The mission of GAW is to
- Reduce environmental risks to society and meet the requirements of environmental conventions,
- Strengthen capabilities to predict climate, weather and air quality, and
- Contribute to scientific assessments in support of environmental policy.
- Maintaining and applying global, long-term observations of the chemical composition and selected physical characteristics of the atmosphere,
- Emphasising quality assurance and quality control, and
- Delivering integrated products and services of relevance to users.
The GAW Programme is implemented and undertaken by WMO Members and supported by international scientific communities. Together, these communities perform long-term observations of chemical composition and related physical characteristics of the atmosphere on a global scale, emphasizing quality assurance and quality control of the data, developing appropriate analysis and modelling tools and providing integrated products and services to users.
Since its beginning, GAW has fulfilled a mandate from WMO Members by responding to their needs and clearly linking to the plans of national, regional, and international observing projects, programs, systems and strategies, e.g.:
- In providing a comprehensive set of high quality and long-term observations of atmospheric composition to support the United Nations Framework Convention on Climate Change (UNFCCC), especially by contributing to the implementation plan for the Global Climate Observing System (GCOS) (WMO, 2003a), the Intergovernmental Panel on Climate Change (IPCC) and to the development of Global Framework for Climate Services (GFCS).
- In supporting the Montreal Protocol for the Protection of the Ozone Layer and follow-up amendments.
- In supporting the Convention on Long-Range Transboundary Air Pollution (CLRTAP).
- In providing reliable observations and forecasting tools to support assessment of the temporal and spatial variability of aerosols (including sand and dust) and reactive gases required to understand the impact of air quality on human health, ecosystems and infrastructure security.
- In providing guidance for optimizing regional observation networks (potential contributing networks) that address atmospheric composition and related physical parameter observations.
- In promoting high-quality observations and enhancing the use of GAW’s quality controlled data and inferred products in routine/operational services and research activities.
- In supporting studies on environmental protection, including protecting the health of marine and other ecosystems.
- In providing GAW products supporting agriculture and food security aspects.
The importance of atmospheric composition in the above matters was emphasized in resolutions from the Seventeenth World Meteorological Congress, which stressed the need to enhance the capacity of NMHSs to deliver on their mission by developing and improving competent human resources, technical and institutional capacities and infrastructure; particularly in countries where the capability to maintain high standards of observations, data and metadata is problematic. It also included Resolution 60 of the 17th Congress, which urges members to strengthen their support to the framework of the GCOS Essential Climate Variables (ECVs) in the collection and supply of data and products to support the GFCS on a free and unrestricted basis. Among others, GCOS ECVs include data on the composition of the atmosphere including aerosols and their precursors, greenhouse gas and atmospheric ozone data together with climate relevant cryosphere data, including glacial monitoring.
The main GAW achievements of the last 25 years are long-time records of globally harmonized data sets for various trace gases, aerosols, deposition and UV radiation with the highest-possible accuracy, quantified with common procedures within the GAW Programme, and their use in the establishment of the long-term trends on the global scale.