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CLPX-Satellite: Radarsat Synthetic Aperture Radar Imagery

Summary

This data set consists of time-series spaceborne Synthetic Aperture Radar (SAR) imagery of the three Cold Land Processes Field Experiment (CLPX) Meso-cell Study Areas (MSAs) (Fraser, Rabbit Ears, and North Park) acquired by the RADARSAT-1 Synthetic Aperture Radar (SAR). Images are derived from C-band (5.3 GHz frequency, 5.66 cm wavelength), HH-polarization, standard beam data for multiple incidence angles. SAR data were acquired through the Alaska Satellite Facility (ASF) and post-processed at the Jet Propulsion Laboratory, California Institute of Technology, for derivation of ancillary data and database assembly. The data series consists of 195 individual radar scenes acquired from 17 February to 23 June 2003. Calibrated radar backscatter images are provided in binary format together with header and facility data record information for each image.

Note that the Canadian Space Agency (CSA) holds copyrights over all RADARSAT-1 SAR data. NASA/NOAA-approved SAR researchers can obtain these data directly from ASF, as per agreements between NASA/NOAA and CSA. No commercial use is allowed of the data or any products derived there from. Users of this data must submit a Research Agreement to ASF.

The NASA CLPX is a multi-sensor, multi-scale experiment that focuses on extending a local-scale understanding of water fluxes, storage, and transformations to regional and global scales. Within a framework of nested study areas in the central Rocky Mountains of the western United States, ranging from 1-ha to 160,000 km2, intensive ground, airborne, and spaceborne observations are collected. Data collection focuses on two seasons: mid-winter, when conditions are generally frozen and dry, and early spring, a transitional period when both frozen and thawed, dry and wet conditions are widespread.

Citing These Data

McDonald, K. C. 2005. CLPX-Satellite: Radarsat Synthetic Aperture Radar Imagery. [indicate subset used]. Boulder, Colorado USA: NASA DAAC at the National Snow and Ice Data Center.

Overview Table

Category Description
Data format Binary image data; each file has an associated ASCII header file and a facility data record file. There is also one Microsoft Excel worksheet.
Spatial coverage Appx. 100 km x 100 km images, each including at least one of the following points within the MSAs:
~40.5° N, 106.7° W (Rabbit Ears MSA)
~40.7° N, 106.3° W (North Park MSA)
~39.9° N, 105.9° W (Fraser MSA)
Spatial resolution: 20 meters (range) and 32 meters (azimuth), nominal.
Temporal coverage and resolution 17 February to 23 June 2003, repeat-pass data
Total File size Approximately 12.8 GB total
Parameter(s) HH-polarized C-band radar backscatter coefficient
Procedures for obtaining data Data are available via FTP

Table of Contents

1. Contacts
2. Detailed Data Description
3. Data Access
4. References and Related Publications
5. Document Information

1. Contacts

Investigator(s) Name and Title

Kyle C. McDonald
Jet Propulsion Lab
California Institute of Technology
4800 Oak Grove Drive
Pasadena , CA 91109-8099

Technical Contact

NSIDC User Services
National Snow and Ice Data Center
CIRES, 449 UCB
University of Colorado
Boulder, CO 80309-0449  USA
phone: +1 303.492.6199
fax: +1 303.492.2468
form: Contact NSIDC User Services
e-mail: nsidc@nsidc.org

2. Detailed Data Description

This data set consists of time-series spaceborne Synthetic Aperture Radar (SAR) imagery of the three CLPX MSAs (Fraser, Rabbit Ears, and North Park) acquired by the C-band (5.3 GHz frequency, 5.66 cm wavelength) HH-polarization RADARSAT-1 Synthetic Aperture Radar (SAR). Images are derived Standard Beam data for multiple incidence angles. The RADARSAT-1 SAR instrument has seven standard beams with incidence angles ranging from 19 to 49 degrees, each with a ground swath near 100 km. The image products provided in this data set cover approximately 100 km x 100 km, with 12.5 meter pixel spacing (~25 meter resolution) corresponding to the full resolution images. SAR data were acquired through the Alaska Satellite Facility and post-processed at the Jet Propulsion Laboratory, California Institute of Technology, for derivation of ancillary data and assembly of the database. The data series consists of 195 individual radar scenes, acquired from February 17 to June 23, 2003 . Calibrated radar backscatter images are provided in binary format together with header and ancillary (Facility Data Record) information for each image. Facility Data Record (FDR) files associated with each SAR scene provide detailed information on scenes geolocation, sensor configuration, and other data acquisition details.

Format

Image data files are in binary format, 8192 samples x 8192 lines. Each file has an associated ASCII header file and a facility data record file.

