Reconstructions of central tropical Pacific climate during the 19th to early 20th centuries

热带太平洋对全球气候有很大的影响。这种影响在厄尔尼诺Niño-Southern涛动（ENSO）事件中表现明显。热带太平洋ENSO的年际变化推动了全球天气模式的巨大变化，包括可能导致洪水、干旱和野火的区域极端降雨。热带太平洋每十年的变化也对全球气候产生重大影响，包括全球变暖的速度和模式。因此，为了预测未来全球气候和极端天气的变化，我们必须了解热带太平洋的长期状态和ENSO变率的变化。然而，自工业革命开始以来，人类活动对热带太平洋环境的影响却鲜为人知。这限制了我们预测未来几十年气候变化的能力。在1950年之前，赤道太平洋中部的直接气候观测很少，但这一数据缺口可以通过珊瑚、树木年轮和冰芯等地质档案的气候记录来填补。该项目将使用赤道太平洋中部精确确定年代的珊瑚记录，生成自1800年以来的海洋温度记录。这一温度记录将与气候模式模拟结果进行比较，以了解观测到的海洋温度趋势和变化及其对气候的影响。该项目将支持研究生和本科生的研究。它还将制作针对K-12学生和教师的宣传视频。该项目旨在通过对Kiritimati岛（2N, 157W）的现代和化石珊瑚的配对氧同位素和微量元素测量，生成最多20个新的精确日期记录，这些记录记录了1800-1950年期间热带太平洋中部的海面温度和水文变化。拟议的工作建立在最近基于珊瑚的气候重建的“集合”方法的成功基础上，该方法允许开发高保真度、每月分辨率的热带太平洋气候记录，并明确量化不确定性，其基础是根据近几十年来的仪器气候记录对现代珊瑚进行校准。此外，配对珊瑚d18O和Sr/Ca分析的应用允许单独识别过去几个世纪的温度和水文趋势-填补关键数据空白，并允许详细的数据模型与先进的海洋状态再分析产品进行相互比较。拟议的工作包括应用各种策略来评估基于珊瑚的气候记录的稳健性，包括对样本保存的详细分析，因为地球化学变化如果未被发现，可能会在基于珊瑚的气候重建中引入重要的人工制品。如果成功，这项拟议的工作将为扩展整个太平洋的短期仪器气候记录提供蓝图，利用来自许多海洋岛屿上广泛的珊瑚碎石场的样本。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。

The tropical Pacific Ocean has a strong influence on global climate. This influence is evident during El Niño-Southern Oscillation (ENSO) events. Interannual ENSO variations in the tropical Pacific drive large shifts in global weather patterns, including regional rainfall extremes that can lead to floods, droughts, and wildfires. Decade-to-decade changes in the tropical Pacific also have large impacts on global climate, including the rate and pattern of global warming. Thus, to predict future changes in global climate and weather extremes we must know about the long-term state of the tropical Pacific and about changes in ENSO variability. However, the impacts of human activities since the start of the Industrial Revolution on conditions in the tropical Pacific are poorly known. This limits our ability to predict climate for the coming decades. Direct climate observations from the central equatorial Pacific are sparse prior to 1950, but this data gap can be filled by records of climate from geologic archives such as corals, tree rings, and ice cores. This project will use precisely dated coral records from the central equatorial Pacific to produce a record of ocean temperature since about 1800. This temperature record will be compared with climate model simulations to understand the observed trends and variability in ocean temperature, and their impact on climate. The project will support research by both graduate and undergraduate students. It will also develop outreach videos aimed at K-12 students and teachers.The project aims to generate up to 20 new precisely-dated records of monthly-resolved sea-surface temperature and hydrological variability in the central tropical Pacific during the period from 1800-1950CE using paired oxygen isotope and trace element measurements in modern and fossil corals from Kiritimati Island (2N, 157W). The proposed work builds on the success of recent "ensemble" approaches to coral-based climate reconstruction that allow for the development of high-fidelity, monthly-resolved records tropical Pacific climate with explicit quantification of uncertainties, grounded in calibration of modern corals against instrumental climate records over recent decades. Moreover, the application of paired coral d18O and Sr/Ca analyses allows for the separate identification of temperature and hydrological trends over the last centuries - filling critical data gaps and allowing for detailed data-model intercomparison with advanced ocean state reanalyses products. The proposed work includes the application of a wide variety of strategies to assess the robustness of the coral-based climate records, including detailed analysis of sample preservation, as geochemical alteration can introduce significant artifacts into coral-based climate reconstructions if it goes undetected. If successful, the proposed work would provide a blueprint for the extension of the short instrumental climate record throughout the Pacific Ocean, utilizing samples from extensive coral rubble fields that are present on many ocean islands.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.