Real-time UV index retrieval in Europe using Earth observation-based techniques: system description and quality assessment

Abstract. This study introduces an Earth observation (EO)-based system which is capable of operationally estimating and continuously monitoring the ultraviolet index (UVI) in Europe. UVIOS (i.e., UV-Index Operating System) exploits a synergy radiative transfer models with high-performance computing EO data from satellites (Meteosat Second Generation Meteorological Operational Satellite-B) retrieval processes (Tropospheric Emission Monitoring Internet Service, Copernicus Atmosphere Service Global Land Service). It provides near-real-time nowcasting short-term forecasting service for UV radiation over The main atmospheric inputs UVI simulations include ozone, clouds aerosols, while impacts ground elevation surface albedo are also taken into account. output at high spatial temporal resolution (5 km 15 min, respectively) Europe 1.5 million pixels) real time. empirically related to biologically important dose rates, reliability this EO-based solution was verified against ground-based measurements 17 stations across Stations equipped spectral, broadband or multi-filter instruments cover range topographic conditions. A period 1 year forecasted min retrievals under all-sky conditions compared measurements. forecasts were within ±0.5 measured least 70 % all stations. For clear-sky agreement better than 0.5 80 data. sensitivity analysis outputs performed order quantify level uncertainty derived products identify covariance between accuracy quality inputs. Overall, slightly overestimated due observational uncertainties cloud aerosol. will hopefully contribute capabilities assist provision operational early warning systems that help raise awareness among European Union citizens health implications doses.