&lt;title&gt;Performance tests of two Robertson-Berger-type UV meters Solar Light Model 500 and 501&lt;/title&gt;

Leszczynski, Kirsti; Jokela, Kari; Visuri, Reijo; Huurto, Laura; Simola, Janne; Koskela, Tapani; Taalas, P.; Aarva, Antti

doi:10.1117/12.163508

Cited by 7 publications

(5 citation statements)

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“…Usually, one or two steps more are required for the spectroradiometric calibration because most solar UV-monitoring sites derive their calibrations from a local reference standards laboratory which realizes its scale for the spectral UV irradiance with 1 kW halogen lamps calibrated in a national primary standards laboratory. Finally, spectroradiometers are used as a transfer standard to calibrate broadband radiometers outdoors in solar radiation, as described by Leszczynski et al [1996Leszczynski et al [ , 1998]. The expanded uncertainties certified by some of the most qualified standards laboratories for 1 kW halogen standard lamps are less than _+1.5% at wavelengths above 280 nm [Walker et al, 1987;Sperling et al, 1996]…”

Section: Calibration Chains For Solar Uv Radiometersmentioning

confidence: 99%

“…The uncertainties indicated (2•r values) represent state of the art values for solar UV measurements above 300 nm. The introduction of improved diffusers [Bernhard and Seckmeyer, 1997], cosine correction of the diffuser [Seckmeyer and Bernhard, 1993;Leszczynski et at., 1993], and the use of the Fraunhofer lines of solar radiation to reduce slit function and wavelength-dependent errors [Slaper et at., 1995] have resulted in significant improvement in the quality of the best solar UV measurements. As a result, the uncertainty Copyright 2000 by the American Geophysical Union.…”

Section: Introductionmentioning

confidence: 99%

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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: Calibration Chains For Solar Uv Radiometersmentioning

confidence: 99%

Section: Introductionmentioning

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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“…Solar measurements are not carried out on a regular basis by the STUK, but for the purpose of calibration and testing and for collecting solar UV data for research and UV climatology [6,7]. All the broadband meters are tested by the STUK with respect to spectral and cosine responses and temperature sensitivity before they go into service [8,9]. The STUK calibrates the broadband meters of the FMI and an intercomparison between the Brewer and OL 742 spectroradiometers is carried out annually.…”

Section: Ultraviolet Radiation Measurements In Finlandmentioning

confidence: 99%

“…The radiometric characteristics of the OL 742 have been measured in our laboratory, and the solar measurements are numerically corrected with respect to the most significant sources of error, e.g. the non-ideal cosine response, inaccuracy of the wavelength scale and the temperature sensitivity of the optics head [8][9][10]. The cosine error is minimized by applying an elevationangle-dependent cosine correction function, the value of which decreases from 1,11 at a solar elevation angle of 20 to 1,08 at an elevation of 53 .…”

Section: Ol 742 Spectroradiometermentioning

confidence: 99%

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Calibration of the broadband radiometers of the Finnish solar ultraviolet monitoring network

Leszczynski¹,

Jokela²,

Visuri³

et al. 1995

Metrologia

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The present solar ultraviolet (UV) monitoring network of the Finnish Meteorological Institute consists of seven sites equipped with erythemally-weighted broadband radiometers. Two of the sites are also equipped with a Brewer spectroradiometer. The Finnish Centre for Radiation and Nuclear Safety is responsible for testing and calibration of the broadband radiometers. An Optronic 742 spectroradiometer is used as a reference instrument, and the broadband radiometers are calibrated against the Optronic 742 in solar radiation. The Optronic 742 is calibrated against 1000 W FEL lamps traceable to the NIST. The errors caused by nonideal radiometric characteristics of the Optronic 742 are numerically corrected. The uncertainty (2 σ) of solar UV measurements with the Optronic 742 is estimated to be ±8 % at 310 nm and the uncertainty of the spectroradiometric solar calibration of the Solar Light Model 501 radiometers is estimated to be 11 %.

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Methods to Derive Geographical Differences of UV Irradiances

Seckmeyer¹,

Albold²,

Mayer³

1997

Solar Ultraviolet Radiation

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<title>Performance tests of two Robertson-Berger-type UV meters Solar Light Model 500 and 501</title>

Abstract: ABSTRACF Solar calibrations and laboratory tests were performed for erythemally weighted Robertson-Berger type UV radiometers.162

Cited by 7 publications

References 1 publication

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

Calibration of the broadband radiometers of the Finnish solar ultraviolet monitoring network

Methods to Derive Geographical Differences of UV Irradiances

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