Aerosol Layering in the Free Troposphere over the Industrial City of Raciborz in Southwest Poland and Its Influence on Surface UV Radiation

Atmospheric aerosol and ultraviolet index (UVI) measurements performed in Racibórz (50.08° N, 18.19° E) were analyzed for the period June–September 2019. Results of following observations taken into account: columnar characteristics aerosols (aerosol thickness, Angstrom exponent, single scattering albedo, asymmetry factor) obtained from standard CIMEL sun-photometer parameters layers (ALs) free troposphere (the number altitudes base top) derived continuous monitoring by a CHM-15k ceilometer. Three categories ALs defined: residues daily evolution planetary boundary layer (PBL) aerosols, PBL-adjacent layer, elevated above PBL. Total column ozone Ozone-Monitoring Instrument on board NASA’s Aura satellite completed list variables used to model UVI variability under clear-sky conditions. The aim was present hybrid (radiative transfer combined with regression model) determining ALs’ impact observed series. First, radiative model, Tropospheric Ultraviolet–Visible (TUV) which uses typical describe UV attenuation atmosphere, applied calculate hypothetical surface values These modeled normalize measured data during cloudless Next, normalized made using AL characteristics. Random forest (RF) chosen search an signal data. This explained about 55% variance series Finally, calculated as product RF relevant UVIs TUV model. root mean square error absolute 1.86% 1.25%, respectively, 1 percentage point lower than corresponding 5th–95th percentile ranges observation/model differences [−2.5%, 2.8%] [−3.0%, 5.3%] respectively. Therefore, radiation could be demonstrated proposed statistical analysis between models allowed us identify specific configuration responsible these differences.