Variability of apparent and inherent optical properties of sediment-laden waters in large river basins &#x2013; lessons from in situ measurements and bio-optical modeling

Sylvain Pinet; Jean-Michel Martinez; Sylvain Ouillon; Bruno Lartiges; Raul Espinoza Villar

doi:10.1364/OE.25.00A283

Optics Express
Vol. 25,
Issue 8,
pp. A283-A310
(2017)
•https://doi.org/10.1364/OE.25.00A283

Variability of apparent and inherent optical properties of sediment-laden waters in large river basins – lessons from in situ measurements and bio-optical modeling

Sylvain Pinet, Jean-Michel Martinez, Sylvain Ouillon, Bruno Lartiges, and Raul Espinoza Villar

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Sylvain Pinet, Jean-Michel Martinez, Sylvain Ouillon, Bruno Lartiges, and Raul Espinoza Villar, "Variability of apparent and inherent optical properties of sediment-laden waters in large river basins – lessons from in situ measurements and bio-optical modeling," Opt. Express 25, A283-A310 (2017)

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Table of Contents Category
- Remote Sensing and Sensors
Optics & Photonics Topics
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The topics in this list come from the Optics and Photonics Topics applied to this article.
Previously assigned OCIS codes
- Water (010.7340)
- Radiative transfer (010.5620)
- Radiometry (010.5630)
- Particles (350.4990)

About this Article
History
- Original Manuscript: November 1, 2016
- Revised Manuscript: January 16, 2017
- Manuscript Accepted: January 16, 2017
- Published: March 9, 2017

Abstract

We investigated the relationships between inherent and apparent optical properties (IOP and AOP, respectively) and suspended sediment concentrations (SSC) in the main Amazonian river waters. In situ measurements of SSC, remote sensing reflectance ( $R_{r s}$ ), the diffuse light attenuation coefficient ( $K_{d}$ ) and the total and non-algal particle (NAP) absorption coefficients ( $a_{T O T}$ and $a_{N A P}$ , respectively) were conducted during three sampling trips along different streams of the Amazon River catchment (104 stations). The size distribution and chemical characteristics of the suspended sediment were also determined for 85 stations. We show that the particle size distribution (PSD) in the river water is best described by a segmented Junge power law distribution with a smaller slope value for the smallest particles ( $J_{1}$ = 2.4) and a larger slope value ( $J_{2}$ = 4.1) for the largest particles (> 10 µm). A strong relationship was found between AOPs and IOPs and SSC when the entire data set was considered. However, for the Madeira River, the primary Amazon River tributary in terms of suspended sediment discharge, a significant dispersion was detected for the $R_{r s}$ – SSC relationship but not for the $K_{d}$ – SSC relationship. This dispersion has been shown by a previous study, using MODIS data, to display a seasonal pattern, which we investigated in this study using Mie modeling calibrated with suspended sediment characteristics. In the Madeira River, suspended sediment had a finer distribution size and a different mineralogy (e.g., a greater smectite content and a lower kaolinite content) during the rising water stage. Spectral variations of the imaginary part $n^{'} (λ)$ of the refraction index also showed significant differences during the rising water stage. In contrast, other streams of the Amazon basin had very stable properties with respect to granulometry and mineralogy. Model simulations made possible to reproduce both field and satellite observations, showing that the $R_{r s}$ hysteresis observed in the Madeira River in the near infrared was mainly due to $n^{'} (λ)$ seasonal variations, leading to a decrease of absorption during the rising water stage. $K_{d}$ was shown to remain stable because of its strong dependency on scattering processes. The model was used to further understand how suspended sediment size distribution and refraction index drive the IOPs in large rivers: $n^{'} (λ)$ variations were shown to control primarily the reflectance variability; $R_{r s}$ (850) presented limited variations as a function of PSD in the range typical of large rivers ( $J_{1}$ < 3) although it remained sensitive to particle mineralogical composition; $R_{r s}$ (670) showed the opposite behavior with a higher sensitivity to PSD variation for coarser PSD. Finally, we demonstrate that the use of the $R_{r s}$ ratio between the red and infrared channels allowed a reduction of the $R_{r s}$ sensitivity in all cases, by an average of 50% with respect to changes in the mineral composition or size distribution of suspended sediment. In particular, the $R_{r s}$ ratio varied by less than 5% for PSD representative of surface river waters.

1. Introduction

The monitoring of erosion, sediment transport and deposition processes in a catchment is crucial for addressing a large variety of topics such as geomorphology [1], the dissemination of nutrients and contaminants in the environment [2], river navigability and river bank and coastal erosion in the context of land use and climate change [3]. In large river basins, the issue of sediment transport is of particular relevance both at a regional and global scale because these systems represent the major source of most of lithogenic and anthropogenic elements in the ocean [4,5]. Paradoxically, these basins are often poorly equipped with hydrological stations in comparison with their surface of drainage [6]. Overcoming this problem could be accomplished by in an increase in the use of spaceborne remote sensing. In recent years, an increasing number of studies have mapped suspended sediment concentrations (SSC – see the acronyms in Table 1) using satellite ‘water color’ data [7–15]. Although some works investigated water quality in lakes [16–19], wetlands [20] or estuaries [21–24], most applications of remote sensing have been dedicated to coastal waters (i.e., case 2 waters [25]). Retrieval algorithms for SSC, the diffuse attenuation coefficient $K_{d}$ and the Secchi disk depth from reflectance data have been developed and applied in studies of the inherent optical properties of waters, mainly for case 2 waters, either experimentally or via modeling [26–31].

Table 1. List of acronyms and symbols.

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Conversely, there is an important lack of knowledge on the optical properties of river waters. More specifically, little is known about how the physical characteristics of the suspended sediment in continental waters drive their optical properties. Thus, concurrent measurements of suspended sediment optical properties and physical characteristics including particle size distribution (PSD) and mineralogy are needed. However, experimental data acquired in river waters are scarce and previous modeling efforts have been based upon parameters suited to oceanic conditions, such as the fine particle distribution (e.g., considering a Junge size distribution of slope 4) and have used a generic suspended sediment mineral composition that was not representative of any specific catchments. There is a need to measure and jointly interpret suspended sediment optical properties and their physical characteristics, including PSD and mineralogy, to understand how remote sensing reflectance can be robustly linked to suspended sediment concentration in rivers. Such a full characterization would support realistic modeling studies and pave the way for the development of robust retrieval algorithms for river sediment discharge monitoring.

In this study, we present a detailed water color study for river waters that encompasses field measurements of the apparent optical properties (AOPs) and inherent optical properties (IOPs), and a characterization of both the mineralogy and PSD of the suspended particles. The study was performed in the Amazon River basin and focused on the Madeira River, benefitting from previous studies that showed the relative stability of optical properties of the Amazon Basin river waters, except for the Madeira River. In this sub-catchment, Villar et al. [32] used field spectroradiometry and MODIS images to show that reflectance had a hysteretic relationship with SSC during the annual hydrological cycle. They showed that the seasonal variability of the reflectance could be efficiently accounted for by using a band ratio between the red and infra-red wavelengths. New data were collected along the Madeira River to support the detailed modeling of the seasonal variation of the IOPs and to understand how the physical and chemical characteristics control the optical properties. Optical modeling was further used to understand the contribution of the different particle size classes and the sensitivity of the IOPs/AOPs to the sediment type and size distribution. Finally, the use of the band ratio to reduce the impact of the characteristics of the suspended sediment on the reflectance was investigated to understand its advantages when using satellite data to map the SSC over rivers.

2. Materials and methods

2.1 Study area

The Amazon River basin encompasses 6.1 x 10⁶ km² [33], representing the largest watershed in the world with respect to water discharge (on average, 208 x 10³ m³ s⁻¹ [34]), and is a major contributor of sediments input to the ocean, with a mean inter-annual sediment discharge of 800 x 10⁶ t yr⁻¹ as assessed at the Óbidos gauging station [35]. Most of the Amazon River basin experiences a dry season from April to September and a rainy season from November to March. Accordingly, the main Amazonian rivers draining the Andes have a unique low-flow period from September to December, a rising water period from December to March, and a flood peak from February to June, depending on their position within the catchment [36–39]. Among the dense and complex network of streams and lakes that form the Amazon basin, the Solimões and the Madeira Rivers each contribute almost 50% to the total Amazon River sediment discharge to the ocean [40]. The Solimões River is the main stream of the upper Amazon River flowing from the Central Andes in Peru and Ecuador [Fig. 1]. The Madeira River drains the southern Andes, mainly in Bolivia. The confluence of the Madeira River with the Amazon River occurs approximately 1000 km upstream from the Atlantic Ocean. The Madeira River drains an area of more than 1.4 x 10⁶ km² and has a mean annual water discharge of 32,000 m³ s⁻¹ [41]. The sediments transported by the Madeira River mainly originate from erosion in the Andes and are principally composed of clays [42].

Fig. 1 Map of the Amazon River basin and of the Solimões and Madeira River tributaries (after Villar et al. [32]).

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2.2 Sampling

Three different sampling trips were organized to collect data along the Solimões, Madeira and Amazon Rivers and their main tributaries in March 2013, April 2014 and December 2014. During all these sampling trips, the optical, physical and bio-geochemical variables were measured and the contrasting water types exhibited a large variability in the different parameters sampled (Table 2).

Table 2. Ranges of the parameters measured at the 104 stations during the three field surveys.

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Water samples were collected at each station from a boat on the river water surface [0-30 cm] and at different depths. At the water surface, the parameters measured included SSC, POC, PSD, mineralogy, $R_{r s}$ , $K_{d}$ , $a_{N A P}$ , and $a_{C D O M}$ . Within the water column, the parameters measured included SSC, POC, PSD, mineralogy, $a_{N A P}$ , and $a_{C D O M}$ .

PSDs were determined at the Brazilian Geological Service (CPRM) with a Malvern Mastersizer 2000 Laser Diffraction grain size meter for materials ranging in size from 0.95 µm to 500 µm. The general shape of the PSD is often described by a power-law function, also called a Junge size distribution [43,44], as follows:

N (D) = K \times D^{- J} .

where $N$ corresponds to the number of particles of diameter $D$ , K is the concentration of particles and J is the slope of the distribution, also called Junge’s exponent. For oceanic waters, J is often considered to vary around a mean value of 4 [45] and may also vary in coastal waters [46]. However, for continental waters, J values around 4 may be inappropriate to describe the full PSD [47,48], and other values must be used depending on the aggregation state, in particular towards larger size particles, thus requiring lower values of J. Following a proposal by Mobley [49] and Martinez et al. [50], we also considered two distinct Junge coefficients ( $J_{1}$ and $J_{2}$ ) in two different particle size ranges to better fit the observed PSDs.

Water samples were filtered using a 0.45 µm cellulose acetate filter (Millipore) that had been previously dried for 24 h at 60°C and weighed. After filtration, the filters were dried for 24 h at 60°C and weighed again to determine the SSC. The POC values were assessed from water samples that were filtered under low vacuum on a 0.7 µm Millipore membrane using an all-glass filtering device. The POC was analyzed in the laboratory according to the protocol described in Moreira-Turcq et al. [51].

Suspended sediment results from the mineralogical assemblage driven by the catchment pedology, erosion processes and hydraulic transport within the stream channel. As determined by the refraction index, the mineralogy is the principal determinant of the sediment optical properties, along with their size distribution [52]. For a suspended sediment mineralogical determination, at some stations, a volume of water was sampled (from 1 ml for highly turbid waters up to 10 ml for clearest waters), deposited on a 0.4 µm polycarbonate membrane, then analyzed using Scanning Electron Microscopy (SEM) in the backscattered imaging mode coupled with Energy-Dispersive X-ray Spectroscopy. SEM generates a beam of electrons that scans the filter sample surface allowing each individual particles to be resolved, and the emitted X-ray spectra depend on the chemical nature of the sample, making it possible to determine each chemical element present on a particle surface [53]. For the mineralogical determination, the elementary contents in sodium (Na), magnesium (Mg), aluminum (Al), silicon (Si), potassium (K), calcium (Ca), titanium (Ti), and iron (Fe) were computed and analyzed by the use of an unsupervised classification known as Partitioning Around Medoids (PAM) [54]. The PAM method partitions a data set into k clusters around medoids, where k is specified in advance. The group classification was also investigated in order to obtain the best coherence for each group while maintaining a reasonable number of groups. To obtain a statistically robust classification, we also used the supervised learning Random Forest classification algorithm [55] and compared the results of the two methods. These classification processes allowed us to estimate the mineralogical assemblage of a test sample, and to test the robustness of the classification by comparing the two techniques [56]. The confusion matrix showed an error rate lower than 4% between the two classifications schemes for every tests (>20 times). The POC and SPM concentration values are means of 2 and 3 replicates, respectively.

The PSD measurements are means of 5 replicates for each particle size class. The protocol of mineralogical determination involves an analysis of 15 000 individual particles on average per station using Scanning Electron Microscopy.

2.3 Radiometric data

AOPs measurements were made at each station with TriOS RAMSES hyperspectral radiance and irradiance sensors (TriOS Mess- und Datentechnik GmbH, Rastede, Germany), allowing measurements ranging from 320 nm up to 950 nm with a 2.5 nm spectral resolution.

The above-water surface remote sensing reflectance, $R_{r s}$ , is defined as the ratio between the water-leaving radiance $L_{w} (0^{+}, θ, ϕ, λ)$ and the downwelling irradiance $E_{d} (0^{+}, ϕ, λ)$ [57]:

R_{r s} (0^{+}, θ, ϕ, λ) = \frac{L_{w} (0^{+}, θ, ϕ, λ)}{E_{d} (0^{+}, ϕ, λ)} .

where $0^{+}$ indicates above water; $θ$ and $ϕ$ define the polar and azimuthal directions, respectively; and $λ$ is the wavelength. Hereafter, for simplification, the dependence of radiometric parameters to $0^{+}$ , $θ$ and $ϕ$ has been omitted. Because the upwelling radiance, $L_{u}$ , is the sum of the leaving-water radiance $L_{w} (0^{+})$ and of the sky-reflected radiance at the water surface, $R_{r s}$ is evaluated using the following equation:

R_{r s} = \frac{L_{u} (λ) - ρ \times L_{d} (λ)}{E_{d} (λ)} .

where the proportionality coefficient $ρ$ is the skyglint correction factor. A value of $ρ$ = 0.028 is commonly used for surfaces presenting low rugosity [57]. The radiance sensors were pointing the sky and the water surface for $L_{d} (0^{+})$ and $L_{u} (0^{+})$ , respectively, with an angle $θ = 40 °$ from the nadir and with an azimuth angle $ϕ =$ 135° relatively to the sun, while the irradiance sensor was fixed vertically, as suggested by Mobley [57]. The measurements were taken for a minimum of 10 minutes when the sky conditions were as clear as possible, then the median spectrum was selected to avoid the influence of possible passing clouds.

A series of in-water downwelling irradiances $(E_{d})$ vertical profiles were acquired at discrete depths in rapid succession within the euphotic layer at the river surface, usually after the $R_{r s}$ measurement. The diffuse attenuation coefficients for the downward irradiance $K_{d}$ were calculated from the slope of the semi-log plot of the downwelling irradiance versus depth. The depth over which the attenuation coefficient is calculated has been defined as the lowest depth where downwelling irradiance in the blue and NIR wavelengths (e.g., the region of the spectrum where light absorption is the strongest) show significant values. Thus, the $K_{d}$ was always assessed over layer depths varying between 50 cm (strongest SPM level) and 3 m. Log $(E_{d})$ was then found to vary linearly with depth.

The Online hyperSpectral integrating Cavity Absorption meteR (OSCAR) spectrophotometer was used to determine the dissolved and the total absorption coefficients ( $a_{C D O M}$ and $a_{T O T}$ , respectively) from 360 to 750 nm. This spectrophotometer includes a system based on the principle of a Point Source Integrating Cavity Absorption Meter (PSICAM) [58–64], with a spherical cavity of 8 cm diameter. The OSCAR sensor is equipped with inlets and outlets, allowing a water flow in the sensor cavity. The sensor corresponds to a miniature spectrometer, as it has been used by Wollschläger et al. [62,63]. During the field sampling campaigns, OSCAR calibration was performed daily using a reference solution of nigrosine. The spectral absorption coefficient of the nigrosine solution was previously measured in laboratory against purified water as a reference using a spectrophotometer (Secoman Uvi light XT5, 10 cm pathlength). The water sample was first passed through the sensor cavity using a peristaltic pump and $a_{T O T A L}$ was calculated by averaging absorption spectra recorded during 5 minutes. The Oscar sensor was rinsed after each measurement with Milli-Q water. For $a_{C D O M}$ , 500 ml of the water sample were filtered through 0.7 µm Millipore glass-fiber filter. Sensitivity of $a_{C D O M}$ to membrane porosity have been tested using filters from 0.2 to 0.7 µm, showing that the results varies less than 5% on average at all wavelengths. Most of the organic matter in river water is in the finest fraction range, which is much smaller than the 0.45 µm filter porosity [65,66]. For both $a_{T O T A L}$ and $a_{C D O M}$ , after the suppression of every air bubbles in the sensor, we launched the acquisition for 5 mn (about 20 measurements). Results were then post-treated: the median spectrum was kept as the final value of the sample absorption.

Because the phytoplankton concentration is weak in relation to the mineral particle concentration in the Amazonian rivers [50], the Non-Algal Particle (NAP) absorption coefficients ( $a_{N A P}$ ) were simply calculated as follows:

a_{N A P} = a_{T O T} - a_{C D O M} .

The absorption spectra $a_{N A P}$ and $a_{C D O M}$ originally incremented with a 1.7 nm step were interpolated linearly at a 1 nm wavelength resolution. The shape and intensity of the absorption spectra are absolutely unchanged. Then, we extrapolated the absorption spectra up to 850 nm using regressions following an exponential relationship and calculated on the range [400-700 nm].

2.4 Modeling

2.4.1 Theoretical background

The inherent and apparent optical properties of turbid waters were computed using the Meerhoff Mie Program (MMP) [67], based on the Mie scattering theory developed for homogenous spherical particles (usually called Mie scattering) [68]. Despite the natural diversity of particle shapes, the permanent turbulence of the riverine waters during the sampling campaigns leads to randomly oriented particles in the water and allowed us to accept the hypothesis of spherical particles, assuming that gains and losses compensate for each other. The MMP was used to calculate the optical properties either for single particles of radius r or for populations of particles with log-normal or power-law PSDs. We first computed the optical properties for single particles with a diameter corresponding to all size classes considered by the grain size meter. We then calculated the optical properties for the entire population with the corresponding PSD using the following formulations [68,69]:

C_{b} = \frac{\int_{D_{m i n}}^{D_{m a x}} Q_{b} (λ, D, n) (\frac{π D^{2}}{4}) N (D) d D}{\int_{D_{m i n}}^{D_{m a x}} N (D) d D},

C_{b b} = \frac{\int_{D_{m i n}}^{D_{m a x}} Q_{b b} (λ, D, n) (\frac{π D^{2}}{4}) N (D) d D}{\int_{D_{m i n}}^{D_{m a x}} N (D) d D},

C_{b b} = \frac{\int_{D_{m i n}}^{D_{m a x}} Q_{b b} (λ, D, n) (\frac{π D^{2}}{4}) N (D) d D}{\int_{D_{m i n}}^{D_{m a x}} N (D) d D},

C_{a} = \frac{\int_{D_{m i n}}^{D_{m a x}} Q_{a} (λ, D, n) (\frac{π D^{2}}{4}) N (D) d D}{\int_{D_{m i n}}^{D_{m a x}} N (D) d D},

G = \frac{π}{4} \frac{\int_{D_{m i n}}^{D_{m a x}} D ² N (D) d D}{\int_{D_{m i n}}^{D_{m a x}} N (D) d D},

{\bar{Q}}_{b} = \frac{C_{b}}{G},

{\bar{Q}}_{b b} = \frac{C_{b b}}{G},

where ${\bar{Q}}_{b}$ is the scattering efficiency factor of the population of particles, $C_{b}$ the average scattering cross section and G is the average geometrical cross section. These efficiency factors enabled us to retrieve the mass-specific scattering, backscattering and absorption coefficients ( $a_{N A P}^{*}$ , $b_{N A P}^{*}$ and $b_{b N A P}^{*}$ respectively, in m² g⁻¹) [45]:

b_{N A P}^{*} = \frac{3 {\bar{Q}}_{b}}{2 ρ^{'}} \int_{D_{m i n}}^{D_{m a x}} N (D) D ² d D {(\int_{D_{m i n}}^{D_{m a x}} N (D) D^{3} d D)}^{- 1},

b_{b N A P}^{*} = \frac{3 {\bar{Q}}_{b b}}{2 ρ^{'}} \int_{D_{m i n}}^{D_{m a x}} N (D) D ² d D {(\int_{D_{m i n}}^{D_{m a x}} N (D) D^{3} d D)}^{- 1},

a_{N A P}^{*} = \frac{3 {\bar{Q}}_{a}}{2 ρ^{'}} \int_{D_{m i n}}^{D_{m a x}} N (D) D ² d D {(\int_{D_{m i n}}^{D_{m a x}} N (D) D^{3} d D)}^{- 1} .

where $ρ^{'}$ is the density of the mineral particles and specific $b_{N A P}^{*}$ , $b_{b N A P}^{*}$ , $a_{N A P}^{*}$ are equal to the ratio between $b_{N A P}$ , $b_{b N A P}$ , $a_{N A P}$ , respectively and SSC.

