Linking Atmospheric and Ocean Circulation Variability to Abrupt Climate Change Over the Last 40 Kyr

知识价值：这项研究试图通过利用浮游和底栖有孔虫钙化测试的地球化学来重建热带/副热带大气环流变化与北大西洋经向翻转环流AOC变化有关的时间，以确定上一次冰川周期最大气候事件的原因。这项工作的动机是最近的研究结果，即上一次冰川周期期间北大西洋盐度的变化表明，气候突然变化事件与低纬水文循环的显著变化有关，这表明热带大气环流在气候变化中发挥着重要作用。研究将包括记录过去的海表面温度和盐度以及通过使用来自佛罗里达海峡沉积物岩心的有孔虫测试中独特的温度和盐度替代指标来记录大规模海洋环流变化。代用指标包括镁/钙古测温法、氧同位素分析和浮游(漂浮)有孔虫测试中的巴/钙比值。来自相同岩心的海底(海底)有孔虫记录的配套数据将确定佛罗里达州目前在主要气候过渡期间的交通变化的时间。由于信号之间的相对时序将在一个核心内确定，研究目标将是确定对副热带/热带大西洋水文循环的影响，并检查上一次冰川时期的突然气候事件，这些事件是由大气环流变化驱动的，然后影响大气层环流。更广泛的影响：最近大气中温室气体的增加及其加强水文循环的潜力使迫切需要更好地了解淡水通量在海洋-大气相互作用中的作用。这项研究将有助于我们了解热带水文循环在突发性气候事件中的过去变化。此外，伴随的中水密度变化的高分辨率记录有可能确定在过去40 000年来最大的气候过渡期间大规模海洋环流变化的速度和时间，并可用于气候模型，以预测最近水文循环的变化将如何在不久的将来改变全球气候。数据将在科罗拉多州博尔德市NOAA的世界古气候学数据中心存档。结果将被纳入德克萨斯农工大学的研究生班。这项工作将支持一名研究生，并包括对本科生的培训。将努力通过德克萨斯农工大学S多元文化服务部，从理科代表性不足的群体中招收本科生。

Intellectual Merit: This research seeks to identify the cause of the largest climate events of the last glacial cycle by using the geochemistry of the calcarious tests of planktonic and benthic foraminifera to reconstruct the timing of tropical/subtropical atmospheric circulation change in relation to variability in North Atlantic Meridional Overturning Circulation AMOC. The work is motivated by recent findings that North Atlantic Ocean salinity changes during the last glacial cycle show that abrupt climate change events are associated with significant changes in the low-latitude hydrologic cycle, suggesting that tropical atmospheric circulation plays an important role in climate change. Research will involve documenting past sea surface temperature and salinity as well as large-scale ocean circulation changes by using unique temperature and salinity proxies in foraminifera tests from sediment cores from the Florida Straits. Proxies include Mg/Ca-paleothermometry, oxygen isotope analyses, and Ba/Ca ratios in planktonic (floating) foraminifera tests. Companion data from benthic (seafloor dwelling) foraminiferal records from the same cores will identify the timing of Florida Current transport changes across major climate transitions. Because the relative timing between signals will be established in a single core, research goals will be to identify the influence on the subtropical/tropical Atlantic hydrologic cycle on the hydrologic cycle and to examine of abrupt climate events during the last glacial period were driven by atmospheric circulation change that then impacted AMOC. Broader Impacts: The recent rise in greenhouse gases in the atmosphere and their potential to strengthen the hydrologic cycle gives urgent need to better understanding the role of freshwater fluxes in ocean-atmosphere interactions. This research will help us understand past changes in the tropical hydrologic cycle during abrupt climate events. Furthermore, the companion high-resolution records of intermediate-water density changes have the potential to determine the rate and timing of large-scale ocean circulation change across the largest climate transitions of the last 40,000 years and can be used in climate modeles to predict how recent changes in the hydrologic cycle will alter global climate in the near future. Data will be archived at the World Data Center for Paleoclimatology at NOAA in Boulder, Colorado. Results will be incorporated into graduate classes at Texas A&M. The work will support a graduate student and include the training of undergraduates. Efforts will be made to recruit undergraduates from groups under-represented in the science through Texas A&M?s Department of Multicultural Services.