Final report on international comparison CCQM-K68: Nitrous oxide in synthetic air

Nitrous oxide (N2O) is one of six greenhouse gases that are regulated by the Kyoto Protocol and has a Global Warming Potential (GWP) that is 296 times that of carbon dioxide. Global levels of nitrous oxide have increased at a rate of 0.25%/yr (0.8 ppb/yr) during the last ten years. In order to monitor levels of nitrous oxide in the atmosphere, it is necessary to use measurement standards with demonstrated equivalence at the highest level of accuracy. This report describes the results of a key comparison of standard gas mixtures of nitrous oxide in synthetic air at an amount fraction of 320 nmol/mol. This key comparison is part of the programme of the Gas Analysis Working Group (GAWG) of the CCQM to demonstrate the equivalence of the standards and measurement capabilities of the NMIs for greenhouse gases. It will support the development of measurement capability at the NMIs for nitrous oxide with uncertainties within the target set by the Global Atmospheric Watch (GAW) programme of the WMO for its global monitoring networks. Main text. To reach the main text of this paper, click on Final Report. Note that this text is that which appears in Appendix B of the BIPM key comparison database kcdb.bipm.org/. The final report has been peer-reviewed and approved for publication by the CCQM, according to the provisions of the CIPM Mutual Recognition Arrangement (MRA).