Comparison of ultraviolet spectroradiometers in Antarctica

Bernhard, Germar; McKenzie, R. L.; Kotkamp, Michael; Wood, S.; Booth, Charles R.; Ehramjian, James C.; Johnston, P. V.; Nichol, Sylvia

doi:10.1029/2007jd009489

Cited by 11 publications

(9 citation statements)

References 49 publications

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“…At several sites, 50, 200 and 1000 W tungsten halogen lamps, which are used to monitor the stability and/or calibrate the Brewer spectrophotometers (e.g., Bais et al, 1996;Bernhard et al, 2008;Heikkilä et al, 2016), are also used for the temperature characterization of the instruments. These lamps are usually warm-colored, with a color temperature of ∼ 3000 K -thus they emit a significant amount of infrared radiation.…”

mentioning

confidence: 99%

Temperature dependence of the Brewer global UV measurements

et al. 2017

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Abstract. Spectral measurements of global UV irradiance recorded by Brewer spectrophotometers can be significantly affected by instrument-specific optical and mechanical features. Thus, proper corrections are needed in order to reduce the associated uncertainties to within acceptable levels. The present study aims to contribute to the reduction of uncertainties originating from changes in the Brewer internal temperature, which affect the performance of the optical and electronic parts, and subsequently the response of the instrument. Until now, measurements of the irradiance from various types of lamps at different temperatures have been used to characterize the instruments' temperature dependence. The use of 50 W lamps was found to induce errors in the characterization due to changes in the transmissivity of the Teflon diffuser as it warms up by the heat of the lamp. In contrast, the use of 200 or 1000 W lamps is considered more appropriate because they are positioned at longer distances from the diffuser so that warming is negligible. Temperature gradients inside the instrument can cause mechanical stresses which can affect the instrument's optical characteristics. Therefore, during the temperature-dependence characterization procedure warming or cooling must be slow enough to minimize these effects. In this study, results of the temperature characterization of eight different Brewer spectrophotometers operating in Greece, Finland, Germany and Spain are presented. It was found that the instruments' response changes differently in different temperature regions due to different responses of the diffusers' transmittance. The temperature correction factors derived for the Brewer spectrophotometers operating at Thessaloniki, Greece, and Sodankylä, Finland, were evaluated and were found to remove the temperature dependence of the instruments' sensitivity.

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Temperature dependence of the Brewer global UV measurements

et al. 2017

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“…Note that both instruments used total horizontal irradiance to derive ozone, which is generally a less accurate ozone measurement procedure than direct beam irradiance measurements. Some of the difference can also be explained by the different ozone and temperature vertical profiles used by the NIWA and BSI retrieval algorithms [14]. …”

Section: Total Ozonementioning

confidence: 99%

“…The Brewer spectrophotometer, the USDA U111 spectroradiometer, and earlier versions of the BSI spectroradiometer and RSS Spectrograph have been described in previous Intercomparison papers [2,3,4,5]. Several of the instruments have been described in other intercomparison campaigns or cited references [13,14,15,16,17]. Table 2 lists the characteristics of each instrument, and brief descriptions are given below.…”

Section: Introductionmentioning

confidence: 99%

“…The instrument is typically located on the roof of the NOAA ESRL building in Boulder, CO. The Biospherical Instruments SUV-150B ultraviolet-visible spectroradiometer system (NSF_SUV) is based on a scanning double-monochromator that is used in the NSF UV Arctic Program [14,20]. International participation was represented by a scanning double monochromator spectroradiometer from the Institute of Meteorology and Climatology, University of Hanover (IMUK_BEN).…”

Section: Introductionmentioning

confidence: 99%

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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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“…Fountoulakis et al: Temperature dependence of the Brewer global UV measurements B irradiance that reaches the Earth surface (Fioletov et al, 2001;Kerr and McElroy, 1993;McKenzie et al, 1999) and quantified the interaction between the solar UV irradiance, the Earth surface and the atmospheric components which mainly control its levels, such as ozone, sulfur dioxide, aerosols and clouds (e.g., Arola et al, 2003;Bais et al, 1993;Bernhard et al, 2007;Fioletov et al, 1998). Spectral measurements from Brewers have been used widely for climatological studies of biologically effective UV doses (e.g., Fioletov et al, 2003Fioletov et al, , 2009Kimlin, 2004), validation of satellite products (e.g., Arola et al, 2002;Bernhard et al, 2015;Kazadzis et al, 2009) and validation of radiative transfer models (Kazantzidis et al, 2001;Mayer et al, 1997). Lately, spectra from stations with long measurement records have been used for the study of the changes of the solar UV irradiance, showing that changes in air quality and climate have an important impact on its short-and long-term variability (De Bock et al, 2014;Fountoulakis et al, 2016a;Fragkos et al, 2016;Lakkala et al, 2017;Simic et al, 2011;Smedley et al, 2012;Zerefos et al, 2012).…”

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confidence: 99%

revised

Fountoulakis¹

2017

Preprint

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Spectral measurements of global UV irradiance recorded by Brewer spectrophotometers can be significantly affected by instrument-specific optical and mechanical features. Thus, proper corrections are needed in order to reduce the associated uncertainties to within acceptable levels. The present study aims to contribute to the reduction of uncertainties originating from changes in the Brewer internal temperature, which affect the performance of the optical and electronic parts, and subsequently the response of the instrument. Until now, measurements of the irradiance from various types of lamps at different temperatures have been used to characterize the instruments' temperature dependence. The use of 50 W lamps was found to induce errors in the characterization due to changes in the transmissivity of the Teflon diffuser as it warms up by the heat of the lamp. In contrast, the use of 200 or 1000 W lamps is considered more appropriate because they are positioned at longer distances from the diffuser so that warming is negligible. Temperature gradients inside the instrument can cause mechanical stresses which can affect the instrument's optical characteristics. Therefore, during the temperature-dependence characterization procedure warming or cooling must be slow enough to minimize these effects. In this study, results of the temperature characterization of eight different Brewer spec-trophotometers operating in Greece, Finland, Germany and Spain are presented. It was found that the instruments' response changes differently in different temperature regions due to different responses of the diffusers' transmittance. The temperature correction factors derived for the Brewer spectrophotometers operating at Thessaloniki, Greece, and Sodankylä, Finland, were evaluated and were found to remove the temperature dependence of the instruments' sensitivity.

show abstract

Comparison of ultraviolet spectroradiometers in Antarctica

Cited by 11 publications

References 49 publications

Temperature dependence of the Brewer global UV measurements

Temperature dependence of the Brewer global UV measurements

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

revised

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