Data Set ID:
SV12PSMF

SMAPVEX12 Probe-Based In Situ Soil Moisture Data for Forest Area, Version 1

This data set contains in situ soil moisture data collected at several forested sites as a part of the Soil Moisture Active Passive Validation Experiment 2012 (SMAPVEX12).

This is the most recent version of these data.

Version Summary:

Initial release

STANDARD Level of Service

Data: Data integrity and usability verified

Documentation: Key metadata and user guide available

User Support: Assistance with data access and usage; guidance on use of data in tools

See All Level of Service Details

Parameter(s):
  • SOILS > SOIL DEPTH
  • SOILS > SOIL MOISTURE/WATER CONTENT > SOIL MOISTURE
  • SOILS > SOIL TEMPERATURE
Data Format(s):
  • Microsoft Excel
Spatial Coverage:
N: 49.96, 
S: 49.44, 
E: -97.85, 
W: -98.51
Platform(s):FIELD SURVEYS
Spatial Resolution:
  • 100 m x 100 m
Sensor(s):SOIL MOISTURE PROBE, SOIL TEMPERATURE PROBE
Temporal Coverage:
  • 7 June 2012 to 13 July 2012
Version(s):V1
Temporal Resolution1 day to 8 daysMetadata XML:View Metadata Record
Data Contributor(s):Mahta Moghaddam, Aaron Berg

Geographic Coverage

Other Access Options

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As a condition of using these data, you must cite the use of this data set using the following citation. For more information, see our Use and Copyright Web page.

Moghaddam, M. and A. Berg. 2014. SMAPVEX12 Probe-Based In Situ Soil Moisture Data for Forest Area, Version 1. [Indicate subset used]. Boulder, Colorado USA. NASA National Snow and Ice Data Center Distributed Active Archive Center. doi: https://doi.org/10.5067/2ETTBINRTSKX. [Date Accessed].
Created: 
27 February 2020
Last modified: 
28 February 2020

Data Description

This data set contains in situ soil moisture data collected at several forested sites as a part of the Soil Moisture Active Passive Validation Experiment 2012 (SMAPVEX12).

Parameters

Parameters in this data set include volumetric soil moisture, and both the real and imaginary part of the dielectric constant. Table 1 describes the units of measurement and sources of each parameter.

Table 1. Parameter Units and Sensors

Parameter

Unit of Measurement

Sensor

Valid range

Volumetric soil moisture Water Fraction Volume (m3/m3) Hydra Probe II 0 - 0.6 m3/m3  
Soil temperature degrees Celsius Thermometer 0 - 30°C 
Dielectric constant (real and imaginary part) Unitless Hydra Probe II 0 - 110
Depth of the organic layer Inch Measuring Stick 0 - 30 in

File Information

Format and File Contents

Data are provided in a single Microsoft Excel file containing one worksheet per site: F1, F2, F3, F5. Table 2 describes the soil sampling data columns of the data file, SV12PSMF_SMAPVEX_SoilDATA_final_03142013.xlsx.

Table 2. Data Fields and Descriptions

Column Heading

Description

DATE Date of the samples
SITE ID ID of the forest site (F1, F2, F3 or F5)
LOC ID ID of the sample location
LAT Latitude of the sampling location
LON Longitude of the sampling location
SOIL D1 Depth of the organic layer in inches: corner 1
SOIL D2 Depth of the organic layer: corner 2
SOIL D3 Depth of the organic layer: corner 3
SOIL D4 Depth of the organic layer: corner 4
SM1 Volumetric soil moisture: sample 1
SM2 Volumetric soil moisture: sample 2
SM3 Volumetric soil moisture: sample 3
Probe Type Type of the soil moisture probe (Hydra or Theta Probe)
T0 Surface temperature measurement in degrees Celsius
T5 Temperature measurement at 5 cm depth in degrees Celsius
T10 Temperature measurement at 10 cm depth in degrees Celsius
EPS REAL1 Real part of dielectric constant for the soil moisture sample 1
EPS IMAG1 Imaginary part of dielectric constant for the soil moisture sample 1
EPS REAL2 Real part of dielectric constant for the soil moisture sample 2
EPS IMAG2 Imaginary part of dielectric constant for the soil moisture sample 2
EPS REAL3 Real part of dielectric constant for the soil moisture sample 3
EPS IMAG3 Imaginary part of dielectric constant for the soil moisture sample 3

Missing data are represented by a blank [ ] or by NaN.

Spatial Information

Coverage

Southernmost Latitude: 49.44°N
Northernmost Latitude: 49.96°N
Westernmost Longitude: 98.51°W
Easternmost Longitude: 97.85°W

Resolution

For each site, sampling was performed on two orthogonal transects within a circle of approximately 100 m radius.

Projection

Data are provided in Universal Transverse Mercator (UTM), Zone 14 N, World Geodetic System 1984 (WGS84) coordinates.

Temporal Information

Coverage and Resolution

Measurements were taken every one to eight days from 07 June 2012 through 13 July 2012.

Software and Tools

No special tools are required to view these data. A spreadsheet program such as Microsoft Excel is recommended.

