Horizon 1 1 17 ACL : Articles dans des revues avec comité de lecture répertoriées par l'AERES Remote Sensing art. 45 [23 p.] chlorophyll-a concentration MODerate resolution Imaging Spectroradiometer (MODIS) ocean color remote sensing statistical algorithm oligotrophic waters New Caledonia coral lagoon NOUVELLE CALEDONIE PACIFIQUE 2016 fdi:010066220 ENG Remote Sensing 2072-4292 ISI:000369494500026 1 10.3390/rs8010045 https://www.documentation.ird.fr/hor/fdi:010066220 https://horizon.documentation.ird.fr/exl-doc/pleins_textes/divers16-03/010066220.pdf 8 Horizon (IRD) Spatial and temporal dynamics of phytoplankton biomass and water turbidity can provide crucial information about the function, health and vulnerability of lagoon ecosystems (coral reefs, sea grasses, etc.). A statistical algorithm is proposed to estimate chlorophyll-a concentration ([chl-a]) in optically complex waters of the New Caledonian lagoon from MODIS-derived remote-sensing reflectance (R-rs). The algorithm is developed via supervised learning on match-ups gathered from 2002 to 2010. The best performance is obtained by combining two models, selected according to the ratio of R-rs in spectral bands centered on 488 and 555 nm: a log-linear model for low [chl-a] (AFLC) and a support vector machine (SVM) model or a classic model (OC3) for high [chl-a]. The log-linear model is developed based on SVM regression analysis. This approach outperforms the classical OC3 approach, especially in shallow waters, with a root mean squared error 30% lower. The proposed algorithm enables more accurate assessments of [chl-a] and its variability in this typical oligo- to meso-trophic tropical lagoon, from shallow coastal waters and nearby reefs to deeper waters and in the open ocean. 126 ; 036 ; 020 UR235 / UR228 / UR065