Contribution of Chlorophyll Fluorescence to the Reflectance Spectra in Coastal Waters and its Application to Retrieval Algorithms

Sam Ahmed, Optical Remote Sensing Laboratory, The City University of New York/NASA URC, ahmed@ccny.cuny.edu (Presenting)
Alexander Gilerson, Optical Remote Sensing Laboratory, The City University of New York/NASA URC, gilerson@ee.ccny.cuny.edu (Presenting)
Jing Zhou, Optical Remote Sensing Laboratory, The City University of New York/NASA URC, jzhou@ccny.cuny.edu
Ioannis Ioannou, Optical Remote Sensing Laboratory, The City University of New York/NASA URC, yannismail@gmail.com
Soe Hlaing, Optical Remote Sensing Laboratory, The City University of New York/NASA URC, soeminhlaing@gmail.com
Barry Gross, Optical Remote Sensing Laboratory, The City University of New York/NASA URC, gross@ccny.cuny.edu
Fred Moshary, Optical Remote Sensing Laboratory, The City University of New York/NASA URC, moshary@ccny.cuny.edu

We parameterized the Chl fluorescence component of the reflectance spectra for coastal waters as a function of [Chl], CDOM and mineral concentrations based on findings from both simulations and field measurements. In this model, variations in fluorescence magnitude are attributed primarily to the variability of in absorption/scattering of water components, rather than to variations in the Chl fluorescence quantum yield, which, to be in conformity with results of observations and simulations, appears to be relatively stable at about 1 % and at about 0.5% if the cell reabsorption coefficient is taken into account. The scope of these results is generalized by extensive Hydrolight simulations and field data from other authors and our campaign in the Chesapeake Bay which included measurements of hyper-spectral reflectance, in water absorption and attenuation (AC-S, WET Labs) and sampling and extraction of [Chl] and TSS organic and inorganic mass components. They were used to analyze impacts of specific chlorophyll absorption spectra, illumination and viewing conditions, etc, on fluorescence magnitudes in coastal waters. It is shown that the fluorescence magnitude does not depend substantially on the viewing angle in the range of angles from -60 to 60 degrees. Fluorescence height (FLH) algorithm performance for MODIS, MERIS were also studied for various conditions to evaluate the utility of incorporating model relationships developed showing that correlation between [Chl] and FLH exists only for [Chl] < 5-10 ug/l.