Biological Interpretation of Ocean Color:
Observations and Models for Waters of the Mid-Atlantic Shelf

Principal Investigator:   Heidi M. Sosik
Sponsoring Agency:  National Aeronautics & Space Administration

Understanding the magnitude and distribution of marine phytoplankton biomass and production is a fundamental problem in biological oceanography which may be solved in part through interpretation of satellite-based ocean color.  The research project aims to contribute to improved methods for interpretation of ocean color through a multidisciplinary, collaborative research effort using several sampling platforms including research ships, oceanographic moorings and satellites.  We have taken advantage of a field experiment on the mid-Atlantic continental shelf, which is part of the Office of Naval Research's Coastal Mixing and Optics (CMO) Accelerated Research Initiative.  This collaborative effort between optical and physical oceanographers represents an unique opportunity to gain fundamental insights into the sources of variability in surface ocean reflectance and its relationship to phytoplankton pigment concentration and the rate of primary production.
Our work, aimed at improved interpretation of SeaWiFS data, includes the application of some recent advances in optical tools and the development of approaches for incorporating information from moorings to estimate primary production.  We are exploring relationships between ocean reflectance and variability in the distributions of particle optical properties; his is being accomplished through use of shipboard laser-based flow cytometry and both in situ and remote determinations of ocean color.  Plans for combining mooring- and satellite-based measurements to obtain accurate estimates of seasonal primary production on the mid-Atlantic shelf originally includes addition of a Fast Repetition Rate (FRR) fluorometer to the CMO optical mooring, but delays in instrument production precluded this.  Current work includes evaluation of the FRR instruments capability to provide quantitative information about phytoplankton optical and photosynthetic properties which can not be assessed based on passive remote sensing, but which are critical determinants of the rate of production.  Future plans include the mooring of the FRR on Georges Bank.

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