Martinez Jean-Michel, Espinoza-Villar R., Armijos E., Moreira L. S. (2015). The optical properties of river and floodplain waters in the Amazon River Basin : implications for satellite-based measurements of suspended particulate matter. Journal of Geophysical Research. Earth Surface, 120 (7), p. 1274-1287. ISSN 2169-9003.
Titre du document
The optical properties of river and floodplain waters in the Amazon River Basin : implications for satellite-based measurements of suspended particulate matter
Martinez Jean-Michel, Espinoza-Villar R., Armijos E., Moreira L. S.
Source
Journal of Geophysical Research. Earth Surface, 2015,
120 (7), p. 1274-1287 ISSN 2169-9003
Satellite images can now be used to assess river sediment discharge, and systematic studies over rivers and lakes are required to support such applications and document the variability of inland water optical properties at the watershed scale. The optical properties of the Amazon Basin waters were analyzed from in situ measurements of the remote sensing reflectance (R-rs) at 279 stations and downwelling diffuse attenuation coefficients (K-d) at 133 stations. Measurements of the apparent optical properties, suspended particulate matter (SPM) contents, and characteristics and colored dissolved organic matter (CDOM) absorption spectra were performed during 16 cruises along the main Amazonian Rivers draining the Andes and for some tributaries. Surface-suspended sediment granulometry and mineralogy showed a stable distribution at the catchment scale, even over large distances and between tributaries. The particle number-size distribution was best described using a segmented distribution with a slope of 2.2 for the fine range (1-15 mu m), and the CDOM absorption coefficient at 440nm varied from 1.8 to 7.9m(-1). Overall, both R-rs and K-d were strongly correlated with SPM, although strong CDOM absorption limited the use of the blue spectrum. Reflectance saturation from blue to red was observed at approximately 100gm(-3), whereas the near-infrared (NIR) wavelength enabled the monitoring of the full SPM range (5-620gm(-3)). In contrast, K-d showed no saturation for SPM from green to NIR, and a linear model was calculated. The use of the reflectance ratio was investigated and shown to improve the suspended sediment concentration retrieval performance.
Plan de classement
Hydrologie [062]
;
Télédétection [126]
Description Géographique
AMAZONE BASSIN ; AMAZONIE ; PEROU ; BRESIL ; SOLIMOES COURS D'EAU ; MADEIRA COURS D'EAU
