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Data Set ID:
SV12SRF

SMAPVEX12 Surface Roughness Data for Forest Area, Version 1

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

Geographic Coverage

Spatial Coverage:
  • N: 49.96, S: 49.44, E: -97.85, W: -98.51

Spatial Resolution:
  • 1 m
  • 3 m
Temporal Coverage:
  • 7 June 2012 to 19 July 2012
Temporal Resolution: Not specified
Parameter(s):
  • Topography > Surface Roughness > RMS of Surface Height Variation
  • Topography > Surface Roughness > Surface Correlation Length
Platform(s) GROUND-BASED OBSERVATIONS
Sensor(s): CAMERAS
Data Format(s):
  • Microsoft Excel
Version: V1
Data Contributor(s): Ramata Magagi

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.

Magagi, R. 2014. SMAPVEX12 Surface Roughness Data for Forest 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/10.5067/0OCZDB099FWR. [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 forested sites as part of the Soil Moisture Active Passive Validation Experiment 2012 (SMAPVEX12).

Format

Data are provided in an Excel file.

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File and Directory Structure

Data are available on the FTP site in the ftp://n5eil01u.ecs.nsidc.org/SAN/SMAP_VAL/SV12SRF.001/ directory. Within this directory there is one folder: 2012.06.07. Within this folder there are two files: SV12SRF_SMAPVEX12_Forest_Soil_Roughness_20130418.xls and SV12SRF_SMAPVEX12_Forest_Soil_Roughness_20130418.xls.MET.xml

Table 1 describes the column headings and contents for the SV12SRF_SMAPVEX12_Forest_Soil_Roughness_20130418.xls file.

Table 1. Data Column Descriptions
Column Heading Description
Site_ID ID of the field and the sample point within the field
UAV_Angle Azimuth angle (from north) of the UAVSAR observation
UAV_RMS_Height Surface height variation (RMS) in the look direction of UAVSAR
UAV_Corr_Length Surface correlation length in the look direction of UAVSAR
PALS_Angle Azimuth angle (from north) of the PALS observation
PALS_RMS_Height Surface height variation (RMS) in the look direction of PALS
PALS_Corr_Length Surface correlation length in the look direction of PALS
R2_Angle Azimuth angle (from north) of the RADARSAT2 observation
R2_RMS_Height Surface height variation (RMS) in the look direction of RADARSAT2
R2_Corr_Length Surface correlation length in the look direction of RADARSAT2
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File Size

The data file is approximately 33 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

Spatial Resolution

The roughness measurements were taken over a 3 m profile.

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Temporal Coverage

Photographs were acquired at each site one time during the campaign, 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 (rms) of surface height variation: 0 - 3.21 cm
Surface correlation length: 0 - 30 cm

Missing data are represented by N/A. 

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Software and Tools

No special tools are required to view these data. A spreadsheet program which recognizes tab-delimited text files, such as Microsoft Excel, is recommended.

Quality Assessment

Due to the measurements conditions in the forest (see the Error Sources section above), the data may have larger uncertainties than the roughness measurements carried out at agricultural fields.

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Data Acquisition and Processing

The surface roughness measurements were made in the look directions of RADARSAT-2 (descending mode), UAVSAR, and PALS:

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

At each location, the surface roughness was measured using a digital camera and a 1 m long pin profiler consisting of 200 needles spaced from an interval of 5 mm. To adequately measure the correlation length, the roughness measurements were taken over a 3 m profile created by placing the one meter profiler end to end in the look direction of each Synthetic Aperture Radar (SAR) sensor: RADARSAT-2, UAVSAR, and PALS. A digital camera recorded the pin meter profiles.

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. Due to shadow, poor quality pictures were collected over some sites. Despite a second revisit, these conditions led to no data over these sites in some directions.

See more details in sections 1.2 and 2.2.2 of the SMAPVEX12 Database Report.

Derivation Techniques and Algorithms

Error Sources

A source of uncertainty inherent to the technique used comes from human error in placing the measurement equipment in the field for the measurements. The surface type and understory in the forest add to this error. Due to shadows in the forest, the quality of the pictures collected at some sites were poor. Despite a second revisit, these conditions led to no data over these sites in some directions, and for the second location at site F5.

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References and Related Publications

Contacts and Acknowledgments

Ramata Magagi
University of Sherbrooke
Sherbrooke, Québec J1K 2R1, Canada 
e-mail: Ramata.Magagi@usherbrooke.ca
phone: +1 819.821.8000

Acknowledgements: 

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

Document Information

DOCUMENT CREATION DATE

November 2013

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