An Empirical Method to Derive Ocean Waves From Second-Order Bragg Scattering
- Prospects and Limitations
K.-W. GURGEL, H. H. ESSEN, and T. SCHLICK
IEEE Oceanic Engineering, VOL. 31, NO. 4, October 2006, pp. 804...811.
Abstract - -
High-frequency (HF) radar wave processing is often based on the inversion of the Barrick-Weber
equations, introduced in 1977. This theory reaches it's limitations if the
length of the Bragg-scattering wave raises to the order of the significant
waveheight, because some assumptions are no longer met. In this case, the only
solution is to move to lower radar frequencies, which is not possible or
desirable in all cases. This paper describes work on an empirical solution which
intends to overcome this limitation.
However, during high sea state the first-order Bragg peaks sometimes could
not be clearly identified which avoids the access to the second-order
These cases cause problems to the algorithm which have not been solved yet
and currently limit the maximum significant waveheight to about the same values
as reported for the integral inversion method.
The regression parameters of the empirical solution calibrated from the
European Radar Ocean Sensing
(EuroROSE) dataset are constant values for the complete experiment and
when applied to the HF radar data they reconstruct the measurements by
a colocated wave buoy quite well. When including a radar frequency
dependent scaling factor to the regression parameters, the new algorithm
can also be used at different radar frequencies.
The second-order frequency bands used for the empirical
solution are sometimes disturbed by radio interference and ship echoes.
Investigations are presented to identify and solve these situations.
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