Ocean Color Inversion Research Articles

Spectral variability of the particulate backscattering ratio

The spectral dependency of the particulate backscattering ratio is relevant in the fields of ocean color inversion, light field modeling, and inferring particle properties from optical measurements. Aside from theoretical predictions for spherical, homogeneous particles, we have very limited knowledge of the actual in situ spectral variability of the particulate backscattering ratio. This work presents results from five research cruises that were conducted over a three-year period. Water column profiles of physical and optical properties were conducted across diverse aquatic environments that offered a wide range of particle populations. The main objective of this research was to examine the behavior of the spectral particulate backscattering ratio in situ, both in terms of its absolute magnitude and its variability across visible wavelengths, using over nine thousand 1-meter binned data points for each of five wavelengths of the spectral particulate backscattering ratio. Our analysis reveals no spectral dependence of the particulate backscattering ratio within our measurement certainty, and a geometric mean value of 0.013 for this dataset. This is lower than the commonly used value of 0.0183 from Petzold's integrated volume scattering data. Within the first optical depth of the water column, the mean particulate backscattering ratio was 0.010.

Spectral beam attenuation coefficient retrieved from ocean color inversion

A reflectance inversion model in presented in which particle backscattering is parameterized by the particle backscattering ratio, attenuation and absorption coefficients rather than a hyperbolic function. This parameterization removes backscattering spectral constraints and yields independent estimates of the magnitude and spectral slope of the particle beam attenuation, which have been found to correlate with the particle concentration and size distribution, respectively. The model yields estimates of component absorption and backscattering consistent with observations and Mie models, particularly for environments dominated by phytoplankton and other strongly absorbing particles.