The Asian monsoon anticyclone dominates the global circulation in the upper troposphere - lower stratosphere (UTLS) during NH summer, and is linked to persistent maxima in tropospheric pollutants transported upwards by deep convection and confined by the anticyclonic circulation. Satellite observations from the Microwave Limb Sounder (MLS) and the Atmospheric Chemistry Experiment (ACE) are used to document the space-time behavior of carbon monoxide and other pollutants associated with the anticyclone. We use the MOZART4 and WACCM chemical transport models to simulate this behavior, and deduce source regions and transport pathways associated with the monsoon circulation.