Uncertainty analysis of total ozone derived from direct solar irradiance spectra in the presence of unknown spectral deviations

Vaskuri, Anna; Kärhä, Petri; Egli, Luca; Gröbner, Julian; Ikonen, Erkki

doi:10.5194/amt-11-3595-2018

Cited by 13 publications

(23 citation statements)

References 43 publications

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“…Contrary to BTS solar, the TOC retrieval from Koherent is using the full spectrum retrieval in the spectral range of 305 nm and 350 nm. The minimal least square algorithm as of Huber et al (1995) and Vaskuri et al (2018) includes for each TOC 375 retrieved data point also the calculation of other atmospheric parameters, such as aerosol optical depth and Rayleigh scattering with its parametrizations in the atmospheric model. This procedure of including the relevant atmospheric parameters of the actual existing atmosphere allows the operational use at other locations worldwide with different atmospheric conditions.…”

Section: Discussionmentioning

confidence: 99%

“…The BTS Solar has been calibrated for this campaign with a well-known spectral irradiance calibration setup in 70 cm distance at the Gigahertz-Optik ISO 17025 certified calibration laboratory (D-K-15047-01-00, D-PL-15047-17025-2020). This calibration showed to be robust and small measurement uncertainties of 2.5% (expanded measurement uncertainty k=2) in spectral irradiance can be achieved (Zuber et al, 2018b;Vaskuri et al, 2018). After 6 month a check of the calibration has been 205…”

Section: Bts Solarmentioning

confidence: 90%

“…The postprocessing was performed off-line with the following steps: a) converting the raw-counts of the readings to irradiance 230 using the laboratory calibration, b) wavelength shift correction using the MatShic software developed at PMOD/WRC (Egli, 2014) and c) retrieving TOC with a least squares minimization algorithm according to Huber et al (1995) and Vaskuri et al (2018).…”

Section: Koherentmentioning

confidence: 99%

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TOC intercomparison of Brewer, Dobson and BTS Solar at Hohenpeißenberg and Davos 2019/2020

Zuber¹,

Köhler²,

Egli³

et al. 2021

Preprint

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Abstract. In the 2019/2020 measurement campaign at Hohenpeißenberg (Germany) and Davos (Switzerland) we compared the well-established Dobson and Brewer spectrometers (single and double monochromator Brewer) with newer BTS array spectroradiometer based systems in terms of total ozone column (TOC) determination. The aim of this study is to validate the BTS performance in a longer-term TOC analysis over more than one year with seasonal and weather influences. Two different BTS setups have been used. A fibre coupled entrance optic version by PMOD/WRC called Koherent and a diffusor optic which proved to be simpler in terms of calibration from Gigahertz-Optik GmbH called BTS Solar. The array-spectrometer based BTS systems have been traceable calibrated to National Metrology Institutes (NMI) and the used TOC retrieval algorithms are based on spectral measurements in the range of 305 nm and 350 nm instead of single wavelength measurements as for Brewer or Dobson. The two BTS based systems, however, used fundamentally different retrieval algorithms for the TOC assessment, whereby the retrieval of the BTS solar turned out to achieve significantly smaller seasonal drifts. The intercomparison showed a deviation of the BTS Solar to Brewers of < 0.1 % with an expanded standard deviation of < 1.5 % within the whole measurement campaign. Koherent showed a deviation of 1.7 % with an expanded standard deviation of 2.7 % mostly given by a significant seasonal drift. Resulting, the BTS Solar performance is comparable to Brewers at the comparison in Hohenpeißenberg. The slant path slope is in-between double monochromator and single monochromator Brewer. Koherent shows a strong seasonal variation in Davos due to the sensitivity of its ozone retrieval algorithm to stratospheric temperature similar to the Dobson results.

