COMPARISON OF SPECTRAL RADIANCE CALIBRATIONS OF SBUV-2 SATELLITE OZONE MONITORING INSTRUMENTS USING INTEGRATING SPHERE AND FLAT-PLATE DIFFUSER TECHNIQUES

Historically, flat-plate diffusers of measured angular scattering prop erties are illuminated by NIST standards of spectral irradiance to pro vide a calculated spectral radiance standard in the wavelength region 250 nm to 340 nm for space-borne SBUV-2 instruments used to determine long-term changes in stratospheric ozone. Correspondingly, space-borne large-aperture scanning radiometers used to measure spectroradiometri c properties of Earth scenes in the red and near-infrared regions have used internally illuminated integrating spheres. The spectral radianc e of the aperture of an integrating sphere is calculated from its spec tral irradiance which is referenced to NIST standards of spectral irra diance. Spectral radiance calibration constants in the region 250 nm t o 340 nm derived using the flat-plate diffuser and spherical integrato r techniques agree to within 1 % in the wavelength region from 250 nm to 340 nm. The results presented are for the radiometric calibration o f the SBUV-2 flight model number two which is the next instrument sche duled for flight.