Temperature-dependent accumulation mode particle and cloud nuclei concentrations from biogenic sources during WACS 2010

TitleTemperature-dependent accumulation mode particle and cloud nuclei concentrations from biogenic sources during WACS 2010
Publication TypeJournal Article
Year of Publication2013
AuthorsAhlm L, Shakya KM, Russell LM, Schroder JC, Wong JPS, Sjostedt SJ, Hayden KL, Liggio J, Wentzell JJB, Wiebe HA, Mihele C, Leaitch WR, Macdonald M
JournalAtmospheric Chemistry and Physics
Date Published2013/03
Type of ArticleArticle
ISBN Number1680-7316
Accession NumberWOS:000316961000029
Keywordsamazon; atmospheric particles; basin; emissions; functional-groups; isoprene; mass-spectrometer; positive matrix factorization; products; secondary organic aerosol; similarities

Submicron aerosol particles collected simultaneously at the mountain peak (2182 m a.s.l.) and at a forested mid-mountain site (1300 m a.s.l.) on Whistler Mountain, British Columbia, Canada, during June and July 2010 were analyzed by Fourier transform infrared (FTIR) spectroscopy for quantification of organic functional groups. Positive matrix factorization (PMF) was applied to the FTIR spectra. Three PMF factors associated with (1) combustion, (2) biogenics, and (3) vegetative detritus were identified at both sites. The biogenic factor was correlated with both temperature and several volatile organic compounds (VOCs). The combustion factor dominated the submicron particle mass during the beginning of the campaign, when the temperature was lower and advection was from the Vancouver area, but as the temperature started to rise in early July, the biogenic factor came to dominate as a result of increased emissions of biogenic VOCs, and thereby increased formation of secondary organic aerosol (SOA). On average, the biogenic factor represented 69% and 49% of the submicron organic particle mass at Whistler Peak and at the mid-mountain site, respectively. The lower fraction at the mid-mountain site was a result of more vegetative detritus there, and also higher influence from local combustion sources. The biogenic factor was strongly correlated (r similar to 0.9) to number concentration of particles with diameter (D-p) > 100 nm, whereas the combustion factor was better correlated to number concentration of particles with D-p < 100 nm (r similar to 0.4). The number concentration of cloud condensation nuclei (CCN) was correlated (r similar to 0.7) to the biogenic factor for supersaturations (S) of 0.2% or higher, which indicates that particle condensational growth from biogenic vapors was an important factor in controlling the CCN concentration for clouds where S >= 0.2 %. Both the number concentration of particles with D-p > 100 nm and numbers of CCN for S >= 0.2% were correlated to temperature. Considering the biogenic influence, these results indicate that temperature was a primary factor controlling these CCN concentrations at 0.2% supersaturation.

Short TitleAtmos. Chem. Phys.
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