A profiling algorithm based on the Optimal Estimation Method (OEM) has been developed at IASB-BIRA in order to provide low vertical resolution stratospheric NO2 profiles from ground-based zenith-sky DOAS observations. This algorithm has been applied to observational data from the NDACC (Network for the Detection of Atmospheric Composition Change, formerly NDSC) stations of Harestua (60°N, 11°E) and Reunion Island (21°S, 55°E). The reliability of our NO2 retrievals has been verified through comparisons with correlative satellite (HALOE and POAM III) and balloon (SAOZ and LPMA/DOAS) observations. Here, stratospheric NO2 profiles and columns retrieved at Harestua and Reunion Island are used to validate the SCIAMACHY NO2 operational products (version OL 3.0). Both limb profiles and nadir columns are included in our validation study. It should be noted that comparisons are performed in the same photochemical conditions owing to the inclusion of a stacked box photochemical model in the forward model of our profiling algorithm.