Evaluation of a potential operational test site for Sentinel-2 products validation in Chascomús, a shallow turbid lake in the Argentinean Pampa Plain.

DOGLIOTTI, ANA; SÁNCHEZ, MARÍA LAURA; GOSSN, JUAN IGNACIO; ZAGARESE, HORACIO

Frascati

Workshop; Sentinel-2 Validation Team Meeting; 2018

Sentinel-2 Validation Team

In a satellite mission the validation of derived products is essential to assess and ensure high-quality geophysical data products. The MultiSpectral Instrument (MSI) on board of Sentinel-2 mission provides high spatial resolution data which can be relevant for monitoring coastal and in-land waters. With similar characteristics, the Operational Land Imager (OLI) sensor on board of Landsat 8 has been demonstrated to provide high-quality aquatic products over coastal and inland waters, even though it was a mission originally designed for land applications, like Sentinel-2. Moreover, the MSI sensor in comparison with OLI offers higher spatial resolution (10 and 20 m compared to 30 m) and additional spectral bands in the near infrared (NIR) and a red-edge band at 705 nm, advantageous for retrieving total suspended matter and chlorophyll-a concentration in optically complex coastal waters. In the context of mission validation efforts, a new network of hyperspectral radiometers is being developed for radiometric validation of satellite missions in the frame of HYPERMAQ and HYPERNETS (H2020) projects. Within these projects, a fixed station site has been proposed as a test site for validation of satellite missions like Sentinel-2 in Chascomús Lake in the Pampa Plain in the Buenos Aires Province (Argentina). The Chascomús lake, with a surface of 28.7 km2 and a mean depth of 1.53 m, belongs to a system of seven shallow lakes arranged as chained water bodies located in one of the most productive regions for agriculture and livestock breeding of Argentina. It is an eutrophic, turbid, shallow water body which is permanently mixed and which transparency is mainly controlled by suspended particles where both phytoplankton and non-pigmented particles contribute in a similar way to total absorption. This lake has been intensively studied in the last 20 years and is subject to field campaigns within existing projects. As a possible validation site, Chascomús lake is here characterized in terms of the temporal and spatial variability of optical properties based on information from Sentinel-2 high spatial resolution sensor. A qualitative validation analysis of remote sensing reflectance (Rrs) and water constituents products, like Turbidity is here presented in the preparation of a validation site for hyperspectral data in the frame of the mentioned projects. The quality of the products is evaluated by comparisons with OLI-derived products and compared to the expected natural variability. Time series of products like Turbidity from S2A & B and OLI showed consistency between the missions, however the quality of Rrs and derived products require further validation to ensure performance, which is the main objective of setting this validation site.