Featured Research

from universities, journals, and other organizations

New method to measure snow, vegetation moisture with GPS may benefit farmers, meteorologists

Date:
November 23, 2009
Source:
University of Colorado at Boulder
Summary:
Scientists have 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.

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.

Related Articles


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, said 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, Colo. just south of Boulder, which was hit by two large snowstorms over a three-week span in March and April of 2009. Published in the September issue of Geophysical Research Letters, 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.

The new study on snow and vegetation moisture will be presented at the fall meeting of the American Geophysical Union being held in San Francisco Dec. 14 to 18.

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.

Study collaborators, all from Boulder, include CU-Boulder's Eric Small and Mark Williams, John Braun from the University Corporation for Atmospheric Research, Ethan Gutmann from the National Center for Atmospheric Research and Valery Zavorotny and Andria Bilich from National Oceanic and Atmospheric Administration.

The most recent effort by the team has been conducted in cooperation with Munson Farms of Boulder. The new experiment is designed to analyze how the GPS signals traveling through alfalfa, corn and grass correlate with the amount of water in the vegetation. Small and CU-Boulder students have been cutting and weighing both wet and dry vegetation and matching the sample weights with comparative GPS multipath signal changes using a receiver set up at the farm.

The team is collaborating with Bob Munson, owner of Munson Farms and a former antenna engineer at Ball Aerospace & Technologies of Boulder. Munson holds more than 30 patents related to antenna design, including one of the most widely used antennas for GPS applications like vehicle navigation and recreational applications.

"With this system, the GPS antenna allows us to see across a whole field, unlike individual moisture sensors that are sometimes set up to measure only small, specific areas," Munson said. If a farmer relied on data from only a single soil moisture sensor that happened to be in a particularly dry pocket of his crop field, for example, it could have a negative effect on the timing and quality of the harvest, he said.

Originally developed in the 1970s for military use, GPS technology is in wide use today, telling drivers and hikers their exact position on the planet and providing directions to their destinations by gathering at least four signals simultaneously from the 31 GPS satellites now orbiting Earth.

Braun, who received his doctorate from CU-Boulder in 2004, also is interested in observing water vapor in the atmosphere by measuring the delay of GPS signals as they propagate through the atmosphere. "Water scarcity is going to be a problem for the western United States in the coming century," he said. "Having improved observations of water in all of its phases is going to be an important step as we monitor changes in the environment, which is the most intriguing part of this project for me."

Larson helped to pioneer the use of GPS as a tool to measure the movement of tectonic plates and the crustal deformation associated with earthquakes as a graduate student at the University of California-San Diego in 1980s. "Even then we knew that the data were corrupted by ground reflection, which was really irritating," she said. "But it was only recently that we began to think maybe there was a way to use these ground reflections to our benefit."

All of the team's research efforts revolve around the water cycle, said Larson. "We want to know if the water is in the ground, in the snow or in the vegetation, and how much is evaporating into the atmosphere, since it will ultimately be returned to the Earth's surface through precipitation events."


Story Source:

The above story is based on materials provided by University of Colorado at Boulder. Note: Materials may be edited for content and length.


Cite This Page:

University of Colorado at Boulder. "New method to measure snow, vegetation moisture with GPS may benefit farmers, meteorologists." ScienceDaily. ScienceDaily, 23 November 2009. <www.sciencedaily.com/releases/2009/11/091120135212.htm>.
University of Colorado at Boulder. (2009, November 23). New method to measure snow, vegetation moisture with GPS may benefit farmers, meteorologists. ScienceDaily. Retrieved October 24, 2014 from www.sciencedaily.com/releases/2009/11/091120135212.htm
University of Colorado at Boulder. "New method to measure snow, vegetation moisture with GPS may benefit farmers, meteorologists." ScienceDaily. www.sciencedaily.com/releases/2009/11/091120135212.htm (accessed October 24, 2014).

Share This



More Earth & Climate News

Friday, October 24, 2014

Featured Research

from universities, journals, and other organizations


Featured Videos

from AP, Reuters, AFP, and other news services

EU Gets Climate Deal, UK PM Gets Knock

EU Gets Climate Deal, UK PM Gets Knock

Reuters - Business Video Online (Oct. 24, 2014) EU leaders achieve a show of unity by striking a compromise deal on carbon emissions. But David Cameron's bid to push back EU budget contributions gets a slap in the face as the European Commission demands an extra 2bn euros. David Pollard reports. Video provided by Reuters
Powered by NewsLook.com
Deep Sea 'mushroom' Could Be Early Branch on Tree of Life

Deep Sea 'mushroom' Could Be Early Branch on Tree of Life

Reuters - Innovations Video Online (Oct. 24, 2014) Miniature deep sea animals discovered off the Australian coast almost three decades ago are puzzling scientists, who say the organisms have proved impossible to categorise. Academics at the Natural History of Denmark have appealed to the world scientific community for help, saying that further information on Dendrogramma enigmatica and Dendrogramma discoides could answer key evolutionary questions. Jim Drury has more. Video provided by Reuters
Powered by NewsLook.com
Raw: Tornado Rips Roofs in Washington State

Raw: Tornado Rips Roofs in Washington State

AP (Oct. 24, 2014) A rare tornado ripped roofs off buildings, uprooted trees and shattered windows Thursday afternoon in the southwest Washington city of Longview, but there were no reports of injuries. (Oct. 24) Video provided by AP
Powered by NewsLook.com
Fast-Moving Lava Headed For Town On Hawaii's Big Island

Fast-Moving Lava Headed For Town On Hawaii's Big Island

Newsy (Oct. 24, 2014) Lava from the Kilauea volcano on Hawaii's Big Island has accelerated as it travels toward a town called Pahoa. Video provided by Newsy
Powered by NewsLook.com

Search ScienceDaily

Number of stories in archives: 140,361

Find with keyword(s):
Enter a keyword or phrase to search ScienceDaily for related topics and research stories.

Save/Print:
Share:

Breaking News:

Strange & Offbeat Stories


Plants & Animals

Earth & Climate

Fossils & Ruins

In Other News

... from NewsDaily.com

Science News

Health News

Environment News

Technology News



Save/Print:
Share:

Free Subscriptions


Get the latest science news with ScienceDaily's free email newsletters, updated daily and weekly. Or view hourly updated newsfeeds in your RSS reader:

Get Social & Mobile


Keep up to date with the latest news from ScienceDaily via social networks and mobile apps:

Have Feedback?


Tell us what you think of ScienceDaily -- we welcome both positive and negative comments. Have any problems using the site? Questions?
Mobile: iPhone Android Web
Follow: Facebook Twitter Google+
Subscribe: RSS Feeds Email Newsletters
Latest Headlines Health & Medicine Mind & Brain Space & Time Matter & Energy Computers & Math Plants & Animals Earth & Climate Fossils & Ruins