UAV sheds new light on Antarctic sea ice
The first detailed, high-resolution 3-D maps of Antarctic sea ice have been developed using an underwater robot, with scientists from the United Kingdom, United States, and Australia successfully demonstrating how new technology provides accurate ice thickness measurements from areas that were previously too difficult to access.
The results, published in the journal Nature Geoscience, step up the pace of research in the Polar Regions aimed at understanding the dramatic sea ice changes in the context of climate change.
Scientists use a range of technologies and techniques to measure sea ice thickness. Satellite observations can measure large-scale thickness from space, but interpreting the data accurately can be difficult due to snow cover on the ice.
Meanwhile, measurements made on the sea ice by drilling holes – together with visual observations from ships – are critical for building a more complete picture, but difficulties in getting access to thicker areas of sea ice leaves gaps in the data.
Overcoming these difficulties is the autonomous underwater vehicle (AUV) known as 'SeaBED', which provides scientists with an invaluable new tool to fill these gaps.
While most oceanographic survey instruments look down at the seafloor, 'SeaBED' was fitted with upward-looking sonar in order to measure and map the underside of sea ice floes.
The AUV operated at a depth of 20 to 30 metres and was driven in a lawnmower pattern. These lines of data were merged to form high-resolution 3D bathymetric surveys of the underside of the ice.
The yellow 'SeaBED' robot, which is approximately two metres long and weighs nearly 200 kilograms, has a twin-hull design that gives the robot enhanced stability for low- speed photographic surveys.
According to Dr Jeremy Wilkinson from British Antarctic Survey (BAS), the AUV missions provided real insights into the nature of Antarctic sea ice – akin to looking through a microscope.
With the assistance of the AUV, ice up to 17 metres thick can be measured in far greater detail.
The team deployed AUVs as part of two Antarctic cruises (IceBell and SIPEX-2) in 2010 and 2012 in the austral spring, on board British Antarctic Survey's 'James Clark Ross' and on the Australian icebreaker 'Aurora Australis', respectively.
Three locations around the Antarctic Peninsula were mapped – the Weddell, Bellingshausen and Wilkes Land sectors covering an area of 500,000 square metres, the size of 100 football pitches.
The research was carried out by scientists at the Institute of Marine and Antarctic Studies (Australia), Antarctic Climate and Ecosystem Cooperative Research Centre (Australia), Woods Hole Oceanographic Institution (USA) and British Antarctic Survey (UK).
