Collaborative Research: P2C2--Inferring Spatio-Temporal Variations in the Risk of Extreme Precipitation in the Western United States from Tree Ring Chronologies

本项目旨在通过分析美国西部沿海和内陆地区树木年轮年表记录的水分异常，了解美国西海岸极端冷季降水动态。沿海地区总降水量高的冬季，以少数极端风暴为标志，这些风暴在沿海和内陆地区表现出明显的降水空间格局。基于这一观察结果，本研究将寻求开发一种新的树木气候证据应用，以探索以下问题：a)极端降水变率如何在树木年轮年表网络中表达；B)这些信息能否提供关于导致这些极端事件的风暴路径的时空变化的见解；c)如何对极端降水和风暴路径的联合变率进行建模，以建立一致的、多世纪的两者重建。更广泛的影响包括有可能更好地了解极端降水事件，这些事件通过生命损失和重大财产损失造成重大社会代价。社会利用风险缓解战略（如基础设施、保险）来管理这一负担，这些战略是根据相对较短的仪器记录估计的历史极端降水变异性而设计的，并且可能在人为气候变化下发生变化。该项目将有助于确定这些影响的频率、持续性、复发性和地理格局在过去自然气候变率下是如何变化的。这将为这些变化的原因和未来的可预测性提供重要的见解。该项目还为研究生和博士后研究人员提供支持。外联工作的重点将是与洛杉矶县防汛区、美国陆军工程兵团以及管理该地区极端事件风险的相关机构进行高层讨论。这种直接参与将加强研究产品的应用，并为其设计提供指导。研究成果的创新可视化将通过哥伦比亚水中心提供给公众使用。

This project aims to understand extreme cold-season precipitation dynamics along the west coast of the United States through an analysis of the moisture anomalies recorded by tree-ring chronologies across the coast and interior of the western U.S. Winters with high total precipitation amounts in the coastal regions are marked by a small number of extreme storms that exhibit distinct spatial patterns of precipitation across the coast and further inland. Building from this observation, this research will seek to develop a novel application of dendroclimatic evidence to explore the following questions: a) how is extreme precipitation variability expressed in a network of tree-ring chronologies; b) can this information provide insight on the space-time variability of storm tracks that cause these extreme events; and c) how can the joint variability of extreme precipitation and storm tracks be modeled to develop consistent, multi-centennial reconstructions of both.The broader impacts include the potential to better understand extreme precipitation events which exert significant social costs through both loss of life and substantial damage to property. Society manages this burden using risk mitigation strategies (e.g., infrastructure, insurance) designed for historic extreme precipitation variability that is estimated from relatively short instrumental records and may be changing under anthropogenic climate change. This project will help determine how the frequency, persistence, recurrence and geographic pattern of these impacts have varied in the past under natural climate variability. This will provide important insights into the causes of these shifts and the potential for predictability in the future. This project also provides support for graduate and post-doctoral researchers.Outreach efforts will focus on high-level discussions with the L.A. County Flood Control District, U.S. Army Corps of Engineers, and related agencies that manage extreme event risk in the region. This direct engagement will enhance the application of the research products, as well as provide guidance for their design. Innovative visualizations of research output will be made available through the Columbia Water Center for public use.