Traceability of Solar and Lunar Direct Irradiances Measured with Precision Filter Radiometers

Two Precision Filter Radiometers (PFRs) measuring Solar and Lunar direct irradiances for the retrieval of aerosol optical depth (AOD), have been characterised and calibrated at PTB and PMOD/WRC, respectively. The measured irradiances are used in the classical Langley extrapolation method to assess the precision of the extra-terrestrial Solar and Lunar spectra as well as the accuracy of AOD measurements that can be currently achieved following the SI-traceable methodology.