RAPID Collaborative Research: Ground Truthing Coral Proxy Reconstructions of ENSO by Observing the 2014-15 El Nino

RAPID 协作研究：通过观测 2014-15 厄尔尼诺现象对 ENSO 进行地面实况珊瑚代理重建

• 批准号: 1446343
• 负责人: Kim Cobb
• 金额: $ 2.66万
• 依托单位: Georgia Tech Research Corporation
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 2014
• 资助国家: 美国
• 起止时间: 2014-07-01 至 2015-06-30
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=1446343&HistoricalAwards=false
• 关键词: RAPID; Collaborative; Research; Ground; Truthing

The El Nino/Southern Oscillation (ENSO) is the dominant source of inter-annual climate variability in the world and it impacts a variety of important economic sectors in the U.S. and around the world like fisheries, agriculture and water resource management. Thus, it is vital to understand how its properties (magnitude, rate of occurrence, duration) might change under future climates. State-of-the-art climate model projections show no agreement on the direction of future ENSO changes and instrumental records are too short to constrain the statistics of ENSO, making it imperative to use paleoclimate reconstructions to establish a long-term observational context for ENSO. Record of isotopic oxygen in corals collected in the central equatorial Pacific suggests that ENSO may strengthen in the future, but a major caveat remains: the physics of the ENSO influence on the properties of corals is poorly understood, as their chemical composition is affected by water exchange in the reef environment, as well as by precipitation. This project will collect in situ observations of physical conditions (temperature, salinity,and currents) and isotopic variations (in seawater, precipitation, and corals) during a rapidly approaching event: the El Nino expected during winter 2014-15. The proposed dataset will be used to validate ongoing modeling work, create a reanalysis of the 2014-15 El Nino event with the goal of improving the interpretation of reconstructed records of past El Ninos. A post-doctoral fellow will lead the project and in the process will expand her technical and scientific expertise.Tehcnical description: Paleoclimate information from coral isotopic oxygen (Oxygen 18) is a critical source of data on past climate variability, providing an observational baseline for projections of future changes to ENSO. However, ENSO affects Oxygen 18 through advective shifts, topographically-induced upwelling, and surface fluxes: this makes it extremely difficult to use Oxygen 18 records for quantitative comparisons with instrumental records or climate model output. An ongoing NSF-funded study using a newly developed, isotope-enabled version of the Regional Ocean Modeling System (isoROMS) has shown that the spatial scale of processes affecting Oxygen 18 may be quite small, as proxy collection sites lie in nearshore reef environments. Thus, obtaining additional in situ data is critical for validating the isoROMS result and improving dynamical understanding. The El Nino event expected during winter 2014-15 provides a unique opportunity to collect both in situ physical oceanographic information and isotopic measurements, which combined with the isoROMS work would provide the most complete and dynamically consistent characterization of the El Nino influence on proxy sites to date. The results would greatly advance interpretation of existing oxygen 18 records as well as climate model validation efforts. The proposed dataset would be a major asset for studies of coral paleoclimate reconstruction as well as climate model validation. This project is led by an early career female scientist, and will add an observational component to the research she is conducting under an NSF Ocean Sciences postdoctoral fellowship. Collaborations with colleagues from a range of disciplines will be facilitated by this study. Finally, the results will be used to develop a reanalysis of the 2014-15 El Nino event, which will be provided as a resource for the community.

厄尔尼诺/南方涛动 (ENSO) 是世界年际气候变化的主要来源，它影响美国和世界各地的各种重要经济部门，如渔业、农业和水资源管理。因此，了解其特性（强度、发生率、持续时间）在未来气候下可能发生的变化至关重要。最先进的气候模型预测显示，对于未来 ENSO 变化的方向没有达成一致，而且仪器记录太短，无法限制 ENSO 的统计数据，因此必须利用古气候重建来建立 ENSO 的长期观测背景。在赤道中太平洋收集的珊瑚中的同位素氧记录表明，ENSO 未来可能会加强，但仍然存在一个重大警告：ENSO 对珊瑚特性影响的物理原理知之甚少，因为它们的化学成分受到珊瑚礁环境中水交换以及降水的影响。该项目将收集在快速逼近的事件（预计在 2014-15 年冬季发生的厄尔尼诺现象）期间物理条件（温度、盐度和洋流）和同位素变化（海水、降水和珊瑚）的现场观测。拟议的数据集将用于验证正在进行的建模工作，对 2014-15 年厄尔尼诺事件进行重新分析，目的是改进对过去厄尔尼诺现象重建记录的解释。一名博士后研究员将领导该项目，并在此过程中扩展她的技术和科学专业知识。技术描述：来自珊瑚同位素氧（氧 18）的古气候信息是过去气候变化的重要数据来源，为预测 ENSO 未来变化提供了观测基线。然而，ENSO 通过平流位移、地形引起的上升流和地表通量影响氧气 18：这使得使用氧气 18 记录与仪器记录或气候模型输出进行定量比较变得极其困难。一项由 NSF 资助的正在进行的研究使用新开发的同位素版本的区域海洋建模系统 (isoROMS) 表明，影响氧 18 的过程的空间规模可能相当小，因为代理收集点位于近岸珊瑚礁环境中。因此，获得额外的原位数据对于验证 isoROMS 结果和提高动力学理解至关重要。预计在 2014-15 年冬季发生的厄尔尼诺事件为收集原位物理海洋信息和同位素测量提供了独特的机会，这与 isoROMS 工作相结合将提供迄今为止厄尔尼诺对代理站点影响的最完整和动态一致的表征。这些结果将极大地推进对现有氧 18 记录的解释以及气候模型验证工作。拟议的数据集将成为珊瑚古气候重建和气候模型验证研究的主要资产。该项目由一位早期职业女性科学家领导，将为她在美国国家科学基金会海洋科学博士后奖学金下进行的研究增加观察部分。这项研究将促进与不同学科同事的合作。最后，结果将用于对 2014-15 年厄尔尼诺事件进行重新分析，并将其作为社区资源提供。