Organic nitrate chemistry and its implications for nitrogen budgets in an isoprene- and monoterpene-rich atmosphere: constraints from aircraft (SEAC^4RS) and ground-based (SOAS) observations in the Southeast US
Abstract
Formation of organic nitrates (RONO_2) during oxidation of biogenic volatile organic compounds (BVOCs: isoprene, monoterpenes) is a significant loss pathway for atmospheric nitrogen oxide radicals (NO_x), but the chemistry of RONO_2 formation and degradation remains uncertain. Here we implement a new BVOC oxidation mechanism (including updated isoprene chemistry, new monoterpene chemistry, and particle uptake of RONO_2) in the GEOS-Chem global chemical transport model with ∼ 25 × 25 km^2 resolution over North America. We evaluate the model using aircraft (SEAC^4RS) and ground-based (SOAS) observations of NO_x, BVOCs, and RONO_2 from the Southeast US in summer 2013. The updated simulation successfully reproduces the concentrations of individual gas- and particle-phase RONO_2 species measured during the campaigns. Gas-phase isoprene nitrates account for 25–50 % of observed RONO_2 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 RONO_2 were in the particle phase. We find that aerosol uptake followed by hydrolysis to HNO_3 accounts for 60 % of simulated gas-phase RONO_2 loss in the boundary layer. Other losses are 20 % by photolysis to recycle NO_x and 15 % by dry deposition. RONO_2 production accounts for 20 % of the net regional NO_x sink in the Southeast US in summer, limited by the spatial segregation between BVOC and NO_x emissions. This segregation implies that RONO_2 production will remain a minor sink for NO_x in the Southeast US in the future even as NO_x emissions continue to decline.
Additional Information
© Author(s) 2016. This work is distributed under the Creative Commons Attribution 3.0 License. Received: 18 January 2016. Published in Atmos. Chem. Phys. Discuss.: 4 February 2016. Revised: 27 April 2016. Accepted: 29 April 2016. Published: 17 May 2016. We are grateful to the entire NASA SEAC4RS team for their help in the field, and we thank Eleanor Browne and Fabien Paulot for helpful discussions about the monoterpene nitrate scheme. This work was funded by a University of Wollongong Vice Chancellor's Postdoctoral Fellowship to J. A. Fisher and by the NASA Tropospheric Chemistry Program. This research was undertaken with the assistance of resources provided at the NCI National Facility systems at the Australian National University through the National Computational Merit Allocation Scheme supported by the Australian Government. J. Mao acknowledges supports from the NOAA Climate Program Office grant NA13OAR4310071. J. L. Jimenez, P. Campuzano-Jost, W. Hu, and D. A. Day were supported by NASA NNX15AH33A and NNX15AT96G, NSF AGS-1243354 and AGS-1360834, and EPRI 10004734. Isoprene and monoterpene measurements during SEAC4RS were supported by the Austrian Federal Ministry for Transport, Innovation and Technology (bmvit) through the Austrian Space Applications Programme (ASAP) of the Austrian Research Promotion Agency (FFG). A. Wisthaler and T. Mikoviny received support from the Visiting Scientist Program at the National Institute of Aerospace (NIA).Attached Files
Published - acp-16-5969-2016.pdf
Accepted Version - nihms952687.pdf
Supplemental Material - acp-16-5969-2016-supplement.pdf
Files
Additional details
- PMCID
- PMC5906813
- Eprint ID
- 68657
- Resolver ID
- CaltechAUTHORS:20160624-104423152
- University of Wollongong
- Australian Government
- National Oceanic and Atmospheric Administration (NOAA)
- NA13OAR4310071
- NASA
- NNX15AH33A
- NASA
- NNX15AT96G
- NSF
- AGS-1243354
- NSF
- AGS-1360834
- NSF
- EPRI 10004734
- Bundesministerium für Verkehr, Innovation und Technologie (BMVIT)
- Austrian Space Applications Programme (ASAP)
- Austrian Research Promotion Agency (FFG)
- National Institute of Aerospace (NIA)
- Created
-
2016-06-24Created from EPrint's datestamp field
- Updated
-
2021-11-11Created from EPrint's last_modified field
- Caltech groups
- Division of Geological and Planetary Sciences