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).
SMAPVEX12 Surface Roughness Data for Forest Area, Version 1
|Temporal Resolution:||Not specified|
|Data Contributor(s):||Ramata Magagi|
|Metadata XML:||View Metadata Record|
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].
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).
Data are provided in an Excel file.
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:
Table 1 describes the column headings and contents for the
|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|
The data file is approximately 33 KB.
Southernmost Latitude: 49.44°N
Northernmost Latitude: 49.96°N
Westernmost Longitude: 98.51°W
Easternmost Longitude: 97.85°W
The roughness measurements were taken over a 3 m profile.
Photographs were acquired at each site one time during the campaign, from 07 June through 19 July 2012.
Parameters include root mean square (rms) of surface height variation (cm), and correlation length (cm).
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.
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.
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.
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.
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.
References and Related Publications
Contacts and Acknowledgments
University of Sherbrooke
Sherbrooke, Québec J1K 2R1, Canada
phone: +1 819.821.8000
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.
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