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Section: Discussionmentioning

confidence: 99%

Section: Bts Solarmentioning

confidence: 90%

Section: Koherentmentioning

confidence: 99%

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TOC intercomparison of Brewer, Dobson and BTS Solar at Hohenpeißenberg and Davos 2019/2020

Zuber¹,

Köhler²,

Egli³

et al. 2021

Preprint

Self Cite

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“…The BTS2048-UV-S with OoR stray light correction already applied, is introduced and characterized for instance with respect to linearity, optical bandwidth, cosine response and wavelength accuracy in Zuber et al (2018b) and Zuber et al (2018a). A measurement uncertainty evaluation of this device is presented for direct irradiance measurements, calibrated with a low standard uncertainty calibration source of PTB, in Vaskuri et al (2018). In the following Figure 1, a schematic diagram is shown.…”

Section: Instrument Design and Characterisationmentioning

confidence: 99%

Combined Out of Range and in Band Stray Light Correction for Array Spectroradiometers

Zuber¹,

Ribnitzky²

2019

PROCEEDINGS OF the 29th Quadrennial Session of the CIE

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Insufficient stray light rejection of array spectroradiometers, in especially the UV spectral range, limits the application of these devices. One important example would be UV hazard measurements. This study shows that a combination of different stray light corrections methods can improve the stray light reduction performance of UV array spectroradiometers significantly, to meet these requirements. The ACGIH Eeff (identical ICNIRP) values measured with an uncorrected array spectroradiometer showed expected large deviations of 73% for a sunbed tanning lamp and 105% for a halogen lamp, relative to a double monochromator reference. With the applied combined Out-of-Range and In-Band stray light correction method, these measurements were within 3% of the reference double monochromator based system. Furthermore, the measurements showed a detection limit of 2E-5 W/m²/nm for the double monochromator and comparable 3E-5 W/m²/nm for the stray light corrected array spectroradiometer. This was in contrast to 5E-4 W/m²/nm for the uncorrected array spectroradiometer. The results suggest that photobiological safety measurements according to IEC / DIN EN 62471 are possible with the applied combined stray light correction method for the used spectroradiometer.

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“…The absolute measurement uncertainty of the UV-BTS for spectral irradiance was determined with a Monte Carlo based uncertainty evaluation (Vaskuri et al 2018). The resulting expanded measurement uncertainty (k = 2) was estimated as 2.5%.…”

Section: Measurement Campaign and Data Processingmentioning

confidence: 99%

Global spectral irradiance array spectroradiometer validation according to WMO

Zuber¹,

Ribnitzky²,

Tobar

et al. 2018

Meas. Sci. Technol.

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Solar spectral irradiance measured by two recently developed array spectroradiometers (called UV-BTS and VIS-BTS) are compared to the results of a scanning double monochromator system which is certified as a travelling reference instrument by the Network for the detection of atmospheric composition change (NDACC) and fulfils the specifications of S-2 UV instruments of the world meteorological organization (WMO). The comparison took place between 15 and 18 May 2017 at the Institute of Meteorology and Climatology of the University of Hanover (IMuK) between 4:00 and 17:00UTC. The UV-BTS array spectroradiometer is equipped with special hardware to significantly reduce internal stray light which has been the limiting factor of many array spectroradiometers in the past. It covers a wavelength range of 200 nm-430 nm. The VIS-BTS covers a wider spectral range from 280 nm up to 1050 nm, and stray light reduction is achieved by mathematical methods. For the evaluation, wavelength integrated quantities and spectral global irradiance are compared. The deviation for UV index measured by the UV-BTS, is within ±1% for solar zenith angles (SZA) below 70° and increased to a maximum of ±3% for SZA between 70° and 85° when synchronisation between measurements was possible. The deviation of global spectral irradiance is smaller ±2.5% in the spectral range from 300 nm to 420 nm (evaluated for SZA < 70°). The VIS-BTS achieved the same deviation for blue light hazard as the UV-BTS for the UV index. The evaluations of global spectral irradiance data of the VIS-BTS show a deviation smaller than ±2% in the spectral range from 365 nm to 900 nm (evaluated for SZA < 70°). Below 365 nm, the deviation rises up to ±7% at 305 nm due to remaining stray light. The agreement within the limited time of the intercomparison is considered to be satisfactory for a number of applications and provides a good basis for further investigations.

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Uncertainty analysis of total ozone derived from direct solar irradiance spectra in the presence of unknown spectral deviations

Cited by 13 publications

References 43 publications

TOC intercomparison of Brewer, Dobson and BTS Solar at Hohenpeißenberg and Davos 2019/2020

TOC intercomparison of Brewer, Dobson and BTS Solar at Hohenpeißenberg and Davos 2019/2020

Combined Out of Range and in Band Stray Light Correction for Array Spectroradiometers

Global spectral irradiance array spectroradiometer validation according to WMO

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