title: Determination of the solar calibration constant for a sun-sky radiometer: proposal of an in-situ procedure.
abstract: A new procedure is presented for determining in situ the solar calibration constant, i.e., the Sun-sky radiometer counts for a direct normal solar flux extrapolated to the top of the atmosphere. The method makes use of a modified version of the Langley plot based on the use of an inversion code of column-integrated aerosol size distribution, and it is ordinarily applied to calibrate Prede Sun-sky radiometers. To analyze how such an in situ method can work accurately, the technique has been applied to a five-month dataset obtained from measurements taken in Rome, Italy, by a Prede Sun-sky radiometer from 22 April to 5 November 2001. The precision of the in situ method has been estimated to within 1-2.5%, depending on the wavelength.
authors.affiliation: Consiglio Nazionale delle Richerche, Istituto di Scienze dell' Atmosfera e del Clima, Research Area at Roma Tor Vergata, Via del Fosso del Vavaliere 100, 00133 Rome, Italy. m.campanelli@isac.cnr.it
authors.forename: Monica
authors.initials: M
authors.lastname: Campanelli
authors.forename: Teruyuki
authors.initials: T
authors.lastname: Nakajima
authors.forename: Bruno
authors.initials: B
authors.lastname: Olivieri