Deriving erythemal UV dose rate from Meteosat Observations

Downwelling solar irradiance at the surface is retrieved from the geostationary Meteosat SEVIRI instrument using the SICCS algorithm. The existing SICCS broad-band irradiance product is being extended with irradiance in 5 separate wavelength bands, including two in the ultraviolet (UV). In this study, the first band (283 - 328 nm) has been validated using various Brewer measurements across Europe using data from January and July of 2014. Next, it is investigated whether the improved spectral irradiance information allows estimating the erythemal UV dose rate (UVDr). The UVDr is computed from the Brewer measurements and compared to various SICCS output parameters and cloud physical properties in order to construct a fit to compute the UVDr. The best UVDr model results from fitting clear sky SICCS band 1 irradiance to the ground-based UVDr, to which a cloud correction is applied that is based on cloud optical thickness.