Water vapor absorption in the visible and near infrared: results of field measurements.

Measurements of solar irradiance at the ground have been analyzed to obtain information on absorption from water vapor in the visible and near infrared. Great care has been taken in evaluating the aerosol optical thickness to obtain results compatible with theory. An automatic procedure is presented that eliminates the recordings in which modifications of the aerosol optical properties not monitored would seriously influence the determination of those of water vapor. Particular care is paid to assessing the error limits of the derived spectral attenuation parameters.