Zamora, Lauren, Kock, Annette , Oschlies, Andreas and Bange, Hermann W. (2013) Constraining current oceanic nitrous oxide (N2O) emissions and reducing uncertainty for future emissions. [Talk] In: Goldschmidt Conference 2013. , 25.-30.08.2013, Florence, Italy ; p. 2579 . Mineralogical Magazine, 77 (5).

Abstract

N2O is the third most important greenhouse gas, and the 2007 IPCC estimated that oceans provide 10-30% of annual N2O flux to the atmosphere [1]. The large range in previously estimated oceanic emissions is primarily due to uncertainties in parametrizing microbial N2O production and consumption within the ocean and to spottiness of data coverage. Here we better constrain ocean N2O fluxes to the atmosphere by using a complementary dual data-based and modeling approach. First, we estimate current day emissions from the new MEMENTO database, in which gaps in ocean N2O data coverage have been improved from previous studies [2]. We find oceanic emissions at ~8.6 Tg N2O yr-1, which falls into the higher end of the 2007 IPCC estimate of 2.8-9.1 Tg N2O yr-1 emitted from the ocean [1]. Our estimate falls on the high-end of previous estimates primarily due to better data coverage in oceanic N2O emission hotspots.
The new atmospheric N2O fluxes from the MEMENTO database gives us valuable insight into the importance of oceanic N2O emissions. However, improved estimates of the fluxes alone will not allow predictive capacity for future marine N2O emissions. Therefore, we use the improved present-day emissions estimate calculated here to constrain N2O parameterizations for a marine biogeochemical model.
The marine biogeochemical model incorporates the ranges of literature uncertainties in N2O biological production and consumption and provides the associated N2O emissions.
Given the known range in current-day fluxes, we are now able to better constrain some of the uncertainties in biogeochemical model parameterizations, thereby enabling a better predictive capacity for future N2O emissions from the oceans

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