Atmos. Chem. Phys. Discuss., 13, 1795-1853, 2013
www.atmos-chem-phys-discuss.net/13/1795/2013/
doi:10.5194/acpd-13-1795-2013
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This discussion paper has been under review for the journal Atmospheric Chemistry and Physics (ACP). Please refer to the corresponding final paper in ACP.
Ozone photochemistry in boreal biomass burning plumes
M. Parrington1, P. I. Palmer1, A. C. Lewis2, J. D. Lee2, A. R. Rickard3,*, P. Di Carlo4,5, J. W. Taylor6, J. R. Hopkins2, S. Punjabi7, D. E. Oram8, G. Forster8, E. Aruffo4,5, S. J. Moller2, S. J.-B. Bauguitte9, J. D. Allan6,10, H. Coe6, and R. J. Leigh11
1School of GeoSciences, The University of Edinburgh, Edinburgh, UK
2National Centre for Atmospheric Science, Department of Chemistry, University of York, York, UK
3National Centre for Atmospheric Science, School of Chemistry, University of Leeds, UK
4Center of Excellence CETEMPS, University of L'Aquila, L'Aquila, Italy
5Department of Physical and Chemical Sciences, University of L'Aquila, L'Aquila, Italy
6School of Earth, Atmospheric and Environmental Sciences, University of Manchester, Manchester, UK
7Department of Chemistry, University of York, York, UK
8National Centre for Atmospheric Science, School of Environmental Sciences, University of East Anglia, Norwich, UK
9Facility for Airborne Atmospheric Measurements, Bedford, UK
10National Centre for Atmospheric Science, University of Manchester, Manchester, UK
11Department of Physics and Astronomy, University of Leicester, Leicester, UK
*now at: the National Centre for Atmospheric Science, Department of Chemistry, University of York, York, UK

Abstract. We present an analysis of ozone photochemistry observed by aircraft measurements of boreal biomass burning plumes over Eastern Canada in the summer of 2011. Measurements of ozone and a number of key chemical species associated with ozone photochemistry, including non-methane hydrocarbons (NMHCs), nitrogen oxides (NOx) and total nitrogen containing species (NOy), were made from the UK FAAM BAe-146 research aircraft as part of the quantifying the impact of BOReal forest fires on tropospheric oxidants over the Atlantic using Aircraft and Satellites (BORTAS) experiment between 12 July and 3 August 2011. We found that ozone mixing ratios measured in biomass burning plumes were indistinguishable from non-plume measurements, but evaluating them in relationship to measurements of carbon monoxide (CO), total alkyl nitrates (ΣAN) and the surrogate species NOz (=NOy - NOx) revealed that the potential for ozone production increased with plume age. We used NMHC ratios to estimate photochemical ages of the observed biomass burning plumes between 0 and 15 days. Ozone production, calculated from ΔO3/ΔCO enhancement ratios, increased from 0.020 ± 0.008 ppbv ppbv−1 in plumes with photochemical ages less than 2 days to 0.55 ± 0.29 ppbv ppbv−1 in plumes with photochemical ages greater than 5 days. In comparing ozone mixing ratios with components of the NOy budget we observed that plumes with ages between 2 and 4 days were characterised by high aerosol loading, relative humidity greater than 40%, and low ozone production efficiencies of 8 ppbv ppbv−1 relative to ΣAN and 2 ppbv ppbv−1 relative to NOz. In plumes with ages greater than 4 days, ozone production efficiency increased to 473 ppbv ppbv−1 relative to ΣAN and 155 ppbv ppbv−1 relative to NOz. From the BORTAS measurements we estimated that aged plumes with low aerosol loading were close to being in photostationary steady state and ozone production in younger plumes was inhibited by high aerosol loading and greater production of ΣAN relative to ozone. The BORTAS measurements of ozone photochemistry in boreal biomass burning plumes were found to be consistent with previous summertime aircraft measurements made over the same region during the Arctic Research of the Composition of the troposphere (ARCTAS-B) in 2008 and Atmospheric Boundary Layer Experiment (ABLE 3B) in 1990.

Citation: Parrington, M., Palmer, P. I., Lewis, A. C., Lee, J. D., Rickard, A. R., Di Carlo, P., Taylor, J. W., Hopkins, J. R., Punjabi, S., Oram, D. E., Forster, G., Aruffo, E., Moller, S. J., Bauguitte, S. J.-B., Allan, J. D., Coe, H., and Leigh, R. J.: Ozone photochemistry in boreal biomass burning plumes, Atmos. Chem. Phys. Discuss., 13, 1795-1853, doi:10.5194/acpd-13-1795-2013, 2013.
 
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