EUBREWNET RBCC-E Huelva 2015 Ozone Brewer Intercomparison

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 Tecnica 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 900 DU, which does not require instrumental stray light correction.