Publication Date:
2017-05-19
Description:
We estimate the global ocean N2O flux to the atmosphere and its confidence interval using a statistical method based on model perturbation simulations and their fit to a database of ΔpN2O (n=6136). We evaluate two submodels of N2O production. The first submodel splits N2O production into oxic and hypoxic pathways following previous publications. The second submodel explicitly represents the redox transformations of N that lead to N2O production (nitrification and hypoxic denitrification) and N2O consumption (suboxic denitrification), and is presented here for the first time. We perturb both submodels by modifying the key parameters of the N2O cycling pathways (nitrification rates, NH4+ uptake, N2O yields under oxic, hypoxic and suboxic conditions), and determine a set of optimal model parameters by minimisation of a cost function against 4 databases of N cycle observations derived from observed and model ΔpN2O concentrations. Our estimate of the global oceanic N2O flux resulting from this cost function minimisation is 2.4 ± 0.8 Tg N y−1, and is invariant to the choice of N2O submodel. These estimates suggest that the currently available observational data of surface ΔpN2O constrain the global N2O flux to a narrower range relative to the large range of results presented in the latest IPCC report.
Print ISSN:
1810-6277
Electronic ISSN:
1810-6285
Topics:
Biology
,
Geosciences
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