NSFGEO-NERC: Collaborative Research: Understanding the Drivers of Inert Gas Saturation to Better Constrain Ice Core-Derived Records of Past Mean Ocean Temperature

该奖项的全部或部分资金来自《2021年美国救援计划法案》(公法117-2)。全球海洋的综合热含量是了解地球能量平衡的基本气候变量。对全球能源预算过去变化的准确估计对于了解地球系统固有的敏感性至关重要。该项目将通过对海洋中溶解气体进行计算机模拟来解决这些估计的准确性问题。通过分析这些模拟的结果，该团队的目标是改进基于冰芯的海洋热含量重建，这些重建依赖于对保存在冰芯中的古老气泡中气体(氙气、氪和氮)的测量。该项目旨在提供末次冰盛期期间冰川海洋中氙气、氪和氮的饱和异常的第一次估计和不确定范围。最近的分析进展使得能够以足够的精度测量冰芯中氙气与氮和氪与氮的比率，以解决这些比率在全大气中的变化，反映出全球海洋在0.1摄氏度水平上的变暖和变冷。然而，使用惰性气体测量来定量限制过去的海洋热含量，需要对这些气体的全球海洋饱和状态的长期变化做出假设，这仍然是一个完全悬而未决的问题。因此，该团队将使用传输矩阵法进行生物地球化学示踪模拟。他们将利用维多利亚大学地球系统气候模型对冰川海洋中的氧气和二氧化碳进行一系列先前进行的模拟，以定量限制惰性气体饱和状态下冰川-间冰期的变化，并了解其物理驱动因素。此外，该团队将增加使用第二个模型(麻省理工学院全球环流模型)的独立实验，并在未来进行几个变暖实验，以考虑地球系统正在发生的变化可能如何影响海气物理传输。最后，该研究小组将重新评估现有的冰芯惰性气体记录，以对最后一次冰川盛期期间海洋热含量的变化以及最后一次冰川消融期间的突然变暖做出最佳估计。这是一个由美国国家科学基金会地球科学局(NSF/GEO)(美国参与者)和英国自然环境研究理事会(UKRI/NERC)通过NSF/GEO-NERC牵头机构协议共同资助的项目。该协定允许美国和英国提交一个单一的联合提案，并由该机构进行同行审查，该机构的调查员在预算中所占比例最大。在成功联合确定奖项后，每个机构将为预算的比例以及与其自身调查人员和工作部分相关的调查人员提供资金。NSF奖项全部或部分根据《2021年美国救援计划法案》(公法117-2)提供资金。该奖项反映了NSF的法定使命，并已通过使用基金会的智力价值和更广泛的影响审查标准进行评估，被认为值得支持。

This award is funded in whole or in part under the American Rescue Plan Act of 2021 (Public Law 117-2). The integrated heat content of the global ocean is a fundamental climate variable for understanding Earth’s energy balance. Accurate estimates of past changes in the global energy budget are essential for understanding the inherent sensitivities of the Earth system. This project will address the accuracy of these estimates by carrying out computer simulations of dissolved gases in the ocean. By analyzing the outcomes of these simulations, the team aims to refine ice-core-based reconstructions of ocean heat content that rely on measurements of gases (Xenon, Krypton, and Nitrogen) in ancient air bubbles preserved in ice cores. The project aims to produce the first estimates and uncertainty ranges of saturation anomalies of Xenon, Krypton, and Nitrogen in the glacial ocean during the Last Glacial Maximum. Recent analytical advances have permitted measurement of ratios of Xenon to Nitrogen and Krypton to Nitrogen in ice cores at sufficient precision to resolve whole-atmosphere changes in these ratios that reflect warming and cooling of the global ocean at the 0.1ºC level. However, to quantitatively constrain past ocean heat content using inert gas measurements requires assumptions about long-term changes in the global ocean saturation state of these gases, which remains an entirely open problem. Consequently, the team will use the Transport Matrix Method for biogeochemical tracer simulations. They will build on a suite of previously conducted simulations of oxygen and carbon dioxide in the glacial ocean with the University of Victoria Earth System Climate Model to quantitatively constrain the glacial-interglacial change in inert gas saturation state and understand its physical drivers. In addition, the team will add independent experiments using a second model (the MIT global circulation model) and carry out several future warming experiments to consider how ongoing changes in the Earth system may affect physical air-sea gas transfer. Finally, the team will reevaluate existing ice-core inert gas records to produce best estimates of changes in ocean heat content during the Last Glacial Maximum and periods of abrupt warming throughout the last deglaciation. This is a project that is jointly funded by the National Science Foundation’s Directorate of Geosciences (NSF/GEO) (U.S. participants) and the Natural Environment Research Council (UKRI/NERC) of the United Kingdom (UK) via the NSF/GEO-NERC Lead Agency Agreement. This Agreement allows a single joint US/UK proposal to be submitted and peer-reviewed by the Agency whose investigator has the largest proportion of the budget. Upon successful joint determination of an award, each Agency funds the proportion of the budget and the investigators associated with its own investigators and component of the work.The NSF award is funded in whole or in part under the American Rescue Plan Act of 2021 (Public Law 117-2)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.