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In this contribution we present the wavelength calibration of the travelling reference Brewer spectrometer of the Regional Brewer Calibration Center for Europe (RBCCE) at PTB in Braunschweig, Germany. The wavelength calibration is needed for the calculation of the ozone absorption coefficients used by the Brewer ozone algorithm. In order to validate the standard procedure for determining Brewer's wavelength scale, a calibration has been performed by using a tunable laser source at PTB in the framework of the EMRP project ENV59 ATMOZ "Traceability for the total column ozone". Here we compare these results to those of the standard procedure for the wavelength calibration of the Brewer instrument. Such a comparison allows validating the standard methodology used for measuring the ozone absorption coefficient with respect to several assumptions. The results of the laser-based calibrations reproduces those obtained by the standard operational methodology and shows that there is an underestimation of 0.8 % of the ozone absorption coefficients due to the use of the parametrized slit functions. ; This work has been supported by the European Metrology Research Programme (EMRP) within the joint research project ENV59 "Traceability for atmospheric total column ozone" (ATMOZ). The EMRP is jointly funded by the EMRP participating countries within EURAMET and the European Union.

From 25 May to 5 June 2015, the 10th regional intercomparison campaign of the Regional Brewer Calibration Center – Europe (RBCC-E) was held at El Arenosillo atmospheric sounding station of the Instituto Nacional de Técnica Aeroespacial (INTA). This campaign was jointly conducted by COST Action ES1207 EUBREWNET and the Area of Instrumentation and Atmospheric Research of INTA. A total of 21 Brewers, 11 single- and 10 double-monochromator instruments from 11 countries participated and were calibrated for total column ozone (TOC) and solar UV irradiance. In this 2015 campaign we have introduced a formal approach to the characterisation of the internal instrumental stray light, the filter non-linearity and the algorithm for correcting for its effects on the TOC calculations. This work shows a general overview of the ozone comparison and the evaluation of the correction of the spectral stray light effect for the single-monochromator Brewer spectrophotometer, derived from the comparison with a reference double-monochromator Brewer instrument. At the beginning of the campaign, 16 out of the 21 participating Brewer instruments agreed within better than ±1%, and 10 instruments agreed within better than ±0.5% considering data with ozone slant column between 100 and 900DU, which does not require instrumental stray light correction. ; This article is based upon work from COST Action 1207 EUBREWNET. This work has been supported by the European Metrology Research Programme within the joint research project ENV59 "Traceability for atmospheric total column ozone" (ATMOZ). The EMRP is jointly funded by the EMRP participating countries within EURAMET and the European Union. We also gratefully acknowledge further support by the Fundación General de la Universidad de La Laguna. This study and the campaigns were supported at large part by ESA project CEOS Intercalibration of ground-pectrometers and lidars (ESRIN contract 22202/09/I-EC).

Póster presentado en: 9th International Workshop on Sand/Duststorms and Associated Dustfall, celebrado en Tenerife del 22 al 24 de mayo de 2018. ; This work has been performed within the framework of COST Action ES1207 "The European Brewer Network" (EUBREWNET), supported by COST (European Cooperation in Science and Technology). Part of this work has been developed within the IDEAS+ project of the European Space Agency, in collaboration with LuftBlick Earth Observation Technologies. This work has been supported by the European Metrology Research Programme (EMRP) within the joint research project ENV59 "Traceability for atmospheric total column ozone" (ATMOZ). The EMRP is jointly funded by the EMRP participating countries within EURAMET and the European Union. These activities have been partially developed in the WMO-CIMO Testbed for Aerosols and Water Vapor Remote Sensing Instruments (Izaña, Spain). We also acknowledge the support of the Ministry of Economy and Competitiveness of Spain and the European Regional Development Fund (ERDF) under the POLARMOON (CTM2015-66742-R) and AEROATLAN (CGL2015-66299-P) projects. Stratospheric ozone and spectral UV baseline monitoring in the United Kingdom is supported by DEFRA, The Department for the Environment, Food, and Rural Affairs, since 2003. Some of the AERONET sun photometers used in this work have been calibrated within the AERONET Europe TNA, supported by the European Community-Research Infrastructure Action under the Horizon 2020 research and innovation program, ACTRIS-2 grant agreement No. 654109. We gratefully the acknowledge the PIs of the Madrid, Izaña, and Tamanrasset AERONET stations.