M. Blumthaler et al., MEASUREMENTS OF THE SPECTRAL AEROSOL OPTICAL DEPTH USING A SUN PHOTOMETER, Theoretical and applied climatology, 57(1-2), 1997, pp. 95-101
A sun photometer fitted with 9 narrowband interference filters from 36
8 nm to 1024 nm was used to determine the aerosol optical depth at 8 m
easuring stations in Europe. Of the 9 filters, 3 were not included in
the standard equipment of the sun photometer. Given the temporal insta
bilities of the calibration Factors of these 3 filters, meaningful res
ults for the aerosol optical depth can be achieved only if calibration
and measurements follow each other closely. Calibration was performed
using the Langley plot method. For wavelengths < 500 nm, the measured
aerosol optical depths were compared with the results of a high resol
ution spectrometer. Broadband aerosol optical depths, centred at 427 n
m, were determined with an actinometer and were also used for comparis
on. Generally, there was good agreement of the results. To characteriz
e the aerosol optical depths, the Angstrom parameters alpha and beta w
ere used. The individual measuring stations showed a clustered distrib
ution of a and beta values.