Ozone Monitoring Instrument spectral UV irradiance products: comparison with ground based measurements at an urban environment S. Kazadzis1,2, A. Bais2, A. Arola3, N. Krotkov4, N. Kouremeti2, and C. Meleti2 1Finnish Meteorological Institute, Research and Development, Helsinki, Finland 2Laboratory of Atmospheric Physics, Aristotle University Thessaloniki, Greece 3Finnish Meteorological Institute, Research and Development, Kuopio, Finland 4Goddard Earth Sciences and Technology Center, University of Maryland, Baltimore County, Baltimore, Maryland, USA
Abstract. We have compared spectral ultraviolet overpass irradiances from the Ozone
Monitoring Instruments (OMI) against ground-based Brewer measurements at
Thessaloniki, Greece from September 2004 to December 2007. It is
demonstrated that OMI overestimates UV irradiances by 30%, 17% and
13% for 305 nm, 324 nm, and 380 nm respectively and 20% for erythemally
weighted irradiance. The bias between OMI and Brewer increases with
increasing aerosol absorption optical thickness. We present methodologies
that can be applied for correcting this bias based on experimental results
derived from the comparison period and also theoretical approaches using
radiative transfer model calculations. All correction approaches minimize
the bias and the standard deviation of the ratio OMI versus Brewer ratio.
According to the results, the best correction approach suggests that the OMI
UV product has to be multiplied by a correction factor CA(λ)
of the order of 0.8, 0.88 and 0.9 for 305 nm, 324 nm and 380 nm respectively.
Limitations and possibilities for applying such methodologies in a global
scale are also discussed.
Citation: Kazadzis, S., Bais, A., Arola, A., Krotkov, N., Kouremeti, N., and Meleti, C.: Ozone Monitoring Instrument spectral UV irradiance products: comparison with ground based measurements at an urban environment, Atmos. Chem. Phys., 9, 585-594, doi:10.5194/acp-9-585-2009, 2009.