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United States Department of Agriculture

Agricultural Research Service

Research Project: Soil Moisture Active Passive (Smap) in Situ Sensor Testbed

Location: Hydrology and Remote Sensing Laboratory

2012 Annual Report


1a.Objectives (from AD-416):
Work with Oklahoma State University (OSU) to evaluate the quality and accuracy of in situ soil moisture monitoring instrumentation in a rangeland field. Large scale sampling of soil moisture and co-location of a variety of soil moisture sensor technologies will be implemented in a rangeland field on OSU property under the management of their Range Research Station. Physical collection of soil moisture samples and characterization of the field on a routine basis for the term of this agreement will be the primary objective.


1b.Approach (from AD-416):
The cooperative work proposed here will assess the accuracy and representativeness of the soil moisture studies included in the project, based upon physical collection of soil moisture. This assessment will guide the NASA Soil Moisture Active Passive (SMAP) Science Definition Team in their calibration and validation activities for the satellite mission.

ARS will direct the research aspects of the project, leading the investigation and analysis of the results for incorporation into the SMAP Science Team Data Archive. Provide equipment and installation of in situ soil moisture sensors and assist in the collection of physical samples for calibration and validation of the sensors installed in the testbed.

OSU will be providing local logistical support for the project including field site maintenance and communications support for the instrumentation. Also administer a gravimetric and vegetation sampling regimen on a regular basis for calibration and validation of the sensor estimates with the support personnel funded by this agreement.


3.Progress Report:

In support of USDA ARS, Soil Moisture Active/Passive validation activities in central Oklahoma, scientists at the Oklahoma State University (OSU) installed an in situ sensor test bed in coordination with USDA ARS HRSL. The location is managed by OSU as a part of their rangeland management research station. OSU has collected soil texture and moisture information on a regular basis as a validation of the in situ sensor. In addition, they have conducted vegetation sampling protocols for the purpose of quality controling for some of the larger scale sensors which have vegetation dependence.

Data from four base stations can be downloaded via cellular technology, but OSU is maintaining and downloading data from several other satellite stations which have larger data production rates and cannot be easily transferred via cellular networks. Many of the sensors required a settling time before the data could be considered accurate. A rigorous sensor calibration experiment will be conducted in the summer of 2012 to reduce errors in soil moisture estimation for each of the in situ sensors.

A portion of the field was burned in the winter of 2012 as part of another research project, which will provide a vegetation free reference for the study region. A flux system was installed to monitor evapotranspiration at the site. An additional Distributed Temperature Sensing System was installed at the site in May of 2012. Also in May, a Spring Workshop was held to determine the status of the testbed and discuss future plans. The NASA Airborne Microwave Observatory of Subcanopy and Subsurface project (AirMOSS) project will be using the site as a validation testbed in the summer of 2012 and 2013.


Last Modified: 4/19/2014
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