The use of high spectral resolution in situ optical data for monitoring case II (coastal) water quality
The use of high spectral resolution in situ optical data for monitoring case II (coastal) water quality
Data were collected in optically diverse waters in the Baltic Sea, the N.W. Atlantic ocean, the Mediterranean Sea and in the River Hamble, UK. Spectral signatures similar to those of phytoplankton pigments, coloured dissolved organic matter (gelbstoff) and inorganic sediments were observed in reflectances from the Mediterranean, Baltic and Southampton Water respectively. New spectral values of the downwelling diffuse attenuation coefficient, Kd(λ), are presented, corresponding to mean euphotic zone depths at 550nm ranging between 5m in the Baltic and >80m in the Mediterranean.
Algorithms based on reflectance ratios for retrieving chlorophyll-a concentrations were tested for a variety of wavelength bands used in existing or historical satellite sensors. Narrow bands (±5nm or less) located as for the German sensor MOS and the American sensor MoDIS were found to perform best for the range of waters studied. Reflectance ratios for 443:615 or 530:665 gave the best correlations with chlorophyll-a for a dataset from Baltic and Atlantic waters (r2=0.7, n=70), and significant correlations between absorption by gelbstoff and ratios 443:530 were found.
The fourth derivative of reflectance spectra showed that particular spectral features appeared consistently in data from optically diverse waters. The reflectance data were used to calculate absorption spectra using a simple reflectance model and these spectra were deconvolved into a series of Gaussian bands. Multiple regressions between band heights and pigments resulted in significant correlations with several taxonomic marker pigments. Absorption by gelbstoff was found to be well correlated with a Gaussian band centred in the near UV. These results indicate that in situ or above water measurements of reflectance, at sufficiently high spectral resolution, may be used to monitor phytoplankton succession patterns as well as gelbstoff.
University of Southampton
Schwarz, Jill N
51edce73-7ada-4eda-9cfc-8ff6bb4f83f5
2001
Schwarz, Jill N
51edce73-7ada-4eda-9cfc-8ff6bb4f83f5
Schwarz, Jill N
(2001)
The use of high spectral resolution in situ optical data for monitoring case II (coastal) water quality.
University of Southampton, Doctoral Thesis.
Record type:
Thesis
(Doctoral)
Abstract
Data were collected in optically diverse waters in the Baltic Sea, the N.W. Atlantic ocean, the Mediterranean Sea and in the River Hamble, UK. Spectral signatures similar to those of phytoplankton pigments, coloured dissolved organic matter (gelbstoff) and inorganic sediments were observed in reflectances from the Mediterranean, Baltic and Southampton Water respectively. New spectral values of the downwelling diffuse attenuation coefficient, Kd(λ), are presented, corresponding to mean euphotic zone depths at 550nm ranging between 5m in the Baltic and >80m in the Mediterranean.
Algorithms based on reflectance ratios for retrieving chlorophyll-a concentrations were tested for a variety of wavelength bands used in existing or historical satellite sensors. Narrow bands (±5nm or less) located as for the German sensor MOS and the American sensor MoDIS were found to perform best for the range of waters studied. Reflectance ratios for 443:615 or 530:665 gave the best correlations with chlorophyll-a for a dataset from Baltic and Atlantic waters (r2=0.7, n=70), and significant correlations between absorption by gelbstoff and ratios 443:530 were found.
The fourth derivative of reflectance spectra showed that particular spectral features appeared consistently in data from optically diverse waters. The reflectance data were used to calculate absorption spectra using a simple reflectance model and these spectra were deconvolved into a series of Gaussian bands. Multiple regressions between band heights and pigments resulted in significant correlations with several taxonomic marker pigments. Absorption by gelbstoff was found to be well correlated with a Gaussian band centred in the near UV. These results indicate that in situ or above water measurements of reflectance, at sufficiently high spectral resolution, may be used to monitor phytoplankton succession patterns as well as gelbstoff.
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Published date: 2001
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Local EPrints ID: 464380
URI: http://eprints.soton.ac.uk/id/eprint/464380
PURE UUID: 7c561ce2-781e-435c-b00a-df734e3e3168
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Date deposited: 04 Jul 2022 22:22
Last modified: 16 Mar 2024 19:28
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Author:
Jill N Schwarz
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