An Exceptional Winter Sea-Ice Retreat/Advance in the

• Main Authors: Bellingshausen Sea Antarctica, J. Turner, S. A. Harangozo, J. C. King, W. M. Connolley, T. A. Lachlan-cope, G. J. Marshall
• Other Authors: The Pennsylvania State University CiteSeerX Archives
• Format: Text
• Language: English
• Published: 2002
• Subjects: Antarctic; Bellingshausen Sea; Rothera; Rothera Station; Southern Ocean; The Antarctic; Antarc*; Antarctica; Sea ice
• Online Access: http://citeseerx.ist.psu.edu/viewdoc/summary?doi=10.1.1.693.4109; http://www.antarctica.ac.uk/met/wmc/papers/Turner-et-al-Atmos-Ocean-sea-ice.pdf

ABSTRACT The exceptional sea-ice retreat and advance that occurred in the Bellingshausen Sea, Antarctica dur-ing August 1993 was the largest such winter event in this sector of the Antarctic during the satellite era. The rea-sons for this fluctuation of ice are investigated using passive microwave satellite imagery, ice motion vectors derived from the satellite data, in-situ meteorological reports and near-surface winds and temperatures from the European Centre for Medium-range Weather Forecasts (ECMWF) numerical weather prediction model. The ice edge retreat of more than 400 km took place near 80°W from approximately 1–15 August, although the south-ward migration of the ice edge was not continuous and short periods of advance were also recorded. Between 16 August and 2 September there was almost continuous sea-ice recovery. The rate of change of the ice edge loca-tion during both the retreat and advance phases significantly exceeded the southward and northward velocity components of ice within the pack, pointing to the importance of ice production and melting during this event. During the month, markedly different air masses affected the area, resulting in temperature changes from +2°C to –21°C at the nearby Rothera station. ‘Bulk ’ movement of the pack, and compaction and divergence of the sea ice, made a secondary, but still significant, contribution to the observed advance and retreat. The ice extent fluc-tuations were so extreme because strong meridional atmospheric flow was experienced in a sector of the Southern Ocean where relatively low ice concentrations were occurring. The very rapid ice retreat/advance was associat-