Accomplished Based Renewal: A Glacial Age Synthesis of Western North Atlantic Hydrography

已完成的基础更新：北大西洋西部水文学的冰川时代综合

• 批准号: 2224312
• 负责人: Lloyd Keigwin
• 金额: $ 17.78万
• 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: 2022
• 资助国家: 美国
• 起止时间: 2022-09-01 至 2025-08-31
• 项目状态: 未结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=2224312&HistoricalAwards=false
• 关键词: Accomplished; Based; Renewal; Glacial; Age

In the present day, warm and salty near surface waters of Gulf Stream origin are transported to high latitudes where they give up their heat and warm northeast Europe. At the same time the surface waters become denser and exit the Nordic (Greenland, Iceland, and Norwegian) Seas and over about 1000 years spread to other parts of the ocean. This process was interrupted during glacial times because the Nordic Seas were freshened by water from nearby ice sheets, and climate in Europe was more like Greenland today. As a result, it is often thought that deep ocean circulation was “off” during glaciation, and “on” during interglacial climate. Considering the size and climate impact of deep ocean circulation, the deep ocean is poorly sampled. For example, only recently it was found that at depths greater than 5000 m there was a dense, salty water that must have been produced in the Nordic or Labrador Seas during glacial times. So now it can be stated that the glacial circulation was probably never “off.” This project will increase the existing database of glacial-age sediment properties from the western subtropical North Atlantic by about 30 percent, and that in turn will lead to a first three-dimensional picture of the “state” of the glacial ocean where the export of heat, salt, nutrients, and carbon dioxide can be modeled and quantified.To accurately reconstruct past changes in deep water circulation requires a wide distribution of stable isotope (d18O and d13C) measurements and radiocarbon dates on microscopic fossil shells from deep sea sediment cores at various locations and depths. These cores were collected by the Principal Investigator on research cruises from 1994, 1998, 2004, 2010, 2017, 2019, and 2021 and new data will be developed for a dozen of them. The stable isotopes are proxies for deep ocean temperature, salinity and CO2 content, and radiocarbon data from plankton will be used to identify the last glacial maximum (about 20,000 years ago) as well as act as a tracer for the age of the deep water in shells of bottom dwelling microfossils. In addition, the glacial maximum data compilation will include cores from the upper 2 km of the western North Atlantic, where there are few data, but very strong gradients in paleo properties are indicative of salinity, temperature, nutrients, and transport in Glacial North Atlantic Intermediate Water. The synthesis data will be useful for studying the ocean’s capacity to store and transport heat, salt, and nutrients and will be used to validate climate models.This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.

在今天，温暖和咸的近地表沃茨的墨西哥湾流起源被输送到高纬度地区，在那里他们放弃了他们的热量和温暖的欧洲东北部。 与此同时，表面的沃茨变得更稠密，并离开北欧（格陵兰，冰岛和挪威）海，并在大约1000年的时间里扩散到海洋的其他部分。 这一过程在冰河时期被打断，因为北欧海洋被附近冰盖的水所刷新，欧洲的气候更像今天的格陵兰岛。 因此，人们通常认为，深海环流在冰期是“关闭”的，而在间冰期是“开启”的。 考虑到深海环流的规模和气候影响，对深海的取样很少。 例如，直到最近才发现，在深度超过5000米的地方有一种密集的咸水，这种咸水一定是在冰川时期在北欧或拉布拉多海产生的。 因此，现在可以说，冰川循环可能从来没有“关闭”。该项目将把现有的北大西洋西部亚热带冰川时代沉积物特性数据库增加约30%，这反过来又将导致第一个冰川海洋“状态”的三维图像，在那里输出热量，盐，营养物质，为了准确地重建过去深水循环的变化，需要广泛分布的稳定的对不同地点和深度的深海沉积物岩芯中的微观化石壳进行同位素（d18O和d13C）测量和放射性碳年代测定。 这些核心是由首席研究员在1994年，1998年，2004年，2010年，2017年，2019年和2021年的研究巡航中收集的，其中十几个将开发新的数据。 稳定同位素是深海温度、盐度和二氧化碳含量的代用指标，浮游生物的放射性碳数据将用于确定末次盛冰期（约2万年前），并作为底栖微化石外壳中深水年龄的示踪剂。 此外，最大冰期数据汇编将包括来自北大西洋西部上部2公里的岩心，那里的数据很少，但古属性的非常强的梯度表明北大西洋冰期中层水的盐度、温度、营养物质和运输。 综合数据将有助于研究海洋储存和运输热量、盐和营养物质的能力，并将用于验证气候模型。该奖项反映了NSF的法定使命，并被认为值得通过使用基金会的知识价值和更广泛的影响审查标准进行评估来支持。