Feedbacks between N2 fixation and denitrification in a non-Redfield Earth system model and impacts on the oceanic fixed-N inventory in a changing climate

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How and how strongly marine N2 fixation and denitrification are coupled to each other is key to understanding and projecting the oceanic NO3 – inventory and biological pump in a changing climate. While current modeling works predict a strong coupling between N2 fixation and denitrification, the recently developed optimality-based non-Redfield ecosystem model (OPEM) coupled to the UVic- ESCM shows much weaker coupling between them. This project aims to identify those factors and mechanisms that control the coupling, and to understand how the coupling might change in different climate settings. The new model will be applied to pre-industrial, the last glacial maximum and present-day conditions to evaluate the model in terms of the sensitivity of the oceanic nitrogen inventory and the biological carbon pump to different climate states. The ultimate goal is to better understand the controls on the oceanic nitrogen inventory and to provide improved projections of future marine biogeochemistry and its impacts on atmospheric pCO2.