Measuring large river freshwater discharge in Rio de la Plata (South America) estuary using in-situ and coastal altimetry data

GOMEZ-ENRI, J.; RUIZ ETCHEVERRY, L.A.; SARACENO, M.

Constance

Workshop; 8th Coastal Altimetry Workshop; 2014

In this work we analyze the capabilities of a dual-frequency radar altimetry (RA-2) instrument to measure the sea level oscillations due to large freshwater discharges from the main tributaries to Río de la Plata estuary in South America. The Río de la Plata Estuary is located in the eastern coast of South America at proximately 35ºS. This extensive and shallow region is one of the largest estuaries of the world. The estuary is formed by the confluence of the Paraná and Uruguay rivers that generate a mean discharge of about 22000 m3/seg. The ESA ENVISAT mission was launched in March 2002 with a dual-frequency radar altimetry (RA-2). The satellite was operative until the end of the mission in May 2012. The Geophysical Data Record (GDR) product gives along-track geophysical parameters: Sea Surface Height, Significant Wave Height and Wind Speed at sea level at 1 Hz posting rate (with an along-track distance of about 7 km). The Sensor Geophysical Data Record (SGDR) product, instead, give along-track data (altitude and range) at 18 Hz posting rate (about 350 m). Thus, it is possible to retrieve geophysical information at a better along-track spatial resolution respect to the GDR official product. In addition, RA-2 waveforms are retracked on-ground with four retrackers simultaneously: Ice-1, Ice-2, Sea-Ice and Brown. Time series of 18 Hz sea level altimeter data were created from the outputs of the four retrackers available in the SGDR product. Coastal altimeter products will be validated against sea level ground truth from a tide gauge deployed in the study area. Altimeter data were obtained from two RA-2 passes: descending #0960 and ascending #0493.