OPTICAL REMOTE SENSING TECHNIQUES TO ESTIMATE PHYTOPLANKTON CHLOROPHYLL a CONCENTRATIONS IN COASTAL

Schalles, John F.

doi:10.1007/1-4020-3968-9_3

Cited by 104 publications

(104 citation statements)

References 72 publications

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“…Indeed, the highest possible accuracy of the hyperspectral water-leaving reflectance improves the detection capability of the dedicated algorithms for the retrieval of water quality parameters (Chlorophyll, Total Suspended Matter and Colored Dissolved Organic Matter) (Gitelson et al, 2011;Lee et al, 2007;Zibordi et al, 2011;Giardino et al, 2010;Guanter et al, 2010;Brando and Dekker, 2003). For example, if the chl a concentration is estimated according to band-ratio, which makes use of a red (680 nm) to very near-infrared (700 nm) wavelengths, the advantage of having a signal on a contiguous spectrum relies on the possibility of defining the algorithm according to the shift of the near-infrared reflectance band to be used (Schalles, 2006). In case of spectral inversion procedures, a hyperspectral data set can facilitate a physics-based modelling approach to quantitatively retrieve multiple constituents of interest (e.g.…”

Section: Discussionmentioning

confidence: 99%

The impact of the microphysical properties of aerosol on the atmospheric correction of hyperspectral data in coastal waters

et al. 2015

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Abstract.Hyperspectral imaging provides quantitative remote sensing of ocean colour by the high spectral resolution of the water features. The HICO ™ (Hyperspectral Imager for the Coastal Ocean) is suitable for coastal studies and monitoring. The accurate retrieval of hyperspectral waterleaving reflectance from HICO ™ data is still a challenge. The aim of this work is to retrieve the water-leaving reflectance from HICO ™ data with a physically based algorithm, using the local microphysical properties of the aerosol in order to overcome the limitations of the standard aerosol types commonly used in atmospheric correction processing. The water-leaving reflectance was obtained using the HICO@CRI (HICO ATmospherically Corrected Reflectance Imagery) atmospheric correction algorithm by adapting the vector version of the Second Simulation of a Satellite Signal in the Solar Spectrum (6SV) radiative transfer code. The HICO@CRI algorithm was applied on to six HICO ™ images acquired in the northern Mediterranean basin, using the microphysical properties measured by the Acqua Alta Oceanographic Tower (AAOT) AERONET site. The HICO@CRI results obtained with AERONET products were validated with in situ measurements showing an accuracy expressed by r 2 = 0.98. Additional runs of HICO@CRI on the six images were performed using maritime, continental and urban standard aerosol types to perform the accuracy assessment when standard aerosol types implemented in 6SV are used. The results highlight that the microphysical properties of the aerosol improve the accuracy of the atmospheric correction compared to standard aerosol types. The normalized root mean square (NRMSE) and the similar spectral value (SSV) of the water-leaving reflectance show reduced accuracy in atmospheric correction results when there is an increase in aerosol loading. This is mainly when the standard aerosol type used is characterized with different optical properties compared to the local aerosol. The results suggest that if a water quality analysis is needed the microphysical properties of the aerosol need to be taken into consideration in the atmospheric correction of hyperspectral data over coastal environments, because aerosols influence the accuracy of the retrieved water-leaving reflectance.

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Section: Discussionmentioning

confidence: 99%

The impact of the microphysical properties of aerosol on the atmospheric correction of hyperspectral data in coastal waters

et al. 2015

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“…The first uses a ratio of reflectance in the wavelength range between 440 and 510 nm in which Chl-a and carotenoid strongly absorb light and another reflectance in the minimum green pigment region between 550 and 555 nm [21,35]. The second uses a ratio of reflectance in the near-infrared (NIR) region between 685 and 710 nm, in which the water and pigment absorption and the chlorophyll fluorescence have a minimum correlation, and another reflectance in the red chlorophyll absorption band between 670 and 675 nm [4,36].…”

Section: Review Of Estimation Algorithmsmentioning

confidence: 99%

“…This simple ratio has a robust and sensitive relationship to the Chl-a concentration in ocean waters, but is known to be less sensitive for the 30 mg/m 3 or more of Chl-a [4]. The algorithm has been improved in order to make it applicable to coastal waters [7][8][9]35,37,38].…”

