ATMOSPHERIC TURBIDITY

AOD Reference PFR Triad

The WORCC standard group of three PFRs (so-called “PFR triad”) was established in 2005 by WORCC in order to fulfil the WMO mandate on: “Homogenization of global AOD  . . .

GAW-PFR AOD 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  . . .

Precision Spectro- radiometer (PSR)

The PSR was developed to upgrade and complement the filter-based PFR sun-photometer. AOD and trace gas values can be measured over a continuous range of 320-1040 nm.

Precision Filter Radiometer (PFR)

A second PFR generation has been developed to secure the continuous operation of the GAW-PFR network and its ancillary stations for the fore-seeable future . . .

Calibration Facilities

The WORCC Section has a number of calibration facilities which allow radiometers to be calibrated outdoors as well as in the laboratory.

International AOD Comparisons

Filter Radiometer Comparisons (FRCs) are organised every five years at PMOD/WRC. These AOD comparisons are conducted under various atmospheric conditions . . .

Instrumentation

Several instruments have been developed by the WORCC section for R & D as well as monitoring purposes. These include: The Lunar PFR, UV PFR and the ERMIS spectro-radiometer.

Optics Laboratories

Three optics laboratories are available to comprehensively characterise radiometers, each run by the Sections: Solar Radiometry (SRS), UV Radiometry (WCC-UV) and WORCC.

The World Optical Depth Research & Calibration Center (WORCC) develops accurate radiometric references for spectral solar radiometry which are used to determine optical depth.

The World Meteorological Organization (WMO) instigated the Global Atmosphere Watch (GAW) program in 1989 as a successor to the Background Air Pollution Monitoring Network (BAPMoN). In 1993 it was recommended that AOD measurements, conducted previously under BAPMoN, should be discontinued until new instruments, methods and protocols could be established to collect AOD data of known and assured quality. Based on a recommendation by GAW experts, the World Optical Depth Research & Calibration Center (WORCC) was established in 1996 at the PMOD/WRC in Switzerland. WORCC has since been advised by the GAW Scientific Advisory Group for Aerosols.

  • Develop accurate radiometric references for spectral solar radiometry used to determine optical depth.
  • Develop procedures to ensure world-wide homogeneity of optical depth measurements by providing transfer standards for precision filter radiometry.
  • Develop and test new instrumentation and methods for the determination of optical depth.
  • Implement a network of Precision Filter Radiometers (PFR) at Global Atmosphere Watch (GAW) stations to test methods for optical depth determination and calibration transfer.
  • Develop relevant quality control procedures in cooperation with GAW Quality Assurance/Science Activity Centers.
  • Training of staff to operate PFRs.
For further information please contact: Dr. Stelios Kazadzis, Dr. Natalia Kouremeti