Collaborative Research: Spatiotemporal Variability and Drivers of East-west Hydroclimate Anti-phasing in the Midcontinental United States During the Last 2000 Years

合作研究：过去 2000 年美国大陆中部东西向水文气候反阶段的时空变化和驱动因素

• 批准号: 1903607
• 负责人: Karlyn Westover
• 金额: $ 5.65万
• 依托单位: Indiana State University
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 2019
• 资助国家: 美国
• 起止时间: 2019-07-01 至 2023-06-30
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=1903607&HistoricalAwards=false
• 关键词: Collaborative; Research; Spatiotemporal; Variability; Drivers

The midcontinental United States (US) is one of the world's largest agricultural centers and home to more than 70 million Americans. In recent decades, hydro-climate events in this region have intensified, with generally more frequent and prolonged flooding in the eastern midcontinental US and more severe and sustained droughts in the west. This east-west pattern of hydro-climate variability may be persistent and long-standing, resulting from natural large-scale ocean-atmosphere circulation regimes, or it may be a more recent manifestation of anthropogenic climate change. Given that instrumental meteorological records typically span no more than ~150 years, investigation of the causes of hydroclimate changes in the Midwest on timescales of hundreds to thousands of years requires analysis of high-resolution paleoclimate records, the development of which is the primary objective of this research. Through geochemical analysis of lake sediment, the researchers will produce a series of records of lake-level and precipitation changes that will span the past 2000 years in order to determine the spatiotemporal patterns and underlying drivers of midcontinental hydro-climate variability. This research will 1) produce a long timescale perspective on hydroclimate that will inform water resource management strategies, and 2) elucidate regional-scale responses of hydro-climate to increasing global temperatures. As part of this project, the investigators will be working with local, state, and federal agencies, including the United States Geological Survey, to incorporate the results of this research into flood model development efforts and fluvial erosion hazard mitigation. The data from this project will additionally inform and benefit research into climate-society interactions, including the impact of abrupt and long-term climate changes on Native American societies that once populated the midcontinental US, but abruptly abandoned much of the region ~600 years ago. Methodologically, there are three specific objectives of this research. 1) The researchers will reconstruct changes in atmospheric circulation and precipitation seasonality in the midcontinental US during the last 2000 years using oxygen isotope (d18O) measurements of carbonate minerals in sediment from two hydrologically open lakes. 2) The researchers will produce records of local hydroclimate conditions (precipitation:evaporation ratios and lake-level variability) using d18O, grain size, carbon:nitrogen, and diatom analysis of sediment from four hydrologically closed lakes. 3) The researchers will statistically evaluate the open and closed lake hydro-climate records in the context of atmosphere-ocean variability known from empirical paleoclimate records and model simulations. Using these approaches, the researchers will quantify the respective influences of atmospheric circulation and precipitation seasonality on regional midcontinental hydro-climate and determine the underlying role(s) of ocean-atmosphere processes. Specifically, the investigators will test three hypotheses. 1) Multi-decadal to centennial hydroclimate variability in the midcontinental US during the last 2000 years was characterized by an east-west hydroclimate dipole with its hinge line located between the Great Plains and Midwest at ~96oW. 2) Hydroclimate dipole variability was driven by atmospheric circulation resembling the Pacific North American mode that altered seasonal precipitation patterns. 3) Midcontinental hydroclimate and atmospheric circulation anomalies were predominantly controlled by Pacific basin atmosphere-ocean processes. A critical component of this research is the education and training of undergraduate and graduate students while actively working to increase diversity in STEM fields by recruiting and supporting women and underrepresented minorities in science. One PhD, 2 MSc, and 4 undergraduate students will be directly supported by this project, while several others supported by other sources will also contribute. Because translation of science to the public is a critical component of any effective research project, the researchers and their institutions will engage in outreach activities including the development of an educational module for 4th to 9th grade students focused on 1) Midwest climate, both paleo and modern, 2) paleoclimate reconstruction techniques, and 3) water resource variability. This module will be developed and implemented by IUPUI's Center for Earth and Environmental Sciences and made publicly available for other educators to use. The researchers will work with the Indiana State Museum to incorporate the projects results into an interactive exhibit on midcontinental Native Americans.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.

