Drivers and Impacts of North Atlantic freshwater and heat fluxes unsettling modern-day climate (DIMSUM)

这是一个由美国国家科学基金会地球科学理事会（NSF/GEO）和英国国家环境研究委员会（NERC）通过NSF/GEO-NERC牵头机构协议共同资助的项目。该协议允许美国/英国提交一份联合提案，并由其调查员拥有最大比例预算的机构进行同行评审。在成功地共同确定一个奖项推荐后，每个机构资助预算的比例，以支持各自国家机构的科学家。北极与北大西洋的热淡水交换影响着大尺度的北大西洋和全球气候。复杂的相互作用和反馈跨越多个时空尺度，从短期、局地到多年代际，跨越大洋盆地。因此，准确了解影响进入北美的热量和淡水通量的机制，以及随后形成表面特性的海洋混合，对于评估北美快速气候变化的风险至关重要。该项目将使用一套全面的基于观测和模型的产品和工具，以显著提高我们对NA热量和FW变化的理解，阐明驱动因素，揭示大气反馈，并探索对更大范围天气和气候的后续影响。了解气候变化和天气模式之间错综复杂的关系具有重要的社会意义。该项目通过揭示系统内一个主要但不确定的组成部分的行为，在应对这一挑战方面发挥着关键作用，最终有助于制定更明智的气候适应和减缓战略。该研究小组的特点是女性科学家和两名pi （Lenn & Nguyen）的比例很高，他们来自历史上在地球科学领域代表性不足的全球南方民族。该项目为早期职业女性科学家Pillar和Schulz （UT Austin）提供培训和领导机会。该项目将利用一套全面的基于观测和模型的产品和工具，特别是opsnap和RAPID系泊阵列，耦合高分辨率模型模拟和北极亚极地环流状态估计（ASTE），研究北极热量和FW变化的驱动因素和影响。ASTE是一种具有内置伴随能力的动态一致模型-数据综合，为研究NA动态和变异性的因果驱动提供了非常独特和强大的工具。将这些产品与新颖的统计工具和最先进的分析技术相结合，将有助于评估阵列上下游的变化机制，并评估其气候反馈，包括快速释放波弗特环流FW的潜在驱动因素和影响。该项目的三个研究目标是：(1)利用观测（例如，OSNAP和RAPID阵列，Argo，卫星衍生），模型数据综合（ASTE）和耦合模型，量化热量和FW预算；（O2）阐明驱动热量和FW预算变化和创造快速气候变化阈值的机制；（O3）评估海洋热量和FW变化对大尺度气候的影响，包括快速变化的风险。该方法的一个新方面是将水团转换预算的评估与势能诊断和伴随灵敏度映射配对。这些互补的观点只有在状态估计框架内才能共同获得，并将为远程强迫重塑NA水团分布和破坏对流不稳定的机制提供新的见解。此外，这项工作将揭示NA内部潜在的可预测性。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。

This is a project jointly funded by the National Science Foundation’s Directorate for Geosciences (NSF/GEO) and the National Environment Research Council (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 recommendation, each Agency funds the proportion of the budget that supports scientists at institutions in their respective countries.Exchanges between the Arctic and North Atlantic (NA) of heat and freshwater (FW) impact the large-scale NA and global climate. The complex interactions and feedbacks span many spatial and temporal scales from short-term and local to multi-decadal and across ocean basins. An accurate understanding of the mechanisms impacting heat and FW fluxes into the NA, and subsequent ocean mixing that sets surface properties, is therefore of critical importance for assessing the risks of rapid NA climate change. This project will use a comprehensive set of observation- and model-based products and tools to significantly advance our understanding of NA heat and FW variations, elucidating drivers, exposing atmospheric feedbacks, and exploring subsequent impacts on larger-scale weather and climate. Understanding the intricate relationship between climate change and weather patterns is of paramount societal significance. This project plays a pivotal role in addressing this challenge by shedding light on the behavior of a major, yet uncertain, component within the system, ultimately contributing to more informed climate adaptation and mitigation strategies. The research team features a high proportion of female scientists and two PIs (Lenn & Nguyen) from historically-under-represented global south ethnic groups in geosciences. The project provides training and leadership opportunities for early-career female scientists Pillar and Schulz (UT Austin). This project will investigate drivers and impacts of heat and FW changes in the NA by capitalizing on a comprehensive set of observation- and model-based products and tools, in particular the OSNAP and RAPID mooring arrays, coupled high-resolution model simulations, and the Arctic Subpolar gyre sTate Estimate (ASTE). ASTE, a dynamically consistent model-data synthesis with inbuilt adjoint capability, provides a very unique and powerful tool for investigation of causal drivers of NA dynamics and variability. Combining these products with novel statistical tools and state-of-the-art analysis techniques, will help the assess mechanisms of change up- and downstream of the arrays and evaluate their climate feedbacks, including potential drivers and impacts of a rapid Beaufort Gyre FW release. The three research objectives of the project are (O1) Quantify heat and FW budgets, using observations (e.g., OSNAP and RAPID arrays, Argo, satellite-derived), model-data synthesis (ASTE) and coupled models; (O2) Elucidate mechanisms driving changes in heat and FW budgets and creating rapid climate change thresholds; (O3) Assess impacts of ocean heat and FW changes on large-scale climate, including the risk of rapid change. A novel aspect of this approach pairs assessment of watermass transformation budgets with potential energy diagnostics and adjoint sensitivity mappings. These complementary perspectives are jointly accessible only within the state estimation framework and will shed new insights into the mechanisms via which remote forcings can reshape NA watermass distribution and destabilize convection. Additionally, the work will reveal potential predictability within the NA.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.