Antarctic Atmospheric River Interactions with Sea Ice

Atmospheric rivers (ARs), though infrequent over Antarctica, wield a substantial influence on the Antarctic ice mass balance. Previous studies highlight their significance, attributing 35% of the interannual precipitation variability over the Antarctic Ice Sheet (AIS) to ARs. There is an expanding body of work examining the relationship between ARs and sea ice in the Arctic, while work in Antarctica is just emerging. In the Arctic, ARs have been found to influence sea ice mass balance through dynamic and thermodynamic forcings. Recent research suggests a similar relationship between ARs and sea ice in the Antarctic, where ARs trigger intense sea ice reduction in marginal ice zones primarily through thermodynamic processes.
Our ongoing study investigates the interaction between ARs and Southern Ocean sea ice. This project encompasses an exploration of AR impacts on sea ice seasonality, location, thickness, and concentration, along with an examination of sea ice influence on AR intensity, characteristics, and dissipation. This presentation first shows comparisons between AR tracking algorithms and datasets based on integrated vapor transport (IVT) and meridional integrated vapor transport (vIVT). Centering the difference between IVT and vIVT AR detection algorithms (ARDTs) in polar regions, our study takes an impacts-based perspective in assessing ARDTs. Results of this comparison highlight the importance of AR definitions and tracking methodology. For example, in the cold season, the IVT-based dataset favors ARs to the west of the Antarctic Peninsula (AP) in the Bellingshausen Sea, while the vIVT-based dataset favors ARs on the eastern side of the AP in the Weddell Sea. Both regions are critical when considering Antarctic sea ice change and the processes responsible, but conclusions differ based on the ARDT. Our work then examines AR thermodynamic characteristics using ERA5 reanalysis data to further explore the relationship between AR activity and sea ice concentration from passive microwave observations. Initial analyses reveal overlapping anonymously high AR activity in seasons with anomalous sea ice decline.