Ocean surface radar current measurements in the surf break zone at Coffs Harbour

Heron, Mal, and Prytz, Arnstein (2003) Ocean surface radar current measurements in the surf break zone at Coffs Harbour. In: Proceedings of the Coasts and Ports Australiasian Conference 2003. pp. 1-8. From: Coasts and Ports Australiasian Conference 2003, 9-12 September 2003, Auckland, New Zealand.

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Ocean surface radars are being used routinely to map surface currents over tens of kilometres at resolutions typically around 3 km. At higher frequencies, in the VHF band, the Bragg wavelength for backscatter is reduced so that at 152.2 MHz the dominant scatter is from a wave with a wavelength just shorter than 1 m, compared with 5 m at 30 MHz. At this wavelength, the Bragg waves are heavily modulated by underlying wind waves and swell which produce significant broadening of the first-order Bragg peaks. The broadening of the peaks does not significantly impair our ability to locate the frequency of the peak and hence to derive surface current measurements. An upward-looking acoustic current profiler was used for inter-comparison with the surface currents measured by the radar. The deployment at Coffs Harbour was relatively short, but included calm conditions as well as a period of strong winds where the breaker zone extended well out from the shore. Although both the acoustic current meter measurements and the radar surface current data were affected by the presence of swell, it is clear that the VHF radar has potential to monitor rip currents and coastal vortices under surf break conditions when conventional techniques become limited.

Item ID: 3543
Item Type: Conference Item (Research - E1)
ISBN: 0-473-09832-6
Keywords: ocean surface radar; surface currents; surf, rip currents, swell
Date Deposited: 20 Jul 2009 01:52
SEO Codes: 96 ENVIRONMENT > 9699 Other Environment > 969902 Marine Oceanic Processes (excl. Climate Related) @ 100%
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