The aim of GAW is to provide high quality observation data and analyses of the chemical composition of the atmosphere and its physical properties. The programme supports a worldwide network of selected monitoring stations for measuring greenhouse gases, ozone, UV radiation, aerosols, reactive gases and precipitation chemistry. The GAW network includes 30 global and over 400 regional stations, as well as 100 additional stations from contributing networks. The climate-associated aspects of the GAW programme feed directly into the Global Climate Observing System (GCOS).
The GAW framework supports a diverse range of activities under the leadership of the World Meteorological Organization (WMO), including, for example, national research programmes and international cooperation. Furthermore, it provides services such as global and regional calibration centres, which are run on behalf of the WMO by the individual member countries.