Airborne observations of trace gases over boreal Canada during BORTAS: campaign climatology, air mass analysis and enhancement ratios

Abstract

Abstract. In situ airborne measurements were made over eastern Canada in summer 2011 as part of the BORTAS experiment (Quantifying the impact of BOReal forest fires on Tropospheric oxidants over the Atlantic using Aircraft and Satellites). In this paper we present observations of greenhouse gases (CO 2 and CH 4 ) and other biomass burning tracers (CO, HCN and CH 3 CN), both climatologically and through case studies, as recorded on board the FAAM BAe-146 research aircraft.Vertical profiles of CO 2 were generally characterised by depleted boundary layer concentrations relative to the free troposphere, consistent with terrestrial biospheric uptake. In contrast, CH 4 concentrations were found to rise with decreasing altitude due to strong local and regional surface sources. BORTAS observations were found to be broadly comparable with both previous measurements in the region during the regional burning season and with reanalysed composition fields from the EU Monitoring Atmospheric Composition and Change (MACC) project. We use coincident tracer-tracer correlations and a Lagrangian trajectory model to characterise and differentiate air mass history of intercepted plumes. In particular, CO, HCN and CH 3 CN were used to identify air masses that have been recently influenced by biomass burning.Examining individual cases we were able to quantify emissions from biomass burning. Using both near-field (< 1 day) and far-field (> 1 day) sampling, boreal forest fire plumes were identified throughout the troposphere. Fresh plumes from fires in northwestern Ontario yield emission factors for CH 4 and CO 2 of 8.5 ± 0.9 g (kg dry matter) −1 and 1512 ± 185 g (kg dry matter) −1 , respectively. We have also investigated the efficacy of calculating emission factors from far-field sampling, in which there might be expected to be limited mixing with background and other characteristic air masses, and we provide guidance on best practice and limitations in such analysis. We have found that for measurements within plumes that originated from fires in northwestern Ontario 2-4 days upwind, emission factors can be calculated that range between 1618 ± 216 and 1702 ± 173 g Published by Copernicus Publications on behalf of the European Geosciences Union. S. J. O'Shea et al.: Airborne observations of trace gases over boreal Canada(kg dry matter) −1 for CO 2 and 1.8 ± 0.2 and 6.1 ± 1 g (kg dry matter) −1 for CH 4 .

Distribution of Trace Gases and Aerosols in the Troposphere Over Siberia During Wildfires of Summer 2012

“…In the layers located in the midtroposphere, the maximal increment can be 1,000 and 1,700 ppb, whereas its average values range within 150-120 ppb. For СО 2 and СН 4 , the obtained estimates are comparable with the data of Basso et al (2016), Bian et al (2013), Law et al (2014), O'Shea et al (2013, Palmer et al (2013), and Virkkula et al (2014), while for СО they exceed the published data.…”

“…The measured concentrations of carbonaceous gases over the territory of Western and Eastern Siberia are quite comparable with or higher than the analogous data for the vertical distributions in other regions (Basso et al, 2016;Bian et al, 2013;Law et al, 2014;O'Shea et al, 2013;Palmer et al, 2013;Virkkula et al, 2014). At the same time, the measured maximal concentrations of CO in the troposphere are smaller than those measured in the surface layer (Elansky et al, 2011;Fokeeva et al, 2011;Kashin et al, 2016;Krol et al, 2013;Zvyagintsev et al, 2011), except for СО 2 .…”

“…However, the method of airborne sensing is characterized by complexity and high costs. That is why such measurements are relatively few (Basso et al, 2016;Bian et al, 2013;Law et al, 2014;O'Shea et al, 2013;Palmer et al, 2013;Virkkula et al, 2014). There is a need to expand the airborne measurements of atmospheric composition study to characterize distribution of biomass burning products emitted by forest fires.…”

Influence of Meteorology and interrelationship with greenhouse gases (CO&lt;sub&gt;2&lt;/sub&gt; and CH&lt;sub&gt;4&lt;/sub&gt;) at a suburban site of India

“…This instrument is well known for high precision and accuracy, both of which are crucial for understanding background concentrations of atmospheric GHGs, with specifications meeting WMO standards of measurement (Berman et al, 2012;Shea et al, 2013;Mahesh et al, 2015). It is based on enhanced off-axis integrated cavity output spectroscopy (OA-ICOS) technology (Paul et al, 2001;Baer et al, 2002), which utilizes true wavelength scanning to record fully resolved absorption line shapes.…”

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

“…Biomass burning plumes transported over the Arctic have been observed by ground-based Fourier transform infrared (FTIR) spectrometers (Yurganov et al, 2004(Yurganov et al, , 2005Viatte et al, 2013), measurements on aircraft (Paris et al, 2009;Warneke et al, 2009;Simpson et al, 2011;Hecobian et al, 2011;Parrington et al, 2013;O'Shea et al, 2013;Le Breton et al, 2013;Lewis et al, 2013), and satellites Coheur et al, 2009;Tereszchuk et al, 2011Tereszchuk et al, , 2013. Model simulations and meteorological analyses also suggest pollution transport pathways to the Arctic (Eckhardt et al, 2003;Klonecki et al, 2003;Koch and Hansen, 2005;Stohl et al, 2006;Shindell et al, 2008;Thomas et al, 2013;Bian et al, 2013).…”