These coefficients allowed us to calculate the apparent optical properties $R (0^{-})$ , $K_{d}$ , and $R_{r s}$ via the equations of Jerlov [70], Kirk [71] and Gordon et al. [72] yielding, respectively:

R (0^{-}) = f^{'} \times \frac{b_{b T O T}}{a_{T O T} + b_{b T O T}},

K_{d} = \sqrt{a_{T O T}^{2} + (G' \times a_{T O T} \times b_{T O T})},

R_{r s} = \frac{t}{n_{w a t e r} ²} \times \frac{f'}{Q} \times \frac{b_{b T O T}}{a_{T O T} + b_{b T O T}} .

where $f'$ is a factor that depends on the light conditions and the water type, and is typically equal to 0.33 [25]; $G'$ is a coefficient that has been shown to vary from 0.233 to 0.264 and that can be defined as the relative contribution of the scattering to the vertical attenuation of the irradiance [73]; the ratio $t / n_{w a t e r} ²$ is equal to 0.546 and stands for the air-water Fresnel reflection and refraction effects [74]; the ratio $f^{'} / Q$ can be estimated to be equal to 0.13 in turbid waters, Q representing the anisotropy factor [75]; the $b_{T O T}$ , $a_{T O T}$ and $b_{b T O T}$ coefficients represent the total scattering, absorption and backscattering coefficients, respectively, defined as follows:

b_{T O T} = b_{W} + b_{N A P} + b_{C D O M} + b_{P H Y},

b_{b T O T} = b_{b W} + b_{b N A P} + b_{b C D O M} + b_{b P H Y},

a_{T O T} = a_{W} + a_{N A P} + a_{C D O M} + a_{P H Y} .

where subscripts W stands for water and PHY for phytoplankton.

It is possible to reduce these expressions for the turbid waters of the Amazonian basin because of the low concentrations of phytoplankton [51], and the spectral domination of scattering by terrigenous particles and backscattering coefficients compared to those for water and CDOM. Thus, we obtain the following:

R (0^{-}) = f^{'} \times \frac{b_{b N A P}}{a_{W} + a_{N A P} + a_{C D O M} + b_{b N A P}},

K_{d} = \sqrt{(a_{W} + a_{N A P} + a_{C D O M}) ² + G' \times (a_{W} + a_{N A P} + a_{C D O M}) \times b_{N A P})},

R_{r s} = \frac{t}{n_{w a t e r} ²} \times \frac{f^{'}}{Q} \times \frac{b_{b N A P}}{a_{W} + a_{N A P} + a_{C D O M} + b_{b N A P}} .

2.4.2 Model parametrization

Optical modeling was used to understand the seasonal variability of the AOPs and IOPs as a function of the SSC on the Madeira River (Fig. 2). Inputs were determined from field measurements or from realistic ranges of values for continental waters. At each station, the real part of the refraction index was calculated as the integration of the percentage of each mineral with the corresponding refraction indices given by Kerr [76] and of the POC with a typical mean value of n = 1.05 for organic matter [30,48,77]. For the imaginary part $n^{'} (λ)$ of the refraction index, very little data are available in the literature. In this study, we calculated $n^{'} (λ)$ such that the modeled $a_{N A P}$ fits to the measured $a_{N A P}$ following the methodology proposed by Kobayashi et al. [11]. At every wavelength, values of $n^{'} (λ)$ ranging from 0 to 0.05 by steps of 5 x 10⁻⁵ were tested and the associated errors between the measured and simulated $a_{N A P}$ were calculated to assess the best $n^{'} (λ)$ parameterization. We then performed a series of simulations with n ranges that encompassed the values measured in the field. The spectral variations of the imaginary part of the refraction index $n^{'} (λ)$ , strongly related to $a_{N A P}$ [78], were estimated at visible and infra-red wavelengths by scanning a large range of values. The retained value was the one that produced the smallest difference between the simulated and measured $a_{N A P}$ . The Malvern grain size meter provided the total volume distribution of the particles, allowing us to calculate a relative number of particles for each size class between 0.27 µm and 240 µm (i.e., D_min and D_max, respectively), then to generate Junge’s exponent () for each station.

Fig. 2 Data involved in the modeling process (inputs and outputs), or used to compared the simulated optical properties with in situ measurements and satellite data. Model calibration was based on field samplings (PSD, mineralogy and light absorption coefficient). Satellite data were retrieved from MODIS image time series following Villar et al. [32] in order to display the $R_{r s}$ seasonal hysteresis as a function of SPM concentration, and to compare the reflectance estimates with the modeling outputs. They were not used for modeling calibration.

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3. Results

3.1 Grain size distribution

Figure 3 shows the 85 PSDs measured during our three surveys in the Solimões River, Madeira River, Amazon River and their main tributaries (Table 3). Power-law regressions were fitted to the entire particle size range measured [0.95 – 500 µm] and for all of the samples. The residuals between the regressions and the measurements were the highest between 10 µm and 15 µm, exposing a gap between the field data and the power-law regressions for these size classes. We then calculated the Junge coefficients for particles smaller and larger than 10 µm to better fit the observed PSDs. The determination coefficients (r²) used to derive the segmented linear regressions were higher than 0.99, demonstrating a good fit of the observed PSDs for all size classes.

Fig. 3 Measured particle size distributions of 85 samples (grey curves): number of particles per µm³. The crosses represent a theoretical power law, the triangles represent a power-law regression on the entire data set, and the black lines represent power-law regressions for size ranges lower and greater than 10 µm.

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Table 3. Number (N_s) of optical and PSD measurements for each stream and average values of D₅₀, D₉₀ (in µm), and slopes of the PSDs (see Table 1 for symbols).

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Considering the entire data set, the average slope $J_{1}$ of the fine grain size range (from 1 to 10 µm) was 2.180 ± 0.056 and the average slope $J_{2}$ for the coarse range ( $J_{2}$ from 10 to 104 µm) was 3.856 ± 3 x 10⁻⁴, instead of J = 3.006 ± 0.455 representing a single regression. These results are in agreement with Martinez et al. [50] who found a slope of 2.22 for the fine material (from 1 to 15 µm) and of 4.56 for the coarser material (from 15 to 104 µm) for 39 water surface samples from different rivers across the Amazon River watershed.

Separately considering the PSDs for each river (Table 3), the Madeira River had average slopes of 2.443 and 4.054, respectively, for the finer and coarser size ranges ( $α$ = 0.093) and a median diameter of the suspended sediment (D₅₀ = 6.68 µm) significantly lower than in other tributaries. Furthermore, D₅₀ showed strong annual variation in the Madeira River, with a mean value of 8.16 µm during the high water stage (March 2013) and a value of 5.57 µm during the rising water period (December 2014), indicating a shift towards smaller sizes during the rising stage. These values are consistent with those estimated by Villar et al. [32] on a limited set of samples, who found D₅₀ values close to 5m for rising waters (November 2009) and 7-9 µm at flood peak (April 2010) in the Madeira River.

3.2 Mineralogy

SEM analyses were conducted on 17 water samples from the Solimões, Amazon and Madeira Rivers, and were based on 306 SEM images and more than 25,000 individually analyzed particles. A PAM classification was completed for 6366 particles from the field campaign of March 2013, resulting in the differentiation of 15 groups. Each of these groups was associated with a mineralogy based on the proportion of the main chemical elements. The mean correlation coefficient was greater than 92% for samples collected at the Solimões River stations taken two by two, and greater than 96% for samples collected at the Amazon River stations with a 1-year interval, demonstrating the stability of the mineralogical composition of the suspended sediment in those two rivers. For the Madeira River stations, the mineralogy retrieved from the SEM analysis of the samples collected in December 2014 had a correlation coefficient of 97%, but the samples were poorly correlated with those collected in March 2013 on the same river (55%). We detected a much higher kaolinite content in March 2013 (18%) than in all other stations analyzed by SEM (7% on average), while the smectite content was up to 24% for the Madeira River stations sampled in December 2014 (11% on average for other stations) [Fig. 4]. In all cases, iron oxides did not contribute over 2.5%.

Fig. 4 Mineralogy determined after SEM analysis for the Madeira River in March 2013 (left), and in December 2014 (right).

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3.3 Radiometry

Figure 5 shows the variation of $R_{r s}$ (850), the ratio R(850)/R(670), $K_{d}$ (670) and $a_{N A P}$ (550) as a function of the SSC at the 104 sampled stations. The measured AOPs and IOPs generally show good correlations with the SSC, with $K_{d}$ showing the highest correlation, exhibiting a linear relationship [Fig. 5(c)]. For the Madeira River stations, a significant dispersion was detected for $R_{r s}$ (850) [Fig. 5(a)] that did not appear with $K_{d}$ (670) or $a_{N A P}$ (550) [Fig. 5(c), 5(d)]. Such a high dispersion between the surface reflectance $R_{r s}$ (850) and the SSC on the Madeira River was described by Villar et al. [32] based on field radiometric measurements and MODIS data [Fig. 6]. This dispersion resulted from a seasonal dependence that led to high $R_{r s}$ (850) values during the rising water period (November to January) despite medium SSCs. For the rest of the hydrological cycle, a near linear trend was found between $R_{r s}$ (850) and the SSCs. Villar et al. [32] showed that this seasonal hysteresis could be attenuated by the use of a band ratio between the infra-red and red band channels. For our data set, we found that the $R_{r s}$ (850)/ $R_{r s}$ (670) band ratio significantly improved the regression accuracy (r² = 0.89 vs. 0.79) [Fig. 5(b) vs. Fig. 5(a)]. $K_{d}$ and $a_{N A P}$ do not show seasonal dependence, however the mean specific absorption coefficients for non-algal particles, $a_{N A P}^{*}$ , calculated from OSCAR measurements show differences between the rising water stage and the rest of the year on the Madeira River.

Fig. 5 Relationships between SSCs and optical properties: a) in situ $R_{r s}$ (850); b) band ratio between $R_{r s}$ (850) and $R_{r s}$ (670); c) in situ diffuse light attenuation coefficient $K_{d}$ (670); d) in situ non-algal particulate matter absorption coefficient $a_{N A P}$ (550).

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Fig. 6 Average monthly MODIS surface reflectances $R_{s}$ (850) for 2000-2011 as a function of SSC on the Madeira River at the Porto Velho gauging station as retrieved by Villar et al. [32]. The numbers indicate the month from January (1) to December (12).

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At 620 nm, $a_{N A P}^{*}$ was slightly higher in March 2013 (0.0081 m² g⁻¹) than in December 2014 (0.0072 m² g⁻¹). At 850 nm, the differences were greater: $a_{N A P}^{*}$ at the high water stage reached 1.81 x 10⁻³ m² g⁻¹, while its mean value for the rising water period was 7.8 x 10⁻⁴ m² g⁻¹. Variations of $a_{N A P}^{*}$ at 440 nm, from 0.021 m² g⁻¹ (Solimões River) to 0.031 m² g⁻¹ (Madeira river during rising stage) are towards the lower end of the range documented by Babin et al. [26] for non-algal particles in European coastal waters (0.033 – 0.067) or by Peng & Effler [79] (0.04 – 0.13). Our values are all also close to the one reported over various turbid waters such as in an alpine lake [80] with $a_{N A P}^{*}$ (440) = 0.08 m² g⁻¹ or for the Gironde River estuary [30] with $a_{N A P}^{*}$ (440) = 0.042 ± 0.017 m² g⁻¹. Ma et al. [81] reported for highly turbid inland waters of a tropical lake in China that $a_{N A P}^{*}$ (440) shows decreasing values with increasing SSC within the [0-150] g m⁻³ range, from 0.169 down to 0.043 m² g⁻¹. At 700 nm, $a_{N A P}^{*}$ varied from 0.0046 to 0.006 m² g⁻¹, which is also in the range reported by Doxaran et al. [30] (0.008 ± 0.004 m² g⁻¹). The spectral variations of $a_{N A P}^{*}$ fitted the pattern observed by Babin & Stramski [78], highlighting that $a_{N A P}^{*}$ at near infra-red (NIR) is less than 10% of $a_{N A P}^{*}$ (400).

3.4 Modeling

3.4.1 IOP variability during the hydrological cycle

Despite the differences in the mineralogy observed for the Madeira River between the rising water stage and the high water stage, the real part (n) of the refraction index varied within a very limited range, from 1.167 to 1.183. Spectral variations of $n^{'} (λ)$ were retrieved for the Madeira River at the high water stage (N = 4) and the rising water stage (N = 3) and for the Solimões River (N = 11), and compared to those obtained by Kobayashi et al. [11] in the Bangpankong River estuary [Fig. 7].

Fig. 7 Spectral variations of the imaginary part $n^{'}$ of the refraction index of the suspended particles. Data corresponding to Solimões River and Madeira River are mean values (standard deviations are represented by the error bars) obtained by mineralogical determination by SEM. Values extracted from Kobayashi et al. [11] and corresponding to the Bangpankong River estuary stand for the reference.

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Overall, the spectral variations of $n^{'} (λ)$ showed a negative exponential pattern, as found by Babin et al. [26], Kobayashi et al. [11], and Peng & Effler [79]. The $n^{'} (λ)$ values were very similar for the Madeira River at the high water stage ( $n^{'}$ (440) = 0.0022) and for the Solimões River for all hydrological periods ( $n^{'}$ (440) = 0.0021), with a spectral slope of −0.004 ± 0.0005 nm⁻¹ [Fig. 7]. However, the $n^{'} (λ)$ values ( $n^{'}$ (440) = 0.0028) and the spectral slope were higher for the Madeira River at the rising water stage of the flood (−0.0075 ± 0.0007 nm⁻¹). Kobayashi et al. [11] reported $n^{'} (λ)$ values ( $n^{'}$ (440) = 0.0034) and a spectral slope (0.007 nm⁻¹) in the Gulf of Thailand close to our results, in particular for the Madeira River during rising water. Stramski et al. [82] reported $n^{'} (λ)$ for various minerals assessing a large variability from 0.002 to 0.023 at 440 nm. Studying Lake Erie, Peng & Effler [79] assessed a significant variability on 14 samples (0.0012 – 0.0055 at 400 nm). Our results showed that $n^{'} (λ)$ displays a seasonal variability during the hydrological cycle on the Madeira River but in a much more limited range (0.0026 – 0.0038 at 400 nm) than the work presented by Stramski et al. [82], or Peng & Effler [79] for other environments / mineralogical assemblages although our samples points represent locations separated by more than 2000 km. As registered for the real part of the refraction index, this is consistent with the hydrology of large river catchments that integrate a large variety of sedimentary sources converging to an average mineralogical composition in the suspended sediment that does not vary much across the hydrological cycle. Our results show that $n^{'}$ (700) varies between 4.7 x 10⁻⁴ and 7.1 x 10⁻⁴, which is slightly lower than the values of 2.2 x 10⁻³ reported by Stramski et al. (2007) and of 1.3 x 10⁻³ reported by Dubovik et al. [83] on desert dust samples. At 850 nm, $n^{'}$ varies from 1.6 10⁻⁴ to 3.7 10⁻⁴, showing a relative percent change much stronger in relation to the values retrieved in the visible part of the spectrum. Based on these results, we considered two different $n^{'} (λ)$ values in the numerical simulations of the IOPs and AOPs for the Madeira River for the rising stage and for the other periods.

To assess the variability in the IOP during the Madeira River hydrological cycle, we computed the mass-specific absorption, the scattering and the backscattering coefficients ( $a_{N A P}^{*}$ , $b_{N A P}^{*}$ and $b_{b N A P}^{*}$ ) for each month of the year. The average monthly SSC values at the Porto Velho station from 12 years of MODIS data (2000 – 2013), as calculated by Villar et al. [32], were considered in the simulations. For the period from March to October, the refraction indices (both the real and imaginary parts) and the PSD were determined from the flood peak measurements (n = 1.173, $n^{'} (λ)$ = 0.015λ^-0.004, $J_{1}$ = 2.25, $J_{2}$ = 4.23). For the period between November and January, the refraction index and the grain size distribution were determined from the rising stage measurements (n = 1.175, $n^{'} (λ)$ = 0.063λ^-0.007, $J_{1}$ = 2.65, $J_{2}$ = 4.72). Finally, for the transition regime in February, the refraction index and the grain size distribution were calculated as averaged values between both the high water and the rising stages.

The scattering and backscattering coefficients exhibited less contrasted spectral dependence than $a_{N A P}$ [Fig. 8], and $b_{N A P}$ and $b_{b N A P}$ showed strong linear variations with the SSCs, with their values slightly increasing with increasing wavelengths. The variability of $a_{N A P}$ on a monthly scale was different: from November to February, the $a_{N A P}$ values were much lower than during the period from March to October at equivalent SSCs, thus introducing a hysteresis effect in the $a_{N A P}$ – SSC monthly variation. This hysteresis was extremely low at 440 nm and low at 550 nm, and the effect increased with the wavelengths and was the highest at 850 nm [Fig. 8]. As expected, the $a_{N A P}$ values decreased with an increase in λ (e.g., from 27.43 m⁻¹ at 440 nm to 0.99 m⁻¹ at 850 nm in January) and differed from the behavior of $b_{N A P}$ and $b_{b N A P}$ , which varied little with wavelength. Both the $a_{N A P}$ and $b_{b N A P}$ values showed relatively low values at all wavelengths in comparison to $b_{N A P}$ , (e.g., with mean values of 1.18 ± 0.82 m⁻¹, 2.85 ± 1.82 m⁻¹, and 115.90 ± 74.60 m⁻¹ at 850 nm, respectively).

Fig. 8 Monthly variations of $a_{N A P}$ , $b_{N A P}$ , $b_{b N A P}$ at 5 wavelengths on the Madeira River. Annotations represent months from January (1) to December (12).

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3.4.1 Seasonal variations in the AOP

The monthly values of $K_{d}$ and $R_{r s}$ in the Madeira River were calculated using the simulated IOPs and Eq. (14) and Eq. (15). Figure 9 shows the monthly variations of $R_{r s}$ (850), $K_{d}$ (670) and $R_{r s}$ (850)/ $R_{r s}$ (670). The simulated $R_{r s}$ (850) shows a seasonal dependence with a higher reflectance during the rising water stage than for the rest of the year [Fig. 9(a)]. The simulated $K_{d}$ (670) varied almost linearly with the SSC, although slightly lower $K_{d}$ values were found during the rising water stage than for the rest of the year at equivalent SSC values [Fig. 9(b)]. The use of the ratio $R_{r s}$ (850)/ $R_{r s}$ (670) tended to reduce the dispersion in the reflectance – SSC relationship, and showed a near linear trend compared to a one-band relationship [Fig. 9(c) and Fig. 6]. The simulations thus made it possible to reproduce the different behaviors observed for $R_{r s}$ , $K_{d}$ and $a_{N A P}$ , and IOPs simulations, which implied a seasonal dependence of $R_{r s}$ .

Fig. 9 Variations between monthly means of the AOPs and the SSCs: a) $R_{r s}$ (850); b) $K_{d}$ (670); c) reflectances band ratio between 850 and 670 nm.

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R and $R_{r s}$ [Eq. (13) and Eq. (15)] are controlled by $a_{T O T}$ and $b_{b T O T}$ and depend on $a_{N A P}$ , whose value is more sensitive to seasonal variations with increasing wavelength [Fig. 8]. During the early rising water stage (from November to February), lower $a_{N A P}$ values [Fig. 8] caused a higher reflectance than during the rest of the year. Unlike for reflectance, the model predicted a very limited seasonal effect on $K_{d}$ , as this AOP is controlled by $b_{N A P}$ [Eq. (13)], which varied linearly with the SSCs throughout the year [Fig. 8], causing a monotonic increase of $K_{d}$ values with an increasing SSC.

$b_{b N A P}$ showed very small spectral differences from 670 nm to 850 nm [Fig. 8]. In contrast, $a_{N A P}$ (670) had much higher values than $a_{N A P}$ (850), especially during the rising water stage. The former was responsible for a partial correction in the seasonal disparity in the reflectance – SSC relationship when using the band ratio $R_{r s}$ (850)/ $R_{r s}$ (670) [Fig. 9], thus showing a more linear trend in the relationship than if a single band such as $R_{r s}$ (850) was considered. Comparing these simulations to the seasonal hysteresis determined by remote sensing revealed an agreement between the physically based simulations and the satellite estimations [Fig. 10]. Despite a general underestimation of the observed $R_{r s}$ (23% on average), bio-optical modeling allowed us to reproduce the seasonal variation of $R_{r s}$ (850), especially for the rising water and the high water stages. The lack of $a_{N A P}$ measurements and $n^{'} (λ)$ determinations during the low water stage (from July to October) may explain the higher deviation observed between simulations and remote sensing estimates for this period. Furthermore, the ratio $f^{'} / Q$ used to calculate $R_{r s}$ (850) may vary spectrally around the value of 0.13, increasing jointly with the ratio $b_{b T O T}$ /( $a_{T O T} + b_{b T O T}$ [84].

Fig. 10 Comparison between the average monthly $R_{r s}$ (850) retrieved from the MODIS data [32] and the simulations from the MMP integrating in situ measurements as inputs.

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4. Discussion

4.1 PSDs

In situ measurements of particle size characteristics of fluvial suspended sediment, unlike bed sediments, are scarce for many environments upstream the estuarine zone [85]. Existing information on suspended sediment shows significant variability in the grain size distribution at the global scale [86], but some common features can be identified. Most large rivers (Amazon, Nile, Mississippi, Brahmaputra, Parana etc.) have been shown to display reduced grain size range in the bed load and suspended sediment mainly because they flow across vast plains for a major part of their course with very low topographic gradient (lower than 10 cm km⁻¹, on average) causing strong sedimentation in the foothills and floodplains [87]. Furthermore, sediment transport dynamics in a turbulent flow system implies a relatively constant distribution of the fine-grain size fraction in the water column in which the coarse-grain size fraction increases from the surface to the river bottom [88], resulting in an almost pure fine sediment composition at the river surface. In oceanic waters, the slope of the PSD are mostly centered on 4 with a suspension mostly composed by fine planktonic cells [89]. In coastal waters, lower slope values are registered, down to 3.4, owing to the presence of particles of terrestrial origin and larger planktonic species [30,90], or even less around coral reefs [46]. In continental waters dominated by non-living particles such as in river waters, $J$ values are centered towards lower values. Peng et al. [91] reported values of $J$ ranging from 2.5 to 3.2 for different lakes and rivers presenting a suspension dominated by inorganic particles in New York State. Boller & Kaegi [92] reported values up to 2.7 for some alpine waters, while Buffle & Leppard [93] showed that colloidal submicron fraction in rivers usually present a $J$ value of about 3. In our data set, values of $J$ varied between 2.7 and 3.3, when considering a single power law function over the whole grain size range, confirming the fact that inland inorganic suspensions present lower Junge exponent than in oceanic waters. As observed by Peng et al. [91] and Reynolds et al. [90], the use of a single Junge function fitting PSD over the whole grain size range may be inappropriate, especially for sediment-laden waters, as it may result in an overestimation of the smaller and larger particles. In this article, we proposed to use two Junge distributions for fine and coarse fraction, allowing to reduce the overestimation problems pointed out by Peng et al. [91]. Our slope estimates for Amazonian river waters vary within a rather narrow range for the fine size fraction [1.8-2.4] as well as for the largest fraction [3.5-4.0].

