- Fisher, JA
- Jacob, DJ
- Travis, KR
- Kim, PS
- Marais, EA
- Miller, C Chan
- Yu, K
- Zhu, L
- Yantosca, RM
- Sulprizio, MP
- Mao, J
- Wennberg, PO
- Crounse, JD
- Teng, AP
- Nguyen, TB
- St Clair, JM
- Cohen, RC
- Romer, P
- Nault, BA
- Wooldridge, PJ
- Jimenez, JL
- Campuzano-Jost, P
- Day, DA
- Hu, W
- Shepson, PB
- Xiong, F
- Blake, DR
- Goldstein, AH
- Misztal, PK
- Hanisco, TF
- Wolfe, GM
- Ryerson, TB
- Wisthaler, A
- Mikoviny, T
- et al.
Formation of organic nitrates (RONO2) during oxidation of biogenic volatile organic compounds (BVOCs: isoprene, monoterpenes) is a significant loss pathway for atmospheric nitrogen oxide radicals (NOx), but the chemistry of RONO2 formation and degradation remains uncertain. Here we implement a new BVOC oxidation mechanism (including updated isoprene chemistry, new monoterpene chemistry, and particle uptake of RONO2) in the GEOS-Chem global chemical transport model with ∼25 × 25 km2 resolution over North America. We evaluate the model using aircraft (SEAC4RS) and ground-based (SOAS) observations of NOx, BVOCs, and RONO2 from the Southeast US in summer 2013. The updated simulation successfully reproduces the concentrations of individual gas- and particle-phase RONO2 species measured during the campaigns. Gas-phase isoprene nitrates account for 25-50% of observed RONO2 in surface air, and we find that another 10% is contributed by gas-phase monoterpene nitrates. Observations in the free troposphere show an important contribution from long-lived nitrates derived from anthropogenic VOCs. During both campaigns, at least 10% of observed boundary layer RONO2 were in the particle phase. We find that aerosol uptake followed by hydrolysis to HNO3 accounts for 60% of simulated gas-phase RONO2 loss in the boundary layer. Other losses are 20% by photolysis to recycle NOx and 15% by dry deposition. RONO2 production accounts for 20% of the net regional NOx sink in the Southeast US in summer, limited by the spatial segregation between BVOC and NOx emissions. This segregation implies that RONO2 production will remain a minor sink for NOx in the Southeast US in the future even as NOx emissions continue to decline.