Comparison of Simplified Algorithms for Atmospheric Corrections of MERIS Data over Land
- Paper number
IAC-06-B1.4.06
- Author
Dr. Juergen Telaar, University of Stuttgart, Germany
- Coauthor
Dr. Maria von Schoenermark, University of Stuttgart, Germany
- Year
2006
- Abstract
During the last decades many different algorithms for atmospheric correction have been developed, which require the knowledge of the atmospheric constituents. Another approach is to model the atmospheric reflectance as a function of both, the reflectance at the top of atmosphere (TOA) and the ground reflectance of some pixels which contain a surface with known ground reflectance. This method has the advantage that the atmospheric properties do not need to be known. The disadvantages are first that a classification is necessary to identify these pixels and second that the ground reflectance of those pixels varies within a certain range leading to some errors. This report describes two approaches to derive ground reflectances from satellite images without the need for detailed atmospheric observations. The first method makes use of the spectral signature of water, while the second method is based on the spectral signature of dark dense vegetation. Additionally a method based on the assumption of a very clear atmosphere has been developed. The aim of this work is to examine the accuracy of these methods depending on the geographic areas and atmospheric conditions in the scene. The algorithms are applied to the different spectral channels of MERIS and to MERIS data of different geographic regions. The retrieved optical depth is compared to measurements of ground stations to estimate the accuracy of the different algorithms when applied to various conditions. The different methods are furthermore analyzed to determine the effect of modeling errors and uncertainties, i.e. knowledge of the ground reflectance for the first two methods. The results show the strengths and weaknesses of the different methods when applied to MERIS data. Based on these results some guidelines are derived to decide which algorithm should be selected for which conditions, i.e. wave length and geographic region. The dark dense vegetation method is advantageous in the visible wave length range while the clear water method is superior in the infrared.
- Abstract document
- Manuscript document
IAC-06-B1.4.06.pdf (🔒 authorized access only).
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