AAAR 34th Annual Conference
October 12 - October 16, 2015
Hyatt Regency
Minneapolis, Minnesota, USA
Abstract View
Particle Number Concentrations at a Traffic Impacted Site: Precision and Temporal Patterns
Oliver Rattigan, H. Dirk Felton, James Schwab, ROBERT ANDERSON, New York State Dept. of Environmental Conservation
Abstract Number: 306 Working Group: Urban Aerosols
Abstract Concern over increased exposure has been a driving force in requiring air pollutants be measured at near road locations for large urban centers. Here we interpret ambient measurements of pollutants including particle number concentration and black carbon from a traffic impacted site in western New York. A matched pair of water based particle counters, model 651 and a black carbon, model 633 (Teledyne API) were operated on a 1 min sample time. The black carbon provides data at seven wavelengths with auto correction for spot loading. Collocated precision of particle number data (ranging from 10E3-10E5 counts/cm3) was within 10%. Instrument data is used in the analysis of temporal patterns versus auto and truck counts and meteorological parameters on a seasonal basis.
Both particle number and black carbon show a high temporal variability with higher concentrations on weekdays versus weekends. Weekday black carbon generally shows an early morning peak between 6 and 9 AM which is absent on weekends. Particle number also shows a weekday morning peak coincident with the black carbon peak, but a larger and broader particle number peak is observed from noon into the afternoon. Particle number appears better correlated with truck traffic counts than is black carbon, perhaps indicating particle emissions from diesel particulate filters (metals or sulfur based species) could be important. In addition nucleation of semi-volatile emissions external to the vehicle is also possible. The extent of how these temporal patterns vary across seasons will be examined.