Investigation of CO, C<sub>2</sub>H<sub>6</sub> and aerosols in a boreal fire plume over eastern Canada during BORTAS 2011 using ground- and satellite-based observations and model simulations

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.

Properties and evolution of biomass burning organic aerosol from Canadian boreal forest fires

“…CO concentrations of up to 800 ppb were observed between 5000-8000 m, whereas OA did not exceed 30 µg m −3 . This disparity is attributed to the removal of OA from plumes encountered during flight B622 (20 July) by precipitation prior to sampling following advection through clouds, as corroborated by meteorological observations and back trajectory models (Griffin et al, 2013;Taylor et al, 2014). Wet deposition of aerosol reduced OA to background levels, while CO concentrations remained elevated to similar levels as observed at lower altitudes.…”

A case study of aerosol scavenging in a biomass burning plume over eastern Canada during the 2011 BORTAS field experiment

“…As demonstrated in Fig. 7 of Griffin et al (2013), the finemode AOD is generally positively correlated with total column CO throughout the campaign. However, not all measurements of specific air masses follow this trend, and it is one of these exceptions that is investigated in this paper.…”

“…Uncertainties in the derived columns were calculated in a manner similar to that described by Batchelor et al (2009) and Griffin et al (2013). Errors considered in our calculations include the smoothing error, measurement error, uncertainties in the HITRAN 2008 line parameters, and errors in the temperature profile.…”

“…Thus, a proper comparison of the total gas column measurements between the two instruments requires smoothing the DAO-DA8 profiles using the PARIS-IR averaging kernels. This process is detailed in Griffin et al (2013). Total and partial column values are calculated from the retrieved VMR profiles by integrating over the altitude range taking into account the density of the atmosphere at each layer.…”

Comparison of IASI water vapor retrieval with H<sub>2</sub>O-Raman lidar in the framework of the Mediterranean HyMeX and ChArMEx programs

“…The main mission of IASI is operational meteorology (e.g., Zhou et al, 2009), although air-composition and climate applications are also well covered by the instrument as also discussed before launch (e.g., Chazette et al, 1998;Clerbaux et al, 1998) and now demonstrated (e.g., Crevoisier et al, 2013a;Griffin et al, 2013;Grieco et al, 2013). Hereafter we will only discuss the comparison between IASIderived WVMR and the simultaneous measurements performed by a H 2 O-Raman lidar deployed on the Balearic island of Menorca in the framework of the Hydrological cycle in the Mediterranean eXperiment (HyMeX, http: //www.hymex.org/, Chazette et al, 2014) and ChemistryAerosol Mediterranean Experiment (ChArMEx, http://www.…”