VISSR
STATUS
Current
AVAILABILITY
For the GOES VISSR, the scanning system consists of a mirror that mechanically positioned to provide North to South viewing while the 100 rpm rotation of the satellite provides for West to East scanning. Each step of the mirror changes the scan angle by 192 micro-radians. A sequence of 1,821 scans is performed in order to obtain the full disk view of the Earth. The scanning mirror reflects the received radiation into a sixteen inch diameter telescope. The telescope is coupled with the eight visible detectors via a fiber-optics bundle. In addition, germanium relay lenses are used to pass received radiation to two HdCdTe infrared detectors. The sensors are arranged in a linear array oriented perpendicular to the scan direction, and thus sweep out eight parallel scan line paths as the satellite rotates. For GOES-1 through GOES-4, the sensors have a field of view (FOV) of 21 micro-radians square. For GOES-5 through GOES-8, the sensors have a field of view (FOV) of 20 micro-radians (West-East direction) and 25 micro-radians (North-South direction). This FOV provides a ground resolution of 0.9 km. The FOV of the IR detectors is 192 micro-radians thus providing equivalent coverage to the eight visible sensors. For the Meteosat platforms, the FOV is 18 degrees. The ground pixel size is 2.5 by 2.5 km for the visible and water vapor bands and 5 by 5 km for the infrared bands. VISSRs have flown on five U.S. geosynchronous weather satellites and five Japanese weather satellites (GMS) from 1974 to present. The latest Japanese satellite (GMS-5) went on-line in June 1995 and continues to provide Japan with daily weather images and data.
REQUEST PROCEDURE
SSEC Data Center Archive The Space Science and Engineering Center (SSEC) currently archives research-quality data from six different geostationary satellites. SSEC also archives point, grid and text data from the NOAAport broadcast Data from SSEC is available in many different delivery formats. http://www.ssec.wisc.edu/datacenter/delivery_format.html
Satellite Instruments
The Visible Infrared Spin-Scan Radiometer (VISSR) is an imaging device used for two-dimensional, cloud cover pictures from a geosynchronous altitude. This instrument provides for the both day and night time observations of clouds and the determination of temperatures, cloud heights and wind fields. The VISSR instrument consists of a scanning system, a telescope, and Infrared and Visible sensors. A VISSR instrument flies aboard the Geostationary Operational Environmental Satellites (GOES), the Geostationary Meteorological Satellite (GMS) and the Meteorological Satellites (Meteosat). In general, the instrumentation design and operation are similar among all three platforms. The original GOES instrument was the VISSR. The VISSR was first flown aboard the NOAA Synchronous Meteorological Satellite (SMS-1 and SMS-2). GOES-1, GOES-2 and GOES-3 flew the original VISSR instrument. The VISSR was a dual-band (visible and infrared) spin-scanning imaging device. This instrument provided the capability for day and night time observations of clouds and the determination of cloud heights, temperatures and wind fields. GOES-4 through GOES-8 were flown with a modified instrument package called the VISSR Atmospheric Sounder (VAS). The modified instrument contained a set of infrared sensors that provided an atmospheric sounder capability. The VAS retained the VISSR dual-band imaging function while expanding to six infrared channels. The additional channels allowed for the determination of surface and cloud-top temperatures as in VISSR plus three-dimensional structure of the atmospheric temperature and water-vapor distribution. Each GMS carried a VISSR and supporting subsystems. The characteristics of the GMS VISSR were essentially the same as the GOES VISSR. Each Meteosat has a payload of the Mutispectral Radiometer, which is also referred to as a VISSR. This radiometer provided image generation in the infrared region, in the water vapor absorption bands and in the visible range. In general, the instrumentation design and operation were similar among all three platforms. The VISSR is a multi-channel instrument designed to sense radiant and solar-reflected energy from sampled areas of the Earth. The multi-element spectral channels sweep east-west and west-east along a north to south path by using a two-axis mirror scan system. The instrument uses a flexible scan system to produce full-Earth disc images, sector images that contain the edges of the Earth and area scans of various sizes. Scan selection allows for rapid continuous monitoring of regional scale phenomena. At the rotation rate of 100 rpm, the full North to South view of the Earth is accomplished in 18.21 minutes.
CONTACT
Dee Wade
SSEC Data Center
Wisconsin SSEC Data Center
deew@ssc.wisc.edu
http://www.ssec.wisc.edu/datacenter/archive.html
SPECIFICATIONS
Measurment TypeImagers
Platform TypeVISSR
OrbitGEO
Spectral CoverageVis/IR eight visible detectors (sensitive to the 0.54-0.70 micron band)two of the IR detectors (sensitive to the 10.5-12.6 micron band)
Active/PassivePassive
Scan PatternFull disk 2.5 km resolution visible, 5 km resolution thermal
VariablesSST, clouds
Altitude
Inclination
Repeat Time
Wavelength to
Number of Bands
Temporal Coverage
Swath Width
Resolution 1
Resolution 2
Resolution 3
Resolution 4
REFERENCES
http://www.raytheon.com/products/vissr/ http://www.ssec.wisc.edu/datacenter/archive.html http://www2.ncdc.noaa.gov/docs/isccp/html/c3/sec3-3.htm
UPDATED ON
3 Sep 2009 13:47