CoAuthors

Jesus Gómez-Enri (Department of Applied Physics. Universidad de Cádiz, Spain); Martin Saraceno (CIMA/CONICET-UBA, Argentina)

The La Plata River Estuary is located in the eastern coast of South America at approximately 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 23000 m3/sec. Previous studies have shown that the estuarine circulation is vulnerable to the river run-off and wind variability. In particular, changes in wind seem to be the main forcing of the river circulation, especially at sub-annual scales. The objective of this work is to analyze the descending pass #0964 and ascending pass # 0493 of ENVISAT RA2 (18 Hz) in this region. We evaluate the performance of each correction applied to the altimetry data. Results show that both passes are sensible to the different retrackings. ICE1 recover more data in the proximity of the coast in pass #0493 and pass #0964. We applied a criterion to remove outliers (-/+2 standard deviation) keeping the nominal position along the track with less that 20% of missing values in both passes. As a result, correlation coefficients between altimetry data and a tide gauge deployed in the study area are 0.61 (95%CL) and 0.87 (95%CL) for pass #0493 and #0964, respectively when no tide and atmospheric corrections are considered. We also analyze the dynamic atmospheric correction obtained with a global barotropic model (MOG2D: Modèle aux Ondes de Gravitè 2-Dimensions) and two regional barotropic models (HamSOM: Hamburg Shelf Ocean Model, SMARA). Results show that the global model underestimates the variability of the sea level response to pressure and wind forcing in comparison with the regional models. The ENVISAT RA2 data will be corrected by the atmospheric effect with the best model. Then we will examine the capabilities of the altimetry data to measure the sea level variability due to freshwater discharges from the main tributaries of Río de la Plata.