Heterogeneous Atmospheric Chemistry of Nitrogen Oxides: New Insights from Recent Field Measurements

Abstract

The heterogeneous chemistry of nitrogen oxides that occurs in the dark is important to both the overall budgets of reactive nitrogen in the atmosphere, as well as the formation of oxidants. Two of the most relevant processes include the conversion of NO2 to HONO on ground surfaces and the uptake of N2O5 to produce either HNO3 or ClNO2 on aerosol surfaces. Results from recent field measurements that have investigated the latter process have demonstrated several important findings. First, the uptake of N2O5 is highly variable, and the uptake coefficient, γ(N2O5), is often smaller than model parameterizations based on laboratory studies would suggest. Second, production of ClNO2 is much more efficient than previously thought, and is formed in relatively high yields even at interior continental sites that are well removed from direct sources of sea spray. Finally, N2O5 uptake and ClNO2 production both vary strongly with height in the nocturnal boundary layer, leading to significant complexity in this nighttime chemistry. © Springer Science+Business Media Dordrecht 2013.