The Asian Summer Monsoon anticyclone in the upper troposphere and lower stratosphere is recognised as key feature of the circulation that organises transport of pollutants into the stratosphere. This paper combines in-flight observations and modelling to give a detailed picture of mixing processes in this region. Measurements from the new GLORIA instrument were used to reconstruct the three-dimensional distribution of important chemical species over a region around the aircraft with 400km horizontal extent and 6km vertical extent. This provides important information about the influence on the stratospheric composition of pollutants emitted from different regions in the tropics.