Five years of ground-based MAX-DOAS measurements in Vienna, Austria: Overview and highlights of the VINDOBONA project

Satellite observations of tropospheric nitrogen dioxide (NO2) form an important basis for estimating the environmental impact of nitrogen oxide emissions and for assessing the impact of atmospheric pollution on human health. There is a great need to evaluate the accuracy of satellite tropospheric NO2 vertical columns by validating these data products against other measurements, for example ground-based Multi-AXis Differential Optical Absorption Spectroscopy (MAX-DOAS) observations. Moreover, the conversion of tropospheric NO2 vertical columns to surface NO2 concentrations, which is of great interest for exposure studies, requires new scientific approaches to reduce existing uncertainties.

From 2016 to 2021, the VINDOBONA (VIenna horizontal aNd vertical Distribution OBservations Of Nitrogen dioxide and Aerosols) project was carried out in Vienna, Austria. One major goal of the VINDOBONA project was to improve the spatial representativeness of ground-based MAX-DOAS observations in urban environments by making use of measurements taken simultaneously at three locations in Vienna, each covering a range of azimuth directions. By comparing MAX-DOAS integrated NO2 concentrations along horizontal columns with each other as well as with in-situ NO2 data from local air quality measuring stations, interesting insights into the spatial distribution of NO2 in Vienna was gained. Even more insights and in fact, a higher spatial variability of NO2 on the scale of the city was found from case study-based DOAS horizontal measurements taken on the rotating Café of the Danube Tower. These results highlight the need to refine the colocation of ground-based MAX-DOAS with satellite pixels in future validation activities.

The impact of lockdowns on ambient NO2 pollution during the COVID-19 pandemic as well as the value of MAX-DOAS measurements of other species (formaldehyde, glyoxal, and aerosols), which form the basis of past and ongoing research activities, will also be highlighted.

 

 

 

Acknowledgements: This research has been financially supported by the Austrian Science Fund (grant no. I 2296-N29), the German Research Foundation (grant no. Ri 1800/6-1), and A1 Telekom Austria.