Poster Session 1, Monday, October 3, 15:40–18:00
Optical Sediment Trap: Scattering Properties of Accumulating Sinking Marine Particles
The biological carbon pump consists of processes that transfer organic carbon into the ocean interior: the gravitational sinking of particulate detritus from the biologically-productive surface into deep waters; the activities of animals capable of moving large vertical distances in the ocean; the physical motions of seawater. We are working to develop an “optical sediment trap” (OST) sensor for autonomous profiling floats, that will measure the gravitational flux carrying the greatest amount of biological carbon into the deep ocean. The optical sediment trap works by illuminating an optical window and measuring the increasing light attenuation by particles that have settled on the window over time while the float drifts for several days at depth between profiles. A key question underlaying the OST concept is how the forward scattering by accumulated, sinking particles is affected by the physical and biogeochemical properties of the particles. Since there is not an easily employed, existing model for angularly-resolved forward scattering by a concentrated layer of complex, non-spherical aggregates, we use an empirical approach to characterize the optical scattering properties of particles accumulating on the OST collection surface. We will present initial results from a lab experiment measuring forward scattering function as well as beam and diffuse attenuations as relevant to design of the OST.
Margaret Estapa, University of Maine, School of Marine Sciences, Darling Marine Center, [email protected], 0000-0002-8000-8517
Sean O’Neill, University of Maine, School of Marine Sciences, Darling Marine Center, [email protected]