30 years of total column ozone and aerosol optical depth measurements using the Brewer spectrophotometer in Poprad-Gánovce, Slovakia

Abstract. Long-term measurement series are a rare but valuable source of information. The first measurements using the Brewer ozone spectrophotometer in Slovakia began at the Poprad-Gánovce station in August 1993. As a result, a 30-year series of measurements was completed in 2023. The primary goal of this study is to present the calculated values of total column ozone (TCO) and aerosol optical depth (AOD) derived from measurements conducted with the same Brewer spectrophotometer. Additionally, this time series of measurements is enriched with tropopause height values, made possible by aerological sounding measurements regularly conducted at the Poprad-Gánovce station. This work provides a climatological and long-term trend analysis of the time series for these three atmospheric characteristics. The data used in this study are closely tied to three environmental issues driven by human activities: ozone depletion, climate change, and air pollution caused by aerosols. No clear trend was observed for the annual TCO averages, while AOD at 320 nm exhibited a distinct decresing trend with a slope of −0.06 per decade. The lowest annual average of AOD at 320 nm was measured in 2020, corresponding to the first year of the COVID-19 pandemic. The highest increases in tropopause height were found in August, at 200 m per decade, and in September, at 210 m per decade. The largest declines in TCO occurred in the same months, with a rate of change of −3.5 DU per decade in August and −2.8 DU per decade in September.