Nature of optical products inverted semianalytically from remote sensing reflectance of stratified waters

Abstract

Analytical expressions between inherent optical properties (IOPs) retrieved using semi‐analytical algorithms (SAAs) and the vertical distributions of IOPs are derived based on an analytical model for subsurface remote sensing reflectance (rrs). These expressions provide a theoretical and comprehensive understanding of the inverted IOPs for stratified waters and lay the foundation to obtain equivalent products from profiling measurements for apple‐to‐apple comparison of the remotely sensed properties. It is found that the backscattering coefficient (bb) derived from an rrs spectrum via an SAA is governed by rrs in the longer wavelengths, consequently the inverted bb has less (or negligible) contributions from deeper depths, such as the subsurface chlorophyll maximum. In addition, the inverted bb spectrum does not have the spectral feature of the vertically weighted average bb. The SAA‐derived absorption coefficients, on the other hand, are found related to both the weighting profile at the wavelength of interest and the weighting profile in the longer wavelength(s). As a result, the absorption coefficients in the shorter wavelengths inverted from a perfect SAA are generally lower (can be 40% or more) than its vertically weighted average unless the surface layer dominates the diffuse attenuation of light. Furthermore, unlike the historical perception of remotely sensed chlorophyll concentration (Chl) for stratified waters, SAA‐derived Chl is also sensitive to the vertical profile of bb and tends to be lower than its vertically weighted average assuming perfect bio‐optical relationships, unless surface properties dominate the water column.

Associations between spectral properties, bacteriological characteristics, chlorophyll and zooplankton communities in two north Patagonian lakes

“…The use of remote-sensing techniques has been widely applied for water quality studies (Dar et al, 2020;De los Ríos-Escalante et al, 2020;Freire da Silva et al, 2020;Jones et al, 2020;Lee et al, 2020;Martins et al, 2020;Naumenko, 2020;Topp et al, 2020), and specifically for associations between water colour and spectral properties (Chander et al, 2020;Shen et al, 2020). In this scenario, Drozd et al (2020), Kwon et al (2020) andSòria-Perpinyà et al (2020), proposed the use of remote-sensing techniques and the relations between photosynthetic pigments in a temporal and spatial gradient in lakes.…”

Ciências Biológicas e da Saúde: Investigação e Prática II

“…El uso de técnicas de percepción remota en lagos ha tenido mucha importancia en las últimas décadas, pues sobre la base de la resolución de los sensores de las fotografías satelitales y el uso de técnicas computacionales y de ciencias de datos es posible lograr conseguir parámetros ambientales como temperatura, y pigmentos fitoplanctónicos (Chandler et al, 2020;Dar et al, 2020;Kwon et al, 2020;Lee et al, 2020;Shen et al, 2020;Soria et al, 2020). Estos estudios pueden servir de base para manejo de contaminación por exceso de nutrientes con la consecuente eutroficación en lagos (Chandler et al, 2020;Lee et al, 2020).…”

Inherent optical properties of dissolved and particulate matter in an Arctic fjord (Storfjorden, Svalbard) in early summer

“…Despite their limited availability, field observations thus remain the main source of information regarding IOPs in the Arctic. They also constitute a unique way of capturing the complex vertical structure of the optical properties in Arctic waters, the knowledge of which is essential for the remote sensing of stratified waters (Lee et al, 2020). In addition, increasing the number of observations through new surveys is critical for strengthening the statistical characterization of the parameters used when building regional bio-optical models (Kostakis et al, 2020), both for calibration and validation of ocean colour satellite products (Orkney et al, 2020) and for getting an accurate representation of optical properties in numerical models.…”