Total ozone column intercomparison of Brewers, Dobsons, and BTS-Solar at Hohenpeißenberg and Davos in 2019/2020

Abstract. During the 2019/2020 measurement campaign at Hohenpeißenberg (Germany) and Davos (Switzerland) we compared well-established Dobson Brewer spectrometers (single- double-monochromator Brewer) with newer BTS array-spectroradiometer-based systems in terms of total ozone column (TOC) determination. The aim this study is to validate performance a longer-term TOC analysis over more than 1 year seasonal weather influences. Two different setups have been used – fibre-coupled entrance optic version by PMOD/WRC called Koherent diffusor from Gigahertz Optik GmbH BTS-Solar, which proved be simpler calibration. array-spectrometer-based calibrated traceability NMI, both versions retrieval algorithms are based on spectral measurements range 305 350 nm instead single-wavelength or wavelength pair as per Dobson. two BTS-based systems, however, fundamentally for assessment, whereby BTS-Solar turned out achieve significantly smaller drifts. intercomparison showed difference Brewers < 0.1 % an expanded standard deviation (k=2) 1.5 whole campaign. 1.7 2.7 mostly caused significant variation. To summarize, performed level comparison Hohenpeißenberg. very small dependence slant path better single-monochromator Brewer. strong variation due sensitivity its algorithm stratospheric temperature.