An improved algorithm for the determination of aerosol optical depth in the ultraviolet spectral range from Brewer spectrophotometer observations

P. Sellitto, A. Di Sarra, A.M. Siani

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16 Citations (Scopus)


Methods to derive aerosol optical depth in the UV spectral range from ground-based remote-sensing stations equipped with Brewer spectrophotometers have been recently developed. In this study a modified Langley plot method has been implemented to retrieve aerosol optical depth from direct sun Brewer measurements. The method uses measurements over an extended range of atmospheric airmasses obtained with two different neutral density filters, and accounts for short-term variations of total ozone, derived from the same direct sun observations. The improved algorithm has been applied to data collected with a Brewer mark IV, operational in Rome, Italy, and with a Brewer mark III, operational in Lampedusa, Italy, in the Mediterranean. The efficiency of the improved algorithm has been tested comparing the number of determinations of the extraterrestrial constant against those obtained with a standard Langley plot procedure. The improved method produces a larger number of reliable Langley plots, allowing for a better statistical characterization of the extraterrestrial constant and a better study of its temporal variability. The values of aerosol optical depth calculated in Rome and Lampedusa compare well with simultaneous determinations in the 416-440nm interval derived from MFRSR and CIMEL measurements. © 2006 IOP Publishing Ltd.
Original languageEnglish
Article number005
Pages (from-to)849 - 855
Number of pages7
JournalJournal of Optics A: Pure and Applied Optics
Issue number10
Publication statusPublished - 1 Oct 2006
Externally publishedYes


All Science Journal Classification (ASJC) codes

  • Atomic and Molecular Physics, and Optics

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