Significant amounts of ozone have stratospheric origin and are transported to the troposphere along deep tropopause folds. Since they influence the long-term trend of tropospheric ozone, it is therefore important to quantify the impact of STT on surface ozone concentrations. The global and regional atmospheric chemistry model system MECO(n) (''MESSy-fied ECHAM and COSMO models nested n-times'') is used to investigate such an STT-event in detail. Various sensitivity experiments are performed for a case study in March 2010. The initialisation time varies between March 23rd and 25th, the runtime between four and six days. Different spatial resolutions for the global ECHAM5 model (T106L31, T63L47, T42L90) as well as for the regional COSMO-model (0.125L40, 0.125L61) are used.