Operational method to correct VEGETATION satellite measurements from atmospheric effects

SMAC (Simplified Method for Atmospheric Correction, Rahman and Dedieu, 1994) is a method which allows one to correct atmospheric effects of satellite data time series. A new version has been developed and is presented in this paper. It has been used to correct the atmospheric effects for the VEGETATION data. The principle of the method is always the same as in the previous version. SMAC method allows one to estimate surface reflectance from top of atmosphere reflectances and the knowledge of the state of the atmosphere (water vapour, ozone and aerosol contents). The scattering and absorption processus are parameterized by analytical formulations whose coefficients, which are depending on the spectral bandwith of the sensor, are fitted against the 6S radiative transfer reference code (version 4.1). Improvements fall on the best taking into account of multiple scattering and the coupling between aerosols and molecule, new gaseous transmission, and the taking into account of the altitude of the target. Two ways are proposed to estimate the atmospheric reflectance. The first one is entirely analytical and has been revised in front of the first version of SMAC to take into account the upgrade in radiative transfer code version, the second one is based on the use of the successive orders of scattering method. Merits of the upgraded SMAC method are conserved. It is able to fulfil the specifications of the project in terms of operationality and accuracy.