The TOMS program began with the launch of TOMS Flight Model #1 on the Nimbus-7 spacecraft on October 24, 1978. Valid measurements started in November of that same year and the instrument continued to return data long after all other on-board experiments had failed. The TOMS instrument fell silent in May 1993. The software to derive useful information from the data returned by Nimbus 7 TOMS is the basis for the algorithm used to analyze all TOMS data and has gone through a lengthly evolutionary process bring it to the current version. The Version 7 processed data include a revised instrument calibration based on analysis of the entire 14.5 year data record (including a correction for a 0.2 nm wavelength error which caused a 3% absolute offset relative to Dobson) as well as an improved algorithm.

Algorithmic Improvements include:

• use of wavelength "triplets" that correct for errors linear in wavelength
• improved ISCCP cloud height climatology, higher resolution terrain height maps
• use of improved profile shape selection to improve total ozone at very large solar zenith angles
• use of a more accurate model for partially-clouded scenes
• improved radiative transfer calculations for table generation

More Nimbus-7 TOMS information

• The Nimbus-7 ozone profile data from the Solar Backscattered Ultraiolet Instrument(SBUV) are available.
• Here is the Nimbus-7 TOMS Version 7 User's Guide (in PDF format)
• Technical information about the Nimbus-7 spacecraft is now available.
• Here is a short MPEG movie of Nimbus-7 in orbit (153 K).
• Here is an artist's drawing of the Nimbus-7 spacecraft (42 K).
• Here is a photo of Nimbus-7 in a clean room (58 K).

Go back to Nimbus-7 TOMS data and images.

We are currently searching for an image of the original Nimbus-7 program patch. Please let us know if you have one.