Global Atmosphere Watch
The Global Atmosphere Watch (GAW) is a worldwide system established by the World Meteorological Organization
World Meteorological Organization
The World Meteorological Organization is an intergovernmental organization with a membership of 189 Member States and Territories. It originated from the International Meteorological Organization , which was founded in 1873...

a United Nations
United Nations
The United Nations is an international organization whose stated aims are facilitating cooperation in international law, international security, economic development, social progress, human rights, and achievement of world peace...

 agency to monitor trends in the Earth's atmosphere
Earth's atmosphere
The atmosphere of Earth is a layer of gases surrounding the planet Earth that is retained by Earth's gravity. The atmosphere protects life on Earth by absorbing ultraviolet solar radiation, warming the surface through heat retention , and reducing temperature extremes between day and night...

. It arose out of concerns for the state of the atmosphere in the 1960s.


The Global Atmosphere Watch's mission is quite straightforward, consisting of three concise points:
  1. To make reliable, comprehensive observations of the chemical composition and selected physical characteristics of the atmosphere on global and regional scales;
  2. To provide the scientific community with the means to predict future atmospheric states;
  3. To organize assessments in support of formulating environmental policy.


The GAW program is guided by 8 strategic goals:
  • To improve the measurements programme for better geographical and temporal coverage and for near real-time monitoring capability;
  • To complete the quality assurance/quality control system;
  • To improve availability of data and promote their use;
  • To improve communication and cooperation between all GAW components and with the scientific community;
  • To identify and clarify changing roles of GAW components;
  • To maintain present and solicit new support and collaborations for the GAW programme;
  • To intensify capacity-building in developing countries;
  • To enhance the capabilities of National Meteorological and Hydrological Services in providing urban environmental air quality services.

Moreover, the programme seeks not only to understand changes in the Earth's atmosphere, but also to forecast them, and perhaps control the human activities that cause them.


The original reason for testing the atmosphere for trace chemicals was mere scientific interest, but of course, many scientists eventually wondered what effects these trace chemicals could have on the atmosphere, and on life.

The GAW's genesis began as far back as the 1950s when the World Meteorological Organization began a programme of monitoring the atmosphere for trace chemicals, and also researching air pollution
Air pollution
Air pollution is the introduction of chemicals, particulate matter, or biological materials that cause harm or discomfort to humans or other living organisms, or cause damage to the natural environment or built environment, into the atmosphere....

 from a meteorological
Meteorology is the interdisciplinary scientific study of the atmosphere. Studies in the field stretch back millennia, though significant progress in meteorology did not occur until the 18th century. The 19th century saw breakthroughs occur after observing networks developed across several countries...

 point of view. They were also responsible for monitoring ozone
Ozone , or trioxygen, is a triatomic molecule, consisting of three oxygen atoms. It is an allotrope of oxygen that is much less stable than the diatomic allotrope...

, establishing the Global Ozone Observing System (GO3OS) in 1957, in the International Geophysical Year
International Geophysical Year
The International Geophysical Year was an international scientific project that lasted from July 1, 1957, to December 31, 1958. It marked the end of a long period during the Cold War when scientific interchange between East and West was seriously interrupted...


In 1968, the United Nations called for an international conference to address world environmental problems caused by rapid industrialization. At about this time, the World Meteorological Organization set up another environmental research body, the Background Air Pollution Monitoring Network. The conference was held in Stockholm
Stockholm is the capital and the largest city of Sweden and constitutes the most populated urban area in Scandinavia. Stockholm is the most populous city in Sweden, with a population of 851,155 in the municipality , 1.37 million in the urban area , and around 2.1 million in the metropolitan area...

 in 1972, and addressed several environmental concerns, namely:
  • The threat posed to the atmosphere by chlorofluorocarbons (CFCs);
  • Acidification of lake
    A lake is a body of relatively still fresh or salt water of considerable size, localized in a basin, that is surrounded by land. Lakes are inland and not part of the ocean and therefore are distinct from lagoons, and are larger and deeper than ponds. Lakes can be contrasted with rivers or streams,...

