Rip Current Observations via Marine Radar
Publication: Journal of Waterway, Port, Coastal, and Ocean Engineering
Volume 140, Issue 2
Abstract
New remote sensing observations that demonstrate the presence of rip current plumes in X-band radar images are presented. The observations collected on the Outer Banks (Duck, North Carolina) show a regular sequence of low-tide, low-energy, morphologically driven rip currents over a 10-day period. The remote sensing data were corroborated by in situ current measurements that showed depth-averaged rip current velocities were whereas significant wave heights were . Somewhat surprisingly, these low-energy rips have a surface signature that sometimes extends several surf zone widths from shore and persists for periods of several hours, which is in contrast with recent rip current observations obtained with Lagrangian drifters. These remote sensing observations provide a more synoptic picture of the rip current flow field and allow the identification of several rip events that were not captured by the in situ sensors and times of alongshore deflection of the rip flow outside the surf zone. These data also contain a rip outbreak event where four separate rips were imaged over a 1-km stretch of coast. For potential comparisons of the rip current signature across other radar platforms, an example of a simply calibrated radar image is also given. Finally, in situ observations of the vertical structure of the rip current flow are given, and a threshold offshore wind stress () is found to preclude the rip current imaging.
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Acknowledgments
We thank Kent Hathaway, Jesse McNinch, Jeff Hanson, and the staff at the Field Research Facility, Field Data Collections and Analysis Branch, U.S. Army Corps of Engineers for providing the in situ data and for their overall support during field activities. This work was funded through Office of Naval Research (ONR) Grant No. N00014-10-1-0932. P. Catalan was partially funded by ONR Global Grant No. N62909-10-1-4061 and Comisión Nacional de Investigación Científica y Tecnológica de Chile (CONICYT) Grant Nos. FONDECYT-1120878 and FONDAP-15110017 and Basal Project FB0821.
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Published In
Journal of Waterway, Port, Coastal, and Ocean Engineering
Volume 140 • Issue 2 • March 2014
Pages: 115 - 124
Copyright
© 2014 American Society of Civil Engineers.
History
Received: Dec 19, 2012
Accepted: Jul 27, 2013
Published online: Jul 30, 2013
Published in print: Mar 1, 2014
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