SIMEC, an environment correction for MERIS based on the NIR Similarity Spectrum

In many coastal and inland waters environment effects hamper the correct retrieval of water quality and aerosol parameters from remotely sensed imagery. Environment effects can be observed as a blurring effect caused by scattering in the atmosphere of the highly contrasting dark waters and bright land, particularly if vegetated. As the contrast is highest in the Near Infrared (NIR) the blurring effect is most visible in these NIR wavelengths. Several modeling studies have shown the dependence of the adjacency effect on mainly the aerosol optical thickness (AOT) and aerosol vertical distribution (Santer and Schmechtig 2000, Minomura et al. 2001). Corrections have been proposed for these environment effects using simulations and a LUT approach. For MERIS imagery Santer et al. (2009) proposed a method based on the single scattering approximation. This correction procedure, named ICOL (Improving Contrast between Ocean and Land) is integrated into the BEAM toolbox for the correction of MERIS imagery. According to Ruiz-Verdu et al. (2008) ICOL pre-processing has a neutral or positive effect in the estimation of water leaving reflectance, depending on the lake type.