NASA plane measures sea ice snow

SIKU CIRCUMPOLAR NEWS SERVICE

A radar-equipped NASA plane flew over the Arctic last week to measure snow on top of sea ice, because any reduction in snow cover could spell disaster for marine mammals and also speed up global warming.

Polar bears raise their young in snow dens sitting atop sea ice, so the depth of that snow is critical to their survival, Thorsten Markus of NASA’s Goddard Space Flight Centre outside Washington told Reuters. The temperature under a layer of snow rarely falls below freezing, so polar bears often let snow drift around their bodies to form an insulating layer of warmth. Without enough snow on the sea ice, polar bears can’t even build their dens.

The snow depth on the sea ice is also an important factor in the polar climate. That’s because snow on sea ice acts like “a thick quilt on top of a thin blanket,” slowing the transfer of heat to the frigid air from the warmer water.

“If the snow depth changes, it will have profound implications” on the way the water’s relative warmth is transferred to the polar atmosphere, Markus told Reuters. “So it’s really, really important.”

NASA’s Aqua satellite has an instrument called an “Advanced Microwave Scanning Radiometer” that is used to measure snow depth.

NASAs flights over the sea ice are intended to confirm these satellite observations. Flying at just 150 metres, the special plane carries instruments that bounce signals off the top and the bottom of the snow, which should give scientists an accurate idea of how deep the snow is.