Absorption, Scattering, and Remote-Sensing Reflectance Relationships in Coastal Waters: Testing aNew Inversion Algorithm
Keywords:Remote sensing, reflectance, optics, absorption coefficient, scattering coefficient, ocean optics, coastal remote sensing.
AbstractIn-water absorption and scattering coefficients, and above-water remote-sensing reflectance are tightly linked and, in coastal waters, exhibit unique spectral characteristics at near-infrared wavelengths. The surface-reflectance is uncoupled from the total, measured reflectance, the corrected remote sensing reflectance is calculated by difference, then the absorption and scattering coefficients are estimated using a new inversion algorithm. The surface correction and inversion algorithms are based on a reflectance difference at 715-735 nm. At these wavelengths, total absorption is due primarily to pure water absorption, and the reflected sky/cloud light and backscattering spectra are nearly flat. Required algorithm parameters, and ultimately the corrected remote sensing reflectance spectra and spectral absorption and scattering estimates, can be refined if in situ measurements of absorption at 412 nm and spectral scattering shape are available. The coupled surface correction/inversion algorithms were tested using data from 14 experiments at five U.S. coastal locations collected over a three-year period and representing a variety of absorption and scattering regimes. The average errors between measured and modeled absorption and scattering coefficients over the 400-700 nm wavelength range were 14.6% and 3.0%, respectively (without regard to sign).