ESTIMATION OF THE TRANSMISSION OF SOLAR RADIATION THROUGH THE ATMOSPHERE WITH THE ECLIPSING METHOD OF OBSERVATIONS USING A SPECTROMETER MOUNTED ON THE SPACECRAFT
A method for estimating the transmission of sunlight through the atmosphere (or the optical thickness of the inclined path of light) is presented, accounting for the vertical profiles of gases’ concentrations and scattering of the radiation flux on aerosols. The method is focused on the use of measurement data obtained with a solar spectrometer mounted on a spacecraft. The estimation algorithm is given both in general form and as specific application to the spectrometer SAGE-III designed in the USA. From 2001 to 2005, this device carried out measurements from the platform of the Russian spacecraft METEOR3M. The data were processed at the Central Aerological Observatory (CAO). Present day interest in this methodological issue is due to the fact that the latest version of SAGE-III solar spectrometer was launched in February 2017 by NASA (USA) using the International Space Station (ISS). The purpose of this article is to give a brief overview of the basic concepts and approaches necessary for understanding the influence of the gas and aerosol composition of the atmosphere on the spectra recorded by the above-mentioned device installed on an orbital spacecraft. Some general issues of the organization of spectral measurements of the composition of the atmosphere using spacecraft are also discussed.