We present an experimental model of CDOM solar-stimulated fluorescence. Three-dimensional fluorescence spectra of natural waters were use to determine the solar-stimulated emission as a function of depth in the water column. Inclusion of the wavelength-dependent fluorescence quantum yield provides emission values in absolute units of photons s^-1 cm^-2 5nm^-1. Attenuation of light in the water column was also modeled, allowing determination of total upwelled emission. The upwelled fluorescence is compared to irradiance reflectance calculated from a semianalytical model. The fluorescence contribution to reflectance in the blue-green region can be as high as 70% for blackwater, but is rapidly reduced by the introduction of scattering particles. Except for blackwaters. CDOM fluorescence does not significantly affect irradiance reflectance ratios commonly used in remote-sensing applications. In water with moderate amounts of CDOM (absorption coefficient at 355 nm >/= 0.5 m^-1), fluorescence will dominate water Raman scattering as a secondary influence on the light field in the green spectral region.
Department, Program, or Center
Chester F. Carlson Center for Imaging Science (COS)
Limnology and Oceanography 39N1 (1994) 1-11
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