NOAA's Global Network of N2O Observations

Abstract:

Nitrous oxide has surpassed CFC-12 to become the third largest contributor to radiative forcing. When climate impacts for equal emitted masses of N₂O and CO₂ are integrated over 100 years, N₂O impacts are about 300 times greater than those of CO₂. Increasing the atmospheric burden of N₂O also decreases the abundance of O₃ in the stratosphere. With reductions in emissions of ODSs as a result of the Montreal Protocol, N₂O now has the largest ODP-weighted emissions of all gases. Given its long lifetime of about 130 years, today's emissions will impact climate and stratospheric O₃ for a long time. Because emission rates are very small and spread over enormous areas, the detailed N₂O budget has large uncertainties. It also means measurement requirements on precision and accuracy are stringent, especially for the background atmosphere. The Carbon Cycle Group of NOAA ESRL's Global Monitoring Division began measuring N₂O in discrete air samples collected as part of its global cooperative air sampling network in 1998. Data from about 60 air sampling sites provide important constraints on the large-scale budget of N₂O and provide boundary conditions for continental and regional-scale studies. This presentation will briefly describe the procedures used to ensure the data are of sufficient quality to meet scientific demands, and describe remaining limitations. Although sampling is infrequent (weekly), the data are quite useful in N₂O budget studies. Examples will be given of large scale constraints on N₂O's budget, including the global burden, trends in the burden, global emissions, spatial distributions, vertical gradients, and seasonal patterns.