An empirical algorithm to estimate spectral average cosine of underwater light field from remote sensing data in coastal oceanic waters

Abstract

The underwater average cosine is an apparent optical property of water that describes the angular distribution of radiance at a given point in water. Here, we present a simple empirical algorithm to estimate spectral underwater average cosine (λ) where the wavelength λ ranges from 400 nm to 700 nm, based only on the apparent optical property, remote sensing reflectance, R rs (λ), and solar zenith angle. The algorithm has been developed using the measured optical parameters from the coastal waters off Goa, India, and eastern Arabian Sea and the optical parameters derived using the radiative transfer code using these measured data. The algorithm was compared with two earlier reported empirical algorithms of Haltrin (1998Haltrin ( , 2000, and the performance of the algorithm was found to be better than these two empirical algorithms. The algorithm is based on single optical parameter; remote sensing reflectance, which can be easily measured in-situ, and is available from the ocean color satellite sensors; hence this algorithm will find applications in the ocean color remote sensing.

Land use and land cover change based on historical space–time model

“…Remote sensing can observe and monitor rapidly changing systems, for instance, land-sea-atmosphere energy exchange, ocean current, atmospheric ozone, as well as system changing in a slow way (Ferreira et al, 2015;Amuti and Luo, 2014). Ahmad et al (2010) studied soil water content using remote sensing data; Talaulikar et al (2014) estimated the average cosine value of an underwater light field in the ocean using remote sensing data. By using spectral angle mapping (SAM) and multi-source information innovatively, this study analyzes land use and land cover in the Qiantang River based on a historical space-time model, aiming to provide a powerful information support for the optimization of land use structure in the Qiantang River in Zhejiang and the reasonable allocation of land resource and a new approach for research analysis.…”