1Department of Physics and Atmospheric Science, Dalhousie University, Halifax, Nova Scotia, Canada
2Department of Physics, University of Toronto, Toronto, Ontario, Canada
3Department of Atmospheric Science, Colorado State University, Ft. Collins, CO, USA
4Meteorological Service of Canada, Dartmouth, Nova Scotia, Canada
5School of GeoSciences, University of Edinburgh, Edinburgh, UK
6National Centre for Atmospheric Science (NCAS), Department of Chemistry, University of York, York, UK
7National Centre for Atmospheric Science (NCAS), School of Chemistry, University of Leeds, Leeds, UK
8Centre for Atmospheric Science, School of Earth, Atmospheric and Environmental Sciences, University of Manchester, Manchester, UK
9National Centre for Atmospheric Science, University of Manchester, Manchester, UK
10Laboratoire Atmosphères, Milieux, Observations Spatiales, UPMC-UVSQ-CNRS, Paris, France
11Department of Process Engineering and Applied Science, Dalhousie University, Halifax, Nova Scotia, Canada
12CARTEL, Universite de Sherbrooke, Sherbrooke, Quebec, Canada
*now at: European Centre for Medium-Range Weather Forecasts, Reading, UK
**now at: National Centre for Atmospheric Science (NCAS), Department of Chemistry, University of York, York, UK
Received: 13 Jan 2014 – Discussion started: 06 Feb 2014
Abstract. We present measurements of a long-range smoke transport event recorded on 20–21 July 2011 over Halifax, Nova Scotia, Canada, during the Quantifying the impact of BOReal forest fires on Tropospheric oxidants over the Atlantic using Aircraft and Satellites (BORTAS-B) campaign. Ground-based Fourier transform spectrometers and photometers detected air masses associated with large wildland fires burning in eastern Manitoba and western Ontario.
Revised: 04 Jun 2014 – Accepted: 18 Jun 2014 – Published: 21 Aug 2014
We investigate a plume with high trace gas amounts but low amounts of particles that preceded and overlapped at the Halifax site with a second plume with high trace gas loadings and significant amounts of particulate material. We show that the first plume experienced a meteorological scavenging event, but the second plume had not been similarly scavenged. This points to the necessity to account carefully for the plume history when considering long-range transport since simultaneous or near-simultaneous times of arrival are not necessarily indicative of either similar trajectories or meteorological history. We investigate the origin of the scavenged plume, and the possibility of an aerosol wet deposition event occurring in the plume ~ 24 h prior to the measurements over Halifax. The region of lofting and scavenging is only monitored on an intermittent basis by the present observing network, and thus we must consider many different pieces of evidence in an effort to understand the early dynamics of the plume. Through this discussion we also demonstrate the value of having many simultaneous remote-sensing measurements in order to understand the physical and chemical behaviour of biomass burning plumes.
Franklin, J. E., Drummond, J. R., Griffin, D., Pierce, J. R., Waugh, D. L., Palmer, P. I., Parrington, M., Lee, J. D., Lewis, A. C., Rickard, A. R., Taylor, J. W., Allan, J. D., Coe, H., Walker, K. A., Chisholm, L., Duck, T. J., Hopper, J. T., Blanchard, Y., Gibson, M. D., Curry, K. R., Sakamoto, K. M., Lesins, G., Dan, L., Kliever, J., and Saha, A.: A case study of aerosol scavenging in a biomass burning plume over eastern Canada during the 2011 BORTAS field experiment, Atmos. Chem. Phys., 14, 8449-8460, doi:10.5194/acp-14-8449-2014, 2014.