AAAR 34th Annual Conference
October 12 - October 16, 2015
Hyatt Regency
Minneapolis, Minnesota, USA
Abstract View
Analysis of Particle Number Concentrations in Houston
CARLOS HERNANDEZ, Yu Jun Leong, Robert Griffin, Rice University
Abstract Number: 112 Working Group: Urban Aerosols
Abstract In many urban areas, high concentrations of aerosols, especially those within the ultrafine region (<100 nm), present a significant risk to human respiratory health. To better understand the number of ultrafine aerosol particles in the Houston atmosphere, a butanol-based condensation particle counter was deployed to measure particle number concentrations (PNC) over a one-year time span during 2012 and 2013. The study first considers a statistical evaluation of this dataset. During the sampling period, PNCs averaged 11,000 ± 7,700 cm$^(-3), with higher concentrations coinciding with peak motor vehicle traffic during weekday mornings and afternoons. We then evaluate the sources of the PNCs via two methods. The first method utilizes principal component analysis (PCA) to develop source profiles for the measured PNC. In order to account for variations in the PNC source profile, the dataset was segregated by season and time of day. Preliminary PCA results indicate motor vehicle traffic and photochemical activity as significant sources. The second method involves a cluster analysis of daily backward trajectories generated using the Hybrid Single Particle Lagrangian Integrated Trajectory (HYSPLIT) model. In order to identify the regional emission sources and meteorological patterns that lead to high ultrafine aerosol concentrations, each backward trajectory developed corresponds to what has been defined as an extreme PNC event (value in excess of the 90th percentile). Preliminary results indicate that airmass transport from the Gulf of Mexico and Northeast Texas is related to increases in PNC.