Passive ocean color remote sensing has revolutionized our ability to quantify horizontal patterns of algal distributions across the ocean surface. However, models based on passive ocean color alone often fail to predict integrated water column primary productivity accurately in coastal environments, primarily because they lack specific knowledge of vertical distribution of phytoplankton. LIDAR (Light Detection And Ranging), an active remote sensing tool, offers to provide critical insights into the vertical distribution of plankton throughout the water column, significantly improving our ability to model biogeochemical processes in the upper ocean, particularly in coastal waters where significant biomass often resides below the first optical depth and provides 70 to 80% of the total euphotic zone integrated production. We developed a simple 2-flow radiative transfer model of LIDAR propagation through an optically active water column that can be inverted to retrieve the vertical distribution of inherent and apparent optical properties, and the distribution of particles throughout the euphotic zone. Model predictions have been validated by laboratory and field observations, and serve as the basis for significantly improving remotely sensed primary productivity estimates for the coastal ocean. We are now constructing a ship-based LIDAR system to further explore the capability of this technology to provide rapid and accurate information on the vertical distribution of particles in the coastal ocean, and their material properties (biological vs. mineral, photosynthetic vs. non-photosynthetic, etc.) that can significantly enhance our understanding of ocean biogeochemistry.

Dr. Zimmerman's research interests focus on the ecophysiology of marine photosynthesis, radiative transfer in natural waters and the use of remote sensing technology to understand biogeochemical processes of the ocean. He received B.S., M.S., and Ph.D. degrees in Biology from the University of Southern California. He then spent several years as a Research Scientist at Hopkins Marine Station and Moss Landing Marine Laboratories. He moved to Old Dominion University in 2003, where he is currently Department Chair and Professor of Ocean, Earth and Atmospheric Sciences.

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