We report on continuously measured 222Rn activity concentrations in near-surface air at Neumayer Station in the period 1995-2011. This 17-year record showed no long-term trend and has overall mean ± standard deviation of (0.019 ± 0.012) Bq/m3. A distinct and persistent seasonality could be distinguished with maximum values of (0.028 ± 0.013) Bq/m3 from January to March and minimum values of (0.015 ± 0.009) Bq/m**3 from May to October. Elevated 222Rn activity concentrations were typically associated with air mass transport from the Antarctic Plateau. Our results do not support a relation between enhanced 222Rn activity concentrations at Neumayer and cyclonic activity or long-range transport from South America. The impact of oceanic 222Rn emissions could not be properly assessed but we tentatively identified regional sea ice extent (SIE) variability as a significant driver of the annual 222Rn cycle.

Supplement to: Weller, Rolf; Levin, Ingeborg; Schmithüsen, Dominik; Nachbar, Mario; Asseng, Jölund; Wagenbach, Dietmar (2014): On the variability of atmospheric 222Rn activity concentrations measured at Neumayer, coastal Antarctica. Atmospheric Chemistry and Physics, 14(8), 3843-3853