Atmospheric lifetime of sulphur hexafluoride (SF6) and five other trace gases in the BASCOE model driven by three reanalyses

In this work, sulphur hexafluoride (SF 6 ), which is often used as a tracer for stratospheric transport due to its inertness in the stratosphere and nearly linear growth rate in the troposphere, is included in the chemistry transport model (CTM) of the Belgian Assimilation System for Chemical ObsErvations (BASCOE).Sink and recovery reactions for this species are implemented in the model, which has a top in the mesosphere at 0.01 hPa.The simulated SF 6 distributions are compared with MIPAS and ACE-FTS observations and the global atmospheric lifetime is computed from CTM runs driven by three recent meteorological reanalyses: ERA5, MERRA2 and JRA-3Q.The results show that BASCOE SF 6 profiles are generally within 10 % of the satellite observations below 10 hPa, although discrepancies increase at higher altitudes.The global atmospheric lifetime is used as an additional diagnostic for the implementation of the chemistry in the mesosphere, where satellite measurements are unavailable.The derived SF 6 lifetimes are 2646 years with ERA5, 1909 years with MERRA2 and 2147 years with JRA-3Q, in accordance with recent literature.Due to the large spread of published lifetimes for SF 6 , the study is extended to N 2 O, CH 4 , CFC-11, CFC-12 and HCFC-22, to validate the SF 6 results.The lifetimes for these species are in agreement with previously reported values, and their spread between simulations is smaller compared to SF 6 .This analysis highlights the sensitivity of SF 6 to the input reanalysis data sets and thus to differences in dynamics.