Quantum Yields of Soluble Particulate Material in the Ocean

Our goal is to develop a more detailed understanding of the role of fluorescence as a source of trans-spectral energy in the underwater light field and the biological and chemical causes for variations in the spectral source terms. We will (1) determine the spectral quantum yield of cDOM and photosynthetic pigments; (2) assess the impact of steady state growth conditions on phytoplankton pigment in vivo quantum yields; (3) run model sensitivity analyses to determine the importance of transspectral sources in defining the submarine light field; and (iv) assess the implications of trans-spectral sources for hyperspectral remote sensors. The proposed work is significant for the ONR optics program because no systematic, quantitative evaluation of the trans-spectral source terms have been accomplished and the quantum yields of the different components, which are essential for modeling and prediction, are poorly specified. The work is also of importance for the biology/chemistry programs since, despite the ubiquitous use of fluorescence as a tool to study cDOM and phytoplankton, the fundamental understanding of the processes in terms of quantum fluxes is not well known. We anticipate that our work will enhance the ability to predict optical, chemical and biological processes in the ocean. Our goal is to study the quantum yields of fluorescence of various components including dissolved, detrital particulate and phytoplankton. We will assess the role of fluorescence of these various components to contribute trans-spectral sources within the water column and environmental conditions that govern the fluorescence of biological and chemical components. Combining laboratory work and radiative transfer modeling, we will define which sources must be accounted for to understand the intensity of irradiance in the ocean for sources other than the natural solar flux and Raman.