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Biomass Burning Smoke Influences Clouds over the Western U. S.
  • +11
  • Cynthia H. Twohy,
  • Darin W. Toohey,
  • Ezra J.T. Levin,
  • Paul J DeMott,
  • Bryan Rainwater,
  • Lauren A. Garofalo,
  • Matson A. Pothier,
  • Delphine Farmer,
  • Sonia M. Kreidenweis,
  • Rudra Prasad Pokhrel,
  • Shane Murphy,
  • J. Michael Reeves,
  • Kathryn A Moore,
  • Emily V Fischer
Cynthia H. Twohy
Northwest Research Associates

Corresponding Author:[email protected]

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Darin W. Toohey
University of Colorado Boulder
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Ezra J.T. Levin
Handix Scientific
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Paul J DeMott
Colorado State University
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Bryan Rainwater
University of Colorado Boulder
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Lauren A. Garofalo
Department of Chemistry, Colorado State University
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Matson A. Pothier
Department of Chemistry, Colorado State University
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Delphine Farmer
Colorado State University
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Sonia M. Kreidenweis
Colorado State University
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Rudra Prasad Pokhrel
North Carolina A & T State University
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Shane Murphy
University of Wyoming
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J. Michael Reeves
National Center for Atmospheric Research (UCAR)
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Kathryn A Moore
Colorado State University
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Emily V Fischer
Colorado State University
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Abstract

Small cumulus clouds over the western United States were measured via airborne instruments during the wildfire season in summer of 2018. Statistics of the sampled clouds are presented and compared to smoke aerosol properties. Cloud droplet concentrations were enhanced in regions impacted by biomass burning smoke, at times exceeding 3,000 cm-3. Images and elemental composition of individual smoke particles and cloud droplet residuals are presented and show that most are dominantly organic, internally mixed with some inorganic elements. Despite their high organic content and relatively low hygroscopicity, on average about half of smoke aerosol particles >80 nm diameter formed cloud droplets. This reduced cloud droplet size in small, smoke-impacted clouds. A number of complex and competing climatic impacts may result from wide-spread reductions in cloud droplet size due to wildfires prevalent across the region during summer months.