Climatology of Erythemally and Vitamin D Weighted Irradiance at Thessaloniki, Greece, from a NILU-UV Multi-filter Radiometer and a YES UVB-1 Radiometer

A UV monitoring network in Greece was established in 2004, equipped with NILU-UV multi-filter radiometers. It was designed to cover geographically Greece and Cyprus, with nine stations distributed at locations representing different environments. The NILU-UV instrument provides irradiance measurements at five wavelength bands centered at 305, 312, 320, 340 and 380 nm, with full width at half maximum (FWHM) of approximately 10 nm. The irradiance measurements at the five wavelengths are used to derive various products, among them the CIE and the Vitamin D weighted irradiances (dose rates). The measurements are recorded in 1-minute intervals and can provide sufficient details about the daily variation of irradiance.
   One of the UVNET stations is located at Thessaloniki, Greece (40.5º N, 23º E) where a YES UVB-1 radiometer operates regularly. Following appropriate methodologies which depend on the type of the instrument and the available spectral information, the erythemal irradiance and the vitamin D weighted irradiance are calculated from these two instruments.
   One of the aims of this study is to assess the differences of the CIE-weighted irradiance derived from the available instruments. A five-year (2004-2009) dataset of common measurements with NILU-UV and YES UVB-1 radiometer for the station of Thessaloniki is used to calculated the CIE-weighted irradiance and the uncertainties introduced by the different methods are assessed. In addition, the vitamin D weighted irradiances derived from the YES UVB-1 radiometer with two different methodologies are compared with those retrieved from NILU-UV.
   Based on our findings, the risks versus the benefits of the solar UV radiation are discussed for the station of Thessaloniki in Greece.