On the variability of atmospheric ²²²Rn activity concentrations measured at Neumayer, coastal Antarctica

Abstract

Abstract. We report on continuously measured 222Rn activity in near surface air at Neumayer Station in the period 1995 through 2011. This 17 yr record showed no long-term trend and has overall mean ± standard deviation of (0.019 ± 0.012) Bq m−3. A distinct and persistent seasonality could be distinguished with maximum values of (0.028 ± 0.013) Bq m−3 from January through March and minimum values of (0.015 ± 0.009) Bq m−3 from May through 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 SIE variability as a significant driver of the annual 222Rn cycle.