New method to measure snow, soil moisture with GPS may benefit climate modelers

Washington, November 21 (ANI): A research team led by the University of Colorado at Boulder has found a clever way to use traditional GPS satellite signals to measure snow depth as well as soil and vegetation moisture, a technique expected to benefit meteorologists, water resource managers, climate modelers and farmers.

The researchers have developed a technique that uses interference patterns created when GPS signals that reflect off of the ground called "multipath" signals - are combined with signals that arrive at the antenna directly from the satellite, according to CU-Boulder aerospace engineering sciences Professor Kristine Larson, who is leading the study.

"Since such multipath signals arrive at GPS receivers "late," they have generally been viewed as noise by scientists and engineers and have largely been ignored," said Larson, who is leading a multi-institution research effort on the project.

In one recent demonstration, the team was able to correlate changes in the multipath signals to snow depth by using data collected at a field site in Marshall, Colorado just south of Boulder, which was hit by two large snowstorms over a three-week span in March and April of 2009.

The snowpack study built on a project Larson and her colleagues have been working on that is funded by the National Science Foundation to measure soil moisture using GPS receivers.

Larson's group is the first to use traditional GPS receivers, which were designed for use by surveyors and scientists to measure plate tectonics and geological processes, to assess snowpack, soil moisture and vegetation moisture.

The team hopes to apply the technique to data collected from an existing network of more than 1,000 GPS receivers in place around the West known as the Plate Boundary Observatory, a component of NSF's Earthscope science program.

"By using the Plate Boundary Observatory for double duty, so to speak, we hope this will be a relatively inexpensive and accurate method that can benefit climate modelers, atmospheric researchers and farmers throughout the West," said Larson. (ANI)