Characterization of the Nimbus-7 SBUV radiometer for the long-term monitoring of stratospheric ozone

Precise knowledge of in-orbit sensitivity change is critical for the successful monitoring of stratospheric ozone by satellite-based remote sensors. This paper evaluates those aspects of the in-flight operation that influence the long-term stability of the upper stratospheric ozone measurements made by the Nimbus-7 SBUV spectroradiometer and chronicles methods used to maintain the long-term albedo calibration of this UV sensor. It is shown that the instrument's calibration for the ozone measurement, the albedo calibration, has been maintained over the first 6 yr of operation to an accuracy of approximately + or - 2 percent. The instrument's wavelength calibration is shown to drift linearly with time. The knowledge of the SBUV wavelength assignment is maintained to a 0.02-nm precision.