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

Andrew Kowler博士被授予美国国家科学基金会地球科学博士后奖学金，与北亚利桑那大学合作，在加州大学洛杉矶分校实施一项研究和扩大参与计划。该研究项目将通过改进团块同位素古温学来回答有关北美西部水平衡控制的基本问题，这将允许利用腹足类动物的壳来重建古代的空气温度。该项目将为了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类似的评估能够在其他干旱地区进行，使气候模式能够更好地检查对全球气候系统的人为扰动可能作出的区域反应。此外，传统上代表性不足的美洲土著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将与与印第安人合作的现有组织（如春季管理研究所、北亚利桑那大学部落环境专业人员、GLOBE、加州大学洛杉矶分校的美洲印第安人计划和美国农业部推广办公室）合作，绘制和描述春季，为高中学生制定水文调查方法课程，提供实地经验，并与当地社区分享数据。本研究通过量化末次盛冰期（LGM: ~24-19 Ka）期间和之后干旱的东南盆地和山脉的气温变化，解决了气候动力学中的一个基本问题。具体来说，团块同位素地球化学将用于检验“季风”假说的核心论断，即LGM时代的南部盆地和山脉的湖泊和湿地主要是由于夏季蒸发减少造成的，而H1高水位则是在17.5-14.5 Ka更温暖、更湿润的夏季发生的。这项研究的结果将揭示基于洞穴和湖泊岩心的代理记录的气候意义，这些记录现在是气候模型验证工作的主要内容。反过来，这将显著改善对非典型短时间间隔的中尺度气候模拟，但人们对过去导致潮湿条件的大气环流模式知之甚少。改进后的模型还将为当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.