On the Use of Pyranometers in the Study of Spectral Solar Radiation and Atmospheric Aerosols

The zero-point deviation of Eppley precision spectral pyranometers is considered for different types of Schott filter glass hemispheres. It is found that the zero-point deviation may significantly affect the measurements of spectral global and diffuse fluxes, and may also lead to considerable errors in the estimates from pyranometer data of the influence of atmospheric aerosols on shortwave radiative transfer. When the zero-point deviation is properly corrected for, however, precision spectral pyranometers may yield precise measurements of even very low spectral irradiances.