Measurement Of Ocean Wave Spectra Using Narrow-beam HF Radar

Howell, R.; Walsh, J.

doi:10.1109/igarss.1989.575977

Cited by 29 publications

(28 citation statements)

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“…Therefore, the significant waveheight can be derived from the integral of the secondorder echo spectra. In the following years, Lipa et al [8] , Wyatt [9] , Howell et al [10] , Hisaki [11] and Green et al [12] proposed several methods to obtain directional wave spectrum through the inversion of Barrick's second-order nonlinear equation. All methods would provide more comprehensive information on directional wave spectrum.…”

Section: Introductionmentioning

confidence: 99%

Experimental determination of significant waveheight by OSMAR071: Comparison with results from buoy

Shao

et al. 2009

Wuhan Univ. J. Nat. Sci.

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OSMAR071 is the latest product of the OSMAR (ocean state monitor and analysis radar) series of high frequency surface wave radar (HFSWR), which was developed by the Radiowave Propagation Laboratory of Wuhan University. It adopts a modified Barrick waveheight inversion model. The modifications are introduced to improve the model's performances under the effect of noises and interferences and in the case of broad beam radar detection. The two unknown coefficients in the modified model are figured out by fitting the HFSWR significant waveheight results to those output from a wave buoy located in the radiating coverage of the radar site. The model is applied to inverse the waveheights from radar data for the duration from Dec. 1st, 2008 to Feb. 25th, 2009, and then the radar waveheights are compared with the buoy measurements. Results show that the rms difference between radar-derived significant waveheights and those from the buoy is 0.38 m and the correlation coefficient between the two series is 0.66. This study describes OSMAR071 observation of significant waveheight with relatively satisfactory accuracy during about three months.High frequency surface wave radar (HFSWR) operated in the HF band (3-30 MHz), as the name suggests, employs the ground wave mode of radio wave propagation, in which the radar signal is guided by a good conducting surface such as the ocean surface to follow a path that essentially matches the earth's curvature. It is capable of all-weather remote sensing of large-area ocean surface dynamics with relatively high precision [1] . After more than 40 years' development, its capability of current detection has been considered to satisfy the requirements for routine marine observations while its wind and wave outputs have not reached the matched status [2] . Currents information can be extracted from the broadening of the Bragg peaks (which are also called as the first-order peaks) in the sea echoes' Doppler spectra. The second-order continuum which contain the information of waves and winds is relatively weak (20-40 dB lower than the Bragg peaks) and susceptible to the effect of noise and interference, so the extraction of waves and winds information is difficult [3] and the corresponding inversion theory and technology are still currently under development. Much progress has been made to understand the relationship between the Doppler spectrum of the radar backscatter signals and the ocean wave spectrum [4] . In 1977 Barrick proposed an inversion model of significant waveheight [5] , which can work robustiously in practice [6,7] . It is different from several other algorithms, which relate the inversion of wave spectra to the second-order sea echoes directly. Therefore, the significant

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Section: Introductionmentioning

confidence: 99%

Experimental determination of significant waveheight by OSMAR071: Comparison with results from buoy

Shao

et al. 2009

Wuhan Univ. J. Nat. Sci.

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“…The basic mechanisms behind the application of HFSWR for surface current measurements are that (1) the Bragg frequencies of resonant waves are altered by the underlying surface currents, (2) the Doppler shifts are directly related to the relative velocities and inversely proportional to the radar wavelength, and (3) the resonant waves and underlying surface currents are linearly superimposed (Stewart and Joy 1974;Barrick et al 1977;Howell and Walsh 1993). Based on these mechanisms, many HFSWR systems are developed for mapping surface currents, such as CODAR (Barrick and Evans 1979) and WERA (Gurgel et al 1999).…”

Section: Introductionmentioning

confidence: 99%

Remote sensing of surface currents with single shipborne high-frequency surface wave radar

Wang

Xie

et al. 2015

Ocean Dynamics

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High-frequency surface wave radar (HFSWR) is a useful technology for remote sensing of surface currents. It usually requires two (or more) stations spaced apart to create a twodimensional (2D) current vector field. However, this method can only obtain the measurements within the overlapping coverage, which wastes most of the data from only one radar observation. Furthermore, it increases observation's costs significantly. To reduce the number of required radars and increase the ocean area that can be measured, this paper proposes an economical methodology for remote sensing of the 2D surface current vector field using single shipborne HFSWR. The methodology contains two parts: (1) a real space-time multiple signal classification (MUSIC) based on sparse representation and unitary transformation techniques is developed for measuring the radial currents from the spreading first-order spectra, and (2) the stream function method is introduced to obtain the 2D surface current vector field. Some important conclusions are drawn, and simulations are included to validate the correctness of them.

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“…Barrick (1972) derived expressions that relate the first-and second-order returns to the ocean surface wave energy spectra. Methods to invert the Barrick (1972) equations and retrieve the surface wave directional energy spectrum have been developed by Lipa (1978), Lipa and Barrick (1986), Wyatt (1990), Howell and Walsh (1993) and Hisaki (1996). Wyatt et al (1999) demonstrated that when using two radar sites, inversion methods can yield reliable wave directional spectral estimates comparable to those recorded by moored buoys.…”

Section: A Hf Radar Wave Observationsmentioning

confidence: 99%

Wind Speed Dependence of Single-Site Wave-Height Retrievals from High-Frequency Radars

Haus

Shay

Work

et al. 2010

Journal of Atmospheric and Oceanic Technology

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Wave-height observations derived from single-site high-frequency (HF) radar backscattered Doppler spectra are generally recognized to be less accurate than overlapping radar techniques but can provide significantly larger sampling regions. The larger available wave-sampling region may have important implications for observing system design. Comparison of HF radar-derived wave heights with acoustic Doppler profiler and buoy data revealed that the scale separation between the Bragg scattering waves and the peak energy-containing waves may contribute to errors in the single-site estimates in light-to-moderate winds. A wave-height correction factor was developed that explicitly considers this scale separation and eliminates the trend of increasing errors with increasing wind speed.

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Measurement Of Ocean Wave Spectra Using Narrow-beam HF Radar

Cited by 29 publications

References 1 publication

Experimental determination of significant waveheight by OSMAR071: Comparison with results from buoy

Experimental determination of significant waveheight by OSMAR071: Comparison with results from buoy

Remote sensing of surface currents with single shipborne high-frequency surface wave radar

Wind Speed Dependence of Single-Site Wave-Height Retrievals from High-Frequency Radars

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