"What Controls the Surface Ocean Iron Distribution? A Modeling Study".

人们越来越认识到铁在海洋生物地球化学循环中的关键作用，它限制了初级生产，并可能限制铁的出口和固氮。由于对海洋铁的分布和形态以及控制它的过程的认识不断增加，开发和检查海洋铁循环的数值模型是及时的。数值模型提供了一种方法来概括群落对生物地球化学循环的理解，并检查这种理解是否与现有数据一致（即模型能否再现数据的关键特征）。这种模式也可用于探索系统对强迫、参数化或参数值变化的敏感性。在这项研究中，麻省理工学院的研究人员将继续进行初步的模型研究，在三维海洋GCM的框架下，进一步发展、限制和探索海洋铁循环的数值模型。科学家小组将进行敏感性测试，以确定哪些是最重要的过程，以及它们如何对不断变化的物理和生物地球化学强迫作出反应。具体来说，将解决五个化学，物理和生物问题：什么是最佳条件稳定性常数和清除率，使基于络合的铁模型与观测数据一致；表面光化学、胶体的形成和铁的沉淀的影响是否可以参数化？这些过程在确定铁的分布和可用性方面是否有重要作用？风成铁在不同地区的可用性（或溶解度）有何影响？铁和磷的表面分布对模拟海洋环流的准确性有多敏感；铁的分布对生态系统和多种潜在限制性营养物质相互作用的细节很敏感。作为这项研究的高潮，一个“最好的”循环和铁生物地球化学模型将被用来检验时变物理和生物地球化学强迫和边界条件在调节海洋铁循环中的作用。最后，科学家小组将研究海洋生物地球化学和海气通量的影响。

ABSTRACTOCE- 0350672There is an increasing awareness of the key role of iron in ocean biogeochemical cycles, limiting primary production and potentially limiting export and nitrogen fixation. Due to increasing knowledge of distribution and speciation of oceanic iron, and of the processes that control it, it is timely to develop and examine numerical models of the ocean iron cycle. Numerical models provide one means by which to encapsulate the communities understanding of biogeochemical cycles and examine if this understanding is consistent with the available data (i.e. can the model reproduce the key features of the data). Such models may also be used to explore the sensitivities of the system to changes in forcing, parameterizations or parameter values.In this study, researchers at the Massachusetts Institute of Technology will continue the preliminary model studies by further developing, constraining, and exploring numerical models of the ocean iron cycle with the framework of a three-dimensional ocean GCM. The team of scientists will perform sensitivity tests to determine which are the most significant processes and how they respond to changing physical and biogeochemical forcing. Specifically, five chemical, physical and biological questions will be addressed: what are the optimal conditional stability constants and scavenging rates which bring the complexation based iron model into consistency with observed data; can the effects of surface photochemistry, the formation of colloids, and precipitation of iron be parameterized; do these processes have a significant role in setting the distribution and availability of iron; what is the impact of regionally varying availability (or solubility) of iron of aeolian origin; how sensitive is the surface distribution of iron and phosphorus to the veracity of the modeled ocean circulation; is the distribution of iron sensitive to details of the interactions of the ecosystem and multiple potentially limiting nutrients. As the culmination of this study a "best-shot" circulation and iron biogeochemistry model will be used to examine the role of time-varying physical and biogeochemical forcing and boundary conditions in modulating the ocean iron cycle. Finally, the team of scientists will examine the consequences for ocean biogeochemistry and air-sea gas fluxes.