Results of a CCPR intercomparison of spectral irradiance measurements by national laboratories

Walker, James H.; Saunders, Robert D.; Jackson, John K.; Mielenz, Klaus D.

doi:10.6028/jres.096.043

Cited by 46 publications

(25 citation statements)

References 4 publications

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“…At the wavelength band 280-400 nm the differences were between -4% and +4%. It seems that the agreement between national standard laboratories has not improved since the previous intercomparison [Walker et al, 1991]. The differences in the lamp intercomparisons of many primary standard laboratories are not radically smaller than the differences observed between the standard lamps of many solar UV monitoring laboratories, which typically vary within +3% Bais, 1998].…”

Section: Radiometric Of the Cornitc International Des Poids Etmentioning

confidence: 99%

Intercomparison of lamp and detector‐based UV‐irradiance scales for solar UV radiometry

Jokela¹,

Ylianttila²,

Visuri³

et al. 2000

J. Geophys. Res.

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Abstract. The high uncertainty of calibration is the most serious factor limiting accurate measurements of the solar UV, needed for the assessment of global UV trends. In this study, the calibration of FEL-type standard lamps traceable to three primary standard laboratories were compared with a transfer uncertainty of _+ 1.4% (2o-). In comparison with the reference lamp, the spectral UV irradiance scales agreed within 1.5%. However, the difference between a new lamp and the present reference was 2%, which is close to the limits of total uncertainty. It was interesting to observe that one of the scales, based on a cryogenic absolute radiometer, was in good agreement with the scales based on blackbody radiation sources. , Examination of the long-term stability of the lamp-based UV scale in Finland showed a significant decrease of 6% in the scale when the standard lamp was changed to a lamp directly traceable to the primary standard of the National Institute of Standards and Technology (NIST). Previously, the lamp was traceable to the NIST through the secondary standard of Optronic Laboratories Inc. The main obstacle in improving the global conformity of UV scales is the instability of halogen standard lamps. On the basis of the present study, it is strongly recommended to use detector stabilization of the standard lamps and to investigate the use of portable detector standards in the intercomparisons between primary standards laboratories. IntroductionThe increase of terrestrial UV at short wavelengths is associated with the decrease in stratospheric ozone. According to theoretical estimates, the increase in biologically effective UV during the last 20 years varies from a few percent at the equator to about 12% at high northern latitudes . Verifying the trends through measurements, however, is difficult because the accuracy of most solar UV measurements is not sufficient [Weatherhead et at., 1998]. For the best spectroradiometric systems the differences may be within _+5% [Gardiner and Kirsch, 1998], but differences up to ___20% are not uncommon. The accuracy problems are due to instrumental deficiencies, inadequate quality assurance of operators, and the uncertainty of calibration.Among the many instrumental error sources the most significant are the deviation of the angular response from the ideal cosine response (___2%), the nonideal slit function (_+1%), the instability of the wavelength scale (_+3%), and the calibration uncertainty (___2%). Calibration Chains for Solar UV RadiometersThe commonly used methodology for the calibration of UV spectroradiometers is based on tungsten-halogen standard lamps calibrated by primary standards laboratories against 4821

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Section: Radiometric Of the Cornitc International Des Poids Etmentioning

confidence: 99%

Intercomparison of lamp and detector‐based UV‐irradiance scales for solar UV radiometry

Jokela¹,

Ylianttila²,

Visuri³

et al. 2000

J. Geophys. Res.

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“…Results of an intercomparison of spectral irradiance from national laboratories gave results of 2 -4% in the ultraviolet region. [30]. More recent studies of reference standards from European solar-ultraviolet laboratories gave differences of as much as 9% with an average difference of less than 3% [31].…”

Section: Solar Irradiance With Participants' Calibration and Cucf Calmentioning

confidence: 95%

2003 North American interagency intercomparison of ultraviolet spectroradiometers: scanning and spectrograph instruments.

Lantz

2008

J. Appl. Remote Sens

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Abstract. The fifth North American Intercomparison of Ultraviolet MonitoringSpectroradiometers was held June 13 to 21, 2003 at Table Mountain outside of Boulder, Colorado, USA. The main purpose of the Intercomparison was to assess the ability of spectroradiometers to accurately measure solar ultraviolet irradiance, and to compare the results between instruments of different monitoring networks. This Intercomparison was coordinated by NOAA and included participants from six national and international agencies. The UV measuring instruments included scanning spectroradiometers, spectrographs, and multi-filter radiometers. Synchronized spectral scans of the solar irradiance were performed between June 16 and 20, 2003. The spectral responsivities were determined for each instrument using the participants' lamps and calibration procedures and with NOAA/CUCF standard lamps. This paper covers the scanning spectroradiometers and the one spectrograph. The solar irradiance measurements from the different instruments were deconvolved using a high resolution extraterrestrial solar irradiance and reconvolved with a 1-nm triangular bandpass to account for differences in the bandwidths of the instruments. The measured solar irradiance from the spectroradiometers using the rivmSHIC algorithm on a clear-sky day on DOY 172 at 17.0 UTC (SZA = 30°) had a relative 1-σ standard deviation of +/-2.6 to 3.4% for 300-to 360-nm using the participants' calibration.

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“…NMIs in other countries include the National Institute of Standards and Technology (U.S.A.), the Laboratoire National de Métrologie et d'Essais (France) and the Physikalisch‐Technische Bundesanstalt (Germany). An intercomparison of spectral irradiance measurements by 12 NMIs in 1991 found the SD was about 2% in the UV region, demonstrating the high level of measurement accuracy and consistency that these laboratories can achieve …”

Section: Ultraviolet Radiometer Calibration Certificatesmentioning

confidence: 98%

Guidelines on the measurement of ultraviolet radiation levels in ultraviolet phototherapy: report issued by the British Association of Dermatologists and British Photodermatology Group 2015

et al. 2015

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Results of a CCPR intercomparison of spectral irradiance measurements by national laboratories

Cited by 46 publications

References 4 publications

Intercomparison of lamp and detector‐based UV‐irradiance scales for solar UV radiometry

Intercomparison of lamp and detector‐based UV‐irradiance scales for solar UV radiometry

2003 North American interagency intercomparison of ultraviolet spectroradiometers: scanning and spectrograph instruments.

Guidelines on the measurement of ultraviolet radiation levels in ultraviolet phototherapy: report issued by the British Association of Dermatologists and British Photodermatology Group 2015

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