Collaborative Research: Carbon Isotope and geotracer-enabled simulation of the Transient Climate Evolution of the Deglacial Ocean (C-iTRACE-O)

合作研究：碳同位素和地理示踪剂支持的冰下海洋瞬态气候演化模拟（C-iTRACE-O）

• 批准号: 1600080
• 负责人: Zhengyu Liu
• 金额: $ 25.8万
• 依托单位: University of Wisconsin-Madison
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 2016
• 资助国家: 美国
• 起止时间: 2016-07-01 至 2018-01-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=1600080&HistoricalAwards=false
• 关键词: Collaborative; Research; Carbon; Isotope; geotracer

Global climate has undergone large changes during the last deglaciation (21,000 to 11,000 years ago), with a warming of ~3.5°C globally, a sea level rise of ~80 m, and the disappearance of the large continental ice sheets. The large magnitude of the signals and the availability of extensive paleoclimate data make this period an excellent target for investigating the mechanisms underlying climate change and for the validation of state-of-the-art Earth System Models (ESMs). However, up until now model simulations could not be directly compared with the paleoclimate records, as the models did not simulate the geochemical tracers ("proxies") on which the reconstructions are based. To address this issue and provide insights into several long-standing scientific questions about the evolution of the ocean's overturning circulation during the deglaciation, this project will perform the first transient ocean simulation of the deglaciation with the newly developed isotope modules in the ocean model of the Community Earth System Model (CESM1), allowing for direct model-data comparison of multiple marine paleo proxies. This project will contribute to STEM workforce development by supporting the training of two graduate students in climate modeling and model-data comparisons and by providing project leadership experience for an early career female scientist, who will work in close collaboration with U.S. and international colleagues. Results from this project will be used in undergraduate and graduate classes at the University of Colorado at Boulder and the University of Wisconsin-Madison and will be incorporated into public outreach through a project website and through general-audience talks. The output of the simulation (called C-iTRACE-O) will be made freely available though the Earth System Grid gateway, allowing the entire paleoclimate community to use it for their research. The simulation will also be contributed to the Paleoclimate Model Intercomparison Project transient deglacial working group, allowing for an evaluation of the CESM C-iTRACE compared to the deglacial simulations from other ESMs.By directly simulating oceanic carbon-isotopes (d13C and D14C), Neodymium (eNd), and Protactinium/Thorium (231Pa/230Th) for the deglaciation and by carrying out sensitivity experiments to investigate the physical mechanisms causing the changing isotopic and geotracer distributions in the transient simulation, it will be possible to address some long-standing scientific questions through direct comparisons to observations and by evaluating tracer-circulation relationships in the model itself, such as:- What was the source and routing of the low-radiocarbon CO2 released during the Mystery Interval? - What is the implication of the d13C evolution in the Atlantic for the deep ocean circulation during the last deglaciation and how much of the d13C change was caused by nutrient- and air-sea gas exchange effects versus circulation changes? - Why is the deglacial evolution of Antarctic Intermediate Water controversial among proxies, notably in eNd and carbon isotopes? - How does 231Pa/ 230Th represent the deglacial evolution of North Atlantic deep circulation and Southern Ocean upwelling?

在上次冰消期（21,000至11,000年前）期间，全球气候发生了巨大变化，全球变暖约3.5°C，海平面上升约80 m，大型大陆冰盖消失幅度很大。然而，信号和古气候数据的可用性使这一时期成为研究气候变化机制和验证最先进的地球系统模型（ESM）的绝佳目标。到目前为止，模型模拟无法直接与古气候记录进行比较，因为模型没有模拟重建所依据的地球化学示踪剂（“代理”）。为了解决这个问题并为几个长期存在的科学问题提供见解。为了了解冰消期期间海洋翻转环流的演变，该项目将利用社区地球系统模型（CESM1）海洋模型中新开发的同位素模块对冰消期进行首次瞬态海洋模拟，允许该项目将支持对两名研究生进行气候建模和模型数据比较方面的培训，并为一名早期职业女性科学家提供项目领导经验，从而促进 STEM 劳动力的发展。与美国和国际同事密切合作，该项目的结果将用于科罗拉多大学博尔德分校和威斯康星大学麦迪逊分校的本科生和研究生课程，并将通过项目网站和一般性纳入公共宣传活动。 -观众发言。模拟的输出（称为 C-iTRACE-O）将通过地球系统网格网关免费提供，允许整个古气候社区将其用于他们的研究。该模拟还将为古气候模型瞬态比较项目做出贡献。冰消工作组，允许对 CESM C-iTRACE 与其他 ESM 的冰消模拟进行比较。通过直接模拟海洋碳同位素（d13C 和D14C）、钕（eNd）和镤/钍（231Pa/230Th）用于消冰作用，并通过进行敏感性实验来研究瞬态模拟中引起同位素和地质示踪剂分布变化的物理机制，将有可能解决一些问题通过直接与观察结果进行比较以及评估模型本身中的示踪剂与循环关系，解决长期存在的科学问题，例如：-神秘间隔期间释放的低放射性碳 CO2 - 大西洋 d13C 演化对上次冰消期期间的深海环流有何影响？ d13C 变化有多少是由营养物和空气-海洋气体交换效应引起的环流变化？ - 为什么南极中层水的冰消演化在代理之间存在争议，特别是在 eNd 和碳同位素方面 - 231Pa/ 230Th代表北大西洋深层环流和南大洋上升流的冰消演化？