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Published November 27, 2019 | Supplemental Material + Published
Journal Article Open

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


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.

Additional Information

© 2019 American Geophysical Union. Received 12 JUN 2019; Accepted 29 OCT 2019; Accepted article online 7 NOV 2019; Published online 28 NOV 2019. All data used in this work can be found on the Figshare database (Sorooshian et al., 2018; https://figshare.com/articles/A_Multi‐Year_Data_Set_on_Aerosol‐Cloud‐Precipitation‐Meteorology_Interactions_for_Marine_Stratocumulus_Clouds/5099983). This work was funded by Office of Naval Research grants N00014‐10‐1‐0811, N00014‐11‐1‐0783, N00014‐10‐1‐0200, N00014‐04‐1‐0118, and N00014‐16‐1‐2567. This work was also partially supported by NASA grant 80NSSC19K0442 in support of the ACTIVATE Earth Venture Suborbital‐3 (EVS‐3) investigation, which is funded by NASA's Earth Science Division and managed through the Earth System Science Pathfinder Program Office.

Attached Files

Published - Mardi_et_al-2019-Journal_of_Geophysical_Research__Atmospheres.pdf

Supplemental Material - jgrd55864-sup-0001-2019jd031159-si.docx


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