Abstract
Abstract. We present the results of total column measurements of CO, C2H6 and fine-mode aerosol optical depth (AOD) during the "Quantifying the impact of BOReal forest fires on Tropospheric oxidants over the Atlantic using Aircraft and Satellites" (BORTAS-B) campaign over eastern Canada. Ground-based observations, using Fourier transform spectrometers (FTSs) and sun photometers, were carried out in July and August 2011. These measurements were taken in Halifax, Nova Scotia, which is an ideal location to monitor the outflow of boreal fires from North America, and also in Toronto, Ontario. Measurements of fine-mode AOD enhancements were highly correlated with enhancements in coincident trace gas (CO and C2H6) observations between 19 and 21 July 2011, which is typical for a smoke plume event. In this paper, we focus on the identification of the origin and the transport of this smoke plume. We use back trajectories calculated by the Canadian Meteorological Centre as well as FLEXPART forward trajectories to demonstrate that the enhanced CO, C2H6 and fine-mode AOD seen near Halifax and Toronto originated from forest fires in northwestern Ontario that occurred between 17 and 19 July 2011. In addition, total column measurements of CO from the satellite-borne Infrared Atmospheric Sounding Interferometer (IASI) have been used to trace the smoke plume and to confirm the origin of the CO enhancement. Furthermore, the enhancement ratio – that is, in this case equivalent to the emission ratio (ERC2H6/CO) – was estimated from these ground-based observations. These C2H6 emission results from boreal fires in northwestern Ontario agree well with C2H6 emission measurements from other boreal regions, and are relatively high compared to fires from other geographical regions. The ground-based CO and C2H6 observations were compared with outputs from the 3-D global chemical transport model GEOS-Chem, using the Fire Locating And Modeling of Burning Emissions (FLAMBE) inventory. Agreement within the stated measurement uncertainty (~3% for CO and ~8% for C2H6) was found for the magnitude of the enhancement of the CO and C2H6 total columns between the measured and modelled results. However, there is a small shift in time (of approximately 6 h) of arrival of the plume over Halifax between the results.
Highlights
Large amounts of trace gases as well as aerosols are released from biomass burning
The Fire Locating And Modeling of Burning Emissions (FLAMBE) inventory (Reid et al, 2009) was used to estimate the location and the total carbon emissions from boreal fires during the BORTAS-B campaign in 2011. This inventory provides hourly estimates of carbon and aerosol emissions based on observations from the Geostationary Operational Environmental Satellite (GOES) platforms and the two Moderate Resolution Imaging Spectrometers (MODIS) on the NASA EOS Terra and Aqua satellites
Assuming a wind speed of 10– 15 m s−1, the approximate time it takes for smoke plumes originating from eastern Siberia and northwestern Ontario to reach Halifax is of the order of one week and 1–2 days, respectively
Summary
Large amounts of trace gases as well as aerosols are released from biomass burning These emissions affect air quality and tropospheric and stratospheric chemistry, which has an important impact on the radiative transfer in the atmosphere (Crutzen and Andreae, 1990). There are several species of interest which are present in boreal fire plumes and are indicators of smoke plumes (Tereszchuk et al, 2011); we will focus in our study on carbon monoxide (CO) and ethane (C2H6) as well as finemode aerosols All of these species have a relatively long lifetime in the troposphere and can, be detected up to several thousand kilometres away from the fire source. Fine-mode aerosols of a medium size (approximately 0.15 μm) are removed from the troposphere by wet deposition, and their lifetime is limited by precipitation. Trace gases (CO and C2H6) and the fine-mode aerosol optical depth (AOD) should be highly correlated within fire plumes that are less than 3–5 days old (where this is limited by the lifetime of the aerosols)
Sign-in/Register to view highlights & summary Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
