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- The objectives of the Solar Backscatter Ultraviolet (SBUV) flown on
NIMBUS-7 were to determine the vertical distribution of ozone, map the
total ozone content, and monitor the incident solar ultraviolet (UV)
irradiance and ultraviolet radiation backscattered from the earth. The
SBUV consisted of a double Ebert-Fastie spectrometer and a filter
photometer similar to the BUV on Nimbus 4. The SBUV spectrometer
measured solar UV backscattered by the earth's atmosphere at 12
wavelengths between 0.25 and 0.34 micrometer, with a spectral bandpass
of 0.001 micrometer. The SBUV used three detectors: a photomultiplier
tube (PMT) and a photodiode for the monochromator, and one photodiode
for the photometer. Both the monochromator and the photometer have
chopper wheels operating at 25 Hz. The SBUV used a depolarizer to
eliminate the sensitivity of the grating monochromator to polarization
of the backscattered radiation. The instrument's field of view (FOV)
at nadir was 0.20 rad. A roughened aluminum diffuser plate viewed the
sun for solar-spectral irradiance measurements and for calibration by
viewing a mercury-argon lamp. The diffuser plate was driven by a
stepper motor to three postions on command: SBUV, TOMS, and STOW. The
contribution functions for the eight shortest wavelengths were
centered at levels ranging from 55 to 28 km and were used to infer the
vertical ozone profile. The four longest wavelengths had contribution
functions in the troposphere which were used to compute the total
ozone amount. The SBUV spectrometer had a second mode of operation
that allowed a continuous solar-spectral scan from 0.16 to 0.4
micrometer for detailed examination of the extraterrestrial solar
spectrum and its temporal variations. A parallel photometer channel at
0.343 micrometer measured the reflectivity of the atmosphere's lower
boundary in the same 0.21-rad FOV.
A another version of the SBUV (SBUV/2) has been flown on the NOAA
Polar Orbiting series of spacecraft on NOAA-9, NOAA-11, and NOAA-14.m
The SBUV/2 was a non-scanning, nadir viewing instrument designed to
measure scene radiance in the spectral region from 160 to 400 nm. SBUV
data are used to determine the vertical distribution of and total
ozone in the atmosphere, and solar spectral irradiance.
Additional Information:
SBUV sensor: "http://www.eumetsat.de/en/index.html?area=left2.html&body
=/en/area2/cgms/ap10-12.htm&a=284&b=2&c=280&d=200&e=0"
TOMS: "http://jwocky.gsfc.nasa.gov/"
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