A new method is employed for retrieving the profiles of trace gas number densities from satellite-based ultraviolet-visible (UV-Vis) spectra of scattered sunlight, which are recorded from the limb atmosphere over a range of tangent heights. The slant column abundances of trace gas along the lines of sight (LOSs) are obtained by differential optical absorption spectroscopy (DOAS), and the tomographic technique is applied to such column abundances to retrieve two-dimensional (2D) concentration pro