The main global near-real-time production system (MACC_osuite) is a data assimilation and forecasting suite providing 5-day forecasts for O3, CO, NOx, SO2, HCHO, and aerosols as well as many chemical compounds from the coupled chemistry transport model.

Upgrades of the system undergo their final testing in an experimental suite (MACC_esuite), which will run in parallel to the operational suite (osuite) for some time before the decision is made to replace the osuite with the esuite.

Two forecasting suites are produced in near-real-time, one coupled to the Mozart chemistry transport model, the other coupled to the TM5 chemistry transport model. These suites do not use data assimilation to constrain the atmospheric composition fields.