A Microsoft Excel file “RADARSAT_Listing.xls” provides a tabulation of the SAR scenes provided in the database (Column A), and separate listings of those providing at least partial coverage of the Fraser MSA (Column B), the North Park MSA (Column C), and the Rabbit Ears MSA (Column D).

File Naming Convention

Data files are named by year, mode, day of year, platform, center latitude, and center longitude. The naming format is <root>.SSS where

<root> = yyMddd(rdf)AAAwBBBBaimg, with

yy = year of acquisition (03 = 2003)
M = orbital node of acquisition (a = ascending; d = descending)
ddd = day-of-year of acquisition
(rdf ) = platform (RADARSAT data full-resolution)
AAA = 10 * approximate latitude of image center (north latitude is assumed)
w = w; corresponds to West longitude
BBBB = 10 * approximate longitude of image center
aimg = aimg (corresponds to image data)

The suffix designator, SSS, indicates the type of file:

<root>.byt = byte image data file
<root>.hdr = header information for the byte file
<root>.facdr = facility data record

For example, the data file “03a051rdf399w1062aimg.byt” corresponds to the byte data for the image acquired on day of year 051 of 2003, on the ascending orbital node, with approximate image center at 39.9 degrees north latitude and 106.2 degrees west longitude. The data file “03a051rdf399w1062aimg.hdr” contains the corresponding header information, and “03a051rdf399w1062aimg.facdr” contains the corresponding facility data record information.

File Size

Byte-formatted (*.byt) data files are 67 megabytes each. Header (*.hdr) files are 553 bytes each, and Facility Data Record (*.facdr) files are 5589 bytes each.

Spatial Coverage

Each SAR scene includes at least one reference latitude/longitude point within a CLPX MSA: North Park MSA (~40.7° N, 106.3° W), Rabbit Ears MSA (~40.5° N, 106.°7 W) or Fraser MSA (~39.9° N, 105.9° W). Of the 195 scenes in the database, 112 include coverage of the Fraser MSA, 92 include coverage of the Rabbit Ears MSA, and 111 include coverage of the North Park MSA.

Spatial Coverage Map:

The following map shows the CLPX Large Regional Study Area:

Spatial Resolution

Images are at a nominal spatial resolution of 20 meters (range) and 32 meters (azimuth). Data are provided at 12.5 meter pixel spacings.

Temporal Coverage

Data were collected between 17 February and 23 June 2003.

Parameter or Variable

SAR scenes provide HH-polarized C-band (5.3 GHz, 5.66 cm) radar backscatter coefficient.

Sample Data Record

The following is an example of the header file (03a051rdf395w1062aimg.hdr):

srh                               ; Data file type
8192              8192            ; Data file dimensions
12.50000000       12.50000000     ; Post Spacing
-0.00000000       -0.00000000     ; Starting corner position (s,c)
39.04964667  -106.72640409  349.14435770 ; Peg position (WGS-84)
1                                 ; Magnitude Bytes per Pixel
1.00000000        0.00000000      ; Magnitude Scale and Shift

The following is an example Facility Data Record file (03a051rdf395w1062aimg.facdr):

Calibration Comments: This CPF created for post-AMM right-looking                                                                                                  
********** begin of Facility Related Data record **************

