<p>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° S at 150° W during the winter season. These activities are carried on in the framework of the ACCESS and SWIMMING projects of the PNRA.<br />Our findings show that the northward deflection of the southern Antarctic Circumpolar Current front is driven by the Pacific Antarctic Ridge (PAR) and is associated with the enhanced sea-ice advance. The PAR also constrains anticyclonic and cyclonic eddy trajectories, limiting their interaction with the sea-ice edge. These factors, within the 160° W - 135° W sector, determine an average SIE increase of 61,000 km2 and 46,293 km2 per year more than the upstream and downstream areas, respectively.</p>

The accelerating rate of climate change is one of the main challenges humanity faces in the coming decades (IPCC, 2021). However, variations in the rates of change make it difficult to develop mitigation or adaptation strategies. Ice albedo feedback is a fundamental element of the global climate because it is responsible for the rapid oscillation between glacial and interglacial stages (Hall, 2004;Marcianesi et al., 2021). Sea-ice variability also affects freshwater fluxes that impact overturning circulation (Liu et al., 2022;Meccia et al., 2022;Wu et al., 2021), as well as biological processes and polar food webs (Castellani et al., 2020;Massom & Stammerjohn, 2010). Therefore, the study and monitoring of the variability in Antarctic Sea-ice concentration (SIC) and extent (SIE) is crucial for understanding and forecasting future of changes to Earth's climate (Parkinson, 2004).The Southern Ocean (SO) can be characterized by large variations in SIC and SIE at both local and regional scales. For example, observations of the Bellingshausen Sea (in the Pacific sector of the SO) show strong decrease during the last four decades (