Satellites can help Arctic grazers survive killer winter storms

Reindeer graze on the Norwegian island of Spitsbergen in this 1992 photo. Many reindeer on Spitsbergen have starved to death because of rain-on-snow events, in the same way as musk... Click here for more information.

Rain falling on snow sounds like a relatively harmless weather event, but when it happens in the far north it can mean lingering death for reindeer, musk oxen and other animals that normally graze on the Arctic tundra.

That was the case in October 2003 on Canada's Banks Island, at the edge of the Beaufort Sea inside the Arctic Circle. Rain fell for several days on top of a 6-inch snow cover, and the rain seeped through the snow to the soil surface. The temperature then plunged and the water became a thick layer of ice that lasted the winter and prevented browsing animals from reaching their food supply of lichens and mosses at the soil's surface. Some 20,000 musk oxen starved to death.

"Starvation happened over a period of many months and no one knew until they went up to do the population count the next spring," said Thomas Grenfell, a University of Washington research professor of atmospheric sciences who has studied the Banks Island event.

Grenfell and Jaakko Putkonen, a UW research associate professor of Earth and space sciences, have found evidence of the 2003 rain-on-snow occurrence in passive satellite microwave imagery, which they believe could provide a signature to help detect such events anywhere. They detail their work in a paper to be published March 25 in Water Resources Research, a journal of the American Geophysical Union.

Their methods could provide native people, whose livelihood depends on hoofed animals such as musk oxen, reindeer and caribou with a realistic chance of getting food to the herds to prevent mass starvation.

"We are talking about Banks Island, but this applies to the whole Arctic – Alaska, northern Canada, Siberia, Scandinavia – wherever there is permafrost," Putkonen said.