The comparison of the darkest pixel and empirical line atmospheric correction methods to retrieve aerosol optical thickness using the radiative transfer equations

Abstract

This paper presents a comparison of the darkest pixel (DP) and empirical line (EL) atmospheric correction methods in order to examine their effectiveness to retrieve aerosol optical thickness (AOT) using the radiative transfer (RT) equations. Research has found that the DP and the EL methods are the two simplest and most effective methods of atmospheric correction; however, which of the two atmospheric correction methods is more effective in deriving accurate AOT values remains an open question. The accuracy of the DP and EL atmospheric correction methods were examined using pseudo-invariant targets in the urban area of Limassol in Cyprus, by using reflectance values before and after atmospheric correction. Eleven Landsat 5 and Landsat 7 satellite images were atmospherically corrected using both the DP and EL methods. The reflectance values following the DP and EL method of atmospheric correction were used in the radiative transfer equation to derive the AOT values. Following, an accuracy assessment was conducted comparing the in-situ AOT values as measured from sun photometers with the AOT values derived from the RT equations in order to determine the effectiveness of the DP and EL methods for retrieving AOT. The study found that the EL atmospheric correction method provided more accurate AOT values than the DP method.