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Quality Assurance (QA)


 The GAW Quality Assurance (QA) system impacts all aspects of atmospheric chemistry observations, including

  • training of station personnel;

  • assessment of infrastructures, operations and the quality of observations at the sites;

  • documentation of data submitted to the WDCs;

  • improvement of the quality and documentation of legacy data at the WDCs.

 The primary objectives of the GAW QA system are to ensure that the data in the World Data Centres (WDCs) are consistent, of known and adequate quality, supported by comprehensive metadata, and sufficiently complete to describe global atmospheric states with respect to spatial and temporal distribution.

  Conceptual Framework of the GAW Quality System


(click to enlarge)


 Five types of Central Facilities dedicated to six groups of measurement variables are operated by WMO Members and form the basis of quality assurance and data archiving for the GAW global monitoring networks. They include Central Calibration Laboratories (CCLs) that host primary standards (PS), Quality Assurance/Science Activity Centres (QA/SACs), World Calibration Centres (WCCs), Regional Calibration Centres (RCCs), and World Data Centres (WDCs) with responsibility for archiving and access to GAW data.

- List of Central Facilities -

 Long-term education, training, workshops, calibrations station audits/visits and twinning are also provided to build capacities in atmospheric sciences in the GAW network.  These Capacity building activities are of increased importance as many GAW stations in developing countries have become operational.

 for more information, please refer;

WMO/GAW Glossary of QA/QC-Related Terminology

  The principles of the GAW QA system
  • Full support of the GCOS Climate Monitoring Principles.
  • Network-wide use of only one reference standard or scale (primary standard). In consequence, there is only one institution that is responsible for this standard.
  • Full traceability to the primary standard of all measurements made by Global, Regional and Contributing GAW stations.
  • The definition of data quality objectives (DQOs). Establishment of guidelines on how to meet these quality targets, i.e., harmonized measurement techniques based on Measurement Guidelines (MGs) and Standard Operating Procedures (SOPs).
  • Establishment of MGs or SOPs for these measurements.
  • Use of detailed log books for each parameter containing comprehensive meta information related to the measurements, maintenance, and 'internal' calibrations.
  • Regular independent assessments (system and performance audits).
  • Timely submission of data and associated metadata to the responsible World Data Centre as a means of permitting independent review of data by a wider community.


  Central Calibration Laboratories (CCLs)

 Central Calibration Laboratories (CCLs) in the GAW Programme are assigned for most of the measured parameters. The main tasks of the calibration laboratories is to hosts WMO World Reference Standards and reference scales.

Terms of Reference for GAW Central Calibration Laboratories (CCLs)

  • Host in the long term (many decades) the GAW primary standard and scale for a
    particular variable.
  • Serve the needs of the other quality assurance facilities and activities of GAW.
  • Prepare or commission laboratory standards required by the GAW network members for calibration purposes.
  • Supply well-calibrated air to GAW analytical laboratories as needed for conducting
    inter-comparisons (in collaboration with the World or Regional Calibration Centres).

 All CCLs can be found under "Central Facilities


  Central Calibration Labaoratories (CCLs)

 QA/SACs are responsible for the development and implementation of the quality assurance (QA) system in the GAW programme for specific atmospheric parameters.

Terms of Reference for GAW Quality Assurance/Science Activity Centres (QA/SACs)

  • Provide an operating framework for GAW quality assurance activities and calibration
    facilities for a specific variable and geographical area of responsibility (world, regional, national).
  • Coordinate the activities of WCCs and RCCs.
  • Provide advice and support for the local QA system at individual GAW sites.
  • Co-ordinate instrument calibrations and inter-comparisons and other measurement activities.
  • Perform or oversee regular system audits at GAW sites.
  • Provide training, long-term technical help, and workshops for station scientists and technicians.
  • Promote the scientific use of GAW data, and encourage and participate in scientific collaboration.

 All QA/SACs can be found under "Central Facilities"


World, Regional Calibration Centres (WCCs, RCCs)

 GAW calibration centres are either global (WCCs) or regional (RCCs) in responsibility.  The centres are operated by institutions participating in the GAW Programme. The main tasks of the calibration centers are to link observations to World Reference Standards and to ensure network comparability/compatibility through intercomparison campaigns and regular audits.

Terms of Reference for World and/or Regional Calibration Centres (WCCs, RCCs)

  •  Assist Members operating GAW stations to link their observations to the GAW primary standard.
  •   Develop quality control procedures following the recommendations by the SAGs, support the QA of specific measurements and ensure the traceability of these measurements to the corresponding primary standard.
  •   Maintain laboratory and transfer standards that are traceable to the primary standard.
  •   Perform regular calibrations and performance audits at GAW sites using transfer standards in co-operation with the established RCCs.
  •   Provide, in co-operation with the QA/SACs, training and long-term technical help for stations.

 All WCCs and RCCs can be found under "Central Facilities






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