## Abstract

A radiative transfer model was applied to examine the effects of vertically stratified inherent optical properties of the water column associated with near-surface plumes of suspended particulate matter on spectral remote-sensing reflectance, ${R}_{\mathrm{rs}}(\lambda )$, of coastal marine environments. The simulations for nonuniform ocean consisting of two layers with different concentrations of suspended particulate matter (SPM) are compared with simulations for a reference homogeneous ocean whose SPM is identical to the surface SPM of the two-layer cases. The near-surface plumes of particles are shown to exert significant influence on ${R}_{\mathrm{rs}}(\lambda )$. The sensitivity of ${R}_{\mathrm{rs}}(\lambda )$ to vertical profile of SPM is dependent on the optical beam attenuation coefficient within the top layer, ${c}_{1}(\lambda )$, thickness of the top layer, ${z}_{1}$, and the ratio of SPM in the underlying layer to that in the top layer, ${\mathrm{SPM}}_{2}/{\mathrm{SPM}}_{1}$, as well as the wavelength of light, $\lambda $. We defined a dimensionless spectral parameter, $P(\lambda )={c}_{1}(\lambda )\times {z}_{1}\times ({\mathrm{SPM}}_{2}/{\mathrm{SPM}}_{1})$, to quantify and examine the effects of these characteristics of the two-layer profile of SPM on the magnitude and spectral shape of ${R}_{\mathrm{rs}}(\lambda )$. In general, the difference of ${R}_{\mathrm{rs}}(\lambda )$ between the two-layer and uniform ocean decreases to zero with an increase in $P(\lambda )$. For the interpretation of ocean color measurements of water column influenced by near-surface plumes of particles, another dimensionless parameter ${P}^{\prime}(\lambda )$ was introduced, which is a product of terms representing homogenous ocean and a change caused by the two-layer structure of SPM. Based on the analysis of this parameter, we found that for the two-layer ocean there is a good relationship between ${R}_{\mathrm{rs}}(\lambda )$ in the red and near-infrared spectral regions and the parameters describing the $\mathrm{SPM}(z)$ profile, i.e., ${\mathrm{SPM}}_{1}$, ${\mathrm{SPM}}_{2}$, and ${z}_{1}$.

© 2013 Optical Society of America

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