The two-continent model evaluation exercise was set up and the results are summarised in this issue of Atmospheric Environment. The idea was to put at work the four model evaluation modes, namely, operational, diagnostic, dynamic and probabilistic evaluation.
The aim of this exercise was to collect almost all regional-scale air quality models being used for research and policy support in Europe and North America (NA) from public and private sectors and have them to simulate the air quality over North America and Europe for the year 2006.