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Effects of Biomass Burning on Stratocumulus Droplet Characteristics, Drizzle Rate, and Composition
Author(s) -
Hossein Mardi Ali,
Dadashazar Hossein,
MacDonald Alexander B.,
Crosbie Ewan,
Coggon Matthew M.,
Azadi Aghdam Mojtaba,
Woods Roy K.,
Jonsson Haflidi H.,
Flagan Richard C.,
Seinfeld John H.,
Sorooshian Armin
Publication year - 2019
Publication title -
journal of geophysical research: atmospheres
Language(s) - English
Resource type - Journals
eISSN - 2169-8996
pISSN - 2169-897X
DOI - 10.1029/2019jd031159
Subject(s) - drizzle , cloud condensation nuclei , marine stratocumulus , aerosol , atmospheric sciences , environmental science , plume , effective radius , troposphere , cloud top , sulfate , liquid water content , meteorology , chemistry , cloud computing , geography , geology , precipitation , physics , organic chemistry , quantum mechanics , galaxy , computer science , operating system
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 ( N d ) 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 N d 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 N d 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.