Drift of pancake ice floes in the winter Antarctic marginal ice zone during polar cyclones

• Published in: Journal of Geophysical Research: Oceans
• Main Authors: Alberello, Alberto, Bennetts, Luke, Heil, Petra, Eayrs, Clare, Vichi, Marcello, MacHutchon, Keith, Onorato, Miguel, Toffoli, Alessandro
• Format: Article in Journal/Newspaper
• Language: English
• Published: 2020
• Subjects: Antarctic; Pancake; Southern Ocean; The Antarctic; Antarc*; Sea ice
• Online Access: https://ueaeprints.uea.ac.uk/id/eprint/82081/; https://ueaeprints.uea.ac.uk/id/eprint/82081/1/Published_Version.pdf; https://doi.org/10.1029/2019JC015418

High temporal resolution in situ measurements of pancake ice drift are presented, from a pair of buoys deployed on floes in the Antarctic marginal ice zone during the winter sea ice expansion, over 9 days in which the region was impacted by four polar cyclones. Concomitant measurements of wave-in-ice activity from the buoys are used to infer that the ice remained unconsolidated, and pancake ice conditions were maintained over at least the first 7 days. Analysis of the data shows (i) the fastest reported ice drift speeds in the Southern Ocean; (ii) high correlation of drift velocities with the surface wind velocities, indicating absence of internal ice stresses >100 km from the ice edge where remotely sensed ice concentration is 100%; and (iii) presence of a strong inertial signature with a 13 hr period. A Lagrangian free drift model is developed, including a term for geostrophic currents that reproduce the 13 hr period signature in the ice motion. The calibrated model provides accurate predictions of the ice drift for up to 2 days, and the calibrated parameters provide estimates of wind and ocean drag for pancake floes under storm conditions.