4.2 Hysteresis of the $R_{r s}$ – SSC relationship

The seasonal dependence in the $R_{r s}$ (850) – SSC relationship first described by Villar et al. [32] was deeply investigated using optical modeling and field measurements [Fig. 5]. We showed that $R_{r s}$ hysteresis was mainly driven by changes in the specific absorption from red to near-infrared which in turn was caused by variations in $n^{'}$ . Our interpretation is that PSD seasonal variability are responsible for the imaginary part of the refraction index variation. The mineralogy of particles from the Madeira River indicated a greater amount of smectite and a lower percentage of kaolinite during the early rising water period, which extends from November to February. These significant seasonal changes in the clays composition did not result in a large variation in the real part n of the refraction index because clays have a limited n range [94,95]. Furthermore, the organic particulate fraction remained very low in these sediment-laden waters, from 0.5 to 4% [51], leading to a negligible contribution of organic matter to the resulting n. The particle size distributions was segmented in two parts as proposed by Martinez et al. [50] to better fit the observed distribution. The measured PSDs indicated that particles smaller than 10 µm were more abundant during the rising water stage in the Madeira River. Such a variation of the PSD is consistent with Chipera & Bish [96], who showed that the finest fraction in a mixture of clays was mostly pure smectite. Combined variations of PSD towards finer range and clay composition in the Madeira River seemed to have affected more significantly the imaginary part of the refraction index than the real part. However, it remains important to assess which parameter (n, $n^{'}$ , PSD) is the determinant that drives the reflectance in the Amazon River basin and how is this relevant for large rivers around the world.

4.3 On the relative importance of n and PSD over the IOPs

In this section, we used a parameterization of the PSD and mineralogy representative to large river waters to analyze the sensitivity of reflectance to changes in the suspended sediment characteristics. Red and NIR wavelengths have been shown to be strongly correlated with SSC in inland and coastal waters although reflectance in the red spectrum may saturate with increasing SSC [13,50]. We focus on 670 and 850 nm wavelengths as most current spaceborne sensors suited for the study of inland waters (LANDSAT 8, SENTINEL-2) offer spectral bands at those wavelengths. We paid special attention to the sensitivity of the resulting spectral ratio that several studies have indicated as an efficient method to limit the reflectance sensitivity to the suspended sediment characteristics [21,50,97]. We also evaluated the contributions of the particle size classes on the IOPs values by following the modeling protocol described in Stramski & Kiefer [69] for different PSDs, and by including absorption processes using $n^{'} (λ)$ values retrieved from Kobayashi et al. [11].

Figure 11 shows the relative contributions of 10 suspended sediment size classes [0-100 µm] for two refraction index values and two PSDs to absorption, scattering and backscattering. As expected, smaller particles have a higher contribution to the IOPs with increasing values of $J$ (i.e., with more fine material). Small particles (D < 8 µm) were responsible for the majority of the scattering and backscattering processes from 60% to 63% with $J$ = 3 and from 67% to 78% with $J$ = 3.5 for $b_{N A P}$ , and from 83% to 86% with $J$ = 3 and from 86% to 92% with $J$ = 3.5 for $b_{b N A P}$ . These estimates are consistent with the results by Peng et al. [91] who assessed that 50% of the total scattering and backscattering processes where resulting from particles with diameter less than 5 µm in suspension from inland waters dominated by inorganic matter. Variations in the n values between 1.15 and 1.20 had a very small effect on the absorption coefficient but strongly impacted the scattering and backscattering coefficients: an increasing n value increased the importance of the smallest fraction in the particles population on the scattering and backscattering effect. These results are of special significance for large rivers where fine particles are predicted to dominate the inorganic suspension at the river surface as coarser suspension sediments increase in concentration toward the bottom of the water column. Walling and Moorehead [86] compared particle size distribution in the water column, in terms of mass, for several rivers across the world showing that suspended sediment smaller than 20 µm represent 50 to 100% of the total mass in all cases. More recent results acquired either on the Amazon River [98], the Parana River [99] or on temperate rivers [100] confirm the fact that water samples acquired at river surface usually display a unique size mode centered on fine sizes (e.g., < 20 µm). Suspended sediment loads of rivers can be transported in composite particles but it is far from straightforward to quantify the relative importance of discrete and composite particles in river suspended sediment loads [85]. The importance of fine particles on the scattering and backscattering processes suggests that knowledges of their size distribution need to be improved, and particularly in composites particles, to better characterize the optical properties of inland waters.

Fig. 11 Contributions of 10 different particle size classes (in µm) to the absorption, scattering and backscattering processes (from the top line to the bottom, respectively) for two refraction indices n and two PSDs. The size classes were extracted from Stramski & Kiefer [69].

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4.4 On the relative importance of $n$ , $n^{'}$ and PSD over the AOPs

We analyzed the theoretical sensitivity of $R_{r s}$ to PSD and mineralogy using modeling. For PSD, we stepped the $J_{1}$ values between 1.5 and 3.0 by increments of 0.5 while setting $J_{2}$ to 4. For mineralogy, the $n^{'} (λ)$ values were stepped between 0 and 0.001 by increments of 0.0005 and n varied from 1.165 to 1.185 [Fig. 12]. Each of these new simulations corresponded to a single combination of these parameters at 670 nm and 850 nm. $R_{r s}$ (850) showed moderated sensitivity to $n^{'}$ , with a relative variation of 20% when $n^{'}$ varies from 0 to 10⁻³. $R_{r s}$ (850) showed also moderated sensitivity to n, with a relative variation of 25% when varies from 1.165 to 1.185. $R_{r s}$ (670) showed much stronger sensitivity to $n^{'}$ with a relative variation of 50% when $n^{'}$ varies from 0 to 10⁻³. On the contrary, $R_{r s}$ (670) showed little variability as a function of n with a relative variation of 5%. At both wavelengths, $R_{r s}$ showed low to moderate sensitivity (7 to 17%) to the PSD (when $J_{1}$ varied from 1.5 to 3) with a relative variation increasing with increasing $n^{'}$ and n. Therefore, it appears on Fig. 12 that $n^{'}$ variations play a major role in $R_{r s}$ sensitivity to suspended sediment characteristics and that this variability is stronger at red wavelength where $a_{A N P}$ is stronger. However, $n^{'}$ is itself a function of suspended sediment mineralogy and grain size distribution in a complex way. We further analyzed the role of PSD and mineralogy by setting $n^{'}$ to a constant value.

Fig. 12 Evolution of $R_{r s}$ (850) and $R_{r s}$ (670) as a function of the imaginary part $n^{'}$ of the refraction index for different $J_{2}$ values (c.f. legend of each graphic) and two $n$ values.

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Figure 13 shows the variation in $R_{r s}$ (850), $R_{r s}$ (670) and $R_{r s}$ (850)/ $R_{r s}$ (670) as a function of $J_{1}$ and n, with n values typical of most clay particles. For PSD, we tested increasing $J_{1}$ values with the $J_{2}$ value set to 4. For distribution towards coarser particles (i.e., with lower slopes), the reflectance varied smoothly as a function of PSD. When $J_{1}$ varied from 2 to 3, reflectance varied by 18% at infra-red wavelength [Fig. 13(a)] and by 24% in the red [Fig. 13(b)]. For the same size distribution variation, the $R_{r s}$ (850)/ $R_{r s}$ (670) ratio varied by only 5% [Fig. 13(c)]. For finer distributions (i.e., those with higher slopes), the reflectance varied rapidly as a function of $J_{1}$ . As $J_{1}$ varied from 3.75 to 4.5, the reflectance varied by 70% in the infra-red [Fig. 13(a)] and by 55% in the red [Fig. 13(b)]. For the same size distribution variation, the $R_{r s}$ (850)/ $R_{r s}$ (670) ratio varied by 33% [Fig. 13(c)]. The reflectance showed maximum value for $J_{1}$ varying from 3.5 to 3.75 probably under the influence of backscattering processes that has been shown to increase from $J$ = 3 to 4 [30] and then to decrease from 4 to 5 (considering a unique slope $J$ parameter). The impact of the mineralogical variations changed according to the particle size distribution and wavelength. $R_{r s}$ (850) variations as a function of mineralogical variations were rather stable, from 24 to 28% when n varied from 1.165 to 1.185, and for any value of $J_{1}$ . For a high value of $J_{1}$ , n appeared to have moderated effect on reflectance at red wavelength (e.g., when n varied from 1.165 to 1.185 and for $J_{1}$ = 4.25, $R_{r s}$ (670) varied by 17%). In contrast, for low values of $J_{1}$ , $R_{r s}$ (670) variations were small as a function of the n values (e.g., for $J_{1}$ = 2.5, when n varied from 1.165 to 1.185, $R_{r s}$ (670) varied by 9%). Accordingly, $R_{r s}$ (850)/ $R_{r s}$ (670) showed limited sensitivity to mineralogical variations from 8 to 18% when n varied from 1.165 to 1.185.

Fig. 13 Variations in the simulated a) $R_{r s}$ (850), b) $R_{r s}$ (670) and c) $R_{r s}$ (850)/ $R_{r s}$ (670) for various PSDs (through the slope $J_{2}$ of the PSD for their finer particles) and for different values of $n$ (the real part of the sediment refraction index).

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These simulations confirmed that the use of the band ratio makes the reduction of the reflectance sensitivity to suspended sediment characteristics possible in most cases. The impact of the variability in the particle size distribution and the mineralogy on reflectance showed a rather complex pattern with a significant sensitivity of the reflectance ratio on mineralogy for a coarser distribution. When $J_{1}$ varied from 1.5 to 3, the reflectance ratio was almost unaffected by PSD variations (e.g., relative variation lower than 5%) showing much greater stability in relation to reflectance. For the same size distribution variation, $R_{r s}$ (850) and $R_{r s}$ (670) varied by 22% and 29%, respectively. In contrast, mineralogy has little effect on the reflectance ratio for distributions of finer size. For the PSD corresponding to sediment-laden waters in large river basins ( $J_{1}$ < 3), $R_{r s}$ (850) and reflectance ratio vary weakly. However, for $J_{1}$ < 3.5, $R_{r s}$ at red and infrared appears to be significantly sensitive to changes in sediment mineralogy, either through n or $n^{'}$ . It is expected that for a river catchment showing rather stable sediment sources during the hydrological cycle, the $R_{r s}$ – SSC relationship may be robust as PSD variations induce limited impact on $R_{r s}$ (850) and $R_{r s}$ (850)/ $R_{r s}$ (670). On the contrary, $R_{r s}$ (670) shows stronger sensitivity to PSD and may experience significant changes as a function of PSD and thus local hydraulic conditions from foothills to the estuary.

5. Conclusion

We investigated the AOPs and the IOPs of the river waters of the Amazon basin catchment using field measurements and modeling. The field campaigns provided a large data set of radiometric, physico-chemical, sedimentological (PSD and mineralogy) parameters for the two main tributaries of the Amazon catchment (the Solimões and Madeira Rivers) with respect to sediment discharge. This experimental database allowed us to improve our knowledge of the relationships between the inherent or apparent optical properties and the suspended sediment concentrations. The optical properties of the Madeira River were shown to be significantly different from the rest of the catchment. Indeed, its geographical origin, drainage area, and hydrological cycle confer a seasonal behavior different from that of the Solimões River on this large tributary.

The presence of a seasonal hysteresis in the $R_{r s}$ (850) – SSC relationship for the Madeira River was caused by seasonal changes in the mineralogy and PSD, showing that variability of the AOPs and IOPS in response to changes in the suspended load characteristics during the hydrological cycle may limit the accuracy of the SSC retrieval based on remote sensing data.

Our results showed that the imaginary part of the refraction index was the main origin of the hysteresis in the $R_{r s}$ (850) – SSC relationship of the sediment-laden Madeira River via a strong effect on the absorption by the suspended particles in the infra-red wavelengths. The spectral slope of $n^{'} (λ)$ from the blue region of the visible spectrum to the infra-red region decisively drove the different absorption levels during the annual hydrological cycle. The dispersion of the $R_{r s}$ (850) – SSC relationship could be overcome to some extent using of a ratio between the infra-red and the red spectral bands $R_{r s}$ (850)/ $R_{r s}$ (670). Temporal changes in the mineralogy had less effects on the scattering and backscattering coefficients for increasing wavelengths. Those properties were very sensitive to changes in the PSD and particularly to the number of particles with diameter of less than 10 µm. Backscattering was extremely dependent on the percentage of small particle size classes. This high sensitivity caused maximum reflectance values for average PSD and minimum reflectance values for sediment mixtures dominated by fine or large particles. Finally, the real part of the refraction index played a slight role in the development of the hysteresis, which was the lowest for the PSD dominated by fine particles. However, through an accentuation of the previously cited relationships between the optical properties and the characteristics of the optically active components, the role of the real part of the refraction index remained non-negligible. Therefore, particular attention must be paid to the characterization of these properties in continental waters to retrieve the SSC from water color measurements.

Finally, extending the data set to other large river basins and applying the combined use of measured, simulated and remotely sensed data seems to be a way to overcome uncertainties and to provide concrete solutions for water management agencies, especially for large basins with sediment-laden waters.

Funding

Institut de Recherche pour le Développement (IRD, France); Agência Nacional de Águas (ANA, Brésil); Centre National d’Etudes Spatiales (CNES, France); Noveltis (France). This work has been supported by the French Institut de Recherche pour le Développement (IRD) as a major partner of the Service National d’Observations HYBAM since 2003, the Brazilian Agência Nacional de Águas (ANA) for funding the sampling trips, and the French Centre National d’Etudes Spatiales (CNES) and Noveltis that cofinanced the first author PhD thesis.

Acknowledgments

The authors thank Elisa Armijos, Pascal Fraizy, Thierry Aigouy and Sophie Gouy for the technical support. The authors are also grateful to the Universidade Federal Fluminense (UFF), the Geological Survey of Brazil (CPRM) for their help during measurements. We notably thank Lucile Duforêt-Gaurier and William Moutier of the French Laboratoire d’Océanologie et de Géosciences for their support in the modeling processes, and Frédéric Julien of the French laboratoire d’Ecologie Fonctionnelle et Environnement Ecolab for his help with the absorption meter calibration.

References and links

1. P. A. Allen, “From landscapes into geological history,” Nature 451(7176), 274–276 (2008). [CrossRef] [PubMed]

2. A. J. Horowitz, “Determining annual suspended sediment and sediment-associated trace element and nutrient fluxes,” Sci. Total Environ. 400(1-3), 315–343 (2008). [CrossRef] [PubMed]

3. J. P. M. Syvitski, C. J. Vörösmarty, A. J. Kettner, and P. Green, “Impact of Humans on the Flux of Terrestrial Sediment to the Global Coastal Ocean,” Science 308(5720), 376–380 (2005). [CrossRef] [PubMed]

4. J. D. Milliman and R. H. Meade, “World-wide delivery of river sediment to the oceans,” J. Geol. 91(1), 1–21 (1983). [CrossRef]

5. S. R. Gislason, E. H. Oelkers, and Á. Snorrason, “Role of river-suspended material in the global carbon cycle,” Geology 34(1), 49–52 (2006). [CrossRef]

6. B. M. Fekete and C. J. Vörösmarty, “The current status of global river discharge monitoring and potential new technologies complementing traditional discharge measurements,” in Predictions in Ungauged Basins: PUB Kick-off (Proceedings of the PUB Kick-off Meeting Held in Brasilia, 20–22 November 2002). IAHS Publication (2002), Vol. 349.

7. J. C. Ritchie and C. M. Cooper, “Comparison of measured suspended sediment concentrations with suspended sediment concentrations estimated from Landsat MSS data,” Int. J. Remote Sens. 9(3), 379–387 (1988). [CrossRef]

8. P. Forget and S. Ouillon, “Surface suspended matter off the Rhône river mouth from visible satellite imagery,” Oceanol. Acta 21(6), 739–749 (1998). [CrossRef]

9. P. Härmä, J. Vepsäläinen, T. Hannonen, T. Pyhälahti, J. Kämäri, K. Kallio, K. Eloheimo, and S. Koponen, “Detection of water quality using simulated satellite data and semi-empirical algorithms in Finland,” Sci. Total Environ. 268(1-3), 107–121 (2001). [CrossRef] [PubMed]

10. V. E. Brando and A. G. Dekker, “Satellite hyperspectral remote sensing for estimating estuarine and coastal water quality,” IEEE Trans. Geosci. Remote Sens. 41(6), 1378–1387 (2003). [CrossRef]

11. H. Kobayashi, M. Toratani, S. Matsumura, A. Siripong, T. Lirdwitayaprasit, and P. Jintasaeranee, “Optical properties of inorganic suspended solids and their influence on ocean colour remote sensing in highly turbid coastal waters,” Int. J. Remote Sens. 32(23), 8393–8420 (2011). [CrossRef]

12. L. Cai, D. Tang, and C. Li, “An investigation of spatial variation of suspended sediment concentration induced by a bay bridge based on Landsat TM and OLI data,” Adv. Space Res. 56(2), 293–303 (2015). [CrossRef]

13. S. Chen, L. Han, X. Chen, D. Li, L. Sun, and Y. Li, “Estimating wide range Total Suspended Solids concentrations from MODIS 250-m imageries: An improved method,” ISPRS J. Photogramm. Remote Sens. 99, 58–69 (2015). [CrossRef]

14. A. I. Dogliotti, K. G. Ruddick, B. Nechad, D. Doxaran, and E. Knaeps, “A single algorithm to retrieve turbidity from remotely-sensed data in all coastal and estuarine waters,” Remote Sens. Environ. 156, 157–168 (2015). [CrossRef]

15. B. Han, H. Loisel, V. Vantrepotte, X. Mériaux, P. Bryère, S. Ouillon, D. Dessailly, Q. Xing, and J. Zhu, “Development of a Semi-Analytical Algorithm for the Retrieval of Suspended Particulate Matter from Remote Sensing over Clear to Very Turbid Waters,” Remote Sens. 8(3), 211 (2016). [CrossRef]

16. J. A. Harrington Jr, F. R. Schiebe, and J. F. Nix, “Remote sensing of Lake Chicot, Arkansas: Monitoring suspended sediments, turbidity, and Secchi depth with Landsat MSS data,” Remote Sens. Environ. 39(1), 15–27 (1992). [CrossRef]

17. K. Kallio, J. Pulliainen, and P. Ylöstalo, “MERIS, MODIS and ETM+ channel configurations in the estimation of lake water quality from subsurface reflectance using semianalytical and empirical algorithms,” Geophysica 41, 31–55 (2005).

18. R. Ma, X. Ma, and J. Dai, “Hyperspectral feature analysis of chlorophyll a and suspended solids using field measurements from Taihu Lake, eastern China,” Hydrol. Sci. J. 52(4), 808–824 (2007). [CrossRef]

19. J. R. Stroud, B. M. Lesht, D. J. Schwab, D. Beletsky, and M. L. Stein, “Assimilation of satellite images into a sediment transport model of Lake Michigan,” Water Resour. Res. 45(2), W02419 (2009). [CrossRef]

20. H. Vinciková, J. Hanuš, and L. Pechar, “Spectral reflectance is a reliable water-quality estimator for small, highly turbid wetlands,” Wetlands Ecol. Manage. 23(5), 933–946 (2015). [CrossRef]

21. D. Doxaran, J.-M. Froidefond, S. Lavender, and P. Castaing, “Spectral signature of highly turbid waters: Application with SPOT data to quantify suspended particulate matter concentrations,” Remote Sens. Environ. 81(1), 149–161 (2002). [CrossRef]

22. C. Hu, Z. Chen, T. D. Clayton, P. Swarzenski, J. C. Brock, and F. E. Muller-Karger, “Assessment of estuarine water-quality indicators using MODIS medium-resolution bands: Initial results from Tampa Bay, FL,” Remote Sens. Environ. 93(3), 423–441 (2004). [CrossRef]

23. Z. Han, Y.-Q. Jin, and C.-X. Yun, “Suspended sediment concentrations in the Yangtze River estuary retrieved from the CMODIS data,” Int. J. Remote Sens. 27(19), 4329–4336 (2006). [CrossRef]

24. J. Chen, E. D’Sa, T. Cui, and X. Zhang, “A semi-analytical total suspended sediment retrieval model in turbid coastal waters: a case study in Changjiang River Estuary,” Opt. Express 21(11), 13018–13031 (2013). [CrossRef] [PubMed]

25. A. Morel and L. Prieur, “Analysis of variations in ocean color,” Limnol. Oceanogr. 22(4), 709–722 (1977). [CrossRef]

26. M. Babin, D. Stramski, G. M. Ferrari, H. Claustre, A. Bricaud, G. Obolensky, and N. Hoepffner, “Variations in the light absorption coefficients of phytoplankton, nonalgal particles, and dissolved organic matter in coastal waters around Europe,” J. Geophys. Res. 108(C7), 3211 (2003). [CrossRef]

27. D. Stramski, E. Boss, D. Bogucki, and K. J. Voss, “The role of seawater constituents in light backscattering in the ocean,” Prog. Oceanogr. 61(1), 27–56 (2004). [CrossRef]

28. E. Boss, W. S. Pegau, M. Lee, M. Twardowski, E. Shybanov, G. Korotaev, and F. Baratange, “Particulate backscattering ratio at LEO 15 and its use to study particle composition and distribution,” J. Geophys. Res. 109(C1), C01014 (2004). [CrossRef]

29. H. Loisel, X. Mériaux, J.-F. Berthon, and A. Poteau, “Investigation of the optical backscattering to scattering ratio of marine particles in relation to their biogeochemical composition in the eastern English Channel and southern North Sea,” Limnol. Oceanogr. 52(2), 739–752 (2007). [CrossRef]

30. D. Doxaran, K. Ruddick, D. McKee, B. Gentili, D. Tailliez, M. Chami, and M. Babin, “Spectral variations of light scattering by marine particles in coastal waters, from visible to near infrared,” Limnol. Oceanogr. 54(4), 1257–1271 (2009). [CrossRef]

31. S. Budhiman, M. Suhyb Salama, Z. Vekerdy, and W. Verhoef, “Deriving optical properties of Mahakam Delta coastal waters, Indonesia using in situ measurements and ocean color model inversion,” ISPRS J. Photogramm. Remote Sens. 68, 157–169 (2012). [CrossRef]

32. R. E. Villar, J.-M. Martinez, M. Le Texier, J.-L. Guyot, P. Fraizy, P. R. Meneses, and E. de Oliveira, “A study of sediment transport in the Madeira River, Brazil, using MODIS remote-sensing images,” J. S. Am. Earth Sci. 44, 45–54 (2013). [CrossRef]

33. M. Goulding, R. Barthem, and E. Ferreira, “The Smithsonian atlas of the Amazon,” Smithsonian Books, Washington and London, USA and UK. (2003).

