The Role of the Pacific-Antarctic Ridge in Establishing the Northward Extent of Antarctic Sea-Ice

Monitoring the Antarctic sea-ice is essential for improving our knowledge of the Southern Ocean. We used satellite sea-ice concentration data for the 2002-2020 period to retrieve the sea-ice extent (SIE) and analyze its variability in the Pacific sector of the Southern Ocean. Results provide observational evidence of the recurring formation of a sea-ice protrusion that extends to 60 degrees S at 150 degrees W during the winter season. Furthermore, we discuss how the Pacific-Antarctic Ridge (PAR) influences this phenomenon. Our findings show that the northward deflection of the southern Antarctic Circumpolar Current front is driven by the PAR and is associated with the enhanced sea-ice advance. The PAR also constrains eddy trajectories, limiting their interaction with the sea-ice edge. These factors, within the 160 degrees W-135 degrees W sector, cause an average SIE increase of 61,000 km(2) and 46,293 km(2) per year more than the upstream and downstream areas, respectively.

Automated summary

Monitoring Antarctic sea-ice is crucial for understanding the Southern Ocean, and our study utilized satellite data from 2002-2020 to analyze the sea-ice extent in the Pacific sector. We found evidence of a recurring sea-ice protrusion extending to 60 degrees S at 150 degrees W during winter, influenced by the Pacific-Antarctic Ridge (PAR). The PAR also affects the northward deflection of the Antarctic Circumpolar Current front and limits eddy trajectories, resulting in increased sea-ice advance.