Jrv. Zaneveld et Jc. Kitchen, THE VARIATION IN THE INHERENT OPTICAL-PROPERTIES OF PHYTOPLANKTON NEAR AN ABSORPTION PEAK AS DETERMINED BY VARIOUS MODELS OF CELL STRUCTURE, J GEO RES-O, 100(C7), 1995, pp. 13309-13320
Optical oceanography models of attenuation and scattering properties o
ften contain simple spectral relationships. Electromagnetic theory, ho
wever, predicts fluctuations in the spectra of the attenuation coeffic
ients and scattering properties of substances at wavelengths near an a
bsorption peak. We have modeled these effects for phytoplankton using
homogeneous, two-layered, and three-layered sphere models of cell stru
cture and using a wide range of plausible particle size distributions.
The magnitude of the scattering in backward directions is affected th
e most. The effect on the beam attenuation spectra is relatively small
compared with the effect on the absorption and scattering coefficient
s. The backscattering coefficient shows large variability, varying by
almost a factor of 3 for some models. The results suggest that beam at
tenuation at any wavelength in the red shorter than the wavelength of
the chlorophyll absorption peak will be insensitive to the chlorophyll
content of the particles. Increases in the pigment content per unit v
olume of phytoplankton will increase the index of refraction in the in
frared and therefore increase the attenuation and scattering coefficie
nts there.