Journal cover Journal topic
Atmospheric Chemistry and Physics An interactive open-access journal of the European Geosciences Union
Journal topic

Journal metrics

Journal metrics

  • IF value: 5.509 IF 5.509
  • IF 5-year value: 5.689 IF 5-year 5.689
  • CiteScore value: 5.44 CiteScore 5.44
  • SNIP value: 1.519 SNIP 1.519
  • SJR value: 3.032 SJR 3.032
  • IPP value: 5.37 IPP 5.37
  • h5-index value: 86 h5-index 86
  • Scimago H index value: 161 Scimago H index 161
Discussion papers | Copyright
© Author(s) 2018. This work is distributed under
the Creative Commons Attribution 4.0 License.

Research article 14 May 2018

Research article | 14 May 2018

Review status
This discussion paper is a preprint. It is a manuscript under review for the journal Atmospheric Chemistry and Physics (ACP).

Assessment of Sun photometer Langley calibration at the high-elevation sites Mauna Loa and Izaña

Carlos Toledano1, Ramiro González1, David Fuertes1,2, Emilio Cuevas3, Thomas F. Eck4,5, Stelios Kazadzis6, Natalia Kouremeti6, Julian Gröbner6, Philippe Goloub7, Luc Blarel7, Roberto Román1, África Barreto8,3,1, Brent N. Holben4, and Victoria E. Cachorro1 Carlos Toledano et al.
  • 1Group of Atmospheric Optics, University of Valladolid (GOA-UVa), Spain
  • 2GRASP-SAS, Lille, France
  • 3Izaña Atmospheric Research Center, Meteorological State Agency of Spain (AEMET), Tenerife, Spain
  • 4NASA Goddard Space Flight Center, Greenbelt, MD, USA
  • 5Universities Space Research Association, Columbia, MD, USA
  • 6Physikalisch-Meteorologisches Observatorium Davos, World Radiation Center – PMOD/WRC, Davos, Switzerland
  • 7Laboratory of Atmospheric Optics, University of Lille, Villeneuve d’Ascq, France
  • 8Cimel Electronique, Paris, France

Abstract. The aim of this paper is to analyze the suitability of the high-mountain stations Mauna Loa and Izaña for Langley plot calibration of Sun photometers. Thus the aerosol optical depth (AOD) characteristics and seasonality, as well as the cloudiness, have been investigated in order to provide a robust estimation of the calibration accuracy, as well as the number of days that are suitable for Langley calibrations. The data used for the investigations belong to AERONET and GAW-PFR networks, which maintain reference Sun photometers at these stations with long measurement records: 22 years at Mauna Loa and 15 years at Izaña. In terms of clear sky and stable aerosol conditions, Mauna Loa (3397m a.s.l.) exhibits on average of 377 Langleys (243 morning and 134 afternoon) per year suitable for Langley plot calibration, whereas Izaña (2373m a.s.l.) shows 343 Langleys (187 morning and 155 afternoon) per year. The background AOD (500nm wavelength) values, on days that are favorable for Langley calibrations, are in the range 0.01–0.02 throughout the year, with well-defined seasonality that exhibits a spring maximum at both stations plus a slight summer increase at Izaña. The statistical analysis of the long-term determination of extraterrestrial signals yields to a calibration uncertainty of ~0.2–0.5%, being this uncertainty smaller in the near infrared and larger in the ultraviolet wavelengths. This is due to atmospheric variability that cannot be reduced based only on quality criteria of individual Langely plots.

Download & links
Carlos Toledano et al.
Interactive discussion
Status: final response (author comments only)
Status: final response (author comments only)
AC: Author comment | RC: Referee comment | SC: Short comment | EC: Editor comment
[Login for Authors/Co-Editors] [Subscribe to comment alert] Printer-friendly Version - Printer-friendly version Supplement - Supplement
Carlos Toledano et al.
Carlos Toledano et al.
Total article views: 292 (including HTML, PDF, and XML)
HTML PDF XML Total Supplement BibTeX EndNote
206 77 9 292 15 8 10
  • HTML: 206
  • PDF: 77
  • XML: 9
  • Total: 292
  • Supplement: 15
  • BibTeX: 8
  • EndNote: 10
Views and downloads (calculated since 14 May 2018)
Cumulative views and downloads (calculated since 14 May 2018)
Viewed (geographical distribution)
Total article views: 292 (including HTML, PDF, and XML) Thereof 291 with geography defined and 1 with unknown origin.
Country # Views %
  • 1
No saved metrics found.
No discussed metrics found.
Latest update: 15 Jul 2018
Publications Copernicus
Short summary
Most of the ground-based radiometric networks have their reference instruments and/or calibrate them at Mauna Loa or Izaña. The suitability of these high-mountain stations for absolute radiometric calibrations is investigated with the support of 20 years of first-class Sun photometer data from the AERONET and GAW-PFR networks. We analyze the number of calibration days at each site in a climatological sense and investigate the accuracy of the calibrations based on long-term statistics.
Most of the ground-based radiometric networks have their reference instruments and/or calibrate...