Suspended particulate matter in the St. Lawrence estuary and Gulf surface layer and development of a remote sensing algorithm

Larouche, Pierre; Boyer-Villemaire, Ursule

doi:10.1016/j.ecss.2010.09.005

Cited by 17 publications

(7 citation statements)

References 13 publications

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“…Rrs being a function of both absorption and backscattering, its variations are thus regulated by spectral variations of inherent optical properties [63]. Backscattering should not show strong variations in the SLEG due to very low SPM concentrations [44], leaving absorption as the primary source of spectral variability. The work in [47] showed the contributions from different optical components to the absorption spectrum based on 371 in situ surface absorption measurements from all the major ocean basins.…”

Section: Discussionmentioning

confidence: 99%

“…According to [39], the standard NIR-iteration atmospheric correction (AC) procedure [40][41][42] is more suited to CDOM-dominated waters than the Management Unit of the North Sea Mathematical Models (MUMM) AC [43], which was developed for turbid waters dominated by mineral particles. Considering the low concentration of suspended particulate matter (SPM) measured over most of the SLEG [44], the standard NIR-iteration AC was used to process the SeaWiFS images. …”

Section: Atmospheric Correctionmentioning

confidence: 99%

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Chlorophyll-a Concentration Retrieval in the Optically Complex Waters of the St. Lawrence Estuary and Gulf Using Principal Component Analysis

Laliberté¹,

Larouche²,

Devred

et al. 2018

Remote Sensing

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Abstract:Empirical methods based on band ratios to infer chlorophyll-a concentration by satellite do not perform well over the optically complex waters of the St. Lawrence Estuary and Gulf. Using a dataset of 93 match-ups, we explore an alternative method relying on empirical orthogonal functions (EOF) to develop an algorithm that relates the satellite-derived remote sensing reflectances to in situ chlorophyll-a concentration for the Sea-viewing Wide Field-of-view Sensor (SeaWiFS). Results show that an accuracy of 41% at retrieving chlorophyll-a concentration can be reached using the EOF method compared to 140% for the widely-used Ocean Chlorophyll 4 (OC4v4) empirical algorithm, 53% for the Garver-Siegel-Maritorena (GSM01) and 54% for the Generalized Inherent Optical Property (GIOP) semi-analytical algorithms. This result is possible because the EOF approach is able to extract region-specific radiometric features from the satellite remote sensing reflectances that are related to absorption properties of optical components (water, coloured dissolved organic matter and chlorophyll-a) using the visible SeaWiFS channels. The method could easily be used with other ocean-colour satellite sensors (e.g., MODIS, MERIS, VIIRS, OLCI) to extend the time series for the St. Lawrence Estuary and Gulf waters.

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Section: Discussionmentioning

confidence: 99%

Section: Atmospheric Correctionmentioning

confidence: 99%

Chlorophyll-a Concentration Retrieval in the Optically Complex Waters of the St. Lawrence Estuary and Gulf Using Principal Component Analysis

Laliberté¹,

Larouche²,

Devred

et al. 2018

Remote Sensing

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“…In the surface waters of SF and during spring, Chanut and Poulet (1982) found that SPM is commonly composed of very small particles (i.e., 2-3 µm). Several investigations point out that suspended particulates in the SLE-SF regions are principally composed of inorganic matter (D'Anglejan and Smith, 1973;Larouche and Boyer-Villemaire, 2010;Mohammadpour et al, 2015). This mineral contribution may vary between 60 and 95 % of dry weight depending on the geographic location and period of the year (Yeats, 1988;Larouche and BoyerVillemaire, 2010).…”

Section: Study Areamentioning

confidence: 99%

Optical properties of size fractions of suspended particulate matter in littoral waters of Québec

Mohammadpour

Gagné

Larouche³

et al. 2017

Biogeosciences

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Abstract. Mass-specific absorption (a i * (λ)) and scattering (b i * (λ)) coefficients were derived for four size fractions (i = 0.2-0.4, 0.4-0.7, 0.7-10, and > 10 µm, λ = wavelength in nm) of suspended particulate matter (SPM) and with samples obtained from surface waters (i.e., 0-2 m depth) of the Saint Lawrence Estuary and Saguenay Fjord (SLE-SF) during June of 2013. For the visible-near-infrared spectral range (i.e., λ = 400-710 nm), mass-specific absorption coefficients of total SPM (i.e., particulates > 0.2 µm) (hereafter a SPM * ) had low values (e.g., < 0.01 m 2 g −1 at λ = 440 nm) in areas of the lower estuary dominated by particle assemblages with relatively large mean grain size and high particulate organic carbon and chlorophyll a per unit of mass of SPM. Conversely, largest a SPM * values (i.e., > 0.05 m 2 g −1 at λ = 440 nm) corresponded with locations of the upper estuary and SF where particulates were mineral-rich and/or their mean diameter was relatively small. The variability of two optical proxies (the spectral slope of particulate beam attenuation coefficient and the mass-specific particulate absorption coefficient, hereafter γ and Svis, respectively) with respect to changes in particle size distribution (PSD) and chemical composition was also examined. The slope of the PSD was correlated with b i * (550) (Spearman rank correlation coefficient ρ s up to 0.37) and a i * (440) estimates (ρ s up to 0.32) in a comparable way. Conversely, the contribution of particulate inorganic matter to total mass of SPM (F SPM PIM ) had a stronger correlation with a i * coefficients at a wavelength of 440 nm (ρ s up to 0.50). The magnitude of γ was positively related to F SPM i or the contribution of size fraction i to the total mass of SPM (ρ s up to 0.53 for i = 0.2-0.4 µm). Also, the relation between γ and F SPM PIM variability was secondary (ρ s = −0.34, P > 0.05). Lastly, the magnitude of Svis was inversely correlated with a SPM * (440) (ρ s = −0.55, P = 0.04) and F SPM PIM (ρ s = −0.62, P = 0.018) in sampling locations with a larger marine influence (i.e., lower estuary).

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“…Dans l'estuaire maritime, la matière en suspension est distribuée en trois couches avec une couche de surface riche en matière particulaire, une couche plus turbide au fond et une couche intermédiaire pauvre en matières en suspension (d'Anglejan et Smith 1973 ;Kranck 1979 ;Poulet et al 1986). Dans la couche de surface de l'estuaire maritime, il existe une variabilité spatiale des concentrations de particules en suspension qui résulte de l'écoulement des eaux provenant de l'estuaire moyen le long de la rive sud de l'estuaire ainsi que de la présence des panaches des rivières Manicouagan et Outardes sur la rive nord (Kranck 1979 ;Larouche et Boyer-Villemaire 2010). Ces panaches semblent aussi favoriser une plus grande concentration de particules organiques en intensifiant la stratification de la colonne d'eau ou en injectant des substances nutritives.…”

Section: R a F Tunclassified

Le concept d’approche écosystémique appliqué à l’estuaire maritime du Saint-Laurent (Canada)

et al. 2017

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Suspended particulate matter in the St. Lawrence estuary and Gulf surface layer and development of a remote sensing algorithm

Cited by 17 publications

References 13 publications

Chlorophyll-a Concentration Retrieval in the Optically Complex Waters of the St. Lawrence Estuary and Gulf Using Principal Component Analysis

Chlorophyll-a Concentration Retrieval in the Optically Complex Waters of the St. Lawrence Estuary and Gulf Using Principal Component Analysis

Optical properties of size fractions of suspended particulate matter in littoral waters of Québec

Le concept d’approche écosystémique appliqué à l’estuaire maritime du Saint-Laurent (Canada)

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