Monitoring of erythemal irradiance in the Argentine ultraviolet network

Abstract

The Ultraviolet (UV) Monitoring Network of the Argentine Servicio Meteorológico Nacional (National Weather Service) consists at present of nine stations from 22° to 64° latitude south equipped with biometers, broadband instruments that measure the erythemal irradiance. After a complete calibration of the instruments and reprocessing of the database a preliminary climatology of erythemal irradiance and erythemal exposure was built by analyzing the data of the first 2-4 years for each station. The influence of the measurement interval on the UV Index is quantified. A tropical high-altitude station in the Andean Altiplano reaches top UV Index values of 20 and daily doses of 10.6 kJ/m2, among the highest UV levels worldwide. Characteristic UV Index and erythemal exposure in the central, most populated areas of Argentina are similar to those in other Southern Hemisphere stations and are higher than in comparable latitude regions of the Northern Hemisphere. The southern stations in the UV network are often affected by the Antarctic ozone hole. By comparing clear-sky irradiance measurements with aerosol-free radiative transfer calculations using the Total Ozone Mapping Spectrometer surface albedo climatology, typical attenuations from 2 to 15% due to aerosols were determined, reaching maxima of 30% at urban locations. On the other hand, increases of ∼3-6% due to higher surface albedo were obtained for snow-free conditions, and increases up to 15% were obtained for snow-covered terrain. Copyright 2002 by the American Geophysical Union.