Collaborative Research: P2C2--Multi-Time-Scale Climate Dynamics in California (CA): An Integrated Multi-Proxy Stalagmite, Monitoring, and Modeling Approach

北美西南部（SWNA）是世界上气候最敏感的地区之一，具有内在多变的水文气候。有很多证据表明，在末次冰期和全新世，该地区的水文气候在次十年到千年尺度上发生了反复的大的制度转变，但驱动这种变化的机制仍然不确定。鉴于过去的这种可变性和未来气候变化的潜在规模，需要更好地了解水文气候对扰动的反应和潜在的驱动机制。该研究小组的目标是生成一组多代理方解石和流体包裹体记录，解决了在亚十年到百年尺度，从中部和南部的塞拉内华达州，加利福尼亚州的四个石笋跨越最后一次冰消期通过全新世。 通过整合高精度铀钍定年、洞穴监测、多石笋记录和地球系统建模（单强迫水同位素跟踪模拟），研究小组将（1）评估北太平洋风暴路径行为和由此产生的降水信号如何在石笋代理记录中存档，以及（2）应用这些知识来研究在过去21,000年变化的环境强迫背景下这种降水响应的机制。 整合新的塞拉利昂内华达州记录与补充石笋记录正在开发的沿海和北方CA将允许一个区域性的广泛调查的机制，影响风暴轨迹的行为和降水模式在SWNA。自21 ka模拟以来，与新的同位素启用的瞬态气候演变（iTraCE-21 ka模型）的数据模型比较将进一步深入了解美国西部气候对不同强迫的全球驱动因素和响应时间。 一个综合的洞穴监测石笋代理水同位素建模方法可以提供（1）深入了解气候和岩溶过程如何印记石笋代理记录，以及（2）急需的定量约束如何在美国西部的古降水应对不断变化的气候条件。包括三个外展活动，将代表性不足的高中生和本科生纳入Sierran石笋项目，并向公众分发调查结果。(1)一个本科生团队（n=8）将通过在加州大学戴维斯分校（加州C3气候变化）开发垂直综合项目（VIP）正式融入研究。 该计划由赫尔姆斯利慈善信托基金向VIP财团（UCD是参与的16所大学之一）提供资助，将涉及每周研讨会，同行指导和基于团队的洞穴监测部分研究。(2)将为西班牙裔服务机构瓦卡维尔（CA）高中开发一个以气候科学为基础的课程。课程将整合石笋研究和批判性思维技能的目标发展方面。(3)一个互动的洞穴展览，包括虚拟现实研究之旅和三维石笋重建将建立的塞拉内华达州娱乐公司（业主的两个Sierran洞穴的研究目标）。 该奖项反映了NSF的法定使命，并通过使用基金会的知识价值和更广泛的影响审查标准进行评估，被认为值得支持。

Southwest North America (SWNA) is one of the world's most climatically sensitive regions with inherently variable hydroclimate. Much evidence exists for repeated, large regime shifts in this region's hydroclimate at the sub-decadal to millennial-scale during the last glacial cycle and Holocene, but the mechanisms driving this change remain uncertain. In the context of this past variability and the potential magnitude of future climate change, a refined understanding of the hydroclimate response to perturbation and of the underlying driving mechanisms is needed. The research team aims to generate a set of multiproxy calcite and fluid inclusion records, resolved at the sub-decadal to centennial-scale, for four stalagmites from the central and southern Sierra Nevada, CA that span the last deglaciation through Holocene. By integrating high-precision Uranium-Thorium dating, cave monitoring, multi-stalagmite records, and Earth system modeling (single-forcing water-isotope tracking simulations), the research team will (1) evaluate how North Pacific storm track behavior and the resulting precipitation signal is archived in the stalagmite proxy records, and (2) apply this knowledge to investigating the mechanisms underlying this precipitation response in the context of the changing environmental forcings of the past 21,000 years. Integration of the new Sierra Nevada records with complementary stalagmite records being developed for coastal and northern CA will permit a regionally expansive investigation of the mechanisms influencing storm track behavior and precipitation patterns in SWNA. Data-model comparisons with the new isotope-enabled Transient Climate Evolution since 21-ka simulations (iTraCE-21ka model) will provide further insight into the global drivers and response time of climate in the western U.S. to different forcings. An integrated cave monitoring-stalagmite proxy-water isotope modeling approach could provide (1) insight into how climate and karst processes imprint stalagmite proxy records, and (2) much needed quantitative constraints on how paleo-precipitation in the western U.S. responded to evolving climate conditions.The potential Broader Impacts (B.I.) include three outreach activities to integrate under-represented high school and undergraduate students into the Sierran stalagmite project and distribute the findings to the public. (1) A team (n=8) of undergraduate students will be formally integrated into the research through the development of a Vertically Integrated Project (VIP) at UC Davis (C3Climate Change in California). This program, supported by a grant from the Helmsley Charitable Trust to the VIP Consortium (UCD is one of 16 universities that participate), will involve weekly seminars, peer-mentoring, and team-based research in the cave-monitoring component. (2) A climate science-based curriculum will be developed for Vacaville (CA) High School, a Hispanic serving institution. The curriculum will integrate aspects of the stalagmite study and target development of critical-thinking skills. (3) An interactive cave exhibit involving a virtual reality research tour and 3-D stalagmite reconstructions will be built for the Sierra Nevada Recreation Corporation (owner of two of the Sierran caves targeted for study). The project would also include support for graduate education.This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.