Traceability of Aerosol Optical Depth Measurements to the GAW-WMO Reference Scale

The Physikalisch-Meteorologisches Observatorium Davos/World Radiation Center (Switzerland) (PMOD) operates Precision filter Radiometers (PFR) in Izaña since 2005. PFR is the Global Atmosphere Watch (GAW) reference instrument for aerosol optical depth (AOD) measurements. It was specifically designed for long‑term, high‑stability AOD monitoring following technical specifications defined by the World Meteorological Organization (WMO) within the GAW‑PFR network, and serves as the primary WMO reference for AOD traceability.

These measurements are coincident with NASA-AERONET Cimel masters, which will be also working in the frame of ACTRIS (The Aerosol, Clouds and Trace Gases Research Infrastructure) once this RI will be stablished as ERIC (European Research Infrastructure Consortium) and its activity legally starts. Izaña Atmospheric Observatory will work in collaboration with PMOD to provide a certificate of traceability between Cimel and PFR which can be used to perform an official traceability of AERONET/ACTRIS to WMO standards.