Integral and difference methods for the determination of the aerosol scattering optical depth from sky brightness data

Abstract

Based on the solution of the radiative transfer equation obtained for a clear atmosphere, we have developed integral and difference methods for the determination of the aerosol scattering optical depth from sky brightness data in the solar almucantar. These approximation formulas apply to two visible wavelengths used in NASA sunphotometers (439 and 675 nm). The capabilities of these simple methods are demonstrated both using numerical simulations and through the application to field data obtained at the Meteorological Observatory of the Moscow State University with a specialized AERONET sunphotometer in 2002. The aerosol single scattering albedo retrieved using the integral method is in a good agreement with data presented at the official AERONET website http://aeronet.gsfc.nasa.gov.