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CU-Boulder professor and Western Slope make snow-depth data public info

Artist concept of GPS Block 11-F satellite in orbit around Earth.
Artist concept of GPS Block 11-F satellite in orbit around Earth. Wikimedia Commons

CU-Boulder aerospace engineering sciences Professor Kristine Larson developed a clever method of using GPS (Global Positioning System) signals to measure snow depth.

In 2009, Larson and her colleagues discovered that the GPS signals that fail to hit a receiver and bounce off the Earth's surface could be used to measure snow depth, soil moisture and vegetation moisture.

Larson also pioneered the method of using GPS to chart minute plate tectonic and volcanic movements over time, worldwide.

The Mesa County Surveyor's Office in Grand Junction, Colo., has an intricate network of 23 stationary GPS reference stations, or receivers, both in and around Mesa County. Larson, in January, contacted the Mesa County Surveyor's Office with the intent to help the public.

In a CU-Boulder press release, Larson said, " I knew that most surveyors use the exact same equipment I do, and I looked at this as a chance to help out water managers, farmers and others on the Western Slope interested in information like spring runoff and crop moisture. I'm certainly not the only one measuring snow depth in Colorado, but now we have some free extra data that can help experts not only assess potential flooding events but also anticipate possible water restrictions in years of low moisture."

Originally developed in the 1970's for the military, GPS operates today by gathering signals simultaneously from 31 operating, orbital satellites.

The current GPS system in Mesa County is accurate to less than one centimeter- the width of a dime - over several hundred miles.

Mesa County Public Works Department surveyor Frank Kochevar, the administrator for the county's Real Time GPS Network (a network of over 28,000 square miles), was immediately interested in the project.

Kochevar said in a press release, " When Kristine contacted me to see if I would make our GPS data available to her, it was a no-brainer. I'm always interested in new ways to use this technology."

Larson needed the signal strength data that had not hit a receiver before bouncing off the snow. It is a bit of data that GPS surveyors and engineers are able to ignore.

It took Kochevar only minutes to change the logging strategy of the Mesa County GPS System, thereby, making it available to Larson on a daily basis.

Larson said, "The people in Mesa County have been nothing but good to me. And we both put our data our there for the public good, so people can better do their jobs."

Larson posts the snow depth data daily from about 10 Mesa County Stations.

Federal government groups that are utilizing Larsons public snow-depth data include meteorologists and climate scientists from the NOAA (National Oceanic and Atmospheric Administration), NCAR (National Center for Atmospheric Research) in Boulder and NASA.

Kochevar believes the data is of value to local and state government agencies that deal with water storage, in particular, the Colorado and Gunnison basins.

Larason also works with data obtained by UNAVCO, a National Science Foundation and NASA-sponsered facility in Boulder. The EarthScope Plate Boundary Observatory (PBO) is operated by UNAVCO. PBO is a network of approximately 1,100 GPS receivers in the western United States.

UNAVCO monitors constant motion of the colliding Pacific and North American tectonic plates using seismometers and strain meters. UNAVCO instruments are in place along the San Andreas Fault in California as well as in Yellowstone National Park that lies between Wyonimg and Montana. The equipment in Yellowstone, however, not only calculates daily snow depth and vegetation and soil changes, but also calculates "ground inflation" caused by magma moving within the Yellowstone volcanic system.

Last year, Larson developed a method for measuring the density of volcanic plumes using GPS.

"This is my baby, " Kochevar said. " I live for this network."

To view the map of the Mesa County GPS network, go to http://emap.mesacounty.us/GPS_Survey/GPS_Survey.htm

credit: CU-Boulder press release