34. J. Callède, G. Cochonneau, F. V. Alves, J.-L. Guyot, V. S. Guimarães, and E. De Oliveira, “Les apports en eau de l’Amazone à l’Océan Atlantique,” Revue des sciences de l’eau 23(3), 247 (2010). [CrossRef]

35. J. M. Martinez, J. L. Guyot, N. Filizola, and F. Sondag, “Increase in suspended sediment discharge of the Amazon River assessed by monitoring network and satellite data,” Catena 79(3), 257–264 (2009). [CrossRef]

36. J. E. Richey, C. Nobre, and C. Deser, “Amazon River discharge and climate variability: 1903 to 1985,” Science 246(4926), 101–103 (1989). [CrossRef] [PubMed]

37. J. A. Marengo, “Variations and change in South American streamflow,” Clim. Change 31(1), 99–117 (1995). [CrossRef]

38. J. Callède, J. L. Guyot, J. Ronchail, Y. L’Hôte, H. Niel, and E. de Oliveira, “Evolution du débit de l’Amazone à Óbidos de 1903 à 1999/Evolution of the River Amazon’s discharge at Óbidos from 1903 to 1999,” Hydrol. Sci. J. 49(1), 85–97 (2004). [CrossRef]

39. J. C. Espinoza Villar, J. Ronchail, J. L. Guyot, G. Cochonneau, N. Filizola, W. Lavado, E. De Oliveira, R. Pombosa, and P. Vauchel, “Spatio-temporal rainfall variability in the Amazon basin countries (Brazil, Peru, Bolivia, Colombia, and Ecuador),” Int. J. Climatol. 29(11), 1574–1594 (2009). [CrossRef]

40. N. Filizola and J. L. Guyot, “Suspended sediment yields in the Amazon basin: an assessment using the Brazilian national data set,” Hydrol. Processes 23(22), 3207–3215 (2009). [CrossRef]

41. M. Molinier, J. L. Guyot, J. Callède, E. De Oliveira, V. S. Guimarães, K. J. Cudo, and M. C. De Aquino, “Hidrologia de la cuenca amazonica Brasileira: HIBAM primeros resultados sobre la cuenca del rio Madeira - términos del balance hídrico. Metodologia,” 155–164 (1993).

42. J. L. Guyot, J. M. Jouanneau, L. Soares, G. R. Boaventura, N. Maillet, and C. Lagane, “Clay mineral composition of river sediments in the Amazon Basin,” Catena 71(2), 340–356 (2007). [CrossRef]

43. H. Bader, “The hyperbolic distribution of particle sizes,” J. Geophys. Res. 75(15), 2822–2830 (1970). [CrossRef]

44. C. E. Junge, “Air chemistry and radioactivity,” 1963 382 (1963).

45. S. B. Woźniak and D. Stramski, “Modeling the optical properties of mineral particles suspended in seawater and their influence on ocean reflectance and chlorophyll estimation from remote sensing algorithms,” Appl. Opt. 43(17), 3489–3503 (2004). [CrossRef] [PubMed]

46. A. Jouon, S. Ouillon, P. Douillet, J. P. Lefebvre, J. M. Fernandez, X. Mari, and J.-M. Froidefond, “Spatio-temporal variability in suspended particulate matter concentration and the role of aggregation on size distribution in a coral reef lagoon,” Mar. Geol. 256(1-4), 36–48 (2008). [CrossRef]

47. J. E. Harris, “Characterization of suspended matter in the Gulf of Mexico—II Particle size analysis of suspended matter from deep water,” Deep-Sea Res. 24(11), 1055–1061 (1977). [CrossRef]

48. A. Morel and Y.-H. Ahn, “Optics of heterotrophic nanoflagellates and ciliates: A tentative assessment of their scattering role in oceanic waters compared to those of bacterial and algal cells,” J. Mar. Res. 49(1), 177–202 (1991). [CrossRef]

49. C. D. Mobley, Light and Water: Radiative Transfer in Natural Waters (Academic press, 1994).

50. J.-M. Martinez, R. Espinoza-Villar, E. Armijos, and L. Silva Moreira, “The optical properties of river and floodplain waters in the Amazon River Basin: Implications for satellite-based measurements of suspended particulate matter,” J. Geophys. Res.: Earth Surface 120, 1274–1287 (2015).

51. P. Moreira-Turcq, P. Seyler, J. L. Guyot, and H. Etcheber, “Exportation of organic carbon from the Amazon River and its main tributaries,” Hydrol. Processes 17(7), 1329–1344 (2003). [CrossRef]

52. P. Forget, S. Ouillon, F. Lahet, and P. Broche, “Inversion of reflectance spectra of nonchlorophyllous turbid coastal waters,” Remote Sens. Environ. 68(3), 264–272 (1999). [CrossRef]

53. J.-P. Eberhart, Analyse Structurale et Chimique Des Matériaux (Dunod, 1989).

54. L. Kaufman and P. Rousseeuw, Clustering by Means of Medoids (North-Holland, 1987).

55. L. Breiman, “Random forests,” Mach. Learn. 45(1), 5–32 (2001). [CrossRef]

56. S. Pinet, B. Lartiges, J.-M. Martinez, and S. Ouillon, “From SEM analysis to the mineralogical composition of suspended sediments in large river basin,” in preparation.

57. C. D. Mobley, “Estimation of the remote-sensing reflectance from above-surface measurements,” Appl. Opt. 38(36), 7442–7455 (1999). [CrossRef] [PubMed]

58. J. T. Kirk, “Point-source integrating-cavity absorption meter: theoretical principles and numerical modeling,” Appl. Opt. 36(24), 6123–6128 (1997). [CrossRef] [PubMed]

59. R. A. Leathers, T. V. Downes, and C. O. Davis, “Analysis of a point-source integrating-cavity absorption meter,” Appl. Opt. 39(33), 6118–6127 (2000). [CrossRef] [PubMed]

60. R. Röttgers, W. Schönfeld, P.-R. Kipp, and R. Doerffer, “Practical test of a point-source integrating cavity absorption meter: the performance of different collector assemblies,” Appl. Opt. 44(26), 5549–5560 (2005). [CrossRef] [PubMed]

61. D. McKee, J. Piskozub, R. Röttgers, and R. A. Reynolds, “Evaluation and Improvement of an Iterative Scattering Correction Scheme for in situ Absorption and Attenuation Measurements,” J. Atmos. Ocean. Technol. 30(7), 1527–1541 (2013). [CrossRef]

62. J. Wollschläger, M. Grunwald, R. Röttgers, and W. Petersen, “Flow-through PSICAM: a new approach for determining water constituents absorption continuously,” Ocean Dyn. 63(7), 761–775 (2013). [CrossRef]

63. J. Wollschläger, R. Röttgers, W. Petersen, and K. H. Wiltshire, “Performance of absorption coefficient measurements for the in situ determination of chlorophyll-a and total suspended matter,” J. Exp. Mar. Biol. Ecol. 453, 138–147 (2014). [CrossRef]

64. R. Röttgers, D. McKee, and C. Utschig, “Temperature and salinity correction coefficients for light absorption by water in the visible to infrared spectral region,” Opt. Express 22(21), 25093–25108 (2014). [CrossRef] [PubMed]

65. F. Eyrolle, M. F. Benedetti, J. Y. Benaim, and D. Fevrier, “The distributions of colloidal and dissolved organic carbon, major elements, and trace elements in small tropical catchments,” Geochim. Cosmochim. Acta 60(19), 3643–3656 (1996). [CrossRef]

66. O. S. Pokrovsky and J. Schott, “Iron colloids/organic matter associated transport of major and trace elements in small boreal rivers and their estuaries (NW Russia),” Chem. Geol. 190(1-4), 141–179 (2002). [CrossRef]

67. W. De Rooij and C. Van der Stap, “Expansion of Mie scattering matrices in generalized spherical functions,” Astron. Astrophys. 131, 237–248 (1984).

68. H. C. Van de Hulst, Light Scattering by Small Particles (Courier Corporation, 1957).

69. D. Stramski and D. A. Kiefer, “Light scattering by microorganisms in the open ocean,” Prog. Oceanogr. 28(4), 343–383 (1991). [CrossRef]

70. N. G. Jerlov, Marine Optics (Elsevier, 1976), Vol. 14.

71. J. T. Kirk, “Volume scattering function, average cosines, and the underwater light field,” Limnol. Oceanogr. 36(3), 455–467 (1991). [CrossRef]

72. H. R. Gordon, O. B. Brown, and M. M. Jacobs, “Computed relationships between the inherent and apparent optical properties of a flat homogeneous ocean,” Appl. Opt. 14(2), 417–427 (1975). [CrossRef] [PubMed]

73. J. T. Kirk, Light and Photosynthesis in Aquatic Ecosystems (Cambridge University, 1994).

74. J.-M. Froidefond and S. Ouillon, “Introducing a mini-catamaran to perform reflectance measurements above and below the water surface,” Opt. Express 13(3), 926–936 (2005). [CrossRef] [PubMed]

75. H. Loisel and A. Morel, “Non-isotropy of the upward radiance field in typical coastal (Case 2) waters,” Int. J. Remote Sens. 22(2-3), 275–295 (2001). [CrossRef]

76. P. Kerr, “Optical mineralogy, 492 pp,” (1977).

77. E. Aas, “Refractive index of phytoplankton derived from its metabolite composition,” J. Plankton Res. 18(12), 2223–2249 (1996). [CrossRef]

78. M. Babin and D. Stramski, “Variations in the mass-specific absorption coefficient of mineral particles suspended in water,” Limnol. Oceanogr. 49(3), 756–767 (2004). [CrossRef]

79. F. Peng and S. W. Effler, “Spectral absorption properties of mineral particles in western Lake Erie: Insights from individual particle analysis,” Limnol. Oceanogr. 58(5), 1775–1789 (2013). [CrossRef]

80. C. Giardino, V. E. Brando, A. G. Dekker, N. Strömbeck, and G. Candiani, “Assessment of water quality in Lake Garda (Italy) using Hyperion,” Remote Sens. Environ. 109(2), 183–195 (2007). [CrossRef]

81. R. Ma, J. Tang, J. Dai, Y. Zhang, and Q. Song, “Absorption and scattering properties of water body in Taihu Lake, China: absorption,” Int. J. Remote Sens. 27(19), 4277–4304 (2006). [CrossRef]

82. D. Stramski, M. Babin, and S. B. Wozniak, “Variations in the optical properties of terrigenous mineral-rich particulate matter suspended in seawater,” Limnol. Oceanogr. 52(6), 2418–2433 (2007). [CrossRef]

83. O. Dubovik, B. Holben, T. F. Eck, A. Smirnov, Y. J. Kaufman, M. D. King, D. Tanré, and I. Slutsker, “Variability of absorption and optical properties of key aerosol types observed in worldwide locations,” J. Atmos. Sci. 59(3), 590–608 (2002). [CrossRef]

84. Z. Lee, S. Shang, G. Lin, J. Chen, and D. Doxaran, “On the modeling of hyperspectral remote-sensing reflectance of high-sediment-load waters in the visible to shortwave-infrared domain,” Appl. Opt. 55(7), 1738–1750 (2016). [CrossRef] [PubMed]

85. J. Woodward and D. Walling, “Composite suspended sediment particles in river systems: their incidence, dynamics and physical characteristics,” Hydrol. Processes 21(26), 3601–3614 (2007). [CrossRef]

86. D. Walling and P. Moorehead, “The particle size characteristics of fluvial suspended sediment: an overview,” in Sediment/Water Interactions (Springer, 1989), pp. 125–149.

87. E. M. Latrubesse, “Patterns of anabranching channels: The ultimate end-member adjustment of mega rivers,” Geomorphology 101(1-2), 130–145 (2008). [CrossRef]

88. H. Rouse,

89. T. S. Kostadinov, D. A. Siegel, and S. Maritorena, “Retrieval of the particle size distribution from satellite ocean color observations,” J. Geophys. Res. 114(C9), C09015 (2009). [CrossRef]

90. R. A. Reynolds, D. Stramski, V. M. Wright, and S. B. Woźniak, “Measurements and characterization of particle size distributions in coastal waters,” J. Geophys. Res. 115(C8), C08024 (2010). [CrossRef]

91. F. Peng, S. W. Effler, D. O’Donnell, M. G. Perkins, and A. Weidemann, “Role of minerogenic particles in light scattering in lakes and a river in central New York,” Appl. Opt. 46(26), 6577–6594 (2007). [CrossRef] [PubMed]

92. M. Boller and R. Kaegi, Characterization of Aquatic Particles (IWA Publishing, London, UK, 2011).

93. J. Buffle and G. G. Leppard, “Characterization of aquatic colloids and macromolecules. 1. Structure and behavior of colloidal material,” Environ. Sci. Technol. 29(9), 2169–2175 (1995). [CrossRef] [PubMed]

94. D. Lide,

95. M. S. Twardowski, E. Boss, J. B. Macdonald, W. S. Pegau, A. H. Barnard, and J. R. V. Zaneveld, “A model for estimating bulk refractive index from the optical backscattering ratio and the implications for understanding particle composition in case I and case II waters,” J. Geophys. Res. 106(C7), 14129–14142 (2001). [CrossRef]

96. S. J. Chipera and D. L. Bish, “Baseline studies of the clay minerals society source clays: powder X-ray diffraction analyses,” Clays Clay Miner. 49(5), 398–409 (2001). [CrossRef]

97. G. F. Moore, J. Aiken, and S. J. Lavender, “The atmospheric correction of water colour and the quantitative retrieval of suspended particulate matter in Case II waters: Application to MERIS,” Int. J. Remote Sens. 20(9), 1713–1733 (1999). [CrossRef]

98. J. Bouchez, J. Gaillardet, C. France-Lanord, L. Maurice, and P. Dutra-Maia, “Grain size control of river suspended sediment geochemistry: Clues from Amazon River depth profiles,” Geochem. Geophys. Geosyst. 12(3), Q03008 (2011). [CrossRef]

99. M. Guerrero, N. Rüther, R. Szupiany, S. Haun, S. Baranya, and F. Latosinski, “The Acoustic Properties of Suspended Sediment in Large Rivers: Consequences on ADCP Methods Applicability,” Water 8(1), 13 (2016). [CrossRef]

100. D. E. Walling, P. N. Owens, B. D. Waterfall, G. J. Leeks, and P. D. Wass, “The particle size characteristics of fluvial suspended sediment in the Humber and Tweed catchments, UK,” Sci. Total Environ. 251-252, 205–222 (2000). [CrossRef] [PubMed]

