Air quality measurements were taken in Phoenix, Arizona, during June of 2001 as part of the Department of Energy's Atmospheric Chemistry Program studies in the southwestern United States. Previously, we had taken measurements at Usery Pass, northeast of the city of Phoenix, and observed a number of interesting transport-related phenomena (1) at the eastern end of the urban area. Now we report results from a site located at the western boundary of the Phoenix metropolitan area, at an agricultural station operated by the University of Arizona. We will compare results from the two field studies for ozone, peroxyacetyl nitrate, nitrogen dioxide, carbon monoxide, and aerosol measurements. Results from a real-time olefin monitor deployed during the 2001 study will also be presented. These results indicate that both isoprene and monoterpene emissions from the citrus groves in the eastern portion of the city and from natural foliage might be important sources of reactive hydrocarbons.

1. J.S. Gaffney, N.A. Marley, P.J. Drayton, P.V. Doskey, V.R. Kotamarthi, M.M. Cunningham, J.C. Baird, J. Dintaman, and H.L. Hart, "Field Observations of Regional and Urban Impacts on NO2, Ozone, UV-B, and Nitrate Radical Production Rates: Nocturnal Urban Plumes and Regional Smoke Effects." Atmospheric Environment, 36, 825-833 (2002).