Atmospheric correction of Landsat-8/OLI and Sentinel-2/MSI data using iCOR algorithm: validation for coastal and inland waters

L De Keukelaere,S Sterckx,S Adriaensen,E Knaeps,I Reusen,C Giardino,M Bresciani,P Hunter,C Neil,D Van Der Zande,D Vaiciute

doi:10.1080/22797254.2018.1457937

Abstract

ABSTRACTImage correction for atmospheric effects (iCOR) is an atmospheric correction tool that can process satellite data collected over coastal, inland or transitional waters and land. The tool is adaptable with minimal effort to hyper- or multi-spectral radiometric sensors. By using a single atmospheric correction implementation for land and water, discontinuities in reflectance within one scene are reduced. iCOR derives aerosol optical thickness from the image and allows for adjacency correction, which is SIMilarity Environmental Correction (SIMEC) over water. This paper illustrates the performance of iCOR for Landsat-8 OLI and Sentinel-2 MSI data acquired over water. An intercomparison of water leaving reflectance between iCOR and Aerosol Robotic Network – Ocean Color provided a quantitative assessment of performance and produced coefficient of determination (R2) higher than 0.88 in all wavebands except the 865 nm band. For inland waters, the SIMEC adjacency correction improved results in the red-edge and near-infrared region in relation to optical in situ measurements collected during field campaigns.

Highlights

Remote sensing has been proven useful in many terrestrial and aquatic applications such as crop monitoring, mapping of invasive species or obtaining water quality information
This paper describes the methodology of image correction for atmospheric effects (iCOR), previously known as OPERA (Sterckx et al, 2015), and shows preliminary results for the Operational Land Imager (OLI) on board of Landsat-8 (L8) and the MultiSpectral Imager (MSI) onboard of Sentinel-2 (S2)
This schematic can be summarised into the following steps, (i) land and water pixels are distinguished, (ii) land pixels are used to derive the AOT based on an adapted version of the method developed by Guanter (2007), (iii) an adjacency correction is performed using SIMilarity Environmental Correction (SIMEC) (Sterckx et al, 2014) over water and fixed background ranges over land targets (Berk et al, 2006), and (iv) the radiative transfer equation is solved. iCOR uses MODTRAN5 (Berk et al, 2006) LUT to perform the atmospheric correction and uses information about the solar and viewing angles (Sun zenith angle (SZA), view zenith angle (VZA) and relative azimuth angle (RAA)) and a DEM

Summary

Introduction

Remote sensing has been proven useful in many terrestrial and aquatic applications such as crop monitoring, mapping of invasive species or obtaining water quality information. Many atmospheric correction algorithms have been developed to remove these unwanted effects, multiple correction procedures are sensor specific and either developed for land Common methods for ocean colour atmospheric correction do not look at elevation or adjacency effects and make assumptions on reflectance in the near-infrared (NIR) Vanhellemont & Ruddick, 2015) wavelengths These assumptions are not valid for land targets. Land atmospheric corrections often consider a Lambertian surface, while the air-water interface has a specular reflection (Gao et al, 2009). We present an alternative atmospheric correction tool image correction for atmospheric effects (iCOR) designed to work over inland, coastal or transitional waters and land

Methods

Results

Discussion

Conclusion