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Continental Scale Soil Moisture Network Expansion

  • Principal Investigators:
    John Braun, Kristine Larson
  • UNAVCO Engineers: Sarah Doelger, Emily Seider
  • Dates: April 4-6 2012
  • Location: Ames, Iowa
  • Funding Source: NSF

Written by Sarah Doelger


One continuously operating GPS station was installed In Ames, Iowa as part of the larger Continental Scale Soil Moisture monitoring network. Principal Investigators Kristine Larson and John Braun are using GPS signal-to-noise (SNR) data from these sites to estimate surface soil moisture content.

The GPS antenna is located on top of a three meter tall tri-tower which will allow a large footprint of the ground-reflected GPS signal to be seen. Also, in-situ ground moisture sensors and a meteorological package are co-located with the GPS equipment.


The equipment in Iowa is located in a soybean field. Other stations in the soil moisture network are placed in fields of differing vegetation types including corn, wheat, and grass. Each unique vegetation type will help identify how vegetation amount and structure affect GPS-derived estimates of soil moisture.

Braun and Larson hope that the algorithms developed for each vegetation type will be reliable enough to begin applying them at the many existing GPS stations around the United States.

The GPS data will also provide an independent means to validate the results of the NASA SMAP satellite mission.

Ongoing UNAVCO Involvement

UNAVCO has now been involved with the installation of nine different Soil Moisture GPS stations in Oklahoma and Colorado.
Past highlights:

Braun and Larson also use GPS SNR to measure Snow Water Equivalent and use data from UNAVCO constructed GPS stations in Utah and the Front Range of Colorado.
See: GPS as a snow sensor: Doc's Meadow installation »

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Last modified: 2020-02-03  20:49:07  America/Denver