Optical Signatures of Particle Size and Dynamics in the Marine Environment

Particulate matter in the ocean is ubiquitous, ranging in size from submicron colloids to large marine snow aggregates. Particle size and dynamics play major roles in-and are reflective of -many marine processes, ranging from ocean-basin scale phytoplankton blooms to sediment transport in coastal regions. The use of optical sensing techniques such as remote sensing or in situ scattering sensors affords ex-amination of these dynamics across comparable, relevant, process scales. How the optical properties, especially backscattering, are dependent on the size, composition, and packaging of particulate matter remains an active area of research, using both modeling and empirical approaches. This dissertation advances new methods for making measurements of particle optical properties in the environment, and uses these methods for examining how the optical properties of particles depend on their size distribution and packaging into aggregates. Advances in methodology include the adaptation of an existing instrument for measurement of near-forward scattering, providing some of the first measurements of this important property in decades. The near-forward scattering is also related to particle dynamics in the bottom boundary layer. A method for measurement of optical properties that is resistant to bio-fouling is also described, and used over several years to build a dataset of particle size distribution and multi-spectral optical properties. The spectral shape of attenuated and backscattered light is shown to be related to the particulate size distribution in the highly-scattering bottom boundary layer. Finally, since a variety of dynamic processes act to change the particle size distribution in the environment, two experiments are described to isolate the effects of particle aggregation in order to link changes in particle packaging to optical properties