For avalanche forecasters, up-to-date data about the snowpack are as vital as the temperature and the weather, but harder to obtain. Whereas high-tech weather stations can be run automatically, snowpack monitoring requires considerable low-tech and difficult fieldwork. Every day, experts from avalanche centers monitor the snowpack surface in different areas and dig tens of snow pits, the only way to view cross sections of the snowpack and its various layers. Workers check the size and shape of grains in each snow pit and test the stability of the snow. Bad weather and risk of avalanche often hamper fieldwork. Scientists are thus looking for new ways to obtain real-time information about the snow that will make avalanche forecasting safer, easier and more precise.
A fresh look from above
A May morning of ¿12¿C is pretty warm if you are at the Ny ¿lesund arctic research base in the Svalbard Islands, a one-hour flight from the North Pole. In the flat, icy desert surrounding the research base, Mauro Valt is digging a snowpit. In a matter of minutes, he¿s down in the pit to the shoulders, scraping some snow from the layers and scrutinizing the flakes with a magnifier. Meanwhile a group of scientists from the Italian National Research Council (CNR) unwrap light sensors and laptops. There is no risk of avalanche in this locale. Instead what brought the Italian team to the arctic is the goal of enlisting satellite technologies in the fight against avalanches. "The arctic environment is an ideal open lab for our tests because it has huge snowy flats, no pollution and during summer the sunlight is round-the-clock," says Rosamaria Salvatori, who leads the Italian team.
Before leaving the base camp, the researchers downloaded fresh satellite images of the area that reveal precisely how much sunlight the snow currently reflects. "The amount of reflected light depends on the snow¿s thickness, the content of water and on the type of crystals that it contains," Salvatori explains. Over the course of years of fieldwork, investigators have been correlating the satellite data with the type of snow found on the ground. They have discovered, for example, that the patterns of reflection in the infrared spectrum differ among fresh, wet or refrozen snow. Crystals that are star-shaped or that have been remodeled by the wind also reflect light differently. "To a certain extent, we can now guess from the satellite data which type of snow is on the ground," Salvatori reports. Even if satellites can see only the upper four to five centimeters of the snowpack, they can tell whether lots of fresh snow has just fallen over an area, or indicate the presence of superficial hoar--two conditions that increase avalanche danger. The Italian team hopes that one day avalanche centers could use satellites to monitor remote areas in real time, limiting fieldwork. Another team at the University of Colorado in Boulder is working independently on snow satellite sensing, with similar results.
More research is needed before these systems can be applied to avalanche forecast, however. "It will need a lot of tuning up before we can transfer the results we obtained in the arctic to the mountains, where we have to take into account slopes, pollution, rough terrain, vegetation and shadows," Salvatori cautions. Nevertheless, researchers are optimistic. "Satellites will not stop us completely from digging snow pits," Valt remarks, "but we are confident that they may ease our daily routine and risk and provide a more precise forecast of avalanches."
Sergio Pistoi (www.sergiopistoi.com) is a freelance science and medical journalist based in Rome, Italy. In May 2003 he traveled to the Ny ¿lesund research base at the Svalbards with a grant from the Italian Association of Science Writers UGIS.