|Instrument: TOVS : TIROS Operational Vertical Sounder|
Earth Remote Sensing Instruments
Instrument Class: Passive Remote Sensing
Instrument Type: Profilers/Sounders
Wavelength Keyword: Infrared > Thermal
Number Channels: 20
Related Data Sets
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Data acquired from the TIROS Operational Vertical Sounder (TOVS) are used to produce atmospheric soundings. The TOVS software transforms upwelling infrared and microwave radiant energy into vertical temperature and water vapor profiles. A variety of other parameters, such as total ozone, cloud height and amount, and tropopause temperature and pressure, are also derived. Approximately 50,000 soundings, spaced 80 to 300 km apart, are produced daily by two polar orbiting satellites. Objective analysis and noise screening techniques that eliminate bad, redundant, and questionable data reduce this to about 10,000 soundings per day.
TOVS, as flown aboard the Advanced TIROS-N (ATN) is a three instrument system consisting of the HIRS/2, SSU and MSU.
The High-resolution Infrared Sounder (HIRS/2) is a 20 channel instrument for taking atmospheric measurements, primarily in the IR region. The data acquired can be used to compute atmospheric temperatures from the Earth surface to 50 mb, water vapor content in three atmospheric layers, and the total ozone content of the atmospheric column. HIRS/2 will be replaced by an improved version onboard NOAA-K,L, and M in the 1990s.
The Stratospheric Sounding Unit (SSU) is a three channel instrument, provided by the United Kingdom, that uses the selective absorption technique. The pressure in a carbon dioxide gas cell in the optical path determines the spectral characteristics of each channel, and the mass of carbon dioxide in each cell determines the atmospheric level at which the weighting function of each channel peaks. It will be replaced by an advanced passive microwave sensor in the 1990s.
The Microwave Sounding Unit (MSU) is a four channel Dicke radiometer making passive microwave measurements in the 5.5-mm oxygen band. Unlike infrared instruments of TOVS, the MSU is little influenced by clouds in the field of view. An MSU is onboard NOAA-11, launched in 1988, and will be onboard NOAA-D in 1990, NOAA-I in 1991, and NOAA-J in 1992. After that, the MSU will be replaced (on 'K', 'L', and 'M') by the Advanced Microwave Sounding Unit (AMSU).
Note: For more information of these sensors, look under individual
sensor entries for each instrument:
HIGH RES. IR RAD. SOUNDER STRATOSPHERIC SOUNDING UNIT MICROWAVE
Entry taken from:
Rao, P.K., S.J. Holmes, R.K. Anderson, J.S. Winston, P.E. Lehr,
Weather Satellites: Systems, Data, and Environmental Applications,
American Meteorological Society, Boston, 1990. ISBN 0-933876-66-1
Reference online documentation:
For any query, please refer to:
ESA/ESRIN Earth Observation Help Desk
Phone: +39 06 94180777
Fax: +39 06 94180292
Instrument Owner: USA/NASA