THE sea ice ringing Antarctica is revealing its secrets for the first time, thanks to a sub that can rove on its own far under the ice. With its help, scientists are starting to gain a comprehensive picture of Antarctic sea ice thickness 鈥� a critical unknown in current climate models.
Polar oceanographer Mark Brandon at the Open University in Milton Keynes, UK, wanted to fill that gap in the global climate picture. 鈥淚n the Arctic there have been tens of thousands of kilometres of ice-thickness data collected by nuclear submarines,鈥� he says. 鈥淚n the Antarctic, sea ice data has been collected by people drilling holes in the ice and dropping a tape measure through.鈥�
So Brandon and marine biologists Andrew Brierley and Paul Fernandes seized on a chance to use the latest in autonomous undersea vehicles, a machine called Autosub 2 built by the Southampton Oceanography Centre in the UK. It is a battery-driven, torpedo-shaped submersible that 鈥渇lies鈥� independently for up to 12 hours.
Advertisement
Autosub 2 was untested when Brandon suggested taking it to the Antarctic, but it has now made successful forays as far as 27 kilometres in from the edge of the ice near Pine Island Bay in the Amundsen Sea, firing sonar pulses upwards to measure the thickness of the ice shelf. The team is now analysing the 500 kilometres of data the sub brought back. They see it as the first step in building a much-needed comprehensive map of Antarctic sea ice thickness to assess the impact of global warming.
Climate physicist Seymour Laxon at University College London, who recently reported drastic ice-thinning in the Arctic (New 杏吧原创, 1 November, p 12), describes gathering data like this for the Antarctic as 鈥渙ne of the most important things we need to do鈥�.