Section: Review Of Estimation Algorithmsmentioning

confidence: 99%

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Improved Accuracy of Chlorophyll-a Concentration Estimates from MODIS Imagery Using a Two-Band Ratio Algorithm and Geostatistics: As Applied to the Monitoring of Eutrophication Processes over Tien Yen Bay (Northern Vietnam)

Koike

Nhuận

2013

Remote Sensing

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Sea eutrophication is a natural process of water enrichment caused by increased nutrient loading that severely affects coastal ecosystems by decreasing water quality. The degree of eutrophication can be assessed by chlorophyll-a concentration. This study aims to develop a remote sensing method suitable for estimating chlorophyll-a concentrations in tropical coastal waters with abundant phytoplankton using Moderate Resolution Imaging Spectroradiometer (MODIS)/Terra imagery and to improve the spatial resolution of MODIS/Terra-based estimation from 1 km to 100 m by geostatistics. A model based on the ratio of green and blue band reflectance (rGBr) is proposed considering the bio-optical property of chlorophyll-a. Tien Yen Bay in northern Vietnam, a typical phytoplankton-rich coastal area, was selected as a case study site. The superiority of rGBr over two existing representative models, based on the blue-green band ratio and the red-near infrared band ratio, was demonstrated by a high correlation of the estimated chlorophyll-a concentrations at 40 sites with values measured in situ. Ordinary kriging was then shown to be highly capable of predicting the concentration for regions of the image covered by clouds and, thus, without sea surface data. Resultant space-time maps of concentrations over a year clarified that Tien Yen Bay is characterized by natural eutrophic waters, because the average of chlorophyll-a concentrations exceeded 10 mg/m 3 in the summer. The temporal changes of chlorophyll-a concentrations were consistent with average monthly air

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“…The success of this application will depend largely on the resolution of the satellite data that the algorithm 30 is applied to, the accuracy of the algorithm itself and the ability to quantify associated errors, increasing the need for high quality in situ measurements. Satellite observations are vulnerable to inaccuracies in coastal waters due to factors including cloud cover, the presence of coloured dissolved organic matter (CDOM) and suspended sediments, the presence of both marine and terrestrial aerosols, land adjacency effects, and the electromagnetic complexity of coastal signals (in both optical and radio wave spectrum) (Schalles, 2006;Land et al, 2015). 35 Future planned sensors with higher spatial and spectral resolution may help reduce these current limitations.…”

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confidence: 99%

Estimating total alkalinity for coastal ocean acidification monitoring at regional to continental scales in Australian coastal waters

Baldry

Hardman-Mountford

Greenwood

2017

Preprint

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Abstract.Owing to a lack of resources, tools, and knowledge, the natural variability and distribution of Total Alkalinity (TA) has been poorly characterised in coastal waters globally, yet variability is known to be high in coastal regions due to the complex interactions of oceanographic, biotic, and terrestrially-influenced processes. This is a 5 particularly challenging task for the vast Australian coastline, however, it is also this vastness that demands attention in the face of ocean acidification (OA). Australian coastal waters have high biodiversity and endemism, and are home to large areas of coral reef, including the Great Barrier Reef, the largest coral reef system in the world. Ocean acidification threatens calcifying marine organisms by hindering calcification rates, Biogeosciences Discuss.,

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OPTICAL REMOTE SENSING TECHNIQUES TO ESTIMATE PHYTOPLANKTON CHLOROPHYLL a CONCENTRATIONS IN COASTAL

Cited by 104 publications

References 72 publications

The impact of the microphysical properties of aerosol on the atmospheric correction of hyperspectral data in coastal waters

The impact of the microphysical properties of aerosol on the atmospheric correction of hyperspectral data in coastal waters

Improved Accuracy of Chlorophyll-a Concentration Estimates from MODIS Imagery Using a Two-Band Ratio Algorithm and Geostatistics: As Applied to the Monitoring of Eutrophication Processes over Tien Yen Bay (Northern Vietnam)

Estimating total alkalinity for coastal ocean acidification monitoring at regional to continental scales in Australian coastal waters

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