Ocean Surface Features Observed by HF Coastal Ground-Wave Radars: A Progress Review
High Frequency (HF) coastal radar systems measure and employ the Doppler spectrum of the sea-echo signal to extract relevant ocean surface parameters. The dominant first-order spectral peaks provide mean surface currents; at medium frequencies (MF) they have been used to yield directional information about the wave height spectrum. The second-order spectral continuum is related to the wave height directional spectrum through a nonlinear integral equation. This integral equation has been inverted for narrow-beam coastal radars having large antennas to demonstrate the validity of the theoretical model upon which inversion techniques are based.
The present paper reviews progress which has been made to date in the determination of ocean current and wave conditions from HF radar sea echo. The results have associated statistical variance due to finite sampling of a random distribution of wave heights. A 200-sample average allows the amplitude spectrum and the directional distribution of wind-driven waves to be determined within confidence limits of 10%. The corresponding accuracy of ocean current determination is about 20 cm/s.
KeywordsWave Height Ocean Wave Directional Factor Doppler Spectrum Radar Beam
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