    s and forest
    A forest, also referred to as a wood or the woods, is an area with a high density of trees. As with cities, depending where you are in the world, what is considered a forest may vary significantly in size and have various classification according to how and what of the forest is composed...

    s in North America
    North America
    North America is a continent wholly within the Northern Hemisphere and almost wholly within the Western Hemisphere. It is also considered a northern subcontinent of the Americas...

     and Europe
    Europe is, by convention, one of the world's seven continents. Comprising the westernmost peninsula of Eurasia, Europe is generally 'divided' from Asia to its east by the watershed divides of the Ural and Caucasus Mountains, the Ural River, the Caspian and Black Seas, and the waterways connecting...

     due to acid rain
    Acid rain
    Acid rain is a rain or any other form of precipitation that is unusually acidic, meaning that it possesses elevated levels of hydrogen ions . It can have harmful effects on plants, aquatic animals, and infrastructure. Acid rain is caused by emissions of carbon dioxide, sulfur dioxide and nitrogen...

  • Global warming
    Global warming
    Global warming refers to the rising average temperature of Earth's atmosphere and oceans and its projected continuation. In the last 100 years, Earth's average surface temperature increased by about with about two thirds of the increase occurring over just the last three decades...

     caused by build-up of greenhouse gases.

Indeed, it was the World Meteorological Organization's readings and observations that figured prominently at this conference. They had little good news to offer.

The GAW itself was eventually created in 1989 by combining the GO3OS and the Background Air Pollution Monitoring Network. The GAW consists of a worldwide system of observing stations and supporting facilities providing data for atmospheric assessments, and also serving as an early warning system for chemical or physical changes in the Earth's atmosphere which could be cause for environmental concern. Such changes might involve a change in ozone
Ozone , or trioxygen, is a triatomic molecule, consisting of three oxygen atoms. It is an allotrope of oxygen that is much less stable than the diatomic allotrope...

, and therefore ultraviolet
Ultraviolet light is electromagnetic radiation with a wavelength shorter than that of visible light, but longer than X-rays, in the range 10 nm to 400 nm, and energies from 3 eV to 124 eV...

, levels, levels of greenhouse gases, or precipitation chemistry, the culprit in the world's acid rain woes.


The GAW consists of a coördinated system of various components, prominent among which are:
  • measurement stations;
  • calibration and data quality centres;
  • data centres;
  • external scientific groups.

Measurement stations

More than 65 countries currently host and operate the GAW's global or regional measurement stations. There are also "contributing stations" that furnish additional data. Lately, satellite
In the context of spaceflight, a satellite is an object which has been placed into orbit by human endeavour. Such objects are sometimes called artificial satellites to distinguish them from natural satellites such as the Moon....

 programmes have also become important to the GAW, providing atmospheric data that complement ground measurements.

Calibration and data quality centres

These have the job of ensuring that all data produced by the system measure up to international standards. This is achieved by assuring a rigorous adherence to standards established by scientific advisory groups and a strict enforcement of world calibration standards. A number of programmes such as education, workshops, calibration station visits and so on are provided within the GAW programme to enhance the performance of the human component of the GAW. This has become particularly important in recent years as quite a number of stations are now operating in developing countries where further education is often a luxury enjoyed only by a small élite.

Data centres

The Global Atmosphere Watch currently has five World Data Centres, each administered by its host nation, and each responsible for gathering and storing atmospheric data from measurement stations worldwide, and making it freely available to scientists in a number of different forms.

External scientific groups

Scientific Advisory Groups (SAGs) have the job of managing and implementing the GAW programme. This includes establishing data quality objectives and standard operating procedures, and also providing guidelines and recommendations for achieving these things. Measurement methods and procedures also fall within the SAGs' domain. They are also charged with promoting twinning and training in developing countries.

External links

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