Retrieval of particle scattering coefficients and concentrations by genetic algorithms in stratified lake water

Abstract

We retrieved the mass-specific scattering coefficient b*sm(λ) = 0.60·(λ/650)-1.82 of the inhomogeneous and optically complex water column of eastern Lake Constance in May 2012. In-situ measured and modelled remote-sensing reflectance Rrs(λ) were matched via a parameter search procedure using genetic algorithms. The optical modelling consisted of solving the azimuthally-averaged Radiative Transfer Equation, forced with in-situ suspended matter concentration (sm) data. b*sm(λ) was univocally determined at red wavelengths. In contrast, we encountered unresolved spectral ambiguity at blue wavelengths due to the absence of organic absorption in our dataset. Despite this, a surprisingly good sm retrieval regression is achieved (R2 > 0.95 with respect to independent data) using our b*sm(λ). Acquisition of accurate inherent optical properties in future field campaigns is needed to verify the estimated b*sm(λ) and related assumptions.