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

学术价值：本研究旨在通过利用浮游生物和底栖有孔虫钙化试验的地球化学，根据北大西洋经向翻转环流（AMOC）的变率重建热带/亚热带大气环流变化的时间，从而确定末次冰期最大气候事件的原因。最近的研究结果表明，北大西洋末次冰期的盐度变化表明，气候突变事件与低纬度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起着重要作用。研究将包括记录过去的海面温度和盐度以及大规模的海洋环流变化，方法是在佛罗里达海峡沉积物岩心的有孔虫测试中使用独特的温度和盐度代用物。代用物包括Mg/Ca古测温、氧同位素分析和浮游有孔虫测试中的Ba/Ca比值。来自同一岩心的底栖（海底栖息）有孔虫记录的配套数据将确定佛罗里达洋流在主要气候转变中的运输变化时间。由于信号之间的相对时间将在单个核心中建立，因此研究目标将是确定对亚热带/热带大西洋水文循环对水文循环的影响，并检查末次冰期由大气环流变化驱动的突变气候事件，然后影响AMOC。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我们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气候突变期间热带水文循环的变化。此外，伴随的中水密度变化的高分辨率记录有可能确定过去4万年中最大气候转变期间大规模海洋环流变化的速率和时间，并可用于气候模型，以预测近期水文循环的变化将如何改变不久的将来的全球气候。数据将被保存在位于科罗拉多州博尔德的美国国家海洋和大气管理局的世界古气候学数据中心。结果将被纳入德州农工大学的研究生课程。这项工作将支持一名研究生，并包括对本科生的培训。将努力通过德州农工大学(Texas A&amp；M？美国多元文化服务部。

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.