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References

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Year
Author
Publication

P. A. Allen, “From landscapes into geological history,” Nature 451(7176), 274–276 (2008).
[Crossref] [PubMed]
A. J. Horowitz, “Determining annual suspended sediment and sediment-associated trace element and nutrient fluxes,” Sci. Total Environ. 400(1-3), 315–343 (2008).
[Crossref] [PubMed]
J. P. M. Syvitski, C. J. Vörösmarty, A. J. Kettner, and P. Green, “Impact of Humans on the Flux of Terrestrial Sediment to the Global Coastal Ocean,” Science 308(5720), 376–380 (2005).
[Crossref] [PubMed]
J. D. Milliman and R. H. Meade, “World-wide delivery of river sediment to the oceans,” J. Geol. 91(1), 1–21 (1983).
[Crossref]
S. R. Gislason, E. H. Oelkers, and Á. Snorrason, “Role of river-suspended material in the global carbon cycle,” Geology 34(1), 49–52 (2006).
[Crossref]
B. M. Fekete and C. J. Vörösmarty, “The current status of global river discharge monitoring and potential new technologies complementing traditional discharge measurements,” in Predictions in Ungauged Basins: PUB Kick-off (Proceedings of the PUB Kick-off Meeting Held in Brasilia, 20–22 November 2002). IAHS Publication (2002), Vol. 349.
J. C. Ritchie and C. M. Cooper, “Comparison of measured suspended sediment concentrations with suspended sediment concentrations estimated from Landsat MSS data,” Int. J. Remote Sens. 9(3), 379–387 (1988).
[Crossref]
P. Forget and S. Ouillon, “Surface suspended matter off the Rhône river mouth from visible satellite imagery,” Oceanol. Acta 21(6), 739–749 (1998).
[Crossref]
P. Härmä, J. Vepsäläinen, T. Hannonen, T. Pyhälahti, J. Kämäri, K. Kallio, K. Eloheimo, and S. Koponen, “Detection of water quality using simulated satellite data and semi-empirical algorithms in Finland,” Sci. Total Environ. 268(1-3), 107–121 (2001).
[Crossref] [PubMed]
V. E. Brando and A. G. Dekker, “Satellite hyperspectral remote sensing for estimating estuarine and coastal water quality,” IEEE Trans. Geosci. Remote Sens. 41(6), 1378–1387 (2003).
[Crossref]
H. Kobayashi, M. Toratani, S. Matsumura, A. Siripong, T. Lirdwitayaprasit, and P. Jintasaeranee, “Optical properties of inorganic suspended solids and their influence on ocean colour remote sensing in highly turbid coastal waters,” Int. J. Remote Sens. 32(23), 8393–8420 (2011).
[Crossref]
L. Cai, D. Tang, and C. Li, “An investigation of spatial variation of suspended sediment concentration induced by a bay bridge based on Landsat TM and OLI data,” Adv. Space Res. 56(2), 293–303 (2015).
[Crossref]
S. Chen, L. Han, X. Chen, D. Li, L. Sun, and Y. Li, “Estimating wide range Total Suspended Solids concentrations from MODIS 250-m imageries: An improved method,” ISPRS J. Photogramm. Remote Sens. 99, 58–69 (2015).
[Crossref]
A. I. Dogliotti, K. G. Ruddick, B. Nechad, D. Doxaran, and E. Knaeps, “A single algorithm to retrieve turbidity from remotely-sensed data in all coastal and estuarine waters,” Remote Sens. Environ. 156, 157–168 (2015).
[Crossref]
B. Han, H. Loisel, V. Vantrepotte, X. Mériaux, P. Bryère, S. Ouillon, D. Dessailly, Q. Xing, and J. Zhu, “Development of a Semi-Analytical Algorithm for the Retrieval of Suspended Particulate Matter from Remote Sensing over Clear to Very Turbid Waters,” Remote Sens. 8(3), 211 (2016).
[Crossref]
J. A. Harrington, F. R. Schiebe, and J. F. Nix, “Remote sensing of Lake Chicot, Arkansas: Monitoring suspended sediments, turbidity, and Secchi depth with Landsat MSS data,” Remote Sens. Environ. 39(1), 15–27 (1992).
[Crossref]
K. Kallio, J. Pulliainen, and P. Ylöstalo, “MERIS, MODIS and ETM+ channel configurations in the estimation of lake water quality from subsurface reflectance using semianalytical and empirical algorithms,” Geophysica 41, 31–55 (2005).
R. Ma, X. Ma, and J. Dai, “Hyperspectral feature analysis of chlorophyll a and suspended solids using field measurements from Taihu Lake, eastern China,” Hydrol. Sci. J. 52(4), 808–824 (2007).
[Crossref]
J. R. Stroud, B. M. Lesht, D. J. Schwab, D. Beletsky, and M. L. Stein, “Assimilation of satellite images into a sediment transport model of Lake Michigan,” Water Resour. Res. 45(2), W02419 (2009).
[Crossref]
H. Vinciková, J. Hanuš, and L. Pechar, “Spectral reflectance is a reliable water-quality estimator for small, highly turbid wetlands,” Wetlands Ecol. Manage. 23(5), 933–946 (2015).
[Crossref]
D. Doxaran, J.-M. Froidefond, S. Lavender, and P. Castaing, “Spectral signature of highly turbid waters: Application with SPOT data to quantify suspended particulate matter concentrations,” Remote Sens. Environ. 81(1), 149–161 (2002).
[Crossref]
C. Hu, Z. Chen, T. D. Clayton, P. Swarzenski, J. C. Brock, and F. E. Muller-Karger, “Assessment of estuarine water-quality indicators using MODIS medium-resolution bands: Initial results from Tampa Bay, FL,” Remote Sens. Environ. 93(3), 423–441 (2004).
[Crossref]
Z. Han, Y.-Q. Jin, and C.-X. Yun, “Suspended sediment concentrations in the Yangtze River estuary retrieved from the CMODIS data,” Int. J. Remote Sens. 27(19), 4329–4336 (2006).
[Crossref]
J. Chen, E. D’Sa, T. Cui, and X. Zhang, “A semi-analytical total suspended sediment retrieval model in turbid coastal waters: a case study in Changjiang River Estuary,” Opt. Express 21(11), 13018–13031 (2013).
[Crossref] [PubMed]
A. Morel and L. Prieur, “Analysis of variations in ocean color,” Limnol. Oceanogr. 22(4), 709–722 (1977).
[Crossref]
M. Babin, D. Stramski, G. M. Ferrari, H. Claustre, A. Bricaud, G. Obolensky, and N. Hoepffner, “Variations in the light absorption coefficients of phytoplankton, nonalgal particles, and dissolved organic matter in coastal waters around Europe,” J. Geophys. Res. 108(C7), 3211 (2003).
[Crossref]
D. Stramski, E. Boss, D. Bogucki, and K. J. Voss, “The role of seawater constituents in light backscattering in the ocean,” Prog. Oceanogr. 61(1), 27–56 (2004).
[Crossref]
E. Boss, W. S. Pegau, M. Lee, M. Twardowski, E. Shybanov, G. Korotaev, and F. Baratange, “Particulate backscattering ratio at LEO 15 and its use to study particle composition and distribution,” J. Geophys. Res. 109(C1), C01014 (2004).
[Crossref]
H. Loisel, X. Mériaux, J.-F. Berthon, and A. Poteau, “Investigation of the optical backscattering to scattering ratio of marine particles in relation to their biogeochemical composition in the eastern English Channel and southern North Sea,” Limnol. Oceanogr. 52(2), 739–752 (2007).
[Crossref]
D. Doxaran, K. Ruddick, D. McKee, B. Gentili, D. Tailliez, M. Chami, and M. Babin, “Spectral variations of light scattering by marine particles in coastal waters, from visible to near infrared,” Limnol. Oceanogr. 54(4), 1257–1271 (2009).
[Crossref]
S. Budhiman, M. Suhyb Salama, Z. Vekerdy, and W. Verhoef, “Deriving optical properties of Mahakam Delta coastal waters, Indonesia using in situ measurements and ocean color model inversion,” ISPRS J. Photogramm. Remote Sens. 68, 157–169 (2012).
[Crossref]
R. E. Villar, J.-M. Martinez, M. Le Texier, J.-L. Guyot, P. Fraizy, P. R. Meneses, and E. de Oliveira, “A study of sediment transport in the Madeira River, Brazil, using MODIS remote-sensing images,” J. S. Am. Earth Sci. 44, 45–54 (2013).
[Crossref]
M. Goulding, R. Barthem, and E. Ferreira, “The Smithsonian atlas of the Amazon,” Smithsonian Books, Washington and London, USA and UK. (2003).
J. Callède, G. Cochonneau, F. V. Alves, J.-L. Guyot, V. S. Guimarães, and E. De Oliveira, “Les apports en eau de l’Amazone à l’Océan Atlantique,” Revue des sciences de l’eau 23(3), 247 (2010).
[Crossref]
J. M. Martinez, J. L. Guyot, N. Filizola, and F. Sondag, “Increase in suspended sediment discharge of the Amazon River assessed by monitoring network and satellite data,” Catena 79(3), 257–264 (2009).
[Crossref]
J. E. Richey, C. Nobre, and C. Deser, “Amazon River discharge and climate variability: 1903 to 1985,” Science 246(4926), 101–103 (1989).
[Crossref] [PubMed]
J. A. Marengo, “Variations and change in South American streamflow,” Clim. Change 31(1), 99–117 (1995).
[Crossref]
J. Callède, J. L. Guyot, J. Ronchail, Y. L’Hôte, H. Niel, and E. de Oliveira, “Evolution du débit de l’Amazone à Óbidos de 1903 à 1999/Evolution of the River Amazon’s discharge at Óbidos from 1903 to 1999,” Hydrol. Sci. J. 49(1), 85–97 (2004).
[Crossref]
J. C. Espinoza Villar, J. Ronchail, J. L. Guyot, G. Cochonneau, N. Filizola, W. Lavado, E. De Oliveira, R. Pombosa, and P. Vauchel, “Spatio-temporal rainfall variability in the Amazon basin countries (Brazil, Peru, Bolivia, Colombia, and Ecuador),” Int. J. Climatol. 29(11), 1574–1594 (2009).
[Crossref]
N. Filizola and J. L. Guyot, “Suspended sediment yields in the Amazon basin: an assessment using the Brazilian national data set,” Hydrol. Processes 23(22), 3207–3215 (2009).
[Crossref]
M. Molinier, J. L. Guyot, J. Callède, E. De Oliveira, V. S. Guimarães, K. J. Cudo, and M. C. De Aquino, “Hidrologia de la cuenca amazonica Brasileira: HIBAM primeros resultados sobre la cuenca del rio Madeira - términos del balance hídrico. Metodologia,” 155–164 (1993).
J. L. Guyot, J. M. Jouanneau, L. Soares, G. R. Boaventura, N. Maillet, and C. Lagane, “Clay mineral composition of river sediments in the Amazon Basin,” Catena 71(2), 340–356 (2007).
[Crossref]
H. Bader, “The hyperbolic distribution of particle sizes,” J. Geophys. Res. 75(15), 2822–2830 (1970).
[Crossref]
C. E. Junge, “Air chemistry and radioactivity,” 1963 382 (1963).
S. B. Woźniak and D. Stramski, “Modeling the optical properties of mineral particles suspended in seawater and their influence on ocean reflectance and chlorophyll estimation from remote sensing algorithms,” Appl. Opt. 43(17), 3489–3503 (2004).
[Crossref] [PubMed]
A. Jouon, S. Ouillon, P. Douillet, J. P. Lefebvre, J. M. Fernandez, X. Mari, and J.-M. Froidefond, “Spatio-temporal variability in suspended particulate matter concentration and the role of aggregation on size distribution in a coral reef lagoon,” Mar. Geol. 256(1-4), 36–48 (2008).
[Crossref]
J. E. Harris, “Characterization of suspended matter in the Gulf of Mexico—II Particle size analysis of suspended matter from deep water,” Deep-Sea Res. 24(11), 1055–1061 (1977).
[Crossref]
A. Morel and Y.-H. Ahn, “Optics of heterotrophic nanoflagellates and ciliates: A tentative assessment of their scattering role in oceanic waters compared to those of bacterial and algal cells,” J. Mar. Res. 49(1), 177–202 (1991).
[Crossref]
C. D. Mobley, Light and Water: Radiative Transfer in Natural Waters (Academic press, 1994).
J.-M. Martinez, R. Espinoza-Villar, E. Armijos, and L. Silva Moreira, “The optical properties of river and floodplain waters in the Amazon River Basin: Implications for satellite-based measurements of suspended particulate matter,” J. Geophys. Res.: Earth Surface 120, 1274–1287 (2015).
P. Moreira-Turcq, P. Seyler, J. L. Guyot, and H. Etcheber, “Exportation of organic carbon from the Amazon River and its main tributaries,” Hydrol. Processes 17(7), 1329–1344 (2003).
[Crossref]
P. Forget, S. Ouillon, F. Lahet, and P. Broche, “Inversion of reflectance spectra of nonchlorophyllous turbid coastal waters,” Remote Sens. Environ. 68(3), 264–272 (1999).
[Crossref]
J.-P. Eberhart, Analyse Structurale et Chimique Des Matériaux (Dunod, 1989).
L. Kaufman and P. Rousseeuw, Clustering by Means of Medoids (North-Holland, 1987).
L. Breiman, “Random forests,” Mach. Learn. 45(1), 5–32 (2001).
[Crossref]
S. Pinet, B. Lartiges, J.-M. Martinez, and S. Ouillon, “From SEM analysis to the mineralogical composition of suspended sediments in large river basin,” in preparation.
C. D. Mobley, “Estimation of the remote-sensing reflectance from above-surface measurements,” Appl. Opt. 38(36), 7442–7455 (1999).
[Crossref] [PubMed]
J. T. Kirk, “Point-source integrating-cavity absorption meter: theoretical principles and numerical modeling,” Appl. Opt. 36(24), 6123–6128 (1997).
[Crossref] [PubMed]
R. A. Leathers, T. V. Downes, and C. O. Davis, “Analysis of a point-source integrating-cavity absorption meter,” Appl. Opt. 39(33), 6118–6127 (2000).
[Crossref] [PubMed]
R. Röttgers, W. Schönfeld, P.-R. Kipp, and R. Doerffer, “Practical test of a point-source integrating cavity absorption meter: the performance of different collector assemblies,” Appl. Opt. 44(26), 5549–5560 (2005).
[Crossref] [PubMed]
D. McKee, J. Piskozub, R. Röttgers, and R. A. Reynolds, “Evaluation and Improvement of an Iterative Scattering Correction Scheme for in situ Absorption and Attenuation Measurements,” J. Atmos. Ocean. Technol. 30(7), 1527–1541 (2013).
[Crossref]
J. Wollschläger, M. Grunwald, R. Röttgers, and W. Petersen, “Flow-through PSICAM: a new approach for determining water constituents absorption continuously,” Ocean Dyn. 63(7), 761–775 (2013).
[Crossref]
J. Wollschläger, R. Röttgers, W. Petersen, and K. H. Wiltshire, “Performance of absorption coefficient measurements for the in situ determination of chlorophyll-a and total suspended matter,” J. Exp. Mar. Biol. Ecol. 453, 138–147 (2014).
[Crossref]
R. Röttgers, D. McKee, and C. Utschig, “Temperature and salinity correction coefficients for light absorption by water in the visible to infrared spectral region,” Opt. Express 22(21), 25093–25108 (2014).
[Crossref] [PubMed]
F. Eyrolle, M. F. Benedetti, J. Y. Benaim, and D. Fevrier, “The distributions of colloidal and dissolved organic carbon, major elements, and trace elements in small tropical catchments,” Geochim. Cosmochim. Acta 60(19), 3643–3656 (1996).
[Crossref]
O. S. Pokrovsky and J. Schott, “Iron colloids/organic matter associated transport of major and trace elements in small boreal rivers and their estuaries (NW Russia),” Chem. Geol. 190(1-4), 141–179 (2002).
[Crossref]
W. De Rooij and C. Van der Stap, “Expansion of Mie scattering matrices in generalized spherical functions,” Astron. Astrophys. 131, 237–248 (1984).
H. C. Van de Hulst, Light Scattering by Small Particles (Courier Corporation, 1957).
D. Stramski and D. A. Kiefer, “Light scattering by microorganisms in the open ocean,” Prog. Oceanogr. 28(4), 343–383 (1991).
[Crossref]
N. G. Jerlov, Marine Optics (Elsevier, 1976), Vol. 14.
J. T. Kirk, “Volume scattering function, average cosines, and the underwater light field,” Limnol. Oceanogr. 36(3), 455–467 (1991).
[Crossref]
H. R. Gordon, O. B. Brown, and M. M. Jacobs, “Computed relationships between the inherent and apparent optical properties of a flat homogeneous ocean,” Appl. Opt. 14(2), 417–427 (1975).
[Crossref] [PubMed]
J. T. Kirk, Light and Photosynthesis in Aquatic Ecosystems (Cambridge University, 1994).
J.-M. Froidefond and S. Ouillon, “Introducing a mini-catamaran to perform reflectance measurements above and below the water surface,” Opt. Express 13(3), 926–936 (2005).
[Crossref] [PubMed]
H. Loisel and A. Morel, “Non-isotropy of the upward radiance field in typical coastal (Case 2) waters,” Int. J. Remote Sens. 22(2-3), 275–295 (2001).
[Crossref]
P. Kerr, “Optical mineralogy, 492 pp,” (1977).
E. Aas, “Refractive index of phytoplankton derived from its metabolite composition,” J. Plankton Res. 18(12), 2223–2249 (1996).
[Crossref]
M. Babin and D. Stramski, “Variations in the mass-specific absorption coefficient of mineral particles suspended in water,” Limnol. Oceanogr. 49(3), 756–767 (2004).
[Crossref]
F. Peng and S. W. Effler, “Spectral absorption properties of mineral particles in western Lake Erie: Insights from individual particle analysis,” Limnol. Oceanogr. 58(5), 1775–1789 (2013).
[Crossref]
C. Giardino, V. E. Brando, A. G. Dekker, N. Strömbeck, and G. Candiani, “Assessment of water quality in Lake Garda (Italy) using Hyperion,” Remote Sens. Environ. 109(2), 183–195 (2007).
[Crossref]
R. Ma, J. Tang, J. Dai, Y. Zhang, and Q. Song, “Absorption and scattering properties of water body in Taihu Lake, China: absorption,” Int. J. Remote Sens. 27(19), 4277–4304 (2006).
[Crossref]
D. Stramski, M. Babin, and S. B. Wozniak, “Variations in the optical properties of terrigenous mineral-rich particulate matter suspended in seawater,” Limnol. Oceanogr. 52(6), 2418–2433 (2007).
[Crossref]
O. Dubovik, B. Holben, T. F. Eck, A. Smirnov, Y. J. Kaufman, M. D. King, D. Tanré, and I. Slutsker, “Variability of absorption and optical properties of key aerosol types observed in worldwide locations,” J. Atmos. Sci. 59(3), 590–608 (2002).
[Crossref]
Z. Lee, S. Shang, G. Lin, J. Chen, and D. Doxaran, “On the modeling of hyperspectral remote-sensing reflectance of high-sediment-load waters in the visible to shortwave-infrared domain,” Appl. Opt. 55(7), 1738–1750 (2016).
[Crossref] [PubMed]
J. Woodward and D. Walling, “Composite suspended sediment particles in river systems: their incidence, dynamics and physical characteristics,” Hydrol. Processes 21(26), 3601–3614 (2007).
[Crossref]
D. Walling and P. Moorehead, “The particle size characteristics of fluvial suspended sediment: an overview,” in Sediment/Water Interactions (Springer, 1989), pp. 125–149.
E. M. Latrubesse, “Patterns of anabranching channels: The ultimate end-member adjustment of mega rivers,” Geomorphology 101(1-2), 130–145 (2008).
[Crossref]
H. Rouse,
T. S. Kostadinov, D. A. Siegel, and S. Maritorena, “Retrieval of the particle size distribution from satellite ocean color observations,” J. Geophys. Res. 114(C9), C09015 (2009).
[Crossref]
R. A. Reynolds, D. Stramski, V. M. Wright, and S. B. Woźniak, “Measurements and characterization of particle size distributions in coastal waters,” J. Geophys. Res. 115(C8), C08024 (2010).
[Crossref]
F. Peng, S. W. Effler, D. O’Donnell, M. G. Perkins, and A. Weidemann, “Role of minerogenic particles in light scattering in lakes and a river in central New York,” Appl. Opt. 46(26), 6577–6594 (2007).
[Crossref] [PubMed]
M. Boller and R. Kaegi, Characterization of Aquatic Particles (IWA Publishing, London, UK, 2011).
J. Buffle and G. G. Leppard, “Characterization of aquatic colloids and macromolecules. 1. Structure and behavior of colloidal material,” Environ. Sci. Technol. 29(9), 2169–2175 (1995).
[Crossref] [PubMed]
D. Lide,
M. S. Twardowski, E. Boss, J. B. Macdonald, W. S. Pegau, A. H. Barnard, and J. R. V. Zaneveld, “A model for estimating bulk refractive index from the optical backscattering ratio and the implications for understanding particle composition in case I and case II waters,” J. Geophys. Res. 106(C7), 14129–14142 (2001).
[Crossref]
S. J. Chipera and D. L. Bish, “Baseline studies of the clay minerals society source clays: powder X-ray diffraction analyses,” Clays Clay Miner. 49(5), 398–409 (2001).
[Crossref]
G. F. Moore, J. Aiken, and S. J. Lavender, “The atmospheric correction of water colour and the quantitative retrieval of suspended particulate matter in Case II waters: Application to MERIS,” Int. J. Remote Sens. 20(9), 1713–1733 (1999).
[Crossref]
J. Bouchez, J. Gaillardet, C. France-Lanord, L. Maurice, and P. Dutra-Maia, “Grain size control of river suspended sediment geochemistry: Clues from Amazon River depth profiles,” Geochem. Geophys. Geosyst. 12(3), Q03008 (2011).
[Crossref]
M. Guerrero, N. Rüther, R. Szupiany, S. Haun, S. Baranya, and F. Latosinski, “The Acoustic Properties of Suspended Sediment in Large Rivers: Consequences on ADCP Methods Applicability,” Water 8(1), 13 (2016).
[Crossref]
D. E. Walling, P. N. Owens, B. D. Waterfall, G. J. Leeks, and P. D. Wass, “The particle size characteristics of fluvial suspended sediment in the Humber and Tweed catchments, UK,” Sci. Total Environ. 251-252, 205–222 (2000).
[Crossref] [PubMed]

2016 (3)

B. Han, H. Loisel, V. Vantrepotte, X. Mériaux, P. Bryère, S. Ouillon, D. Dessailly, Q. Xing, and J. Zhu, “Development of a Semi-Analytical Algorithm for the Retrieval of Suspended Particulate Matter from Remote Sensing over Clear to Very Turbid Waters,” Remote Sens. 8(3), 211 (2016).
[Crossref]

Z. Lee, S. Shang, G. Lin, J. Chen, and D. Doxaran, “On the modeling of hyperspectral remote-sensing reflectance of high-sediment-load waters in the visible to shortwave-infrared domain,” Appl. Opt. 55(7), 1738–1750 (2016).
[Crossref] [PubMed]

M. Guerrero, N. Rüther, R. Szupiany, S. Haun, S. Baranya, and F. Latosinski, “The Acoustic Properties of Suspended Sediment in Large Rivers: Consequences on ADCP Methods Applicability,” Water 8(1), 13 (2016).
[Crossref]

2015 (5)

L. Cai, D. Tang, and C. Li, “An investigation of spatial variation of suspended sediment concentration induced by a bay bridge based on Landsat TM and OLI data,” Adv. Space Res. 56(2), 293–303 (2015).
[Crossref]

S. Chen, L. Han, X. Chen, D. Li, L. Sun, and Y. Li, “Estimating wide range Total Suspended Solids concentrations from MODIS 250-m imageries: An improved method,” ISPRS J. Photogramm. Remote Sens. 99, 58–69 (2015).
[Crossref]

A. I. Dogliotti, K. G. Ruddick, B. Nechad, D. Doxaran, and E. Knaeps, “A single algorithm to retrieve turbidity from remotely-sensed data in all coastal and estuarine waters,” Remote Sens. Environ. 156, 157–168 (2015).
[Crossref]

H. Vinciková, J. Hanuš, and L. Pechar, “Spectral reflectance is a reliable water-quality estimator for small, highly turbid wetlands,” Wetlands Ecol. Manage. 23(5), 933–946 (2015).
[Crossref]

J.-M. Martinez, R. Espinoza-Villar, E. Armijos, and L. Silva Moreira, “The optical properties of river and floodplain waters in the Amazon River Basin: Implications for satellite-based measurements of suspended particulate matter,” J. Geophys. Res.: Earth Surface 120, 1274–1287 (2015).

