Biogeochemical linkages between Ice Age climate, ocean productivity, and carbon cycling

该研究计划的目标是通过从沉积记录中存档的古环境指标重建过去的海洋条件，探索海洋环流，海洋生产力和碳（C）循环之间的联系。三个互补的项目，将遵循相同的方法：新的生物通量，海表温度和模式水代用数据将产生从东南（SE）太平洋的深海核心，选择他们的战略重要性的研究问题和他们的能力，以填补目前的知识空白。这些新数据将纳入正在进行的全球生物通量数据综合，其中包括关于碳积累和海洋浮游植物丰度变化的七个指标的信息，以重建海洋生产力不同组成部分变化的相对时间。最后，这些数据将被用来评估精心设计的模型的敏感性实验中，海冰覆盖，铁施肥，上升流强度的变化，和淡水强迫已实施。模拟的生产力变化将与观测到的冰河时代重建进行比较，以评估哪些过程提供了最佳匹配的数据，为以下项目：项目1探讨海冰覆盖和灰尘对二氧化硅和碳循环的影响。 项目2研究了南半球环流变化的影响（例如，西风、海洋锋、亚季风型水的形成）对生产力的影响。 项目3调查从最后一个冰河时代到今天的过渡期间极地表面清新和相关环流变化对海洋生产力的潜在影响。 拟议的研究将提供新的重建过去的海洋条件在东南太平洋在最后一个冰河时代。 全球古环境数据集为分析海洋地球化学模型模拟提供了广泛而新颖的评估工具，有利于地球系统科学领域。这些结果将有助于我们目前对冰河时代海洋碳循环的了解，确定负责大气二氧化碳冰河时代变化的海洋机制。

The goal of this research program is to explore the linkages between ocean circulation, marine productivity, and carbon (C) cycling by reconstructing past ocean conditions from paleo-environmental indicators archived in the sedimentary record. Three complementary projects are proposed that will follow the same approach: New biogenic flux, sea-surface temperature, and mode-water proxy data will be generated on deep-sea cores from the southeast (SE) Pacific Ocean, selected for their strategic importance to the research questions and their ability to fill a gap in current knowledge. These new data will be placed within the context of an ongoing global biogenic flux data synthesis that incorporates information on seven indicators of changes in C accumulation and marine phytoplankton abundance, to reconstruct the relative timing of changes in different components of marine productivity. Finally, these data will be used to evaluate carefully designed model sensitivity experiments in which changes in sea-ice cover, iron fertilization, upwelling intensity, and freshwater forcing have been imposed. Simulated changes in productivity will be compared with observed ice age reconstructions to assess which processes provide the best match to the data for the following projects: PROJECT 1 explores the influence of sea-ice cover and dust on silica and C cycling. PROJECT 2 examines the influence of changed Southern Hemisphere circulation (e.g., westerly winds, oceanic fronts, Subantarctic Mode Water formation) on productivity. PROJECT 3 investigates the potential influence of polar surface freshening and associated circulation changes on marine productivity during the transition from the last Ice Age to today. The proposed research will provide new reconstructions of past oceanic conditions in the SE Pacific Ocean during the last Ice Age. The global paleo-environmental datasets benefit the field of Earth System science by providing extensive and highly novel evaluation tools for analyzing ocean biogeochemistry model simulations. The results will contribute to our current knowledge of the ice age ocean C cycle, identifying oceanic mechanisms responsible for ice-age changes in atmospheric carbon dioxide.