The Backscatter Ultraviolet (BUV) spectrometer was flown on the Nimbus-4 spacecraft on April 8, 1970, into a sun synchronous polar orbit at an altitude of 1100 km, to monitor the vertical distribution and total amount of atmospheric ozone on a global scale. On this spacecraft, another UV sensor MUSE (Monitor of Ultraviolet Solar Energy) was flown to monitor changes in solar UV radiation. In addition to the UV sensors, Nimbus-4 spacecraft also carried IR based sensors [ THIR (Temperature- Humidity Infrared Radiometer); IRIS (Infrared Interferometer Spectrometer); SIRS (Satellite Infrared Spectrometer); SCR (Selective Chopper Radiometer); FWS (Filter Wedge Spectrometer] for retrieving daytime and nighttime vertical profiles of atmospheric temperature, cloud top and surface temperatures, and water vapor. IRIS measurements were also used for retrieving total column ozone.
The spacecraft performed well during the first 2.5 years. During rest of its operation period, experiments operated on a limited time basis due to an attitude problem. Satellite was turned off on September 18, 1980.
For a complete description of the Nimbus-4 experiments, see "The Nimbus IV User's Guide", (TRF B06861), NASA GSFC, March 1970 (edited by R. R. Sabatini).
The BUV spectrometer flown on Nimbus-4 satellite was the second satellite instrument designed to retrieve ozone profiles from back scattered UV radiances. The BUV instrument comprised of the double monochromators( Ebert-Fastie-type), designed to make measurements of UV spectrum of the earth in the 12 ozone absorption bands in the wavelength range from 2555 to 3398 Å with a 10 Å bandpass, and the interference filter photometer which was designed to make measurements of the UV radiation in an ozone non-absorbing 50 Å band centered at 3800 Å. The Nimbus-4 BUV provided global daylight coverage (from 80 deg N to 80 deg S) every six days. The sub-satellite point at nadir crossed the equator in increments of 27 degree in longitude between successive passes. The horizontal resolution provided by the BUV was 200km x 200km.
The objectives of the nimbus-4 BUV experiment were the determination of the total column ozone and the vertical distribution of ozone from the nadir measurement of the back-scattered UV daylight radiances in the spectral range 2500 to 3400 Å. The shorter wavelengths were used for retrieval of atmospheric ozone profile. Dr. Donald F. Heath , has been the Principal Investigator for BUV and MUSE instruments. The data-inversion algorithm was first developed by Dave and Mateer (1967), and was later improved by Mateer et al. (1971,1977) and Bhartia et al. (1996).
The complete description of the BUV experiments (by D. F. Heath, A. J. Kreuger and C. L.Mateer) can be found in the section 7 of "The Nimbus IV User's Guide" (TRF B06861), and BUV data format is given in the "User's Guide to the Nimbus-4 Backscatter Ultraviolet Experiment Data Sets" (TRF B30067). .
- Total Ozone
- Ozone mixing ratios
(at 19 pressure levels: 0.3, 0.4, 0.5, 0.7, 1.0,
1.5, 2.0, 3.0, 4.0, 5.0, 7.0, 10,
15, 20, 30, 40, 50, 70, and 100 mbar)
- Layer ozone amounts
( for 12 layers: 0-0.24, 0.24-0.49,0.49-0.99,
0.99-1.98,1.98-3.96, 3.96-7.92, 7.92-15.8, 15.8-31.7,
31.7-63.3, 63.3-127, 127-253, and 253-1013 mbar)
- Measured radiances (calibrated and corrected)
for all 13 channels (0.25 to 0.34 micrometer)
The format of this dataset is identical to Nimbus 7 Solar Backscatter Ultraviolet (SBUV) data set and was reprocessed using the same algorithm (version 5) as that which was used to process the Version 6 Nimbus 7 SBUV data set. Though later Nimbus-7 SBUV data reprocessed with version 8 algorithm was released to public, the reprocessed Nimbus-4 BUV ozone data has not been released since then.
