UV climatology from quality controlled ground-based spectral UV measurements

Solar spectral UV-monitoring data for 8 European sites with 5-10 years of data, and covering a latitudinal range from 41 degrees North to 67 North have been re-evaluated and resubmitted to the European UV-database (EUVDB) in Finland as part of the EU-project SCOUT-O3. All resubmitted spectra (420000) were quality checked, flagged, and corrected with respect to wavelength scale errors and spectral distortions using the SHICrivm software package. Additional data products provided by the software are standardized spectra, spectral atmospheric transmissions, and biologically weighted UV-irradiances for a wide variety of biological action spectra. The resubmitted spectra were shown to have improved based on the EUVDB quality flagging criteria. Spectral and effective irradiances were integrated and summed in a standardized way to obtain daily, monthly, and seasonal UV-doses. The measured summer sums varies from 478 kJ/m2 for Thessaloniki to 228 kJ/m2 for Sodankyla. Clouds reduced the exposure during summer time by 30% on average, in Bilthoven this was 35%, while in Thessaloniki only 17% was reduced. Using co-located ozone and pyranometer measurements results of a generic UV-modelling approach, derived in a specific low albedo and low surface elevation environment, are systematically compared to the UV-doses obtained for all sites. Generally, a good agreement is found, measured and modelled total UV-doses agree within a few percent with a standard deviation of 15 typically. Deviations with respect to the application in a high surface albedo and high altitude environment have been identified and handles to improve the modelling have been assigned.