THE RELATIONSHIP BETWEEN SOLAR UV IRRADIANCE AND TOTAL OZONE FROM OBSERVATIONS OVER SOUTHERN ARGENTINA

Solar ultraviolet (UV) radiation at 300 and 305 nm, measured by a Biospherical Instruments high resolution scanning spectroradiometer at Ushuaia, southern Argentina (55 degrees S, 68 degrees W), as a part of the US National Science Foundation Network for Polar Regions, was compared with total ozone satellite measurements. A statistical relationship between UV and total ozone was derived. On the basis of this relationship, the differences in 300 and 305 nm irradiance between 1979-1983 and 1989-1993 intervals are estimated; for October, the 15% observed decline of total ozone has led to irradiance increases of 80% at 300 nm and 35% at 305 nm. During the days with ''ozone hole'' conditions, the 300 nm irradiance is as high as it would be at the summer solstice three months later, and is similar to 4 times higher than the UV irradiance corresponding to the ''normal'' ozone condition for early October, as further illustrated for October 1994. Inclusion of the 340 nm cloudy-dependent predictor is discussed.