Application of Transient Time Distributions to Ocean Radiocarbon Records for the Last Deglaciation

放射性碳(14C)是海洋环流的重要示踪剂。然而，尽管已经开发了大量的海洋Delta14C记录，但缺乏对这些记录的定量解释。这项拟议中的工作由伍兹霍尔海洋研究所的研究人员领导，将采用一种新颖的、定量的方法来记录上次冰川消融后的深层和表层水域的Delta14C记录。该项目将生成Delta14C记录的最新汇编以及相关的不确定性估计。渡越时间分布(TTD)计算将应用于这些记录，以将深水Delta14C浓度与地表水中的浓度联系起来。具体地说，从现代水文数据得出的TTD将用于计算地表水记录所暗示的深水Delta14C的变化，反之亦然。这种方法将检验这样一种假设，即在上次冰川消融期间，深海和地表水Delta14C值的急剧下降是由海洋通风的变化共同推动的。该项目将联合海洋模型师、物理海洋学家和古海洋学家的专业知识，解决冰川消融条件下海洋循环的一个关键问题。一名研究生将参与这项研究，并将为本科生提供暑期支持。项目数据、计算软件和随附的“如何操作”文档将在NOAA的国家气候数据中心存档。

Radiocarbon (14C) is an important tracer of ocean circulation. However, although extensive marine Delta14C records have been developed, quantitative interpretations of these records are lacking. The proposed work, led by researchers at Woods Hole Oceanographic Institution, will take a novel, quantitative approach to Delta14C records of deep and surface waters from the last deglaciation. The project will generate an up-to-date compilation of Delta14C records with associated uncertainty estimates. Transit time distribution (TTD) calculations will be applied to these records to relate deepwater Delta14C concentrations to those in surface waters. Specifically, TTDs derived from modern hydrographic data will be used to compute the changes in deepwater Delta14C that are implied by the surface water records, and vice versa. This approach will test the hypothesis that steep declines in deep and surface water Delta14C values during the last deglaciation were jointly driven by a change in ocean ventilation. This project will unite the expertise of an ocean modeler, a physical oceanographer, and a paleoceanographer to address a key question about ocean circulation during conditions of deglaciation. A graduate student will be involved in the research, and summer support for an undergraduate student will be provided. Project data, computational software, and accompanying "how-to" documentation will be archived at NOAA's National Climatic Data Center.