COLLABORATIVE RESEARCH: Modeling Permain Ocean Stagnation and Anoxia

805139 Kump重大生物和气候变化的间隔，如发生在新元古代、晚奥陶世、晚二叠世和白垩纪/第三纪界线，通常与海洋化学和同位素组成的显著偏移有关。 对这些事件的一些解释主要是基于直觉推理，认为温盐环流的速率急剧下降，即“海洋停滞”。“很少有物理海洋学的限制，如热，盐和动量平衡被带到承担这些问题。 因此，我们请求提供资金，进行一套动态海洋环流/海洋地球化学模型模拟，以定量评估这些“海洋停滞”假设的效力。 虽然我们的工作重点是晚二叠世事件，结果将广泛适用于地球历史的其他时间间隔，以及GFDL模块海洋模式将用于研究晚二叠世海洋的三维大气环流，通过与我们的同事在威斯康星州和芝加哥大学的合作提供大气边界条件。 这些边界条件预计将产生积极和缓慢的温盐环流状态。 少量的地球化学成分将被添加到这个模型中，使我们能够评估缺氧的空间分布。 三维模式产生的环流场将进行纬向平均，并用于二维多组分地球化学模式，以研究滞流的地球化学后果。 除了磷酸盐和氧之外，二维模型还将计算溶解的无机碳、硫和锶同位素组成的分布。 因此，我们将能够调查的假设，即一个活跃的海洋，释放有毒量的二氧化碳到大气中，并比较预测和观察到的同位素记录这样的事件。 将进行一些敏感性分析，包括模型对河流和热液输入变化、各种动力学和同位素参数以及泛大陆漂移离开南极的反应。

805139KumpIntervals of significant biotic and climatic change, such as those occurring in the Neoproterozoic, the late Ordovician, the latest Permian, and the Cretaceous/Tertiary boundary, are commonly associated with marked excursions in the chemical and isotopic composition of the ocean. Some explanations of these events have been based largely on intuitive reasoning that invokes dramatic decreases in the rate of thermohaline circulation, i.e. "ocean stagnation." Rarely have physical oceanographic constraints, such as heat, salt and momentum balance been brought to bear on such problems. We therefore request funding to conduct a suite of dynamic ocean circulation/biogeochemical model simulations to quantitatively assess the efficacy of these "ocean stagnation" hypotheses. Although we focus our efforts on the Late Permian event, the results will be broadly applicable to other intervals of Earth history as well.The GFDL Modular Ocean Model will be used to study the three-dimensional general circulation of the Late Permian ocean, with atmospheric boundary conditions being provided through collaboration with our colleagues at the University of Wisconsin and University of Chicago. These boundary conditions are expected to yield both vigorous and sluggish thermohaline circulation states. A small number of biogeochemical constituents will be added to this model, allowing us to assess the spatial distribution of anoxia. The circulation fields generated by the 3-D model will then be zonally averaged and used in a 2-D, multi-constituent biogeochemical model to study the biogeochemical consequences of sluggish circulation. In addition to phosphate and oxygen, the 2-D model will calculate distributions of dissolved inorganic carbon, sulfur and strontium isotopic compositions. Thus we will be able to investigate the hypothesis that an invigoration of ocean, releasing toxic amounts of carbon dioxide to the atmosphere, and to compare the predicted and observed isotopic records of such an event. A number of sensitivity analyses will be performed, including the model response to variations in riverine and hydrothermal input, to various kinetic and isotopic parameters, and to the drift of Pangea off the South Pole.