Light Scattering Properties and Processes of Coastal Waters

Abstract

Abstract : Characterizing the volume scattering function (VSF) of oceanic waters remains one of the most outstanding problems in optical oceanography. The goal of this program is to significantly advance our knowledge of the VSF of oceanic waters, particularly coastal waters. To achieve this goal we are developing new VSF instruments that are capable of accurately and routinely measuring in situ profiles of the complete VSF. Once we have developed the necessary tools for measuring the complete VSF, our long-term goal is to use these tools to quantitatively characterize and model the light scattering properties and processes of oceanic waters. Our scientific objective is to measure, in situ, the volume scattering function concomitant with other optical property measurements and the particle size distribution in a wide variety of oceanic waters. Since we already have at hand a number of instruments and methods for measuring the absorption, beam attenuation, and backward-scattering coefficients [Maffione and Dana, 1997; Dana et al., 1998], the VSF measurement will provide the only missing link to definitively testing instrument closure. By means of closure we will be able to quantitatively document the accuracy of our optical property measurements. A related objective is to investigate the accuracy of using Mie theory to compute the VSF based on the particle size distribution [Jackson et al., 1997] and index of refraction. In general we will apply our VSF measurements to a wide variety of modeling problems in optical oceanography. Our technological objective is to develop accurate, in-situ profiling instruments that can measure the VSF over the range of scattering angles from 0.1 to 170 degrees.