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).

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):
  • Microsoft Excel
Spatial Coverage:
N: 49.96, 
S: 49.44, 
E: -97.85, 
W: -98.51
Platform(s):GROUND-BASED OBSERVATIONS
Spatial Resolution:
  • Varies
Sensor(s):CAMERAS
Temporal Coverage:
  • 7 June 2012 to 19 July 2012
Version(s):V1
Temporal ResolutionNot specifiedMetadata XML:View Metadata Record
Data Contributor(s):Ramata Magagi

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.

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: https://doi.org/10.5067/0OCZDB099FWR. [Date Accessed].
Created: 
5 March 2020
Last modified: 
5 March 2020

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). Measurements were taken within each SMAPVEX12 forest 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 - 3.21 cm and for correlation length are 0 - 30 cm. Missing data are represented by N/A. 

File Information

Format and File Contents

Data are provided in an Excel file (SV12SRF_SMAPVEX12_Forest_Soil_Roughness_20130418.xls). See Table 1 for descriptions of the column headings and contents. Also provided is a text file (Field_Sites_ver4_coords.txt) containing the UTM coordinates of the each sampling point (see Table 2).

Table 1. Data Column Descriptions for SV12SRF_SMAPVEX12_Forest_Soil_Roughness_20130418.xls

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
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

The roughness measurements were taken over a 3 m profile.

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 once at each site during the campaign, from 07 June through 19 July 2012.

Software and Tools

No special tools are required to read these data. A spreadsheet program such as Microsoft Excel is recommended for the data file, while any text editor or Web browser will display the geolocation file.

Data Acquisition and Processing

Acquisition

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 SAR sensor. 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.

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.

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.

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

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

Acknowledgments

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

DOCUMENT REVISION DATE

March 2020

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