Surface Ocean - Lower Atmosphere Study (SOLAS) Project Integration

Nitrous oxide (N2O)

Nitrous oxide (N2O) is an important atmospheric trace gas. In the troposphere it acts as a strong greenhouse gas and in the stratosphere it is the major precursor of the ozone-depleting nitric oxide radical. Moreover, the last 100 years have seen a significant increase in atmospheric N2O concentrations. Oceanic N2O emissions play a major role in the atmospheric N2O budget (e.g. Bange, 2006).  

In the 4th assessment report of the Intergovernmental Panel on Climate Change (IPCC), mean annual N2O emissions (ranges are given in parenthesis) of 3.8 (1.8 – 5.8) Tg N and 1.7 (0.5 – 2.9) Tg N were attributed to the open ocean and coastal areas (including rivers), respectively (IPCC, 2007). This represents 21% (open ocean) and 10% (coastal including rivers) of all N2O sources (IPCC, 2007).

There are various reasons for the considerable ranges of uncertainty in the global N2O emission estimates (Bange, 2008):

  1. different methodological approaches (empirical models versus extrapolation of measurements);
  2. the application of different air-sea exchange models;
  3. the fact that the applied classification of coastal areas is not uniform.

Improving our current estimates of marine N2O emissions is therefore a key priority. A recent initiative under COST Action 735, called MEMENTO, aims to integrate existing oceanic and atmospheric measurements into a global database (see Bange et al., 2009). For further details of MEMENTO, please also see the outline document and an article written for the IMBER newsletter. Details concerning the spreadsheets necessary for submission are available, along with instructions for submitting data.

References
  1. Bange, H.W., 2006. New Directions: The importance of oceanic nitrous oxide emissions. Atmospheric Environment, 40(1): 198-199.
  2. Bange, H.W., 2008. Gaseous nitrogen compounds (NO, N2O, N2, NH3) in the ocean. In: D.G. Capone, D.A. Bronk, M.R. Mulhollad and E.J. Carpenter (Editors), Nitrogen in the Marine Environment. Elsevier, Amsterdam, pp. 51-94.
  3. Bange, H.W., Bell, T.G., Cornejo, M., Freing, A., Uher, G., Upstill-Goddard, R.C. and Zhang, G., 2009. MEMENTO: A proposal to develop a database of marine nitrous oxide and methane measurements. Environmental Chemistry, Submitted.
  4. IPCC, 2007. Contribution of Working Group I to the Fourth Assessment Report of the Intergovernmental Panel on Climate Change. In: S. Solomon et al. (Editors), Climate Change 2007: The Physical Science Basis. Cambridge University Press, Cambridge, UK and New York, USA.

Implementation Working Group 3 also examines the following long-lived, climatically active gases:

Carbon dioxide | Methane