Accurate correction of atmospheric propagation effects is essential for quantitative retrieval of bio-geophysical properties at the Earth's surface from satellite radiance measurements. We studied procedures to obtain the MERIS at-surface reflectance at test sites on the northern and southern rim of the Alps, characterized by significant spatial and temporal variability of the atmospheric turbidity. The analysis is based on full resolution at-sensor spectral radiance (L1b) data from MERIS acquired in summer 2003 and 2004. The 6S radiative transfer model was used to calculate the atmospheric influence and to derive at-surface spectral reflectance from the MERIS data. The aerosol properties (AOT{sub}550 and the Angstrom parameter α) required as input in 6S, were estimated using the DDV (dense dark vegetation) approach. The estimated aerosol properties and surface reflectance were validated with in situ atmospheric transmittance and spectroradiometer measurements during field campaigns at the test sites Lake Garda and Salzkammergut and compared with MERIS Level 2 (L2) data.
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