Source attributions of pollution to the Western Arctic during the NASA ARCTAS field campaign

Abstract

We use the NASA GEOS-5 transport model with tagged tracers to investigate the contributions of different regional sources of CO and black carbon (BC) to their concentrations in the Western Arctic (i.e., 50–90° N and 190–320° E) in spring and summer 2008. The model is evaluated by comparing the results with airborne measurements of CO and BC from the NASA Arctic Research of the Composition of the Troposphere from Aircraft and Satellites (ARCTAS) field campaigns to demonstrate the strengths and limitations of our simulations. We also examine the reliability of tagged CO tracers in characterizing air mass origins using the measured fossil fuel tracer of dichloromethane and the biomass burning tracer of acetonitrile. Our tagged CO simulations suggest that most of the enhanced CO concentrations (above background level from CH₄ production) observed during April originate from Asian anthropogenic emissions. Boreal biomass burning emissions and Asian anthropogenic emissions are of similar importance in July domain wise, although the biomass burning CO fraction is much larger in the area of the ARCTAS field experiments. The fraction of CO from Asian anthropogenic emissions is larger in spring than in summer. European sources make up no more than 10% of CO levels in the campaign domain during either period. Comparisons of CO concentrations along the flight tracks with regional averages from GEOS-5 show that the along-track measurements are representative of the concentrations within the large domain of the Western Arctic in April but not in July

Spatial and seasonal distribution of Arctic aerosols observed by the CALIOP satellite instrument (2006–2012)

“…Bian et al (2013) demonstrated that the ARCTAS measurements along the flight track were representative of regional averages during spring 2008. Figure 6 shows the in situ extinction profiles observed during the April 2008 ARCTAS deployment over the AK region.…”

“…The summer 2008 IPY measurements showed that the East Asian contribution to Arctic CO and aerosols was small, indicating inefficient transport as well as enhanced wet scavenging of aerosols (Matsui et al, 2011;Bian et al, 2013). Despite high plume dilution and stronger wet removal in summer, several aerosol plumes were traced to both fossil-fuel and biomass burning origins, and all showed a preponderant component of highly oxygenated organic carbon compounds (> 70 %) with relatively larger sulfate fractions for plumes originating in industrialized regions (Schmale et al, 2011).…”

“…During these springtime campaigns, several dense biomass burning plumes from agricultural and forest fires in Russia were sampled over the Alaskan and Canadian Arctic (Warneke et al, 2009;Fisher et al, 2010). Source attribution studies have determined that fossil-fuel burning in East Asia was the dominant source of pollution during ARCTAS-A, representing roughly 40 % of Arctic CO at all altitudes Bian et al, 2013), although European and Russian sources also contributed significantly at low altitudes (30 %). Wang et al (2011) reported that sulfate aerosols contributed to 50-70 % of aerosol mass, with organic aerosols accounting for another 30-40 % at all altitudes.…”

Source Sector and Region Contributions to Black Carbon and PM<sub>2.5</sub> in the Arctic

“…There are number of factors including but not limited to the uncertainties in emissions, and the complicated transport pathways from mid-latitudes to the Arctic that contribute to the uncertainties in calculating the impacts of emission sources (Bian et al, 2013;Fuelberg et al, 2010).…”

Estimation of black carbon emissions from Siberian fires using satellite observations of absorption and extinction optical depths

“…Shindell and Faluvegi, 2009;Flanner, 2013;Sand et al, 2013) indicated that a 25 significant part (up to about 50 %) of this temperature increase could have been induced by BC. There is abundant evidence that BB provides a significant contribution to BC in the Arctic atmosphere in the spring and summer (e.g., Stohl, 2006;Stohl et al, 2006;Warneke et al, 2010;Bian et al, 2013). It was also estimated that Siberian fires alone contributed almost half (46 %) of the total BC amount deposited in the Arctic over a period of 12 years (2002)(2003)(2004)(2005)(2006)(2007)(2008)(2009)(2010)(2011)(2012)(2013).…”