Overview

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 Instrument

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). Both documents are available from Goddard DAAC.

Data Products & Formats

Parameters:

• 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)
• Reflectivity
• Measured radiances (calibrated and corrected)
  for all 13 channels (0.25 to 0.34 micrometer)

 Data Format: 

The format of this dataset is identical to Nimbus 7 Solar Backscatter Ultraviolet (SBUV) data set and was reprocessed using the same algorithm (version 6) as that which was used to process the Nimbus 7 SBUV data set.

   The BUV data files are available in three formats, depending on the level of processing:

1. 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).
2. 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.
3. 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 Quality:

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.

Data Availability & Access

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 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 on-line  and can be downloaded from the anonymous FTP site.

Contacts

Dr. Suraiya Ahmad

GES DISC  DAAC

NASA Goddard Space Flight Center

Greenbelt, MD 20771

e-mail: suraiya.ahmad-1@nasa.gov

301-614-5284 (voice)

301-614-5268 (fax)

 

For information about or assistance in using any DAAC data, please contact

 

EOS Distributed Active Archive Center (DAAC)

Code 610.2

NASA Goddard Space Flight Center

Greenbelt, Maryland 20771

e-mail: help-disc@listserv.gsfc.nasa.gov

301-614-5224 (voice)

301-614-5268 (fax)

References

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]

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