GAW-PFR Network

Atmospheric TurbidityGAW-PFR Network

GAW-PFR Network

The Global Atmosphere Watch Precision Filter Radiometer (GAW-PFR) Network is an international network of PFRs to measure aerosol optical depth (AOD) at GAW baseline stations. PMOD/WRC provides calibration services and has developed a web-based user-interface for submission of AOD data to the World Data Center for Aerosols (WDCA).

Click on above figure or here to access the GAW-PFR network website.

Motivation

The World Meteorological Organisation (WMO) instigated the Global Atmosphere Watch (GAW) programme in 1989 as a successor to the Background Air Pollution Monitoring Network (BAPMoN). During a 1993 workshop it was recommended that Aerosol Optical Depth (AOD) measurements, conducted previously under BAPMoN, should be discontinued until new instruments, methods and protocols were established to collect AOD data of known and assured quality.

Based on a recommendation by GAW experts in 1995, the World Optical Depth Research and Calibration Center (WORCC) was established in 1996 at the PMOD/WRC as one of the Swiss contributions to GAW. WORCC has since been advised by the GAW Scientific Advisory Group (SAG) for Aerosols. Twelve existing GAW stations were chosen for the deployment and operation of 12 “N” type PFRs, provided by the Swiss Government. WORCC was assigned the following tasks:

  • Development of a radiometric reference for spectral radiometry to determine AOD.
  • Development of procedures to ensure worldwide homogeneity of AOD observations.
  • Development of new instrumentation and methods for AOD.
  • Implementation of an AOD network at GAW Global observatories including quality control and quality assurance of data, called GAW-PFR.
  • Training operators to use and maintain AOD instruments.

Mandate of WORCC and Link with the GAW-PFR Network

  • Homogenisation of global AOD through provision of traceability to the World Standard Group (WSG) of sun photometers for contributing networks at co-located sites and/or periodic international filter radiometer comparisons, and further standardisation of evaluation algorithms.
  • Maintenance of the Reference (Triad) of PFR instruments suitable for contributing AOD networks at four wavelengths.
  • Long-term operation of an AOD network (GAW-PFR network) and associated stations, including submission of quality controlled data to the World Data Center for Aerosols (WDCA), and maintenance of its internal calibration hierarchy.
  • Development of a central facility with a web-based user-interface for unified processing, archiving and presentation of PFR measurements from GAW-PFR and associated stations (automisation of routine data submission and processing protocols).
  • Participation in the Aerosol Clouds and Trace Gases Research Infrastructure (ACTRIS RI) as a unit at the Calibration of Aerosol remote Sensing (CARS).
  • Development of support equipment and procedures to enable online data collection from GAW-PFR and provision of preliminary results in near real-time.

WORCC also participates in WMO expert teams and committees (e.g. Expert Team of Atmospheric Composition Measurement Quality (ET ACMQ), as well as the WMO Expert Team on the Atmospheric Composition Network Design and Evolution (ACNDE).

The GAW-PFR Network has received funding through the framework of GAW-CH and GCOS-CH, and MeteoSwiss that provided targeted support to projects of national partner institutions that contribute to the implementation of the GAW Scientific Implementation Plan and/or the GCOS Implementation Plan and the GCOS Switzerland Strategy 2017 – 2026.

Funding was provided for two projects:

  • The Global Atmosphere Watch (GAW) Precision Filter Radiometer Network  (11.2018 – 03.2021). The project concerned GAW-PFR data re-evaluation.
  • AOD Data Web Interface for Data Communication to Scientists and the Public (GAWaodIDC) (01.08.2021 – 31.01.2023). The project concerned GAW-PFR visualisation through a web interface.

Final GCOS-CH project reports can be found under the “Completed Projects” heading on the GCOS-CH website.

For further information please contact: Dr. Stelios Kazadzis, Dr. Natalia Kouremeti