Abstract

Atmospheric variables that affect ground reaching UV-B irradiance include ozone, solar zenith angle, earth–sun distance, clouds, aerosols, etc. It is a known fact that total column ozone and ground reaching UV-B irradiance are inversely related. The aim of this paper is to estimate the variation of the biologically effective UV-B irradiance with variation in ozone at a coastal urban location, Visakhapatnam for the period, January 2010 to December 2010. A regression model that was developed with measurements made by a UV-B photometer operated at Visakhapatnam in 1990 (Krishna and Niranjan, 2005) is now reused to estimate the incoming UV-B irradiance by inputting TOMS ozone for the year 2010. An attempt was made to compare both measurements which are reported in this paper. For the analyzed period (January 2010 to December, 2010), variation of estimated UV-B irradiance with ozone for different wavelengths is found for different solar zenith angles. To assess the biological effects of incoming UV-B irradiance, erythemal irradiance was estimated and its variation with ozone as a function of wavelength and solar zenith angle was reported. These results indicate the efficiency of the regression model developed for this station.

Key words: UV-B irradiance, regression, ozone.