Abstract
<title>Abstract</title> <p> In 2021, a double monochromator Brewer spectrophotometer was installed in Reykjavik, Iceland, complementing the long-term Dobson total column ozone (TCO) observations at this site. To assess the spatial representativeness of this TCO time series, the reanalyzed ERA5 TCO daily mean values in the area north of N 40° have been analyzed. A good agreement was found between the Brewer and ERA5 TCO, with almost no systematic bias and a RMSE of 7.7 DU (2.1%). The results of the representativeness study show that the deseasonalized Reykjavik TCO time series is able to capture major regional-scale TCO patterns, but local variations may cause substantial deviations from the regional mean TCO. The correlation fields are largest in late winter and spring, when TCO is affected by large-scale dynamical processes. At individual grid points, correlations exceed 0.90 at approximately 300–500 km from Reykjavik, increasing to more than 1000 km for area-averaged values. A comparison with other Arctic sites revealed a strong relationship between the size of the high-correlation area and the TCO variability ( <italic>r</italic> = 0.88 for areas with correlations above 0.90). This study demonstrates that Reykjavik is a suitable location for long-term TCO monitoring in the North Atlantic sector, effectively filling the spatial gap between the stations in Greenland and Scandinavia. </p>