Field calibration unit for ultraviolet spectroradiometers

Ea, Early; Ea, Thompson; Disterhoft, P.

doi:10.1364/ao.37.006664

Cited by 32 publications

(34 citation statements)

References 5 publications

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“…Details of the CUCF field calibration unit are given in a separate paper [25]. Briefly, the field calibration unit consists of three circular baffles, 45 cm in diameter and separated by 15 cm, with a mount for a horizontal lamp on the top baffle.…”

Section: Methodsmentioning

confidence: 99%

“…The spectral irradiance of the 1000W FEL-type Tungsten halogen standard lamp was determined by CUCF in the horizontal position using a method similar to the one described previously and the stability is presented in section 4 [25]. The responsivity of each instrument was determined with the calibrated lamps mounted horizontally in the field calibration unit.…”

Section: Methodsmentioning

confidence: 99%

“…The spectral irradiance responsivities or simply responsivity of the instruments were determined by the participants using their own calibration systems and again by the CUCF using the NOAA/CUCF standard lamps and field calibration unit [25]. Several of the participating agencies use calibration systems that are linked to the CUCF either because the agency uses the CUCF personnel and equipment to calibrate their instruments or the agency purchases horizontally calibrated 1000W Tungsten lamps from the CUCF.…”

Section: Introductionmentioning

confidence: 99%

“…Several of the participating agencies use calibration systems that are linked to the CUCF either because the agency uses the CUCF personnel and equipment to calibrate their instruments or the agency purchases horizontally calibrated 1000W Tungsten lamps from the CUCF. Therefore, as in previous campaigns, the responsivity of all the instruments are measured using CUCF calibrated lamps to eliminate differences between solar irradiance measurements from the instruments due to the source of the calibration lamps and due to different field calibration units [25]. This avoids the potential bias or grouping of solar irradiance measurements that may occur if only a few instruments' calibration systems are linked to the same source.…”

Section: Introductionmentioning

confidence: 99%

“…The participants calibrated their instruments prior to the start of the Intercomparison during the set-up period. The CUCF standard lamps were operated in the field calibration unit whose performance was demonstrated at the previous Intercomparisons [25]. The CUCF calibrated instruments either the week prior to the start of the Intercomparison or the week after the end of the blind Intercomparison on DOY 172, 2003.…”

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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Section: Methodsmentioning

confidence: 99%

Section: Methodsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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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Spectral attenuation of global and diffuse UV irradiance and actinic flux by clouds

Mateos

Sarra

Bilbao

et al. 2014

Quart J Royal Meteoro Soc

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Measurements of spectral global and diffuse ultraviolet (UV) irradiance, and of spectral actinic flux were made jointly with determinations of cloud properties during a twomonth experimental campaign that took place in southern Italy in May-June 2010. The cloud modification factor (CMF) which is the ratio between the incoming radiation under cloudy and in cloud-free conditions, was obtained for the global (direct plus diffuse) and diffuse components of the irradiance, and for the actinic flux in the UV spectral range for overcast conditions. Measurements of the diffuse irradiance and actinic flux CMFs are very scarce, and are particularly important to characterize the radiation field and verify the behaviour of radiative transfer models in cloudy conditions. In addition to measurements, one-dimensional radiative transfer simulations are used to investigate the cloud influence on the spectral solar UV radiation. The analysis shows that the wavelength dependence of CMF for the global irradiance is mainly due to the normalization for cloud-free conditions. The CMF for the diffuse irradiance and for the actinic flux displays a strong dependence on the solar zenith angle. This dependence appears to be mainly driven by the large role played by the zenith radiation in overcast conditions. Radiative transfer model determinations of CMF satisfactorily reproduce observations.

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