Submicron aerosol characterization during CARES 2010 field campaign using high-resolution aerosol mass spectrometry at the suburban site
Authors
Timothy B Onasch — Aerodyne Research, Inc.
Rahul Zaveri — Pacific Northwest National Laboratory
Qi Zhang — University of California, Davis
Chen Song — Pacific Northwest National Laboratory
John E Shilling — Pacific Northwest National Laboratory
Category
Aerosol Properties
Description
An Aerodyne High-Resolution Time-of-Flight Aerosol Mass Spectrometer (HR-ToF-AMS) was deployed downstream to a thermodenuder at the campus of American River College, Sacramento, California (the T0 site, a suburban area, ~ 15 km to the northeast of the Sacramento downtown area) during the DOE Carbonaceous Aerosol and Radiative Effects Study (CARES) in June 2010 to investigate the aerosol chemical composition and volatility. Preliminary data analysis from the HR-ToF-AMS shows that the dominant component in the particle phase is organics (62.5%), accompanied by a significant fraction of sulfate (22.0%) and small amounts of nitrate (6.1%) and ammonium (8.6%), while the particle phase chloride is almost negligible (< 1%). The total particle concentration ranged from 0.1 to 11.0 ug/m3 with an average of 2.4 ug/m3 during the whole campaign. A diurnal pattern, with particle mass concentration peaked in the early afternoon, was observed throughout most of the campaign with a few exceptions. In addition, the particle number concentration measured by a TSI Scanning Mobility Particle Sizer (SMPS) shows a similar diurnal pattern to that of particle mass. Fast growth of particles with small sizes was often observed starting in the early or mid-morning, indicating new particle formation that is dominated by both organics and sulfate. Further data analysis including positive matrix factorization (PMF) and chemical speciation based on size distribution and volatility will also be discussed.
