ABSTRACTS

Oral Session 10 | Thursday, October 6, 15:40–16:00 | Abstract 514

AN EMPIRICAL ALGORITHM FOR ESTIMATING COLORED DISSOLVED ORGANIC MATTER FROM LANDSAT 8 AND SENTINEL 2 IMAGERY OVER COASTAL WATER

Sentinel-2/MSI and Landsat-8/OLI sensors enable the mapping of colored dissolved organic matter (CDOM) from space. Most remote-sensing algorithms derive CDOM absorption (acdom) for inland waters at 440 nm, which is affected by the chlorophyll-a (Chl-a) absorption peak. This study aims to develop a new remote-sensing algorithm to estimate acdom in coastal water at 412 nm, a wavelength less affected by Chl-a absorption. Several types of empirical algorithms were tested on a mix of synthetic and in situ datasets collected from global coastal water. Two atmospheric correction algorithms (ACOLITE and Polymer) after application of top-of-atmosphere gains and noise propagation exercises, were tested. In addition, a scheme separating the water into two classes was proposed, allowing to better adapt the algorithms to different magnitudes of acdom. Based on a independent in situ validation data set, the selected empirical algorithm presents a mean absolute percentage difference (MAPD) of 31% for both sensors, and performs better than a recently published semi-analytical algorithm. The combination of ACOLITE with the selected bio-optical algorithm shows the best performance on match-up data, with 27% MAPD for MSI. An example of application of this algorithm is provided along Vietnamese coastal water. For that purpose, the selected algorithm was applied to a set of co-located MSI and OLI images over worldwide coastal locations. to derive a linear correction that converts acdom(412) Sentinel-2 outputs to Landsat-8, enabling a seamless combination of both products, even though only slight differences have been observed between the MSI and OLI products over co-located images.

*Sơn Nguyễn Vũ, Laboratoire d’Océanologie et de Geosciences, Université du Littoral Côte d’Opale, Université de Lille, CNRS, IRD, UMR 8187, LOG

Hubert Loisel, Laboratoire d’Océanologie et de Geosciences, Université du Littoral Côte d’Opale, Université de Lille, CNRS, IRD, UMR 8187, LOG; Vietnam Academy of Science and Technology, Space Technology Institute; LOTUS, Vietnam Academy of Science and Technology, University of Science and Technology of Hanoi

Lan Tran Dinh, Vietnam Academy of Science and Technology, Institute of Marine Environment and Resources

Xavier Meriaux, Laboratoire d’Océanologie et de Geosciences, Université du Littoral Côte d’Opale, Université de Lille, CNRS, IRD, UMR 8187, LOG

Dat Dinh Ngoc, Laboratoire d’Océanologie et de Geosciences, Université du Littoral Côte d’Opale, Université de Lille, CNRS, IRD, UMR 8187, LOG; Vietnam Academy of Science and Technology, Space Technology Institute; LOTUS, Vietnam Academy of Science and Technology, University of Science and Technology of Hanoi

Manh Duy Tran, Laboratoire d’Océanologie et de Geosciences, Université du Littoral Côte d’Opale, Université de Lille, CNRS, IRD, UMR 8187, LOG

Daniel S.F. Jorge, Laboratoire d’Océanologie et de Geosciences, Université du Littoral Côte d’Opale, Université de Lille, CNRS, IRD, UMR 8187, LOG

Vincent Vantrepotte, Laboratoire d’Océanologie et de Geosciences, Université du Littoral Côte d’Opale, Université de Lille, CNRS, IRD, UMR 8187, LOG; Vietnam Academy of Science and Technology, Space Technology Institute; LOTUS, Vietnam Academy of Science and Technology, University of Science and Technology of Hanoi