2014 (2)

J. Wollschläger, R. Röttgers, W. Petersen, and K. H. Wiltshire, “Performance of absorption coefficient measurements for the in situ determination of chlorophyll-a and total suspended matter,” J. Exp. Mar. Biol. Ecol. 453, 138–147 (2014).
[Crossref]

R. Röttgers, D. McKee, and C. Utschig, “Temperature and salinity correction coefficients for light absorption by water in the visible to infrared spectral region,” Opt. Express 22(21), 25093–25108 (2014).
[Crossref] [PubMed]

2013 (5)

D. McKee, J. Piskozub, R. Röttgers, and R. A. Reynolds, “Evaluation and Improvement of an Iterative Scattering Correction Scheme for in situ Absorption and Attenuation Measurements,” J. Atmos. Ocean. Technol. 30(7), 1527–1541 (2013).
[Crossref]

J. Wollschläger, M. Grunwald, R. Röttgers, and W. Petersen, “Flow-through PSICAM: a new approach for determining water constituents absorption continuously,” Ocean Dyn. 63(7), 761–775 (2013).
[Crossref]

F. Peng and S. W. Effler, “Spectral absorption properties of mineral particles in western Lake Erie: Insights from individual particle analysis,” Limnol. Oceanogr. 58(5), 1775–1789 (2013).
[Crossref]

J. Chen, E. D’Sa, T. Cui, and X. Zhang, “A semi-analytical total suspended sediment retrieval model in turbid coastal waters: a case study in Changjiang River Estuary,” Opt. Express 21(11), 13018–13031 (2013).
[Crossref] [PubMed]

R. E. Villar, J.-M. Martinez, M. Le Texier, J.-L. Guyot, P. Fraizy, P. R. Meneses, and E. de Oliveira, “A study of sediment transport in the Madeira River, Brazil, using MODIS remote-sensing images,” J. S. Am. Earth Sci. 44, 45–54 (2013).
[Crossref]

2012 (1)

S. Budhiman, M. Suhyb Salama, Z. Vekerdy, and W. Verhoef, “Deriving optical properties of Mahakam Delta coastal waters, Indonesia using in situ measurements and ocean color model inversion,” ISPRS J. Photogramm. Remote Sens. 68, 157–169 (2012).
[Crossref]

2011 (2)

H. Kobayashi, M. Toratani, S. Matsumura, A. Siripong, T. Lirdwitayaprasit, and P. Jintasaeranee, “Optical properties of inorganic suspended solids and their influence on ocean colour remote sensing in highly turbid coastal waters,” Int. J. Remote Sens. 32(23), 8393–8420 (2011).
[Crossref]

J. Bouchez, J. Gaillardet, C. France-Lanord, L. Maurice, and P. Dutra-Maia, “Grain size control of river suspended sediment geochemistry: Clues from Amazon River depth profiles,” Geochem. Geophys. Geosyst. 12(3), Q03008 (2011).
[Crossref]

2010 (2)

R. A. Reynolds, D. Stramski, V. M. Wright, and S. B. Woźniak, “Measurements and characterization of particle size distributions in coastal waters,” J. Geophys. Res. 115(C8), C08024 (2010).
[Crossref]

J. Callède, G. Cochonneau, F. V. Alves, J.-L. Guyot, V. S. Guimarães, and E. De Oliveira, “Les apports en eau de l’Amazone à l’Océan Atlantique,” Revue des sciences de l’eau 23(3), 247 (2010).
[Crossref]

2009 (6)

J. M. Martinez, J. L. Guyot, N. Filizola, and F. Sondag, “Increase in suspended sediment discharge of the Amazon River assessed by monitoring network and satellite data,” Catena 79(3), 257–264 (2009).
[Crossref]

D. Doxaran, K. Ruddick, D. McKee, B. Gentili, D. Tailliez, M. Chami, and M. Babin, “Spectral variations of light scattering by marine particles in coastal waters, from visible to near infrared,” Limnol. Oceanogr. 54(4), 1257–1271 (2009).
[Crossref]

J. R. Stroud, B. M. Lesht, D. J. Schwab, D. Beletsky, and M. L. Stein, “Assimilation of satellite images into a sediment transport model of Lake Michigan,” Water Resour. Res. 45(2), W02419 (2009).
[Crossref]

J. C. Espinoza Villar, J. Ronchail, J. L. Guyot, G. Cochonneau, N. Filizola, W. Lavado, E. De Oliveira, R. Pombosa, and P. Vauchel, “Spatio-temporal rainfall variability in the Amazon basin countries (Brazil, Peru, Bolivia, Colombia, and Ecuador),” Int. J. Climatol. 29(11), 1574–1594 (2009).
[Crossref]

N. Filizola and J. L. Guyot, “Suspended sediment yields in the Amazon basin: an assessment using the Brazilian national data set,” Hydrol. Processes 23(22), 3207–3215 (2009).
[Crossref]

T. S. Kostadinov, D. A. Siegel, and S. Maritorena, “Retrieval of the particle size distribution from satellite ocean color observations,” J. Geophys. Res. 114(C9), C09015 (2009).
[Crossref]

2008 (4)

E. M. Latrubesse, “Patterns of anabranching channels: The ultimate end-member adjustment of mega rivers,” Geomorphology 101(1-2), 130–145 (2008).
[Crossref]

A. Jouon, S. Ouillon, P. Douillet, J. P. Lefebvre, J. M. Fernandez, X. Mari, and J.-M. Froidefond, “Spatio-temporal variability in suspended particulate matter concentration and the role of aggregation on size distribution in a coral reef lagoon,” Mar. Geol. 256(1-4), 36–48 (2008).
[Crossref]

P. A. Allen, “From landscapes into geological history,” Nature 451(7176), 274–276 (2008).
[Crossref] [PubMed]

A. J. Horowitz, “Determining annual suspended sediment and sediment-associated trace element and nutrient fluxes,” Sci. Total Environ. 400(1-3), 315–343 (2008).
[Crossref] [PubMed]

2007 (7)

R. Ma, X. Ma, and J. Dai, “Hyperspectral feature analysis of chlorophyll a and suspended solids using field measurements from Taihu Lake, eastern China,” Hydrol. Sci. J. 52(4), 808–824 (2007).
[Crossref]

H. Loisel, X. Mériaux, J.-F. Berthon, and A. Poteau, “Investigation of the optical backscattering to scattering ratio of marine particles in relation to their biogeochemical composition in the eastern English Channel and southern North Sea,” Limnol. Oceanogr. 52(2), 739–752 (2007).
[Crossref]

J. L. Guyot, J. M. Jouanneau, L. Soares, G. R. Boaventura, N. Maillet, and C. Lagane, “Clay mineral composition of river sediments in the Amazon Basin,” Catena 71(2), 340–356 (2007).
[Crossref]

C. Giardino, V. E. Brando, A. G. Dekker, N. Strömbeck, and G. Candiani, “Assessment of water quality in Lake Garda (Italy) using Hyperion,” Remote Sens. Environ. 109(2), 183–195 (2007).
[Crossref]

D. Stramski, M. Babin, and S. B. Wozniak, “Variations in the optical properties of terrigenous mineral-rich particulate matter suspended in seawater,” Limnol. Oceanogr. 52(6), 2418–2433 (2007).
[Crossref]

J. Woodward and D. Walling, “Composite suspended sediment particles in river systems: their incidence, dynamics and physical characteristics,” Hydrol. Processes 21(26), 3601–3614 (2007).
[Crossref]

F. Peng, S. W. Effler, D. O’Donnell, M. G. Perkins, and A. Weidemann, “Role of minerogenic particles in light scattering in lakes and a river in central New York,” Appl. Opt. 46(26), 6577–6594 (2007).
[Crossref] [PubMed]

2006 (3)

R. Ma, J. Tang, J. Dai, Y. Zhang, and Q. Song, “Absorption and scattering properties of water body in Taihu Lake, China: absorption,” Int. J. Remote Sens. 27(19), 4277–4304 (2006).
[Crossref]

Z. Han, Y.-Q. Jin, and C.-X. Yun, “Suspended sediment concentrations in the Yangtze River estuary retrieved from the CMODIS data,” Int. J. Remote Sens. 27(19), 4329–4336 (2006).
[Crossref]

S. R. Gislason, E. H. Oelkers, and Á. Snorrason, “Role of river-suspended material in the global carbon cycle,” Geology 34(1), 49–52 (2006).
[Crossref]

2005 (4)

J. P. M. Syvitski, C. J. Vörösmarty, A. J. Kettner, and P. Green, “Impact of Humans on the Flux of Terrestrial Sediment to the Global Coastal Ocean,” Science 308(5720), 376–380 (2005).
[Crossref] [PubMed]

K. Kallio, J. Pulliainen, and P. Ylöstalo, “MERIS, MODIS and ETM+ channel configurations in the estimation of lake water quality from subsurface reflectance using semianalytical and empirical algorithms,” Geophysica 41, 31–55 (2005).

J.-M. Froidefond and S. Ouillon, “Introducing a mini-catamaran to perform reflectance measurements above and below the water surface,” Opt. Express 13(3), 926–936 (2005).
[Crossref] [PubMed]

R. Röttgers, W. Schönfeld, P.-R. Kipp, and R. Doerffer, “Practical test of a point-source integrating cavity absorption meter: the performance of different collector assemblies,” Appl. Opt. 44(26), 5549–5560 (2005).
[Crossref] [PubMed]

2004 (6)

M. Babin and D. Stramski, “Variations in the mass-specific absorption coefficient of mineral particles suspended in water,” Limnol. Oceanogr. 49(3), 756–767 (2004).
[Crossref]

J. Callède, J. L. Guyot, J. Ronchail, Y. L’Hôte, H. Niel, and E. de Oliveira, “Evolution du débit de l’Amazone à Óbidos de 1903 à 1999/Evolution of the River Amazon’s discharge at Óbidos from 1903 to 1999,” Hydrol. Sci. J. 49(1), 85–97 (2004).
[Crossref]

S. B. Woźniak and D. Stramski, “Modeling the optical properties of mineral particles suspended in seawater and their influence on ocean reflectance and chlorophyll estimation from remote sensing algorithms,” Appl. Opt. 43(17), 3489–3503 (2004).
[Crossref] [PubMed]

C. Hu, Z. Chen, T. D. Clayton, P. Swarzenski, J. C. Brock, and F. E. Muller-Karger, “Assessment of estuarine water-quality indicators using MODIS medium-resolution bands: Initial results from Tampa Bay, FL,” Remote Sens. Environ. 93(3), 423–441 (2004).
[Crossref]

D. Stramski, E. Boss, D. Bogucki, and K. J. Voss, “The role of seawater constituents in light backscattering in the ocean,” Prog. Oceanogr. 61(1), 27–56 (2004).
[Crossref]

E. Boss, W. S. Pegau, M. Lee, M. Twardowski, E. Shybanov, G. Korotaev, and F. Baratange, “Particulate backscattering ratio at LEO 15 and its use to study particle composition and distribution,” J. Geophys. Res. 109(C1), C01014 (2004).
[Crossref]

2003 (3)

M. Babin, D. Stramski, G. M. Ferrari, H. Claustre, A. Bricaud, G. Obolensky, and N. Hoepffner, “Variations in the light absorption coefficients of phytoplankton, nonalgal particles, and dissolved organic matter in coastal waters around Europe,” J. Geophys. Res. 108(C7), 3211 (2003).
[Crossref]

V. E. Brando and A. G. Dekker, “Satellite hyperspectral remote sensing for estimating estuarine and coastal water quality,” IEEE Trans. Geosci. Remote Sens. 41(6), 1378–1387 (2003).
[Crossref]

P. Moreira-Turcq, P. Seyler, J. L. Guyot, and H. Etcheber, “Exportation of organic carbon from the Amazon River and its main tributaries,” Hydrol. Processes 17(7), 1329–1344 (2003).
[Crossref]

2002 (3)

O. Dubovik, B. Holben, T. F. Eck, A. Smirnov, Y. J. Kaufman, M. D. King, D. Tanré, and I. Slutsker, “Variability of absorption and optical properties of key aerosol types observed in worldwide locations,” J. Atmos. Sci. 59(3), 590–608 (2002).
[Crossref]

O. S. Pokrovsky and J. Schott, “Iron colloids/organic matter associated transport of major and trace elements in small boreal rivers and their estuaries (NW Russia),” Chem. Geol. 190(1-4), 141–179 (2002).
[Crossref]

D. Doxaran, J.-M. Froidefond, S. Lavender, and P. Castaing, “Spectral signature of highly turbid waters: Application with SPOT data to quantify suspended particulate matter concentrations,” Remote Sens. Environ. 81(1), 149–161 (2002).
[Crossref]

2001 (5)

P. Härmä, J. Vepsäläinen, T. Hannonen, T. Pyhälahti, J. Kämäri, K. Kallio, K. Eloheimo, and S. Koponen, “Detection of water quality using simulated satellite data and semi-empirical algorithms in Finland,” Sci. Total Environ. 268(1-3), 107–121 (2001).
[Crossref] [PubMed]

H. Loisel and A. Morel, “Non-isotropy of the upward radiance field in typical coastal (Case 2) waters,” Int. J. Remote Sens. 22(2-3), 275–295 (2001).
[Crossref]

L. Breiman, “Random forests,” Mach. Learn. 45(1), 5–32 (2001).
[Crossref]

M. S. Twardowski, E. Boss, J. B. Macdonald, W. S. Pegau, A. H. Barnard, and J. R. V. Zaneveld, “A model for estimating bulk refractive index from the optical backscattering ratio and the implications for understanding particle composition in case I and case II waters,” J. Geophys. Res. 106(C7), 14129–14142 (2001).
[Crossref]

S. J. Chipera and D. L. Bish, “Baseline studies of the clay minerals society source clays: powder X-ray diffraction analyses,” Clays Clay Miner. 49(5), 398–409 (2001).
[Crossref]

2000 (2)

D. E. Walling, P. N. Owens, B. D. Waterfall, G. J. Leeks, and P. D. Wass, “The particle size characteristics of fluvial suspended sediment in the Humber and Tweed catchments, UK,” Sci. Total Environ. 251-252, 205–222 (2000).
[Crossref] [PubMed]

R. A. Leathers, T. V. Downes, and C. O. Davis, “Analysis of a point-source integrating-cavity absorption meter,” Appl. Opt. 39(33), 6118–6127 (2000).
[Crossref] [PubMed]

1999 (3)

C. D. Mobley, “Estimation of the remote-sensing reflectance from above-surface measurements,” Appl. Opt. 38(36), 7442–7455 (1999).
[Crossref] [PubMed]

P. Forget, S. Ouillon, F. Lahet, and P. Broche, “Inversion of reflectance spectra of nonchlorophyllous turbid coastal waters,” Remote Sens. Environ. 68(3), 264–272 (1999).
[Crossref]

G. F. Moore, J. Aiken, and S. J. Lavender, “The atmospheric correction of water colour and the quantitative retrieval of suspended particulate matter in Case II waters: Application to MERIS,” Int. J. Remote Sens. 20(9), 1713–1733 (1999).
[Crossref]

1998 (1)

P. Forget and S. Ouillon, “Surface suspended matter off the Rhône river mouth from visible satellite imagery,” Oceanol. Acta 21(6), 739–749 (1998).
[Crossref]

1997 (1)

J. T. Kirk, “Point-source integrating-cavity absorption meter: theoretical principles and numerical modeling,” Appl. Opt. 36(24), 6123–6128 (1997).
[Crossref] [PubMed]

1996 (2)

E. Aas, “Refractive index of phytoplankton derived from its metabolite composition,” J. Plankton Res. 18(12), 2223–2249 (1996).
[Crossref]

F. Eyrolle, M. F. Benedetti, J. Y. Benaim, and D. Fevrier, “The distributions of colloidal and dissolved organic carbon, major elements, and trace elements in small tropical catchments,” Geochim. Cosmochim. Acta 60(19), 3643–3656 (1996).
[Crossref]

1995 (2)

J. A. Marengo, “Variations and change in South American streamflow,” Clim. Change 31(1), 99–117 (1995).
[Crossref]

J. Buffle and G. G. Leppard, “Characterization of aquatic colloids and macromolecules. 1. Structure and behavior of colloidal material,” Environ. Sci. Technol. 29(9), 2169–2175 (1995).
[Crossref] [PubMed]

1992 (1)

J. A. Harrington, F. R. Schiebe, and J. F. Nix, “Remote sensing of Lake Chicot, Arkansas: Monitoring suspended sediments, turbidity, and Secchi depth with Landsat MSS data,” Remote Sens. Environ. 39(1), 15–27 (1992).
[Crossref]

1991 (3)

A. Morel and Y.-H. Ahn, “Optics of heterotrophic nanoflagellates and ciliates: A tentative assessment of their scattering role in oceanic waters compared to those of bacterial and algal cells,” J. Mar. Res. 49(1), 177–202 (1991).
[Crossref]

D. Stramski and D. A. Kiefer, “Light scattering by microorganisms in the open ocean,” Prog. Oceanogr. 28(4), 343–383 (1991).
[Crossref]

J. T. Kirk, “Volume scattering function, average cosines, and the underwater light field,” Limnol. Oceanogr. 36(3), 455–467 (1991).
[Crossref]

1989 (1)

J. E. Richey, C. Nobre, and C. Deser, “Amazon River discharge and climate variability: 1903 to 1985,” Science 246(4926), 101–103 (1989).
[Crossref] [PubMed]

1988 (1)

J. C. Ritchie and C. M. Cooper, “Comparison of measured suspended sediment concentrations with suspended sediment concentrations estimated from Landsat MSS data,” Int. J. Remote Sens. 9(3), 379–387 (1988).
[Crossref]

1984 (1)

W. De Rooij and C. Van der Stap, “Expansion of Mie scattering matrices in generalized spherical functions,” Astron. Astrophys. 131, 237–248 (1984).

1983 (1)

J. D. Milliman and R. H. Meade, “World-wide delivery of river sediment to the oceans,” J. Geol. 91(1), 1–21 (1983).
[Crossref]

1977 (2)

A. Morel and L. Prieur, “Analysis of variations in ocean color,” Limnol. Oceanogr. 22(4), 709–722 (1977).
[Crossref]

J. E. Harris, “Characterization of suspended matter in the Gulf of Mexico—II Particle size analysis of suspended matter from deep water,” Deep-Sea Res. 24(11), 1055–1061 (1977).
[Crossref]

1975 (1)

H. R. Gordon, O. B. Brown, and M. M. Jacobs, “Computed relationships between the inherent and apparent optical properties of a flat homogeneous ocean,” Appl. Opt. 14(2), 417–427 (1975).
[Crossref] [PubMed]

1970 (1)

H. Bader, “The hyperbolic distribution of particle sizes,” J. Geophys. Res. 75(15), 2822–2830 (1970).
[Crossref]

Aas, E.

E. Aas, “Refractive index of phytoplankton derived from its metabolite composition,” J. Plankton Res. 18(12), 2223–2249 (1996).
[Crossref]

Ahn, Y.-H.

Aiken, J.

Allen, P. A.

P. A. Allen, “From landscapes into geological history,” Nature 451(7176), 274–276 (2008).
[Crossref] [PubMed]

Alves, F. V.

Armijos, E.

Babin, M.

M. Babin and D. Stramski, “Variations in the mass-specific absorption coefficient of mineral particles suspended in water,” Limnol. Oceanogr. 49(3), 756–767 (2004).
[Crossref]

Bader, H.

H. Bader, “The hyperbolic distribution of particle sizes,” J. Geophys. Res. 75(15), 2822–2830 (1970).
[Crossref]

Baranya, S.

Baratange, F.

Barnard, A. H.

Beletsky, D.

Benaim, J. Y.

Benedetti, M. F.

Berthon, J.-F.

Bish, D. L.

S. J. Chipera and D. L. Bish, “Baseline studies of the clay minerals society source clays: powder X-ray diffraction analyses,” Clays Clay Miner. 49(5), 398–409 (2001).
[Crossref]

Boaventura, G. R.

J. L. Guyot, J. M. Jouanneau, L. Soares, G. R. Boaventura, N. Maillet, and C. Lagane, “Clay mineral composition of river sediments in the Amazon Basin,” Catena 71(2), 340–356 (2007).
[Crossref]

Bogucki, D.

D. Stramski, E. Boss, D. Bogucki, and K. J. Voss, “The role of seawater constituents in light backscattering in the ocean,” Prog. Oceanogr. 61(1), 27–56 (2004).
[Crossref]

Boss, E.

D. Stramski, E. Boss, D. Bogucki, and K. J. Voss, “The role of seawater constituents in light backscattering in the ocean,” Prog. Oceanogr. 61(1), 27–56 (2004).
[Crossref]

Bouchez, J.

Brando, V. E.

V. E. Brando and A. G. Dekker, “Satellite hyperspectral remote sensing for estimating estuarine and coastal water quality,” IEEE Trans. Geosci. Remote Sens. 41(6), 1378–1387 (2003).
[Crossref]

Breiman, L.

L. Breiman, “Random forests,” Mach. Learn. 45(1), 5–32 (2001).
[Crossref]

Bricaud, A.

Broche, P.

P. Forget, S. Ouillon, F. Lahet, and P. Broche, “Inversion of reflectance spectra of nonchlorophyllous turbid coastal waters,” Remote Sens. Environ. 68(3), 264–272 (1999).
[Crossref]

Brock, J. C.

Brown, O. B.

Bryère, P.

Budhiman, S.

Buffle, J.

Cai, L.

Callède, J.

Candiani, G.

Castaing, P.

Chami, M.

Chen, J.

Chen, S.

Chen, X.

Chen, Z.

Chipera, S. J.

S. J. Chipera and D. L. Bish, “Baseline studies of the clay minerals society source clays: powder X-ray diffraction analyses,” Clays Clay Miner. 49(5), 398–409 (2001).
[Crossref]

Claustre, H.

Clayton, T. D.

Cochonneau, G.

Cooper, C. M.

Cui, T.

D’Sa, E.

Dai, J.

R. Ma, J. Tang, J. Dai, Y. Zhang, and Q. Song, “Absorption and scattering properties of water body in Taihu Lake, China: absorption,” Int. J. Remote Sens. 27(19), 4277–4304 (2006).
[Crossref]

Davis, C. O.

R. A. Leathers, T. V. Downes, and C. O. Davis, “Analysis of a point-source integrating-cavity absorption meter,” Appl. Opt. 39(33), 6118–6127 (2000).
[Crossref] [PubMed]

de Oliveira, E.

De Rooij, W.

W. De Rooij and C. Van der Stap, “Expansion of Mie scattering matrices in generalized spherical functions,” Astron. Astrophys. 131, 237–248 (1984).

Dekker, A. G.

V. E. Brando and A. G. Dekker, “Satellite hyperspectral remote sensing for estimating estuarine and coastal water quality,” IEEE Trans. Geosci. Remote Sens. 41(6), 1378–1387 (2003).
[Crossref]

Deser, C.

J. E. Richey, C. Nobre, and C. Deser, “Amazon River discharge and climate variability: 1903 to 1985,” Science 246(4926), 101–103 (1989).
[Crossref] [PubMed]

Dessailly, D.

Doerffer, R.

Dogliotti, A. I.

Douillet, P.

Downes, T. V.

R. A. Leathers, T. V. Downes, and C. O. Davis, “Analysis of a point-source integrating-cavity absorption meter,” Appl. Opt. 39(33), 6118–6127 (2000).
[Crossref] [PubMed]

Doxaran, D.

Dubovik, O.

Dutra-Maia, P.

Eck, T. F.

Effler, S. W.

Eloheimo, K.

Espinoza Villar, J. C.

Espinoza-Villar, R.

Etcheber, H.

P. Moreira-Turcq, P. Seyler, J. L. Guyot, and H. Etcheber, “Exportation of organic carbon from the Amazon River and its main tributaries,” Hydrol. Processes 17(7), 1329–1344 (2003).
[Crossref]

Eyrolle, F.

Fernandez, J. M.

Ferrari, G. M.

Fevrier, D.

Filizola, N.

N. Filizola and J. L. Guyot, “Suspended sediment yields in the Amazon basin: an assessment using the Brazilian national data set,” Hydrol. Processes 23(22), 3207–3215 (2009).
[Crossref]

Forget, P.

P. Forget, S. Ouillon, F. Lahet, and P. Broche, “Inversion of reflectance spectra of nonchlorophyllous turbid coastal waters,” Remote Sens. Environ. 68(3), 264–272 (1999).
[Crossref]

P. Forget and S. Ouillon, “Surface suspended matter off the Rhône river mouth from visible satellite imagery,” Oceanol. Acta 21(6), 739–749 (1998).
[Crossref]

Fraizy, P.

