Collaborative Resesarch: P2C2--The Flavors of Southwest Hydroclimatic Extremes

本项目旨在通过长期建立的西南干旱树木年轮记录和新的试点数据，全面研究美国西南地区的水文气候变化。这将通过(a)综合使用广泛使用的和新出现的树木年轮、洞穴和湖泊代用指标来实现；(b)利用年际到十年的分辨率，重点关注过去2000年，并对全新世早期及其明显更长和更严重的极端干旱进行了更粗略的研究；(c)采用广泛的监测、校正和交叉比较代理指标；(d)除了湿度敏感指标外，还特别关注多种温度指标；(e)强调季节性，特别是区分冷季和暖季（季风）变化；(f)整合代理记录、气候模拟和代理正演模拟，以增加对区域气候反馈、西南水文气候变率的原因和模式真实性的理解。该项目旨在解决六个主要的科学问题：(1)湿度和温度异常是如何结合起来产生过去的干旱和雨淋的？(2)如何利用多代理方法在年际到百年的时间尺度范围内研究各种类型的极端水文气候事件？(3)与水气候极端事件相关的局地温度异常是与大尺度温度有关，还是与水气候反馈有关？(4)冬季风和夏季风的变化对西南特大干旱和暴雨期的相对贡献是什么？(5)在最先进的地球系统模型中，极端水文气候及其驱动因素的表现有多好？(6)对干旱及其驱动因素的精确理解如何提高对未来干旱风险的估计？更广泛的影响包括支持研究生和本科生的培养；通过亚利桑那州的生物圈2向K-12和普通公众宣传气候变化；利益相关者与农民、牧场主、公共卫生、水资源管理者和城市管理者的接触，通过多所大学科罗拉多河研究小组的定期外展工作，特别强调科罗拉多河水资源管理者和用户。

This project aims to investigate hydroclimatic variability in the American Southwest (SW) in a comprehensive manner by building on the long-established tree-ring record of SW drought as well as new pilot data. This will be accomplished by (a) integrating the use of both widely-used and newly emerging tree-ring, cave and lake proxies; (b) using an interannual- to-decadal-resolution focus on the last 2,000 years, and a coarser examination of the earlier Holocene and its apparent longer and more severe dry extremes; (c) deploying a broad mix of monitoring, calibration and cross-comparison of proxies; (d) specifically focusing on multiple temperature proxies, in addition to moisture sensitive proxies; (e) emphasizing seasonality, particularly the disentangling of cool-season and warm-season (monsoon) variability; and (f) integrating proxy records, climate modeling, and proxy forward modeling to increase understanding of regional climate feedbacks, causes of SW hydroclimatic variability, and model realism. The project aims to address six primary science questions: (1) How do moisture and temperature anomalies combine to produce the droughts and pluvials of the past? (2) How can a multiproxy approach best be used to investigate the various flavors of extreme hydroclimatic events over a range of time scales, interannual to centennial? (3) Are local temperature anomalies associated with hydroclimate extremes linked to large-scale temperatures, or are they more regional and related to hydroclimatic feedbacks? (4) What are the relative contributions of winter versus summer monsoon variations to SW megadrought and pluvial periods? (5) How well are hydroclimatic extremes and their drivers represented in state-of-the-art Earth System Models? (6) How can a refined understanding of drought and its drivers improve estimates of future drought risk?The broader impacts include supporting the training of graduate and undergraduate students; outreach to K-12 and general public education on climate variability via the Biosphere2 in Arizona; and stakeholder engagement with farmers, ranchers, public health, water managers, and urban managers with special emphasis on Colorado River water managers and users via regular outreach efforts of the multi-university Colorado River Research Group.