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

DOGLIOTTI, A.I.; ZAGARESE, H. E.; SANCHEZ, M. L.; GOSSN, J.I

Frascati

Encuentro; Sentinel-2 Validation Team Meeting; 2018

In a satellite mission the validation of derived products is essential toassess and ensure high-quality geophysical data products. The MultiSpectralInstrument (MSI) on board of Sentinel-2 mission provides high spatialresolution data which can be relevant for monitoring coastal and in-landwaters. With similar characteristics, the Operational Land Imager (OLI) sensoron board of Landsat 8 has been demonstrated to provide high-quality aquaticproducts over coastal and inland waters, even though it was a missionoriginally designed for land applications, like Sentinel-2. Moreover, the MSIsensor in comparison with OLI offers higher spatial resolution (10 and 20 mcompared to 30 m) and additional spectral bands in the near infrared (NIR) anda red-edge band at 705 nm, advantageous for retrieving total suspended matterand chlorophyll-a concentration in optically complex coastal waters. In the contextof mission validation efforts, a new network of hyperspectral radiometers isbeing developed for radiometric validation of satellite missions in the frameof HYPERMAQ and HYPERNETS (H2020) projects. Within these projects, a fixedstation site has been proposed as a test site for validation of satellitemissions like Sentinel-2 in Chascomús Lake in the Pampa Plain in the Buenos Aires Province (Argentina). TheChascomús lake, with a surface of 28.7 km2 and a mean depth of 1.53m, belongs to a system of seven shallow lakes arranged as chained water bodies locatedin one of the most productive regions for agriculture and livestock breeding ofArgentina. It is an eutrophic, turbid, shallow water body which is permanentlymixed and which transparency is mainly controlled by suspended particles where bothphytoplankton and non-pigmented particles contribute in a similar way to totalabsorption. This lake has been intensively studied in the last 20 years and issubject to field campaigns within existing projects. As a possible validation site,Chascomús lake is here characterized in terms of the temporal and spatialvariability of optical properties based on information from Sentinel-2 high spatialresolution sensor. A qualitative validation analysis of remote sensingreflectance (Rrs) and water constituent products, like Turbidity ishere presented in the preparation of a validation site for hyperspectral datain the frame of the mentioned projects. The quality of the products isevaluated by comparisons with OLI-derived products and compared to the expectednatural variability. Time series of products like Turbidity from S2A & Band L8-OLI showed consistency between the missions, however the quality of Rrsand derived products require further validation to ensure performance, which isthe main objective of setting this validation site.