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Published March 2, 2015 | Published
Journal Article Open

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


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 (C_2H_6), acetylene (C_2H_2), formic acid (HCOOH), and formaldehyde (H_2CO) 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 C_2H_6), 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 C_2H_6, 0.34 ± 0.21 g kg^(−1) for C_2H_2, and 2.92 ± 1.30 g kg^(−1) for HCOOH. The emission factor for CH_3OH 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 C_2H_6, 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 H_2CO 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.

Additional Information

© 2015 Author(s). Published by Copernicus Publications on behalf of the European Geosciences Union. This work is distributed under the Creative Commons Attribution 3.0 License. Received: 09 August 2014. Published in Atmos. Chem. Phys. Discuss.: 21 October 2014. Revised: 28 January 2015. Accepted: 30 January 2015. Published: 02 March 2015. Edited by: T. von Clarmann. This work was supported by NSERC. The PEARL Bruker 125HR measurements at Eureka were made by CANDAC, which has been supported by the AIF/NSRIT, CFI, CFCAS, CSA, EC, Government of Canada IPY funding, NSERC, OIT, ORF, PCSP, and FQRNT. The authors wish to thank the staff at the Eureka Weather Station and CANDAC for the logistical and on-site support provided. Thanks to Rodica Lindenmaier, Rebecca Batchelor, PEARL site manager Pierre Fogal, and CANDAC/PEARL operators Ashley Harrett, Alexei Khmel, Paul Loewen, Keith MacQuarrie, Oleg Mikhailov, and Matt Okraszewski, for their invaluable assistance in maintaining the Bruker 125HR and for taking measurements. The National Center for Atmospheric Research is supported by the National Science Foundation. The observation program at Thule, Greenland, is supported under contract by the National Aeronautics and Space Administration and the site is also supported by the NSF Office of Polar Programs. We wish to thank the Danish Meteorological Institute for support at Thule. The authors also acknowledge NOAA-ARL for access to the HYSPLIT trajectory model, and NASA for its MODIS and OMI imagery products available from their Rapidfire website and from the Giovanni online data system, developed and maintained by the NASA GES DISC. The visit of C. Paton-Walsh to the U of T to collaborate on this study was funded by the ARC as part of project DP110101948.

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August 20, 2023
August 20, 2023