TY - JOUR
T1 - Quantifying the ozone "weekend effect" at various locations in Phoenix, Arizona
AU - Atkinson-Palombo, Carol M.
AU - Miller, James A.
AU - Balling, Robert
N1 - Funding Information:
The authors acknowledge the NSF-IGERT (National Science Foundation Integrative Graduate Evaluation, Research, and Training) in Urban Ecology program at the Global Institute for Sustainability at Arizona State University for their support of this research, in particular for funding Sara Broyles, who created our map. We also thank Sandra Wardwell and Judy Needham at the Arizona Department of Environmental Quality (ADEQ) for their assistance with air pollution data, and Peter Hyde at ADEQ for his help in understanding the regional geography of ozone.
PY - 2006/12
Y1 - 2006/12
N2 - Analysis of pollution data from a network of monitors in Maricopa County, Arizona, reveals considerable variation in the magnitude of the ozone "weekend effect" depending on how and where it is measured. We used four separate methods to calculate the weekend effect, all of which showed that the phenomenon is stronger in the urban core, where ozone is produced. Spatial linear regressions show that the magnitude of the weekend effect and the goodness of fit of weekly harmonic cycles in ozone is a function of urbanization, described quantitatively using an index of traffic counts, population, and employment within a 4 km buffer zone of monitoring sites. Analysis of diurnal patterns of ozone as well as oxides of nitrogen (NOx) at a representative site in the urban core supports the hypothesis that lower levels of NOx on Sundays reduce the degree to which ozone is titrated, resulting in a higher minimum and hence mean for that day of the week (DOW). Fringe sites, where ozone concentrations are higher in absolute terms than in the urban core, show almost no "weekend effect," regardless of which of the four individual methods we used. Alternative quantification methods show statistically significant DOW differences in ozone levels in urban fringe locations, albeit out of phase with the weekly cycling of ozone in the urban core. Our findings suggest that multiple metrics need to be used to test for the weekend effect and that the causes of DOW differences in ozone concentrations may be location specific.
AB - Analysis of pollution data from a network of monitors in Maricopa County, Arizona, reveals considerable variation in the magnitude of the ozone "weekend effect" depending on how and where it is measured. We used four separate methods to calculate the weekend effect, all of which showed that the phenomenon is stronger in the urban core, where ozone is produced. Spatial linear regressions show that the magnitude of the weekend effect and the goodness of fit of weekly harmonic cycles in ozone is a function of urbanization, described quantitatively using an index of traffic counts, population, and employment within a 4 km buffer zone of monitoring sites. Analysis of diurnal patterns of ozone as well as oxides of nitrogen (NOx) at a representative site in the urban core supports the hypothesis that lower levels of NOx on Sundays reduce the degree to which ozone is titrated, resulting in a higher minimum and hence mean for that day of the week (DOW). Fringe sites, where ozone concentrations are higher in absolute terms than in the urban core, show almost no "weekend effect," regardless of which of the four individual methods we used. Alternative quantification methods show statistically significant DOW differences in ozone levels in urban fringe locations, albeit out of phase with the weekly cycling of ozone in the urban core. Our findings suggest that multiple metrics need to be used to test for the weekend effect and that the causes of DOW differences in ozone concentrations may be location specific.
KW - Atmospheric pollution
KW - Harmonic analysis
KW - Ozone precursors
KW - Temporal variation
KW - Weekend/weekday effects
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U2 - 10.1016/j.atmosenv.2006.05.023
DO - 10.1016/j.atmosenv.2006.05.023
M3 - Article
AN - SCOPUS:33750315949
SN - 1352-2310
VL - 40
SP - 7644
EP - 7658
JO - Atmospheric Environment
JF - Atmospheric Environment
IS - 39
ER -