Antarctic Sea Ice in the IPY

Antarctic Sea Ice covers an area of 20 million km2 at maximum extent and therefore represents an areal coverage larger than either the Arctic ice cover or the Antarctic continent. Studies of Antarctic sea ice in the modern era were only initiated well after the IGY, with the advent of passive microwave satellite coverage in 1973, followed by the use of several countries icebreaking research vessels over the last two decades. Useful knowledge of basic ice thickness, properties and processes is being addressed by an ice observations programs and several process studies, but the scale of activity is well below that conducted for the Arctic ice cover. The absence of submarine activity in the Antarctic which has provided large scale information on the changing Arctic ice thickness distribution is particularly notable as a critical measurement in understanding climate impact. As well, only two short term drift stations (Ice Station Weddell in 1992 and Ice Station Polarstern in 2004) have or will provide limited time series information on sea ice and ocean processes compared to multiple drift stations and yearlong experiments in the Arctic, dating back to IGY. The two technologies of Autonomous Underwater Vehicles specifically designed for long-range ice operations (500km) (e.g. Autosub Under Ice) and the recently developed international icebreaking research vessel capability for the Antarctic therefore gives an opportunity for two International Polar Year programs to provide critical information for the Antartic sea ice cover commensurate with our knowledge of the Arctic. The proposed programs are: 1. A circumpolar survey of the Antarctic sea ice thickness distribution at near maximum extent using two ship-based autonomous underwater vehicles and several countries' icebreakers. 2. An International Ice Drifting Station in the Bellingshausen-Amundsen-Ross Sea using icebreakers and drifting buoys to characterize the sea ice, ocean and climate in this unknown region of Antarctic multiyear ice. These measurements will provide directly comparable measurements to those of the Arctic Ocean' ice cover as well as a year-long snapshot of ice, ocean and climate conditions useful for numerical model verification for climate change prediction. New venues for training and experience of oceanographers, climate and sea ice scientists, and numerical modelers will also be provided to examine the many future opportunites in the Antarctic.