US: Prototype devices that use light pulses, GPS satellite signals, and other technologies offer the potential to almost instantly measure large areas of snow. In time, such devices might even provide a global picture of snow depth, according to scientists at the National Center for Atmospheric Research (NCAR).
NCAR is conducting the research with several collaborating organisations, including the National Oceanic and Atmospheric Administration (NOAA) and the University of Colorado Boulder. The work is supported by NCAR”s sponsor, the National Science Foundation.
Transportation crews, water managers and others who make vital safety decisions need precise measurements of how snow depth varies across wide areas. But traditional measuring devices such as snow gauges or yardsticks often are inadequate for capturing snow totals that can vary even within a single field or neighbourhood.
The nation”s two largest volunteer efforts-The National Weather Service”s Cooperative Observer Program and the Community Collaborative Rain, Hail, and Snow Network (CoCoRaHS)-each involve thousands of participants nationwide using snow boards, but their reports are usually filed just once a day.
More recently, ultrasonic devices have been deployed in some of the world”s most wintry regions. Much like radar, these devices measure the length of time needed for a pulse of ultrasonic energy to bounce off the surface of the snow and return to the transmitter. However, the signal can be affected by shifting atmospheric conditions, including temperature, humidity, and winds.
The specialised laser instruments under development at NCAR can correct for such problems. Once set up at a location, they can automatically measure snow depth across large areas. Unlike ultrasonic instruments, lasers rely on light pulses that are not affected by atmospheric conditions.
New tests by the scientists indicated that a laser instrument installed high above treeline in the Rocky Mountains west of Boulder can measure 10 feet or more of snow with an accuracy as fine as half an inch or better. The instrument, in a little over an hour, measures snow at more than 1,000 points across an area almost the size of a football field to produce a three-dimensional image of the snowpack and its variations in depth.
One limitation for the lasers, however, is the light pulses cannot penetrate through objects such as trees and buildings. This could require development of networks of low-cost laser installations that would each record snow depths within a confined area. Alternatively, future satellites equipped with such lasers might be capable of mapping the entire world from above.
Source: GPS Daily