Data Set ID:
SV12SRA

SMAPVEX12 Surface Roughness Data for Agricultural Area, Version 1

This data set contains surface roughness data collected at several agricultural 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):
  • TOPOGRAPHY > SURFACE ROUGHNESS
Data Format(s):
  • ASCII Text
Spatial Coverage:
N: 49.96, 
S: 49.44, 
E: -97.85, 
W: -98.51
Platform(s):GROUND-BASED OBSERVATIONS
Spatial Resolution:
  • 1 m x 1 m
Sensor(s):CAMERAS
Temporal Coverage:
  • 7 June 2012 to 19 July 2012
Version(s):V1
Temporal ResolutionVariesMetadata XML:View Metadata Record
Data Contributor(s):McNairn, H., J. Powers, and G. Wiseman.

Geographic Coverage

Other Access Options

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.

McNairn, H., J. Powers, and G. Wiseman. 2014. SMAPVEX12 Surface Roughness Data for Agricultural 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/QB4JHGKXH16O. [Date Accessed].
Created: 
28 February 2020
Last modified: 
28 February 2020

Data Description

This data set contains surface roughness data collected at several agricultural sites as a part of the Soil Moisture Active Passive Validation Experiment 2012 (SMAPVEX12). Measurements were taken at two locations within each SMAPVEX12 field site in the look directions of three Synthetic Aperture Radar (SAR) sensors: RADARSAT-2 (descending mode), UAVSAR, and PALS.

Parameter

Parameters in this data set include surface height variation, represented by the root mean square (RMS) in centimeters, and surface correlation length, also given in centimeters. Valid ranges for height variation are 0 - 3 cm and for correlation length are 0 - 30 cm.

File Information

Format and File Contents

Data are provided in the ASCII text files. 
SV12SRA_Soil_Roughness_ver4.txt contains the surface roughness data.
Field_Sites_ver4_coords.txt contains the UTM coordinates for the sampling points.

Table 1 describes the sampling data columns of the data file, while Table 2 describes the columns of the geolocation file.

Table 1. Data Fields and Descriptions for SV12SRA_Soil_Roughness_ver4.txt
Column Heading Description
OBJECTID ID of the sample
Site_ID ID of the field and the sample point within the field
UAV_Height Surface height variation (RMS) in the look direction of UAVSAR
UAV_Cor_L Surface correlation length in the look direction of UAVSAR
PALS_Height Surface height variation (RMS) in the look direction of PALS
PALS_Cor_L Surface correlation length in the look direction of PALS
R2_Height Surface height variation (RMS) in the look direction of RADARSAT2
R2_Cor_L Surface correlation length in the look direction of RADARSAT2
Table 2. Data Column Descriptions for Field_Sites_ver4_coords.txt
Column Heading Description
OBJECTID ID of the data record
Site_ID ID of the field and the sample point within the field
X UTM easting coordinate (meters)
Y UTM northing coordinate (meters)

Spatial Information

Coverage

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

Resolution

A one-meter grid board was used for in situ measurements.

Geolocation

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

Temporal Information

Coverage and Resolution

Photographs were acquired at each site one time from 07 June through 19 July 2012.

Software and Tools

No special tools are required to read these data. Any text editor or Web browser will display the ASCII text files.

Data Acquisition and Processing

Acquisition

Surface roughness was measured using a digital camera and a 1-m long pin profilometer consisting of 200 needles spaced from an interval of 5 mm. Three end-to-end images were captured to create a 3-m profile. For each SAR sensor and at each location, the photographs of the three separate profiles were joined into a single profile using a MATLAB application, post data collection, to provide the two roughness parameters: the standard deviation of surface heights (or the RMS heights) and the correlation lengths.

UAVSAR Angle = 226
PALS Angle = 180
RADARSAT2 Angle = 282

NULL values in the table are due to their bad quality, few pictures were not processed or the software fails to estimate the correlation length.

See more details in sections 1.1 and 2.1.2 of the SMAPVEX12 Database Report, released 18 December 2012.

Error Sources

Human error in placing the measurement equipment in the field for the measurements. See more details in sections 2.1.2 of the SMAPVEX12 Database Report, released 18 December 2012.

Quality Assessment

The roughness parameters are probably the most unreliable parameter in the process of soil moisture retrieval using microwave remote sensing. The first problem is that the scattering characteristics of natural surfaces are very complex and are still not completely understood; this makes validation of measured roughness parameters very difficult.

The quality of the data corresponds to the quality of the roughness measurements carried out in similar soil moisture field experiments. See more details in sections 2.1.2 of the SMAPVEX12 Database Report, released 18 December 2012.

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. 2013In Review. The Soil Moisture Active Passive Validation Experiment 2012 (SMAPVEX12): Pre-Launch Calibration and Validation of the SMAP Satellite. IEEE Trans. Geosci. Rem. Sens.

Contacts

Heather McNairn
Science and Technology Branch
Agriculture and Agri-Food Canada
960 Carling Avenue 
Ottawa, Ontario K1A 0C6 Canada 
e-mail: Heather.McNairn@agr.gc.ca
phone: +1 613-759-1815

Jarrett Powers
Science and Technology Branch
Agriculture and Agri-Food Canada
200-303 Main Street
Winnipeg, Manitoba R3C 3G7 Canada
e-mail: jarrett.powers@agr.gc.ca
phone: +1 204.259.4006

Grant Wiseman
Science and Technology Branch
Agriculture and Agri-Food Canada
200-303 Main Street
Winnipeg, Manitoba R3C 3G7 Canada
e-mail: grant.wiseman@agr.gc.ca
phone: +1 204.259.4006

Acknowledgments

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

Document Information

DOCUMENT CREATION DATE

October 2013

DOCUMENT REVISION DATE

February 2020

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