Comparative studies of aerosol extinction measurements made by the SAM II and SAGE II satellite experiments

Stratospheric Aerosol Measurement (SAM) II and Stratospheric Aerosol and Gas Experiment (SAGE) II are two currently operating satellite systems designed to measure stratospheric aerosol extinction coefficients using the technique of solar occultation or limb extinction. Although each sensor is mounted aboard a different satellite, there are occasions when their measurement locations are nearly coincident in time and space, thereby providing opportunities for a measurement comparison. This paper presents results of comparative study, which demonstrates that SAM II and SAGE II are producing similar aerosol extinction profiles at 1.0 μm within their measurement errors. Since SAM II has been validated, these results show the validity of the SAGE II aerosol extinction measurements at longer wavelengths. In addition, there are occasions when locations of sunrise and sunset aerosol extinction measurements by SAGE II are nearly coincident in space and about 12 hours apart, thereby providing opportunities for a test of the consistency of SAGE II profiles. Comparisons of sunrise and sunset aerosol extinction data at four different wavelengths for some of these occasions are presented and discussed.