Continental patterns of moisture anomalies associated with late Holocene mid-latitude megadroughts

与全新世晚期中纬度特大干旱相关的大陆水分异常模式

• 批准号: 0902441
• 负责人: Robert Booth
• 金额: $ 25.99万
• 依托单位: Lehigh University
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 2009
• 资助国家: 美国
• 起止时间: 2009-09-01 至 2013-08-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=0902441&HistoricalAwards=false
• 关键词: Continental; patterns; moisture; anomalies; associated

This award is funded under the American Recovery and Reinvestment Act of 2009 (Public Law 111-5).Warming temperatures associated with global climate change are expected to lead to more frequent and intense droughts in many mid-latitude regions. Understanding spatial patterns, magnitudes, and frequencies of past decadal-to-multidecadal droughts, and linkages of these patterns to dynamics of the coupled ocean-atmosphere system, is critical to assessing mechanisms and providing the foundation for risk assessment and prediction. There is a clear need for records of past hydroclimate variability in humid regions, where tree-ring based reconstructions lack hydroclimate sensitivity and/or temporal depth. This research produces a network of peatland-derived hydroclimate records spanning the past 3000 years in humid regions of North America. The network is used in conjunction with the tree-ring record of semi-arid regions and other drought-sensitive records to determine continental-scale footprints of past moisture anomalies. High-resolution analyses of testate amoebae, peat humification, and plant macrofossils provide detailed perspectives on hydroclimate variability. High-precision chronologies during significant mid-latitude drought episodes, particularly the Medieval Climate Anomaly (MCA), provide robust portrayals of moisture anomalies during these critical events. Data generation and synthesis is coupled with analyses of instrumental records of drought, precipitation, and sea-surface temperatures (SSTs) to test the hypothesis that widespread droughts like those during the MCA represented an amplification or unusual persistence of an observed mode of 20th century hydroclimate variability. Data-model comparisons and modeling experiments, constrained by proxy SST records, are used to assess the relative importance of Atlantic and Pacific Ocean influences on North American hydroclimate and the potential dynamic response of the climate system to changes in external forcing. The research provides spatial and temporal reconstructions of multidecadal hydroclimate variability in understudied regions, linking this variability to dynamics of the ocean-atmosphere system through synthesis of observational and modeling results, and identifying mechanisms and dynamics of the largest droughts to affect the North American continent in the last 3000 years. This work documents late Holocene droughts in regions conventionally assumed to have low drought risks, potentially transforming both scientific and societal perceptions.Results are disseminated through public lectures, a web site, teaching and advising at the University level, and organizational networks. Data is distributed through the NOAA paleoclimatology program, as well as other outlets. The project includes interdisciplinary training of graduate students and research experience for numerous undergraduates. The PI has a strong track record of recruitment of women. The PI incorporates project activities into course materials and seminars. The project renews a productive collaboration between the PI and the University of Wisconsin's CCR, taking advantage of the wealth of data created by the first mid-Holocene-to-present transient run of a fully coupled ocean-atmosphere-land model.

该奖项的资助依据《2009 年美国复苏与再投资法案》（公法 111-5）。与全球气候变化相关的气温升高预计将导致许多中纬度地区出现更加频繁和严重的干旱。了解过去十年到数十年干旱的空间模式、强度和频率，以及这些模式与海洋-大气耦合系统动态的联系，对于评估机制并为风险评估和预测提供基础至关重要。显然需要记录潮湿地区过去的水文气候变化，在这些地区，基于树木年轮的重建缺乏水文气候敏感性和/或时间深度。这项研究产生了北美潮湿地区过去 3000 年泥炭地水文气候记录网络。该网络与半干旱地区的树木年轮记录和其他干旱敏感记录结合使用，以确定过去湿度异常的大陆尺度足迹。对有遗嘱变形虫、泥炭腐殖化和植物大化石的高分辨率分析提供了关于水文气候变化的详细视角。重大中纬度​​干旱事件期间的高精度年表，特别是中世纪气候异常（MCA），为这些关键事件期间的水分异常提供了有力的描述。数据生成和合成与对干旱、降水和海面温度 (SST) 的仪器记录的分析相结合，以检验这样的假设：像 MCA 期间那样的大范围干旱代表了 20 世纪水文气候观测模式的放大或异常持续。可变性。受代理海表温度记录约束的数据模型比较和建模实验用于评估大西洋和太平洋对北美水文气候影响的相对重要性以及气候系统对外部强迫变化的潜在动态响应。该研究提供了所研究地区数十年水文气候变化的时空重建，通过综合观测和建模结果将这种变化与海洋大气系统的动态联系起来，并确定了影响北美大陆的最大干旱的机制和动态。过去3000年。这项工作记录了传统上认为干旱风险较低的地区的全新世晚期干旱，有可能改变科学和社会的看法。研究结果通过公共讲座、网站、大学层面的教学和建议以及组织网络进行传播。数据通过 NOAA 古气候学项目以及其他渠道分发。该项目包括研究生的跨学科培训和众多本科生的研究经验。 PI 在招聘女性方面有着良好的记录。 PI 将项目活动纳入课程材料和研讨会中。该项目延续了 PI 与威斯康星大学 CCR 之间富有成效的合作，利用了全新世中期至今瞬态运行完全耦合的海洋-大气-陆地模型所产生的丰富数据。