Remote-sensing reflectance of turbid sediment-dominated waters Reduction of sediment type variations and changing illumination conditions effects by use of reflectance ratios

Abstract

Variations of sediment type (grain size and refractive index) and changing illumination conditions affect the reflectance signal of coastal waters and limit the accuracy of sediment-concentration estimations from remote-sensing measurements. These effects are analyzed from numerous in situ remote-sensing measurements carried out in the Gironde and Loire Estuaries and then reduced and partly eliminated when reflectance ratios between the near infrared and the visible are considered. These ratios showed high correlation with the sediment concentration. On the basis of the obtained relationships, performing correspondence functions were established that allow an accurate estimation of suspended sediments in the estuaries from Système Probatoire d'Observation de la Terre, Landsat, and Sea-Viewing Wide Field-of-View Sensor data, independently of the date of acquisition.

Optical characterisation of suspended particles in the Mackenzie River plume (Canadian Arctic Ocean) and implications for ocean colour remote sensing

“…λ NIR = 800 or 850 nm) and visible (e.g. λ VIS = 550 or 650 nm) spectral regions (Doxaran et al, 2002(Doxaran et al, , 2003(Doxaran et al, , 2006. Considering the nearinfrared spectral region is required in such waters where the R rs signal tends to saturate at visible wavebands (Doxaran et al, 2002).…”

Assessment of Total Suspended Sediment Distribution under Varying Tidal Conditions in Deep Bay: Initial Results from HJ-1A/1B Satellite CCD Images

“…Figure 5 shows the regression relationships between in-situ TSS and Rrs2, Rrs3 and Rrs3/Rrs2. Among these regressions, the band-ratio exponent algorithm showed better performance than the single-band algorithm based on measures with a higher coefficient of determination (R 2 ) and lower MRE because the influence of sediment grain size and refractive index variations on the reflectance in satellite bands is reduced when considering reflectance ratios [55]. According to the spectral characteristics of turbid waters, bands from 500 to 700 nm are effective for the retrieval of TSS concentrations from Landsat, SPOT and HJ-1A/1B satellite CCD sensors [7,10,16,27].…”

A review on substances and processes relevant for optical remote sensing of extremely turbid marine areas, with a focus on the Wadden Sea

“…Algorithms to derive SPM at locations with such extreme high SPM concentrations are the one-band algorithm tuned for the Belgian coast Ruddick et al 2004), the ratio algorithms for the Gironde and Loire estuaries in France (Chl-a <5 g l ¡1 , SPM <30 to >2,000 mg l ¡1 , CDOM 0.05-0.26) (Doxaran et al 2003), and the regression algorithm for the Malaysian coastal waters around Penang (SPM maximum >250 mg l ¡1 ), which takes the speciWc optical properties of Chl-a and CDOM in account (Lim et al 2008). Miller andMcKee (2004) used Modis Terra (IOCCG 2009) with a ground resolution of 250 £ 250 m to develop their SPM ratio algorithm in the complex waters of the northern Gulf of Mexico (US), which is especially useful in narrow water bodies of estuaries or the channels between tidal Xats.…”