The present project aims at the geophysical validation, from pole to pole and on the long term, of key ozone-related level-2 products (O3, NO2, BrO, OClO, and ClO) from GOMOS, MIPAS and SCIAMACHY onboard ENVISAT-1, and at a contribution to the maturation of the related level-1b-to-2 data processors. Application data processing will be used to convert level-2 data into a more suitable format for validation and scientific end-users. The respective performances of the ENVISAT data products, and their sensitivity to various relevant parameters, will be investigated from the Arctic to the Antarctic, over a variety of geophysical conditions. The impact of these performances on specific atmospheric chemistry studies will be emphasised. The pseudo-global investigations will rely on correlative studies of ENVISAT data with high-quality ground-based, in situ and balloon observations associated with the Network for the Detection of Stratospheric Change (NDSC).