Collaborative Research: Testing the Northern Route for Younger Dryas Meltwater

合作研究：测试新仙女木融水的北方路线

• 批准号: 1204045
• 负责人: Lloyd Keigwin
• 金额: $ 77.81万
• 依托单位: Woods Hole Oceanographic Institution
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 2012
• 资助国家: 美国
• 起止时间: 2012-07-01 至 2018-06-30
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=1204045&HistoricalAwards=false
• 关键词: Collaborative; Research; Testing; Northern; Route

The PIs propose a three-year project to investigate the origin of the Younger Dryas cooling. New evidence suggests that glacial Lake Agassiz released fresh water to the Arctic through the Mackenzie River and they propose that this signal should be detectable along the western margin of the Canadian Archipelago in the oxygen isotope ratio in the shells of planktonic foraminifera. The project involves a three-week expedition to survey the seafloor and subbottom layers and collect sediment cores from the eastern Beaufort Sea, a region that is remote and has not been well explored. Besides the sediment processing and micropaleontology that are part of generating the isotope data that reflect sea surface salinity, two complementary shore-based projects are proposed. The first is to integrate the new geophysical data on the continental margin with the climate history of the open sea, sediment transport, relative sea level change, and terrestrial climate, as they have done previously for the Chukchi Sea. The second is to compare the geochemical data with results from a high resolution General Circulation Model that is configured to reveal the path and the mixing of the melt water. Although the paleoceanographic data will be spatially limited, model runs will show the low salinity distribution in the Arctic as well as in the Nordic seas where the freshening may have affected deep ocean overturning and caused the Younger Dryas cooling.The Younger Dryas was a period of climatic cooling that began about 13,000 years ago and lasted more than 1000 year. It reversed a period of climatic warming, even though insolation continued to increase. This study will attempt to determine the mechanism that allowed such a reversal in temperature trend to occur and, thus, inform discussions of whether similar changes are probable in the future.

PIs提出了一个为期三年的项目来调查新仙女木期降温的起源。新的证据表明，冰川湖阿加西斯通过麦肯齐河向北极释放淡水，他们提出，这个信号应该可以在加拿大群岛西部边缘的浮游有孔虫壳的氧同位素比率中检测到。该项目包括一个为期三周的考察，调查海底和海底下层，并收集波弗特海东部的沉积物岩心，这是一个偏远且尚未得到充分勘探的地区。除了沉积物处理和微古生物学是生成反映海面盐度的同位素数据的一部分外，还提出了两个互补的岸基项目。第一个是将大陆边缘的新地球物理数据与公海的气候历史、沉积物运输、相对海平面变化和陆地气候相结合，就像他们之前对楚科奇海所做的那样。第二步是将地球化学数据与高分辨率环流模型的结果进行比较，该模型被配置为揭示熔融水的路径和混合。尽管古海洋学数据在空间上是有限的，但模式运行将显示北极和北欧海的低盐度分布，在北欧海，海水变新鲜可能影响了深海的翻覆，并导致了新仙女木期的冷却。新仙女木期是一个气候变冷的时期，始于大约13000年前，持续了1000多年。它扭转了一段时期的气候变暖，尽管日晒量继续增加。这项研究将试图确定使这种温度趋势发生逆转的机制，从而为将来是否可能发生类似变化的讨论提供信息。