P2C2: Evaluating North Pacific Hydroclimate during the Holocene Using the Denali Ice Core Archive

该项目旨在开发阿拉斯加亨特山冰芯档案中全新世长度的水文气候记录，并在现有古气候数据和模型的背景下评估北太平洋水文气候的变化。最近的观测和模拟研究表明，20世纪初和20世纪70年代以来，太平洋多年代际变率与北极变暖之间存在联系，这在一定程度上推动了该项目的开展。太平洋多年代际变率对北极气候的影响对海冰范围以及北极放大、海冰损失和中纬度冬季变率增强之间的可能联系具有重要意义。先前对亨特山冰芯记录的研究表明，在工业时代（自1850年以来）观测到的积雪量翻倍和夏季融雪量增加60倍与太平洋多年代际变率有关，这在过去一千年中是独一无二的。这项研究试图证实，同样的驱动因素是否与整个全新世有关。确定太平洋-北极遥相关在暖期和仪器周期以外的突发事件以及上个千年期间的响应方式，将为了解地球系统的敏感性提供有价值的见解。研究人员将在亨特山冰芯档案的不同部分结合几种互补技术，特别关注两个208米的地表到基岩岩芯的底部20米。初步放射性成因同位素（14-碳）分析表明，基底冰的年龄超过1万年。具体项目目标包括：1)利用额外的14碳测量、温度年代学、激光消融ICPMS测量来扩展年度层数和一套冰川学模型的时间尺度开发；2)水文气候代理发展，包括区域水分估算的积雪量（基于年代学和冰流模型），综合水循环的稳定水同位素，大气动力学的微量元素化学；3)将全新世长度的Mt. Hunter记录与现有的北太平洋冰芯阵列和其他区域古气候资料相结合；4)全新世长度Mt. Hunter记录与地球系统模型的比较。潜在的更广泛影响包括多方面的方法，包括在国际研究合作的背景下支持和指导早期职业科学家和博士生。研究人员将与科罗拉多州立大学的教职员工和美国国家公园管理局的教职员工合作，根据亨特山冰芯记录制作教育工具包，目标是阿拉斯加和缅因州学校4-12年级的教育。该奖项反映了美国国家科学基金会的法定使命，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。

This project broadly seeks to develop a Holocene-length hydroclimate record from the Mt. Hunter (Alaska) ice core archive and evaluate North Pacific hydroclimate variability in context with existing paleoclimate data and models. This project is motivated in part by recent observational and modeling studies that demonstrate a connection between Pacific multidecadal variability and Arctic warming during the early 20th century and since the 1970s. The impact of Pacific multidecadal variability on Arctic climate has considerable implications for sea ice extent and possible linkages between Arctic amplification, sea ice loss, and enhanced mid-latitude winter variability. Previous work on the Mt. Hunter ice core record demonstrates that the observed doubling of snow accumulation and 60-fold increase in summer melt during the industrial era (since the year 1850) is linked to Pacific multidecadal variability and is unique in the last millennium. The research seeks to confirm if the same drivers are relevant for the entire Holocene. Establishing how the Pacific-Arctic teleconnection responded during warm intervals and abrupt events outside of the instrumental period and last millennium would provide valuable insight into Earth system sensitivity.The researchers will combine several complementary techniques in different sections of the Mt. Hunter ice core archive, with specific focus on the bottom 20 meters of the twin 208-meter surface-to-bedrock cores. Preliminary radiogenic isotope (14-Carbon) analyses demonstrate that the basal ice is more than 10,000 years old. Specific project objectives include: 1) time scale development using additional 14-Carbon measurements, tephrochronology, laser ablation ICPMS measurements to extend annual layer counting, and a suite of glaciological models; 2) hydroclimate proxy development, including snow accumulation for regional moisture estimates (based on chronology and ice flow models), stable water isotopes for the integrated water cycle, and trace element chemistry for atmospheric dynamics; 3) integration with the new Holocene-length Mt. Hunter record with the existing North Pacific ice core array and other regional paleoclimate data; and 4) comparison of the new Holocene-length Mt. Hunter record with Earth system models.The potential Broader Impacts include a multi-faceted approach that includes support and mentoring of an early career scientist and a doctoral student in the context of international research cooperation. The researchers will collaborate with Colorado State University faculty and U.S. National Park Service faculty personnel to fabricate educational kits based on the Mt. Hunter ice core record that target grades 4-12 education in Alaska and Maine schools.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.