[en] The Brewer-Dobson circulation is changing under the influence of increasing greenhouse gas concentrations. We use the concept of age of air to measure the speed of this circulation. However, age of air trends derived from different types of data sets do not agree with each other. Age of air can be derived from trace gases like sulfur hexafluoride (SF6). My PhD contributes by introducing SF6 in the Belgian Assimilation System for Chemical ObsErvations (BASCOE). Three simulations have been performed using the BASCOE chemistry transport model, driven by three different reanalysis data sets. The results are validated using MIPAS and ACE-FTS satellite observations and by computing the global atmospheric lifetime for 6 long lived gases: SF6, N2O, CH4, CFC-11, CFC-12 and HCFC-22. The BASCOE model updated with the chemistry of SF6 has been used to support the development of the CAIRT satellite mission for ESA's Earth Explorer 11.
