Rekonstruktion der Atlantischen Zirkulation innerhalb des letzten Glazialen Zyklus
Rekonstruktion der Atlantischen Zirkulation innerhalb des letzten Glazialen Zyklus
复制标题
末次冰期期间大西洋环流的重建
DOI：
10.11588/heidok.00016524
复制
发表时间：
2014
期刊：
影响因子：
--
通讯作者：
中科院分区：
文献类型：
--
作者：
过去150 kyr的气候主要是由轨道强迫导致的长期冰川条件框架的短期温暖期Eemian和全新世。为了了解这种气候变率，至关重要的是调查大西洋经向翻转环流（AMOC）对日射的响应，以及它通过重新分配热量和CO2对气候的影响。然而，在调查的时间段内，确定AMOC变化的机制知之甚少。在这项研究中，AMOC的强度和方向检查的时间高分辨率测量的两个代理231 Pa/230 Th和eNd从海洋沉积物芯ODP 1063，这是位于西北大西洋。尽管231 Pa的半衰期很短，但直到134 kyr才获得了显着的231 Pa/230 Th比率，这将迄今为止发布的范围扩大了9 kyr。在Dansgaard-Oeschger暖事件期间，发现了北方深水形成和环流动力学的变化，并识别出罕见的早冰期Heinrich冷事件（H7、H9和H10）。它表明，终端II缺乏一个新仙女木一样的冷事件，由于夏季日照的差异。与人们普遍认为的在完全冰期条件下AMOC一般较浅和较弱的观点相反，在MIS 4和MIS 3早期，发现了与大西洋深层北方水源水有关的环流强度减弱。由于这种环流模式与迄今所描述的环流模式有显著差异，因此定义了新的“中间模式”。
The climate of the last 150 kyr is mainly driven by orbital forcing leading to long-lasting glacial conditions framed by the short warm periods Eemian and Holocene. To understand this climate variability it is crucial to investigate the response of the Atlantic Meridional Overturning Circulation (AMOC) on the insolation and the consequent effect it has on the climate by redistributing heat and CO2. However, the mechanisms that determine changes of the AMOC are poorly understood within the investigated time period. In this study the strength and direction of the AMOC is examined by temporal high-resolution measurements of the two proxies 231Pa/230Th and eNd from the marine sediment core ODP 1063 which is situated in the North West Atlantic. Despite the short half life of 231Pa, significant 231Pa/230Th ratios were obtained until 134 kyr which extends the so far released scope by 9 kyr. During Dansgaard-Oeschger warm events variations in the northern deep water formation and circulation dynamics are found. Further, rarely detected Heinrich cold events from the early glacial (H7, H9 and H10) are identified. It is demonstrated that the Termination II lacks a Younger Dryas-like cold event due to differences in the summer insolation. Instead to the widely perceped view of a generally shallow and weak AMOC during full glacial conditions, a reduced circulation strength associated with northern sourced water in the deep Atlantic during MIS 4 and the early MIS 3 are found. Due to the significant difference of this pattern to the so far described circulation modes, the new `intermediate mode' is defined.