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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).

Geographic Coverage

Parameter(s):
  • Topography > Surface Roughness > Correlation Length
  • Topography > Surface Roughness > RMS of Surface Height Variation
Spatial Coverage:
  • N: 49.96, S: 49.44, E: -97.85, W: -98.51

Spatial Resolution:
  • 1 m x 1 m
Temporal Coverage:
  • 7 June 2012 to 19 July 2012
Temporal Resolution: Varies
Data Format(s):
  • ASCII Text
Platform(s) GROUND-BASED OBSERVATIONS
Sensor(s): CAMERAS
Version: V1
Data Contributor(s): McNairn, H., J. Powers, and G. Wiseman.
Data Citation

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: http://dx.doi.org/10.5067/QB4JHGKXH16O. [Date Accessed].

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Notice: 

The documentation for this data set was provided solely by the Principal Investigator(s), and was not further developed, thoroughly reviewed, or edited by NSIDC. Thus, support for this data set may be limited.

Detailed 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).

Format

Data are provided in the ASCII tab-delimited text files. The following tables describe the column headings and contents in the files.

Table 1. Data Column Descriptions for SV12SRA_Soil_Roughness_ver4.csv
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 X coordinate
Y UTM Y coordinate
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File and Directory Structure

Data files are available on the HTTPS site in the https://n5eil01u.ecs.nsidc.org/SMAP_VAL/SV12SRA.001/ directory.

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File Naming Convention

SV12SRA_Soil_Roughness_ver4.txt contains the surface roughness data.

Field_Sites_ver4_coords.txt contains the UTM coordinates for the sampling points

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File Size

Together the data files are approximately 34 KB.

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Spatial Coverage

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

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Spatial Resolution

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

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Temporal Coverage and Resolution

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

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Parameter or Variable

Parameters include root mean square (rms) of surface height variation (cm), and correlation length (cm).

Parameter Range

Valid parameter values are as follows: 
Root mean square of surface height variation: 0 - 3 cm
Correlation length: 0 - 30 cm

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Software and Tools

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

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Data Acquisition and Processing

This data file contains soil roughness measurements taken at two locations within each SMAPVEX12 field in the look directions of RADARSAT-2 (descending mode), UAVSAR, and PALS. 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.

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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.

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References and Related Publications

Contacts and Acknowledgments

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

N/A

No technical references available for this data set.
No FAQs or How Tos available for this data set.

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