Multi-component aerosol modules in global models promise a much needed better seasonal and regional characterization of aerosol. However, the added complexity may have introduced many (potentially offsetting) errors. A driving force behind the new inter-comparison is the availability of more accurate aerosol products from satellite, a tighter ground network of aerosol measurements and a multitude of results from field experiments.

The Aerosol Comparisons between Observations and Models (AEROCOM) project is an open international initiative of scientists interested in the advancement of the understanding of global aerosol and its impact on climate. A large number of observations (including MODIS, POLDER, MISR, AVHHR, SeaWiFS, TOMS, AERONET and surface concentrations) and results from more than 14 global models have been assembled to document and compare the state of the art modelling of the global aerosol. A common protocol has been established and models are asked to make use of the AEROCOM emission inventories for the year 2000 and preindustrial times. Results are documented via interactive websites which give access to 2D fields and standard comparisons to observations. Regular workshops are held to discuss findings and future directions.