A 3-LAYERED SPHERE MODEL OF THE OPTICAL-PROPERTIES OF PHYTOPLANKTON

Theoretical scattering computations are performed on a phytoplankton model consisting of three concentric spheres. The outer sphere represents the wall, membrane, or frustule and is assigned a relatively high index of refraction with no absorption. The middle layer represents the chloroplasts and is assigned a relatively low index of refraction with absorption. The core represents the balance of the cytoplasm and is given a low index of refraction with no absorption. The model is applied to an observed size distribution from the Pacific central gyre. This model produced significantly more backscattering and attenuation than a low-index, homogeneous-sphere model. Changing the distribution of cell-wall thickness as a function of particle size produces much variation in the shape of the volume scattering function.