Collaborative Research: P2C2--Speleothem Constraints on Seasonal Hydroclimate Variability in Mainland Southeast Asia since the Late Pleistocene

合作研究：P2C2--晚更新世以来东南亚大陆洞穴水文季节变化的制约

• 批准号: 2103129
• 负责人: Kathleen Johnson
• 金额: $ 60.77万
• 依托单位: University of California-Irvine
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 2021
• 资助国家: 美国
• 起止时间: 2021-07-01 至 2024-06-30
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=2103129&HistoricalAwards=false
• 关键词: Collaborative; Research; P2C2; Speleothem; Constraints

This project aims to characterize the Asian summer and winter monsoon circulation and local hydroclimate across Mainland Southeast Asia (MESA) during the last ~45 thousand years using a suite of speleothem records from caves that extend across a critical geographical divide between Laos and Vietnam, two countries with very distinct seasonal rainfall climatologies. The overarching goal of this work is to explore the dynamic response of summer and winter Asian monsoon variability to changing external drivers, such as insolation, and internal climate variability which will contribute to improved understanding of large-scale hydrological variability in a vulnerable region. Specifically, the researchers will develop a new set of past climate records utilizing multiple environmental tracers (Carbon and Oxygen isotopes, trace elements such as Magnesium/Calcium, radiocarbon) in precisely dated speleothems spanning at least the last ~45 thousand years. Additionally, a detailed cave monitoring program will aid the interpretation of data obtained from the speleothems. The results will be integrated with other regional and global records of past climate variability and state-of-the-art climate model simulations to diagnose the dominant mechanisms driving hydroclimate variability on sub-decadal to millennial timescales in the MESA region. The research will address the following specific objectives: (1) Determine the summer and fall/winter response of MSEA hydroclimate to orbital and millennial-scale forcing, (2) Determine the response of MSEA hydroclimate to decadal to multidecadal scale sea surface temperature variability, and (3) Synthesize data with other available records to elucidate the spatiotemporal patterns of MSEA hydroclimate, which, combined with paleoclimate model analyses, will allow us investigation of the dynamical mechanisms underlying summer and fall/winter monsoon variability. Speleothem oxygen isotope records from three study sites will serve as a proxy for summer monsoon intensity, dominated by the degree of upstream rainout over the Indian Ocean and trace element measurements will provide robust evidence for past variations in local water balance at each cave site, with Laos sites recording summer rainfall and Vietnam sites recording fall/winter rainfall.The potential Broader Impacts include a better understanding of the monsoon dynamics and related hydroclimate in a vulnerable region by generating quantitative and well-dated multi-millennial climate records from speleothems. The project will provide scientific training, mentorship and professional development for several undergraduate (including summer research experience) and one graduate (Ph.D.) students, as well as one postdoctoral researcher at three universities including two minority serving institutions. Additionally, the project will support an early career scientist. The results of the project will be part of ongoing and newly developed public outreach activities both in The US and the study region (Laos/Vietnam) involving students and postdocs. The project will also foster international and transdisciplinary collaborations including with local communities.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.

该项目旨在描述亚洲夏季和冬季季风环流以及东南亚大陆（梅萨）在过去约4.5万年的当地水文气候，使用一套洞穴记录，这些洞穴跨越老挝和越南之间的关键地理分界线，这两个国家具有非常不同的季节性降雨气候。这项工作的总体目标是探索夏季和冬季亚洲季风变化的动态响应不断变化的外部驱动因素，如日照，和内部气候变化，这将有助于提高对大规模的水文变化的理解在一个脆弱的地区。具体来说，研究人员将利用多种环境示踪剂（碳和氧同位素，镁/钙等微量元素，放射性碳）开发一套新的过去气候记录，这些记录至少跨越了过去4.5万年。此外，一个详细的洞穴监测计划将有助于解释从洞穴沉积物获得的数据。研究结果将与其他区域和全球过去气候变率记录和最先进的气候模式模拟相结合，以诊断在梅萨地区近十年至千年时间尺度上驱动水文气候变率的主要机制。这项研究将涉及以下具体目标：（1）确定夏季和秋季/冬季MSEA水文气候对轨道和千年尺度强迫的响应，（2）确定MSEA水文气候对十年到多年尺度海面温度变率的响应，以及（3）将数据与其他可用记录相结合，以阐明MSEA水文气候的时空模式，结合古气候模式分析，将使我们能够调查的动力机制，夏季和秋季/冬季风的变化。来自三个研究地点的洞穴沉积物氧同位素记录将作为夏季季风强度的代理，主要由印度洋上游降雨的程度决定，微量元素测量将为每个洞穴地点过去当地水平衡的变化提供强有力的证据，老挝观测点记录了夏季降雨量，越南观测点记录了秋季降雨量。潜在的更广泛的影响包括通过从洞穴沉积物中产生定量的和日期明确的多千年气候记录，更好地了解脆弱地区的季风动力学和相关水文气候。该项目将为几名本科生（包括夏季研究经验）和一名研究生（博士）提供科学培训，指导和专业发展。在三所大学，包括两个少数民族服务机构，有一名博士后研究员。此外，该项目将支持一个早期的职业科学家。该项目的成果将成为美国和研究区域（老挝/越南）正在进行的和新开发的公共宣传活动的一部分，涉及学生和博士后。这个奖项反映了NSF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。