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International Journal of Geophysics
Volume 2012, Article ID 459497, 11 pages
http://dx.doi.org/10.1155/2012/459497
Research Article

Long-Term Temporal Variability of the Freshwater Discharge and Water Levels at Patos Lagoon, Rio Grande do Sul, Brazil

1Laboratory of Physical, Coastal and Estuarine Oceanography, Institute of Oceanography, Federal University of Rio Grande, P.O. Box 474, 96200-900 Rio Grande, RS, Brazil
2Institute of Mathematics, Statistics and Physics, Federal University of Rio Grande, P.O. Box 474, 96200-900 Rio Grande, RS, Brazil

Received 5 January 2012; Revised 4 April 2012; Accepted 22 April 2012

Academic Editor: Zdenek Martinec

Copyright © 2012 G. P. Barros and W. C. Marques. This is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.

Abstract

The aim of this study is to investigate the importance of freshwater discharge as a physical forcing in Patos Lagoon at timescales longer than one year, as well as identify the temporal variability of the dominant processes in freshwater discharge and water levels along the Patos Lagoon. Due to its proximity to the mouth, the water level at the estuary is influenced by the remote effects associated with the adjacent ocean circulation and wave climatology, reducing the observed correlation. At the lagoonar region a high correlation is expected because interannual data is being used, reducing the influence of the wind. Cross wavelet technique is applied to examine the coherence and phase between interannual time-series (South Oscillation Index, freshwater discharge and water levels). The freshwater discharge of the main tributaries and water levels in Patos Lagoon are influenced by ENSO on interannual scales (cycles between 3.8 and 6 years). Therefore, El Niño events are associated with high mean values of freshwater discharge and water levels above the mean. On the other hand, La Niña events are associated with low mean values of freshwater discharge and water levels below the mean.