Developing a Novel Temperature Proxy to Test Hypotheses about Atmospheric Circulation in Western North America during the Last Deglaciation

Andrew Kowler博士被授予NSF地球科学博士后奖学金，与北方亚利桑那大学合作，在加州-洛杉矶大学实施一项研究和扩大参与计划。该研究项目将回答有关控制水平衡的基本问题，在北美西部通过改进成团同位素古温度计，这将允许利用腹足类贝壳重建古代气温。该项目将为理解该地区长期水文气候敏感性背后的驱动力做出宝贵贡献。这项工作的输出将使人们能够对其他干旱地区出现的湿润期进行类似的评估，使气候模型能够更好地研究区域对全球气候系统人为扰动的可能反应。此外，传统上代表性不足的美洲原住民人口的经济和文化福祉取决于城市和农村地区水文资源的可用性和可持续性。拟议的扩大参与活动通过在现有的教育和保护倡议之间建立直接联系来解决这一问题。PI将与与美国原住民合作的组织（如春季管理研究所，北方亚利桑那大学部落环境专业人员，地球仪，加州大学洛杉矶分校的美国印第安人项目和美国农业部推广办事处）合作，绘制和描述泉水，为高中生开发水文调查方法课程，提供实地经验，并与当地社区分享数据。 这项研究解决了气候动力学的一个基本问题，量化空气温度变化与潮湿的间隔在现在干旱的东南盆地和山脉，在末次冰期最大期（LGM：~24-19 Ka）。具体而言，聚集同位素地球化学将被用来测试的核心断言的“季风”假说，即末次盛冰期湖泊和湿地在南部盆地和山脉主要是由于减少夏季蒸发，相反，H1高水位发生在温暖，潮湿的夏天，17.5-14.5 Ka。这项研究的结果将揭示洞穴和湖泊核心为基础的代理记录，现在的气候模式验证工作的主食的气候意义急需的光。反过来，这将显着改善中尺度气候模拟的非典型的，但知之甚少的大气环流模式，导致在过去的潮湿条件的短暂间隔。改进的模型还将为目前对温度与长期干旱之间关系的理解提供信息，这是西南古气候学界非常感兴趣的一个话题。

Dr. Andrew Kowler has been awarded an NSF Earth Sciences postdoctoral fellowship to implement a research and broadening participation plan at the University of California - Los Angeles, in collaboration with Northern Arizona University. The research project will answer fundamental questions about controls on water balance in western North America through refinement of clumped isotope paleothermometry, which will allow utilization of gastropod shells for reconstructions of ancient air temperatures. This project will make a valuable contribution to the understanding of the driving forces behind this region's long-term hydroclimatic sensitivity. Exportation of this work will enable similar evaluations to be conducted for wet intervals that occurred in other arid regions, leaving climate models better equipped to examine possible regional responses to anthropogenic perturbations of the global climate system. Moreover, the economic and cultural well-being of traditionally underrepresented Native American populations depends upon the availability and sustainability of hydrologic resources in both urban and rural areas. The proposed broadening participation activities address this through establishment of a direct link between existing educational and conservation initiatives. The PI will partner with established organizations that work with Native Americans (like Spring Stewardship Institute, Northern Arizona Univeristy Tribal Environmental Professionals, GLOBE, UCLA's American Indian Program, and USDA Extension offices) to map and characterize springs, develop curriculum on hydrological survey methods for high school students, provide field experiences, and share data with local communities. This study addresses a fundamental question in climate dynamics by quantifying air temperature changes associated with wet intervals in the now-arid southeastern Basin and Range, during and after the Last Glacial Maximum (LGM: ~24-19 Ka). Specifically, clumped isotope geochemistry will be used to test the core assertion of the "Monsoon" hypothesis that LGM age lakes and wetlands in the southern Basin and Range primarily resulted from a reduction in summertime evaporation, in contrast to H1 highstands which occurred in response to warmer, wetter summers, 17.5-14.5 Ka. Results from this study would shed much needed light on the climatic significance of speleothem- and lake core-based proxy records, now the staple of climate model validation efforts. This, in turn, will markedly improve meso-scale climate simulations of short-lived intervals of atypical, yet poorly understood modes of atmospheric circulation that led to wetter conditions in the past. Improved models will also inform current understandings of the relationship between temperature and long-term drought, a topic of intense interest to the Southwestern paleoclimatological community.