Data Acquisition and Processing

Acquisition

Section Sampling

The soil and vegetation sampling approaches used for the agriculture cropland and forest sites was different, due to the inherent differences in the characteristics of these landscapes, the measurement strategies for forests and crops, and the ease of access to the sites.

One sample site was located in each of the four forest sites (Figure 1) and was chosen to be representative of the heterogeneity of the site. The observation area for both soil moisture and vegetation sampling within each site consisted of two orthogonal transects within a circle of 100 m radius (Figure 2). Each of the nine sampling points was spaced 50 m apart. Points were flagged and their GPS coordinates were determined at the beginning of the campaign to facilitate navigation back to each point. At each sampling point, organic soil thickness was determined at four corners of a 10 inch quadrant (Figure 3).

Map of Forest Study Sites
Figure 1. Map of Forest Study Sites (Site ID F1, F2, F3, F5)

Sample Locations
Figure 2. Schematic diagram of sample locations (Location ID) within the forest sites.

Site Soil Sampling
Figure 3. Organic soil thickness was determined at four corners of a 10 inch quadrant.

See more details in section 2.1.1 of the SMAPVEX12 Database Report, released 18 December 2012.

Instrumentation

Investigators used the Stevens Hydra Probe II to measure surface volumetric soil moisture.

Hydra Probes

Hydra Probes are based on coaxial impedance dielectric reflectometry. The probes were connected to a PDA. They use an oscillator to generate an electromagnetic signal at 50 MHz that is propagated through three metal tines into the soil. The part of the signal that is reflected back to the unit is measured in volts and is used to numerically solve Maxwell's equations, to calculate the impedance and the real and imaginary dielectric permittivity.

Processing Steps

Calibration of the Probe Measurements

Similar to the agricultural fields a unique calibration curve (R2=.798, p<0.05, n=37) was developed between the volumetric cores obtained from the forest sites and the Steven's Hydra Probe soil moisture measurements obtained at the same location. Points which fell outside 1.5 times the standard deviation of the difference between the core and the probe measured soil moisture were determined to be outliers and removed from the data set. A leave-one-out validation was conducted (Rowlandson et al. 2013) and indicated that the calibration equation was robust. The RMSE of the developed equation was .058 m3m-3, a RMSE greater than that determined in agricultural fields. It is anticipated that the higher RMSE was due to the complications of obtaining soil samples (and probe readings) over these sites due the amount of litter material in the soils.

Error Sources

The RMSE of the developed calibration equation was .058 m3m-3, a RMSE greater than that determined in agricultural fields. It is anticipated that the higher RMSE was due to the complications of obtaining soil samples (and probe readings) over these sites due the amount of litter material in the soils.

References and Related Publications

McNairn, H., T. Jackson, G. Wiseman, S. Belair, A. Berg, P. Bullock, A. Colliander, M. Cosh, S. Kim, R. Magagi, M. Moghaddam, J. Adams, S. Homayouni, E. Ojo, T. Rowlandson, J. Shang, K. Goita, and M. Hosseini. 2013, In Press. The Soil Moisture Active Passive Validation Experiment 2012 (SMAPVEX12): Pre-Launch Calibration and Validation of the SMAP Satellite. IEEE Trans. Geosci. Rem. Sens.

Rowlandson, T. L., A. A. Berg, P. R. Bullock, E. R. Ojo, H. McNairn, G. Wiseman, and M. H. Cosh. 2013, In Press. Evaluation of Several Calibration Procedures for a Portable Soil Moisture Sensor. Journal of Hydrology.

Contacts

Mahta Moghaddam
Department of Electrical Engineering
University of Southern California
3737 Watt Way
Los Angeles, CA 90089, USA
e-mail: mahta@usc.edu
phone: +1 213.740.4712

Aaron Berg
Department Geography
University of Guelph
Guelph, ON, N1G 2W1, Canada
e-mail: aberg@uoguelph.ca 
phone: +1 519.824-4120

Acknowledgments

Agriculture and Agri-Food Canada, National Aeronautics and Space Administration, U.S. Department of Agriculture, Environment Canada, University of Manitoba, University of Guelph, Massachusetts Institute of Technology (MIT), University of South Carolina, University of Colorado, University of Sherbrooke, Ohio State, University of Montana, Florida International University, University of Southern California, Texas A&M, Georgia Institute of Technology, University of Washington are acknowledged for their support for the campaign.

Field Sampling Team

Mariko Bürgin (University of Southern California)
Vanessa Escobar (NASA Goddard)
Alexandra Konings (MIT)
Parag Narvekar (MIT)
Stacie Westervelt (University of Winnipeg)
Kaighin McColl (MIT)
Alan Rich (University of Winnipeg)
Jennifer Watts (University of Montana)
Hoda Jafarian (University of Sherbrooke)
Matt Jones (University of Montana)
Mehdi Hosseini (University of Sherbrooke)
Dominik Schneider (University of Colorado)
Karel Janik (University of Sherbrooke)
Maheshwari Neelam (Texas A&M)
Steven Chan (NASA JPL)
Ramata Magagi (University of Sherbrooke)
Maria Abrahamowicz (Environ. Canada)
Mike Cosh (USDA)
Najib Djamai (University of Sherbrooke)

Document Information

DOCUMENT CREATION DATE

October 2013

DOCUMENT REVISION DATE

February 2020

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