200-year ice core bromine reconstruction at Dome C (Antarctica): observational and modelling results

Bromine enrichment (Br-enr) has been proposed as an ice core proxy for past sea-ice reconstruction. Understanding the processes that influence bromine preservation in the ice is crucial to achieve a reliable interpretation of ice core signals and to potentially relate them to past sea-ice variability. Here, we present a 210 years bromine record that sheds light on the main processes controlling bromine preservation in the snow and ice at Dome C, East Antarctic plateau. Using observations alongside a modelling approach, we demonstrate that the bromine signal is preserved at Dome C and it is not affected by the strong variations in ultraviolet radiation reaching the Antarctic plateau due to the stratospheric ozone hole. Based on this, we investigate whether the Dome C Br-enr record can be used as an effective tracer of past Antarctic sea ice. Due to the limited time window covered by satellite measurements and the low sea-ice variability observed during the last 30 years in East Antarctica, we cannot fully validate Br-enr as an effective proxy for past sea-ice reconstructions at Dome C.

Automated summary

Based on a 210-year bromine record, this study finds that the bromine signal in ice at Dome C in East Antarctica is preserved and not influenced by variations in ultraviolet radiation. However, due to limited satellite measurements and low sea-ice variability in the past 30 years, the effectiveness of bromine enrichment as a proxy for past sea-ice reconstructions at Dome C is still uncertain.