Effects of Biomass Burning on Stratocumulus Droplet Characteristics, Drizzle Rate, and Composition

Ali Hossein Mardi, Hossein Dadashazar, Alexander B. MacDonald, Ewan Crosbie, Matthew M. Coggon, Mojtaba Azadi Aghdam, Roy K. Woods, Haflidi H. Jonsson, Richard C. Flagan, John H. Seinfeld, Armin Sorooshian

Research output: Contribution to journalArticle

4 Scopus citations

Abstract

This study reports on airborne measurements of stratocumulus cloud properties under varying degrees of influence from biomass burning (BB) plumes off the California coast. Data are reported from five total airborne campaigns based in Marina, California, with two of them including influence from wildfires in different areas along the coast of the western United States. The results indicate that subcloud cloud condensation nuclei number concentration and mass concentrations of important aerosol species (organics, sulfate, nitrate) were better correlated with cloud droplet number concentration (Nd) as compared to respective above-cloud aerosol data. Given that the majority of BB particles resided above cloud tops, this is an important consideration for future work in the region as the data indicate that the subcloud BB particles likely were entrained from the free troposphere. Lower cloud condensation nuclei activation fractions were observed for BB-impacted clouds as compared to non-BB clouds due, at least partly, to less hygroscopic aerosols. Relationships between Nd and either droplet effective radius or drizzle rate are preserved regardless of BB influence, indicative of how parameterizations can exhibit consistent skill for varying degrees of BB influence as long as Nd is known. Lastly, the composition of both droplet residual particles and cloud water changed significantly when clouds were impacted by BB plumes, with differences observed for different fire sources stemming largely from effects of plume aging time and dust influence.

Original languageEnglish (US)
Pages (from-to)12301-12318
Number of pages18
JournalJournal of Geophysical Research: Atmospheres
Volume124
Issue number22
DOIs
StatePublished - Nov 27 2019

Keywords

  • ACTIVATE
  • Aerosol
  • Biomass Burning
  • Cloud
  • EVS-3
  • Stratocumulus

ASJC Scopus subject areas

  • Geophysics
  • Forestry
  • Oceanography
  • Aquatic Science
  • Ecology
  • Water Science and Technology
  • Soil Science
  • Geochemistry and Petrology
  • Earth-Surface Processes
  • Atmospheric Science
  • Earth and Planetary Sciences (miscellaneous)
  • Space and Planetary Science
  • Palaeontology

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    Hossein Mardi, A., Dadashazar, H., MacDonald, A. B., Crosbie, E., Coggon, M. M., Azadi Aghdam, M., Woods, R. K., Jonsson, H. H., Flagan, R. C., Seinfeld, J. H., & Sorooshian, A. (2019). Effects of Biomass Burning on Stratocumulus Droplet Characteristics, Drizzle Rate, and Composition. Journal of Geophysical Research: Atmospheres, 124(22), 12301-12318. https://doi.org/10.1029/2019JD031159