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Title: Cross-polar transport and scavenging of Siberian aerosols containing black carbon during the 2012 ACCESS summer campaign

During the ACCESS airborne campaign in July 2012, extensive boreal forest fires resulted in significant aerosol transport to the Arctic. A 10-day episode combining intense biomass burning over Siberia and low-pressure systems over the Arctic Ocean resulted in efficient transport of plumes containing black carbon (BC) towards the Arctic, mostly in the upper troposphere (6–8 km). Here, a combination of in situ observations (DLR Falcon aircraft), satellite analysis and WRF-Chem simulations is used to understand the vertical and horizontal transport mechanisms of BC with a focus on the role of wet removal. Between the northwestern Norwegian coast and the Svalbard archipelago, the Falcon aircraft sampled plumes with enhanced CO concentrations up to 200 ppbv and BC mixing ratios up to 25 ng kg –1. During transport to the Arctic region, a large fraction of BC particles are scavenged by two wet deposition processes, namely wet removal by large-scale precipitation and removal in wet convective updrafts, with both processes contributing almost equally to the total accumulated deposition of BC. Our results underline that applying a finer horizontal resolution (40 instead of 100 km) improves the model performance, as it significantly reduces the overestimation of BC levels observed at a coarser resolutionmore » in the mid-troposphere. According to the simulations at 40 km, the transport efficiency of BC (TE BC) in biomass burning plumes was larger (60 %), because it was impacted by small accumulated precipitation along trajectory (1 mm). In contrast TE BC was small (< 30 %) and accumulated precipitation amounts were larger (5–10 mm) in plumes influenced by urban anthropogenic sources and flaring activities in northern Russia, resulting in transport to lower altitudes. TE BC due to large-scale precipitation is responsible for a sharp meridional gradient in the distribution of BC concentrations. Wet removal in cumulus clouds is the cause of modeled vertical gradient of TE BC, especially in the mid-latitudes, reflecting the distribution of convective precipitation, but is dominated in the Arctic region by the large-scale wet removal associated with the formation of stratocumulus clouds in the planetary boundary layer (PBL) that produce frequent drizzle.« less
ORCiD logo [1] ;  [2] ;  [3] ;  [1] ; ORCiD logo [4] ;  [1] ; ORCiD logo [3] ;  [5] ;  [3] ;  [4] ;  [1] ;  [1] ;  [5]
  1. Sorbonne Univ., Paris (France)
  2. Sorbonne Univ., Paris (France); Center for International Climate and Environmental Research, Oslo (Norway)
  3. Pacific Northwest National Lab. (PNNL), Richland, WA (United States)
  4. Institut fur Physik der Atmosphare, Oberpfaffenhofen (Germany); Ludwig-Maximilians-Univ., Munich (Germany); Univ. of Vienna, Vienna (Austria)
  5. Institut fur Physik der Atmosphare, Oberpfaffenhofen (Germany)
Publication Date:
Report Number(s):
Journal ID: ISSN 1680-7324; KP1701000
Grant/Contract Number:
AC05-76RL01830; VH-NG-606
Accepted Manuscript
Journal Name:
Atmospheric Chemistry and Physics (Online)
Additional Journal Information:
Journal Name: Atmospheric Chemistry and Physics (Online); Journal Volume: 17; Journal Issue: 18; Journal ID: ISSN 1680-7324
European Geosciences Union
Research Org:
Pacific Northwest National Lab. (PNNL), Richland, WA (United States)
Sponsoring Org:
USDOE; European Union (EU)
Country of Publication:
United States
OSTI Identifier: