Sensors 2008, 8(8), 4611-4635; doi:10.3390/s8084611
Article

HF Radar Sea-echo from Shallow Water

Received: 4 June 2008; in revised form: 21 July 2008 / Accepted: 23 July 2008 / Published: 6 August 2008
(This article belongs to the Special Issue Ocean Remote Sensing)
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: HF radar systems are widely and routinely used for the measurement of ocean surface currents and waves. Analysis methods presently in use are based on the assumption of infinite water depth, and may therefore be inadequate close to shore where the radar echo is strongest. In this paper, we treat the situation when the radar echo is returned from ocean waves that interact with the ocean floor. Simulations are described which demonstrate the effect of shallow water on radar sea-echo. These are used to investigate limits on the existing theory and to define water depths at which shallow-water effects become significant. The second-order spectral energy increases relative to the first-order as the water depth decreases, resulting in spectral saturation when the waveheight exceeds a limit defined by the radar transmit frequency. This effect is particularly marked for lower radar transmit frequencies. The saturation limit on waveheight is less for shallow water. Shallow water affects second-order spectra (which gives wave information) far more than first-order (which gives information on current velocities), the latter being significantly affected only for the lowest radar transmit frequencies for extremely shallow water. We describe analysis of radar echo from shallow water measured by a Rutgers University HF radar system to give ocean wave spectral estimates. Radar-derived wave height, period and direction are compared with simultaneous shallow-water in-situ measurements.
Keywords: HF radar oceanography; wave measurement; remote sensing.
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MDPI and ACS Style

Lipa, B.; Nyden, B.; Barrick, D.; Kohut, J. HF Radar Sea-echo from Shallow Water. Sensors 2008, 8, 4611-4635.

AMA Style

Lipa B, Nyden B, Barrick D, Kohut J. HF Radar Sea-echo from Shallow Water. Sensors. 2008; 8(8):4611-4635.

Chicago/Turabian Style

Lipa, Belinda; Nyden, Bruce; Barrick, Don; Kohut, Josh. 2008. "HF Radar Sea-echo from Shallow Water." Sensors 8, no. 8: 4611-4635.

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