Snow Pits and Cookie Cutters

2/7/2012 4:10:50 PM

Snow Pits and Cookie Cutters

Sunrise over the tundra

Blue horizon, pink skies, and white snow: the components of an Arctic sunrise greet us in splendor this morning. We spend another day on the Tucker tracked vehicle, this time on Foggy Island. After hours of scanning the coastline for a definitive den signal, we have no such luck, just find other hot spots suggesting possible dens that the team will recheck in March with the dogs. It's so wonderful to ride and think that maybe just beneath the snow in front of you there's a mother polar bear with her cubs all snug and warm.

Tucker vehicle

We stop the Tucker to let Dr. Glen Liston, the snow scientist, do his work. He chooses a snowdrift that had been a denning spot in previous years—but isn't currently in use—to dig a snow pit. He studies the layers of snow for time of deposition, hardness, snow crystal size, and density (mass per unit volume).

Dr. Glen Liston in snow pit

Glen samples a standard volume of snow by using a stainless steel cookie cutter of exactly 100 cubic centimeters. He then uses an electronic scale to calculate the snow's mass. Interestingly, density changes in snow layers over time depending on temperature differences and wind erosion and deposition.

Dr. Liston takes a snow sample

It's important to understand snow density in relation to polar bear dens because it can have an effect on the gas exchange that takes place within the den. The density can also affect the thermal heat loss from the polar bears in the den. Learning more about the snow density of previous dens can help us generate maps of snowdrifts where polar bears are likely to den.

Temperature: -22F

Wind speed: 8 mph

Photos courtesy of April Cheuvront.

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