Antarctic sea ice shows a large degree of regional variability, which is partly driven by severe weather events. Here we bring a new perspective on synoptic sea ice changes by presenting the first in situ observations of an explosive extratropical cyclone crossing the winter Antarctic marginal ice zone (MIZ) in the South Atlantic. This is complemented by the analysis of subsequent cyclones and highlights the rapid variations that ice‐landing cyclones cause on sea ice: Midlatitude warm oceanic air is advected onto the ice, and storm waves generated close to the ice edge contribute to the maintenance of an unconsolidated surface through which waves propagate far into the ice. MIZ features may thus extend further poleward in the Southern Ocean than currently estimated. A concentration‐based MIZ definition is inadequate, since it fails to describe a sea ice configuration which is deeply rearranged by synoptic weather.

Full-scale measurements on polar research vessels present an opportunity to advance the state-of-the-art in ship design through high-quality long-term measurements of environmental conditions and ship responses. The approaches, data analytics and synoptic results are presented for a comprehensive measurement campaign on a modern polar supply and research vessel, the SA Agulhas II. It is recognised that the real-time analysis and utilisation of such measurements could benefit the insightful operation and management of this vessel. To this end, the conceptual design of a monitoring and decision-aiding system is presented. Results indicate that significant potential beckons in the integrated acquisition, analysis and utilisation of full-scale ship-board measurements provided that this diverse data can be aggregated, analysed, visualised and interpreted in real time.