Finnish researchers stationed in Antarctica

Researchers from the University of Helsinki are monitoring the quality of the snow in Antarctica.

Finnish researchers stationed in Antarctica

Antarctica is like a great mirror. Covered by ice and snow, the bright, white surface of Antarctica reflects back into space over 90 per cent of the solar energy it receives. If the mirror grows darker, humankind will be facing increasingly overwhelming problems caused by climate change.

For this reason, changes in the quality of snow in Antarctica are monitored closely by researchers.

– When the water content of snow increases, its reflection capacity decreases dramatically. Wet snow reflects only 50 per cent of the radiation that falls upon it. The decrease in reflectivity from 90 to 50 per cent means a five-fold increase in the amount of solar energy absorbed by the snow, and the process is self-accelerating, says Matti Leppäranta, Professor of Physics.

The Finnish physicists study the surface snow in Antarctica up to a depth of ten meters: they measure the density, hardness, electrical conductivity, crystal size and shape, pH value, salinity and more.

During the ten-year follow-up period, there have been no significant changes in the snow, and the variation that has occurred can be explained by the different conditions each summer.

Different kind of snow

Snow in Antarctica is different from that on the streets of Helsinki. Its crystal size is smaller, and it is particularly this type of snow that reflects radiation the most effectively. The reflective capacity of the snow cover is different for other reasons, too.

– In Northern Europe, low pressure weather systems quickly turn snow quite wet, whereas in Antarctica, apart from the coastal area, the snow is very dry. In fact, in the summer, more snow evaporates than melts.

Even the slightest impurities will significantly increase the amount of heat absorbed by snow. In Finland this can be seen in how the snow around a wood-heated sauna will melt faster than snow further away – this is because of the tiny soot particles that will have landed on it via the chimney. In Antarctica, the snow is still very clean.

– There is so little black carbon in the Antarctic snow that it cannot be seen with the naked eye. I'm not sure it has any impact, says Leppäranta.

Helsinki University Bulletin: Ten meters of snow » »

Text: Antti Kivimäki
Photo: Finnarp 2010
2.3.2011
www.helsinki.fi/digitalcommunications


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