The first comprehensive intercomparison of CFC-11, CFC-12, HF, and SF₆ satellite data was performed as part of the SPARC Data Initiative following a new "top-down" concept of satellite measurement validation and thus providing a global picture of the data characteristics. The comparisons will provide basic information on quality and consistency of the various data sets and will serve as a guide for their use in empirical studies of climate and variability, and in model-measurement comparisons.