Data take id = 	R13808004     
SPS image identifier = 	099G1S013  
UTC year of image correlation = 	2003 
UTC time of image correlation = 	271:21:58:37.000 
Name of site covered = 	099G1S013                        
UTC year at the image center = 	2003 
UTC time at the image center = 	051:00:57:48.003 
Latitude of the image center = 	39.5928879
Longitude of the image center = 	-106.2591629
Lat at start of image frame in near swath = 	39.9607773
Long at start of image frame in near swath = 	-106.9614944
Lat at end of image frame in near swath = 	39.0500336
Long at end of image frame in near swath = 	-106.7266464
Lat at start of image frame in far swath = 	40.1327477
Long at start of image frame in far swath = 	-105.7828674
Lat at end of image frame in far swath = 	39.2219849
Long at end of image frame in far swath = 	-105.5640564
Actual swath width (km) in azimuth direction = 	102.4000015
Actual swath width (km) in range direction = 	102.4000015
Actual (no filler) number of pixels per line = 	8192
Actual (no filler) number of image lines = 	8192
Total (with filler) number of pixels per line = 	8192
Total (with filler) number of image lines = 	8192
Identification label of the media written to = 	       
Location on the DCRSI where data begins = 	           208984
Location on the DCRSI where data ends = 	           210484
Name of platform for the transmitting sensor = 	RADARSAT-1       
Sensor and mode of operation = 	RSAT-1-C -    -HH                
Pulse repetition frequency (prf) = 	1361.0054932
SAR antenna look angle = 	29.4912567
Data rate = 	105.0000000
Data window position = 	175.2622986
Range gate delay = 	6054.0429688
Track angle to True North = 	349.8537903
Flag indicating whether the pass is asc/desc = 	A 
Altitude of the spacecraft at image center = 	796.6301880
Spacecraft X-position at the image center = 	3410.184326200000214
Spacecraft Y-position at the image center = 	4450.339843800000381
Spacecraft Z-position at the image center = 	4463.461914100000286
Spacecraft X-velocity at the image center = 	-1650.401123000000098
Spacecraft Y-velocity at the image center = 	-4490.695800800000143
Spacecraft Z-velocity at the image center = 	5722.789062500000000
Spacecraft roll at the image center = 	0
Spacecraft yaw at the image center = 	0
Spacecraft pitch at the image center = 	0
Quality flag for the spacecraft roll = 	0
Quality flag for the spacecraft yaw = 	0
Quality flag for the spacecraft pitch = 	0
Spacecraft roll rate at the image center = 	0.0012097
Spacecraft yaw rate at the image center = 	-0.0005039
Spacecraft pitch rate at the image center = 	-0.0623135
Quality flag for the spacecraft roll rate = 	1
Quality flag for the spacecraft yaw rate = 	1
Quality flag for the spacecraft pitch rate = 	1
Radius of the earth at nadir = 	6369.8212891
Radius of the earth at image center = 	6369.4995117
Incidence angle at the center of the image = 	33.4449997
Version of the ASP = 	3.4     
Image processing type identifier = 	SF 
Type of Ephemeris used identifier = 	R 
Effective number of looks in azimuth = 	4.0000000
Effective number of looks in range = 	1.0000000
Weighting pedestal height in azimuth = 	0.9230987
Weighting pedestal height in range = 	0.8912676
Look energy normalization flag = 	NOT 
Processing induced distortions in azimuth = 	0.0000000
Processing induced distortions in range = 	0.0000000
Receiver gain = 	0.0000000
Swath velocity = 	6612.0209961
Squint angle = 	0.2774860
Ave. terrain height above Geoid at center = 	0.0000000
Processor gain = 	   0
Flag indicating if Doppler Skew was removed = 	YES 
Ground range / slant range flag = 	GROUND 
Slant range to the first image pixel = 	907.4782104
Slant range to the last image pixel = 	964.0148926
Start sample of signal data range line = 	0
Flag indicating whether clutterlock was used = 	YES 
Doppler frequency at the near range = 	-6811.2304688
Doppler frequency slope = 	-0.2346125
Doppler frequency quadratic term = 	0.0000000

3. Data Access

Data Access

Data are available via FTP at ftp://clp@sidads.colorado.edu/satellite/nsidc0146_radarsat/

Data Restrictions

The Canadian Space Agency (CSA) holds copyrights over all RADARSAT-1 SAR data. NASA/NOAA-approved SAR researchers are the primary people who obtain these data directly from ASF, as per agreements between NASA/NOAA and CSA. No commercial use is allowed of the data or any products derived there from.

Users of this data must submit a Research Agreement to ASF.

The data may not be reproduced or distributed to any other parties, except that they may be shared among the CLPX research team and with other researchers who have a signed research agreement with ASF. If requested, users should provide a copy of research results including derived data sets, algorithms, models, and documentation, to the ASF for archive and distribution. Products which involved ASF data in its production can only be freely distributed if it is in such a form that the original backscatter values cannot be derived from it.

Special Conditions for RADARSAT Data:

 The intellectual property rights of RADARSAT data are reserved solely for the Canadian Space Agency (CSA), and users are entitled only to the right to utilize the data. Users agree to clearly mark all RADARSAT data, irrespective of the form in which it is reproduced, in such a way that the CSA copyright is plain to all, as follows: “© Canadian Space Agency (year of reception)."

Reports or publications describing RADARSAT experiments which are copyrighted must provide royalty free rights for NASA, NOAA, CSA and RADARSAT International (RSI) to reproduce or use such work for their own purposes.

Related Data Collections

All CLPX Data Sets

4. References and Related Publications

Detailed information concerning RADARSAT operation and processing may be found on the ASF web site ( http://www.asf.alaska.edu).

5. Document Information

List of Acronyms

CLPX = NASA Cold Land Processes Field Experiment
IOP = Intensive Observation Period
ISA = Intensive Study Area
LRSA = Large Regional Study Area
LSOS = Local Scale Observation Site
MSA = Meso-cell Study Area

Document Creation Date

January 15, 2005