EUBREWNET RBCC-E Huelva 2015 Ozone Brewer Intercomparison

Redondas, Alberto; Carreño, Virgilio; León-Luis, Sergio F.; Hernández-Cruz, Bentorey; López-Solano, J.; Rodriguez-Franco, Juan J.; Vilaplana, José Manuel; Gröbner, Julian; Rimmer, John; Bais, A. F.; Savastiouk, Vladimir; Moreta, Juan R.; Boulkelia, Lamine; Jepsen, Nis; Wilson, Keith; Shirotov, V. V.; Karppinen, Tomi

doi:10.5194/acp-18-9441-2018

Cited by 20 publications

(16 citation statements)

References 23 publications

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“…Brewer spectrophotometers. 183 An intercomparison campaign of erythemal detectors took place in summer 2017 at PMOD/WRC in Davos Switzerland. 184 Finally, three spectroradiometers representing different networks in Australia and New Zealand took part in a two-month campaign in Melbourne, Australia in autumn 2013.…”

Section: Ground Based Systemsmentioning

confidence: 99%

Ozone—climate interactions and effects on solar ultraviolet radiation

Bais

Bernhard

McKenzie

et al. 2019

Photochem Photobiol Sci

149

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Section: Ground Based Systemsmentioning

confidence: 99%

Ozone—climate interactions and effects on solar ultraviolet radiation

Bais

Bernhard

McKenzie

et al. 2019

Photochem Photobiol Sci

149

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“…In a study done by Karppinen et al (2015), a method for correcting stray light has been presented that uses an additive correction, which is determined via instrument slit characterization and a radiative transfer model simulation and is then applied to the single Brewer data (Karppinen et al, 2015). The European Brewer Network is also applying stray-light corrections, which includes an iterative process that results in correcting the single Brewer data to agree with double Brewer data (Rimmer et al, 2018;Redondas et al, 2018). The first model requires measurements of the slit function and the latter method relies on a calibrated instrument, such as a double Brewer, to characterize the instrument and to determine a correction for stray light.…”

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confidence: 99%

A calibration procedure which accounts for non-linearity in single-monochromator Brewer ozone spectrophotometer measurements

et al. 2019

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Abstract. It is now known that single-monochromator Brewer spectrophotometer ozone and sulfur dioxide measurements suffer from non-linearity at large ozone slant column amounts due to the presence of instrumental stray light caused by scattering within the optics of the instrument. Because of the large gradient in the ozone absorption spectrum in the near-ultraviolet, the atmospheric spectra measured by the instrument possess a very large gradient in intensity in the 300 to 325 nm wavelength region. This results in a significant sensitivity to stray light when there is more than 1000 Dobson units (DU) of ozone in the light path. As the light path (air mass) through ozone increases, the stray-light effect on the measurements also increases. The measurements can be of the order of 10 %, low for an ozone column of 600 DU and an air mass factor of 3 (1800 DU slant column amount), which is an example of conditions that produce large slant column amounts. Primary calibrations for the Brewer instrument are carried out at Mauna Loa Observatory in Hawaii and Izana Observatory in Tenerife. They are done using the Langley plot method to extrapolate a set of measurements made under a constant ozone vertical column to an extraterrestrial calibration constant. Since the effects of a small non-linearity at moderate ozone paths may still be important, a better calibration procedure should account for the non-linearity of the instrument response. Studies involving the scanning of a laser source have been used to characterize the stray-light response of the Brewer (Fioletov et al., 2000), but until recently these data have not been used to elucidate the relationship between the stray-light response and the ozone measurement non-linearity. In a study done by Karppinen et al. (2015), a method for correcting stray light has been presented that uses an additive correction, which is determined via instrument slit characterization and a radiative transfer model simulation and is then applied to the single Brewer data (Karppinen et al., 2015). The European Brewer Network is also applying stray-light corrections, which includes an iterative process that results in correcting the single Brewer data to agree with double Brewer data (Rimmer et al., 2018; Redondas et al., 2018). The first model requires measurements of the slit function and the latter method relies on a calibrated instrument, such as a double Brewer, to characterize the instrument and to determine a correction for stray light. This paper presents a simple and practical method to correct for the effects of stray light, which includes a mathematical model of the instrument response and a non-linear retrieval approach that calculates the best values for the model parameters. The model can then be used in reverse to provide more accurate ozone values up to a defined maximum ozone slant path. The parameterization used was validated using an instrument physical model simulation. This model can be applied independently to any Brewer instrument and correct for the effects of stray light.

