The RADARSAT section of the CLASS web interface allows access to SAR data for authorized U.S. Government users only. It permits the users to search the CLASS inventory of RADARSAT data based on data set type as well as geographic locations and acquisition date and time. The user may then order selected data sets from the inventory for electronic delivery.
|Becoming an Authorized SAR User
Access to RADARSAT data through CLASS is available to U.S. Government or Government-sponsored users who have agreed to the terms and conditions in the RADARSAT Affiliated User Agreement.
If you qualify for access to RADARSAT data and would like to be set up as an authorized user of CLASS, please send an email to firstname.lastname@example.org providing the following information:
Name of point of contact
Once this information is received, you will be contacted regarding setting up a user account in CLASS. Please note that your U.S. Government line office will be required to submit a signed RADARSAT Affiliated User Agreement if it has not already done so.
NOAA's allocation of RADARSAT data is limited to a percentage of the U.S. Government's investment in the RADARSAT program. As such, CLASS receives only limited amounts of RADARSAT data. These data include those acquired by the U.S. National Ice Center (NIC) for operational sea ice analysis and charting.
All RADARSAT files received and ingested at CLASS since October 1997 are accessible through the web interface. In addition, certain approved RADARSAT users can also access ERS-2 data received in CLASS through the RADARSAT web interface.
All RADARSAT data sets available through CLASS are in the Committee for Earth Observing Systems (CEOS) SAR format. Each data set has one data file and one or two metadata files (depending on the processing site). These files contain variable length records of mixed ASCII and binary values. Each record contains a binary record descriptor in its first 12 bytes that gives information about the record, including the record type and length.
Data sets from the Alaska SAR Facility (ASF) have a slightly different implementation of the CEOS format than data sets from other processing sites available through CLASS. Detailed information about the ASF data set format, including a byte-by-byte breakdown of each record, can be found at the ASF Home Page at http://www.asf.alaska.edu/reference/reference_docs.html
A document containing detailed information about the data set format for other processing sites (Gatineau, Tromso, West Freugh) may be downloaded from the RSI FTP site at ftp://ftp.rsi.ca/CEOS_DFN
Please note that all RADARSAT data sets available through CLASS are distributed with the data file compressed using gzip. To uncompress these data files, you will need to use the gunzip program. The gzip and gunzip programs are free software, and can be downloaded from ftp://ftp.gnu.org/pub/gnu
RADARSAT data sets available through CLASS vary considerably in size. They range from 20 to over 100 MB, with most being between 40 and 70 MB.
|CLASS Data Set Naming Convention for SAR Data
Data sets from each of the processing sites received at CLASS are renamed using the following convention:
NSS. < sat_id > . < rec_loc > .D < date > .T < time > . < loc1 > . < loc2 > . < unique_qual > . < file_ty pe >
sat_id = satellite ID
AF = Alaska SAR Facility (Fairbanks)
date = data start date in format YYJJJ, where YY is the year and JJJ is the day of year
time = data start time in format hhmmss for hours, minutes and seconds
loc1 = lat and lon of image upper left corner in format xxxyyyy, where xxx is latitude and yyy is longitude (nearest integer number), "N" indicates negative and "P" indicates positive
loc2 = lat and lon of image lower right corner (same format as loc1)
unique_qual - used to distinguish between different data sets that map to the same name (see information above), = A on first occurrence, B on second occurrence, C on third, etc.
|Viewing SAR Data
Commercial software for RADARSAT processing and image display is available from a number of sources. The RADARSAT International (RSI) Home Page lists a number of RSI-endorsed image processing software products.
In addition, the Naval Research Laboratory (NRL) at the Stennis Space Center in Mississippi has developed the Naval Satellite Image Processing System (NSIPS), a PV-Wave based application on workstation platforms which allows SAR imagery ingest, display, and image processing, mainly for ice applications. This system has been made available at no cost to U.S. Government users; however, you still must purchase your own license for PV-Wave. For more information on NSIPS, please contact Nita Sandidge at email@example.com, or at (228)688-4812.
|RADARSAT Term Glossary
Refers to the date of the start of the data
Refers to the time of the start of the data
Refers to the satellite's relative orbit number, i.e. the revolution number at which the data were taken
Refers to the total number of seconds elapsed between the start of the data and the end of the data
Refers to the satellite from which the data were taken
Refers to the facility at which the data were acquired and processed
Refers to the latitude at the northernmost extent of the data
Refers to the longitude at the westernmost extent of the data
Refers to the latitude at the southernmost extent of the data
Refers to the longitude at the easternmost extent of the data
Refers to the size in KB of the data set (including image file and any metadata files)
Beam mode refers to the size of the image. RADARSAT has seven beam modes, ranging from 50 x 50 km to 500 x 500 km. Beam position refers to the incidence angle at which the data were acquired.
Refers to either georeferenced or geocoded. Georeferenced data sets contain information about the geographical location of the image. Geocoded data sets contain data that has been geometrically transformed to an image according to a given map projection.
Refers to the satellite's direction at the time the data were taken
Refers to the CLASS data set name for the image.
Refers to a unique numerical ID assigned to the data set for CLASS inventory purposes
Refers to the area each image pixel covers (in meters)
More information about RADARSAT can be found at:
Canadian Space Agency's (CSA) has information about RADARSAT at http://www.space.gc.ca/asc/eng/default.asp
RadarSat International (RSI) Home Page at http://www.rsi.ca