Examining urban excess in PM2.5 speciated aerosol concentrations with the IMPROVE and CSN networks

Jenny Hand (1), Bret Schichtel (2), William Malm (1), Warren White (3), Lowell Ashbaugh (3), Chuck McDade (3), Marc Pitchford (4)

(1) Cooperative Institute for Research in the Atmosphere, Colorado State University, Fort Collins (2) National Park Service, Air Resource Division, Fort Collins (3) Crocker Nuclear Laboratory, University of California, Davis (4) NOAA, Desert Research Institute, Las Vegas

     Abstract Number: 230
     Last modified: April 30, 2010

Abstract
The rural IMPROVE network (Interagency Monitoring of Protected Visual Environments) and EPA’s urban Chemical Speciation Network (CSN) are two long-term monitoring networks that are responsible for measuring speciated PM2.5 aerosol composition around the United States. The IMPROVE network was initiated in 1988 with the primary objectives of tracking spatial and temporal trends in visibility, and identifying the aerosol species responsible for visibility degradation in protected federal areas. The CSN urban network began in early 2000 with the purpose of identifying sources, developing implementation plans and supporting ongoing health effects research. Although the networks operate independently and for different purposes, both networks monitor the same major aerosol species and therefore data from both networks can be used to investigate the spatial and temporal variability in aerosol concentrations. Specifically, differences in the characteristics of the aerosol species in urban versus remote regions can be explored to determine the degree of urban excess over remote regional background concentrations. We combined data from over 300 sites from both networks to investigate and quantify the urban excess in aerosol concentrations as a function of species and region. This work has implications for understanding the impacts of urban sources and transport into remote regions and their influence on regional background concentrations.