EAGER: A Comparison of Lacustrine Carbonate d18O and Organic Matter dD from Drought Sensitive Lakes in the Western United States

仪器气候记录表明，北美西部的干旱模式对太平洋变率以及厄尔Niño南方涛动和北美季风之间的相互作用很敏感。需要对这些模式过去的行为有更深入的了解，以改进对未来干旱和降雨周期的预测。这项研究将：1)为在湖泊系统中使用三角洲-氘记录提供概念证明，在湖泊系统中，单相碳酸盐无法用于三角洲-18氧分析；2)为不断增长的定量古气候数据集网络增加一个关键的时空视角，以帮助我们理解北美西部的干旱模式和相关的天气气候远相关。该项目将从过去2000年美国西部两个干旱敏感湖泊的两个封闭盆地湖泊中，以百年为单位，开发湖泊沉积物有机质del-D记录。第一个是卡斯特湖（Castor Lake），这是华盛顿州一个研究得很充分的系统，十年来一直在使用湖泊水位传感器、水温记录仪、沉积物收集器、气象站，以及每年对地面、湖泊和溪流进行水化学和稳定同位素采样。Castor湖氧同位素的年代际记录已经发表，并提供了与藻类del-D进行比较的机会。第二个湖，格雷厄姆湖，也是一个干旱敏感系统，位于新墨西哥州，一个对干旱研究非常感兴趣的地区。该团队已经访问了该系统，验证了它符合他们提出的工作标准，并计划为本研究恢复一系列重叠的核心。更广泛的影响是，如果这种新的del-D技术在这些没有单相碳酸盐的湖泊中取得成功，那么由此产生的美国西部古干旱数据集网络将提供有关干湿循环时间、持续时间和强度的重要新信息，并结合正在进行的研究，确定晚全新世北美干旱的空间格局。

Instrumental climate records indicate that drought patterns in western North America are sensitive to Pacific Ocean variability and to interactions between the El Niño Southern Oscillation, and the North American monsoon. A deeper understanding of the past behavior of these modes is needed to improve predictions of future drought and pluvial cycles. This proposed research would: 1) provide proof of concept for the use of delta-Deuterium records in lake systems where single phase carbonates are not available for delta-18 Oxygen analyses and 2) add to a growing a network of quantitative paleoclimate data sets that would add a critical spatial and temporal perspective to our understanding of aridity patterns in western North America and associated synoptic climate teleconnections.The proposed project will develop lake sediment organic matter del-D records from two closed-basin lakes at centennial scale from two drought-sensitive lakes in the western US for the last 2,000 years. The first, Castor Lake, is a well-studied system in Washington State that has been instrumented for a decade with lake level sensors, water temperature loggers, sediment traps, a weather station, and annual ground, lake and stream sampling for water chemistry and stable isotopes. A decadal scale record of oxygen isotopes has been published from Castor Lake, and offers an opportunity for comparison with Algal del-D. The second lake, Graham Lake, is also a drought-sensitive system located in New Mexico, a region of great interest for drought studies. The team has visited this system, verified that it meets the criteria for their proposed work and plans to recover a series of overlapping cores for this study.The broader impacts are that if this new del-D technique is successful in these lakes without single phase carbonates, the resulting network of paleodrought datasets from the western US would provide important new information on the timing, duration and magnitude of wet/dry cycles and combined with ongoing research, identify spatial patterns of aridity in North America during late Holocene.