title: Variation of surface ozone in the ambient air of Auckland, New Zealand.
abstract: A study has been performed on the characteristics and behavior of surface ozone concentrations at four monitoring sites in Auckland, New Zealand (37 degrees S, 174.8 degrees E) for a four-year period (October 1997-October 2001). One monitoring site (rural) was located upwind of the Auckland urban complex, a second downwind (rural-coastal), and a third within the urban area, while the fourth was an elevated urban-city site located 250 m up the Sky Tower in the central city. In contrast to the high elevation site, the diurnal behaviour of ozone at the three low elevation sites followed a typical solar radiation cycle with high ozone during the day and low nocturnal values. The effect of NO(x) titration was distinct at the urban sites. There was also a seasonal variability in the measured ozone levels with high concentrations in spring and a significant summer minimum. The observed surface ozone concentrations in Auckland were significantly lower than other cities of the world, although a potential for high oxidant formation existed. Observed ozone episodes appear to have been either generated locally or the precursors transported via the prevailing southwest wind. A unique feature of Auckland's air quality is the dilution of polluted city air due to the mixing of east-coast air into the clean west-coast circulation leading to the overall lower average concentrations in summer. A second feature is the potential interaction between sea salt particles and ozone that may provide an additional ozone loss mechanism.
authors.affiliation: School of Geography and Environmental Science, Tamaki Campus, The University of Auckland, Auckland, New Zealand.
authors.forename: Farah
authors.initials: F
authors.lastname: Adeeb
authors.forename: David
authors.initials: D
authors.lastname: Shooter
mesh_terms: D000393:Air Pollutants / Q000032:analysis*; D004784:Environmental Monitoring; D009520:New Zealand; D010126:Ozone / Q000032:analysis*; D012424:Rural Population; D012621:Seasons; D017186:Titrimetry
chemical_list: D000393:Air Pollutants; D010126:Ozone