France-Lanord, C.

Froidefond, J.-M.

J.-M. Froidefond and S. Ouillon, “Introducing a mini-catamaran to perform reflectance measurements above and below the water surface,” Opt. Express 13(3), 926–936 (2005).
[Crossref] [PubMed]

Gaillardet, J.

Gentili, B.

Giardino, C.

Gislason, S. R.

S. R. Gislason, E. H. Oelkers, and Á. Snorrason, “Role of river-suspended material in the global carbon cycle,” Geology 34(1), 49–52 (2006).
[Crossref]

Gordon, H. R.

Green, P.

Grunwald, M.

Guerrero, M.

Guimarães, V. S.

Guyot, J. L.

N. Filizola and J. L. Guyot, “Suspended sediment yields in the Amazon basin: an assessment using the Brazilian national data set,” Hydrol. Processes 23(22), 3207–3215 (2009).
[Crossref]

J. L. Guyot, J. M. Jouanneau, L. Soares, G. R. Boaventura, N. Maillet, and C. Lagane, “Clay mineral composition of river sediments in the Amazon Basin,” Catena 71(2), 340–356 (2007).
[Crossref]

P. Moreira-Turcq, P. Seyler, J. L. Guyot, and H. Etcheber, “Exportation of organic carbon from the Amazon River and its main tributaries,” Hydrol. Processes 17(7), 1329–1344 (2003).
[Crossref]

Guyot, J.-L.

Han, B.

Han, L.

Han, Z.

Z. Han, Y.-Q. Jin, and C.-X. Yun, “Suspended sediment concentrations in the Yangtze River estuary retrieved from the CMODIS data,” Int. J. Remote Sens. 27(19), 4329–4336 (2006).
[Crossref]

Hannonen, T.

Hanuš, J.

H. Vinciková, J. Hanuš, and L. Pechar, “Spectral reflectance is a reliable water-quality estimator for small, highly turbid wetlands,” Wetlands Ecol. Manage. 23(5), 933–946 (2015).
[Crossref]

Härmä, P.

Harrington, J. A.

Harris, J. E.

J. E. Harris, “Characterization of suspended matter in the Gulf of Mexico—II Particle size analysis of suspended matter from deep water,” Deep-Sea Res. 24(11), 1055–1061 (1977).
[Crossref]

Haun, S.

Hoepffner, N.

Holben, B.

Horowitz, A. J.

A. J. Horowitz, “Determining annual suspended sediment and sediment-associated trace element and nutrient fluxes,” Sci. Total Environ. 400(1-3), 315–343 (2008).
[Crossref] [PubMed]

Hu, C.

Jacobs, M. M.

Jin, Y.-Q.

Z. Han, Y.-Q. Jin, and C.-X. Yun, “Suspended sediment concentrations in the Yangtze River estuary retrieved from the CMODIS data,” Int. J. Remote Sens. 27(19), 4329–4336 (2006).
[Crossref]

Jintasaeranee, P.

Jouanneau, J. M.

J. L. Guyot, J. M. Jouanneau, L. Soares, G. R. Boaventura, N. Maillet, and C. Lagane, “Clay mineral composition of river sediments in the Amazon Basin,” Catena 71(2), 340–356 (2007).
[Crossref]

Jouon, A.

Kallio, K.

Kämäri, J.

Kaufman, Y. J.

Kerr, P.

P. Kerr, “Optical mineralogy, 492 pp,” (1977).

Kettner, A. J.

Kiefer, D. A.

D. Stramski and D. A. Kiefer, “Light scattering by microorganisms in the open ocean,” Prog. Oceanogr. 28(4), 343–383 (1991).
[Crossref]

King, M. D.

Kipp, P.-R.

Kirk, J. T.

J. T. Kirk, “Point-source integrating-cavity absorption meter: theoretical principles and numerical modeling,” Appl. Opt. 36(24), 6123–6128 (1997).
[Crossref] [PubMed]

J. T. Kirk, “Volume scattering function, average cosines, and the underwater light field,” Limnol. Oceanogr. 36(3), 455–467 (1991).
[Crossref]

Knaeps, E.

Kobayashi, H.

Koponen, S.

Korotaev, G.

Kostadinov, T. S.

T. S. Kostadinov, D. A. Siegel, and S. Maritorena, “Retrieval of the particle size distribution from satellite ocean color observations,” J. Geophys. Res. 114(C9), C09015 (2009).
[Crossref]

L’Hôte, Y.

Lagane, C.

J. L. Guyot, J. M. Jouanneau, L. Soares, G. R. Boaventura, N. Maillet, and C. Lagane, “Clay mineral composition of river sediments in the Amazon Basin,” Catena 71(2), 340–356 (2007).
[Crossref]

Lahet, F.

P. Forget, S. Ouillon, F. Lahet, and P. Broche, “Inversion of reflectance spectra of nonchlorophyllous turbid coastal waters,” Remote Sens. Environ. 68(3), 264–272 (1999).
[Crossref]

Lartiges, B.

S. Pinet, B. Lartiges, J.-M. Martinez, and S. Ouillon, “From SEM analysis to the mineralogical composition of suspended sediments in large river basin,” in preparation.

Latosinski, F.

Latrubesse, E. M.

E. M. Latrubesse, “Patterns of anabranching channels: The ultimate end-member adjustment of mega rivers,” Geomorphology 101(1-2), 130–145 (2008).
[Crossref]

Lavado, W.

Lavender, S.

Lavender, S. J.

Le Texier, M.

Leathers, R. A.

R. A. Leathers, T. V. Downes, and C. O. Davis, “Analysis of a point-source integrating-cavity absorption meter,” Appl. Opt. 39(33), 6118–6127 (2000).
[Crossref] [PubMed]

Lee, M.

Lee, Z.

Leeks, G. J.

Lefebvre, J. P.

Leppard, G. G.

Lesht, B. M.

Li, C.

Li, D.

Li, Y.

Lide, D.

D. Lide,

Lin, G.

Lirdwitayaprasit, T.

Loisel, H.

H. Loisel and A. Morel, “Non-isotropy of the upward radiance field in typical coastal (Case 2) waters,” Int. J. Remote Sens. 22(2-3), 275–295 (2001).
[Crossref]

Ma, R.

R. Ma, J. Tang, J. Dai, Y. Zhang, and Q. Song, “Absorption and scattering properties of water body in Taihu Lake, China: absorption,” Int. J. Remote Sens. 27(19), 4277–4304 (2006).
[Crossref]

Ma, X.

Macdonald, J. B.

Maillet, N.

J. L. Guyot, J. M. Jouanneau, L. Soares, G. R. Boaventura, N. Maillet, and C. Lagane, “Clay mineral composition of river sediments in the Amazon Basin,” Catena 71(2), 340–356 (2007).
[Crossref]

Marengo, J. A.

J. A. Marengo, “Variations and change in South American streamflow,” Clim. Change 31(1), 99–117 (1995).
[Crossref]

Mari, X.

Maritorena, S.

T. S. Kostadinov, D. A. Siegel, and S. Maritorena, “Retrieval of the particle size distribution from satellite ocean color observations,” J. Geophys. Res. 114(C9), C09015 (2009).
[Crossref]

Martinez, J. M.

Martinez, J.-M.

S. Pinet, B. Lartiges, J.-M. Martinez, and S. Ouillon, “From SEM analysis to the mineralogical composition of suspended sediments in large river basin,” in preparation.

Matsumura, S.

Maurice, L.

McKee, D.

Meade, R. H.

J. D. Milliman and R. H. Meade, “World-wide delivery of river sediment to the oceans,” J. Geol. 91(1), 1–21 (1983).
[Crossref]

Meneses, P. R.

Mériaux, X.

Milliman, J. D.

J. D. Milliman and R. H. Meade, “World-wide delivery of river sediment to the oceans,” J. Geol. 91(1), 1–21 (1983).
[Crossref]

Mobley, C. D.

C. D. Mobley, “Estimation of the remote-sensing reflectance from above-surface measurements,” Appl. Opt. 38(36), 7442–7455 (1999).
[Crossref] [PubMed]

Moore, G. F.

Moreira-Turcq, P.

P. Moreira-Turcq, P. Seyler, J. L. Guyot, and H. Etcheber, “Exportation of organic carbon from the Amazon River and its main tributaries,” Hydrol. Processes 17(7), 1329–1344 (2003).
[Crossref]

Morel, A.

H. Loisel and A. Morel, “Non-isotropy of the upward radiance field in typical coastal (Case 2) waters,” Int. J. Remote Sens. 22(2-3), 275–295 (2001).
[Crossref]

A. Morel and L. Prieur, “Analysis of variations in ocean color,” Limnol. Oceanogr. 22(4), 709–722 (1977).
[Crossref]

Muller-Karger, F. E.

Nechad, B.

Niel, H.

Nix, J. F.

Nobre, C.

J. E. Richey, C. Nobre, and C. Deser, “Amazon River discharge and climate variability: 1903 to 1985,” Science 246(4926), 101–103 (1989).
[Crossref] [PubMed]

O’Donnell, D.

Obolensky, G.

Oelkers, E. H.

S. R. Gislason, E. H. Oelkers, and Á. Snorrason, “Role of river-suspended material in the global carbon cycle,” Geology 34(1), 49–52 (2006).
[Crossref]

Ouillon, S.

J.-M. Froidefond and S. Ouillon, “Introducing a mini-catamaran to perform reflectance measurements above and below the water surface,” Opt. Express 13(3), 926–936 (2005).
[Crossref] [PubMed]

P. Forget, S. Ouillon, F. Lahet, and P. Broche, “Inversion of reflectance spectra of nonchlorophyllous turbid coastal waters,” Remote Sens. Environ. 68(3), 264–272 (1999).
[Crossref]

P. Forget and S. Ouillon, “Surface suspended matter off the Rhône river mouth from visible satellite imagery,” Oceanol. Acta 21(6), 739–749 (1998).
[Crossref]

S. Pinet, B. Lartiges, J.-M. Martinez, and S. Ouillon, “From SEM analysis to the mineralogical composition of suspended sediments in large river basin,” in preparation.

Owens, P. N.

Pechar, L.

H. Vinciková, J. Hanuš, and L. Pechar, “Spectral reflectance is a reliable water-quality estimator for small, highly turbid wetlands,” Wetlands Ecol. Manage. 23(5), 933–946 (2015).
[Crossref]

Pegau, W. S.

Peng, F.

Perkins, M. G.

Petersen, W.

Pinet, S.

S. Pinet, B. Lartiges, J.-M. Martinez, and S. Ouillon, “From SEM analysis to the mineralogical composition of suspended sediments in large river basin,” in preparation.

Piskozub, J.

Pokrovsky, O. S.

Pombosa, R.

Poteau, A.

Prieur, L.

A. Morel and L. Prieur, “Analysis of variations in ocean color,” Limnol. Oceanogr. 22(4), 709–722 (1977).
[Crossref]

Pulliainen, J.

Pyhälahti, T.

Reynolds, R. A.

Richey, J. E.

J. E. Richey, C. Nobre, and C. Deser, “Amazon River discharge and climate variability: 1903 to 1985,” Science 246(4926), 101–103 (1989).
[Crossref] [PubMed]

Ritchie, J. C.

Ronchail, J.

Röttgers, R.

Rouse, H.

H. Rouse,

Ruddick, K.

Ruddick, K. G.

Rüther, N.

Schiebe, F. R.

Schönfeld, W.

Schott, J.

Schwab, D. J.

Seyler, P.

P. Moreira-Turcq, P. Seyler, J. L. Guyot, and H. Etcheber, “Exportation of organic carbon from the Amazon River and its main tributaries,” Hydrol. Processes 17(7), 1329–1344 (2003).
[Crossref]

Shang, S.

Shybanov, E.

Siegel, D. A.

T. S. Kostadinov, D. A. Siegel, and S. Maritorena, “Retrieval of the particle size distribution from satellite ocean color observations,” J. Geophys. Res. 114(C9), C09015 (2009).
[Crossref]

Silva Moreira, L.

Siripong, A.

Slutsker, I.

Smirnov, A.

Snorrason, Á.

S. R. Gislason, E. H. Oelkers, and Á. Snorrason, “Role of river-suspended material in the global carbon cycle,” Geology 34(1), 49–52 (2006).
[Crossref]

Soares, L.

J. L. Guyot, J. M. Jouanneau, L. Soares, G. R. Boaventura, N. Maillet, and C. Lagane, “Clay mineral composition of river sediments in the Amazon Basin,” Catena 71(2), 340–356 (2007).
[Crossref]

Sondag, F.

Song, Q.

R. Ma, J. Tang, J. Dai, Y. Zhang, and Q. Song, “Absorption and scattering properties of water body in Taihu Lake, China: absorption,” Int. J. Remote Sens. 27(19), 4277–4304 (2006).
[Crossref]

Stein, M. L.

Stramski, D.

M. Babin and D. Stramski, “Variations in the mass-specific absorption coefficient of mineral particles suspended in water,” Limnol. Oceanogr. 49(3), 756–767 (2004).
[Crossref]

D. Stramski, E. Boss, D. Bogucki, and K. J. Voss, “The role of seawater constituents in light backscattering in the ocean,” Prog. Oceanogr. 61(1), 27–56 (2004).
[Crossref]

D. Stramski and D. A. Kiefer, “Light scattering by microorganisms in the open ocean,” Prog. Oceanogr. 28(4), 343–383 (1991).
[Crossref]

Strömbeck, N.

Stroud, J. R.

Suhyb Salama, M.

Sun, L.

Swarzenski, P.

Syvitski, J. P. M.

Szupiany, R.

Tailliez, D.

Tang, D.

Tang, J.

R. Ma, J. Tang, J. Dai, Y. Zhang, and Q. Song, “Absorption and scattering properties of water body in Taihu Lake, China: absorption,” Int. J. Remote Sens. 27(19), 4277–4304 (2006).
[Crossref]

Tanré, D.

Toratani, M.

Twardowski, M.

Twardowski, M. S.

Utschig, C.

Van der Stap, C.

W. De Rooij and C. Van der Stap, “Expansion of Mie scattering matrices in generalized spherical functions,” Astron. Astrophys. 131, 237–248 (1984).

Vantrepotte, V.

Vauchel, P.

Vekerdy, Z.

Vepsäläinen, J.

Verhoef, W.

Villar, R. E.

Vinciková, H.

H. Vinciková, J. Hanuš, and L. Pechar, “Spectral reflectance is a reliable water-quality estimator for small, highly turbid wetlands,” Wetlands Ecol. Manage. 23(5), 933–946 (2015).
[Crossref]

Vörösmarty, C. J.

Voss, K. J.

D. Stramski, E. Boss, D. Bogucki, and K. J. Voss, “The role of seawater constituents in light backscattering in the ocean,” Prog. Oceanogr. 61(1), 27–56 (2004).
[Crossref]

Walling, D.

Walling, D. E.

Wass, P. D.

Waterfall, B. D.

Weidemann, A.

Wiltshire, K. H.

Wollschläger, J.

Woodward, J.

Wozniak, S. B.

Wright, V. M.

Xing, Q.

Ylöstalo, P.

Yun, C.-X.

Z. Han, Y.-Q. Jin, and C.-X. Yun, “Suspended sediment concentrations in the Yangtze River estuary retrieved from the CMODIS data,” Int. J. Remote Sens. 27(19), 4329–4336 (2006).
[Crossref]

Zaneveld, J. R. V.

Zhang, X.

Zhang, Y.

R. Ma, J. Tang, J. Dai, Y. Zhang, and Q. Song, “Absorption and scattering properties of water body in Taihu Lake, China: absorption,” Int. J. Remote Sens. 27(19), 4277–4304 (2006).
[Crossref]

Zhu, J.

Adv. Space Res. (1)

Appl. Opt. (8)

C. D. Mobley, “Estimation of the remote-sensing reflectance from above-surface measurements,” Appl. Opt. 38(36), 7442–7455 (1999).
[Crossref] [PubMed]

J. T. Kirk, “Point-source integrating-cavity absorption meter: theoretical principles and numerical modeling,” Appl. Opt. 36(24), 6123–6128 (1997).
[Crossref] [PubMed]

R. A. Leathers, T. V. Downes, and C. O. Davis, “Analysis of a point-source integrating-cavity absorption meter,” Appl. Opt. 39(33), 6118–6127 (2000).
[Crossref] [PubMed]

Astron. Astrophys. (1)

W. De Rooij and C. Van der Stap, “Expansion of Mie scattering matrices in generalized spherical functions,” Astron. Astrophys. 131, 237–248 (1984).

Catena (2)

J. L. Guyot, J. M. Jouanneau, L. Soares, G. R. Boaventura, N. Maillet, and C. Lagane, “Clay mineral composition of river sediments in the Amazon Basin,” Catena 71(2), 340–356 (2007).
[Crossref]

Chem. Geol. (1)

Clays Clay Miner. (1)

S. J. Chipera and D. L. Bish, “Baseline studies of the clay minerals society source clays: powder X-ray diffraction analyses,” Clays Clay Miner. 49(5), 398–409 (2001).
[Crossref]

Clim. Change (1)

J. A. Marengo, “Variations and change in South American streamflow,” Clim. Change 31(1), 99–117 (1995).
[Crossref]

Deep-Sea Res. (1)

J. E. Harris, “Characterization of suspended matter in the Gulf of Mexico—II Particle size analysis of suspended matter from deep water,” Deep-Sea Res. 24(11), 1055–1061 (1977).
[Crossref]

Environ. Sci. Technol. (1)

Geochem. Geophys. Geosyst. (1)

Geochim. Cosmochim. Acta (1)

Geology (1)

S. R. Gislason, E. H. Oelkers, and Á. Snorrason, “Role of river-suspended material in the global carbon cycle,” Geology 34(1), 49–52 (2006).
[Crossref]

Geomorphology (1)

E. M. Latrubesse, “Patterns of anabranching channels: The ultimate end-member adjustment of mega rivers,” Geomorphology 101(1-2), 130–145 (2008).
[Crossref]

Geophysica (1)

Hydrol. Processes (3)

N. Filizola and J. L. Guyot, “Suspended sediment yields in the Amazon basin: an assessment using the Brazilian national data set,” Hydrol. Processes 23(22), 3207–3215 (2009).
[Crossref]

P. Moreira-Turcq, P. Seyler, J. L. Guyot, and H. Etcheber, “Exportation of organic carbon from the Amazon River and its main tributaries,” Hydrol. Processes 17(7), 1329–1344 (2003).
[Crossref]

Hydrol. Sci. J. (2)

IEEE Trans. Geosci. Remote Sens. (1)

V. E. Brando and A. G. Dekker, “Satellite hyperspectral remote sensing for estimating estuarine and coastal water quality,” IEEE Trans. Geosci. Remote Sens. 41(6), 1378–1387 (2003).
[Crossref]

Int. J. Climatol. (1)

Int. J. Remote Sens. (6)

Z. Han, Y.-Q. Jin, and C.-X. Yun, “Suspended sediment concentrations in the Yangtze River estuary retrieved from the CMODIS data,” Int. J. Remote Sens. 27(19), 4329–4336 (2006).
[Crossref]

H. Loisel and A. Morel, “Non-isotropy of the upward radiance field in typical coastal (Case 2) waters,” Int. J. Remote Sens. 22(2-3), 275–295 (2001).
[Crossref]

R. Ma, J. Tang, J. Dai, Y. Zhang, and Q. Song, “Absorption and scattering properties of water body in Taihu Lake, China: absorption,” Int. J. Remote Sens. 27(19), 4277–4304 (2006).
[Crossref]

ISPRS J. Photogramm. Remote Sens. (2)

J. Atmos. Ocean. Technol. (1)

J. Atmos. Sci. (1)

J. Exp. Mar. Biol. Ecol. (1)

J. Geol. (1)

J. D. Milliman and R. H. Meade, “World-wide delivery of river sediment to the oceans,” J. Geol. 91(1), 1–21 (1983).
[Crossref]

J. Geophys. Res. (6)

H. Bader, “The hyperbolic distribution of particle sizes,” J. Geophys. Res. 75(15), 2822–2830 (1970).
[Crossref]

T. S. Kostadinov, D. A. Siegel, and S. Maritorena, “Retrieval of the particle size distribution from satellite ocean color observations,” J. Geophys. Res. 114(C9), C09015 (2009).
[Crossref]

J. Geophys. Res.: Earth Surface (1)

J. Mar. Res. (1)

J. Plankton Res. (1)

E. Aas, “Refractive index of phytoplankton derived from its metabolite composition,” J. Plankton Res. 18(12), 2223–2249 (1996).
[Crossref]

J. S. Am. Earth Sci. (1)

Limnol. Oceanogr. (7)

A. Morel and L. Prieur, “Analysis of variations in ocean color,” Limnol. Oceanogr. 22(4), 709–722 (1977).
[Crossref]

J. T. Kirk, “Volume scattering function, average cosines, and the underwater light field,” Limnol. Oceanogr. 36(3), 455–467 (1991).
[Crossref]

M. Babin and D. Stramski, “Variations in the mass-specific absorption coefficient of mineral particles suspended in water,” Limnol. Oceanogr. 49(3), 756–767 (2004).
[Crossref]

Mach. Learn. (1)

L. Breiman, “Random forests,” Mach. Learn. 45(1), 5–32 (2001).
[Crossref]

Mar. Geol. (1)

Nature (1)

P. A. Allen, “From landscapes into geological history,” Nature 451(7176), 274–276 (2008).
[Crossref] [PubMed]

Ocean Dyn. (1)

Oceanol. Acta (1)

P. Forget and S. Ouillon, “Surface suspended matter off the Rhône river mouth from visible satellite imagery,” Oceanol. Acta 21(6), 739–749 (1998).
[Crossref]

Opt. Express (3)

J.-M. Froidefond and S. Ouillon, “Introducing a mini-catamaran to perform reflectance measurements above and below the water surface,” Opt. Express 13(3), 926–936 (2005).
[Crossref] [PubMed]

Prog. Oceanogr. (2)

D. Stramski and D. A. Kiefer, “Light scattering by microorganisms in the open ocean,” Prog. Oceanogr. 28(4), 343–383 (1991).
[Crossref]

D. Stramski, E. Boss, D. Bogucki, and K. J. Voss, “The role of seawater constituents in light backscattering in the ocean,” Prog. Oceanogr. 61(1), 27–56 (2004).
[Crossref]

Remote Sens. (1)

Remote Sens. Environ. (6)

P. Forget, S. Ouillon, F. Lahet, and P. Broche, “Inversion of reflectance spectra of nonchlorophyllous turbid coastal waters,” Remote Sens. Environ. 68(3), 264–272 (1999).
[Crossref]

Revue des sciences de l’eau (1)

Sci. Total Environ. (3)

A. J. Horowitz, “Determining annual suspended sediment and sediment-associated trace element and nutrient fluxes,” Sci. Total Environ. 400(1-3), 315–343 (2008).
[Crossref] [PubMed]

Science (2)

J. E. Richey, C. Nobre, and C. Deser, “Amazon River discharge and climate variability: 1903 to 1985,” Science 246(4926), 101–103 (1989).
[Crossref] [PubMed]

Water (1)

Water Resour. Res. (1)

Wetlands Ecol. Manage. (1)

H. Vinciková, J. Hanuš, and L. Pechar, “Spectral reflectance is a reliable water-quality estimator for small, highly turbid wetlands,” Wetlands Ecol. Manage. 23(5), 933–946 (2015).
[Crossref]

Other (16)

B. M. Fekete and C. J. Vörösmarty, “The current status of global river discharge monitoring and potential new technologies complementing traditional discharge measurements,” in Predictions in Ungauged Basins: PUB Kick-off (Proceedings of the PUB Kick-off Meeting Held in Brasilia, 20–22 November 2002). IAHS Publication (2002), Vol. 349.

