A Combined Paleo-Proxy and Modeling Study of Abrupt Climate Change in the Tropical Atlantic and Its Relation to Atlantic Meridional Overturning Circulation Variability

耦合气候模式模拟和仪器数据分析都表明，大西洋大尺度环流（也称为大西洋纬向翻转环流，或AMOC）的变化可能通过大气和海洋过程与热带北大西洋和次表层温度变化紧密耦合。虽然AMOC的减缓导致整个热带北大西洋的大气引起的表面冷却，但由于海洋环流模式的快速重组，次表层经历了更大的变暖。因此，最近的模拟研究和观测数据指出，热带北大西洋西部的地下是对AMOC变化最敏感的热带大西洋区域。这项研究由德克萨斯州A M大学的古海洋学家和气候模拟师共同领导&，将海面和次表层温度和盐度的代用重建与气候模式模拟相结合，以识别和理解海洋环流、高纬度变率和热带大西洋气候。具体而言，研究人员将使用时间切片方法来研究热带北大西洋西部垂直温度和盐度变化的演变，这些变化与最后一次冰川消退中三个最重要的事件（Heinrich事件1，Bolling-Allerod和Younger Dryas）的大气和海洋环流变化直接相关。他们还将通过生成过去6万年的类似代理记录来测试模型结果的保真度。总的来说，他们试图检验这样一个假设，即北大西洋高纬度地区的寒冷时期对应于热带北大西洋西部地区的强烈次表层变暖，这表明热带北大西洋西部地区的次表层温度变化是AMOC变化的敏感指标。这项研究将提高对海洋环流和气候变化之间相互作用的理解，并有可能提高对热带大西洋气候变化的预测能力。资金支持两名研究生，并促进两个研究社区之间的更大合作。

Both coupled climate model simulations and instrumental data analyses indicate that variability in the large scale circulation of the Atlantic Ocean (also called the Atlantic meridional overturning circulation, or AMOC) may be tightly coupled to tropical North Atlantic and subsurface temperature variability through both atmospheric and oceanic processes. While a slowdown of the AMOC results in an atmospheric-induced surface cooling in the entire tropical North Atlantic, the subsurface experiences an even larger warming due to rapid reorganizations of ocean circulation patterns. As a result, recent modeling studies and observational data point to the subsurface of the western tropical North Atlantic as the most sensitive Tropical Atlantic region to respond to AMOC variability.This study, co-led by a paleoceanographer and a climate modeler from Texas A & M University, combines proxy reconstructions of sea surface and subsurface temperature and salinity with climate model simulations to identify and understand teleconnections between ocean circulation, high latitude variability, and tropical Atlantic climate. Specifically, the researchers will use a time slice approach to investigate the evolution of vertical temperature and salinity change in the western Tropical North Atlantic linked directly to atmospheric and ocean circulation changes during three of the most significant events of the last deglaciation (Heinrich Event 1, the Bolling-Allerod, and the Younger Dryas). They will also test the fidelity of model results by generating similar proxy records for the past 60,000 years. Overall they seek to test the hypothesis that cold periods on the high-latitude North Atlantic correspond to intense subsurface warming in the western tropical North Atlantic, suggesting that western tropical North Atlantic subsurface temperature change is a sensitive indicator of AMOC variability. This research will improve understanding of the interplay between ocean circulation and climate change, and could potentially improve predictive capability of tropical Atlantic climate variability. Funding supports two graduate students and fosters greater collaboration between two communities of researchers.