Evaluation of on-site calibration procedures for SKYNET Prede POM sun–sky photometers

Abstract. To retrieve columnar intensive aerosol properties from sun–sky photometers, both irradiance and radiance calibration factors are needed. For the irradiance the solar calibration constant, V0, which denotes the instrument counts for a direct normal solar flux extrapolated to the top of the atmosphere, must be determined. The solid view angle, SVA, is a measure of the field of view of the instrument, and it is important for obtaining the radiance from sky diffuse irradiance measurements. Each of the three sun-photometer networks considered in the present study (SKYNET, AERONET, WMO GAW) adopts different protocols of calibration, and we evaluate the performance of the on-site calibration procedures, applicable to every kind of sun–sky photometer but tested in this analysis only on SKYNET Prede POM01 instruments, during intercomparison campaigns and laboratory calibrations held in the framework of the Metrology for Aerosol Optical Properties (MAPP) European Metrology Programme for Innovation and Research (EMPIR) project. The on-site calibration, performed as frequently as possible (ideally monthly) to monitor changes in the device conditions, allows operators to track and evaluate the calibration status on a continuous basis, considerably reducing the data gaps incurred by the periodic shipments for performing centralized calibrations. The performance of the on-site calibration procedures for V0 was very good at sites with low turbidity, showing agreement with a reference calibration between 0.5 % and 1.5 % depending on wavelengths. In the urban area, the agreement decreases between 1.7 % and 2.5 %. For the SVA the difference varied from a minimum of 0.03 % to a maximum of 3.46 %.

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Publication Details

Journal
Atmospheric measurement techniques
Published
2024-09-03
DOI
https://doi.org/10.5194/amt-17-5029-2024
Citations
2
Primary Topic
Atmospheric aerosols and clouds
Type
article
Field-Weighted Citation Impact
0.57

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article

Evaluation of on-site calibration procedures for SKYNET Prede POM sun–sky photometers

Stefano Casadio, Kerstin Schwind, Monica Campanelli, Henri Diémoz et al.
2 citations
Atmospheric measurement techniques
Atmospheric aerosols and clouds
0.57
article

Evaluation of on-site calibration procedures for SKYNET Prede POM sun–sky photometers

Stefano Casadio, Kerstin Schwind, Monica Campanelli, Henri Diémoz, Anna Maria Iannarelli, Akihiro Yamazaki, Rei Kudo, Gabriele Mevi, Natalia Kouremeti, Saulius Nevas, Víctor Estellés, Gaurav Kumar, Jülian Gröbner, Annalisa Di Bernardino, Petri Kärhä, África Barreto, Akihiro Uchiyama, Angelos Karanikolas, Masahiro Momoi, Teruyuki Nakajima, Stelios Kazadzis, Iiro Harju, Philipp Schneider
article en
2 citations

Abstract

Abstract. To retrieve columnar intensive aerosol properties from sun–sky photometers, both irradiance and radiance calibration factors are needed. For the irradiance the solar calibration constant, V0, which denotes the instrument counts for a direct normal solar flux extrapolated to the top of the atmosphere, must be determined. The solid view angle, SVA, is a measure of the field of view of the instrument, and it is important for obtaining the radiance from sky diffuse irradiance measurements. Each of the three sun-photometer networks considered in the present study (SKYNET, AERONET, WMO GAW) adopts different protocols of calibration, and we evaluate the performance of the on-site calibration procedures, applicable to every kind of sun–sky photometer but tested in this analysis only on SKYNET Prede POM01 instruments, during intercomparison campaigns and laboratory calibrations held in the framework of the Metrology for Aerosol Optical Properties (MAPP) European Metrology Programme for Innovation and Research (EMPIR) project. The on-site calibration, performed as frequently as possible (ideally monthly) to monitor changes in the device conditions, allows operators to track and evaluate the calibration status on a continuous basis, considerably reducing the data gaps incurred by the periodic shipments for performing centralized calibrations. The performance of the on-site calibration procedures for V0 was very good at sites with low turbidity, showing agreement with a reference calibration between 0.5 % and 1.5 % depending on wavelengths. In the urban area, the agreement decreases between 1.7 % and 2.5 %. For the SVA the difference varied from a minimum of 0.03 % to a maximum of 3.46 %.

Atmospheric measurement techniquesVol. 17(17)
Agencia Estatal de Meteorología (ES), Physikalisch-Technische Bundesanstalt (DE), Universitat de València (ES), National Institute for Environmental Studies (JP), Serco (United Kingdom) (GB), Japan Meteorological Agency (JP), Institute of Atmospheric Sciences and Climate (IT), Laboratoire d'Optique Atmosphérique (FR), Physikalisch-Meteorologisches Observatorium Davos (CH), Osservatorio Astronomico della Regione Autonoma Valle d'Aosta (IT), Meteorological Research Institute (JP), Sapienza University of Rome (IT), Aalto University (FI)
European Commission, European Cooperation in Science and Technology, Ministerio de Economía y Competitividad, Staatssekretariat für Bildung, Forschung und Innovation, European Regional Development Fund, European Metrology Programme for Innovation and Research
Industry, innovation and infrastructure, Sustainable cities and communities
Openalex Percentile: Top 34%
Atmospheric aerosols and clouds
0.57
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