02 Oct 2019

02 Oct 2019

Review status: this preprint is currently under review for the journal AMT.

Aerosol optical characteristics in the urban area of Rome, Italy, and their impact on the UV index

Monica Campanelli1, Anna Maria Siani2, Alcide di Sarra3, Anna Maria Iannarelli4, Paolo Sanò1, Henri Diémoz5, Giampietro Casasanta1, Marco Cacciani2, Luca Tofful6, and Stefano Dietrich2 Monica Campanelli et al.
  • 1Institute of Atmospheric Sciences and Climate, National Research Council, Rome, Italy
  • 2Sapienza University of Rome, Department of Physics, Rome, Italy
  • 3Dipartimento Ambiente, Cambiamenti Globali e Sviluppo Sostenibile, Ente per le Nuove Tecnologie, l’Energia e l’Ambiente, Rome, Italy
  • 4SERCO, Italy
  • 5Agenzia Regionale Protezione Ambientale-Valle d’Aosta, ARPA-VDA, Italy
  • 6Institute of Atmospheric pollution, National Research Council, Italy

Abstract. The aerosol optical characteristics in the urban area of Rome were retrieved over a period of 7 years from March to September 2010–2016. The impact of aerosol single scattering albedo (SSA), optical depth (AOD), estimated at 400 nm, and Ångström exponent on the ultraviolet (UV) index has been analyzed. Aerosol optical properties are provided by a PREDE-POM sun-sky radiometer of the ESR/SKYNET network and the UV index values were retrieved by a Brewer spectrophotometer both located in Rome. Chemical characterization of urban PM10 (particulate matter 10 micrometers or less in diameter) samples, collected during the URBan Sustainability Related to Observed and Monitored Aerosol (URBS ROMA) intensive filed campaign held in summer 2011 in the same site, was performed. PM macro-components were grouped in order to evaluate the contribution of the main macro-sources (SOIL, SEA, SECONDARY INORGANIC, ORGANICS and TRAFFIC) and the analysis of the modulation of their concentration was found to strongly affects the absorption capability of the atmosphere over Rome. The surface forcing efficiency, provided by the decreasing trend of UV index with AOD, which is the primary parameter affecting the surface irradiance, was found very significant, probably masking the dependence of UV index on SSA and Ångström exponents. Moreover it was found greater for larger particles and with a more pronounced slope at the smaller solar zenith angle. In Rome large particles are generally less absorbing since related to the presence of SOIL and SEA components in the atmosphere. The former contribution was found much higher in summer months because of the numerous episodes of Saharan dust transport.

Monica Campanelli et al.

Status: final response (author comments only)
Status: final response (author comments only)
AC: Author comment | RC: Referee comment | SC: Short comment | EC: Editor comment

Monica Campanelli et al.

Monica Campanelli et al.


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Short summary
The aerosol optical characteristics in the urban area of Rome were retrieved over a period of 7 years from March to September 2010–2016 to determine, for the first time, their effect on the incoming ultraviolet (UV) solar radiation. The increasing of atmospheric turbidity together with the presence of large particles, generally less absorbing since related to sea salt and desert dust components, provided a very significant decreasing trend of UV solar radiation.