美国中部（美国）是世界上最大的农业中心之一，是超过7000万美国人的所在地。近几十年来，该地区的水力气候事件加剧了，在美国东部中部地区，通常更频繁和长时间的洪水泛滥，西方的干旱更加严重和持续的干旱。这种水性气候变化的东西模式可能是由于天然的大型海洋 - 大气循环制度而引起的，或者可能是人为气候变化的最新表现。鉴于工具性的气象记录通常不超过约150年，因此对中西部氢气气候变化的原因进行了数百至数千年的时间，需要分析高分辨率古气候记录，这是这项研究的主要目标。通过对湖泊沉积物的地球化学分析，研究人员将产生一系列湖泊水平和降水变化的记录，这些变化将跨越2000年，以确定时空模式以及中脑气候变化的基本驱动因素。这项研究将1）对氢化气候的长时间观点，这将为水资源管理策略提供依据，2）阐明水电气候对增加全球温度的区域尺度反应。作为该项目的一部分，调查人员将与包括美国地质调查局在内的地方，州和联邦机构合作，将这项研究的结果纳入洪水模型开发工作和缓解河流侵蚀危害中。该项目的数据还将为气候社会互动的研究提供信息和利益研究，包括突然和长期气候变化对曾经占美国中部美国的原住民社会的影响，但突然放弃了600年前的大部分地区。 从方法上讲，这项研究有三个特定的目标。 1）研究人员将使用氧同位素（D18O）测量在两个水文开放的湖泊中对碳酸盐矿物质的氧同位素（D18O）测量，在过去2000年中，美国中部美国大气循环和降水季节性的变化。 2）研究人员将使用D18O，晶粒尺寸，碳：氮和硅藻分析，从四个水文封闭的湖泊中，使用D18O，晶粒尺寸，碳：氮和硅藻分析，生成局部氢气候条件的记录（降水量：蒸发比和湖泊水平的变异性）。 3）研究人员将在经验古气候记录和模型模拟的大气 - 海洋变异性的背景下统计评估开放和封闭的水电气候记录。使用这些方法，研究人员将量化大气循环和降水季节性对区域中大陆水电气候的影响，并确定海洋 - 大气过程的潜在作用。具体而言，研究人员将检验三个假设。 1）在过去的2000年中，美国中部美国中部的多年至百年氢气气候变化的特征是东西氢化气候偶极子，其铰链线位于大平原和中西部之间的铰链线。 2）氢气候偶极子的变化是由大气循环驱动的，类似于太平洋北美模式，该模式改变了季节性降水模式。 3）中大陆氢化气候和大气循环异常主要由太平洋盆地大气 - 海洋过程控制。这项研究的关键组成部分是对本科生和研究生的教育和培训，同时通过招募和支持妇女和代表性不足的科学少数群体来积极努力提高STEM领域的多样性。该项目将直接支持一名博士学位，2个MSC和4名本科生，而其他资料来源的其他几个支持也将有助于。由于将科学翻译给公众是任何有效的研究项目的关键组成部分，因此研究人员及其机构将开展外展活动，包括开发4至9年级学生的教育模块，专注于1）中西部气候，2）古气候重建技术，以及3）水资源可变性。该模块将由IUPUI的地球与环境科学中心开发和实施，并公开供其他教育工作者使用。研究人员将与印第安纳州立博物馆合作，将这些项目的结果纳入有关美国中洲原住民的互动展览中。该奖项反映了NSF的法定任务，并被认为是值得通过基金会的知识分子和更广泛影响的评估审查标准来通过评估来获得支持的。