Data were simulated using the TOMCAT/SLIMCAT three-dimensional offline chemical transport model, using σ-p vertical coordinates and identical stratospheric chemistry and aerosol loading, solar flux input and surface mixing ratios of long-lived source gases.

The long-term simulation (1979-2016) was performed with a T42 horizontal resolution of approximately 2.8° latitude × 2.8° longitude and 32 levels from the surface to 60 km. The model input used horizontal winds and temperature from the reanalysis data of the European Centre for Medium-Range Weather Forecasts.