Collaborative Research: Multi-century hydrologic and NAO variability in the tropical Western Atlantic - A Marine NAO Synthesis

了解北大西洋地区的气候变化对美国东部、西欧和其他地区的社会至关重要。特别是北大西洋涛动（NAO），这是一个改变海面温度的气压系统，影响美国和欧洲人口密集中心的陆地温度、干旱和风暴路径。虽然我们现在可以每年测量NAO，但对它的长期行为知之甚少，或者它的行为在未来会如何变化。该项目将利用加勒比海南部多巴哥岛的珊瑚生成过去气候变化的记录，该地区对新大西洋的影响特别敏感。巨型脑珊瑚的岩心将用水肺采集，对岩心的化学分析将用于生成过去几个世纪以来的温度、盐度和降雨量的月度历史。这些气候记录将有助于深入了解热带大西洋气候变异的时空格局，特别是与NAO有关的大尺度过程。这项国际合作将支持特立尼达和多巴哥大学的一名研究生前往美国国家卫生研究院和世界卫生组织，接受珊瑚x射线和地球化学分析方面的指导和培训。该项目还包括积极参与AMNH和WHOI的教育和推广计划，包括行星地球大厅，这是AMNH参观者和学校团体选择的五大大厅之一。该项目将通过生成高分辨率（每月一次）、多世纪的南加勒比海水文特性记录（包括海面温度（SST）、海面盐度（SSS）和当地河流径流），直接为美国国家科学基金会的气候变化古视角（P2C2）目标做出贡献。这项研究将收集来自多巴哥东北部的两个多世纪珊瑚岩心，并随后构建古气候记录，以解决完整的季节周期问题，这对于识别诸如北大西洋涛动（NAO）等区域强迫的特征至关重要。锶-钙（Sr/Ca）比值用于重建海表温度，氧同位素（del18O）比值与Sr/Ca比值用于重建海表温度。最后，钡钙（Ba/Ca）比值将产生陆地输入和河流径流的记录。本研究将针对Siderastrea和Colpophyllia珊瑚物种，这些物种以前被证明可以用骨骼地球化学代理忠实地记录气候变量。从这个敏感地点重建冬季海温将捕捉到NAO的长期变化，并与大西洋和红海现有的NAO和海温记录进行比较，将有助于调查过去几个世纪海洋NAO信号的区域一致性和空间平定性变化。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。

Understanding climate variability in the North Atlantic region is critical to society in the Eastern United States, Western Europe and beyond. In particular, the North Atlantic Oscillation (NAO), an atmospheric pressure system that alters sea surface temperatures, influences land temperature, drought, and storm tracks across the dense population centers of the US and Europe. While we can now measure the NAO each year, little is known about its longer-term behavior, or how its behavior may change in the future. This project will generate records of past climate change using corals from the island of Tobago in the southern Caribbean Sea, a region especially sensitive to the effects of the NAO. Drill cores of giant brain corals will be taken using SCUBA, and chemical analysis of the cores will be used to generate monthly histories of temperature, salinity and rainfall that extend back over the past several centuries. These climate records will provide insights into the temporal and spatial patterns of tropical Atlantic climate variability, particularly the large-scale processes associated with the NAO. This international collaboration will support a graduate student from The University of Trinidad and Tobago to travel to AMNH and WHOI for mentorship and training in coral x-ray and geochemical analysis. The project also includes active participation in the educational and outreach programs at both AMNH and WHOI, including the Hall of Planet Earth, among the top five halls chosen by AMNH visitors and school groups.This project will contribute directly to NSF's Paleo Perspectives on Climate Change (P2C2) goals by generating high resolution (monthly), multi-century long records of the hydrologic properties in the southern Caribbean Sea, including sea surface temperature (SST), sea surface salinity (SSS) and local river runoff. The study will result in collection of two multi-century coral drill cores from northeastern Tobago, and subsequently the construction of paleoclimate records that resolve the full seasonal cycle, critical for identifying signatures of regional forcing such as the North Atlantic Oscillation (NAO). Strontium-calcium (Sr/Ca) ratios will be used to reconstruct SST, and oxygen isotope (del18O) ratios together with Sr/Ca will be used to reconstruct SSS. Finally, barium-calcium (Ba/Ca) ratios will yield records of terrestrial input and river runoff. This investigation will target Siderastrea and Colpophyllia coral species previously shown to faithfully record climatic variables with skeletal geochemical proxies. A winter-season SST reconstruction from this sensitive site will capture long-term NAO variability, and comparison with existing records of the NAO and SST from the Atlantic and Red Sea will allow investigation of regional coherence and changes in the spatial stationarity of the marine NAO signal over the past few centuries.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.