Collaborative Research: Reconstructing Climate Linkages Across the Tropical Oceans Over the Last Millennium

合作研究：重建过去千年热带海洋的气候联系

• 批准号: 2202793
• 负责人: Julia Cole
• 金额: $ 53.9万
• 依托单位: Regents of the University of Michigan - Ann Arbor
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 2022
• 资助国家: 美国
• 起止时间: 2022-06-15 至 2025-05-31
• 项目状态: 未结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=2202793&HistoricalAwards=false
• 关键词: Collaborative; Research; Reconstructing; Climate; Linkages

Year-to-year changes in the temperatures of the tropical oceans impact climate and weather around the world. The clearest example of this is the El Niño-Southern Oscillation (ENSO) system in the tropical Pacific. Warming and cooling patterns related to ENSO have major effects on droughts, floods, and tropical storms. The temperature of the tropical Atlantic and Indian also affects weather in the same types of ways. Not only that, the three ocean basins can interact with each other since the atmosphere connects them all. For example, warming in the tropical Atlantic tends to lead to wind patterns that then cool off the tropical Pacific. This means that to predict how climate variations may change in the future, one must understand the connections between the tropical oceans. However, those relationships are known to change over long timescales (multiple decades), and temperature records are short and scarce in the tropics. As a result, this problem is difficult to study with traditional observations (e.g. thermometers). Instead, this project will produce records of temperature using the geochemistry of long-lived corals. By comparing data from corals in the Pacific, Atlantic, and Indian oceans, this research will show how these oceans have interacted over the past several centuries. Comparison of the 20th century with previous centuries will reveal the influence of recent warming. This work explores whether these patterns appear in the climate models used to understand future climate change, and what physical processes are involved. Several different model groups will be used for comparison. Students and postdocs will also participate in this research. Finally, the project will develop training materials to make data and model results more accessible to those without a highly technical background. Interannual to multidecadal variability in the tropical oceans drives climate extremes that impact natural and human systems around the world. The equatorial Pacific ENSO system is particularly important, and recent work highlights that Atlantic and Indian ocean variability impact the recurrence and intensity of ENSO extremes. Multiple mechanisms drive these interactions, which are affected by natural and anthropogenic forcing. Yet the relative importance of each mechanism remains unknown, as does the time history of the inter-basin teleconnections. Closing this knowledge gap is fundamental to understanding how inter-basin interactions are influenced by external forcing and improving the accuracy of future model projections in the tropics and beyond. This study will create new paleoclimate records of sea surface temperature (SST) using the elemental and isotopic composition of coral skeletal material, in cores from centuries-old colonies in the Tropical North Atlantic (TNA) and Western Indian Ocean (WIO). These data will be combined with published data to reconstruct pre-instrumental SST for these regions and assess inter-basin interactions. The study will also explore the relationship of these patterns to external forcing. The project will evaluate the degree to which interbasin interactions are manifest across relevant model simulations. Insights from coral proxies will be explored with the ensemble of isotope-enabled Last Millennium Ensemble simulations: the study will analyze existing iCESM output, including ‘single forcing’ experiments to diagnose individual external influences on climate and isotopic variability, and perform targeted sensitivity experiments isolating the isotopic signatures associated with particular dynamical mechanisms.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.

热带海洋温度的逐年变化影响着世界各地的气候和天气，最明显的例子是热带太平洋的厄尔尼诺南方涛动（ENSO）系统。热带大西洋和印度洋的温度也以同样的方式影响天气，不仅如此，这三个海洋盆地还可以相互作用，因为大气将它们连接起来。例子，热带大西洋变暖导致风型趋向使热带太平洋变冷，这意味着要预测未来气候变化可能如何变化，我们必须了解热带海洋之间的联系。长时间尺度（数十年）的变化，而热带地区的温度记录又短又稀缺，因此，很难用传统观测（例如温度计）来研究这个问题，相反，该项目将使用地球化学来产生温度记录。的通过比较太平洋、大西洋和印度洋珊瑚的数据，这项研究将显示这些海洋在过去几个世纪中如何相互作用，并将 20 世纪与之前的几个世纪进行比较，揭示近期变暖的影响。这项工作探讨了这些模式是否出现在用于了解未来气候变化的气候模型中，以及涉及哪些物理过程。学生和博士后也将参与这项研究。将开发培训材料使那些没有高技术背景的人更容易获得数据和模型结果热带海洋的年际到数十年的变化导致了影响世界各地自然和人类系统的极端气候，最近的工作强调了这一点。大西洋和印度洋的变化影响着 ENSO 极端事件的发生和强度，这些相互作用受到自然和人为强迫的影响，但每种机制的相对重要性仍然未知，跨盆地的时间历史也是如此。缩小这一知识差距对于了解外部强迫如何影响流域间相互作用以及提高热带地区及其他地区未来模型预测的准确性至关重要。热带北大西洋 (TNA) 和西印度洋 (WIO) 数百年历史珊瑚礁的珊瑚骨骼材料的元素和同位素组成这些数据将与已发布的数据相结合来重建。该研究还将探讨这些模式与外部强迫的关系，并评估相关模型模拟中流域间相互作用的表现程度。通过同位素支持的上个千年集合模拟的集合进行探索：该研究将分析现有的 iCESM 输出，包括“单一强迫”实验，以诊断个体外部对气候和同位素变化的影响，并执行有针对性的敏感性实验，分离与特定动力机制相关的同位素特征。该奖项反映了 NSF 的法定使命，并通过使用基金会的智力优点和更广泛的影响审查标准进行评估，被认为值得支持。