Solar UV dose patterns in Italy

Since 1992 solar ultraviolet (UV) spectral irradiance (290-325 nm) has been measured at two Italian stations of Rome (urban site) and Ispra (semirural site) using Brewer spectrophotometry. The data collected under all sky con ditions, are compared with the output of a sophisticated radiative transfer model (System for Transfer of Atmospheric Radiation-STAR model). The STAR multiple scattering scheme is able to cope with all physical processes rele vant to the UV transfer through the atmosphere. The experience so far acqui red indicates that, in spite of the unavoidable uncertainties in the input parameters (ozone, aerosol, surface albedo, pressure, temperature, relative humidity, cloud cover), measured and computed clear sky irradiances are in reasonable agreement. The STAR model is applied to build up the solar UV g eographic patterns in Italy: the daily dose in the range 290-325 nm is comp uted at about 70 sites where a thorough and homogeneous climatology is avai lable, For each month the concept of an idealized "standard day" is introdu ced and the surface distribution of solar UV field determined. The map of s olar UV patterns for Italy, available for the first time, meets the study r equirements in the field of skin and eye epidemiology, as well as in other investigations dealing with the impact of UV on the biosphere. The results are interpreted in terms of atmospheric and meteorological parameters modul ating UV radiation reaching the ground.