Ten years' data from the Total Ozone Mapping Spectrometer on the polar-orbiting Nimbus 7 satellite are now available by computer. Magnetic tapes with TOMS data from November 1978 to the present have been added to the archives of data sets maintained by the National Space Science Data Center at NASA Goddard Space Flight Center in Greenbelt, Md. The most recent year of ozone data can be accessed directly from NSSDC computers.
TOMS measures the ratio of radiance backscattered by Earth's atmosphere to extraterrestrial solar irradiance in 6 selected wavelength bands in the ultraviolet spectrum. Total column ozone values are derived from those measurements. TOMS scans across the satellite orbital track to produce detailed global maps of ozone on a daily basis.