M. Goulding, R. Barthem, and E. Ferreira, “The Smithsonian atlas of the Amazon,” Smithsonian Books, Washington and London, USA and UK. (2003).

S. Pinet, B. Lartiges, J.-M. Martinez, and S. Ouillon, “From SEM analysis to the mineralogical composition of suspended sediments in large river basin,” in preparation.

J.-P. Eberhart, Analyse Structurale et Chimique Des Matériaux (Dunod, 1989).

L. Kaufman and P. Rousseeuw, Clustering by Means of Medoids (North-Holland, 1987).

C. D. Mobley, Light and Water: Radiative Transfer in Natural Waters (Academic press, 1994).

C. E. Junge, “Air chemistry and radioactivity,” 1963 382 (1963).

M. Molinier, J. L. Guyot, J. Callède, E. De Oliveira, V. S. Guimarães, K. J. Cudo, and M. C. De Aquino, “Hidrologia de la cuenca amazonica Brasileira: HIBAM primeros resultados sobre la cuenca del rio Madeira - términos del balance hídrico. Metodologia,” 155–164 (1993).

N. G. Jerlov, Marine Optics (Elsevier, 1976), Vol. 14.

H. C. Van de Hulst, Light Scattering by Small Particles (Courier Corporation, 1957).

J. T. Kirk, Light and Photosynthesis in Aquatic Ecosystems (Cambridge University, 1994).

D. Lide,

P. Kerr, “Optical mineralogy, 492 pp,” (1977).

M. Boller and R. Kaegi, Characterization of Aquatic Particles (IWA Publishing, London, UK, 2011).

D. Walling and P. Moorehead, “The particle size characteristics of fluvial suspended sediment: an overview,” in Sediment/Water Interactions (Springer, 1989), pp. 125–149.

H. Rouse,

Cited By

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Fig. 1 Map of the Amazon River basin and of the Solimões and Madeira River tributaries (after Villar et al. [32]).

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Fig. 2 Data involved in the modeling process (inputs and outputs), or used to compared the simulated optical properties with in situ measurements and satellite data. Model calibration was based on field samplings (PSD, mineralogy and light absorption coefficient). Satellite data were retrieved from MODIS image time series following Villar et al. [32] in order to display the

R_{r s}

seasonal hysteresis as a function of SPM concentration, and to compare the reflectance estimates with the modeling outputs. They were not used for modeling calibration.

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Fig. 4 Mineralogy determined after SEM analysis for the Madeira River in March 2013 (left), and in December 2014 (right).

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Fig. 5 Relationships between SSCs and optical properties: a) in situ

R_{r s}

(850); b) band ratio between

R_{r s}

(850) and

R_{r s}

(670); c) in situ diffuse light attenuation coefficient

K_{d}

(670); d) in situ non-algal particulate matter absorption coefficient

a_{N A P}

(550).

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Fig. 6 Average monthly MODIS surface reflectances

R_{s}

(850) for 2000-2011 as a function of SSC on the Madeira River at the Porto Velho gauging station as retrieved by Villar et al. [32]. The numbers indicate the month from January (1) to December (12).

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Fig. 7 Spectral variations of the imaginary part

n^{'}

of the refraction index of the suspended particles. Data corresponding to Solimões River and Madeira River are mean values (standard deviations are represented by the error bars) obtained by mineralogical determination by SEM. Values extracted from Kobayashi et al. [11] and corresponding to the Bangpankong River estuary stand for the reference.

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Fig. 8 Monthly variations of

a_{N A P}

b_{N A P}

b_{b N A P}

at 5 wavelengths on the Madeira River. Annotations represent months from January (1) to December (12).

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Fig. 9 Variations between monthly means of the AOPs and the SSCs: a)

R_{r s}

(850); b)

K_{d}

(670); c) reflectances band ratio between 850 and 670 nm.

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Fig. 10 Comparison between the average monthly

R_{r s}

(850) retrieved from the MODIS data [32] and the simulations from the MMP integrating in situ measurements as inputs.

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Fig. 12 Evolution of

R_{r s}

(850) and

R_{r s}

(670) as a function of the imaginary part

n^{'}

of the refraction index for different

J_{2}

values (c.f. legend of each graphic) and two

n

values.

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Fig. 13 Variations in the simulated a)

R_{r s}

(850), b)

R_{r s}

(670) and c)

R_{r s}

(850)/

R_{r s}

(670) for various PSDs (through the slope

J_{2}

of the PSD for their finer particles) and for different values of

n

(the real part of the sediment refraction index).

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Tables (3)

Table 1 List of acronyms and symbols.

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Table 2 Ranges of the parameters measured at the 104 stations during the three field surveys.

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Table 3 Number (N_s) of optical and PSD measurements for each stream and average values of D₅₀, D₉₀ (in µm), and slopes of the PSDs (see Table 1 for symbols).

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Equations (23)

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N (D) = K \times D^{- J} .

R_{r s} (0^{+}, θ, ϕ, λ) = \frac{L_{w} (0^{+}, θ, ϕ, λ)}{E_{d} (0^{+}, ϕ, λ)} .

R_{r s} = \frac{L_{u} (λ) - ρ \times L_{d} (λ)}{E_{d} (λ)} .

a_{N A P} = a_{T O T} - a_{C D O M} .

C_{b} = \frac{\int_{D_{m i n}}^{D_{m a x}} Q_{b} (λ, D, n) (\frac{π D^{2}}{4}) N (D) d D}{\int_{D_{m i n}}^{D_{m a x}} N (D) d D},

C_{b b} = \frac{\int_{D_{m i n}}^{D_{m a x}} Q_{b b} (λ, D, n) (\frac{π D^{2}}{4}) N (D) d D}{\int_{D_{m i n}}^{D_{m a x}} N (D) d D},

C_{b b} = \frac{\int_{D_{m i n}}^{D_{m a x}} Q_{b b} (λ, D, n) (\frac{π D^{2}}{4}) N (D) d D}{\int_{D_{m i n}}^{D_{m a x}} N (D) d D},

C_{a} = \frac{\int_{D_{m i n}}^{D_{m a x}} Q_{a} (λ, D, n) (\frac{π D^{2}}{4}) N (D) d D}{\int_{D_{m i n}}^{D_{m a x}} N (D) d D},

G = \frac{π}{4} \frac{\int_{D_{m i n}}^{D_{m a x}} D ² N (D) d D}{\int_{D_{m i n}}^{D_{m a x}} N (D) d D},

{\bar{Q}}_{b} = \frac{C_{b}}{G},

{\bar{Q}}_{b b} = \frac{C_{b b}}{G},

b_{N A P}^{*} = \frac{3 {\bar{Q}}_{b}}{2 ρ^{'}} \int_{D_{m i n}}^{D_{m a x}} N (D) D ² d D {(\int_{D_{m i n}}^{D_{m a x}} N (D) D^{3} d D)}^{- 1},

b_{b N A P}^{*} = \frac{3 {\bar{Q}}_{b b}}{2 ρ^{'}} \int_{D_{m i n}}^{D_{m a x}} N (D) D ² d D {(\int_{D_{m i n}}^{D_{m a x}} N (D) D^{3} d D)}^{- 1},

a_{N A P}^{*} = \frac{3 {\bar{Q}}_{a}}{2 ρ^{'}} \int_{D_{m i n}}^{D_{m a x}} N (D) D ² d D {(\int_{D_{m i n}}^{D_{m a x}} N (D) D^{3} d D)}^{- 1} .

R (0^{-}) = f^{'} \times \frac{b_{b T O T}}{a_{T O T} + b_{b T O T}},

K_{d} = \sqrt{a_{T O T}^{2} + (G' \times a_{T O T} \times b_{T O T})},

R_{r s} = \frac{t}{n_{w a t e r} ²} \times \frac{f'}{Q} \times \frac{b_{b T O T}}{a_{T O T} + b_{b T O T}} .

b_{T O T} = b_{W} + b_{N A P} + b_{C D O M} + b_{P H Y},

b_{b T O T} = b_{b W} + b_{b N A P} + b_{b C D O M} + b_{b P H Y},

a_{T O T} = a_{W} + a_{N A P} + a_{C D O M} + a_{P H Y} .

R (0^{-}) = f^{'} \times \frac{b_{b N A P}}{a_{W} + a_{N A P} + a_{C D O M} + b_{b N A P}},

K_{d} = \sqrt{(a_{W} + a_{N A P} + a_{C D O M}) ² + G' \times (a_{W} + a_{N A P} + a_{C D O M}) \times b_{N A P})},

R_{r s} = \frac{t}{n_{w a t e r} ²} \times \frac{f^{'}}{Q} \times \frac{b_{b N A P}}{a_{W} + a_{N A P} + a_{C D O M} + b_{b N A P}} .

Symbol	Definition	Unit
a_CDOM	absorption coefficient by CDOM	m⁻¹
a_NAP*	mass-specific absorption coefficient	m² mg⁻¹
a_NAP	absorption coefficient by non-algal particles	m⁻¹
AOP	apparent optical property	-
a_PHY	absorption coefficient by phytoplankton	m⁻¹
a_TOT	total absorption coefficient	m⁻¹
a_W	absorption coefficient by water molecules	m⁻¹
b_bNAP*	mass-specific backscattering coefficient	m² mg⁻¹
b_bNAP	backscattering coefficient by non-algal particles	m⁻¹
b_bPHY	backscattering coefficient by phytoplankton	m⁻¹
b_bTOT	total backscattering coefficient	m⁻¹
b_bW	backscattering coefficient by water molecules	m⁻¹
b_NAP*	mass-specific scattering coefficient	m² mg⁻¹
b_NAP	scattering coefficient by non-algal particles	m⁻¹
b_PHY	scattering coefficient by phytoplankton	m⁻¹
b_TOT	total scattering coefficient	m⁻¹
b_W	scattering coefficient by water molecules	m⁻¹
C_a	average cross section absorption	m²
C_bb	average cross section backscattering	m²
C_b	average cross section scattering	m²
CDOM	colored dissolved organic matter	-
D	diameter of particles	µm
D₅₀	median particle size distribution	µm
DOC	dissolved organic carbon	-
E_d	downwelling irradiance	W m⁻²
E_u	upwelling irradiance	W m⁻²
f'	factor of environmental conditions	dimensionless
G	average geometrical cross-section	m²
G'	coefficient of relative contribution of scattering to attenuation	dimensionless
IOP	inherent optical property	-
J	Junge's parameter as the slope of the PSD in log-log representation	dimensionless
J₁	for size classes lower than 10 µm	dimensionless
J₂	for size classes greater than 10 µm	dimensionless
J_TOT	for all size classes	dimensionless
K	coefficient of PSD
K_d	diffuse light attenuation coefficient	m⁻¹
L_d	downwelling radiance	W m⁻² sr⁻¹
L_u	upwelling radiance	W m⁻² sr⁻¹
L_w	water leaving radiance	W m⁻² sr⁻¹
λ	wavelengths	nm
MMP	Meerhoff Mie program	-
n	real part of the refraction index	dimensionless
n_water	refraction index of the water	dimensionless
n'	imaginary part of the refraction index	dimensionless
N	number of particles
NAP	non-algal particle	-
NIR	near infra-red	-
PAM	partitioning around medoids	-
POC	particular organic carbon	-
PSD	particle size distribution	-
PSICAM	point source integrating cavity absorption meter	-
Q	anisotropy factor	sr
Q_a	absorption efficiency factor (individual particle)	dimensionless
Q͞_a	absorption efficiency factor (entire particle population)	dimensionless
Q_bb	backscattering efficiency factor (individual particle)	dimensionless
Q͞_bb	backscattering efficiency factor (entire particle population)	dimensionless
Q_b	scattering efficiency factor (individual particle)	dimensionless
Q͞_b	scattering efficiency factor (entire particle population)	dimensionless
R	irradiance reflectance under the water surface	dimensionless
R_rs	remote sensing reflectance above the water surface	sr⁻¹
R_s	surface reflectance	sr⁻¹
RMSE	root mean squared error	-
ρ	skyglint correction factor	dimensionless
ρ'	density of mineral particles	dimensionless
SSC	suspended sediment concentration	-
SEM	scanning electron microscopy	-
σ	standard deviation
t	radiance transmittance at the air-water interface	dimensionless
θ	zenithal angle from the nadir	rad
z, z₁, z₂	depth under the water surface	m

Dates	Stations	Turbidity range (NTU)	SSC range (mg l⁻¹)	R_rs(850) range (sr⁻¹ x1000)	K_d(670) range (m⁻¹)	a_NAP(550) range (m⁻¹)	POC range (%)
09-12 Mar 2013	16	3.85 / 756	10.3 / 535.4	1.58 / 30.40	2.51 / 21.95	0.39 / 7.20	0.84 / 41.20
02-23 Apr 2014	47	3.37 / 320	1.6 / 303.8	0.25 / 18.25	3.19 / 14.62	0.50 / 5.26	0.44 / 62.11
02-15 Dec 2014	41	6.82 / 760	3.2 / 774.8	0.59 / 39.21	3.56 / 20.22	0.24 / 7.66	0.20 / 14.12

	Particle size distribution						R_rs	K_d	a_TOT/a_CDOM/a_NAP
	N_s	D₅₀	D₉₀	*J_TOT*	J₁	J₂	N_s	N_s	N_s
Rio Solimões	32	14.55	68.31	2.777	2.105	3.517	11	12	31
Rio Madeira	35	6.68	32.51	3.290	2.443	4.054	15	11	43
Rio Amazonas	11	10.47	45.28	2.995	2.271	3.893	5	5	14
Tributaries	7	11.90	50.08	2.838	1.883	3.862	10	11	16
Total	85	10.61	45.28	3.006	2.180	3.856	41	39	104

Symbol	Definition	Unit
a_CDOM	absorption coefficient by CDOM	m⁻¹
a_NAP*	mass-specific absorption coefficient	m² mg⁻¹
a_NAP	absorption coefficient by non-algal particles	m⁻¹
AOP	apparent optical property	-
a_PHY	absorption coefficient by phytoplankton	m⁻¹
a_TOT	total absorption coefficient	m⁻¹
a_W	absorption coefficient by water molecules	m⁻¹
b_bNAP*	mass-specific backscattering coefficient	m² mg⁻¹
b_bNAP	backscattering coefficient by non-algal particles	m⁻¹
b_bPHY	backscattering coefficient by phytoplankton	m⁻¹
b_bTOT	total backscattering coefficient	m⁻¹
b_bW	backscattering coefficient by water molecules	m⁻¹
b_NAP*	mass-specific scattering coefficient	m² mg⁻¹
b_NAP	scattering coefficient by non-algal particles	m⁻¹
b_PHY	scattering coefficient by phytoplankton	m⁻¹
b_TOT	total scattering coefficient	m⁻¹
b_W	scattering coefficient by water molecules	m⁻¹
C_a	average cross section absorption	m²
C_bb	average cross section backscattering	m²
C_b	average cross section scattering	m²
CDOM	colored dissolved organic matter	-
D	diameter of particles	µm
D₅₀	median particle size distribution	µm
DOC	dissolved organic carbon	-
E_d	downwelling irradiance	W m⁻²
E_u	upwelling irradiance	W m⁻²
f'	factor of environmental conditions	dimensionless
G	average geometrical cross-section	m²
G'	coefficient of relative contribution of scattering to attenuation	dimensionless
IOP	inherent optical property	-
J	Junge's parameter as the slope of the PSD in log-log representation	dimensionless
J₁	for size classes lower than 10 µm	dimensionless
J₂	for size classes greater than 10 µm	dimensionless
J_TOT	for all size classes	dimensionless
K	coefficient of PSD
K_d	diffuse light attenuation coefficient	m⁻¹
L_d	downwelling radiance	W m⁻² sr⁻¹
L_u	upwelling radiance	W m⁻² sr⁻¹
L_w	water leaving radiance	W m⁻² sr⁻¹
λ	wavelengths	nm
MMP	Meerhoff Mie program	-
n	real part of the refraction index	dimensionless
n_water	refraction index of the water	dimensionless
n'	imaginary part of the refraction index	dimensionless
N	number of particles
NAP	non-algal particle	-
NIR	near infra-red	-
PAM	partitioning around medoids	-
POC	particular organic carbon	-
PSD	particle size distribution	-
PSICAM	point source integrating cavity absorption meter	-
Q	anisotropy factor	sr
Q_a	absorption efficiency factor (individual particle)	dimensionless
Q͞_a	absorption efficiency factor (entire particle population)	dimensionless
Q_bb	backscattering efficiency factor (individual particle)	dimensionless
Q͞_bb	backscattering efficiency factor (entire particle population)	dimensionless
Q_b	scattering efficiency factor (individual particle)	dimensionless
Q͞_b	scattering efficiency factor (entire particle population)	dimensionless
R	irradiance reflectance under the water surface	dimensionless
R_rs	remote sensing reflectance above the water surface	sr⁻¹
R_s	surface reflectance	sr⁻¹
RMSE	root mean squared error	-
ρ	skyglint correction factor	dimensionless
ρ'	density of mineral particles	dimensionless
SSC	suspended sediment concentration	-
SEM	scanning electron microscopy	-
σ	standard deviation
t	radiance transmittance at the air-water interface	dimensionless
θ	zenithal angle from the nadir	rad
z, z₁, z₂	depth under the water surface	m

Dates	Stations	Turbidity range (NTU)	SSC range (mg l⁻¹)	R_rs(850) range (sr⁻¹ x1000)	K_d(670) range (m⁻¹)	a_NAP(550) range (m⁻¹)	POC range (%)
09-12 Mar 2013	16	3.85 / 756	10.3 / 535.4	1.58 / 30.40	2.51 / 21.95	0.39 / 7.20	0.84 / 41.20
02-23 Apr 2014	47	3.37 / 320	1.6 / 303.8	0.25 / 18.25	3.19 / 14.62	0.50 / 5.26	0.44 / 62.11
02-15 Dec 2014	41	6.82 / 760	3.2 / 774.8	0.59 / 39.21	3.56 / 20.22	0.24 / 7.66	0.20 / 14.12

Abstract

1. Introduction

2. Materials and methods

2.1 Study area

2.2 Sampling

2.3 Radiometric data

2.4 Modeling

2.4.1 Theoretical background

2.4.2 Model parametrization

3. Results

3.1 Grain size distribution

3.2 Mineralogy

3.3 Radiometry

3.4 Modeling

3.4.1 IOP variability during the hydrological cycle

3.4.1 Seasonal variations in the AOP

4. Discussion

4.1 PSDs

4.2 Hysteresis of the Rrs– SSC relationship

4.3 On the relative importance of n and PSD over the IOPs

4.4 On the relative importance of n, n'and PSD over the AOPs

5. Conclusion

Funding

Acknowledgments

References and links

References

2016 (3)

2015 (5)

2014 (2)

2013 (5)

2012 (1)

2011 (2)

2010 (2)

2009 (6)

2008 (4)

2007 (7)

2006 (3)

2005 (4)

2004 (6)

2003 (3)

2002 (3)

2001 (5)

2000 (2)

1999 (3)

1998 (1)

1997 (1)

1996 (2)

1995 (2)

1992 (1)

1991 (3)

1989 (1)

1988 (1)

1984 (1)

1983 (1)

1977 (2)

1975 (1)

1970 (1)

Aas, E.

Ahn, Y.-H.

Aiken, J.

Allen, P. A.

Alves, F. V.

Armijos, E.

Babin, M.

Bader, H.

Baranya, S.

Baratange, F.

Barnard, A. H.

Beletsky, D.

Benaim, J. Y.

Benedetti, M. F.

Berthon, J.-F.

Bish, D. L.

Boaventura, G. R.

Bogucki, D.

Boss, E.

Bouchez, J.

Brando, V. E.

Breiman, L.

Bricaud, A.

4.2 Hysteresis of the $R_{r s}$ – SSC relationship

4.4 On the relative importance of $n$ , $n^{'}$ and PSD over the AOPs