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Atmospheric Chemistry and Physics An interactive open-access journal of the European Geosciences Union
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Volume 15, issue 5
Atmos. Chem. Phys., 15, 2227–2246, 2015
© Author(s) 2015. This work is distributed under
the Creative Commons Attribution 3.0 License.
Atmos. Chem. Phys., 15, 2227–2246, 2015
© Author(s) 2015. This work is distributed under
the Creative Commons Attribution 3.0 License.

Research article 02 Mar 2015

Research article | 02 Mar 2015

Identifying fire plumes in the Arctic with tropospheric FTIR measurements and transport models

C. Viatte1,*, K. Strong1, J. Hannigan2, E. Nussbaumer2, L. K. Emmons2, S. Conway1, C. Paton-Walsh3, J. Hartley1, J. Benmergui4,**, and J. Lin4,5 C. Viatte et al.
  • 1Department of Physics, University of Toronto, Toronto, ON, Canada
  • 2National Center for Atmospheric Research, Boulder, CO, USA
  • 3Department of Chemistry, University of Wollongong, Wollongong, New South Wales, Australia
  • 4Department of Earth and Environmental Sciences, University of Waterloo, Waterloo, ON, Canada
  • 5Department of Atmospheric Sciences, University of Utah, Salt Lake City, UT, USA
  • *now at: Division of Geological and Planetary Sciences, California Institute of Technology, Pasadena, CA, USA
  • **now at: School of Engineering and Applied Sciences, Harvard University, Cambridge, MA, USA

Abstract. We investigate Arctic tropospheric composition using ground-based Fourier transform infrared (FTIR) solar absorption spectra, recorded at the Polar Environment Atmospheric Research Laboratory (PEARL, Eureka, Nunavut, Canada, 80°05' N, 86°42' W) and at Thule (Greenland, 76°53' N, −68°74' W) from 2008 to 2012. The target species, carbon monoxide (CO), hydrogen cyanide (HCN), ethane (C2H6), acetylene (C2H2), formic acid (HCOOH), and formaldehyde (H2CO) are emitted by biomass burning and can be transported from mid-latitudes to the Arctic.

By detecting simultaneous enhancements of three biomass burning tracers (HCN, CO, and C2H6), ten and eight fire events are identified at Eureka and Thule, respectively, within the 5-year FTIR time series. Analyses of Hybrid Single Particle Lagrangian Integrated Trajectory (HYSPLIT) model back-trajectories coupled with Moderate Resolution Imaging Spectroradiometer (MODIS) fire hotspot data, Stochastic Time-Inverted Lagrangian Transport (STILT) model footprints, and Ozone Monitoring Instrument (OMI) UV aerosol index maps, are used to attribute burning source regions and travel time durations of the plumes. By taking into account the effect of aging of the smoke plumes, measured FTIR enhancement ratios were corrected to obtain emission ratios and equivalent emission factors. The means of emission factors for extratropical forest estimated with the two FTIR data sets are 0.40 ± 0.21 g kg−1 for HCN, 1.24 ± 0.71 g kg−1 for C2H6, 0.34 ± 0.21 g kg−1 for C2H2, and 2.92 ± 1.30 g kg−1 for HCOOH. The emission factor for CH3OH estimated at Eureka is 3.44 ± 1.68 g kg−1.

To improve our knowledge concerning the dynamical and chemical processes associated with Arctic pollution from fires, the two sets of FTIR measurements were compared to the Model for OZone And Related chemical Tracers, version 4 (MOZART-4). Seasonal cycles and day-to-day variabilities were compared to assess the ability of the model to reproduce emissions from fires and their transport. Good agreement in winter confirms that transport is well implemented in the model. For C2H6, however, the lower wintertime concentration estimated by the model as compared to the FTIR observations highlights an underestimation of its emission. Results show that modeled and measured total columns are correlated (linear correlation coefficient r > 0.6 for all gases except for H2CO at Eureka and HCOOH at Thule), but suggest a general underestimation of the concentrations in the model for all seven tropospheric species in the high Arctic.

Publications Copernicus
Short summary
Seven tropospheric species (CO, HCN, C2H6, C2H2, CH3OH, HCOOH, and H2CO) released by biomass burning events transported to the high Arctic were monitored with two sets of FTIR measurements, located at Eureka (Nunavut, Canada) and Thule (Greenland), from 2008 to 2012. We compared these data sets with the MOZART-4 chemical transport model to help improve its simulations in the Arctic. Emission factors of these biomass burning products were derived and compared to the literature.
Seven tropospheric species (CO, HCN, C2H6, C2H2, CH3OH, HCOOH, and H2CO) released by biomass...
Final-revised paper