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资料分析均表明，大西洋大尺度环流（也称为大西洋经向翻转环流或AMOC）的变率可能通过大气和海洋过程与热带北大西洋和地下温度变率紧密耦合。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，地下经历了更大的变暖。因此，最近的模拟研究和观测数据表明，西热带北大西洋的地下是对AMOC变率响应最敏感的热带大西洋区域。这项研究由来自德克萨斯农工大学的古海洋学家和气候建模师共同领导，将海面和地下温度和盐度的代理重建与气候模型模拟相结合，以确定和理解海洋环流、高纬度变化和热带大西洋气候之间的远相关关系。具体来说，研究人员将使用时间切片方法来研究在最后一次冰川消退的三个最重要的事件（海因里希事件1、博林-阿勒罗德事件和新仙女木事件）中，与大气和海洋环流变化直接相关的西热带北大西洋垂直温度和盐度变化的演变。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，他们试图验证高纬度北大西洋的寒冷时期与北大西洋西部热带地区强烈的地下变暖相对应的假设，这表明北大西洋西部热带地区的地下温度变化是AMOC变率的一个敏感指标。这项研究将提高对海洋环流与气候变化之间相互作用的认识，并有可能提高对热带大西洋气候变率的预测能力。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.