Uncertainty estimation of AOD for PMOD PFR, CIMEL CE318, and Prede POM sunphotometers

This document contains a comprehensive uncertainty estimate of spectral AOD retrieved from solar irradiance measurements using narrowband filter radiometers. The uncertainty estimation is aimed at reference radiometers. The uncertainty of AOD obtained from instruments operated operationally in a network will be included at a later stage. The uncertainty estimations is specifically aimed at the three main aerosol monitoring networks GAWPFR, AERONET, SKYNET