Evaluation of the applicability of a global satellite turbidity algorithm in turbid waters with high content of phytoplankton using numerical simulations and field data
March 4, 2022
Licenciatura en Ciencias Físicas (2022). Departamento de Física Juan José Giambiagi, Facultad de Ciencias Exactas y Naturales, Universidad de Buenos Aires. Directores: Dra. A. I. Dogliotti y Dr. J.I. Gossn
The decline in the quality of coastal, estuarine and inland waters has become a worrying global problem as anthropogenic activities expand and climate change threatens to cause major alterations in the hydrological cycle. This decrease is manifested in alterations in the biological, physical and chemical characteristics of natural water, which makes it essential to monitor water quality indicators such as turbidity, the concentration of particulate matter and chlorophyll-a (used as an estimator of the phytoplankton biomass). Monitoring these variables directly is slow and costly, so the use of new technologies to observe these systems remotely is essential. In this sense, remote sensing in the optical region of the electromagnetic spectrum (or ocean color) allows obtaining information on the optical and biogeochemical properties – such as turbidity and the concentration of suspended particulate matter – of the surface layer of the water from the spectral and amplitude variation of the reflectance coming from the water. In this work, an evaluation of the limitations of a satellite turbidity algorithm that uses the red and infrared bands of the spectrum was carried out using simulations and field data of optically complex waters such as those of the Río de la Plata. In particular, the objective of the work was to simulate hyperspectral water reflectance and integrated in the spectral bands of a set of satellite systems in operation and in development, the analysis of the sensitivity of the turbidity algorithm and the evaluation of the spectral features. The results showed the correct operation of the turbidity algorithm in the near infrared range, as well as its limitations when using the red part of the electromagnetic spectrum for the calculation of this variable in the particular case of water with a high chlorophyll-a content.
