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Optical Algorithms at Satellite Wavelengths for Total Suspended Matter in Tropical Coastal Waters
IRD, BP A5, 98848 Nouméa Cedex, New Caledonia
LEGOS/OMP, Université de Toulouse, UMR 5566, 14 avenue Edouard Belin, 31400 Toulouse, France
Laboratoire d’Océanographie Physique et de Biogéochimie, Université Aix Marseille, Centre d’Océanologie de Marseille, Luminy, 13288 Marseille cedex 09, France
Université Pierre et Marie Curie - Paris 6, CNRS, UMR 7621, Avenue Fontaulé, BP44, F-66650 Banyuls-sur-Mer, France
Université de Bordeaux, CNRS, UMR 5805, Bordeaux, F-33000, France
Centro de Estudios Ambientales de Cienfuegos, 5 CP 59 350 Ciudad Nuclear, Cienfuegos, Cuba
* Author to whom correspondence should be addressed.
Received: 4 June 2008; in revised form: 17 June 2008 / Accepted: 6 July 2008 / Published: 10 July 2008
Abstract: Is it possible to derive accurately Total Suspended Matter concentration or its proxy, turbidity, from remote sensing data in tropical coastal lagoon waters? To investigate this question, hyperspectral remote sensing reflectance, turbidity and chlorophyll pigment concentration were measured in three coral reef lagoons. The three sites enabled us to get data over very diverse environments: oligotrophic and sediment-poor waters in the southwest lagoon of New Caledonia, eutrophic waters in the Cienfuegos Bay (Cuba), and sediment-rich waters in the Laucala Bay (Fiji). In this paper, optical algorithms for turbidity are presented per site based on 113 stations in New Caledonia, 24 stations in Cuba and 56 stations in Fiji. Empirical algorithms are tested at satellite wavebands useful to coastal applications. Global algorithms are also derived for the merged data set (193 stations). The performances of global and local regression algorithms are compared. The best one-band algorithms on all the measurements are obtained at 681 nm using either a polynomial or a power model. The best two-band algorithms are obtained with R412/R620, R443/R670 and R510/R681. Two three-band algorithms based on Rrs620.Rrs681/Rrs412 and Rrs620.Rrs681/Rrs510 also give fair regression statistics. Finally, we propose a global algorithm based on one or three bands: turbidity is first calculated from Rrs681 and then, if < 1 FTU, it is recalculated using an algorithm based on Rrs620.Rrs681/Rrs412. On our data set, this algorithm is suitable for the 0.2-25 FTU turbidity range and for the three sites sampled (mean bias: 3.6 %, rms: 35%, mean quadratic error: 1.4 FTU). This shows that defining global empirical turbidity algorithms in tropical coastal waters is at reach.
Keywords: Ocean color; remote sensing; sediment transport; suspended matter; turbidity; New Caledonia; Cuba; Fiji.
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Ouillon, S.; Douillet, P.; Petrenko, A.; Neveux, J.; Dupouy, C.; Froidefond, J.-M.; Andréfouët, S.; Muñoz-Caravaca, A. Optical Algorithms at Satellite Wavelengths for Total Suspended Matter in Tropical Coastal Waters. Sensors 2008, 8, 4165-4185.
Ouillon S, Douillet P, Petrenko A, Neveux J, Dupouy C, Froidefond J-M, Andréfouët S, Muñoz-Caravaca A. Optical Algorithms at Satellite Wavelengths for Total Suspended Matter in Tropical Coastal Waters. Sensors. 2008; 8(7):4165-4185.
Ouillon, Sylvain; Douillet, Pascal; Petrenko, Anne; Neveux, Jacques; Dupouy, Cécile; Froidefond, Jean-Marie; Andréfouët, Serge; Muñoz-Caravaca, Alain. 2008. "Optical Algorithms at Satellite Wavelengths for Total Suspended Matter in Tropical Coastal Waters." Sensors 8, no. 7: 4165-4185.