Aircraft observations of NOy above UK during RONOCO campaign: implication for NOx and ozone production

Reactive nitrogen oxides (NOy) play a key role in the chemistry of the atmosphere determining the levels of tropospheric ozone (O3), oxidation capacity of the atmosphere and secondary organic aerosol (SOA). In order to understand large-scale (regional to global) NOy chemistry, the knowledge of geographical patterns of the NOy budget and partitioning is needed. During RONOCO (ROle of Nighttime chemistry in controlling the Oxidising Capacity) campaigns (summer 2010 and winter 2011) a comprehensive group of NOy (NO, NO2, HNO3, total peroxy nitrates (ΣRO2NO2), total alkyl nitrates (ΣRONO2), N2O5 NO3, PAN) were measured on board the FAAM aircraft BAe-146. Distribution and partitioning of measured reactive nitrogen and its relationship with ozone under different conditions: nighttime, daytime, polluted and clean air, will be described. Observational NOy are also compared with simulations from a chemical box model to assess sources and sinks of reactive nitrogen, our present knowledge of O3 and SOA photochemical production.