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 Monitoring of trace atmospheric constituents was originally driven by scientific curiosity. It was not long before questions were raised as to what extent the observed increases in certain trace chemicals are connected to human activities and what the consequences would be for humanity if it should continue unabated.

 WMO provided a substantial contribution in converting scientifically driven events into regular monitoring.  It formally embarked on a programme of atmospheric chemistry and meteorological aspects of air pollution during the 1950s. Need for adequate information on the chemical composition of the atmosphere and on the consequences of the anthropogenic impact can be estimated on a global scale only if all measurements of the component of interest are expressed in the same units or on the same scale, i.e. the measurements performed by different countries are comparable.

 The first step has been made by WMO in the international coordination of chemical measurements during the 1957 International Geophysical Year. WMO has taken a responsibility for development of standard procedures for uniform ozone observations and establishing the Global Ozone Observing System (GO3OS). It presented a coordinated Dobson and later Breuer spectrophotometer network to measure total atmospheric ozone. The system included ozonesondes intercomparisons, preparation of the Ozone Bulletins and Ozone Assessments and support of Ozone data center in Canada.

 In the late 1960s, the Background Air Pollution Monitoring Network (BAPMoN) was established. It focused on precipitation chemistry, aerosol and carbon dioxide measurements, included regional and background stations and had WMO World data center established in USA

 During the 1970s three important atmospheric issues were addressed: (a) the threat of CFC's to the ozone layer, (b) acidification of lakes and forests in large parts of North America and Europe, caused principally by the conversion of sulphur dioxide into sulphuric acid by precipitation processes in the atmosphere and, (c) potential global warming caused by the build-up of greenhouse gases in the atmosphere. Each of these issues is now the subject of international treaties or conventions. The initial development of these agreements and the subsequent assessments of the mitigation measures they contain, rely heavily on the information derived from WMO's atmospheric composition monitoring programme.

In 1989 two observing networks BAPMoN and GO3OS were consolidated into the current WMO Global Atmosphere Watch (GAW) programme.

  25 Years of GAW
 Scientific curiosity drove the early observations of atmospheric constituents. In the 1950s, the World Meteorological Organization (WMO) launched a programme on atmospheric chemistry and the meteorological aspects of air pollution that transformed these early sporadic measurements into regular observations. This programme soon determined that characterizing atmospheric composition and its changes requires that all measurements be expressed in the same units and on the same scale, thus enabling measurements performed by different countries to be compared and combined.

01 Continuous Total Ozone Measurements

Continuous Total Ozone Measurements (from manual operations to automatic instrumentation– from the 1950s to today)

 These activities evolved in 1989 into the Global Atmosphere Watch (GAW) Programme. GAW was established in response to the growing concerns related to human impacts on atmospheric composition and the connection of atmospheric composition to weather and climate. GAW’s mission is focused on the systematic global observations of the chemical composition and related physical characteristics of the atmosphere, integrated analysis of these observations and development of predictive capacity to forecast future atmospheric composition changes (Laj et al., 2009). These observations and analyses are needed to advance the scientific understanding of the effects of the increasing influence of human activity on the global atmosphere as illustrated by such pressing societal problems as: changes in the weather and climate related to human influence on atmospheric composition, particularly, on greenhouse gases, ozone and aerosols; impacts of air pollution on human and ecosystem health and issues involving long-range transport and deposition of air pollution; and changes in UV radiation as consequences of changes in ozone atmospheric content and climate, and subsequent impact of these changes on human health and ecosystems.


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