The Improved Stratospheric and Mesospheric Sounder (ISAMS) measured vertical profiles of temperature and a number of atmospheric constituents. ISAMS was built by an instrument team based at Oxford University and launched on the Upper Atmosphere Research Satellite (UARS) on 12th September 1991 and operated until July 1992. The Principal Investigator is Prof. Frederick Taylor.

ISAMS is an infra-red radiometer, which observes thermal emission from the Earth's limb. The technique of pressure modulator radiometry is used to derive vertical profiles of temperature, mixing ratios of carbon monoxide (CO), water vapour (H2O), methane (CH4), ozone (O3), nitric acid (HNO3), dinitrogen pentoxide (N2O5), nitrogen dioxide (NO2) and nitrous oxide (N2O) and aerosol extinction. Further details can be found in the help file written at the BADC.

The data coverage extends from 80°S to 80°N, but at any one time this is usually restricted to 34°S to 80°N or 34°N to 80°S. The vertical coverage of the measurements is from the tropopause to the mesopause (15-80 km). The range over which retrievals are valid is outlined in the help file.

The BADC holds ISAMS data at level 3A and version 10 and ISAMS data at level 2 (uninterpolated profiles at measurement locations) and version 8, the latter has restricted access.