SURFACE OZONE AT RURAL SITES IN THE LATROBE VALLEY AND CAPE GRIM, AUSTRALIA

Ozone and other air quality data from five rural sites in the industrialized Latrobe Valley, Victoria, have been subject to statistical analyses including linear regression modeling. The behavior of O//3 in the Latrobe Valley is explained largely in terms of natural background atmospheric processes as observed at Cape Grim, Tasmania. A comparison of observations from an elevated station (750 m) with those from the valley floor shows systematic differences in seasonal and diurnal O//3 variations and the time of day of occurrence of elevated O//3 concentrations which can be explained in terms of the diurnal cycle of convective mixing and mountain/valley winds. A linear regression model incorporating this understanding has accounted for between 43% and 64% of the variance of O//3 concentration at the elevated and rural stations. The standard deviation of the residual O//3 values (observed minus fitted) is around 5 ppb. Auto and cross correlations are used to show that perhaps half of the unexplained variance is coherent from site to site and hence potentially could be modeled.