For the first time a series of automatic weather stations have been placed on a giant iceberg floating in the sea off Antarctica.
The iceberg, designated B-15A, is 144 km (90 miles) long and 48 km (20 miles) wide. It is part of a larger berg that broke away from the Ross Ice Shelf last March.
The weather stations were transported to the region by a patrolling US coast guard vessel in late January and flown on to the iceberg by helicopter. Scientists from the University of Wisconsin-Madison erected three stations roughly 45 m (150 feet) above the surface of the ocean.
Each station also includes a Global Positioning System (GPS) receiver, which will allow scientists to track the motion of the berg. They are already examining the first few weeks of data returned to them via satellite.
Tracking drift
Scientists installed an anemometer, to measure wind velocity and direction, as well as sensors to measure relative humidity, surface temperature and barometric pressure.
According to Dr Douglas MacAyeal of the University of Chicago they intend to begin analysing the iceberg's motion and the effects of collisions between the berg and the shoreline and ice at Cape Crozier in Antarctica.
The weather stations, assembled at the University of Wisconsin, are equipped with batteries and solar panels. Based on their use elsewhere in Antarctica, they could be expected to operate for as many as five years.
The instruments could help answer many questions about the behaviour of icebergs and their influence on the environment.
In particular scientists want to know how icebergs affect heat exchange between the atmosphere and the ocean and their influence on the amount of sea-ice.
Tracking the iceberg will help in the understanding of the factors that control iceberg movement and see if its path can be predicted.