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

该项目旨在通过建立长期建立的美国西南部干旱树轮记录以及新的试点数据，以全面的方式调查美国西南部的水文气候变异性。这将通过以下方式实现：(A)综合使用广泛使用的和新出现的树木年轮、洞穴和湖泊代用品；(B)对过去2000年的年际至年代际分辨率进行重点研究，对早期全新世及其明显更长和更严重的干旱极端进行更粗略的检查；(C)部署广泛的监测、校准和相互比较的代用品；(D)除对湿度敏感的代用品外，特别注重多种温度代用品；(E)强调季节性，特别是区分冷季和暖季(季风)的变率；以及(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、西南水文气候变异性原因和模型现实性的理解。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在一起产生过去的干旱和暴雨的？(2)如何最好地使用多代理方法来研究一系列时间尺度上极端水文气候事件的各种特征，从年际到百年？(3)当地温度异常与水气候极端事件是否与大范围温度有关，还是更具地区性，与水文气候反馈有关？(4)冬季和夏季季风变化对西南大雨期和雨季的相对贡献是什么？(5)在最新的地球系统模型中，水文气候极端事件及其驱动因素的表现如何？(6)对干旱及其驱动因素的精细理解如何改进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训；通过亚利桑那州的生物圈2对K-12和关于气候变化的一般公众教育进行外联；通过多大学科罗拉多河研究小组的定期外联努力，与农民、牧场主、公共卫生、水资源管理人员和城市管理人员接触，特别强调科罗拉多河水资源管理人员和用户。

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.