Collaborative Research: P2C2--Bridging the Gap from Northern Iberia to Northwest Africa to Reconstruct Atmospheric Dynamics and Hydroclimate for the Last 2,500 Years

地中海地区被认为是气候变化的热点地区。最近的观察，包括2017年火灾活动的增加，表明伊比利亚半岛的干旱已经在加剧。这个多机构的研究团队试图通过构建2500年的水文气候变化历史，为该地区正在进行和未来的气候变化提供空间和时间背景，这些历史来自于葡萄牙中部和南部洞穴中形成的对降水敏感的石笋。伊比利亚的降雨与亚速尔群岛亚热带高压系统的强度密切相关，这些洞穴遗址位于其气候中心。具体而言，该项目旨在利用葡萄牙中部和南部洞穴遗址的近2500年来的多代石笋记录（碳和氧稳定同位素比率、微量元素丰度、生长层和高精度铀/钍定年），弥合水文气候知识差距。通过测量、计算和比较一根石笋的最高铀钍年龄，这些层状物似乎是一年生的。由此产生的数据将与伊比利亚北部（西班牙）和非洲西北部（摩洛哥）类似分辨率的水文气候敏感记录相结合并进行评估，从而创建一个纬度样带，允许对亚速尔高原进行时空限制。这项研究还可以在该地区现有的唯一高分辨率古水文气候重建（摩洛哥北部和西班牙北部）之间提供重要的空间桥梁。总之，这些时间序列将使我们能够更全面地评估区域气候系统随时间的动态变化，特别是亚速尔高压的空间范围和强度。近千年来，特别是中世纪，北大西洋地区的大气环流状况，在代理研究和基于模式的研究中，仍然存在相当大的争议。特别令人感兴趣的是北大西洋涛动（NAO），这是冰岛低压和亚速尔群岛高压之间的大气偶极子，它通过风暴路径的路径与西欧和西北非洲的区域年际降水变化密切相关。在19世纪末之前，人们对NAO和亚速尔高原的动力学知之甚少，因此，NAO/亚速尔高原动力学的驱动因素没有得到充分的探索。解决这些缺陷的理想地点是葡萄牙中部和南部，那里几乎没有（如果有的话）高分辨率的记录。潜在的更广泛影响（bi）包括有可能改变对过去伊比利亚水文气候变率的性质和驱动因素的理解，并通过与模式模拟的比较，了解它如何对未来的人为强迫作出反应。因此，这些高分辨率和精确年代记录的开发和合成将对广泛的气候/古气候群落有价值。作为该项目的一部分而产生的所有数据将在社区网站上公开提供和存档。该项目联合了来自主要研究机构（爱荷华州立大学、伍兹霍尔海洋研究所、新墨西哥大学）和文理学院（康奈尔学院、联合学院）的多元化、国际公认的研究人员团队，采用多学科方法解决长期水文气候动力学问题。这项工作将包括培训一名已经在爱荷华州立大学居住的博士生和至少八名最先进的气候重建和建模技术的本科生研究人员。在葡萄牙，数据收集的一个组成部分将包括在当地的一个旅游洞穴进行以公民为基础的科学研究，并与地区洞穴探索小组合作。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 Mediterranean region is identified as a climate change hot spot. Recent observations, including increased fire activity in 2017, suggest that aridity in the Iberian Peninsula is already increasing. This multi-institutional team of researchers seeks to provide a spatial and temporal context for on-going and future climatic changes in this region by constructing a 2,500-year-long history of hydroclimate variability from precipitation-sensitive stalagmites formed in caves in central and southern Portugal. Rainfall in Iberia is strongly correlated to the strength of the Azores sub-tropical high-pressure system, and these cave sites lie at its climatological epicenter. Specifically, this project aims to bridge the hydroclimate knowledge gap for the last 2,500 years using sub-decadally resolved, multi-proxy stalagmite records (carbon and oxygen stable isotope ratios, trace element abundances, growth laminae, and high precision Uranium/Thorium dating) from cave sites in central and southern Portugal. Based on measuring, counting and comparing the uppermost Uranium/Thorium age from one stalagmite, these laminae appear to be annual in nature. Resulting data will be combined and evaluated with similarly-resolved hydroclimate-sensitive records from northern Iberia (Spain) and northwest Africa (Morocco), creating a latitudinal transect that will allow spatial and temporal constraints to be placed on the Azores HighThis research could also provide a significant spatial bridge between the only existing high-resolution paleo-hydroclimatic reconstructions (northern Morocco and northern Spain) from this zone. Together, these time series will allow for a more comprehensive evaluation of dynamical changes in the regional climate system through time, particularly in the spatial extent and intensity of the Azores High.The state of the atmospheric circulation in the North Atlantic region during recent millennia, and particularly medieval times, remains the subject of considerable debate in both proxy- and model-based studies. Of particular interest is the North Atlantic Oscillation (NAO), an atmospheric dipole between the Iceland low and the Azores high, which is strongly linked to regional inter-annual precipitation variability in Western Europe and northwest Africa through the routing of storms tracks. Dynamics of the NAO and the Azores High are poorly understood prior to the late 19th century, and as a result, the drivers of NAO/Azores High dynamics have not been adequately explored. An ideal place to address these deficiencies is central and southern Portugal, where few, if any, high-resolution records exist.The potential Broader Impacts (B.I.) includes the potential to transform the understanding of the nature and drivers of past Iberian hydroclimate variability, and through comparison with model simulations, how it may respond to future anthropogenic forcing. As such, the development and synthesis of these high resolution and precisely dated records will be of value to the broad climate/paleoclimate communities. All data produced as part of this project will be made publicly available and archived on community websites. The project unites a diverse, internationally recognized team of researchers from major research institutions (Iowa State University, Woods Hole Oceanographic Institution, University of New Mexico) and liberal arts colleges (Cornell College, Union College) to apply multi-disciplinary approaches to addressing long-term hydroclimate dynamics. This work will involve the training of a PhD student already in residence at Iowa State and at least eight undergraduate researchers in state-of-the-art climate reconstruction and modeling techniques. A component of data collection in Portugal will involve citizen-based science at a local tourist cave and with regional caving groups.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.