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

考虑到未来极端气候的潜在变化，了解洪水和干旱等对社会和生态系统产生重大影响的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发挥了关键作用，但古气候代用物的偏差仍然是重建和解释过去气候极端事件的主要挑战。这尤其适用于北美西海岸，在那里，有限数量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，包括一系列仪器记录中没有代表的极端气候，来解决仪器前的极端气候捕获问题。具体而言，该项目的目的是：(1)从档案和数据库中提取19世纪的历史数据，获得亚季节降水和雪频率重建；(2)利用树木年轮数据评估现有记录捕捉西海岸极端水文气候（重点关注大气河流事件）和季节性降水的能力；(3)综合历史数据和树木年轮数据，建立19世纪极端事件的空间气候面，并利用再分析数据、网格化古气候重建数据和古气候模式输出评估极端事件的天气气候驱动因素。潜在的更广泛影响（bi）包括提高对季节性极端气候事件的理解，这些事件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、消防和其他社会部门都有影响。从这项研究中获得的信息对水资源管理者、气候建模者和其他对过去极端事件特征（包括影响和驱动机制）以及未来极端水文气候感兴趣的人可能有用。本项目的进一步影响包括：(1)研究生在研究方法和传播、科学传播和教育推广方面的教育和培训；(2)让本科生参与动手研究经验，使他们能够通过科学过程进行工作；(3)新的、空间明确的气候重建对NOAA古气候库的贡献；(4)利用我们的研究主题的兴奋，通过与莫尔黑德天文馆和科学中心合作的K-12教育推广活动，吸引未来几代科学家。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。

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.