Color of snowpack
SNARL lecture unveils new avalanche studies
Avalanche. If you live in snow-covered climes, the very word can bring a shudder, much the same as “tornado” in the Midwest and “earthquake” in the West. Like those other natural events, progress is being made in the study of how they occur, but much is still being discovered and debated.
Ned Bair, a Mammoth Mountain Ski Patroller, is a resident expert in avalanches, a topic that’s captured his professional interest. It’s a major facet of his ongoing environmental grad studies at UC Santa Barbara, and part of his ancillary work with the Army Corps of Engineers. Bair presented a talk on avalanches and a new technique being explored to study them as the first lecture of this year’s 8-part Sierra Nevada Aquatic Research Laboratory (SNARL) lecture series, which kicked off Tuesday night, April 27.
Bair is currently experimenting with near-Infra Red (nIR) photography as a possible new tool for finding “deficit zones,” using the non-visible light spectrum to capture grain size based on the reflectance off the snowpack. “All snow is white to the eye … we don’t see the grain difference in the visible spectrum,” Bair said. “Snow is actually ‘colorful’ if you can ‘see’ it properly.”
The process involves taking nIR pictures of the inside of snow pit walls. After a short trip through Photoshop, the photos are uploaded into a program called MATLAB, which calibrates the images to a series of white and grey targets and then allows Bair to do grain size calculations. The result: an unusual “picture” of the snowpack. Bair said nIR is still in its experimental phase and not yet a useful application, revealing some interesting details, but not as much as he’d like to see. “It’s not definitive enough,” he said. Avalanches are complicated and the pictures are often hard to read. Bair suggested the process might need to be adjusted in terms of how pit walls are photographed and handled in Photoshop, etc.
European avalanche guru Werner Munter once posited, “There is too much spatial variation in snowpack for any test to be definitive.” Bair agrees with him, but nonetheless hopes nIR will provide another resource in the pursuit of dealing with avalanches and ideally reducing deaths from them one day to zero.
So far the 2009-10 U.S. ski season, has logged 32 avalanche-related fatalities (most due to trauma). The expectation is that 500 deaths will occur worldwide. Bair pointed out the domestic five-year average is 29, and that the number has been creeping up roughly 1 death every two years. Only recently has any data been collected on backcountry avalanche deaths, but some rough statistics are currently being formulated.
Professional ski patroller deaths, he added, run about one for every 5,278 patrollers. That figure puts them just between firefighters and police, relatively speaking, though all three are far below the most dangerous job: commercial fishermen, which average one death for every 600 on the job.
According to Bair’s figures, Mammoth Mountain has had an “above average” snow year — only eight others have been bigger since 1982. The Forest Service started monitoring snowfall in 1968 and the Ski Area took over in 1982. More skier days in recent years has meant better recording of both precipitation and avalanches. As of April 22, the Mountain has experienced about 500 avalanches, though most have been small Category 1 or 2 events, with 5 being the greatest.
Bair also dispelled a few myths during his talk. First, he said statistical data shows no relation between the amount of precipitation and the number of Category 5 events. He also said the popular, simplistic view held by many is that snowpack is uniform. It’s actually full of variables, he said.
Current methods of control range from simple ski cutting, to hand charges and, for ski areas that have access and funds for it, 105 mm Howitzer cannons. At $100 each for rounds, smaller ski areas may find this a bit cost-prohibitive, but on Mammoth it’s just another tool in the toolbox. In terms of analyzing avalanches, ski patrollers use hand-dug snow pits and record “lemons,” which are red flags or signs of instability in the snowpack. “You want to find out what is the spatial structure in the layering in the snowpack,” Bair said. “Lemons look at the snow’s grain size, type hardness and slab depth.”
The problem: pits don’t give a very broad view of an avalanche slope. You have to dig more than one, and even several may not tell the whole story. Compression tests help, but even then, “you can pound on new snow, but it doesn’t mean you’re going to set off an avalanche,” Bair told the audience.
SNARL lectures run for the next seven consecutive Tuesdays at 7 p.m. in the Green Church off U.S. 395 near the Mammoth Airport. Lectures last about an hour and are free, but start on time, so don’t be late. You don’t want to miss a moment. Check our Calendar section for upcoming topics.
