Hygroscopic properties of smoke-generated organic aerosol particles emitted in the marine atmosphere

TitleHygroscopic properties of smoke-generated organic aerosol particles emitted in the marine atmosphere
Publication TypeJournal Article
Year of Publication2013
AuthorsWonaschutz A, Coggon M, Sorooshian A, Modini R, Frossard AA, Ahlm L, Mulmenstadt J, Roberts GC, Russell LM, Dey S., Brechtel F.J, Seinfeld JH
JournalAtmospheric Chemistry and Physics
Date Published2013/10
Type of ArticleArticle
ISBN Number1680-7316
Accession NumberWOS:000325654900009
Keywordsccn activity; critical supersaturation; dash-sp; droplet activation; growth measurements; high-resolution; horizon oil-spill; humidified tdma; mass-spectrometry; water-uptake

During the Eastern Pacific Emitted Aerosol Cloud Experiment (E-PEACE), a plume of organic aerosol was produced by a smoke generator and emitted into the marine atmosphere from aboard the R/V Point Sur. In this study, the hygroscopic properties and the chemical composition of the plume were studied at plume ages between 0 and 4 h in different meteorological conditions. In sunny conditions, the plume particles had very low hygroscopic growth factors (GFs): between 1.05 and 1.09 for 30 nm and between 1.02 and 1.1 for 150 nm dry size at a relative humidity (RH) of 92 %, contrasted by an average marine background GF of 1.6. New particles were produced in large quantities (several 10 000 cm(-3)), which lead to substantially increased cloud condensation nuclei (CCN) concentrations at super-saturations between 0.07 and 0.88 %. Ratios of oxygen to carbon (O : C) and water-soluble organic mass (WSOM) increased with plume age: from <0.001 to 0.2, and from 2.42 to 4.96 mu g m(-3), respectively, while organic mass fractions decreased slightly (similar to 0.97 to similar to 0.94). High-resolution aerosol mass spectrometer (AMS) spectra show that the organic fragment m/z 43 was dominated by C2H3O+ in the small, new particle mode and by C3H7+ in the large particle mode. In the marine background aerosol, GFs for 150 nm particles at 40% RH were found to be enhanced at higher organic mass fractions: an average GF of 1.06 was observed for aerosols with an organic mass fraction of 0.53, and a GF of 1.04 for an organic mass fraction of 0.35.

Short TitleAtmos. Chem. Phys.
Student Publication: