Atmospheric Chemistry and Physics Discussions www.atmos-chem-phys-discuss.net 1680-7367 1680-7375 8 1 2008 10.5194/acpd-8-2381-2008 http://www.atmos-chem-phys-discuss.net/8/2381/2008/ http://www.atmos-chem-phys-discuss.net/8/2381/2008/acpd-8-2381-2008.html http://www.atmos-chem-phys-discuss.net/8/2381/2008/acpd-8-2381-2008.pdf 2381 2401 2008-02-08 Comparison of total ozone and erythemal UV data from OMI with ground-based measurements at Rome station I. Ialongo iolanda.ialongo@uniroma1.it G. R. Casale A. M. Siani Physics Department, Sapienza – University of Rome, Italy Ground-based total ozone and surface UV irradiance measurements have been collected since 1992 using Brewer spectrophotometer and Erythemal Dose Rates (EDRs) have been determined by a broad-band radiometer (model YES UVB-1) operational since 2000 at Rome station. The methodology to retrieve the EDR and the Erythemal Daily Dose (EDD) from the radiometer observations is described. Ground-based measurements were compared with satellite-derived total ozone and UV data from the Ozone Monitoring Instrument (OMI). OMI, onboard the NASA EOS Aura spacecraft, is a nadir viewing spectrometer that provides total ozone and surface UV retrievals. The results of the validation exercise showed satisfactory agreement between OMI and Brewer total ozone data, for both OMI-TOMS and OMI-DOAS ozone alghorithms (biases of −1.8% and −0.7%, respectively). Regarding UV data, OMI data overestimate ground-based erythemally weighted data retrieved from both Brewer and YES Radiometer (biases about 20%), probably because of the effect of absorbing aerosols in an urban site such as Rome. Arola, A., Kazadzis, S., Krotkov, N., Bais, A., Groebner, J., and Herman, J. R.: Assessment of TOMS UV bias due to absorbing aerosols, J. Geophys. Res., 110, D23211, doi:10.1029/2005JD005913, 2005. 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Weihs, P., Simic, S., Buchard, V., Brogniez, C., Chiapello, I., Lenoble, J.: Validation of OMI products over Europe with ground-based UV instruments, OMI Science Team Meeting, 20–22/06/2006, KNMI, De Bilt, The Netherlands, 2006.