Search for the secrets of Arctic ice floes turns to frozen core of central Hamburg

九月 10, 1999

Researchers into sea ice have an urban centre for their work. David Thomas reports

Polar research in Hamburg city centre sounds an unlikely undertaking. It can be cold and bleak in northern Germany, but not that cold.

At the Hamburg Ship Model Basin (HSVA), however, researchers using powerful cooling units and careful seeding with water droplets can convert tanks the size of football pitches into expanses of polar pack ice.

Temperatures plummet to -20°C, a skim of ice forms within hours, and after a day or so it is thick enough to walk on. "This is a great tool for sea-ice physicists, chemists and biologists," said Christian Haas of the Alfred Wegener Institute for Polar Research in Bremerhaven. He is leading a consortium of European scientists who use the facilities to back up field research conducted in the Arctic and Antarctic oceans.

The tanks were designed to test oil rigs and ship models, though the strength of the ice has to be scaled down by adding alcohol or uric acid to match the scaled-down test models. The ice in the latest experiments is made from artificial seawater without scaling and is very like that in the ocean, Dr Haas said.

Polar pack ice can be more than 10 metres thick. At the height of winter it covers up to 20 million square kilometres in the Antarctic and 14 million in the Arctic. The ice's formation, consolidation and subsequent melting is fundamental to ocean circulation, air/ocean exchange, and the transport of sediments and oil. It plays a key role in shaping the global climate, and climate change might in turn affect the extent, thickness and other properties of the ice.

Expeditions to research the ice require lots of time and money. Running costs for a research icebreaker hover around Pounds 20,000 a day before extras such as helicopter support, scientific equipment and the scientists themselves.

"By harnessing facilities such as the Hamburg ice tank, we can conduct fundamental sea-ice research with the luxury of having time to look at processes under controlled environmental conditions," Dr Haas said.

The experiments have been conducted largely on the physical and chemical properties of sea ice. In the future, it should be possible to study the effect sea ice has on life in the surface waters of the ocean.

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