North American background ozone concentration in surface air for spring and summer 2006. The North American background ozone is defined by the US EPA as the surface ozone concentration that would be present over the US in the absence of North American anthropogenic emissions. It provides a baseline for setting the National Ambient Air Quality Standard (NAAQS). In this work we present three-year GEOS-Chem model statistics of background ozone over the US. We find that the North American background is elevated by 9-13 ppb above the natural background due to Intercontinental pollution and anthropogenic methane. It is particularly high in the intermountain West due to high elevation, arid terrain, and large-scale subsidence. A NAAQS of 60-70 ppb could not be attained in that region through domestic-only emission controls.

Group Secretary:

Brenda Mathieu (blm@as.harvard.edu)

Address:

Pierce Hall, 29 Oxford St.
Harvard University
Cambridge MA 02138-2901, USA
(Directions)

Phone (Brenda Mathieu) 1-617-496-5745
Fax: 1-617-495-4551