StratoClim is a EC project with 28 partners from 11 countries. It will produce more reliable projections of climate Change and stratospheric ozone by a better understanding and improved representation of key processes in the Upper Troposphere and Stratosphere (UTS). Contribution from IMK-ASF: 10 years of global MIPAS observations of sulfur-containing species (mainly SO₂ and COS) will be analysed with the help of CTM runs to gain a better understanding of sulfur transport from the troposphere to the stratosphere, its chemical conversion, and the formation of sulfur aerosols; participation at an aircraft campaign dedicated to the Asian monsoon system with GLORIA.