Optical scattering properties of phytoplankton: Measurements and comparison of various species at scattering angles between 1° and 170°

We describe the results of a laboratory scattering experiment performed to investigate differences in the optical scattering properties between five common phytoplankton species (Dunaliella tertiolecta, Isochrysis galbana, Nanochloropsis, Skeletonema costatum, and Thalassiosira weissflogii). Data sets were taken at scattering angles 1° to 170° at incident polarizations parallel and perpendicular to the scattering plane. Differences between the species were especially apparent in the slopes at near-forward (1°-10°) angles and the enhanced scattering at near-backward (150°-165°) angles. There were also notable differences observed between the depolarization ratios, especially at scattering angles between 70° and 110°. The data are shown to be not only helpful in differentiating several species from each other, but also in separating the phytoplankton from bubble/hydrosol contributions to the ocean's inherent optical properties. The results presented here motivate the development of in situ large-angle polarimetric scatterometers and associated retrieval algorithms.