The relationship between total ozone and spectral UV irradiance from Brewer observations and its use for derivation of total ozone from UV measurements



Spectral UV irradiance measurements made by Brewer spectrophotometers at 7 stations over periods from 4 to 7 years together with Dobson and Brewer direct sun total ozone measurements have been used to establish a statistical relationship between total ozone, solar zenith angle, and UV irradiance. Using the relationship it is possible to estimate daily mean total ozone from routine UV measurements with a standard error of about 3%. Also the spectral irradiance for wavelengths between 300 and 325 nm can be estimated with error of about 25% at 300 nm and lower at longer wavelengths. The relationship is helpful for quality control of UV data. It can also be used to estimate total ozone at sites where spectral UV irradiance is measured and no direct ozone observations are made.