Collaborative Research: P2C2--High Frequency Hydroclimate Extremes and Synoptic Climate Drivers in Western North America at the End of the Little Ice Age

鉴于极端气候未来可能发生的变化，了解对社会和生态系统有重大影响的洪水和干旱等极端气候事件变得尤为重要。 古气候数据在将最近的水文气候极端事件置于长期背景下方面发挥了关键作用，但古气候代理的偏差仍然是重建和解释过去气候极端事件的主要挑战。这特别适用于北美西海岸，那里数量有限的季节性极端降水事件占年降水总量的很大比例。这项研究将整合历史气候学和树木气候学，通过关注19世纪，包括一系列在仪器记录中没有代表的极端气候的时间段，来解决仪器前对极端气候的捕捉。具体而言，该项目的目标是：（1）从档案和资料库中提取19世纪的历史数据，以获得亚季节降水和降雪频率重建;（2）利用树木年轮数据评估现有记录捕捉水文气候极端情况的能力（重点是大气河流事件）和西海岸的季节性降水;（3）整合历史和树木年轮数据，为19世纪的极端事件创建空间气候表面，并使用再分析数据、网格化古气候重建数据和古气候模式输出来评估这些极端事件的天气气候驱动因素。包括提高对季节性极端气候事件的认识，具有广泛的社会影响，因为这些极端事件是代价高昂的危害，对农业、供水、发电、火灾和社会其他部门都有影响。从这项研究中获得的信息可能对水资源管理者，气候建模者和其他对过去极端事件的特征感兴趣的人有用，包括影响和驱动机制，以及未来的水文气候极端事件。该项目的进一步影响包括：（1）在研究方法和传播、科学传播和教育推广方面对研究生进行教育和培训;（2）让本科生参与实践研究经验，使他们能够通过科学过程开展工作;（3）为NOAA古气候学资料库提供新的、空间清晰的气候重建;以及（4）利用我们研究主题的兴奋点，通过K-12项教育推广活动，涉及与莫尔黑德天文馆和科学中心的合作伙伴关系。该奖项反映了NSF的法定使命，并已被认为是值得通过评估使用基金会的智力价值和更广泛的支持影响审查标准。

Understanding extreme climate events like floods and droughts, which have major impacts on society and ecosystems, has become particularly important in light of potential future changes in climatic extremes. Paleoclimate data have played a critical role in placing recent hydroclimate extremes within a longer-term context, but biases in paleoclimate proxies remain a major challenge for the reconstruction and interpretation of past climate extremes. This is particularly applicable to the North American West Coast where a limited number of seasonal extreme precipitation events account for a large proportion of annual precipitation totals. This research will integrate historical climatology and dendroclimatology to address pre-instrumental capture of extremes through a focus on the 1800s, a time period including a range of climate extremes that are not represented in the instrumental record. Specifically, the aims of this project are to: (1) extract 19th century historical data from archives and repositories to derive subseasonal precipitation and snow frequency reconstructions; (2) use tree-ring data to assess the ability of existing records to capture hydroclimatic extremes (with a focus on atmospheric river events) and seasonally-specific precipitation on the West Coast; and (3) integrate historical and tree-ring data to create spatial climate surfaces for extreme events in the 1800s and use reanalysis data, gridded paleoclimate reconstruction data, and paleoclimate model output to assess synoptic climate drivers of those extremes.The potential Broader Impacts (B.I.) include improved understanding of extreme climate events at a seasonal level has broad societal implications, as these extremes are costly hazards with implications for agriculture, water supply, power generation, fire, and other sectors of society. The information derived from this research is potentially useful to water managers, climate modelers, and others who are interested in the characterization of past extreme events, including impacts and driving mechanisms, as well as future hydroclimate extremes. Further impacts of this project include: (1) education and training of graduate students in research methods and dissemination, science communication, and educational outreach; (2) involving undergraduates in hands-on research experiences, allowing them to work through the scientific process; (3) contribution of new, spatially explicit climate reconstructions to the NOAA Paleoclimatology repository; and (4) capitalizing on the excitement of our research themes to engage future generations of scientists through K-12 educational outreach activities involving a partnership with the Morehead Planetarium and Science Center.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.