GES DISC DAAC Data Guide:
Visible Infrared Spin-Scan Radiometer Instrument Document

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Summary:

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.

Table of Contents:

• 1 Sensor/Instrument Overview
• 2 Sensor/Instrument Layout, Design, and Measurement Geometry
• 3 Manufacturer of Sensor/Instrument
• 4 Calibration
• 5 References
• 6 Glossary of Terms
• 7 List of Acronyms
• 8 Document Information

1. Sensor/Instrument Overview:

Sensor/Instrument Long Name, Sensor/Instrument Acronym:

Visible Infrared Spin-Scan Radiometer, VISSR

Visible Infrared Spin-Scan Radiometer Atmospheric Sounder, VAS

Multispectral Radiometer, MSR (also referred to as VISSR)

Sensor/Instrument Introduction:

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 subsytems. 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.

Sensor/Instrument Mission Objectives:

The VISSR was designed to provide rapid continuous viewing of local areas for regional Earth and atmospheric monitoring.

Key Variables:

Radiant and solar-reflected energy.

Scanning or Data Collection Concept/Principles of Operation:

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.

2. Sensor/Instrument Layout, Design, and Measurement Geometry:

List of Sensors:

The VISSR instrument consists of a scanning system, a radiometer telescope and infrared and visible sensors.

Sensor Description:

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 microradians. 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 microradians square. For GOES-5 through GOES-8, the sensors have a field of view (FOV) of 20 microradians (West-East direction) and 25 microradians (North-South direction). This FOV provides a ground resolution of 0.9 km. The FOV of the IR detectors is 192 microradians 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.

3. Manufacturer of Sensor/Instrument:

This information is not available at this time.

4. Calibration:

Specifications:

Tolerance:

This information is not available at this time.

Frequency of Calibration:

This information is not available at this time.

Other Calibration Information:

This information is not available at this time.

5. References:

Rao, P.K., S.J. Holmes, R.K. Anderson, J.S. Winston, and P.E. Lehr, Weather Satellites: Systems, Data, and Environmental Applications, American Meteorological Society, Boston, 1990.

Colwell, R.N. (Editor-in-Chief), Manual of Remote Sensing: Second Edition, Volumes I and II, American Society of Photogrammetry, 1983.

Cornillon, P., A Guide to Environmental Satellite Data, University of Rhode Island Marine Technical Report 79, 1982.

6. Glossary of Terms:

See the EOSDIS Glossary for a more general listing of terms related to the Earth Observing System project.

7. List of Acronyms:

See the EOSDIS Acronyms for a more general listing of terms related to the Earth Observing System project.

• DAAC Distributed Active Archive Center
• GMS Geostationary Meteorological Satellite
• GOES Geostationary Operational Environmental Satellites
• IR Infrared
• GSFC Goddard Space Flight Center
• Meteosat Meteorological Satellite
• VISSR Visible Infrared Spin-Scan Radiometer

• URL Uniform Resource Locator

8. Document Information:

Document Revision Date:Fri May 10 11:54:35 EDT 2002

July 31, 1996

Document Review Date:

July 31, 1996

Document ID:

This information is not available at this time.

Document Curator:

Suraiya Ahmad
ahmad@daac.gsfc.nasa.gov

Change History

Version 2.0

Version baselined on addition to the GES Controlled Documents List, July 31, 1996.