Evaluation of the performance of MERIS spectrometer data in snow cover monitoring in the boreal forest belt

This paper describes a work plan for the evaluation of the capabilities and performance of Medium Resolution Imaging Spectrometer (MERIS) data for monitoring snow covered land surfaces, specifically in the boreal forest belt. The performance of MERIS over snow in the northern latitudes is mainly estimated by comparison of time series derived from MERIS surface reflectance against values derived from Analytical Spectral Devices (ASD) Field Spec Pro JR data acquired over validation sites in Finland during the 2005 melting season. The purpose of this investigation is not to develop a snow-mapping algorithm but rather to identify generally applicable standard values for seasonally snow covered land cover reflectance and variability for improvement of existing algorithms. Accordingly, the goal is to evaluate and compare MERIS with airborne and ground-based validation spectra over typical boreal land cover types with various snow and weather conditions. Ground-based high accuracy hyperspectral data are valuable tools in detecting and specifying land cover spectral features and helping to identify them from coarser resolution satellite observations. The resulting estimates for temporal and spatial variability in spectra can be utilized to reduce errors in snow mapping algorithms in the Northern Hemisphere. The main potential for snow monitoring and limitations for the estimation of MERIS-derived standard variability for seasonally snow-covered surfaces are discussed in conclusion.