Source characteristics and mixing state of black carbon during CARES 2010
Authors
Greg Kok — Droplet Measurement Technologies
Arthur J Sedlacek — Brookhaven National Laboratory
Rahul Zaveri — Pacific Northwest National Laboratory
R. Subramanian — Carnegie Mellon University
Darrel Baumgardner — Droplet Measurement Technologies
Category
Field Campaigns
Description
BC mass concentration and BC mass-equivalent diameter distributions recorded at T0 during a high-BC event.
During the recent Carbonaceous Aerosols and Radiative Effects Study (2010) in California, two single- particle soot photometers (SP2s) were run in parallel at the T0 and T1 sites in Sacramento and Cool, respectively. The SP2 uses laser-induced incandescence (LII) to detect black carbon mass, while scattering is used to determine the mixing state of individual BC-containing particles. At the T0 site near downtown Sacramento, BC concentrations higher than 1 µg/m3 were measured at times, and BC particles tended to be thinly coated. This suggests that the T0 site was impacted by fresh emissions, as expected for an urban area. Two high-BC-mass events were recorded in the early morning hours of June 13 and June 17, but the BC mass-size distributions were different for these two events. The first appears to be biomass smoke, while the second is more indicative of fresh vehicular exhaust. On June 15, the urban plume was forecast to be transported to T1. A closer look at the SP2 results show that though both sites were dominated by thinly coated BC cores, T1 appears to show more thickly coated, sub-100 nm MED BC cores. The mass-mean BC MED at was 143 nm at T0, and 175 nm at T1.
