Collaborative Research: Spatial and Temporal Patterns of Drought in Western North America during the Holocene

合作研究：全新世北美西部干旱的时空模式

• 批准号: 0902200
• 负责人: Mark Abbott
• 金额: $ 20.84万
• 依托单位: University of Pittsburgh
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 2009
• 资助国家: 美国
• 起止时间: 2009-09-01 至 2011-08-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=0902200&HistoricalAwards=false
• 关键词: Collaborative; Research; Spatial; Temporal; Patterns

This award is funded under the American Recovery and Reinvestment Act of 2009 (Public Law 111-5).This grant produces paleoclimate datasets recording the timing, duration, frequency and magnitude of aridity cycles on a network of paired open and closed micritic basins along the western cordillera of North America from the Pacific NW to the Canadian Arctic. The project employs hydrologic and stable isotope mass balance models to provide quantitative estimates of precipitation and relative humidity changes. The project explores how the temporal-geographic patterns of aridity changed during the Holocene and uses advanced data processing techniques to test hypotheses concerning the periodicities in the paleoclimate archives. These results are used to infer the nature of potential modes of Pacific Ocean variability and to document how they have changed over time. The project tests hypotheses concerning the causes and magnitude of climate variability in the study region during the Holocene. The project also synthesizes data from the literature with ongoing work in Tropical South America to investigate large-scale Pacific Ocean forcing over a range of timescales. Synthesis of these records will result in a better understanding of the Pacific climate system and improved predictability for aridity cycles in western North America.Lake levels along the western cordillera have been relatively stable during the past ~6ka creating high resolution archives during the period of time targeted for most intense study. During the early Holocene megadroughts significantly lowered water levels regionally thereby limiting the resolution to multi-decadal to century scale prior ~6ka. Geochronology is provided by 137Cs, 210Pb, 14C, tephra chronology and geomagnetic correlation. The same methods are applied at all study sites to simplify data interpretation and increase robustness of findings. Multiproxy studies will include stable isotopes, grayscale, diffuse spectral reflectance, XRF, magnetic measurements, and organic and inorganic carbon by loss on ignition. The group collaborates with the University of British Columbia, who use chironomid assemblages to reconstruct paleotemperatures. The multi-millennial hydrologic record with sub-decadal resolution is then compared with high resolution coupled ocean atmosphere GCM simulations currently being conducted by a collaborator at Purdue University.The work is relevant to western North America where populations are rapidly expanding and water resources are stressed. The relatively sparse preinstrumental climate records for this region indicate that it is highly sensitive to Pacific Ocean variability and to the interaction between the PDO and AMO. A deeper understanding of the past behavior of these modes of variability is needed to improve predictive capabilities. The goal is to investigate climatic change at a time-resolution relevant to human society, and answer questions such as: How have the intensity and periodicity of droughts and pluvials changed during the Holocene? What is the spatial pattern of aridity cycles in western North America during this period? What boundary conditions and forcing factors are related to extreme droughts and pluvials?

该奖项是根据2009年的《美国复苏与重新恢复法》（公法111-5）资助的。该赠款生产的古气候数据集记录了在沿着沿沿沿沿沿沿沿途和封闭的封闭的微型盆地网络上进行的时间，持续时间，频率，频率和幅度从太平洋西北到加拿大北极地区的北美西部科迪利拉。该项目采用水文和稳定的同位素质量平衡模型来提供降水和相对湿度变化的定量估计。该项目探讨了全新世期间干旱的时间地理模式如何改变，并使用先进的数据处理技术来测试有关古气候档案中周期性的假设。这些结果用于推断太平洋变异性潜在模式的性质，并记录它们随时间变化的方式。该项目测试假设全新世期间研究区域中气候变异性的原因和幅度。该项目还通过在热带南美进行的持续工作来调查大规模太平洋强迫在各种时间尺度上进行大规模的太平洋，从而综合了文献中的数据。这些记录的综合将使西部北美西部干旱循环的太平洋气候系统和改善的可预测性有更好的了解。在过去的北美西部的湖泊水平相对稳定〜6KA 〜6KA在时间内创建高分辨率档案针对最激烈的研究。在全新世早期，巨型岩质大大降低了区域的水位，从而限制了在〜6KA之前限制多年到世纪的分辨率。地质学由137CS，210pb，14c，Tephra年表和地磁相关提供。在所有研究地点都应用了相同的方法，以简化数据解释并增加发现的鲁棒性。多氧研究将包括稳定的同位素，灰度，弥漫性光谱反射率，XRF，磁性测量以及有机和无机碳，通过点火损失。该小组与不列颠哥伦比亚大学合作，他们使用Chiromid组合来重建古植物。然后，将具有亚少年分辨率的多千年水文记录与普渡大学合作者目前正在进行的高分辨率耦合海洋气氛GCM模拟进行比较。该区域的相对稀疏的摄影前气候记录表明，它对太平洋变异性以及PDO和AMO之间的相互作用高度敏感。需要更深入地了解这些可变性模式的过去行为，以提高预测能力。目的是在与人类社会相关的时间分辨率上调查气候变化，并回答以下问题：在全新世期间，干旱和普鲁维亚人的强度和周期性如何发生变化？在此期间，北美西部的干旱周期的空间模式是什么？哪些边界条件和强迫因素与极端的干旱和普鲁维亚人有关？