The Global Atmosphere Watch (GAW) programme coordinates the effort of 24 global and some 700 regional atmospheric monitoring stations to produce data that are relevant to climate change and air quality.

The Earth’s atmosphere consists of nitrogen (78.1%), oxygen (21%) and trace quantities of many other gases and aerosols, among them water vapour, carbon dioxide, ozone, and methane. Human activities are disturbing the delicate equilibrium of the atmospheric environment. Out of growing concern about climate change and air quality issues, the World Meteorological Organization (WMO) has initiated the Global Atmosphere Watch (GAW) programme. This is a voluntary programme of WMO member countries and is the atmospheric chemistry component of the Global Climate Observing System (GCOS).

The mission of the Global Atmosphere Watch, taking into account the Integrated Global Atmospheric Chemistry Observations (IGACO) strategy, is to

• Reduce environmental risks to society and meet the requirements of environmental conventions.

• Strengthen capabilities to predict climate, weather and air quality.

• Contribute to scientific assessments in support of environmental policy.

Through

• Maintaining and applying global, long-term observations of the chemical composition and selected physical characteristics of the atmosphere.

• Emphasising quality assurance and quality control.

• Delivering integrated products and services of relevance to users.

The range of atmospheric measurements currently supported under the GAW umbrella covers more than 100 parameters including

• Greenhouse gases
• Ozone
• Solar radiation
• Precipitation chemistry
• Aerosols and optical depth
• Reactive gases
• Meteorological parameters
• Radio nuclides

At the core of GAW are the stations which carry out the actual measurements. GAW has established a support structure to support these operations, strengthen the programme and guide its strategic development. It consists of

• The GAW Secretariat at WMO headquarters in Geneva to coordinate network-wide activities
•  Scientific Advisory Groups (SAGs) to guide the scientific development of the programme
• Quality Assurance/Scientific Activity Centres (QA/SACs) to deal with data quality issues, promote data use, further capacity building and other tasks specific to each QA/SAC
• World Calibration Centres (WCCs) to ensure the traceability of measurements made at global stations to designated Reference Standards; and to support Regional Calibration Centres (RCCs) that in turn ensure the traceability of measurements made at regional stations
• Reference Standards maintained and distributed by designated laboratories
• World Data Centres to archive submitted measurement data and to disseminate this information in coherent data formats.

see also: GAW Strategic Plan: 2008-2015 (WMO GAW Report Nr. 172)

GAW at Empa
The Swiss Federal Laboratories for Materials Testing and Research (Empa) have been designated by WMO to operate the World Calibration Centre for Surface Ozone, Carbon Monoxide and Methane (WCC-EMPA) , as well as a Quality Assurance/Scientific Activity Centre (QA/SAC Switzerland). Funding for both activities by MeteoSwiss is greatfully acknowledged.

Mission statement

The mission of WCC-EMPA and QA/SAC Switzerland is to improve and maintain the quality and public access of surface ozone, carbon monoxide and methane data measured at Global Atmosphere Watch stations, primarily through inter-comparison and calibration of instrumentation, one-to-one training and workshops, as well as continuous operational and stratetic support for the GAW programme, in order to contribute to the scientific basis of our understanding of climate change.

Further Information
Please direct questions and/or comments about Empa’s GAW activities to Brigitte Buchmann (Head of section), Jörg Klausen (QA/SAC Switzerland), or Christoph Zellweger (WCC-EMPA).