Tuesday, March 07, 2017

Planes, pits & snowmobiles: how scientists get good data

by Emily Benson

In the middle of a clearing, beneath the bright blue bowl of the western Colorado sky, two scientists stood chest-deep in a pit dug into the snow. Crisp morning sunlight glinted off the blocky metal trowel in Andrew Hedrick’s hand. Hedrick, a hydrology technician, stuck the instrument into the solid white wall before him, withdrew it — now loaded with snow — and delicately skimmed off the extra flecks. Amid the muffled whine of snowmobiles ferrying researchers and equipment around the field site, he weighed the snow, then emptied his trowel, ready for another sample. Researchers will use the information Hedrick collected to validate new ways to measure snow and calculate the density of the snowpack — which, together with its depth, indicates how much water it contains. A handful of other scientists, from agencies and universities across the globe, swirled around the clearing and among nearby spruce trees. The researchers measured the snow with poles and rulers, radar and microwave sensors, and even packed a cooler with snow samples destined for micro-CT scanning at a lab in New Hampshire. Overhead, sensors affixed to airplanes made similar measurements throughout the day. Snow delivers about 60 to 70 percent of the West’s water supply. The snowpack is an icy natural reservoir that swells throughout the winter, then melts during the summer, providing rivers, agricultural fields, and communities with water. But the amount of moisture in snow varies, and keeping track of how wet snow is across an entire landscape — information essential to the resource managers, farmers and scientists who forecast water supplies and flood potential — has proven difficult...more

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