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“…Finally, it should be also mentioned that, within the framework of COST Action ES1207, A European Brewer Network (EUBREWNET), the RBCC-E and AEMET are developing a data server for EUBREWNET (http://rbcce.aemet. es/eubrewnet, last access: 5 July 2018) which will allow the calculation of the TOC in near real time (Rimmer et al, 2018). This completes the objectives of this COST action, which aims to establish a coherent network of Brewer monitoring stations in order to harmonise operations and develop approaches, practices and protocols to achieve consistency in quality control, quality assurance and coordinated operations.…”

Section: Introductionmentioning

confidence: 77%

Internal consistency of the Regional Brewer Calibration Centre for Europe triad during the period 2005–2016

et al. 2018

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Abstract. Total ozone column measurements can be made using Brewer spectrophotometers, which are calibrated periodically in intercomparison campaigns with respect to a reference instrument. In 2003, the Regional Brewer Calibration Centre for Europe (RBCC-E) was established at the Izaña Atmospheric Research Center (Canary Islands, Spain), and since 2011 the RBCC-E has transferred its calibration based on the Langley method using travelling standard(s) that are wholly and independently calibrated at Izaña. This work is focused on reporting the consistency of the measurements of the RBCC-E triad (Brewer instruments #157, #183 and #185) made at the Izaña Atmospheric Observatory during the period 2005–2016. In order to study the long-term precision of the RBCC-E triad, it must be taken into account that each Brewer takes a large number of measurements every day and, hence, it becomes necessary to calculate a representative value of all of them. This value was calculated from two different methods previously used to study the long-term behaviour of the world reference triad (Toronto triad) and Arosa triad. Applying their procedures to the data from the RBCC-E triad allows the comparison of the three instruments. In daily averages, applying the procedure used for the world reference triad, the RBCC-E triad presents a relative standard deviation equal to σ = 0.41 %, which is calculated as the mean of the individual values for each Brewer (σ157 = 0.362 %, σ183 = 0.453 % and σ185 = 0.428 %). Alternatively, using the procedure used to analyse the Arosa triad, the RBCC-E presents a relative standard deviation of about σ = 0.5 %. In monthly averages, the method used for the data from the world reference triad gives a relative standard deviation mean equal to σ = 0.3 % (σ157 = 0.33 %, σ183 = 0.34 % and σ185 = 0.23 %). However, the procedure of the Arosa triad gives monthly values of σ = 0.5 %. In this work, two ozone data sets are analysed: the first includes all the ozone measurements available, while the second only includes the simultaneous measurements of all three instruments. Furthermore, this paper also describes the Langley method used to determine the extraterrestrial constant (ETC) for the RBCC-E triad, the necessary first step toward accurate ozone calculation. Finally, the short-term or intraday consistency is also studied to identify the effect of the solar zenith angle on the precision of the RBCC-E triad.

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EUBREWNET RBCC-E Huelva 2015 Ozone Brewer Intercomparison

Cited by 20 publications

References 23 publications

Ozone—climate interactions and effects on solar ultraviolet radiation

Ozone—climate interactions and effects on solar ultraviolet radiation

A calibration procedure which accounts for non-linearity in single-monochromator Brewer ozone spectrophotometer measurements

Internal consistency of the Regional Brewer Calibration Centre for Europe triad during the period 2005–2016

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