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

热带太平洋对全球气候影响很大。这种影响在厄尔尼诺-南方涛动(ENSO)事件期间表现得很明显。热带太平洋ENSO的年际变化导致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。热带太平洋十年至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，要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况和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条件的影响鲜为人知。这限制了我们预测未来几十年气候的能力。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、树轮和冰芯等地质档案中的气候记录来填补。该项目将使用赤道中部太平洋珊瑚的精确年代记录，以产生大约1800年以来的海洋温度记录。这一温度记录将与气候模型模拟进行比较，以了解观察到的海洋温度的趋势和变化，以及它们对气候的影响。该项目将支持研究生和本科生的研究。该项目旨在利用基里蒂马蒂岛(2N，157W)现代珊瑚和化石珊瑚的配对氧同位素和微量元素测量，生成多达20条新的热带太平洋中部热带太平洋1800-1950年期间每月分辨海表面温度和水文变化的精确日期记录。拟议的工作建立在最近以珊瑚为基础的气候重建的“整体”办法取得成功的基础上，这种办法使得能够编制高保真的、按月分辨的热带太平洋气候记录，并明确量化不确定性，其基础是对照近几十年的仪器气候记录对现代珊瑚进行校准。此外，应用成对珊瑚d18O和锶/钙分析可以单独确定过去几个世纪的温度和水文趋势--填补关键数据空白，并允许与先进的海洋状况再分析产品进行详细的数据模型相互比较。拟议的工作包括应用各种战略来评估珊瑚气候记录的稳健性，包括对样本保存的详细分析，因为如果没有被发现，地球化学变化可能会给珊瑚气候重建带来重大的人工制品。如果成功，这项拟议的工作将提供一个蓝图，利用存在于许多海洋岛屿上的大片珊瑚碎石场的样本，将短暂的仪器气候记录扩展到整个太平洋。这一奖励反映了NSF的法定使命，并通过使用基金会的智力优势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.