Phytoplankton and the optical properties of surface waters

For decades, oceanographers have used optical measurements such as ocean color and chlorophyll fluorescence to describe the distributions of phytoplankton on scales from millimeters to ocean basins, with great success. And all along, researchers who study the biology of phytoplankton have shown that the fundamental processes that determine variability in these optical measurements - absorption of light by phytoplankton and its emission as chlorophyll fluorescence - can be strongly influenced by photosynthetic physiology, species composition and cell size. Optical observation of the ocean therefore has the potential to go "beyond biomass" toward synoptic, continuous and depth-resolved assessment of the physiological status and community structure of phytoplankton from measurements that are integral to ocean observing systems. In turn, it is recognized by some that these same measurements can be used to guide a next generation of physical, ecological and biogeochemical models that are directly constrained by optical observations describing the fundamental processes of light absorption and its utilization in photosynthesis, as well as the scattering of light by particles.My goal is to contribute significantly to this transformational change in interdisciplinary oceanography and marine prediction. The research proposed here will integrate insights from the literature describing more than 50 years of oceanographic and physiological research with the most modern approaches to observation and modeling. The objectives of the proposed research include quantitative and critical testing of existing and new bio-optical models, and the development and evaluation of next-generation approaches to interdisciplinary modeling. This will be achieved through analysis of data from ocean observing systems (including ocean gliders, moored sensor arrays and ocean color satellites) and experimental assessments of chlorophyll fluorescence under a range of environmental conditions. The hallmarks of the proposed program of research - and importantly, training - are sound foundations in 20th century oceanography and a firm commitment to advancing the leading edge of interdisciplinary ocean science in the 21st.