PUBLICACIONES

Charla invitada. International Ocean Color Science Meeting 2017. 15-18 May, 2017, Lisbon, Portugal.

Retrieving information from ocean colour radiometry in very turbid waters is highly challenging. In particular the Río de la Plata (RdP) river, the widest river in the world located in the eastern coast of South America at approximately 35 °S, carries high amounts of suspended particulate which are mainly provided by the Bermejo River, considered amongst the most turbid rivers in the world. Very high concentrations of suspended particulate matter (SPM) have been reported ranging from 100 to 300 g m^-3 and extreme concentrations of around 1,000 g m^-3. Interest in retrieving water constituents using remote sensing is mainly motivated by the environmental and economic importance of this estuary, specially for the countries on its shores, Argentina and Uruguay.

One of the first work performed using remote sensing data in the turbid waters of RdP was a qualitatively evaluation of atmospheric correction algorithm. However, at that time a direct validation of satellite-derived estimates could not be performed due to lack of in situ reflectance measurements. After experiences gained in different renown institutions and in collaboration with the Argentine National Space Agency and the University of Buenos Aires, field campaigns have been performed and the first bio-optical data has been collected in this region allowing a first evaluation of atmospheric correction algorithms. Since then, strong efforts have been put in collecting field measurements and in acquiring new instruments to improve our knowledge of this complex and interesting system. Given the high amount of suspended particulate matter that the RdP exports to the adjacent shelf waters, directly affecting phytoplankton productivity, nutrient dynamics and transport of pollutants, the focus has been put in retrieving SPM and in particular turbidity, an optical property more related to reflectance than SPM. A general algorithm to retrieve turbidity from ocean color data has been proposed and used to analyze 15 years of MODIS-derived turbidity maps. The seasonal and inter-annual variability of turbidity and its relation with Oceanic Nino Index (ONI) and the water discharge of RdP tributaries were assessed.

Given the high amount of sediments the availability of light is significantly reduced being not the ideal condition for phytoplankton to grow, however intense blooms have been detected in the estuary, like Microcystis sp. blooms in November 2012 in Buenos Aires and in February 2015 in Montevideo coasts. However, retrieving chlorophyll concentration in very turbid waters is highly challenging.

More recently, at the beginning of 2016, the city of Buenos Aires suffered a large invasion of floating aquatic Hyacinths (Eichhornia crassipes) which could be observed by different ocean colour sensors and for which a floating vegetation index adapted for turbid waters has been developed and applied to detect and quantify them.

This presentation draws mainly on experiences gathered throughout the early and present stage of my research in these extreme and optically complex waters which have been possible thanks to the support of different institutions and successful collaborations with researchers from different parts of the world.