OCE-RIG: Variability in Atlantic Meridional Overturning Circulation (AMOC) strength and hydrological conditions in the central Sahara/Sahel during the Pliocene-Pleistocene

在该项目中，首席研究员将使用多代理地球化学方法研究萨赫勒地区过去AMOC的变化和水文学，已知大西洋纬向翻转环流（AMOC）强度的变化对北大西洋周围地区（包括欧洲、北美和西北非洲）的全球气候有重大影响。根据政府间气候变化专门委员会目前的模型模拟，预测AMOC可能在世纪减缓。因此，重要的是要更好地了解过去的AMOC变化及其对海洋和大陆气候的影响，以及进一步开发和完善过去AMOC变化的指纹识别方法。热带北大西洋AMOC减缓的一个显著特征是表面冷却伴随着浅次表面（30米）变暖。最近对热带北大西洋的一项研究表明，有机地球化学温度代用指标可用于同时重建地表和地下水温。通过这项研究工作，将利用多代用地球化学方法来检查ODP孔660 A的沉积物，从而重建萨赫勒地区的AMOC变化和水文条件。该项目的目的是测试的假设，在热带北大西洋的表面和次表层水温之间的反相关变化的特征AMOC签名也存在较长的几千年到百万年的时间尺度。这项研究将提供新的记录，海洋表面温度（SST），次表层温度，以及大陆植被和水文在上新世-更新世，这将被用来检查AMOC和大陆水文之间的关系。一个特别的重点是上新世中期的温暖时期，地球上的未来变暖的模拟，并在上新世晚期的北方半球冰川的开始和加强，当哺乳动物和人类进化的重大步骤发生。一个新的上新世更新世SST记录，这项工作将被用来检查的纬向和纬向SST梯度的演变。教育是该项目更广泛影响的重要组成部分。这项建议的教育方面包括培训一名研究生、两名本科生和六名高中科学教师。拟议的活动将向高中生介绍海洋科学这一令人兴奋的学科，并向他们提供关于这一领域就业机会的信息。为了提高代表性不足的群体对海洋科学的认识，以及提高对海洋科学的全面参与，将从没有地球科学课程的高中招聘科学教师。高中教师将在夏季访问马萨诸塞州阿默斯特大学，并与PI和研究生合作，制作可以纳入高中化学，生物和物理课程的课堂活动。随后，PI，本科生和研究生将在学年期间访问每位教师的家乡高中，向学生介绍海洋科学的就业机会。该项目得到了NSF海洋科学研究启动资助（OCE-RIG）计划的支持，其目标是支持早期职业科学家的新研究，并增加美国海洋科学劳动力和研究社区的多样性。在海洋环境研究所的支持下，该项目将使有前途的早期职业研究人员能够在与海洋科学有关的独立研究生涯中立足，并扩大代表性不足的群体对海洋科学的参与。

In this project, the principal investigator will examine past AMOC variability and hydrology in the Sahel using a multi-proxy geochemical approach.Changes in the strength of the Atlantic meridional overturning circulation (AMOC) are known to have a major influence on global climate with the areas around the North Atlantic, including Europe, North America, and northwest Africa. It is predicted that the AMOC may slow down during the 21st century, based on current model simulations from the Intergovernmental Panel on Climate Change. Therefore, it is important to develop a better understanding of past AMOC variability and its impacts on ocean and continental climates as well as to further develop and refine methods for fingerprinting past AMOC variability. A distinctive feature of AMOC slowdown in the tropical North Atlantic is surface cooling accompanied by shallow subsurface (30 m) warming. A recent study of the tropical N Atlantic demonstrated that organic geochemical temperature proxies can be used to simultaneously reconstruct surface and subsurface water temperatures. Through this research effort, the AMOC variability and hydrological conditions in the Sahel will be reconstructed by using a multi-proxy geochemical approach to examine sediments from ODP Hole 660A. This project is designed to test the hypothesis that the characteristic AMOC signature of anti-correlated variation between surface and subsurface water temperatures in the tropical N Atlantic also existed on longer multi-millennial to million-year timescales. This research will provide new records of sea surface temperature (SST), subsurface temperature, and continental vegetation and hydrology during the Pliocene-Pleistocene, which will be used to examine relationships between AMOC and continental hydrology. A particular focus is on the mid-Pliocene warm period, an analog for future warming on Earth, and during the onset and intensification of Northern Hemisphere glaciations in the late Pliocene, when major steps in mammalian and hominin evolution occurred. A new Plio-Pleistocene SST record generated by this work will be used to examine the evolution of zonal and latitudinal SST gradients. Education is an important part of the broader impacts of this project. The educational aspects of this proposal consist of training a graduate student, two undergraduates, and six high school science teachers. The proposed activities will introduce high school students to the exciting subject of ocean sciences and provide them with information on career opportunities in this field. In an effort to increase awareness of the ocean sciences to under-represented groups, as well as overall participation in the ocean sciences, science teachers will be recruited from high schools lacking Earth Sciences curriculum. The high school teachers will visit the University of Massachusetts-Amherst during the summer and work with the PI and graduate student to produce classroom activities that can be incorporated into high school chemistry, biology and physics courses. Subsequently, the PI, undergraduates and graduate student will visit the home high school of each teacher during the academic year to inform students about career opportunities in the ocean sciences. This project is supported under the NSF Ocean Sciences Research Initiation Grant (OCE-RIG) program, with goals to support novel research by early career scientists and increase the diversity of the U.S. ocean sciences workforce and research community. With OCE-RIG support, this project will enable a promising early career researcher to establish themselves in an independent research career related to ocean sciences and broaden participation of under-represented groups in the ocean sciences.