as rainfall, soil moisture, snowfall, temperatures, as well as oceanic temperatures, currents and sea levels, which impacts fisheries, agriculture, and coastal infrastructure along the U.S. West Coast and Asian Marginal Seas. The tools developed in this project should be transferable to other global sectors that also exhibit decadal variability. The project team will mentor graduate students and post-docs, whose educational experiences will include cross-disciplinary exposure to ocean science, atmospheric science, and societal impacts that will be unique in this context. Community outreach will include lectures and educational presentations in public forums, mentoring K-12 students, educating grass-roots climate action organizations, informing the media, and posting research results on web pages.There is clearly a large gap in our understanding of what controls Pacific decadal climate variability, what limits the predictability of the flows, and what practical skill might be useful in regional impacts on land and in the ocean. The project team proposes a coordinated research effort to better understand the basic physical dynamics of Pacific decadal variability and assess the skill of Pacific decadal predictability, along with its uncertainties and practical value. The research focuses on Community Earth System Model (CESM), with its vast repository of archived runs supplemented with targeted predictability experiments. The analysis focuses on using sophisticated statistical models (Linear Inverse Models) to identify statistical relations among variables, diagnose physical processes, and isolate potentially predictable components of the flows. It also involves using regional coupled atmosphere-ocean, along with uncoupled ocean and atmosphere models, to enhance the understanding of regional response and its potential for practical use in forecasting. The project brings together scientists skilled with developing decadal climate diagnostics, making both statistical and dynamical predictions, and executing regional coupled climate downscaling and regional high-resolution ocean modeling.