Internal Solitary Waves in the Brazilian SE Continental Shelf : Observations by Synthetic Aperture Radar

We present an analysis of internal solitary waves (ISWs) on the SE Brazilian continental shelf using a set of Envisat/ASAR satellite images. For the 17-month observation period, 467 ISW packets were detected. Most of observed solitons were associated to 4–6 ms-1 wind. The number of ISW packets shows...

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Bibliographic Details
Published in:International Journal of Oceanography 2013-01, Vol.2013 (2013), p.1-11
Main Authors: Lorenzzetti, João A., Dias, Fabian G.
Format: Article
Language:English
Subjects:
Brazil
Breaking
Continental shelves
Marine
Shelves
Solitary waves
Solitons
Summer
Tides
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Summary:We present an analysis of internal solitary waves (ISWs) on the SE Brazilian continental shelf using a set of Envisat/ASAR satellite images. For the 17-month observation period, 467 ISW packets were detected. Most of observed solitons were associated to 4–6 ms-1 wind. The number of ISW packets shows a seasonal signal with a peak in summer, with higher concentration in the outer shelf in all seasons, followed by midshelf during the summer. Propagation direction of ISWs was predominantly onshore with packets separated by typical M2 internal tide wavelengths (~10–40 km). The highest values of the barotropic tidal forcing F are concentrated at the shelf break between 200 and 500 m isobaths. These characteristics suggest that ISWs are formed from nonlinear disintegration of internal tides generated at the shelf break that propagate shoreward as interfacial internal waves. No significant change in the number of ISWs from spring to neap tides was observed in spite of significant tidal current variation (60%). Even not being a region of strong tides, this study shows that ISWs are a frequent and widespread feature, possibly playing a significant dynamic role, affecting biological production, sediment dispersion, and transport.
ISSN:1687-9406
1687-9414
DOI:10.1155/2013/403259