Location: Hydrology and Remote Sensing Laboratory
Title: Validating the BERMS in situ soil water content data record with a large scale temporary network Authors
Submitted to: Vadose Zone Journal
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: April 24, 2013
Publication Date: April 25, 2013
Repository URL: http://handle.nal.usda.gov/10113/59843
Citation: Cosh, M.H., Jackson, T.J., Smith, C., Toth, B., Berg, A. 2013. Validating the BERMS in situ soil water content data record with a large scale temporary network. Vadose Zone Journal. DOI: 10.2136/vzj2012.0151. Interpretive Summary: In situ soil moisture networks are expensive to operate for long periods of time with respect to maintenance and labor. These costs increase with the number of stations in the network, but more stations provide better accuracy. One method of reducing these costs is to determine how a few select in situ stations may be able to represent a large domain with better accuracy by using temporal stability analysis. If a network is shown to be temporally stable, consistent patterns of soil moisture are present throughout a time period. Given knowledge of this pattern, a few select stations can be scaled to the large domain with the same accuracy as a large network. An experiment was conducted in the boreal forests of Canada where a few permanent stations are deployed. A temporary network of 20 in situ soil moisture stations were installed for three months and a scaling relationship was established for the few permanent stations. This research will lead to a more efficient in situ network protocol scaling sparse stations while maintaining accuracy for scientific investigation.
Technical Abstract: Calibration and validation of soil moisture satellite products requires data records of large spatial and temporal extent and for diverse land cover types. Obtaining these data, especially for forests, can be challenging. These challenges can include the remoteness of the locations, and expense of equipment. A location with a long record of soil water content data and the potential provide this important data is the Boreal Ecosystem Research and Monitoring Sites (BERMS) to Saskatchewan Canada. In and around the BERMS study area, there are five long-term soil water content profile stations. These stations potentially provide a critical but incomplete view of the soil water content patterns across a study domain of 10,000 square kilometers, however, the representativeness of these observations for this purpose has not yet been evaluated. In coordination with the Canadian Experiment-Soil Moisture 2010 (CANEX-SM10), a temporary network of surface soil water content sensors was installed during the summer of 2010 to enhance the data resources of the BERMS network. During the 3-month deployment, 20 stations recorded surface soil water content which was then used as basis for up-scaling and validating the BERMS network and products from the Soil Moisture Ocean Salinity (SMOS) Satellite. This large domain is approximately 1200 square kilometers and provides a higher confidence because of the increased number of sampling sites. Using temporal stability analysis, this network verified that the BERMS network could be scaled to a satellite scale footprint with a root mean square error (RMSE) of 0.025 m3/m3, and applied to the entire period of record.