Influences of absorption and scattering on vertical changes in the average cosine of the underwat... more Influences of absorption and scattering on vertical changes in the average cosine of the underwater light field
Limnol. Oceanogr., 34(5), 1989, 868-881 ?) 1989, by the American Society of Limnology and Oceanog... more Limnol. Oceanogr., 34(5), 1989, 868-881 ?) 1989, by the American Society of Limnology and Oceanography, Inc. Natural fluorescence of chlorophyll a: Relationship to photosynthesis and chlorophyll concentration in the ... DA Kiefer and WS Chamberlin Department of ...
: Our objective is to conduct a comprehensive study of the optical properties of marine microorga... more : Our objective is to conduct a comprehensive study of the optical properties of marine microorganisms and other biogenic particles in order to determine their optical cross-sections and contribution to absorption and scattering by sea water. Our major effort during the last year was aimed at quantifying diel changes in scattering and absorption cross-sections of phytoplankton cells. This study is related to our hypothesis that the relatively large diel cycle in the beam attenuation coefficient that has been observed in the ocean is in part caused by diel change in the size and refractive index of cells comprising the phytoplankton community. Another effort was focused on testing the applicability of the dynamic light scattering (DLS) technique for characterizing the size distribution of small marine particles (< 5 microns) including the submicron range. While we previously used this technique for studying the cultures of heterotrophic marine bacteria, this time we focus our atte...
Abstract As part of a project examining climate change in the Southern California Bight at the Un... more Abstract As part of a project examining climate change in the Southern California Bight at the University of Southern California, we studied the linkage of the variability of sea surface temperature across three nested spatial scales, the north Pacific Basin, the West Coast of North American, and the Southern California Bight. Specifically, we analyzed daily GHRSST images between September 1981 and July 2009. In order to remove seasonal changes in temperature and focus upon differences between years, we calculate weekly mean ...
Our research over the last 5 years indicates that the successful transformation of ocean color im... more Our research over the last 5 years indicates that the successful transformation of ocean color imagery into maps of bio-optical properties will require continued development and testing of algorithms. In particular improvements in the accuracy of predicting from ocean color imagery the concentration of the bio-optical components of sea as well as the rate of photosynthesis will require progress in at least three areas: (1) we must improve mathematical models of the growth and physiological acclimation of phytoplankton; (2) we must better understand the sources of variability in the absorption and backscattering properties of phytoplankton and associated microparticles; and (3) we must better understand how the radiance distribution just below the sea surface varies as a function sun and sky conditions and inherent optical properties.
Much of the optical variability in the upper sea is caused by variations in the biogenous micropa... more Much of the optical variability in the upper sea is caused by variations in the biogenous microparticles, which include the phytoplankton, the Chroococoid cyanobaccteria, and detritus. It is instructive to consider two sources of variability in these biogenous particles. First, changes in the absorption cross section of individual cells result from responses of phytoplankton to the ambient nutrient and light fields. These responses are relatively rapid (days) and a mathematical description of the response is presented. Second,changes in the concentration of detrital particles and cells are more difficult to predict and occur on time scales of weeks. A crude hypothetical model is presented which attempts to describe the general response of the plantonic community to light and nutrient fields.
Deep Sea Research Part A. Oceanographic Research Papers, 1988
Methods are described for the measurement of spectral absorption coefficients, fluorescence excit... more Methods are described for the measurement of spectral absorption coefficients, fluorescence excitation, and fluorescence yields for pigmented particles retained on filters. The corrections required for absorption coefficients include determining increased optical pathlength while corrections for fluorescence include determining system spectral variability, mean light level and reabsorption. The empirical technique is consistent with and validated by theoretical relationships for light transmission and fluorescence of absorbing particulate material embedded in a medium with intense scattering.These methods were applied to a study of photoadaptation in several phytoplankton species and revealed variations in the blue for chlorophyll α specific absorption [αph*(λ)] and fluorescence excitation [F*(λ)] of greater than 3− and 10-fold, respectively. Variations in the spectral shapes and the magnitude of αph*(λ) and F*(λ) with photoadaptation are determined largely by the effect of pigment absorption in discrete particles, sometimes referred to as the sieve or package effect. A model is presented expressing F*(λ) in terms of α*(λ) which predicts large variability in F*(λ) due to cell size and cellular pigmentation and which may help reconcile the previously reported, but unexplained variations in F*(λ). Spectral variations in the fluorescence yield appear to be caused by variations in the fraction of light absorbed by photosystem II which fluoresces as compared to photosystem I or photoprotective pigments which do not fluoresce. The techniques presented provide a rapid, reproducible, and simple approach for routine analysis, particularly for field applications where particle densities are too low for direct analysis of absorption spectra.
