Wave height and wind direction from the HF coastal ocean surface radar

Heron, M.L.; Prytz, A.

doi:10.5589/m02-031

Cited by 33 publications

(12 citation statements)

References 10 publications

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“…Barrick et al 1974) or wave height (cf. Heron and Prytz 2002). Gurgel et al (2006) provided an empirical method to estimate the ocean wave spectrum from the second-order sidebands, that is extended to the directional spectrum when information from two stations are available.…”

Section: Wind Speed and Direction Estimation From Hf Radarsmentioning

confidence: 99%

Wind-speed inversion from HF radar first-order backscatter signal

et al. 2011

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Land-based high-frequency (HF) radars have the unique capability of continuously monitoring ocean surface environments at ranges up to 200 km off the coast. They provide reliable data on ocean surface currents and under slightly stricter conditions can also give information on ocean waves. Although extraction of wind direction is possible, estimation of wind speed poses a challenge. Existing methods estimate wind speed indirectly from the radar derived ocean wave spectrum, which is estimated from the second-order sidebands of the radar Doppler spectrum. The latter is extracted at shorter ranges compared with the first-order signal, thus limiting the method to short distances. Given this limitation, we explore the possibility of deriving wind speed from radar first-order backscatter signal. Two new methods are developed and presented that explore the relationship between wind speed and wave generation at the Bragg frequency matching that of the radar. One of the methods utilizes the absolute energy level of the radar first-order peaks while the second method uses the directional spreading of the wind generated waves at the Bragg frequency. For both methods, artificial neural network analysis is performed to derive the interdependence of the relevant parameters with wind speed. The first method is suitable for application only at single locations where in situ data are available and the network has been trained for while the second method can also be used outside of the training location on any point within the radar coverage area. Both methods require two or more radar sites and information on the radio beam direction. The methods are verified with data collected in Fedje, Norway, and the Ligurian Sea, Italy using beam forming HF WEllen RAdar (WERA) systems operated at 27.68 and 12.5 MHz, respectively. The results show that application of either method requires wind speeds above a minimum value (lower limit). This limit is radar frequency dependent and is 2.5 and 4.0 m/s for 27.68 and 12.5 MHz, respectively. In addition, an upper limit is identified which is caused by wave energy saturation at the Bragg wave frequency. Estimation of this limit took place through an evaluation of a year long database of ocean spectra generated by a numerical model (third generation WAM). It was found to be at 9.0 and 11.0 m/s for 27.68 and 12.5 MHz, respectively. Above this saturation limit, conventional second-order methods have to be applied, which at this range of wind speed no longer suffer from low signal-to-noise ratios. For use in operational systems, a hybrid of first- and second-order methods is recommended

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Section: Wind Speed and Direction Estimation From Hf Radarsmentioning

confidence: 99%

Wind-speed inversion from HF radar first-order backscatter signal

et al. 2011

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“…If one assumes that a system consists of two radar sites in order to produce surface current maps, then at each point on the sea surface there are two determinations of first-order ratio and, theoretically (with no noise) there is a closed solution for the dominant direction of the Bragg waves. For waves with wavelength 10-20m this represents the wind direction except only in conditions of rapid wind shifts, when a settling time of about half an hour has to be considered [7]. People are having reasonable success with the determination of wind direction from dual radar systems, although from an operational point of view there is still a need to validate the product in the local setting.…”

Section: Surface Currentsmentioning

confidence: 98%

HF Ocean Surface Radar Monitoring for Coral Bleaching in the Great Barrier Reef

Heron

Willis

Prytz³

et al. 2006

Oceans 2006

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HF ocean surface radar provides a valuable multiparameter monitoring technique for the investigation and management of coral bleaching. The physical parameters normally associated with bleaching are temperature and light, which are primarily controlled by insolation, wind, waves and currents. The radar provides a useful monitoring of wind and waves, and is the leading technology for monitoring surface currents. The deployment of an HF radar in the Great Barrier Reef at the Heron Island study area provides ideal infrastructure for the study of the physical processes which affect coral bleaching and the spread of coral disease.

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“…However, acquisition of these parameters in the fleld presents a signiflcant challenge due to the variability and hostility of the coastal environment. A variety of methods have previously been used to extract wave height information including in situ instrimientation such as wave buoys, pressure transducers or manometers (i.e., Grace, 1978), wave staffs, and capacitance and resistance probes (Whittenbury, Huber, and Newell, 1959) and shore-based remote techniques such as visual estimation or measurement (BahsUie and Carter, 1984;Patterson and Blair, 1983), highfrequency (HF) radar (Heron and Prytz, 2002;Wyatt, 1988), and single and stereo camera imagery (e.g., Bechle and Wu, 2011;de Vries eiaZ., 2010;Hilmer, 2005;Mitchell, 1983;Sasaki, Horikawa, and Hotta, 1976).…”

Section: Introductionmentioning

confidence: 99%

Automated Detection of Breaking Wave Height Using an Optical Technique

Shand

Bailey

Shand

2011

Journal of Coastal Research

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I www.JCRonline.org SHAND, T.D.; BAILEY, D.G., and SHAND, R.D., 2012. Automated detection of breaking wave height using an optical technique. Journal of Coastal Research, 28(3), 671-682. West Palm Beach (Florida), ISSN 0749-0208.Obtaining accurate information of nearshore wave characteristics including the position and height of individual breaking waves is essential to understanding the drivers of coastal processes, for engineering design and hazard prediction. Demand for such information in real time for recreational planning and hazard assessment is also high. Remote optical techniques would offer considerahle economic and spatial coverage advantages over conventional in situ instrumentation. However, optical methods for obtaining wave height information have been slow to develop and those available remain computationally expensive and require "favourable" environmental conditions. This paper presents a relatively simple yet robust approach to detecting and quantifying breaking wave position and height across a wide surf zone using a twin video camera configuration coupled with an image time-stack analysis approach. A numerical algorithm, HbSTACK, is developed and successfully tested under the environmental conditions experienced during field trials. Errors and uncertainties may arise in both the photogrammetric transformation from pixels to real-world coordinates and in the detection of wave crest and trough positions. These errors have been assessed using both field verification of the transformation model and manually detected crest and trough locations by experienced practitioners. Errors in output wave heights were thus estimated to be less than 1%.ADDITIONAL INDEX WORDS: Wave height. Wave breaking. Surf zone. Optical detection.

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Wave height and wind direction from the HF coastal ocean surface radar

Cited by 33 publications

References 10 publications

Wind-speed inversion from HF radar first-order backscatter signal

Wind-speed inversion from HF radar first-order backscatter signal

HF Ocean Surface Radar Monitoring for Coral Bleaching in the Great Barrier Reef

Automated Detection of Breaking Wave Height Using an Optical Technique

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