Phytoplankton blooms weakly influence the cloud forming ability of sea spray aerosol

TitlePhytoplankton blooms weakly influence the cloud forming ability of sea spray aerosol
Publication TypeJournal Article
Year of Publication2016
AuthorsCollins DB, Bertram TH, Sultana C.M, Lee C., Axson J.L, Prather KA
JournalGeophysical Research Letters
Date Published2016/09
Type of ArticleArticle
ISBN Number0094-8276
Accession NumberWOS:000385392900074
Keywordschemical-composition; condensation; global distribution; growth; hygroscopic; microbial loop; mixing state; nucleus activity; oceanic; organic-matter enrichment; phytoplankton; primary marine aerosol; single-parameter representation

After many field studies, the establishment of connections between marine microbiological processes, sea spray aerosol (SSA) composition, and cloud condensation nuclei (CCN) has remained an elusive challenge. In this study, we induced algae blooms to probe how complex changes in seawater composition impact the ability of nascent SSA to act as CCN, quantified by using the apparent hygroscopicity parameter (kappa(app)). Throughout all blooms, kappa(app) ranged between 0.7 and 1.4 (average 0.95 +/- 0.15), consistent with laboratory investigations using algae-produced organic matter, but differing from climate model parameterizations and in situ SSA generation studies. The size distribution of nascent SSA dictates that changes in kappa(app) associated with biological processing induce less than 3% change in expected CCN concentrations for typical marine cloud supersaturations. The insignificant effect of hygroscopicity on CCN concentrations suggests that the SSA production flux and/or secondary aerosol chemistry may be more important factors linking ocean biogeochemistry and marine clouds.

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