Influences of absorption and scattering on vertical changes in the average cosine of the underwat... more Influences of absorption and scattering on vertical changes in the average cosine of the underwater light field
Limnol. Oceanogr., 34(5), 1989, 868-881 ?) 1989, by the American Society of Limnology and Oceanog... more Limnol. Oceanogr., 34(5), 1989, 868-881 ?) 1989, by the American Society of Limnology and Oceanography, Inc. Natural fluorescence of chlorophyll a: Relationship to photosynthesis and chlorophyll concentration in the ... DA Kiefer and WS Chamberlin Department of ...
: Our objective is to conduct a comprehensive study of the optical properties of marine microorga... more : Our objective is to conduct a comprehensive study of the optical properties of marine microorganisms and other biogenic particles in order to determine their optical cross-sections and contribution to absorption and scattering by sea water. Our major effort during the last year was aimed at quantifying diel changes in scattering and absorption cross-sections of phytoplankton cells. This study is related to our hypothesis that the relatively large diel cycle in the beam attenuation coefficient that has been observed in the ocean is in part caused by diel change in the size and refractive index of cells comprising the phytoplankton community. Another effort was focused on testing the applicability of the dynamic light scattering (DLS) technique for characterizing the size distribution of small marine particles (< 5 microns) including the submicron range. While we previously used this technique for studying the cultures of heterotrophic marine bacteria, this time we focus our atte...
Abstract As part of a project examining climate change in the Southern California Bight at the Un... more Abstract As part of a project examining climate change in the Southern California Bight at the University of Southern California, we studied the linkage of the variability of sea surface temperature across three nested spatial scales, the north Pacific Basin, the West Coast of North American, and the Southern California Bight. Specifically, we analyzed daily GHRSST images between September 1981 and July 2009. In order to remove seasonal changes in temperature and focus upon differences between years, we calculate weekly mean ...
Our research over the last 5 years indicates that the successful transformation of ocean color im... more Our research over the last 5 years indicates that the successful transformation of ocean color imagery into maps of bio-optical properties will require continued development and testing of algorithms. In particular improvements in the accuracy of predicting from ocean color imagery the concentration of the bio-optical components of sea as well as the rate of photosynthesis will require progress in at least three areas: (1) we must improve mathematical models of the growth and physiological acclimation of phytoplankton; (2) we must better understand the sources of variability in the absorption and backscattering properties of phytoplankton and associated microparticles; and (3) we must better understand how the radiance distribution just below the sea surface varies as a function sun and sky conditions and inherent optical properties.
Much of the optical variability in the upper sea is caused by variations in the biogenous micropa... more Much of the optical variability in the upper sea is caused by variations in the biogenous microparticles, which include the phytoplankton, the Chroococoid cyanobaccteria, and detritus. It is instructive to consider two sources of variability in these biogenous particles. First, changes in the absorption cross section of individual cells result from responses of phytoplankton to the ambient nutrient and light fields. These responses are relatively rapid (days) and a mathematical description of the response is presented. Second,changes in the concentration of detrital particles and cells are more difficult to predict and occur on time scales of weeks. A crude hypothetical model is presented which attempts to describe the general response of the plantonic community to light and nutrient fields.
Deep Sea Research Part A. Oceanographic Research Papers, 1988
Methods are described for the measurement of spectral absorption coefficients, fluorescence excit... more Methods are described for the measurement of spectral absorption coefficients, fluorescence excitation, and fluorescence yields for pigmented particles retained on filters. The corrections required for absorption coefficients include determining increased optical pathlength while corrections for fluorescence include determining system spectral variability, mean light level and reabsorption. The empirical technique is consistent with and validated by theoretical relationships for light transmission and fluorescence of absorbing particulate material embedded in a medium with intense scattering.These methods were applied to a study of photoadaptation in several phytoplankton species and revealed variations in the blue for chlorophyll α specific absorption [αph*(λ)] and fluorescence excitation [F*(λ)] of greater than 3− and 10-fold, respectively. Variations in the spectral shapes and the magnitude of αph*(λ) and F*(λ) with photoadaptation are determined largely by the effect of pigment absorption in discrete particles, sometimes referred to as the sieve or package effect. A model is presented expressing F*(λ) in terms of α*(λ) which predicts large variability in F*(λ) due to cell size and cellular pigmentation and which may help reconcile the previously reported, but unexplained variations in F*(λ). Spectral variations in the fluorescence yield appear to be caused by variations in the fraction of light absorbed by photosystem II which fluoresces as compared to photosystem I or photoprotective pigments which do not fluoresce. The techniques presented provide a rapid, reproducible, and simple approach for routine analysis, particularly for field applications where particle densities are too low for direct analysis of absorption spectra.
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