The BUV data files have been made available in three formats, depending on the level of processing:
- High-Density (HDBUV) - Full resolution data with complete auxiliary information
- contains, scan by scan and orbit by orbit, total ozone, reflectivities, ozone mixing ratios(19 pressure levels), and layer ozone amounts(12 layers).
- Compressed Ozone (CPOZ) - Full resolution data with selected auxiliary information
The data set is a condensed version of the HDBUV.
Header Record: contains measured radiances, absorption coefficients, and instrument calibration for 13 wavelengths
Data records: contain earth-located total ozone (with and without IR cloud height information), reflectivity, ozone mixing ratios at 19 pressure levels, and layer ozone amounts for 12 layers.
- Zonal Mean Tape (ZMT) - Zonal mean data ( HDBUV data used as input)
-contains daily, weekly, monthly, and seasonal averages of total ozone, mixing ratios(19 levels), and reflectivities (include also standard deviations, maximum and minimum values, and sample size), for 10-deg latitudinal zones from 80 deg S. to 80 deg N.
|DATA SET NAME
||FORMER NSSDC ID
Eventhough, this data set was reprocessed using the same algorithm (for version 6) as that which was used to process the Nimbus 7 SBUV data set, users should note that ground truth data had been used in adjusting the BUV albedos for changes in instrument sensitivity, thus rendering "uncertainty in the derived ozone values for long-term trend study". Also, dark current counts that are zenith angle dependent and that affect the derivation of ozone profiles, especially at high altitudes, are flagged.
Available Data Period: April 1970 - May1977
The Nimbus-4 BUV Ozone profile and total ozone dataset were produced using the SBUV ozone algorithm ( version number 5 & 6) and the data was delivered to the NASA's NSSDC (National Space Science Data Center) by the Ozone Processing Team (OPT), on the 9-track, 1600 bpi magnetic tapes in IBM binary format., which were then stored at NSSDC onto 6250 bpi tapes.
In January 1995, processed BUV datasets were transferred from the NASA's NSSDC to the NASA's GSFC Distributed Active Archive Center (DAAC) on the 8-mm tapes. These data set are now made available. Please contact firstname.lastname@example.org to acquire these data products.
- For information about this dataset or assistance in using any GES DISC data, please contact
- GES DISC Help Desk:
GES DISC, Code 610.2
NASA Goddard Space Flight Center
Greenbelt, Maryland 20771
- e-mail: email@example.com
Bhartia, P.K., R.D. McPeters, C.L. Mateer, L.E. Flynn, and C. Wellemeyer, 1996: Algorithm for the estimation of vertical ozone profile from the backscattered ultraviolet (BUV) technique, J. Geophys. Res., 101, 18793-18806, 1996.
Dave, J. V. and C.L. Mateer, 1967: A preliminary study of the possibility of estimating total atmospheric ozone from satellite measurements, J. Atmos. Sci., 24, 414.
Heath, D. F., Mateer, C. L., and Kreuger, A. J., 1973: The Nimbus-4 BUV atmospheric Ozone experiment- Two Year's operation, Pure and Applied Geophysics, vol 106-108, 1238-1253.
Mateer, C. L., Heath, D.F., Kreuger, A. J., 1971: Estimation of total ozone from satellite measurements of backscattered Earth radiance, J. Atmos. Sci., 28, 1307.
Mateer, C. L, 1977: Experience with the inversion of Nimbus-4 BUV measurements to retrieve the ozone profile, in Inversion Methods in Atmospheric Remote Sounding, A. Deepak ed. (Academic, Newyork), p. 577.
Reinsel, G., Tiao, G.C., Lewis, R. 1982:A Statistical Analysis of Total Ozone Data from the Nimbus-4 BUV Satellite Experiment, Journal of the Atmospheric Sciences: Vol. 39, No. 2, pp. 418-430. [Abstract] [Full-Text]