Atlantic Ocean circulation changes preceded millennial tropical South America rainfall events during the last glacial
Atlantic Ocean circulation changes preceded millennial tropical South America rainfall events during the last glacial
复制标题
DOI：
10.1002/2014gl062512
复制
发表时间：
2015-01-28
影响因子：
5.2
通讯作者：
Thil, Francois
中科院分区：
文献类型：
--
作者：
Burckel, Pierre;Waelbroeck, Claire;Thil, Francois
在末次冰期期间，格陵兰的气候在寒冷（冰阶）和温暖（间冰阶）阶段之间转换，同时伴随着海洋环流的变化，其特征是在冰阶期间大西洋经向翻转环流（AMOC）减弱。在此，我们展示了来自热带大西洋西部的新数据，这些数据表明AMOC的减缓先于冰阶期间发生的一些南美洲大型降雨事件。基于同一沉积岩芯中的镤 - 231/钍 - 230和钛/钙测量值，我们确定在与海因里希冰阶相关的两次大型降水事件开始之前，AMOC分别在1420 ± 250年和690 ± 180年（1标准差）开始减缓。我们的研究结果提供了前所未有的证据，表明AMOC的变化可能是海因里希冰阶期间在热带南美洲观测到的大型降水事件的根源。此外，我们提出了一种机制，用于解释与较短和较长冰阶相关的AMOC减缓程度和时间的差异。
During the last glacial period, Greenland's climate shifted between cold (stadial) and warm (interstadial) phases that were accompanied by ocean circulation changes characterized by reduced Atlantic Meridional Overturning Circulation (AMOC) during stadials. Here we present new data from the western tropical Atlantic demonstrating that AMOC slowdowns preceded some of the large South American rainfall events that took place during stadials. Based on Pa-231/Th-230 and Ti/Ca measurements in the same sediment core, we determine that the AMOC started to slowdown 1420250 and 690180 (1 sigma) years before the onset of two large precipitation events associated with Heinrich stadials. Our results bring unprecedented evidence that AMOC changes could be at the origin of the large precipitation events observed in tropical South America during Heinrich stadials. In addition, we propose a mechanism explaining the differences in the extent and timing of AMOC slowdowns associated with shorter and longer stadials.