Atmospheric Correction of MERIS Imagery above Case-2 Waters

Abstract

RESUME This paper describes an atmospheric correction algorithm designed for the Medium Resolution Imaging Spectrometer (MERIS) with special emphasis to case-2 waters based on inverse modeling of radiative transfer calculations by using artificial neural network techniques. The presented correction scheme is implemented as a direct inversion of spectral top-of-atmosphere (TOA) radiances into spectral remote sensing reflectances at mean sea level, with additional output of the aerosol optical thickness (AOT) at 4 wavelengths for validation purpose. In this work we apply the inversion algorithm to 8 MERIS Level 1b data tracks of the year 2002 and 2003 covering the North and Baltic Sea region. A validation of the retrieved AOTs is performed with coincident in situ sunphotometer measurements of the Aerosol Robotic Network (AERONET) from Helgoland Island. The overall root mean square error (RMSE) of the retrieved AOTs at 440, 550, 670 and 870 nm is 0.05 when using Rayleigh corrected TOA radiances and 0.073 without prior Rayleigh and ozone correction.