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

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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.