UVB RADIATION DISTRIBUTION IN CANADA DURING 1992 AND 1993

Abstract

One of the steps leading to an assessment of the biological significance of ozone destruction is to determine the biologically effective ultraviolet radiation (UVB) distribution. The objective of this study is to describe and analyze broadband UVB radiation at 24 locations across Canada, during the period from July 1992 through December 1993. This is the first study of broadband UVB measurements involving such a large number of UVB measuring instruments. Quantitative characteristics and statistical analysis of the surface UVB radiation in Canada with respect to ozone amount, as well as cloudiness, are presented. The results indicate higher UVB irradiance in the second half of 1992, compared with the same period in 1993. Among all the locations, Toronto received the greatest dose of UVB radiation in 1993. Excluding Yellowknife, due to its northernmost location (larger zenith angles), Ste-Agathe, Quebec received the smallest dose. Unusually high UVB fluxes were found to occur in March 1993 over eastern Canada. A study of the correlation of UVB radiation with total ozone and cloud opacity was carried out for most of the locations. The results suggest that other meteorological parameters have a significant impact on the ultraviolet levels.