MULTIVARIATE-ANALYSIS OF A 1992 SONTOS DATA SUBSET

Statistical analysis of observations made between 7 and 31 August 1992 at a rural site in Southern Ontario, Canada, is presented using princ ipal component analysis (PCA), as well as rank and partial correlation analyses. Data for ozone, CO, SO2, NO, NOy (NO + NO2 including NOx, P AN and HNO3), ethane, ethylene, propane, acetylene and isoprene are em ployed, as well. as such meteorological information as temperature, re lative humidity, wind speed and direction. The analysis involved sever al scenarios classifying the data according to daytime, nighttime and wind direction. A normal correlation analysis suggests that isoprene m ight be important in the build-up of ozone in the S-W sector, whereas it is not important in the N-E wind sector. PCA show that the chemical and the meteorological variables interact differently within the diff erent scenarios. Finally, the relationships between ozone and isoprene for both wind sectors are found to be the same when the data are subj ected to a partial correlation analysis including the meteorological p arameters and it is concluded that the S-W ozone-isoprene relationship might be biased by temperature. Copyright (C) 1996 Elsevier Science L td