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Particle size distributions (8-105qm diameter), chlorophyll a, and particulate carbon were measured off the Oregon coast during July 1973. The particle counts were transformed to volume concentration and then subjected to characteristic vector analysis. Ninety-two percent of the variance was accounted for by linear combinations of the first two characteristic vectors. Two weighting factors define the proportions of the two characteristic vectors which will, when added to the mean volume concentration curve, approximate the actual data for each sample. Variations in the first weighting factor correspond well with variations in total volume.Changes in the second weighting factor indicate which segment of the size range contains the largest proportion of the particulate volume. Comparison with temperature and salinity data indicated that the near surface water with proportionately large volumes of particles less than 20 ,um was warmer and less saline than the surface waters with large volumes between 20 and 50 ,um. High correlation with particulate carbon and chlorophyll suggests that in both cases a large proportion of the particles is phytoplankton. During

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Intermediate nepheloid layers were observed by a beam transmissometer operating at 650 nm during 3 -8 November 1976 over the continental shelf and slope off Oregon.Two well defined intermediate nepheloid layers were observed. One was located at about 150 m depth and extended westward from a point 10 NM offshore.The second was at about 375 m depth and went westward from a point 25 NM offshore.They were at least 15 NM wide (east --west dimension), and 50 -150 m thick.They closely followed isotherms in the zonal section. The overall structure of the nepheloid layers remained unchanged during the period of the cruise.The intermediate nepheloid layers appear to have been generated by lateral diffusion and advection of turbid water from bottom nepheloid layers over the continental shelf and slope toward the deep water.Possible processes of diffusion and advection of bottom nepheloid layers to generate intermediate nepheloid layers are discussed.

It is shown that the complex index of refraction of a given particle-size distribution may be calculated if the particle extinction coefficient and the particle absorption coefficient are known. If the particles are assumed to be nonabsorbing, a real index of refraction may be calculated from the ratio of light scattering at 45' from the forward for two wavelengths. Application of the method to two stations off Ecuador indicates that the particle index of refraction can be determined with sufficient accuracy to become an important parameter in the study of the oceans.

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