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

厄尔尼诺/南方涛动（ENSO）是全球年际气候变率的主要来源，它影响着美国和世界各地的许多重要经济部门，如渔业、农业和水资源管理。因此，了解其性质（大小、发生率、持续时间）在未来气候下可能发生的变化是至关重要的。最先进的气候模式预估显示，未来ENSO变化的方向不一致，仪器记录太短，无法限制ENSO的统计，因此必须使用古气候重建来建立ENSO的长期观测背景。在赤道太平洋中部收集的珊瑚中同位素氧的记录表明，ENSO在未来可能会加强，但仍然存在一个重大警告：ENSO对珊瑚特性的物理影响知之甚少，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。该项目将收集快速逼近事件期间的物理条件（温度、盐度和洋流）和同位素变化（海水、降水和珊瑚）的现场观测数据：预计2014- 2015年冬季将出现厄尔尼诺现象。该数据集将用于验证正在进行的建模工作，创建2014-15年厄尔尼诺事件的重新分析，目的是改进对过去厄尔尼诺现象重建记录的解释。一名博士后将领导该项目，并在此过程中扩大她的技术和科学专长。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率数据的重要来源，为预测ENSO的未来变化提供了观测基线。然而，ENSO通过平流移动、地形诱导的上升流和地表通量影响氧18：这使得使用氧18记录与仪器记录或气候模式输出进行定量比较变得极其困难。一项由美国国家科学基金会资助的研究正在进行中，该研究使用了新开发的同位素支持版本的区域海洋模拟系统（isoROMS），该研究表明，影响氧18的过程的空间尺度可能相当小，因为代用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2014- 2015年冬季的厄尔尼诺事件为收集现场物理海洋学信息和同位素测量提供了一个独特的机会，这些信息与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特征。该结果将极大地促进对现有氧18记录的解释以及气候模型验证的努力。该数据集将成为珊瑚古气候重建和气候模型验证研究的重要资产。该项目由一位早期职业女性科学家领导，并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一个观察部分。这项研究将促进与各学科同事的合作。最后，研究结果将用于对2014- 2015年厄尔尼诺事件进行重新分析，并作为社区资源提供。

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.