Traceable total ozone column retrievals from direct solar spectral irradiance measurements in the ultraviolet

Abstract. Total column ozone (TCO) is commonly measured by Brewer and Dobson spectroradiometers. Both types of instruments use solar irradiance measurements at four wavelengths in the ultraviolet radiation range to derive TCO. For calibration quality assurance TCO both instrument require periodic field comparisons with a reference instrument. This study presents traceable retrievals from direct spectral portable UV QASUME. retrieved fitting technique derived minimal least square fit algorithm using wavelength between 305 345 nm. The retrieval based on an atmospheric model accounting for different parameters such as effective temperature, aerosol optical depth, Rayleigh scattering, SO2, ground air pressure, absorption cross sections top-of-the-atmosphere spectrum. Traceability achieved fully characterizing calibrating QASUME spectroradiometer laboratory SI standards (International System Units). method this independent any does not situ calibration. results show that can be relative standard uncertainty less than 0.8 % when uncertainties model, sections, spectra, temperature or other parameters. long-term comparison Davos, Switzerland, reveals all three are consistent within 1 section University Bremen. From presented here, absolute calibrated cost-effective spectroradiometers, array may applied monitoring.