Global Biogeochemical Implications of Oceanic Nitrous Oxide, Oxygen, and Nitrate Deficit Patterns: Model and Data Analysis

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ABSTRACTOCE-00996404The atmospheric concentration of nitrous oxide (N2O), one of the major greenhouses of Earth, has increased since the beginning of global industrialization. The reasons for the increase are not understood, but evidence suggests that as much as 50% the input to the atmosphere derives from the ocean. There is a clear need to constrain the sources and fluxes of marine N2O.In this project researchers at the Scripps Institution of Oceanography and the National Center for Atmospheric research will conduct a model and data analysis study of ocean N2O production, nitrification, and denitrification. The study aims to provide an updated estimate of the ocean N2O source using newly available surface N2O data and gas transfer methods. Both the magnitude and distribution of the ocean source will be examined in this analysis, with particular attention to the importance of coastal and suboxic regions. A second goal of the study is to explore the relationships among ocean N2O, O2 , and nutrients in global and regional data sets. The ocean N2O source predicted by this modeling investigation will be compared to that estimated from surface N2O data using gas transfer methods. Nonconventional mechanisms, including denitrification and N2O production in anoxic microzones of sinking organic matter, will be tested as well. Additional goals of the biogeochemistry/transport model study include estimating how ocean N2O emissions may have changed under past climate conditions and examining how links between the biogeochemical cycles of nitrogen and carbon may lead to correlated variations in ocean N2O and CO2 fluxes.